Extracellular S100A1 Protein Inhibits Apoptosis in Ventricular Cardiomyocytes via Activation of the Extracellular Signal-regulated Protein Kinase 1/2 (ERK1/2)

Abstract

S100A1 is a Ca2+-binding protein of the EF-hand type that belongs to the S100 protein family. It is specifically expressed in the myocardium at high levels and is considered to be an important regulator of cardiac contractility. Because the S100A1 protein is released into the extracellular space during ischemic myocardial injury, we examined the cardioprotective potential of the extracellular S100A1 protein on ventricular cardiomyocytes in vitro. In this report we show that extracellularly added S100A1 protein is endocytosed into the endosomal compartment of neonatal ventricular cardiomyocytes via a Ca2+-dependent clathrin-mediated process. S100A1 uptake protects neonatal ventricular cardiomyocytes from 2-deoxyglucose and oxidative stress-induced apoptosis in vitro. S100A1-mediated anti-apoptotic effects involve specific activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) pro-survival pathway, including activation of phospholipase C, protein kinase C, mitogen-activated protein kinase kinase 1, and ERK1/2. In contrast, neither transsarcolemmal Ca2+ influx via the L-type channel nor protein kinase A activity seems to take part in the S100A1-mediated signaling pathway. In conclusion, this study provides evidence for the S100A1 protein serving as a novel cardioprotective factor in vitro. These findings warrant speculation that injury-dependent release of the S100A1 protein from cardiomyocytes may serve as an intrinsic mechanism to promote survival of the myocardium in vivo. S100A1 is a Ca2+-binding protein of the EF-hand type that belongs to the S100 protein family. It is specifically expressed in the myocardium at high levels and is considered to be an important regulator of cardiac contractility. Because the S100A1 protein is released into the extracellular space during ischemic myocardial injury, we examined the cardioprotective potential of the extracellular S100A1 protein on ventricular cardiomyocytes in vitro. In this report we show that extracellularly added S100A1 protein is endocytosed into the endosomal compartment of neonatal ventricular cardiomyocytes via a Ca2+-dependent clathrin-mediated process. S100A1 uptake protects neonatal ventricular cardiomyocytes from 2-deoxyglucose and oxidative stress-induced apoptosis in vitro. S100A1-mediated anti-apoptotic effects involve specific activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) pro-survival pathway, including activation of phospholipase C, protein kinase C, mitogen-activated protein kinase kinase 1, and ERK1/2. In contrast, neither transsarcolemmal Ca2+ influx via the L-type channel nor protein kinase A activity seems to take part in the S100A1-mediated signaling pathway. In conclusion, this study provides evidence for the S100A1 protein serving as a novel cardioprotective factor in vitro. These findings warrant speculation that injury-dependent release of the S100A1 protein from cardiomyocytes may serve as an intrinsic mechanism to promote survival of the myocardium in vivo. S100A1, a low molecular weight (Mr 10,000) Ca2+-binding protein belongs to a multigenic family (21 members) of nonubiquitous Ca2+-modulated proteins to form an important sub-class of EF-hand proteins. Importantly, S100 proteins exhibit cell- and tissue-specific expression and have been linked to Ca2+-dependent regulation of a variety of S100 isoform-specific intracellular activities such as protein phosphorylation, enzyme activity, cell proliferation and differentiation, dynamics of cytoskeletal constituents, structural organization of membranes, intracellular Ca2+-homeostasis, and inflammation (for reviews, see Refs. 1Zimmer D.B. Cornwall E.H. Landar A. Song W. Brain Res. Bull. 1995; 37: 417-429Crossref PubMed Scopus (816) Google Scholar, 2Heizmann C.W. Cox J.A. Biometals. 1998; 11: 383-397Crossref PubMed Scopus (260) Google Scholar, 3Donato R. Microsc. Res. Tech. 2003; 60: 540-551Crossref PubMed Scopus (815) Google Scholar). S100A1 is the most abundant S100 protein isoform in striated muscle and has been identified as a novel positive inotropic intracellular regulator of cardiac as well as skeletal muscle Ca2+-homeostasis and contractility (4Most P. Bernotat J. Ehlermann P. Pleger S.T. Borries M. Niroomand F. Pieske B. Janssen P.M. Eschenhagen T. Karczewski P. Smith G.L. Koch W.J. Katus H.A. Remppis A. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: 13889-13894Crossref PubMed Scopus (124) Google Scholar, 5Most P. Remppis A. Pleger S.T. Löffler E. Ehlermann P. Bernotat J. Kleuss C. Heierhorst J. Ruiz P. Witt H. Karczewski P. Mao L. Rockman H.A. Duncan S.J. Katus H.A. Koch W.J. J. Biol. Chem. 2003; 278: 33809-33817Abstract Full Text Full Text PDF PubMed Scopus (112) Google Scholar, 6Most P. Remppis A. Weber C. Bernotat J. Ehlermann P. Pleger S.T. Kirsch W. Weber M. Uttenweiler D. Smith G.L. Katus H.A. Fink R.H. J. Biol. Chem. 2003; 278: 26356-26364Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar, 7Remppis A. Most P. Löffler E. Ehlermann P. Bernotat J. Pleger S.T. Börries M. Repper M. Fischer J. Koch W.J. Smith G.L. Katus H.A. Basic Res. Cardiol. 2002; 97: I56-I62Crossref PubMed Google Scholar, 8Du X.J. Cole T.J. Tenis N. Gao X.M. Kontgen F. Kemp B.E. Heierhorst J. Mol. Cell. Biol. 2002; 22: 2821-2829Crossref PubMed Scopus (105) Google Scholar). However, growing evidence indicates that members of the S100 protein family also exert extracellular effects on their target cells (3Donato R. Microsc. Res. Tech. 2003; 60: 540-551Crossref PubMed Scopus (815) Google Scholar). Although S100 proteins apparently lack the signaling sequences required for secretion, some S100 isoforms seem to follow secretory pathways that involve neither the classical endoplasmic reticulum/Golgi nor the alternative interleukin-1-like route (9Rammes A. Roth J. Goebeler M. Klempt M. Hartmann M. Sorg C. J. Biol. Chem. 1997; 272: 9496-9502Abstract Full Text Full Text PDF PubMed Scopus (478) Google Scholar). For instance, S100A8 and S100A9, expressed at high concentrations by myelomonocytic cells, are secreted by a novel tubulin-dependent pathway and then exert important roles in the regulation of inflammatory processes (9Rammes A. Roth J. Goebeler M. Klempt M. Hartmann M. Sorg C. J. Biol. Chem. 1997; 272: 9496-9502Abstract Full Text Full Text PDF PubMed Scopus (478) Google Scholar). Similarly, extracellular functions for S100B, which is secreted by astrocytes, have been described extensively (10Davey G.E. Murmann P. Heizmann C.W. J. Biol. Chem. 2001; 276: 30819-30826Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar). After secretion, S100B appears to exert both trophic and pro-survival effects on neurons via activation of the Ras/mitogen-activated protein (MAP) 1The abbreviations used are: MAPmitogen-activated proteinMAPKMAP kinaseERK1/2extracellular signal-regulated kinase 1/2MEKMAPK/ERK kinase[CA2+]eextracellular Ca2+CPZchlorpromazine2-DOG2-deoxyglucoseMDCmonodansylcadaverineMTT3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromideMyrmyristoylatedNVCMneonatal ventricular cardiomyocytePBSphosphate-buffered salinePKAprotein kinase APKCprotein kinase CPLCphospholipase CRAGEreceptor for advanced glycosylated end productsRh-S100A1rhodamine-conjugated recombinant S100A1 proteinSAPK/JNKstress-activated protein kinase/c-Jun NH2-terminal kinase. kinase pathway (11Huttunen H.J. Kuja-Panula J. Sorci G. Agneletti A.L. Donato R. Rauvala H. J. Biol. Chem. 2000; 275: 40096-40105Abstract Full Text Full Text PDF PubMed Scopus (513) Google Scholar, 12Alexanian A.R. Bamburg J.R. FASEB J. 1999; 13: 1611-1620Crossref PubMed Scopus (50) Google Scholar). Neurotrophic effects have also been reported for extracellular S100A4 and S100A12 protein based on the activation of the extracellular signal-regulated protein kinase (ERK1/2) signaling pathway (13Novitskaya V. Grigorian M. Kriajevska M. Tarabykina S. Bronstein I. Berezin V. Bock E. Lukanidin E. J. Biol. Chem. 2000; 275: 41278-41286Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar, 14Mikkelsen S.E. Novitskaya V. Kriajevska M. Berezin V. Bock E. Norrild B. Lukanidin E. J. Neurochem. 2001; 79: 767-776Crossref PubMed Scopus (36) Google Scholar). mitogen-activated protein MAP kinase extracellular signal-regulated kinase 1/2 MAPK/ERK kinase extracellular Ca2+ chlorpromazine 2-deoxyglucose monodansylcadaverine 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide myristoylated neonatal ventricular cardiomyocyte phosphate-buffered saline protein kinase A protein kinase C phospholipase C receptor for advanced glycosylated end products rhodamine-conjugated recombinant S100A1 protein stress-activated protein kinase/c-Jun NH2-terminal kinase. It has been shown that the S100A1 protein is released into the extracellular space in considerable amounts during ischemic myocardial injury via an unknown mechanism (15Kiewitz R. Acklin C. Minder E. Huber P.R. Schafer B.W. Heizmann C.W. Biochem. Biophys. Res. Commun. 2000; 274: 865-871Crossref PubMed Scopus (48) Google Scholar). Based on these observations, we raised the hypothesis that the extracellular S100A1 protein may exert protective effects on myocardial cells. To address this question, the current study focuses on the characterization of the extracellular effects of S100A1 protein on cardiac myocytes and related molecular mechanisms in vitro. Indeed, our study identifies the S100A1 protein as a novel cardioprotective factor, because we could demonstrate for the first time that the extracellular S100A1 protein can protect cardiomyocytes from apoptosis based on Ca2+-dependent clathrin-mediated endocytotic uptake resulting in a specific activation of the pro-survival ERK1/2 signaling pathway. Reagents—Monodansylcadaverine (M-4008), chlorpromazine (C-8138), and verapamil (V-4629) were purchased from Sigma, whereas myristoylated (Myr) protein kinase A (PKA) inhibitor (Myr-PKI; catalog number 476485), calphostin-c (catalog number 208725), U-73122 (catalog number 662035), and PD98095 (catalog number 513000) were obtained from Calbiochem. Myr-FRCRCF was custom-made by Eurogentec (Belgium) as described previously (16Convery M.K. Levi A.J. Khananshvili D. Hancox J.C. Pfluegers Arch. Eur. J. Physiol. 1998; 436: 581-590Crossref PubMed Scopus (14) Google Scholar, 17Hobai I.A. Khananshvili D. Levi A.J. Pfluegers Arch. Eur. J. Physiol. 1997; 433: 455-463Crossref PubMed Scopus (35) Google Scholar). Anti-receptor for advanced glycosylated end products (anti-RAGE) antibody was obtained from Chemicon (catalog number MAB5328). Expression and Purification of Human Recombinant S100A1 Protein—Expression and purification of the human recombinant S100A1 protein in Escherichia coli were performed as described previously (6Most P. Remppis A. Weber C. Bernotat J. Ehlermann P. Pleger S.T. Kirsch W. Weber M. Uttenweiler D. Smith G.L. Katus H.A. Fink R.H. J. Biol. Chem. 2003; 278: 26356-26364Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar). After dialysis against PBS (pH 7.4), aliquots of purified S100A1 were stored at -80 °C. Coupling of S100A1 was by of neonatal ventricular cardiomyocytes was performed as described previously A. in and Scholar). were for on in and at in a To were in 2-deoxyglucose for an were human recombinant S100A1 and on were as PBS (pH 7.4), in and in PBS were in for to cells were of the antibody for in the were and then the antibody was added for After were in were obtained a on a were by and For an a was were and of cells was by cells on were for by a number of at cells were release and activity were by catalog number and catalog number as by the based on the of was purchased from and to the and specific were performed to protein levels of MAP catalog number catalog number catalog number cardiac and S100A1 protein were in PBS and the in and a of inhibitor and inhibitor To were first extensively and and then were the and by are as S.E. and a of were performed to for A of was as Ca2+-dependent of S100A1 in the of extracellularly added S100A1 protein on the of human recombinant S100A1 protein was by and the of S100A1 was by an custom-made antibody that specifically human S100A1 as described (6Most P. Remppis A. Weber C. Bernotat J. Ehlermann P. Pleger S.T. Kirsch W. Weber M. Uttenweiler D. Smith G.L. Katus H.A. Fink R.H. J. Biol. Chem. 2003; 278: 26356-26364Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar). of rhodamine-conjugated recombinant S100A1 protein for and in the of extracellular Ca2+ in a of the protein in the as shown by a of S100A1 at the of the of of an antibody the striated of a reported of S100A1 protein the R. M. M. I. Donato R. Biophys. PubMed Scopus Google protein to to the that and S100A1 proteins are in serving functions in the To the of S100A1 were concentrations of However, in these cells we uptake In to in a of protein was in cells that were in indicates that the uptake of S100A1 is on of from and cells S100A1 in the and of Ca2+ by the of S100A1 were for antibody to the of recombinant S100A1, uptake of the S100A1 protein was also for a specific the was an uptake of the protein by the could be In contrast, that have identified as a potential S100 protein intracellular uptake of S100A1 could be by a an antibody that the of the receptor (11Huttunen H.J. Kuja-Panula J. Sorci G. Agneletti A.L. Donato R. Rauvala H. J. Biol. Chem. 2000; 275: 40096-40105Abstract Full Text Full Text PDF PubMed Scopus (513) Google Scholar, S. C. W. A. C. N. A. P. T. D. J. M. J. D. Cell. 1999; 97: Full Text Full Text PDF PubMed Scopus Google of S100A1 of of and in the of Ca2+ an antibody that is specific for human of to the uptake of an antibody that cardiac that the protein in was the uptake of added in the of C, an antibody the striated for of and in the of of in the of of in the of an of and the striated for cardiomyocytes of from that were amounts of antibody uptake of extracellularly added S100A1 is by in a human S100A1 is is in the at To into the pathway of S100A1 were an antibody which is a for the uptake 2003; PubMed Scopus Google Scholar). the and that the is from that of In contrast, of an which is a for the endosomal that and are part of the endosomal compartment G. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, A. M. C. 1998; PubMed Scopus Google Scholar). To that a clathrin-mediated uptake a is in S100A1 we examined the effects of of clathrin-mediated monodansylcadaverine and chlorpromazine 2001; Full Text Full Text PDF PubMed Scopus Google Scholar, A. M. Mol. Biol. 2002; PubMed Scopus Google on the uptake of by of of cells S100A1 in the of that were an S100A1 antibody and in a of S100A1 of S100A1 in the of an of of S100A1 in of of in the of and S100A1 is an antibody whereas an antibody was used to amounts of protein in of S100A1 uptake via the clathrin-mediated pathway by and is of of in the is clathrin-mediated is by C, of the an antibody the of In conclusion, our that the extracellular S100A1 protein is and for the endosomal compartment of via a clathrin-mediated endocytotic pathway. Because apparently of the extracellular S100A1 protein in in our the S100A1 protein may be endocytosed by to be identified of the ERK1/2 by signaling proteins of the pathways in have been linked to the endosomal compartment (for see A. M. Mol. Biol. 2002; PubMed Scopus Google we endocytotic uptake of the S100A1 protein activity in For this of were that specifically the the form of the that the of S100A1 to in the of in a specific of (ERK1/2) cells. is by the of S100A1-mediated activation of ERK1/2 was In contrast, the of of and Ca2+-dependent S100A1 uptake was that of cells of S100A1 protein in the of to a time of ERK1/2 activation whereas a of concentrations of extracellular S100A1 protein in a of ERK1/2 the of endocytosed S100A1 protein and of S100A1 by monodansylcadaverine the S100A1-mediated in ERK1/2 S100A1-mediated activation of 1/2 could be by PD98095 a specific inhibitor of Witt R. J. 2000; PubMed Scopus Google Scholar, H. M. P. Biochem. J. 2000; PubMed Scopus Google of S100A1 on the signaling pathway of of from cells S100A1 in the of and specific S100A1 uptake as well as S100A1-mediated of ERK1/2 is of amounts of inhibitor PD98095 and to of show that is by whereas the levels of ERK1/2 are in a C, effects of and on S100A1-mediated activation of ERK1/2 In the of inhibitor levels of are A is by of In contrast, of by the inhibitor has on the levels of the an antibody that S100A1 is by the of and effects of transsarcolemmal Ca2+ influx on ERK1/2 of L-type and a inhibitor to a of levels in cells and cells by S100A1 uptake and S100A1-mediated activation of ERK1/2 are protein in was by levels of cardiac Because the extracellular effects of S100A4 protein on neurons on phospholipase C which has also been linked to the endosomal we the of by U-73122 on S100A1-mediated ERK1/2 activation (13Novitskaya V. Grigorian M. Kriajevska M. Tarabykina S. Bronstein I. Berezin V. Bock E. Lukanidin E. J. Biol. Chem. 2000; 275: 41278-41286Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar, A. M. Mol. Biol. 2002; PubMed Scopus Google Scholar). in appears that the of the of ERK1/2 Because activation of is to protein kinase C activity, we S100A1-mediated of ERK1/2 activity activation of in the of calphostin-c a inhibitor of (13Novitskaya V. Grigorian M. Kriajevska M. Tarabykina S. Bronstein I. Berezin V. Bock E. Lukanidin E. J. Biol. Chem. 2000; 275: 41278-41286Abstract Full Text Full Text PDF PubMed Scopus (145) Google of ERK1/2 was Because activation of protein kinase (PKA) has also been linked to ERK1/2 we the of on ERK1/2 activation by a specific inhibitor E. C. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). However, of the inhibitor for S100A1-mediated of ERK1/2 activity that the of the ERK1/2 signaling pathway by S100A1 involve Ca2+ influx has been shown to be of ERK1/2 signaling E. C. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). Because the of the S100A1 protein to cardiomyocytes has been shown to L-type activity and Ca2+ influx M. Remppis A. P. W. Most P. J. Katus H.A. Eur. J. 2002; Google we the of extracellularly added S100A1 protein on ERK1/2 signaling in to of transsarcolemmal Ca2+ For this the receptor was verapamil and the was a specific Myr-FRCRCF In both the the of ERK1/2 in cells as well as in cardiomyocytes the and S100A1-mediated activation of ERK1/2 S100A1 our the that the endocytosed S100A1 protein specifically ERK1/2 activity via the pathway. In contrast, and transsarcolemmal Ca2+ influx to be in the S100A1-mediated activation of ERK1/2. S100A1 via ERK1/2 that have that ERK1/2 activation is from apoptosis in cardiomyocytes Witt R. J. 2000; PubMed Scopus Google Scholar, R. I. T. S. M. I. J. 1997; PubMed Scopus Google Scholar, S. T. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, P. W. R. R. 2001; PubMed Scopus Google Scholar, M. A.R. D. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google to ERK1/2 signaling may exert cardioprotective effects on To the of S100A1 provides from were in 2-deoxyglucose for as described previously Witt R. J. 2000; PubMed Scopus Google and in the inhibitor of in in to cells in of S100A1 to in cell A and is were in and the cells a In the of S100A1 the of was and the cell is to that of cells in from apoptosis was in the of the inhibitor PD98095 of was by and of S100A1 protein the of cells cell were However, of cells in were and to the cells were S100A1 the survival of cells was the S100A1-mediated from apoptosis was by the of the inhibitor PD98095 of and activity were S100A1 was added to cells in the release and activity was by and and the S100A1-mediated from apoptosis was by the of of the inhibitor also a of activity in cells In these the of cardiomyocytes S100A1 oxidative stress-induced apoptosis by in our In these demonstrate that the of the S100A1 protein to neonatal ventricular cardiomyocytes protects via the activation of ERK1/2 signaling from To the family of Ca2+-binding proteins of the EF-hand type as S100 proteins has to members that are expressed in a number of cell S100 proteins are as which are in the Ca2+-dependent regulation of a variety of activities in the cell (3Donato R. Microsc. Res. Tech. 2003; 60: 540-551Crossref PubMed Scopus (815) Google Scholar). evidence indicates that S100 secreted released into the extracellular may also exert specific effects on their target cells. For instance, extracellular S100A8 and secreted by a novel tubulin-dependent pathway have been important functions in the regulation of inflammatory processes (9Rammes A. Roth J. Goebeler M. Klempt M. Hartmann M. Sorg C. J. Biol. Chem. 1997; 272: 9496-9502Abstract Full Text Full Text PDF PubMed Scopus (478) Google Scholar). In secreted S100B, and S100A12 have been shown to exert a on neurons (11Huttunen H.J. Kuja-Panula J. Sorci G. Agneletti A.L. Donato R. Rauvala H. J. Biol. Chem. 2000; 275: 40096-40105Abstract Full Text Full Text PDF PubMed Scopus (513) Google Scholar, V. Grigorian M. Kriajevska M. Tarabykina S. Bronstein I. Berezin V. Bock E. Lukanidin E. J. Biol. Chem. 2000; 275: 41278-41286Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar, 14Mikkelsen S.E. Novitskaya V. Kriajevska M. Berezin V. Bock E. Norrild B. Lukanidin E. J. Neurochem. 2001; 79: 767-776Crossref PubMed Scopus (36) Google Scholar). In the of S100B, the trophic effects on were by an expression of the anti-apoptotic protein (11Huttunen H.J. Kuja-Panula J. Sorci G. Agneletti A.L. Donato R. Rauvala H. J. Biol. Chem. 2000; 275: 40096-40105Abstract Full Text Full Text PDF PubMed Scopus (513) Google Scholar). Because S100A1 is also released into the extracellular space ischemic myocardial injury (15Kiewitz R. Acklin C. Minder E. Huber P.R. Schafer B.W. Heizmann C.W. Biochem. Biophys. Res. Commun. 2000; 274: 865-871Crossref PubMed Scopus (48) Google we this study the of extracellular S100A1 may exert protective effects on cardiac cells. for the first evidence that the extracellular of the S100A1 protein can protect neonatal ventricular cardiomyocytes from apoptosis in via specific activation of the ERK1/2 signaling pathway. the human recombinant S100A1 protein we were to the uptake of S100A1 into the compartment of and uptake that the S100A1 protein is via a Ca2+-dependent clathrin-mediated endocytotic pathway. our that cell which has been reported to S100B (11Huttunen H.J. Kuja-Panula J. Sorci G. Agneletti A.L. Donato R. Rauvala H. J. Biol. Chem. 2000; 275: 40096-40105Abstract Full Text Full Text PDF PubMed Scopus (513) Google Scholar, S. C. W. A. C. N. A. P. T. D. J. M. J. D. Cell. 1999; 97: Full Text Full Text PDF PubMed Scopus Google seem to be in the of S100A1 in cell receptor is to be for S100A1 uptake in of the S100A1 protein into cardiomyocytes has been shown to be a in M. Remppis A. P. W. Most P. J. Katus H.A. Eur. J. 2002; Google Scholar). to the current this in is to endocytotic at the which then as and the endosomal A growing of evidence indicates that signaling proteins in receptor kinase and receptor and are in from to the and A. M. Mol. Biol. 2002; PubMed Scopus Google Scholar). In has been shown that the extracellular of the S100A4 protein the ERK1/2 signaling pathway (13Novitskaya V. Grigorian M. Kriajevska M. Tarabykina S. Bronstein I. Berezin V. Bock E. Lukanidin E. J. Biol. Chem. 2000; 275: 41278-41286Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar). our obtained from that specifically of the obtained of the signaling pathway were demonstrate that the S100A1 protein specifically ERK1/2 in cardiomyocytes both in a and a of the S100A1 protein an important for the activation of because of S100A1 both in and in the of of clathrin-mediated in a lack of ERK1/2 In contrast, in signaling such as and are specific of intracellular we could that S100A1-mediated activation of ERK1/2 signaling activation of and which have been linked to the endosomal compartment A. M. Mol. Biol. 2002; PubMed Scopus Google Scholar). A of ERK1/2 activation by has been reported previously J.C. J. Biol. 2002; PubMed Scopus Google Scholar). Based on our we have a of S100A1 in the ERK1/2 signaling by the our also evidence that Ca2+ influx by the L-type channel in the S100A1-mediated of ERK1/2 These findings are in to by which that activation of ERK1/2 Ca2+ influx L-type channel in a E. C. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). in their activity ERK1/2 whereas of on the S100A1-mediated ERK1/2 activation in In an at in in the of S100A1 evidence for activity in our these we that S100A1-mediated ERK1/2 activation a signaling pathway our the that S100A1 protein is to the endosomal compartment specifically the ERK1/2 signaling pathway. Because activation of the ERK1/2 signaling pathway by has been reported to protect cardiomyocytes from apoptosis Witt R. J. 2000; PubMed Scopus Google Scholar, R. I. T. S. M. I. J. 1997; PubMed Scopus Google Scholar, P. W. R. R. 2001; PubMed Scopus Google Scholar, M. A.R. D. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google Scholar, J. M. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google we examined S100A1 a on the of neonatal cardiomyocytes in to the Indeed, our show that the S100A1 protein the survival of cardiomyocytes in to cells at the time a release of a activity, and their In the of cardiomyocytes S100A1 oxidative stress-induced apoptosis by in our the of the S100A1 the S100A1 signaling pathway in these pro-survival are is by the of our study evidence that the of S100A1 uptake in is by ERK1/2 of the study the for the shown in which the signaling pathways in the of extracellular S100A1 on In conclusion, our study identifies the extracellular S100A1 protein as a novel factor that survival of neonatal cardiomyocytes in via activation of the kinase pathway. mechanism by which a considerable of S100A1 is released into the extracellular space during ischemic myocardial injury is Because S100 proteins are secreted by a a tubulin-dependent pathway, a mechanism for myocardial S100A1 Based on these we in S100A1 from myocardial cells promote the survival of the Because S100A1 protein levels are in A. T. Schafer B.W. P. P. Katus H.A. Heizmann C.W. Biophys. PubMed Scopus Google and S100A1 in of cardiac in X.J. Cole T.J. Tenis N. Gao X.M. Kontgen F. Kemp B.E. Heierhorst J. Mol. Cell. Biol. 2002; 22: 2821-2829Crossref PubMed Scopus (105) Google S100A1 protein may in contractility of the may also to an of cardiomyocytes to the molecular mechanism of myocardial S100A1 release is as are that into the of the cardioprotective of the S100A1 protein on cardiac cells in vivo.