Novel signaling aspects of ceramide 1-phosphate

No el signaling aspec s o ce amide 1-phospha e
Na alia P esa1, Ana Gomez-La au i2, Asie Dominguez-He e a1, Miguel T ueba1, and
An onio Gomez-Muñoz1*,
1Depa men o Biochemis y and Molecula Biology, Facul y o Science and Technology,
Uni e si y o he Basque Coun y (UPV/EHU), P.O. Box 644, 48080 Bilbao (Vizcaya), Spain.
2Depa men o Pneumology, C uces Uni e si y Hospi al, Ba akaldo (Vizcaya), Spain.
*Co esponding au ho : Telephone: 34-94-601 2455; FAX: 34-94-601 3500
E-mail: [email p o ec ed]
Abb e ia ions: AA, a achidonic acid, Ak (PKB), p o ein kinase B; BMDM, bone ma ow
de i ed mac ophages; Ce K, ce amide kinase; ClP, ce amide 1-phospha e; cPLA2, calcium
dependen cy osolic phospholipase 2; ERK, ex acellula ly egula ed kinases; GLUT, glucose
anspo e ; iNOS, inducible ni ic oxide syn hase MCP-1, monocy e chemoa ac an p o ein-
1 iNOS, inducible ni ic oxide syn hase; mTOR, mammalian a ge o apamycin; PA,
phospha idic acid; PBK, phospha idylinosi ol 3-kinase; PKC, p o ein kinase C; PTX, pe ussis
oxin; ROS, eac i e oxygen species; SMase, sphingomyelinase; SphK, sphingosine kinase;
SPT, se ine palmi oyl ans e ase; SlP, sphingosinel-phospha e; TAG, iacylglyce ol; VEGF,
ascula endo helial g ow h ac o .
Keywo ds: Bioac i e lipids; ce amides; ce amide kinase; ce amide 1-phospha e; sphingolipids.
1
This is he accep ed manusc ip o he a icle ha appea ed in inal o m in Biochimica e Biophysica Ac a
(BBA) - Molecula and Cell Biology o Lipids 1865(4) : (2020) // A icle ID 158630, which has been
published in inal o m a h ps://doi.o g/10.1016/j.bbalip.2020.158630. © 2020 Else ie unde CC BY-NC-ND
license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
ABSTRACT
The bioac i e sphingolipid ce amide 1-phospha e (ClP) egula es key physiologic cell
unc ions and is implica ed in a numbe o me abolic al e a ions and pa hological p ocesses.
Ini ial s udies using di e en ypes o ib oblas s and monocy es/mac ophages e ealed ha
ClP was mi ogenic and ha i p omo ed cell su i al h ough inhibi ion o apop osis.
Subsequen s udies implica ed ClP in in lamma o y esponses wi h a speci ic ole as p o
in lamma o y agen . Speci ically, ClP po en ly s imula ed cy osolic phospholipase A2 (cPLA2)
esul ing in ele a ion o a achidonic acid and p o-in lamma o y eicosanoid le els. Howe e ,
inc easing expe imen al e idence sugges s ha ClP can also exe an i-in lamma o y ac ions in
so ne cell ypes and issues. Speci ically, i has been demons a ed ha ClP inhibi s he elease
o p o-in lamma o y cy okines and blocks ac i a ion o he p o-in lamma o y ansc ip ion
ac o NF-KB in so ne cell ypes. Mo eo e , ClP was shown o inc ease he elease o an i
in lamma o y in e leukin-1 O in mac ophages, and o o e come ai way in lamma ion and educe
lung emphysema in i o. No ewo hy, ClP s imula ed cell mig a ion, an ac ion ha is
associa ed wi h di e se physiological cell unc ions, as well as wi h in lamma o y esponses
and umo dissemina ion. Mo e ecen ly, ce amide kinase (Ce K), he enzyme ha p oduces
C 1 P in mammalian cells, has been shown o be up egula ed du ing di e en ia ion o p e
adipocy es in o ma u e adipocy es, and ha exogenous C 1 P, ac ing h ough a pu a i e Gi
p o ein-coupled ecep o , nega i ely egula es adipogenesis. Al hough he la e ac ions seem
o be con adic o y, i is plausible ha exogenous ClP may balance he adipogenic e ec s o
in acellula ly gene a ed (Ce K-de i ed) ClP in adipose issue. The p esen e iew highligh s
no el signaling aspec s o ClP and i s impac in he egula ion o cell g ow h and su i al,
in lamma ion and umo dissemina ion.
2
Gloss
Ce amide 1-phospha e is a bioac i e phosphosphingolipid capable o egula ing i al cell
unc ions, including cell g ow h and su i al, and is a key egula o o chemo axis and umo
dissemina ion. ClP and ce amide kinase (Ce K), he enzyme esponsible o i s biosyn hesis in
mammalian cells, a e implica ed in in lamma o y esponses by exe ing ei he p o- and an i
in lamma o y ac ions depending on cell ype o he me abolic con ex o cells. In pa icula ,
adminis a ion o ClP d i es down ai way in lamma ion, educes pulmona y emphysema and
con ols adipogenesis, ac ions ha may ha e po en ial applica ions in he ea men o lung
disease and obesi y.
3
l. In oduc ion
Sphingolipids ha e been classically known as undamen al blocks o euka yo ic cell
memb ane a chi ec u e, howe e so ne o hem play c i ical oles in cell biology. In pa icula ,
he simple sphingolipids, ce amide, sphingosine and hei phospho yla ed o ms egula e key
physiological unc ions and a e implica ed in many pa hological p ocesses [1-3]. Ce amide is
he cen al hub o sphingolipid me abolism and p ecu so o complex sphingolipids [1].
S uc u ally, ce amide is composed o a sphingosine backbone and a a y acid (FA) o a ying
ca bon chain leng hs ha is linked o he sphingosine moie y by and amide bond. A double
bond loca ed be ween ca bons 4 and 5 in ans con igu a ion is o pa icula in e es as i con e s
bioac i i y o he molecule. The impo ance o his double bond is discussed below. Ce amide
can be syn hesized by h ee majo pa hways in ol ing di e en cell compa men s (Fig. 1).
The de no o syn hesis pa hway is an anabolic pa hway ha akes place in he endoplasmic
e iculum (ER) whe e se ine and palmi oyl-CoA a e condensed o o m 3-ke osphinganine (3-
dehyd osphingosine) in a eac ion ha is ca alyzed by se ine palmi oyl ans e ase (SPT), which
is he majo egula o y enzyme o his pa hway. 3-ke osphinganine is hen con e ed o
sphinganine ( dehyd osphingosine) by a educ ase. The nex s ep in ol es he inco po a ion o
a a y acid by sphinganine o ende dihyd oce amide in a eac ion ca alyzed by ce amide
syn hase ac i i y (Ce S). The e a e six di e en Ce S in mammalian cells ha can be
dis inguished by hei a ini ies o di e en a y acyl chain subs a es. In o he wo ds, each
Ce S gi es ise o speci ic ce amide species depending on he leng h o he acyl chain used as
subs a e ( o addi ional in o ma ion on he speci ici y and ole o Ce S in cell biology he
eade is e e ed o elegan e iews by Fu e man and co-wo ke s [ 4-6]). The las s ep o he
pa hway is he in oduc ion o he ans double bond be ween ca bons 4 and 5 o
dihyd oce amide o ende ce amide, a eac ion ha is ca alyzed by desa u ase ac i i y. As
men ioned abo e, his double bond con e s bioac i i y o ce amide, which would o he wise be
4
ine , o a leas no as ac i e, in he o m o dihyd oce amide. In ac , i has been ecen ly
demons a ed ha he lipo oxici y o ce amides o con ibu e o he de elopmen o insulin
esis ance, ype II diabe es and hepa ic s ea osis can be o e come by abla ion o
dehyd oce amide desa u ase 1 in mice he eby p e en ing he con e sion o dehyd oce amide
o ce amide [7]. None heless, a possible pa icipa ion o dihyd oce amide in cell biology canno
be uled ou a he p esen ime as i has been implica ed in he induc ion o cy o oxic au ophagy
in cance cells and an inc ease in ib osis ma ke s in li e cells [8, 9]. Once syn hesized,
ce amides a e anspo ed o he Golgi appa a us whe e hey se e as p ecu so s o complex
sphingolipids such as sphingomyelin (SM) o glycosphingolipids, in eac ions ha a e ca alyzed
by SM syn hase (SMS) and glucosylce amide syn hase (GCS), espec i ely. Speci ically, SM
is syn hesized om ce amides ha a e anspo ed om he ER by ce amide ans e p o ein
(CERT) in a non- esicula anspo manne , whe eas syn hesis o glucosylce amides equi es
esicula anspo o ce amide om he ER o he Golgi appa a us [10-12]. The ans e o
glucosylce amides o he syn hesis o mo e complex glucosphingolipid in ol es pa icipa ion
o he adap o ou -phospha e p o ein (F APP2) [3]. The second majo pa hway o ce amide
syn hesis is a ca abolic pa hway in ol ing he s imula ion o sphingomyelinase ac i i y
(SMase ), which gene a es phosphocholine and ce amides di ec ly om he b eakdown o SM.
This pa hway akes place in he lysosomes and in he plasma memb ane o cells. The e a e i e
di e en ypes o SMases, acidic lysosomal (A-SMase), zn+2-dependen sec e ed A-SMase,
neu al Mg2+-independen and neu al Mg2+-dependen (N-SMase), and alkaline SMase. A
SMases and N-SMases a e mainly in ol ed in signal ansduc ion p ocesses whe eas he majo
ole o he alkaline o m o his enzyme seems o be he deg ada ion o SM ha is inco po a ed
in he die ( o addi ional in o ma ion on he speci ici y and ole o SMases in cell biology he
eade is e e ed o elegan e iews by Hannun and Obeid [1, 13-15]). The hi d majo pa hway
o ce amide syn hesis is he sal age pa hway, which akes place in he ER and mi ochond ia-
5

associa ed memb anes (MAMs). In his pa hway, sphingosine ha is de i ed om he
me abolism o complex sphingolipids is ecycled back o ce amides h ough inco po a ion o a
a y acyl chain in a eac ion ha is ca alyzed by Ce S he eby bypassing dihyd oce amide
o ma ion. I should be emphasized ha sphingosine can only be o med a e ac i a ion o
ca abolic pa hways. A ou h pa hway o ce amide syn hesis was disco e ed in mi ochond ia
whe e neu al ce amidase ca alyzes he condensa ion o sphingosine and palmi oyl-CoA in a
wo-s ep eac ion. Fi s , he a y acyl-CoA chain is hyd olyzed in mi ochond ia o ee FA
(palmi a e) and CoA by hioes e ase ac i i y, a eac ion ha is ollowed by condensa ion o
palmi a e and sphingosine o gene a e ce amide in a e e sed ce amidase eac ion [ 16].
Ce amides con ibu e o he s uc u al s abili y o he cell memb ane and a e en iched in he
ca eolae whe e hey can ac in cell signaling p ocesses. These include he induc ion o cell
cycle a es and apop osis, cell di e en ia ion and he p omo ion o in lamma o y esponses.
No ewo hy, ce amides ha e been implica ed in a a ie y o pa hologies including
ca dio ascula diseases (namely a he oscle osis), insulin esis ance and ype II diabe es,
in lamma o y espi a o y illnesses such as lung emphysema, ch onic obs uc i e pulmona y
disease (COPD), as hma, and pulmona y ib osis, he de elopmen o in lamma o y bowel
disease (namely C ohn's disease and ulce a i e coli is), neu odegene a i e diso de s, mul iple
scle osis, senescence, o cance ( e iewed in [6, 17, 18]). The mechanisms by which ce amides
modula e signal ansduc ion p ocesses include ac i a ion o speci ic se ine/ h eonine p o ein
kinases [19, 20], s imula ion o se ine/ h eonine p o ein phospha ases (PP) [21-23], o
inhibi ion o phospholipase D [24-26]. Fo example, s imula ion o PP2A causes
dephospho yla ion and inac i a ion o Ak , which is a downs eam a ge o
phospha idylinosi ol 3-kinase (PI3K), a key pa hway in ol ed in he p omo ion o cell su i al.
PI3K/Ak is also a majo pa hway by which insulin egula es glucose up ake and me abolism.
In ac , inhibi ion o Ak la gely con ibu es o insulin esis ance and de elopmen o ype 11
6
diabe es [27, 28]. I is also well es ablished ha ce amides can be me abolized u he o
gene a e di e en bioac i e me aboli es. In pa icula , ac i a ion o ce amidases gi es ise o
sphingosine, which can hen be phospho yla ed by wo di e en sphingosine kinases o o m
sphingosine 1-phospha e (S lP). Al ema i ely, ce amides can be phospho yla ed by ce amide
kinase (Ce K) o gene a e ce amide 1-phospha e (ClP) di ec ly. Bo h SlP and ClP a e
bioac i e and can egula e a a ie y o physiologic cell unc ions. Mo eo e , SlP and ClP a e
implica ed in he es ablishmen o p og ession o a ious pa hologies. The in ol emen o S lP
in pa hophysiolological p ocesses is discussed in a ious elegan e isions in his special issue.
The biology o ClP is discussed below.
2. Biosyn hesis and anspo o ce amide 1-phospha e
Up o da e, he only known pa hway o gene a ion o ClP in mammalian cells is he
di ec phospho yla ion o ce amides by Ce K. This kinase has been shown o eside in a ious
cell compa men s including he cy osol, he nucleus and he plasma memb ane, bu i s majo
localiza ion si e is he Golgi appa a us. Ce K phospho yla es ce amides ha a e anspo ed
om he ER o he Golgi by CERT [29]. ClP is also ound in pe inuclea memb anes. Once
syn hesized, C 1 P can be anspo ed by a speci ic ce amide phospha e ans e p o ein ( CPTP)
o he plasma memb ane, whe e i can ac in signal ansduc ion p ocesses, and p obably o
o he o ganelles [29] (Fig. 2). I is possible ha ClP may also be gene a ed by o he pa hways.
Fo example, ans e o a a y acyl-CoA o SlP, o deg ada ion o SM by a D ype
phospholipase would ende ClP di ec ly. Howe e , nei he a SlP acyl ans e ase no a SM
speci ic phospholipase D ha e so a been de ec ed in mammalian cells. This con as s wi h
he obse a ion ha ClP le els we e only educed by abou 50% in cells om mice wi h a
gene ic abla ion o Ce K [30], sugges ing he exis ence o pa hways o enzymes o he han
Ce K o gene a e ClP. Howe e , syn hesis o ClP in cells om Ce K-1-animals migh also be
due o he exis ence o a di e en Ce K iso o m in mammalian cells. O in e es , unpublished
7
wo k o n he Chal an labo a o y indica es ha exogenous addi ion o [32P]S lP o cells in
cul u e led o he p oduc ion o so ne ClP, bu he pe cen age o o al cellula ClP a ibu ed
o his pa hway is s ill unknown [31]. In addi ion, a SMase D capable o gene a ing ClP o n
SM was isola ed o n he eno n o he b own ecluse spide o he gende Loxosceles, and
o n he oxins ha a e p oduced by so ne bac e ia including Co ynebac e ium ube culosis,
A chanobac e ium haemoli icum, o Vib io damsela [32]. Al hough a najo p oduc o SMase
D in he la e o ganis ns is ClP, his enzy ne also ca alyzes a ansphospha idyla ion a he
han a hyd oly ic eac ion in i o, he eby p oducing cyclic-ClP (CC(l,3)P [33]. In e es ingly,
con e sion o SM o CC(l ,3)P has been shown o dis u b phospholipid in eg i y and
no phology, which could a ec ne nb ane asymme y ( he loss o ne nb ane asymme y is a
nechanis n o induce he co nple nen pa hway o he inna e i n nune esponse, which can esul
in cell lysis) [33]. None heless, he possible biological ac ions o cyclic-ClP awai u he
in es iga ion. ClP can also be syn hesized and sec e ed in o he ex acellula en i onmen by
he ancien p o ozoan Gia dia lamblia, an in es inal single-celled pa asi e esponsible o non
bac e ia-associa ed dia heal disease [34].
Al hough Ce K see ns o be he only enzyme i nplica ed in ClP biosyn hesis in
na n nalian cells, ecen wo k sugges s ha sphingo nyelinase phosphodies e ase like 3b
(SMPD3b) nay also con ibu e o nodula ion o ClP le els in podocy es, which a e e minally
di e en ia ed cells o he kidney il a ion ba ie [35]. In ac , o e exp ession o SMPD3b
p e en s he access o Ce K o i s ce a nide subs a e leading o a dec ease in he concen a ion
o in acellula ClP, whe eas gene silencing o SMPD3b wi h speci ic siRNA inc eased o al
ClP le els [35].
8
3. Regula ion o cell p oli e a ion and su i al by ce amide 1-phospha e
The bioac i i y o ClP was i s demons a ed using sho chain ClP analogs (N
ace ylsphingosine-1-phospha e, o C2-C1P, and N-oc anoylsphingosine-1-phospha e, o C8-
C1P). These compounds po en ly s imula ed DNA syn hesis and p oli e a ion in a ib oblas s
[36], an ac ion ha was subsequen ly con i med using na u al (long-chain) ClP also in
ib oblas s [37]. The implica ion o ClP o Ce K in he egula ion o cell g ow h was also
obse ed in addi ional cell ypes including p ima y bone ma ow-de i ed mac ophages
(BMDM) [38], p ima y pho o ecep o p ogeni o s [39], C2C12 myoblas s [40], and di e en
ypes o cance cells such as A549 human lung adenoca cinoma [41], NCI-H358 human
b onchoal eola ca cinoma [16], human neu oblas oma [12], MCF-7 b eas cance [16],
RA W264.7 mouse leukemia [42], o Kaposi sa coma [43]. No ewo hy, epidemiological
s udies om a coho o 2200 b eas cance pa ien s e ealed ha up egula ion o Ce K
exp ession was associa ed wi h umo ecu en ce in women wi h his ype o cance [ 44]. I was
also obse ed ha es ogen ecep o nega i e b eas cance pa ien s wi h high exp ession o
Ce K had a wo se p ognosis han hose wi h low Ce K exp ession [ 45]. The mechanisms
whe eby ClP s imula es cell p oli e a ion in ol e egula ion o a ious signaling pa hways
(Fig. 3). Speci ically, in BMDM, ClP caused phospho yla ion and ac i a ion o ex acellula ly
egula ed kinases 1-2 (ERKl-2) downs eam o MEK (mi ogen-ac i a ed p o ein kinase
kinase ), ac i a ion o PBK and i s downs eam a ge Ak ( also known as p o ein kinase B,
PKB), phospho yla ion o he Ak a ge glycogen syn hase-3P (GSK-3P), c-Jun N e minal
kinase (JNK) and ansc ip ion ac o NF-KB [38]. ClP-s imula ed BMDM p oli e a ion also
in ol ed ansloca ion o p o ein kinase C-a om he cy osol o he plasma memb ane and
subsequen phospho yla ion and ac i a ion o his kinase, ac ions ha we e media ed by SMS
de i ed diacylglyce ol [46]. Fu he s udies demons a ed ha ClP-s imula ed BMDM
p oli e a ion was also unde egula ion o he mammalian a ge o apamycin (mTOR) and i s
9
hema opoie ic s em/p ogeni o cells (HSPC), mul ipo en s omal cells, and human umbilical
ein endo helial cells [7 6-81]. The lis o chemoa ac an s o HSPC is a he sho , so
iden i ica ion o ClP as no el chemo ac ic ac o o hese cells is o pa icula in e es [82].
Mo eo e , ClP s imula ed mig a ion/in asion o co ona y a e y mac o ascula endo helial
cells and e inal mic o ascula endo helial cells h ough binding o he annexin a2/p o ein p 11
ex acellula he e o e ame ic complex (A2 ). Al hough his p o ein complex does no bind ClP
exclusi ely, o he s uc u ally ela ed lipids, including S 1 P and P A could no elici he po en
chemo ac ic s imula ion obse ed wi h ClP [83]. By con as , Chal an and co-wo ke s ound
ha in isola ed ib oblas s o in a model o mouse wound healing in i o, ClP ac s as a nega i e
egula o o cell mig a ion. Speci ically, he in e ac ion o ClP wi h cPLA2 inhibi ed he
mig a ion o ib oblas s in o he wound en i onmen [84, 85], and loss o he ClP-cPLA2
in e ac ion posi i ely a ec ed acu e wound healing [85].
I should also be poin ed ou ha ClP-s imula ed cell mig a ion is no es ic ed o
e eb a es as i also induced mig a ion o p imo dial ge m cells o he gonads in D osophila
[86]. In e es ingly, exogenous ClP also s imula ed glucose up ake and he subsequen
gene a ion o ATP, ac ions ha in ol ed ac i a ion o he PI3K/Ak pa hway and ansloca ion
o he glucose anspo e GLUT3 om he cy osol o he plasma memb ane. The la e ac ions
we e inhibi ed by PTX, sugges ing he in e en ion o a Gi p o ein-coupled ecep o in hese
p ocesses [28]. Since cell mo ili y is a high ene gy-demanding p ocess, ClP s imula ion o
glucose up ake and me abolism should no be su p ising. In addi ion o he chemo ac ic
p ope ies o exogenous ClP, he gene a ion o in acellula ClP ia Ce K up egula ion may
also be an impo an componen o he machine y ha egula es cance cell mig a ion. In his
con ex , we ecen ly showed ha human panc ea ic cance cells mig a e spon aneously in a
Ce K-dependen manne when he cells a e incuba ed in se um- ee medium, in he absence o
16

any po en ial chemoa ac an [74]. Mo e ecen ly, Ce K was also shown o egula e mig a ion
o b eas cance cells [87], and bone ma ow-de i ed mesenchymal s em cells [88].
5. Role o ce amide 1-phospha e in in lamma ion
Ini ial wo k by Chal an and co-wo ke s showed ha ClP p omo ed in lamma ion [31,
84, 89-93] (Fig. 3). This ac ion in ol ed ansloca ion and ac i a ion o g oup IV cy osolic
phospholipase A2 (cPLA2a) and subsequen gene a ion o a achidonic acid (AA) and p o
in lamma o y eicosanoids [84, 89, 93-99]. Using speci ic siRNA o down egula e cPLA2a,
Chal an and co-wo ke s demons a ed ha he induc ion o ClP-s imua ed AA elease was
s ic ly dependen on his phospholipase [89]. Also, he Chal an labo a o y showed ha ClP
bound o he C2/CaLB domains o cPLA2a wi h high speci ici y, as o he s uc u ally ela ed
lipids, including ce amides o SlP did no bind and ailed o ac i a e his enzyme [91]. Binding
o CIP o C2/CaLB domains o cPLA2a inc eased he a ini y o he enzyme o calcium and
p omo ed ansloca ion o he enzyme om he cy osol o he memb anes, whe e he subs a e
is loca ed [89, 100].
The ele ance o in acellula ClP in he p omo ion o in lamma ion was unde sco ed by he
educed le els o p o-in lamma o y cy okines ound in mice ha unde wen gene ic abla ion o
Ce K [30]. Also, cPLA2a may be unde egula ion by PKC, as down egula ion o his kinase
by p olonged incuba ion wi h pho bol-12-my is a e-13-ace a e, o pha macological inhibi ion
o his enzyme po en ly educed ClP-s imula ed AA elease [94]. In addi ion, knockdown o
Ce K by speci ic siRNA o silence he gene encoding his kinase led o inhibi ion o NOX
(NADPH oxidase) and deple ion o eicosanoid p oduc ion in neu oblas oma cells, he eby
implica ing NOX in b ain in lamma ion [101]. Mo e ecen ly, CPTP, he p o ein ha shu les
ClP om i s si e o syn hesis in he Golgi o o he o ganelles, has been in ol ed in
in lammasome ac i a ion. Speci ically, knockdown o CPTP inc eased he elease o p o-
17
in lamma o y IL-lp and IL-18 ia a NLRP3 (Nod-like ecep o amily py in domain con aining
3) in lammasome-based mechanism. CPTP knockdown also induced au ophagy, and ea men
wi h exogenous ClP mimicked bo h s imula ion o p o-in lamma o y cy okine elease and
up egula ion o au ophagy [ 102].
Besides ClP, i s me abolic p ecu so ce amide also has po en p o-in lamma o y
p ope ies, independen ly o i s con e sion o ClP. Fo example, so ne p o-in lamma o y
cy okines including in e leukin (IL)l-be a (IL-lP), umo nec osis-alpha (TNFa), o pla ele 
ac i a ing ac o (PAF) [103, 104] can s imula e SMase ac i i y leading o ce amide gene a ion
and subsequen ac i a ion o p o-in lamma o y NF-KB. Ac i a ion o his ansc ip ion ac o
hen leads o he p oduc ion o addi ional p o-in lamma o y cy okines o chemokines, such as
IL-6, IL-8, RANTES (CCL5) o MCP-1 (CCL2), as well as p o-in lamma o y enzymes ha a e
in ol ed in he syn hesis o p o-in lamma o y eicosanoids [105-108]. Ce amides a e
pa icula ly impo an in in lamma o y lung pa hologies including ch onic obs uc i e
pulmona y disease (COPD), as hma, o lung ib osis [109, 110] and a e he molecula media o s
o pulmona y edema induced by PAF [104]. Mo eo e , emphysema caused by exposu e o
human o mice lungs o ciga e e smoke, was associa ed wi h inc eased le els o ce amides
[111-115]. Howe e , ce amides and ClP ha e opposing e ec s in cells [36], and i was
demons a ed ha ClP blocks many o he ac ions elici ed by ce amides. In pa icula , ClP
subs an ially educed ce amide gene a ion in p o-apop o ic p ima y bone ma ow-de i ed
mac ophages h ough inhibi ion o A-SMase ac i i y [59], o h ough he blockade o SPT and
A- and N-SMase ac i i ies in al eola cells [60]. The la e indings sugges ha ClP migh ha e
an i-in lamma o y p ope ies a leas in lung issue. This hypo hesis was suppo ed by he
obse a ion ha na u al ClP, o he syn he ic analog C8-C1P inhibi ed ciga e e smoke-induced
ai way in lamma ion by deple ing he le els o N-SMase-de i ed ce amides, and blocking p o
in lamma o y cy okine p oduc ion, namely IL-6, IL-1 p, ke a inocy e chemoa ac an (KC),
18
and mac ophage in lamma o y p o ein-2 (MIP-2) [68]. Also, leukocy e in il a ion in
pulmona y issue was po en ly educed by ClP, and o al ea men wi h ClP o C8-C1P
po en ly educed lung emphysema. The la e ac ion was accompanied by educed numbe o
mac ophages and neu ophils in b onchoal eola la age luid and dec eased he le els o p o
in lamma o y cy okines [68]. The an i-in lamma o y ac ions o ClP ha e also been highligh ed
in a ious epo s om di e en g oups showing ha C 1 P po en ly inhibi ed he p oduc ion o
p o-in lamma o y TNFa and NF-KB ac i a ion [116, 117]. Reduc ion o TNFa le els by ClP
in ol ed inhibi ion o he me allop o einase TACE (TNFa con e ing enzyme), he enzyme
ha ca alyzes he con e sion o p o-TNFa o i s ac i e o m in mac ophages [118, 119]. Also,
C 1 P s imula ed he sec e ion o an i-in lamma o y IL-10 in RA W264. 7 mac ophages [ 119], and
ClP subs an ially a enua ed lipopolysaccha ide (LPS)-induced acu e lung inju y by p e en ing
NF-KB ac i a ion in neu ophils. The la e s udies e ealed ha in apulmona y applica ion o
ClP be o e (p ophylac ic) o 24 h a e ( he apeu ic) LPS ins illa ion dec eased neu ophil
a icking o he lung, educed p o-in lamma o y cy okine le els in b onchoal eola la age
luid, and a enua ed al eola capilla y leakage [120]. Mo eo e , knockou o Ce K agg a a ed
pa hological o le hal esponses in mice wi h expe imen al coli is [121]. No ewo hy,
eicosapen enoic acid (EPA), which has shown p omise as he apeu ic agen in many
in lamma o y diseases, including skin in lamma o y illnesses, po en ly inc eased he le els o
ClP in he epide mis he eby con ibu ing o i s an i-in lamma o y capaci y in he skin. By
con as , he le els o SlP emained unchanged ollowing EPA adminis a ion [122]. The
po en ial o ClP as he apeu ic agen in pulmona y in lamma ion was p e iously e iewed
[123]. Al hough oo ea ly o a ibu e a he apeu ic ole o ClP, i could be en isioned ha ClP
analogues migh be p omising ools o ea lung o skin in lamma ion, and could pe haps be
used o coun e ac he dele e ious e ec s o ce amides in o he cell ypes o issues.
19
6. Regula ion o adipogenesis by ce amide 1-phospha e
Adipogenesis is he p ocess by which p e-adipocy es di e en ia e in o na u e
adipocy es. In addi ion o i s ole as ene gy s o age in he o m o iacylglyce ol (TAG), he
adipose issue egula es key physiological cell unc ions h ough he p oduc ion o speci ic
ho mones, na nely lep in, adiponec in and esis in [ 124-126], bu p e-adipocy es and na u e
adipocy es can also sec e e a a ie y o p o- and an i-in lamma o y cy okines, so ne o which
being i nplica ed in insulin esis an , ype II diabe es and obesi y [ 127-129]. In pa icula , lep in
has p o-in lamma o y p ope ies, and as such, i can induce he elease o p o-in lamma o y
cy okines including TNFa, IL-6 o IL-12 [130, 131]. In u n, so ne o he p o-in lamma o y
cy okines can inc ease he le els o lep in in adipose issue, leading o a loop ha po en ia es
he in la n na o y esponse [131, 132]. In a ecen s udy, we de nons a ed ha Ce K was
up egula ed du ing adipocy e di e en ia ion and ha knockdown o his enzy ne using speci ic
siRNA o silence he gene encoding Ce K, o pha macological inhibi ion o his kinase esul ed
in a subs an ial dec ease o lipid d ople o ma ion and TAG le els in he adipocy es [133]. The
la e indings a e consis en wi h p e ious wo k by Cla o and co-wo ke s showing ha Ce K
egula es lipid d ople biogenesis h ough ac i a ion o cPLA2a [134]. In addi ion, Ce K
knockdown caused signi ican educ ion o lep in sec e ion, which is also a c ucial adipokine
o con olling appe i e and ene gy ho neos asis in he o ganis n. Mo eo e , i is known ha
lep in le els a e ele a ed in he obese s a e. The educ ion o lep in sec e ion caused by
down egula ion o Ce K would lead o a enua ion o he p o-in lamma o y esponse, an ac ion
ha would i npac in he con ex o obesi y, which is a low-g ade in lamma o y disease. O
in e es , and con a y o he adipogenic e ec o Ce K-gene a ed in acellula ClP,
ad ninis a ion o exogenous ClP o p e-adipocy es inhibi ed hei di e en ia ion in o na u e
adipocy es and led o a educ ion in he accu nula ion o lipid d ople s and deple ion o T AG
le els in hese cells [135]. Fu he mo e, exogenous ClP caused a na ked educ ion in he
20
exp ession o he ea ly and la e adipogenic ma ke s C/EBPP and PP ARy, and subs an ially
educed lep in sec e ion by hese cells. The mechanism by which exogenous ClP inhibi s
adipocy e di e en ia ion in ol ed ERK.1-2 ac i a ion, an ac ion ha was comple ely blocked
by PTX. Also, PTX comple ely es o ed he educ ion o T AG le els and lep in sec e ion caused
by exogenous ClP du ing adipogenesis, sugges ing he in e en ion o a Gi p o ein-coupled
ecep o in his p ocess [135]. In addi ion, adminis a ion o ClP du ing adipogenesis
signi ican ly educed Ce K ac i i y [135] sugges ing ha exogenous ClP may balance he
adipogenic ac ion o Ce K-de i ed in acellula ClP in pa by educing Ce K ac i a ion. In
ag eemen wi h he la e obse a ions, exogenous ClP also nega i ely egula ed Ce K in
di e en ia ed human podocy es [35]. The e o e, i seems plausible ha ClP can exe dual
ac ions depending on whe he i is gene a ed in acellula ly o ac ing exogenously h ough i s
pu a i e ecep o o con ol adipogenesis (Fig. 3).
7. O he biological ac ions o ClP
In addi ion o egula ing he physiologic and pa hologic p ocesses men ioned abo e,
ClP has also been shown o pa icipa e in o he biological ac i i ies. Speci ically, in a mu ine
model o hindlimb ischemia, Mena and co-wo ke s [63] showed ha local adminis a ion o
ClP alone p omo ed blood pe usion and educed nec osis in he ischemic muscle. The
bene icia! e ec s o endo helial colony- o ming cell in usion a e ischemia induced in his
model we e ampli ied by ClP p e ea men , esul ing in u he enhancemen o leg epe usion
and muscle epai . Mo eo e , i has been ecen ly shown ha ClP can inc ease asculogenesis
bo h in i o and in i o [63], and ha p iming wi h ClP p omo es he he apeu ic e ec o
mesenchymal s em/s omal cells on pulmona y a e y hype ension [136]. I should also be
poin ed ou ha dopamine anspo e a icking is egula ed by he N-SMase-2/Ce K pa hway.
The dopamine anspo e egula es dopamine eup ake om he synap ic cle , enabling
21

e mina ion o dopamine gic signaling and egula ing cellula dopamine ecycling sys ems
[137]. I has also been epo ed ha ClP le els a e inc eased in he sub en icula zone (SVZ)
o b ains om pa ien s wi h Hun ing on's disease (HD) (pos mo em). The highe le els o
ClP in HD SVZ we e associa ed wi h he b eakdown o SVZ myelin, whe e inc eased le els
o Ca2+ s imula ed Ce K ac i i y he eby enhancing ce amide phospho yla ion [138]. Mo eo e ,
FTY720 ( also known as ingolimod), a d ug used o he ea men o mul iple scle osis, which
is capable o pene a ing he blood-b ain ba ie [139] and o up egula e Ce K, has been shown
o amelio a e Alzheime 's disease [140]. In he same line o in es iga ion, o al adminis a ion
o FTY720 o a mouse model o die induced non-alcoholic a y li e disease imp o ed glucose
ole ance and s ea osis [141], a inding ha is consis en wi h he ole o Ce K in dec easing he
le els o p o-in lamma o y ce amides in li e , and he imp o emen o s ea osis in
phospha idyle hanolamine me hyl ans e ase de icien mice, in which Ce K was up egula ed
[142]. Also, ClP (speci ically C22-C1P species) was ele a ed in Fa be disease, a a e
lysosomal s o age diso de cha ac e ized by acid ce amidase de iciency and ele a ion o
a ious p o-in lamma o y cy okines and chemokines including VEGF and MCP-1 [143]. In
ag eemen wi h he la e obse a ion, we showed ecen ly ha ClP inc eased he sec e ion o
VEGF [ 42] and MCP-1 [70] in mac ophages, ac ions ha we e associa ed wi h he s imula ion
o mac ophage p oli e a ion and mig a ion, espec i ely.
8. Concluding ema ks
The biological ac ions elici ed by ClP a e c ucial o main aining an app op ia e balance
be ween cell g ow h and dea h, and he sui able egula ion o chemo axis. Whils Ce K-de i ed
in acellula ClP seems o be implica ed in con olling cell numbe in a ecep o -independen
manne , ex acellula ClP go e ns cell mo ili y h ough in e ac ion wi h a pu a i e Gi p o ein
coupled ecep o . Any al e a ion in he le els o ClP, ei he in a- o ex acellula , would cause
unwan ed side e ec s and likely esul in disease. Speci ically, up egula ion o he in acellula
22
le els o ClP would dec ease ce amide le els a o ing cell p oli e a ion and educing cell
dea h, ac ions ha migh lead o uncon olled cell g ow h and umo igenesis. By con as ,
educ ion o in acellula ClP concen a ions would inc ease ce amide le els o acili a e cell
dea h and he de elopmen o diseases associa ed wi h apop osis (i.e., neu odegene a i e
illnesses such as Alzheime ' s o Pa kinson disease ). Conceming chemo axis, mig a ion o cells
o inapp op ia e si es in he o ganism would cause al e a ions in issue homeos asis,
in lamma ion, o umo dissemina ion in he case o malignan cells. Mo eo e , he Ce K/ClP
axis seems o be essen ial o con olling adipogenesis, which is associa ed wi h de elopmen
o obesi y. Whils in acellula Ce K-de i ed ClP le els inc ease du ing di e en ia ion o p e
adipocy es in o ma u e adipocy es, exogenous ClP may be eleased o balance ou adipogenesis
by educing o ma ion o lipid d ople s and dec easing TAG con en in he adipocy es. Whe he
a ge ing Ce K may be a way o po en ial applica ions in he ea men o cance o obesi y
awai s u he in es iga ion.
Acknowledgemen s
Wo k in AGM labo a o y is suppo ed by "Depa amen o de Educación del Gobie no
Vasco (Gaz eiz-Vi o ia, Basque Coun y, Spain)" g an numbe IT-1106-16, and "Minis e io
de Ciencia, Inno ación y Uni e sidades" (Mad id, Spain)" g an numbe SAF2016-79695-R.
Re e ences
[
1]Y.A. Hannun, L.M. Obeid, P incipies o bioac i e lipid signalling: lessons om
sphingolipids, Na Re Mol Cell Biol 9 (2) (2008) 139-150.
[2]M. Maceyka, S. Spiegel, Sphingolipid me aboli es in in lamma o y disease, Na u e 510
(7503) (2014) 58-67.
[3]T. Hla, A.J. Dannenbe g, Sphingolipid signaling in me abolic diso de s, Cell Me ab 16
(4) (2012) 420-434.
23
[ 4] I.D. Zelnik, A.E. Ven u a, J.L. Kim, L.C. Sil a, AH. Fu e man, The ole o ce amide in
egula ing endoplasmic e iculum unc ion, Biochim Biophys Ac a Mol Cell Biol Lipids
(2019)
[5] J.W. Pa k, W.J. Pa k, AH. Fu e man, Ce amide syn hases as po en ial a ge s o
he apeu ic in e en ion in human diseases, Biochim Biophys Ac a 1841 (5) (2014) 671-
681.
[6] J. Ku z, M.J. Pa nham, G. Geisslinge , S. Schi mann, Ce amides as No el Disease
Bioma ke s, T ends Mol Med 25 (1) (2019) 20-32.
[7] B. Chau asia, T.S. Tippe s, R. Mayo al Monibas, J. Liu, Y. Li, L. Wang, J.L. Wilke son,
C.R. Sweeney, R.F. Pe ei a, D.H. Sumida, J.A. Maschek, J.E. Cox, V. Kaddai, G.I.
Lancas e , M.M. Siddique, A. Poss, M. Pea son, S. Sa apa i, H. Zhou, D.G. McLa en,
S.F. P e is, Y. Chen, Y. Qian, A. Pe o , M. Wu, X. Shen, J. Yao, C.N. Nunes, AD.
Howa d, M.D. E ion, J. Ru e , W.L. Holland, D.E. Kelley, S.A. Summe s, Ta ge ing a
ce amide double bond imp o es insulin esis ance and hepa ic s ea osis, Science 365
(6451) (2019) 386-392.
[8] S. Hemandez-Tied a, G. Fab ias, D. Da ila, I.J. Salanue a, J. Casas, L.R. Mon es, Z.
An on, E. Ga cia-Taboada, M. Salaza -Roa, M. Lo en e, J. Nylands ed, J. A ms ong, l.
Lopez-Vale o, C.S. McKee, A. Se ano-Puebla, R. Ga cia-Lopez, J. Gonzalez-Ma inez,
J.L. Abad, K. Hanada, P. Boya, F. Goni, M. Guzman, P. Lo a , M. Jaa ela, A. Alonso,
G. Ve lasco, Dihyd oce amide accumula ion media es cy o oxic au ophagy o cance cells
ia au olysosome des abiliza ion, Au ophagy 12 (11) (2016) 2213-2229.
[9] A.Y. Lee, J.W. Lee, J.E. Kim, H.J. Mock, S. Pa k, S. Kim, S.H. Hong, J.Y. Kim, E.J.
Pa k, K.S. Kang, K.P. Kim, M.H. Cho, Dihyd oce amide is a key me aboli e ha
egula es au ophagy and p omo es ib osis in hepa ic s ea osis model, Biochem Biophys
Res Commun 494 (3-4) (2017) 460-469.
[ 10] M. Rabano, A. Pena, L. B izuela, A. Ma ino, J.M. Maca ulla, M. T ueba, A. Gomez
Munoz, Sphingosine-1-phospha e s imula es co isol sec e ion, FEBS Le 535 (1-3)
(2003) 101-105.
[11] T.J. Kim, Y.J. Kang, Y. Lim, H.W. Lee, K. Bae, Y.S. Lee, J.M. Yoo, H.S. Yoo, Y.P. Yun,
Ce amide 1-phospha e induces neoin imal o ma ion ia cell p oli e a ion and cell cycle
p og ession ups eam o ERKl/2 in ascula smoo h muscle cells, Exp Cell Res 317 (14)
(2011) 2041-2051.
[12] F. Bini, A. F a i, M. Ga cia-Gil, C. Ba is ini, M. G anado, M. Ma inesi, M. Maina di,
E. Vannini, F. Luzza i, M. Caleo, P. Pe e o, A. Gomez-Munoz, E. Meacci, New
24
signalling pa hway in ol ed in he an i-p oli e a i e ac ion o i amin D(3) and i s
analogues in human neu oblas oma cells. A ole o ce amide kinase,
Neu opha macology 63 (4) (2012) 524-537.
[13] F.M. Goni, A. Alonso, Sphingomyelinases: enzymology and memb ane ac i i y, FEBS
Le 531 (1) (2002) 38-46.
[ 14] A. Alonso, F .M. Goni, The Physical P ope ies o Ce amides in Memb anes, Annu Re
Biophys 47 (2018) 633-654.
[15] R.D. Duan, Alkaline sphingomyelinase (NPP7) in hepa obilia y diseases: A ield ha
needs o be closely s udied, Wo ld J Hepa ol 10 (2) (2018) 246-253.
[16] O. Pas ukho , S. Schwalm, U. Zangemeis e -Wi ke, D. Fabb o, F. Bomancin, L. Jap ok,
B. Kleuse , J. P eilschi e , A. Huwile , The ce amide kinase inhibi o NVP-231 inhibi s
b eas and lung cance cell p oli e a ion by inducing M phase a es and subsequen cell
dea h, B J Pha macol 171 (24) (2014) 5829-5844.
[17] N. P esa, A. Gomez-La au i, I.G. Ri e a, M. O donez, M. T ueba, A. Gomez-Munoz,
Regula ion o cell mig a ion and in lamma ion by ce amide 1-phospha e, Biochim
Biophys Ac a 1861 (5) (2016) 402-409.
[18] A. Gomez-Munoz, N. P esa, A. Gomez-La au i, I.G. Ri e a, M. T ueba, M. O donez,
Con ol o in lamma o y esponses by ce amide, sphingosine 1-phospha e and ce amide
1-phospha e, P og Lipid Res 61 (2016) 51-62.
[19] R. Kolesnick, D.W. Golde, The sphingomyelin pa hway in umo nec osis ac o and
in e leukin-1 signaling, Cell 77 (3) (1994) 325-328.
[20] S. Ma hias, K.A. D essle , R.N. Kolesnick, Cha ac e iza ion o a ce amide-ac i a ed
p o ein kinase: s imula ion by umo nec osis ac o alpha, P oc Na l Acad Sci USA 88
(22) (1991) 10009-10013.
[21] Y.A. Hannun, The sphingomyelin cycle and he second messenge unc ion o ce amide,
J Biol Chem 269 (5) (1994) 3125-3128.
[22] D. Canals, P. Roddy, Y.A. Hannun, P o ein phospha ase lalpha media es ce amide
induced ERM p o ein dephospho yla ion: a no el mechanism independen o
phospha idylinosi ol 4, 5-biphospha e (PIP2) and myosin/ERM phospha ase, J Biol Chem
287 (13) (2012) 10145-10155.
[23] S.A. Saddoughi, S. Gence , Y.K. Pe e son, K.E. Wa d, A. Mukhopadhyay, J. Oaks, J.
Bielawski, Z.M. Szulc, R.J. Thomas, S.P. Sel am, C.E. Senkal, E. Ga e -Maye , R.M.
De Palma, D. Feda o ich, A. Liu, A.A. Habib, R.V. S ahelin, D. Pe o i, B. Og e men,
Sphingosine analogue d ug FTY720 a ge s l2PP2A/SET and media es lung umou
25
[84] B.J. Pe us, A. Bielawska, S. Spiegel, P. Roddy, Y.A. Hannun, e.E. ehal an , ee amide
kinase media es cy okine- and calcium ionopho e-induced a achidonic acid elease, J Biol
ehem 278 (40) (2003) 38206-38213.
[85] H.P. MacKnigh , D.J. S ephenson, L.A. Hoe e lin, S.D. Benusa, J.T. DeLigio, K.D.
Maus, A.N. Ali, J.S. Wayne, M.A. Pa k, E.H. Hinchcli e, R.E. B own, J.J. Ryan, R.F.
Diegelmann, e.E. ehal an , The in e ac ion o ce amide 1-phospha e wi h g oup IV A
cy osolic phospholipase A2 coo dina es acu e wound healing and epai , Sci Signal 12
(610) (2019)
[86] M.A. McElwain, D.e. Ko, M.D. Go don, H. Fy s , J.D. Saba, R. Nusse, A
supp esso /enhance sc een in D osophila e eals a ole o wn -media ed lipid
me abolism in p imo dial ge m cell mig a ion, PLoS One 6 (11) (2011) e26993.
[87] B. Newcomb, e. Rhein, l. Mile a, R. Ahmad, e.J. ela ke, J. Snide , L.M. Obeid, Y.A.
Hannun, Iden i ica ion o an acid sphingomyelinase ce amide kinase pa hway in he
egula ion o he chemokine eeL5, J Lipid Res 59 (7) (2018) 1219-1229.
[88] J. Yu, H.M. Kim, K.P. Kim, Y. Son, M.S. Kim, K.S. Pa k, ee amide kinase egula es he
mig a ion o bone ma ow-de i ed mesenchymal s em cells, Biochem Biophys Res
eommun 508 (2) (2019) 361-367.
[89] B.J. Pe us, A. Bielawska, P. Sub amanian, D.S. Wijesinghe, M. Maceyka, e.e. Leslie,
J.H. E ans, J. F eibe g, P. Roddy, Y.A. Hannun, e.E. ehal an , ee amide 1-phospha e is
a di ec ac i a o o cy osolic phospholipase A2, J Biol ehem 279 (12) (2004) 11320-
11326.
[90] e.E. ehal an , S. Spiegel, Sphingosine 1-phospha e and ce amide 1-phospha e:
expanding oles in cell signaling, J eell Sci 118 (P 20) (2005) 4605-4612.
[91] L.A. Hoe e lin, D.S. Wijesinghe, e.E. ehal an , The ole o ce amide-1-phospha e in
biological unc ions, Handb Exp Pha macol (215) (2013) 153-166.
[92] N.F. Lamou , e.E. ehal an , ee amide-1-phospha e: he "missing" link in eicosanoid
biosyn hesis and in lamma ion, Mol In e 5 (6) (2005) 358-367.
[93] N.F. Lamou , P. Sub amanian, D.S. Wijesinghe, R.V. S ahelin, J.V. Bon en e, e.E.
ehal an , ee amide 1-phospha e is equi ed o he ansloca ion o g oup IV A cy osolic
phospholipase A2 and p os aglandin syn hesis, J Biol ehem 284 (39) (2009) 26897-
26907.
[94] H. Nakamu a, T. Hi abayashi, M. Shimizu, T. Mu ayama, ee amide-1-phospha e
ac i a es cy osolic phospholipase A2alpha di ec ly and by PKe pa hway, Biochem
Pha macol 71 (6) (2006) 850-857.
32

[95] K.E. Wa d, N. Bha dwaj, M. Vo a, C.E. Chal an , H. Lu, R.V. S ahelin, The molecula
basis o ce amide-1-phospha e ecogni ion by C2 domains, J Lipid Res 54 (3) (2013) 636-
648.
[96] N.F. Lamou , C.E. Chal an , Ce amide kinase and he ce amide-1-
phospha e/cPLA2alpha in e ac ion as a he apeu ic a ge , Cu D ug Ta ge s 9 (8) (2008)
674-682.
[97] P. Sub amanian, R.V. S ahelin, Z. Szulc, A. Bielawska, W. Cho, C.E. Chal an , Ce amide
1-phospha e ac s as a posi i e allos e ic ac i a o o g oup IV A cy osolic phospholipase
A2 alpha and enhances he in e ac ion o he enzyme wi h phospha idylcholine, J Biol
Chem 280 (18) (2005) 17601-17607.
[98] D.S. Wijesinghe, P. Sub amanian, N.F. Lamou , L.B. Gen ile, M.H. G anado, A.
Bielawska, Z. Szulc, A. Gomez-Munoz, C.E. Chal an , Chain leng h speci ici y o
ac i a ion o cPLA2alpha by ClP: use o he dodecane deli e y sys em o de e mine lipid
speci ic e ec s, J Lipid Res 50 (10) (2009) 1986-1995.
[99] S. Mi su ake, T.J. Kim, Y. Inagaki, M. Ka o, T. Yamashi a, Y. Iga ashi, Ce amide kinase
is a media o o calcium-dependen deg anula ion in mas cells, J Biol Chem 279 (17)
(2004) 17570-17577.
[100] R.V. S ahelin, P. Sub amanian, M. Vo a, W. Cho, C.E. Chal an , Ce amide-1-phospha e
binds g oup IV A cy osolic phospholipase a2 ia a no el si e in he C2 domain, J Biol
Chem 282 (28) (2007) 20467-20474.
[101] B.M. Ba h, S.J. Gus a son, J.L. Hankins, J.M. Kaise , J.K. Haakenson, M. Kes e , T.B.
Kuhn, Ce amide kinase egula es TNFalpha-s imula ed NADPH oxidase ac i i y and
eicosanoid biosyn hesis in neu oblas oma cells, Cell Signal 24 (6) (2012) 1126-1133.
[102] S.K. Mish a, Y.G. Gao, Y. Deng, C.E. Chal an , E.H. Hinchcli e, R.E. B own, CPTP: A
sphingolipid ans e p o ein ha egula es au ophagy and in lammasome ac i a ion,
Au ophagy 14 (5) (2018) 862-879.
[103] R.W. Jenkins, D. Canals, J. Idkowiak-Baldys, F. Simba i, P. Roddy, D.M. Pe y, K.
Ki a ani, C. Lube o, Y.A. Hannun, Regula ed sec e ion o acid sphingomyelinase:
implica ions o selec i i y o ce amide o ma ion, J Biol Chem 285 (46) (2010) 35706-
35718.
[104] R. Goggel, S. Wino o-Mo bach, G. Vielhabe , Y. Imai, K. Lindne , L. B ade, H. B ade,
S. Ehle s, AS. Slu sky, S. Schu ze, E. Gulbins, S. Uhlig, PAF-media ed pulmona y
edema: a new ole o acid sphingomyelinase and ce amide, Na Med 10 (2) (2004) 155-
160.
33
[105] K.A. Becke , J. Rie hmulle , Y. Zhang, E. Gulbins, The ole o sphingolipids and
ce amide in pulmona y in lamma ion in cys ic ib osis, Open Respi Med J 4 (2010) 39-
47.
[106] S.K. Manna, B.B. Agga wal, IL-13 supp esses TNF-induced ac i a ion o nuclea ac o 
kappa B, ac i a ion p o ein-1, and apop osis, J Immunol 161 (6) (1998) 2863-2872.
[107] G.F. Nixon, Sphingolipids in in lamma ion: pa hological implica ions and po en ial
he apeu ic a ge s, B J Pha macol 158 (4) (2009) 982-993.
[ 108] C. Xiao, S. Ghosh, NF-kappaB, an e olu iona ily conse ed media o o immune and
in lamma o y esponses, Ad Exp Med Biol 560 (2005) 41-45.
[109] l. Pe ache, D.N. Pe usca, R.P. Bowle , K. Kamocki, In ol emen o ce amide in cell
dea h esponses in he pulmona y ci cula ion, P oc Am Tho ac Soc 8 (6) (2011) 492-496.
[ 11 O] E.L. Smi h, E.H. Schuchman, The unexpec ed ole o acid sphingomyelinase in cell dea h
and he pa hophysiology o common diseases, F ASEB J 22 (1 O) (2008) 3419-3431.
[111] l. Pe ache, V. Na a ajan, L. Zhen, T.R. Medle , A.T. Rich e , C. Cho, W.C. Hubba d,
E.V. Be dyshe , R.M. Tude , Ce amide up egula ion causes pulmona y cell apop osis
and emphysema-like disease in mice, Na Med 11 (5) (2005) 491-498.
[112] l. Pe ache, T.R. Medle , A.T. Rich e , K. Kamocki, U. Chukwueke, L. Zhen, Y. Gu, J.
Adamowicz, K.S. Schwei ze , W.C. Hubba d, E.V. Be dyshe , G. Lunga ella, R.M.
Tude , Supe oxide dismu ase p o ec s agains apop osis and al eola enla gemen
induced by ce amide, Am J Physiol Lung Cell Mol Physiol 295 (1) (2008) L44-53.
[113] M. Le y, E. Khan, M. Ca eaga, T. Goldkom, Neu al sphingomyelinase 2 is ac i a ed by
ciga e e smoke o augmen ce amide-induced apop osis in lung cell dea h, Am J Physiol
Lung Cell Mol Physiol 297 (1) (2009) Ll25-133.
[114] M. Bodas, T. Min, N. Vij, C i ica! ole o CFTR-dependen lipid a s in ciga e e smoke
induced lung epi helial inju y, Am J Physiol Lung Cell Mol Physiol 300 ( 6) (2011) L8 l 1-
820.
[115] S. Filos o, S. Cas illo, A. Danielson, L. F anzi, E. Khan, N. Kenyon, J. Las , K. Pinke on,
R. Tude , T. Goldkom, Neu al sphingomyelinase 2: a no el a ge in ciga e e smoke
induced apop osis and lung inju y, Am J Respi Cell Mol Biol 44 (3) (2011) 350-360.
[116] S. Joze owski, M. Cze kies, A. Lukasik, A. Bielawska, J. Bielawski, K. Kwia kowska,
A. Sobo a, Ce amide and ce amide 1-phospha e a e nega i e egula o s o TNF-alpha
p oduc ion induced by lipopolysaccha ide, J Immunol 185 (11) (2010) 6960-6973.
34
[117] J.L. Hankins, T.E. Fox, B.M. Ba h, K.A. Un a h, M. Kes e , Exogenous ce amide-1-
phospha e educes lipopolysaccha ide (LPS)-media ed cy okine exp ession, J Biol Chem
286 (52) (2011) 44357-44366.
[118] N.F. Lamou , D.S. Wijesinghe, J.A. Mie la, K.E. Wa d, R.V. S ahelin, C.E. Chal an ,
Ce amide kinase egula es he p oduc ion o umo nec osis ac o alpha (TNFalpha) ia
inhibi ion o TNFalpha-con e ing enzyme, J Biol Chem 286 (50) (2011) 42808-42817.
[119] S. Ka z, O. Ems , D. A ni, M. A hamna, A. Philosoph, L. A ana, A. Ou o, L.A. Hoe e lin,
M.M. Meijle , C.E. Chal an , A. Gomez-Munoz, T. Zo , Exogenous ce amide-1-
phospha e (ClP) and phospho-ce amide analogue-1 (PCERA-1) egula e key
mac ophage ac i i ies ia dis inc ecep o s, Immunol Le 169 (2016) 73-81.
[120] K. Baudiss, R. de Paula Viei a, S. Cicko, K. Aya a, M. Hoss eld, N. Eh a , A. Gomez
Munoz, H.K. El zschig, M. Idzko, ClP A enua es Lipopolysaccha ide-Induced Acu e
Lung Inju y by P e en ing NF-kappaB Ac i a ion in Neu ophils, J Immunol 196 (5)
(2016) 2319-2326.
[121] S. Suzuki, A. Tanaka, H. Nakamu a, T. Mu ayama, Knockou o Ce amide Kinase
Agg a a es Pa hological and Le hal Responses in Mice wi h Expe imen al Coli is, Biol
Pha m Bull 41 (5) (2018) 797-805.
[122] A.C. Kendall, M. Kiezel-Tsuguno a, L.C. B ownb idge, J.L. Ha wood, A. Nicolaou,
Lipid unc ions in skin: Di e en ial e ec s o n-3 polyunsa u a ed a y acids on
cu aneous ce amides, in a human skin o gan cul u e model, Biochim Biophys Ac a
Biomemb 1859 (9 P B) (2017) 1679-1689.
[123] A. Gomez-La au i, M. T ueba, A. Gomez-Munoz, Po en ial o ce amide 1-phospha e as
a no el he apeu ic agen in pulmona y in lamma ion, Expe Re Clin Pha macol 9 ( 5)
(2016) 629-631.
[124] Y. Zhang, R. P oenca, M. Ma ei, M. Ba one, L. Leopold, J.M. F iedman, Posi ional
cloning o he mouse obese gene and i s human homologue, Na u e 372 (6505) (1994)
425-432.
[125] P.E. Sche e , S. Williams, M. Fogliano, G. Baldini, H.F. Lodish, A no el se um p o ein
simila o Clq, p oduced exclusi ely in adipocy es, J Biol Chem 270 (45) (1995) 26746-
26749.
[126] C.M. S eppan, S.T. Bailey, S. Bha , E.J. B own, R.R. Bane jee, C.M. W igh , H.R. Pa el,
R.S. Ahima, M.A. Laza , The ho mone esis in links obesi y o diabe es, Na u e 409
(6818) (2001) 307-312.
35
[127] K. Sa jean , J.M. S ephens, Adipogenesis, Cold Sp ing Ha b Pe spec Biol 4 (9) (2012)
a008417.
[ 128] J. Y e, Eme ging ole o adipose issue hypoxia in obesi y and insulin esis ance, In J
Obes (Lond) 33 (1) (2009) 54-66.
[129] K. Meije , M. de V ies, S. Al-Lahham, M. B uinenbe g, D. Weening, M. Dijks a, N.
Kloos e huis, R.J. an de Leij, H. an de Wan , B.J. K oesen, R. Vonk, F. Rezaee,
Human p ima y adipocy es exhibi immune cell unc ion: adipocy es p ime in lamma ion
independen o mac ophages, PLoS One 6 (3) (2011) e 17154.
[130] J. Shen, l. Sakaida, K. Uchida, S. Te ai, K. Oki a, Lep in enhances TNF-alpha p oduc ion
ia p38 and JNK MAPK in LPS-s imula ed Kup e cells, Li e Sci 77 (13) (2005) 1502-
1515.
[ 131] N. Iikuni, Q .L. Lam, L. Lu, G. Ma a ese, A. La Ca a, Lep in and In lamma ion, Cu
Immunol Re 4 (2) (2008) 70-79.
[132] V. Abella, M. Sco ece, J. Conde, J. Pino, M.A. Gonzalez-Gay, J.J. Gomez-Reino, A.
Me a, F. Lago, R. Gomez, O. Gualillo, Lep in in he in e play o in lamma ion,
me abolism and immune sys em diso de s, Na Re Rheuma ol 13 (2) (2017) 100-109.
[133] M. O donez, N. P esa, M. T ueba, A. Gomez-Munoz, Implica ion o Ce amide Kinase in
Adipogenesis, Media o s In lamm 2017 (2017) 9374563.
[134] A. Gubem, M. Ba celo-Toms, D. Bameda, J.M. Lopez, R. Masg au, F. Pica os e, C.E.
Chal an , J. Balsinde, M.A. Balboa, E. Cla o, JNK and ce amide kinase go em he
biogenesis o lipid d ople s h ough ac i a ion o g oup IV A phospholipase A2, J Biol
Chem 284 (47) (2009) 32359-32369.
[135] M. O donez, N. P esa, A. Dominguez-He e a, M. T ueba, A. Gomez-Munoz, Regula ion
o adipogenesis by ce amide 1-phospha e, Exp Cell Res 372 (2) (2018) 150-157.
[136] J. Lim, Y. Kim, J. Heo, K.H. Kim, S. Lee, S.W. Lee, K. Kim, I.G. Kim, D.M. Shin,
P iming wi h ce amide-1 phospha e p omo es he he apeu ic e ec o mesenchymal
s em/s omal cells on pulmona y a e y hype ension, Biochem Biophys Res Commun
473 (1) (2016) 35-41.
[137] J.H. Won, S.K. Kim, I.C. Shin, H.C. Ha, J.M. Jang, M.J. Back, D.K. Kim, Dopamine
anspo e a icking is egula ed by neu al sphingomyelinase 2/ce amide kinase, Cell
Signal 44 (2018) 171-187.
[138] M. Hun e , N.J. Dema ais, R.L.M. Faull, A.C. G ey, M.A. Cu is, Sub en icula zone
lipidomic a chi ec u e loss in Hun ing on's disease, J Neu ochem 146 (5) (2018) 613-630.
36
[139] S.F. Hun e , J.D. Bowen, A.T. Rede , The Di ec E ec s o Fingolimod in he Cen al
Ne ous Sys em: Implica ions o Relapsing Mul iple Scle osis, CNS D ugs 30 (2) (2016)
135-147.
[140] H. Jesko, P.L. Wencel, W.J. Lukiw, R.P. S osznajde , Modula o y E ec s o Fingolimod
(FTY720) on he Exp ession o Sphingolipid Me abolism-Rela ed Genes in an Animal
Model o Alzheime 's Disease, Mol Neu obiol 56 (1) (2019) 174-185.
[141] T.D. Roh bach, A. Asgha pou , M.A. Maczis, D. Mon e usco, L.A. Cowa , P. Bedossa,
A.J. Sanyal, S. Spiegel, FTY720/ ingolimod dec eases hepa ic s ea osis and exp ession
o a y acid syn hase in die -induced nonalcoholic a y li e disease in mice, J Lipid Res
60 (7) (2019) 1311-1322.
[142] N. P esa, R.D. Clugs on, S. Ling ell, S.E. Kelly, A.H. Me ill, J ., S. Jana, Z. Kassi i, A.
Gomez-Munoz, D.E. Vanee, R.L. Jacobs, J.N. an de Veen, Vi amin E alle ia es non
alcoholic a y li e disease in phospha idyle hanolamine N-me hyl ans e ase de icien
mice, Biochim Biophys Ac a Mol Basis Dis 1865 (1) (2019) 14-25.
[143] S. Dwo ski, P. Lu, A. Khan, B. Ma anda, J.J. Mi chell, R. Pa ini, M. Di Rocco, B. Hugle,
M. Y oshimi su, B. Magnusson, B. Makay, N. A slan, N. Guelbe , K. Ehle , A. Ja isch,
J. Ga dne -Medwin, R. Daghe , M.T. Te e i, C.M. Lo enco, L. Ba illas-A ias, P.
Tanpaiboon, A. Solyom, J.S. No is, X. He, E.H. Schuchman, T. Le ade, J.A. Medin,
Acid Ce amidase De iciency is cha ac e ized by a unique plasma cy okine and ce amide
p o ile ha is al e ed by he apy, Biochim Biophys Ac a Mol Basis Dis 1863 (2) (2017)
386-394.
37

Figu e legends
Fig. l. Biosyn hesis o simple sphingolipids. Ce amide is he cen al hub o sphingolipid
me abolism. I can be p oduced by h ee majo pa hways: 1) he de no o syn hesis pa hway is
an anabolic pa hway in ol ing he coo dina ed ac ions o se ine palmi oyl-CoA ans e ase
(SPT), ce amide syn hase (Ce S), and desa u ase (DES) ac i i ies (g een a ea); 2) he
sphingomyelinase (SMase) pa hway is a ca abolic pa hway ha gene a es ce amide di ec ly
om he b eakdown o sphingomyelin (SM) by s imula ion o di e en SMases. The e e sed
eac ion is ca alyzed by SM syn hases o gene a e SM (Pu ple a ea); 3) he sal age pa hway is
a ca abolic pa hway ha uses sphingosine de i ed om he me abolism o complex
sphingolipids o o m ce amide (yellow a ea). Once gene a ed, ce amide can be phospho yla ed
o o m ClP by he ac ion o ce amide kinase (Ce K). The e e sed eac ion is ca alyzed by
ClP phospha ase (CPP) o lipid phospha e phospha ases (LPP). Al ema i ely, ce amides can
be deg aded by ce amidases o o m sphingosine. Phospho yla ion o sphingosine by
sphingosine kinases (SphK) ende s SlP. The e e sed eac ion is ca alyzed by SlP
phospha ases (SPP) o lipid phospha e phospha ases (LPP). S lP lyase b eaksdown S lP o
gene a e 2- ans hexadecenal and e hanolamine phospha e.
Fig. 2. Biosyn hesis o ce amide 1-phospha e. Ce amide 1-phospha e (ClP) is mainly
syn hesized in he Golgi appa a us whe e ce amides ha a e gene a ed in he endoplasmic
e iculum (ER) a e anspo ed by ce amide ans e p o ein (CERT). Ce amides can hen be
phospho yla ed by ce amide kinase (CERK) o gene a e ClP. A ClP ans e p o ein (CPTP)
will hen anspo ClP om he Golgi o om pe inuclea memb anes, whe e ClP also esides,
o he plasma memb ane (PM) and p obably o o he o ganelles.
Fig. 3. Ce amide 1-phospha e ac ions in mammalian cells. ClP is gene a ed in acellula ly by
he ac ion o ce amide kinase (Ce K), an enzyme ha is dependen upon Ca2+ ions o ac i i y,
and ha can be s imula ed by in e leukin 1-be a (IL-1 P), o monocy e/mac ophage colony
s imula ing ac o (M-CSF). In acellula ClP can elici a a ie y o biological e ec s: 1)
s imula ion o cell p oli e a ion h ough ac i a ion o a ious kinases including c-Jun N
e minal kinase (JNK), ex acellula ly egula ed kinases (ERK), AKT (also known as p o ein
kinase B, PKB), he mammalian a ge o apamycin (mTOR), and p o ein kinase C-a (PKC-
38
a), as well as s imula ion o VEGF elease, up egula ion o e inoblas oma (Rb ), ac i a ion o
he RhoA/ROCK pa hway and s imula ion o he ansc ip ion ac o NF-kB; 2) inhibi ion o
apop osis h ough blockade o acid sphingomyelinase (A-SMase) o se ine palmi oyl ans e ase
(SPT), o h ough up egula ion o he inducible o m o ni ic oxide syn hase (iNOS)
downs eam o Ak ; 3) s imula ion o adipogenesis; 4) s imula ion o inhibi ion o in lamma o y
esponses depending on cell ype. P oin lamma o y a ge s o ClP include cPLA2 whe eas
so ne an i-in lamma o y ac ions o ClP occu h ough inhibi ion o A-SMase ac i i y. ClP can
be anspo ed o a ious o ganelles including he plasma memb ane by he ac ion o a ClP
ans e p o ein (CPTP). ClP can be eleased by cells and is p esen in plasma. Ex acellula
ClP s imula es cell mig a ion h ough a mechanism in ol ing in e ac ion wi h a pu a i e Gi
p o ein-coupled ecep o and subsequen ac i a ion o he mi ogen ac i a ed p o ein kinase
kinase (MEK)/ERK and phosphoinosi ide 3-kinase (PI3K)/Ak pa hways leading o he elease
o mac ophage chemoa ac an p o ein-1 (MCP-1). Also, ex acellula ClP p omo es glucose
up ake h ough a mechanism in ol ing ac i a ion o he PI3K/ Ak pa hway and subsequen
ansloca ion o he glucose anspo e GLUT-3 om he cy osol o he plasma memb ane. In
addi ion, ex acellula ClP can inhibi adipogenesis h ough a Gi p o ein-coupled ecep o
media ed mechanism.
39
Figu e 1
de no o pa hway
Se ine +
Palmi oyl-CoA
!SPT
3-ke osphinganine
i
Sphinganine
i
Ce S
Dihyd oce amide
Ce amide 1-phospha e
SMase pa hway
SMase GCS
Sphingomyelin E)
iDES
CERAMIDE ---;--------...... Glucosylce amide
SMS CDase ll Ce S
Sphingosine ( ( �
SphKl l
SPPILPP
Sphingosine 1-phospha e
! S1Plyase
Hexadecenal+
e hanolamine phospha e
Figu e 1
�
l
Gangliosides
Complex sphingolipids
Sal age pa hway
Figu e 2
NUCLEUS
••
•
•
•
•
•
•
•
•
•
•
•
•
•
ENDOPLASMIC
RETICULUM
GOLGI
APPARATUS
C P T P
■ ■
■ ■
__ y__�
-- ........
-........
( ;MMnññ;ñMin -,
� ijij lWij� ijij lWijij "/'
,....,;
............ __
,
.... ______
_
■
•
■
�-----....
,, ....
,
" '
' OTHER '
I '
,' ORGANELLES
1 ? 1
1 '
■ I
' I
I
', ,
' ,;
............
____
,
Figu e 2