AKAP150 mobilizes cPKC-dependent cardiac glucotoxicity.

Abstract

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.

• Authors: Chao Zeng, Jinyi Wang, Na Li, Mingzhi Shen, Dongjuan Wang, Qiujun Yu, Haichang Wang
• Journal: American journal of physiology. Endocrinology and metabolism (Am J Physiol Endocrinol Metab) Vol. 307 Issue 4 Pg. E384-97 (Aug 15 2014) ISSN: 1522-1555 [Electronic] United States
• PMID: 25005497 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 the American Physiological Society.

Chemical References

• A Kinase Anchor Proteins
• Akap5 protein, rat
• Protein Kinase C
• Glucose

Topics

• A Kinase Anchor Proteins (physiology)
• Animals
• Animals, Newborn
• Apoptosis (drug effects)
• Cells, Cultured
• Diabetes Mellitus, Experimental (complications, metabolism)
• Diabetic Cardiomyopathies (metabolism, pathology)
• Glucose (toxicity)
• HEK293 Cells
• Heart Diseases (etiology, metabolism)
• Humans
• Hyperglycemia (complications, metabolism)
• Male
• Myocytes, Cardiac (drug effects, physiology)
• Oxidative Stress (drug effects)
• Protein Kinase C (metabolism)
• Rats
• Rats, Sprague-Dawley