Maturation and the role of PKC-mediated contractility in ovine cerebral arteries.
Ca2+-independent pathways such as protein kinase C (PKC), extracellular-regulated kinases 1 and 2 (ERK1/2), and Rho kinase 1 and 2 (ROCK1/2) play important roles in modulating cerebral vascular tone. Because the roles of these kinases vary with maturational age, we tested the hypothesis that PKC differentially regulates the Ca2+-independent pathways and their effects on cerebral arterial contractility with development. We simultaneously examined the responses of arterial tension and intracellular Ca2+ concentration and used Western immunoblot analysis to measure ERK1/2, RhoA, 20 kDa regulatory myosin light chain (MLC20), PKC-potentiated inhibitory protein of 17 kDa (CPI-17), and caldesmon. Phorbol 12,13-dibutyrate (PDBu)-mediated PKC activation produced a robust contractile response, which was increased a further 20 to 30% by U-0126 (MEK inhibitor) in cerebral arteries of both age groups. Of interest, in the fetal cerebral arteries, PDBu leads to an increased phosphorylation of ERK2 compared with ERK1, whereas in adult arteries, we observed an increased phosphorylation of ERK1 compared with ERK2. Also, in the present study, RhoA/ROCK played a significant role in the PDBu-mediated contractility of fetal cerebral arteries, whereas in adult cerebral arteries, CPI-17 and caldesmon had a significantly greater role compared with the fetus. PDBu also led to an increased MLC20 phosphorylation, a response blunted by the inhibition of myosin light chain kinase only in the fetus. Overall, the present study demonstrates an important maturational shift from RhoA/ROCK-mediated to CPI-17/caldesmon-mediated PKC-induced contractile response in ovine cerebral arteries.
Goyal
Ravi
R
Department of Physiology, Center for Perinatal Biology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA.
Mittal
Ashwani
A
Chu
Nina
N
Shi
Lijun
L
Zhang
Lubo
L
Longo
Lawrence D
LD
D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002536:Cerebral Arteries / Q000187:drug effects / Q000196:embryology / Q000201:enzymology*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D005865:Gestational Age; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012756:Sheep; D015398:Signal Transduction; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D002148:Calmodulin-Binding Proteins; D020536:Enzyme Activators; D018994:Myosin Light Chains; D047428:Protein Kinase Inhibitors; D015240:Phorbol 12,13-Dibutyrate; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010749:Phosphoprotein Phosphatases; D020742:rhoA GTP-Binding Protein; D002118:Calcium