AKAP12 in astrocytes induces barrier functions in human endothelial cells through protein kinase Czeta.
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.
Choi
Yoon Kyung
YK
NeuroVascular Coordination Research Center, College of Pharmacy and Research, Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea.
Kim
Kyu-Won
KW
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
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