AKAP150 mobilizes cPKC-dependent cardiac glucotoxicity.
Activation of conventional PKCs (cPKC) is a key signaling that directs the cardiac toxicity of hyperglycemia. AKAP150, a scaffold protein of the A-kinase anchoring proteins (AKAPs) family, is less defined regarding its capability to anchor and regulate cardiac cPKC signaling. This study was designed to investigate the role of AKAP150 in cPKC-mediated cardiac glucotoxicity. In cardiac tissues from streptozotocin-induced diabetic rats and high-glucose-treated neonatal rat cardiomyocytes, both mRNA and protein levels of AKAP150 increased significantly, and marked elevations were observed in cPKC activity and both expression and phosphorylation levels of p65 NF-κB and p47(phox). AKAP150 knockdown was established via intramyocardial injection in vivo and transfection in vitro of adenovirus carrying AKAP150-targeted shRNA. Downregulation of AKAP150 reversed diabetes-induced diastolic dysfunction as manifested by decreased left ventricular end-diastolic diameter and early/late mitral diastolic wave ratio. AKAP150 inhibition also abrogated high-glucose-induced cardiomyocyte apoptosis (TUNEL staining and annexin V/propidium iodide flow cytometry) and oxidative stress (ROS production, NADPH oxidase activity, and lipid peroxidation). More importantly, reduced AKAP150 expression significantly inhibited high-glucose-induced membrane translocation and activation of cPKC and suppressed the increases in the phosphorylation of p65 NF-κB and p47(phox). Immunofluorescent coexpression and immunoprecipitation indicated enhanced anchoring of AKAP150 with cPKC within the plasma membrane under hyperglycemia, and AKAP150 preferentially colocalized and functionally bound with PKCα and -β isoforms. These results suggest that cardiac AKAP150 positively responds to hyperglycemia and enhances the efficiency of glucotoxicity signaling through a cPKC/p47(phox)/ROS pathway that induces myocardial dysfunction, cardiomyocyte apoptosis, and oxidative stress.
['Zeng|Chao|C|', 'Wang|Jinyi|J|', 'Li|Na|N|', 'Shen|Mingzhi|M|', 'Wang|Dongjuan|D|', 'Yu|Qiujun|Q|', 'Wang|Haichang|H|']
D054758:A Kinase Anchor Proteins D000818:Animals D000831:Animals, Newborn D017209:Apoptosis D002478:Cells, Cultured D003921:Diabetes Mellitus, Experimental D058065:Diabetic Cardiomyopathies D005947:Glucose D057809:HEK293 Cells D006331:Heart Diseases D006801:Humans D006943:Hyperglycemia D008297:Male D032383:Myocytes, Cardiac D018384:Oxidative Stress D011493:Protein Kinase C D051381:Rats D017207:Rats, Sprague-Dawley
AKAP150 glucotoxicity conventional PKC cardiomyocyte oxidative stress