title: Globular adiponectin, acting via AdipoR1/APPL1, protects H9c2 cells from hypoxia/reoxygenation-induced apoptosis.
abstract: Cardiomyocyte apoptosis is an important remodeling event contributing to heart failure and adiponectin may mediate cardioprotective effects at least in part via attenuating apoptosis. Here we used hypoxia-reoxygenation (H/R) induced apoptosis in H9c2 cells to examine the effect of adiponectin and cellular mechanisms of action. We first used TUNEL labeling in combination with laser scanning cytometry to demonstrate that adiponectin prevented H/R-induced DNA fragmentation. The anti-apoptotic effect of adiponectin was also verified via attenuation of H/R-induced phosphatidylserine exposure using annexin V binding. H/R-induced apoptosis via the mitochondrial-mediated intrinsic pathway of apoptosis as assessed by cytochrome c release into cytosol and caspase-3 activation, both of which were attenuated by adiponectin. Mechanistically, we demonstrated that adiponectin enhanced anti-oxidative potential in these cells which led to attenuation of the increase in intracellular reactive oxygen species (ROS) caused by H/R. To further address the mechanism of adiponctins anti-apoptotic effects we used siRNA to efficiently knockdown adiponectin receptor (AdipoR1) expression and found that this attenuated the protective effects of adiponectin on ROS production and caspase 3 activity. Knockdown of APPL1, an important intracellular binding partner for AdipoR, also significantly reduced the ability of adiponectin to prevent H/R-induced ROS generation and caspase 3 activity. In summary, H/R-induced ROS generation and activation of the intrinsic apoptotic pathway was prevented by adiponectin via AdipoR1/APPL1 signaling and increased anti-oxidant potential.
authors.affiliation: Department of Biology, York University, Toronto, Canada.
authors.forename: Min
authors.initials: M
authors.lastname: Park
authors.forename: ByungSoo
authors.initials: B
authors.lastname: Youn
authors.forename: Xi-long
authors.initials: XL
authors.lastname: Zheng
authors.forename: Donghai
authors.initials: D
authors.lastname: Wu
authors.forename: Aimin
authors.initials: A
authors.lastname: Xu
authors.forename: Gary
authors.initials: G
authors.lastname: Sweeney
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D052242:Adiponectin / Q000494:pharmacology*; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D054419:Receptors, Adiponectin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015427:Reperfusion Injury / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D052242:Adiponectin; D017304:Annexin A5; D000975:Antioxidants; C515694:Appl1 protein, rat; D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D054419:Receptors, Adiponectin; C504339:adiponectin receptor 1, rat; D045304:Cytochromes c; D053148:Caspase 3; D010100:Oxygen