Glycoprotein 130 regulates cardiac myocyte survival in doxorubicin-induced apoptosis through phosphatidylinositol 3-kinase/Akt phosphorylation and Bcl-xL/caspase-3 interaction.
BACKGROUND
We recently reported that the activation of glycoprotein (gp) 130 by leukemia inhibitory factor (LIF) upregulates Bcl-xL and exerts antiapoptotic effects in cardiac myocytes. In addition, LIF induces activation of phosphatidylinositol (PI) 3-kinase and Akt, which are known to be required for cell survival. However, their regulatory roles in cell death remain unknown.


RESULTS
We investigated the fate of these proteins and the cytoprotective effects of LIF on doxorubicin (DOX)-induced apoptosis in cultured neonatal rat cardiac myocytes. Myocyte apoptosis increased significantly in DOX-treated cells but was significantly reduced by LIF pretreatment. The kinase activities of PI 3-kinase and Akt declined below basal levels but were partially recovered with LIF. Moreover, DOX-induced caspase-3 activation and decrease in Bcl-xL abundance are completely inhibited by LIF and caspase inhibitor. LIF phosphorylates Bad through PI 3-kinase and reduces the heterodimerization of Bad with Bcl-xL. Adenovirus transfer of the constitutively active form of Akt to cardiac myocytes restored cardiac myocyte survival after DOX treatment. Conversely, the dominant-negative form of Akt inhibited LIF-induced increase in cell viability and suppression of caspase-9 activation.


CONCLUSIONS
Activation of gp130 inhibits DOX-induced cell death in cardiac myocytes, resulting in the restoration of PI 3-kinase/Akt activities and in the inactivation of caspase-3, leading to facilitation of the protective function of Bcl-xL.
Negoro
S
S
Department of Molecular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Oh
H
H
Tone
E
E
Kunisada
K
K
Fujio
Y
Y
Walsh
K
K
Kishimoto
T
T
Yamauchi-Takihara
K
K
D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D050822:Cytokine Receptor gp130; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004798:Enzymes / Q000378:metabolism*; D006131:Growth Inhibitors / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008222:Lymphokines / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018121:Receptors, Cytokine / Q000378:metabolism; D053606:Receptors, OSM-LIF; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D015703:Antigens, CD; D002352:Carrier Proteins; D053148:Caspase 3; D020169:Caspases; D050822:Cytokine Receptor gp130; D004317:Doxorubicin; D004798:Enzymes; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008222:Lymphokines; D008562:Membrane Glycoproteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D018121:Receptors, Cytokine; D053606:Receptors, OSM-LIF; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C494821:Bad protein, rat; C494813:Bcl2l1 protein, rat; C494201:Il6st protein, rat; C507842:Lifr protein, rat; C494920:Akt1 protein, rat; C505410:Casp3 protein, rat