Annexin V/β5 Integrin Interactions Regulate Apoptosis of Growth Plate Chondrocytes

Apoptosis of terminally differentiated chondrocytes allows the replacement of growth plate cartilage by bone. Despite its importance, little is known about the regulation of chondrocyte apoptosis. We show that overexpression of annexin V, which binds to the cytoplasmic domain of β5 integrin and protein kinase C α (PKCα), stimulates apoptotic events in hypertrophic growth plate chondrocytes. To determine whether the balance between the interactions of annexin V/β5 integrin and annexin V/active PKCα play a role in the regulation of terminally differentiated growth plate chondrocyte apoptosis, a peptide mimic of annexin V (Penetratin (Pen)-VVISYSMPD) that binds to β5 integrin but not to PKCα was used. This peptide stimulated apoptotic events in growth plate chondrocytes. Suppression of annexin V expression using small interfering ribonucleic acid decreased caspase-3 activity and increased cell viability in Pen-VVISYSMPD-treated growth plate chondrocytes. An activator of PKC resulted in a further decrease of cell viability and further increase of caspase-3 activity in Pen-VVISYSMPD-treated growth plate chondrocytes, whereas inhibitors of PKCα led to an increase of cell viability and decrease of caspase-3 activity of Pen-VVISYSMPD-treated cells. These findings suggest that binding of annexin V to active PKCα stimulates apoptotic events in growth plate chondrocytes and that binding of annexin Vto β5 integrin controls these interactions and ultimately apoptosis. Apoptosis of terminally differentiated chondrocytes allows the replacement of growth plate cartilage by bone. Despite its importance, little is known about the regulation of chondrocyte apoptosis. We show that overexpression of annexin V, which binds to the cytoplasmic domain of β5 integrin and protein kinase C α (PKCα), stimulates apoptotic events in hypertrophic growth plate chondrocytes. To determine whether the balance between the interactions of annexin V/β5 integrin and annexin V/active PKCα play a role in the regulation of terminally differentiated growth plate chondrocyte apoptosis, a peptide mimic of annexin V (Penetratin (Pen)-VVISYSMPD) that binds to β5 integrin but not to PKCα was used. This peptide stimulated apoptotic events in growth plate chondrocytes. Suppression of annexin V expression using small interfering ribonucleic acid decreased caspase-3 activity and increased cell viability in Pen-VVISYSMPD-treated growth plate chondrocytes. An activator of PKC resulted in a further decrease of cell viability and further increase of caspase-3 activity in Pen-VVISYSMPD-treated growth plate chondrocytes, whereas inhibitors of PKCα led to an increase of cell viability and decrease of caspase-3 activity of Pen-VVISYSMPD-treated cells. These findings suggest that binding of annexin V to active PKCα stimulates apoptotic events in growth plate chondrocytes and that binding of annexin Vto β5 integrin controls these interactions and ultimately apoptosis. During endochondral ossification, the bone structures are first cartilaginous. Chondrocytes in these growth plate cartilages undergo a series of differentiation events, including proliferation, hypertrophy, and terminal differentiation, eventually leading to the replacement of mineralized cartilage by bone. Evolving in vitro and in vivo evidence shows that the final fate of terminally differentiated growth plate chondrocytes is apoptosis (programmed cell death) (1Gibson G.J. Kohler W.J. Schaffler M.B. Dev. Dyn. 1995; 203: 468-476Crossref PubMed Scopus (123) Google Scholar, 2Hatori M. Klatte K.J. Teixeira C.C. Shapiro I.M. J. Bone Miner. Res. 1995; 10: 1960-1968Crossref PubMed Scopus (176) Google Scholar). We have demonstrated that retinoic acid treatment of growth plate chondrocytes stimulates terminal differentiation events and eventually leads to apoptosis of these cells (3Wang W. Kirsch T. J. Cell Biol. 2002; 157: 1061-1069Crossref PubMed Scopus (113) Google Scholar, 4Wang W. Xu J. Kirsch T. J. Biol. Chem. 2003; 278: 3762-3769Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar). In addition, several in vivo studies have also revealed that apoptosis is the final fate of terminally differentiated growth plate chondrocytes. For example, we and others have demonstrated that apoptosis of growth plate chondrocytes occurs in chondrocytes at the chondro-osseous junction in chicken growth plate and sternal cartilage (1Gibson G.J. Kohler W.J. Schaffler M.B. Dev. Dyn. 1995; 203: 468-476Crossref PubMed Scopus (123) Google Scholar, 5Kirsch T. Wang W. Pfander D. J. Bone Miner. Res. 2003; 18: 1872-1881Crossref PubMed Scopus (63) Google Scholar). Furthermore, mice with targeted disruptions of both alleles for the antiapoptotic protein bcl-2 have short limbs and accelerated ossification of their growth plates (6Amling M. Neff L. Tanaka S. Inoue D. Kuida K. Weir E. Philbrick W.M. Broadus A.E. Baron R. J. Cell Biol. 1997; 136: 205-213Crossref PubMed Scopus (275) Google Scholar). In addition, two chondrodysplastic conditions (parathyroid hormone-related peptide knock-out mice and activating mutations of the fibroblast growth factor receptor-3 (FGFR-3)) are associated with increased apoptosis of the growth plate chondrocytes (7Amizuka N. Henderson J.E. Hoshi K. Warshawsky H. Ozawa H. Goltzman D. Karaplis A.C. Endocrinology. 1996; 137: 5055-5067Crossref PubMed Scopus (121) Google Scholar, 8Legeai-Mallet L. Benoist-Lasselin C. Delezoide A.L. Munnich A. Bonaventure J. J. Biol. Chem. 1998; 273: 13007-13014Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar). The various differentiation events of growth plate chondrocytes, including apoptosis, are precisely regulated to allow coordinated longitudinal bone growth. A disturbance in the regulation of these events leads to growth retardation. For example, glucocorticoid treatment results in growth retardation by decreasing the proliferation rate of growth plate chondrocytes and by increasing the apoptosis rate of terminally differentiated growth plate chondrocytes (9Chrysis D. Ritzen E.M. Savendahl L. J. Endocrinol. 2003; 176: 331-337Crossref PubMed Scopus (106) Google Scholar, 10Annefeld M. Pathol. Res. Pract. 1992; 188: 649-652Crossref PubMed Scopus (26) Google Scholar). Therefore, the understanding of the mechanisms regulating the various differentiation events is highly relevant. However, very little is known about the regulation of apoptosis of growth plate chondrocytes. Recent studies have shown that annexin V, a cytosolic protein that binds to membranes in the presence of calcium, binds to the cytoplasmic domain of β5 integrin and to active protein kinase C α (PKCα) 2The abbreviations used are: PKC, protein kinase C; Pen, Penetratin; PMA, phorbol 12-myristate 13-acetate; Myr, myristoylated; RCAS-BP, Rous sarcoma virus-based expression vector; siRNA, small interfering RNA; Bis-Tris, 2-(bis(2-hydroxyethyl)amino)-2-(hydroxymethyl)propane-1,3-dioll; AnV, annexin V; siAnV, siRNA specific for AnV; DAPI, 4′,6-diamidino-2-phenylindole; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. and that these interactions play a key role in the regulation of apoptosis of endothelial cells (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 12Schlaepfer D.D. Jones H. Haigler H.T. Biochemistry. 1992; 31: 1886-1891Crossref PubMed Scopus (111) Google Scholar). Interestingly, annexin V and β5 integrin are expressed in hypertrophic and terminally differentiated growth plate chondrocytes (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, 14Hausler G. Helmreich M. Marlovits S. Egerbacher M. Calcif. Tissue Int. 2002; 71: 212-218Crossref PubMed Scopus (38) Google Scholar). Therefore, we hypothesized that the interactions among annexin V, β5 integrin, and PKCα play a role in the regulation of apoptosis of growth plate chondrocytes. To address this hypothesis, we used a peptide mimic of annexin V, which has been shown to bind to β5 integrin and induce apoptosis in endothelial cells (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar), overexpression of annexin V using a retroviral expression vector, and suppression of annexin V using small interfering RNA (siRNA), and determined cell viability, bcl-2 and bax expression, and caspase-3 activity. Reagents—The preparation and specificity of antibodies specific for annexin V were described (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar). specific for β5 integrin were The and were and phorbol 12-myristate were was were the hypertrophic of growth plate cartilage described T. Nah Shapiro I.M. M. J. Cell Biol. 1997; 137: PubMed Scopus Google Scholar). were in in and and cells were with retroviral of Rous sarcoma virus-based expression annexin V in a small cells in of for cells were in of chondrocytes were The of overexpression was by using antibodies specific for annexin V W. Xu J. Kirsch T. Cell Res. PubMed Scopus Google Scholar). For siRNA growth plate chondrocytes were with siRNA specific for annexin V using to the W. Xu J. Kirsch T. Cell Res. PubMed Scopus Google Scholar). cells were in in the presence of C and of annexin V was first an which a acid of to the of the protein and S. E. 136: PubMed Scopus Google Scholar). To the and were used to chicken using the described W. Xu J. Kirsch T. Cell Res. PubMed Scopus Google Scholar). of siRNA to V in used the siRNA to of the and siRNA were to the chicken annexin V by using a were to an to the of in the The was described W. Xu J. Kirsch T. Cell Res. PubMed Scopus Google Scholar). The were for the to annexin V protein expression in chicken to the for of growth plate chondrocytes. The of the and and and were with the were with with acid for at for with and with for cells were by Cell were with For for β5 integrin and annexin V, cells were with and with antibodies specific for β5 integrin and antibodies specific for annexin cells were with and antibodies and by For of of chicken growth were and with in for at were with and antibodies described and Cell activity was using the described W. Xu J. Kirsch T. J. Biol. Chem. 2003; 278: 3762-3769Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar). activity was to the protein in activity is expressed with caspase-3 activity of the Cell viability was determined by of the of the and determine the of annexin V in growth plate chondrocytes, cells were in of protein was to and the was to the at for and by in the were with a of were with antibodies and and the was by are and between was using the are in the The β5 integrin was expressed in hypertrophic growth plate cartilage revealed that cells in were with antibodies specific for the β5 integrin whereas the of growth plate cartilage for and β5 integrin was in the whereas β5 integrin was V is also expressed in the hypertrophic of growth plate cartilage also T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar). annexin V, β5 integrin, and are highly expressed in the hypertrophic of growth plate A has shown that annexin V binds to the cytosolic domain of the β5 integrin (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). with antibodies specific for β5 integrin and annexin V revealed a of both in hypertrophic growth plate chondrocytes in findings an between annexin V and the β5 integrin (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). To determine the role of annexin V and its interactions with β5 integrin, we annexin V in hypertrophic growth plate chondrocytes using the retroviral expression of growth plate chondrocytes with annexin V resulted in a increase of annexin V protein expression with the expression of growth plate chondrocytes. of annexin V led to a decrease of bcl-2 expression and of bax expression and caspase-3 activity with the of cells A and To determine whether annexin V and β5 integrin interactions are in apoptotic events in growth plate chondrocytes, we used a peptide mimic of annexin V that has been shown to bind to β5 integrin and cell of endothelial cells (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). We an of the peptide by using the for Pen, a peptide that are of the of the protein has and is of the and to the cytoplasmic D. G. A. J. Biol. Chem. Full Text PDF PubMed Google Scholar). We the peptide mimic of annexin V a peptide to and a to peptide and the peptide were and in the not with these cytoplasmic of growth plate chondrocytes with for resulted in a decreased expression of the antiapoptotic factor bcl-2 and an increased expression of the apoptotic factor bax with the expression of cells with the peptide expression of bcl-2 and bax cells of growth plate chondrocytes with for led to a increase of caspase-3 activity with cells cells with and bax expression and caspase-3 activity of growth plate chondrocytes. expression of bcl-2 and bax was using in growth plate chondrocytes a treatment a apoptosis was determined by caspase-3 activity a treatment with the a with annexin peptide with resulted in of expression of bax and caspase-3 activity and of bcl-2 expression with the in cells. were of caspase-3 and were expressed we determined whether and β5 integrin are to induce apoptotic events in growth plate chondrocytes whether annexin V is also Therefore, we annexin V expression in Pen-VVISYSMPD-treated growth plate chondrocytes using siRNA and cell viability and caspase-3 activity. annexin siRNA, annexin V expression was in hypertrophic growth plate chondrocytes V expression was by treatment the cell viability to The peptide not cell viability cells with siRNA specific for annexin V treatment with and with annexin siRNA also not cell viability siAnV, However, suppression of annexin V expression led to an increase of cell viability in Pen-VVISYSMPD-treated growth plate chondrocytes viability by and caspase-3 activity of Pen-VVISYSMPD-treated annexin and and and Pen-VVISYSMPD-treated growth plate chondrocytes. treatment cell viability and increased caspase-3 activity with the in cells. However, annexin siRNA the of cell viability and caspase-3 activity were and were expressed treatment resulted in increase of caspase-3 activity in growth plate chondrocytes with the activity of cells activity was decreased in Pen-VVISYSMPD-treated cells with annexin siRNA with the in Pen-VVISYSMPD-treated cells of growth plate chondrocytes with annexin siRNA, treatment with treatment with and with annexin siRNA caspase-3 activity siAnV, V has been shown not to bind to the cytoplasmic domain of the β5 integrin but also to bind to active PKCα (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 12Schlaepfer D.D. Jones H. Haigler H.T. Biochemistry. 1992; 31: 1886-1891Crossref PubMed Scopus (111) Google Scholar). of annexin V to active PKCα PKCα activity D.D. Jones H. Haigler H.T. Biochemistry. 1992; 31: 1886-1891Crossref PubMed Scopus (111) Google Scholar, B. T. D. J. 1995; PubMed Scopus Google Scholar). active PKCα has been shown to in cell of chondrocytes J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar), we whether of PKCα annexin V annexin V/β5 integrin interactions play a role in apoptosis of growth plate chondrocytes using an activator of PKC inhibitors of PKC PKC inhibitors of growth plate chondrocytes with PMA, not cell viability caspase-3 activity with cell viability and caspase-3 activity of cells A and PMA, with and also not cell viability caspase-3 activity A and further cell viability of Pen-VVISYSMPD-treated cells for Pen-VVISYSMPD-treated cells to for and whereas increased cell viability of Pen-VVISYSMPD-treated cells viability in and cells with viability in Pen-VVISYSMPD-treated results were for caspase-3 activity. and treatment further increased caspase-3 activity with the activity in Pen-VVISYSMPD-treated cells. the with and decreased caspase-3 activity to to of cells. we whether PKC regulation by annexin V/β5 integrin interactions is specific for We growth plate chondrocytes with and for for PKC In the of not cell and viability with the and viability of and However, treatment in the of resulted in a decrease of growth plate chondrocyte viability shown treatment of growth plate chondrocytes with resulted in a of cells and a decrease of growth plate chondrocyte viability with cells cells a cells and Pen-VVISYSMPD-treated growth plate chondrocytes a to cells In addition, led to an increase of cell viability of Pen-VVISYSMPD-treated growth plate chondrocytes resulted in a further decrease of cell viability of Pen-VVISYSMPD-treated growth plate chondrocytes In this we evidence that the balance between annexin V/β5 integrin and annexin interactions a role in the regulation of growth plate chondrocyte apoptosis. Apoptosis is the final fate of terminally differentiated growth plate chondrocytes and is for endochondral bone M. Klatte K.J. Teixeira C.C. Shapiro I.M. J. Bone Miner. Res. 1995; 10: 1960-1968Crossref PubMed Scopus (176) Google Scholar, G. Res. 1998; PubMed Scopus Google Scholar). of apoptosis in growth plate cartilage results in bone For example, bcl-2 knock-out mice show accelerated chondrocyte differentiation and apoptosis, in accelerated endochondral bone and short of these mice (6Amling M. Neff L. Tanaka S. Inoue D. Kuida K. Weir E. Philbrick W.M. Broadus A.E. Baron R. J. Cell Biol. 1997; 136: 205-213Crossref PubMed Scopus (275) Google Scholar). results show that a peptide mimic of annexin V that binds to β5 integrin but not to PKCα (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google stimulates apoptotic events in hypertrophic growth plate chondrocytes. overexpression of annexin V in hypertrophic growth plate chondrocytes increased caspase-3 activity and the bax expression and decreased expression of the antiapoptotic bcl-2 that expression of annexin V in growth plate chondrocytes results in apoptosis of these cells. the suppression of annexin V in hypertrophic growth plate chondrocytes using siRNA resulted in an increase of cell viability and a decrease of caspase-3 activity in Pen-VVISYSMPD-treated growth plate chondrocytes, further that both the interactions between β5 integrin and annexin V its peptide and the interactions between annexin V and PKCα are for the regulation of growth plate chondrocyte apoptosis. V and β5 integrin are expressed by hypertrophic and terminally differentiated chondrocytes in growth plate cartilage (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, 14Hausler G. Helmreich M. Marlovits S. Egerbacher M. Calcif. Tissue Int. 2002; 71: 212-218Crossref PubMed Scopus (38) Google Scholar). Furthermore, we have shown that retinoic terminal differentiation and apoptotic events in growth plate chondrocytes are by of annexin V, annexin and annexin expression (3Wang W. Kirsch T. J. Cell Biol. 2002; 157: 1061-1069Crossref PubMed Scopus (113) Google Scholar, 4Wang W. Xu J. Kirsch T. J. Biol. Chem. 2003; 278: 3762-3769Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar). annexin V terminal differentiation events and apoptosis of growth plate events are regulated by the interactions of a of including of cytosolic V, and in the of terminally differentiated growth plate chondrocytes, leading to the of these cells. These in cytoplasmic a series of events, including of expression of terminal differentiation and of and events W. Xu J. Kirsch T. J. Biol. Chem. 2003; 278: 3762-3769Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar). The shows that annexin V apoptosis not by but also its interactions with β5 integrin and events are for regulation of apoptosis The of results in an of cell and also 4Wang W. Xu J. Kirsch T. J. Biol. Chem. 2003; 278: 3762-3769Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar). the peptide mimic of annexin V stimulates the β5 overexpression of annexin V stimulates both the cytosolic and the β5 An of PKC decreased caspase-3 activity and increased cell viability of growth plate chondrocytes with whereas treatment of cells with and an activator of PKC further increased caspase-3 activity and decreased cell viability with the of Pen-VVISYSMPD-treated cells. This was specific for PKCα in that a specific of PKCα increased viability of Pen-VVISYSMPD-treated growth plate chondrocytes. A that binds to β5 integrin but not to In annexin V binds to both β5 integrin and PKCα (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). to β5 integrin with binding of annexin V to active PKCα (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Furthermore, studies have shown that annexin V binds to the active of PKCα but not to the of annexin V to active PKCα results in annexin PKC D.D. Jones H. Haigler H.T. Biochemistry. 1992; 31: 1886-1891Crossref PubMed Scopus (111) Google Scholar, B. T. D. J. 1995; PubMed Scopus Google Scholar, T. D. E. J. 1998; PubMed Scopus Google Scholar). Therefore, the In the presence of β5 integrin and of annexin V, of annexin V is integrin and not to in an active PKCα and events by PKCα In the presence of of annexin V, in terminally differentiated growth plate chondrocytes, of annexin V are to bind to both β5 integrin and active in an annexin of PKCα and its events In the presence of of annexin V, annexin of PKCα and cell by which binds to β5 integrin but not The of with β5 integrin annexin V β5 integrin annexin V to bind to active PKCα The presence of an activator of PKCα further decreased cell viability of Pen-VVISYSMPD-treated growth plate chondrocytes has been shown to binding of annexin V to active PKCα also M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). the inhibitors of PKCα binding of annexin V to PKCα in the presence of of annexin V annexin of PKCα and cell Interestingly, active PKCα has been in cell in a of cell C. PubMed Scopus Google Scholar, S. J. 2002; PubMed Scopus Google Scholar). findings that suppression of annexin V expression in growth plate chondrocytes increased cell viability and decreased caspase-3 activity in Pen-VVISYSMPD-treated cells suggest that active PKCα also cell in chondrocytes and that of PKCα by annexin V the interactions among annexin V, β5 integrin, and PKCα are for the of apoptotic events in growth plate chondrocytes. of PKCα has been shown to play an role in apoptosis Apoptosis of is associated with a decrease in bcl-2 expression and an increase in bax expression, which is to the findings of in which PKCα in growth plate chondrocytes was by annexin V, in decreased expression of bcl-2 and increased expression of bax C. PubMed Scopus Google Scholar). findings have shown that PKCα in cells proliferation and apoptosis and that these were also by of bcl-2 and bax expression M. B. T. J. H. J. Res. Google Scholar). to the findings of a that apoptosis of endothelial cells by a (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Therefore, is to that V/β5 integrin interactions play a role not in the regulation of growth plate chondrocyte apoptosis but also in the regulation of apoptosis of cell have been shown to play in cell differentiation and to antiapoptotic the cell and specific that is findings that the interactions among annexin V, β5 integrin, and active PKCα play a role in growth plate chondrocytes suggest that not of PKC but also the of PKC a role in whether the interactions among annexin V, β5 integrin, and active PKCα were to cell of growth plate chondrocytes, a specific of decreased cell of and Pen-VVISYSMPD-treated growth plate chondrocytes, that an role in cell of hypertrophic growth plate chondrocytes of the role of β5 These findings are with findings that of is for apoptosis of chondrocytes and that of activity is for the apoptosis of various cell J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, S. J. L. J. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, A. A. C. G. A. PubMed Scopus (38) Google Scholar). Therefore, is that the regulation of the of various by mechanisms a role in the regulation of growth plate and chondrocyte apoptosis. is expressed in chondrocytes the growth with in and chondrocytes and decreased in terminally differentiated chondrocytes. The was for expression, with in cells and a increase hypertrophic chondrocytes. the growth the of to bax in chondrocytes in of (6Amling M. Neff L. Tanaka S. Inoue D. Kuida K. Weir E. Philbrick W.M. Broadus A.E. Baron R. J. Cell Biol. 1997; 136: 205-213Crossref PubMed Scopus (275) Google Scholar). This in the in of bax results in the apoptotic of terminally differentiated chondrocytes (1Gibson G.J. Kohler W.J. Schaffler M.B. Dev. Dyn. 1995; 203: 468-476Crossref PubMed Scopus (123) Google Scholar, 2Hatori M. Klatte K.J. Teixeira C.C. Shapiro I.M. J. Bone Miner. Res. 1995; 10: 1960-1968Crossref PubMed Scopus (176) Google Scholar, 5Kirsch T. Wang W. Pfander D. J. Bone Miner. Res. 2003; 18: 1872-1881Crossref PubMed Scopus (63) Google Scholar). findings show that annexin V/β5 interactions in the of bcl-2 and bax expression in of that annexin V/β5 interactions apoptosis of growth plate chondrocytes by the in of We and others have shown that chondrocytes in cartilage undergo differentiation events to of growth plate chondrocytes, in terminal differentiation of chondrocytes (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, G. J. Google Scholar). Interestingly, these cells also annexin V and β5 integrin (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, K. J. K. J. 1998; PubMed Scopus Google Scholar). Furthermore, several studies have shown that chondrocytes in cartilage undergo apoptotic (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, R. E. 1998; PubMed Scopus Google Scholar, N. C. K. G. J. Res. PubMed Scopus Google Scholar, S. K. D. M. 1998; PubMed Scopus Google Scholar, L. C. Biol. 1998; PubMed Scopus Google Scholar). Therefore, is that annexin V, β5 integrin, and PKCα are in the regulation of apoptosis of chondrocytes in by a to that described in the for growth plate chondrocytes. Interestingly, has been that apoptosis of chondrocytes the of PKCα and with the findings of J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). β5 integrin is expressed by various cell A expression of β5 integrin in cartilages and that β5 integrin is a key integrin in bone L. S. K. M. L. A. S. M. M. Cell 8: PubMed Scopus Google Scholar). However, mice β5 integrin show M. J. D. Mol. Cell Biol. 2000; PubMed Scopus Google Scholar). is that integrin, for the of β5 a of in mice also including the of the the of the For example, two of annexin mice were shows a whereas the has a M. M. G. H. G. J. H. D. E. S. A. PubMed Scopus Google Scholar, C. N. S. J. B. K. K. R. R. Mol. Cell Biol. PubMed Scopus Google Scholar). In we evidence that the among annexin V, β5 integrin, and PKCα interactions regulation of apoptosis of growth plate chondrocytes. findings that a of annexin V is to with β5 integrin and PKCα and that the interactions of annexin V with both β5 integrin and PKCα are for the of apoptosis of growth plate chondrocytes. the of annexin V in growth plate chondrocytes to with β5 integrin PKCα by overexpression of annexin V by the annexin peptide stimulated apoptotic events in growth plate chondrocytes, whereas annexin V expression apoptotic events in growth plate chondrocytes in the presence of the annexin V peptide mimic cells to undergo apoptosis by a annexin V/β5 integrin and PKC (11Cardo-Vila M. Arap W. Pasqualini R. Mol. Cell. 2003; 11: 1151-1162Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). that annexin V and β5 integrin are also expressed in cartilage (13Kirsch T. Swoboda B. Nah H.-D. Osteoarthr. Cartilage. 2000; 8: 294-302Abstract Full Text PDF PubMed Scopus (180) Google Scholar, K. J. K. J. 1998; PubMed Scopus Google Scholar, J. M. S. H. J. PubMed Scopus Google and that of PKCα to in chondrocyte apoptosis J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar), is that a leads to cell of chondrocytes.