title: AKAP12 in astrocytes induces barrier functions in human endothelial cells through protein kinase Czeta.
abstract: Interactions between astrocytes and blood vessels are essential for the formation and maintenance of the blood-neural barrier (BNB). Astrocyte-derived A-kinase anchor protein 12 (AKAP12) influences BNB formation, but the mechanism of regulation of BNB functions by AKAP12 is not fully understood. We have defined a new pathway of barriergenesis in human retina microvascular endothelial cells (HRMECs) involving astrocytic AKAP12. Treatment of HRMECs with conditioned media from AKAP12-overexpressing astrocytes reduced phosphorylation of protein kinase Czeta (PKCzeta), decreased the levels of vascular endothelial growth factor (VEGF) mRNA and protein, and increased thrombospondin-1 (TSP-1) levels, which led to antiangiogenesis and barriergenesis. Transfection of a small interference RNA targeting PKCzeta decreased VEGF levels and increased TSP-1 levels in HRMECs. Rho is a putative downstream signal of PKCzeta, and inhibition of Rho kinase with a specific inhibitor, Y27632, decreased VEGF levels and increased TSP-1 levels. We therefore suggest that AKAP12 in astrocytes differentially regulates the expression of VEGF and TSP-1 via the inhibition of PKCzeta phosphorylation and Rho kinase activity in HRMECs.
authors.affiliation: NeuroVascular Coordination Research Center, College of Pharmacy and Research, Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea.
authors.forename: Yoon Kyung
authors.initials: YK
authors.lastname: Choi
authors.forename: Kyu-Won
authors.initials: KW
authors.lastname: Kim
mesh_terms: D054758:A Kinase Anchor Proteins / Q000502:physiology*; D000577:Amides / Q000494:pharmacology; D001253:Astrocytes / Q000737:chemistry / Q000378:metabolism*; D001813:Blood-Retinal Barrier / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D019700:Thrombospondin 1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D054758:A Kinase Anchor Proteins; D000577:Amides; D018797:Cell Cycle Proteins; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D011493:Protein Kinase C; D011506:Proteins; D011725:Pyridines; D012333:RNA, Messenger; D019700:Thrombospondin 1; D042461:Vascular Endothelial Growth Factor A; D000099221:Protein Kinase C zeta; C491162:AKAP12 protein, human; C108830:Y 27632