title: Lack of Apaf-1 expression confers resistance to cytochrome c-driven apoptosis in cardiomyocytes.
abstract: Apoptosis plays a role in cardiomyocyte death in several cardiovascular disorders. Here, we show that primary postnatal cardiomyocytes did not die upon activation of the intrinsic (cytochrome c-dependent) apoptotic pathway. Release of cytochrome c from mitochondria to the cytosol occurred, but did not activate the effector phase of apoptosis. Myocardial cells did not express apoptotic protease-activating factor-1 (Apaf-1), the allosteric activator of caspase-9 acting downstream of cytochrome c release. Forced expression of Apaf-1 restored the competence to complete the cytochrome c-induced apoptotic program and this effect was prevented by overexpression of Bcl-X(L). However, cardiomyocytes were able to enter the apoptotic program when it was initiated by activation of death receptors, as observed during serum deprivation and metabolic inhibition. Our results indicate that regulation of Apaf-1 expression may be a new regulatory mechanism developed in postmitotic cells in order to prevent irreversible commitment to die after release of cytochrome c.
authors.affiliation: Departament de Recerca, Hospital Universitari Arnau de Vilanova, Lleida, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Sanchis
authors.forename: M
authors.initials: M
authors.lastname: Mayorga
authors.forename: M
authors.initials: M
authors.lastname: Ballester
authors.forename: J X
authors.initials: JX
authors.lastname: Comella
mesh_terms: D000818:Animals; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D045304:Cytochromes c / Q000378:metabolism*; D053938:DNA Fragmentation; D005947:Glucose / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019311:Staurosporine / Q000633:toxicity
chemical_list: C506594:Apaf1 protein, rat; D053477:Apoptotic Protease-Activating Factor 1; D016895:Culture Media, Serum-Free; D011506:Proteins; D045304:Cytochromes c; D019311:Staurosporine; D005947:Glucose