Angiotensin II-induced protein kinase D activation is regulated by protein kinase Cdelta and mediated via the angiotensin II type 1 receptor in vascular smooth muscle cells.
OBJECTIVE
Angiotensin II (Ang II), through its specific signaling cascades, exerts multiple effects on vascular smooth muscle cells (SMCs). It has been shown that Ang II stimulates activation of protein kinase D (PKD), a member of a new class of serine-threonine kinases. However, little is known regarding the upstream cascade of the intracellular signaling that leads to PKD activation. In the present study, we investigated upstream molecules that mediate Ang II-induced PKD activation in SMCs.


RESULTS
Protein kinase C (PKC) inhibitors completely block Ang II-induced PKD activation, and pretreatment with phorbol 12,13-dibutyrate downregulates Ang II-induced PKD activation, indicating that classical or novel isoforms of PKC mediate Ang II-induced PKD activation. Furthermore, the finding that rottlerin, a PKCdelta-specific inhibitor, blocks PKD activation suggests that PKCdelta, a member of novel PKCs, mediates Ang II-induced PKD activation. By using dominant-negative approaches, our results demonstrate that expression of the dominant-negative PKCdelta, but neither the dominant-negative form of PKCepsilon nor PKCzeta, inhibits PKD activation. These results further substantiate the finding that Ang II-induced PKD activation is mediated by PKCdelta. Moreover, using selective Ang II receptor antagonists, our data show that the Ang II type 1 (AT1) receptor but not the AT2 mediates Ang II-stimulated PKD activation.


CONCLUSIONS
This study reveals for the first time that Ang II-induced PKD activation is mediated via AT1 and regulated by PKCdelta in living cells. These data may provide new insights into molecular mechanisms involved in Ang II-induced physiological and pathological events.
Tan
Mingqi
M
Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA.
Xu
Xuemin
X
Ohba
Motoi
M
Cui
Mei-Zhen
MZ
D000098:Acetophenones / Q000494:pharmacology; D000804:Angiotensin II / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000166:cytology; D001578:Benzopyrans / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism; D013997:Time Factors
D000098:Acetophenones; D001578:Benzopyrans; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D015240:Phorbol 12,13-Dibutyrate; C085746:rottlerin; C089212:protein kinase D; D011493:Protein Kinase C