scholarly journals Differential Regulation of Angiotensin II-induced Expression of Connective Tissue Growth Factor by Protein Kinase C Isoforms in the Myocardium

2005 ◽  
Vol 280 (16) ◽  
pp. 15719-15726 ◽  
Author(s):  
Zhiheng He ◽  
Kerrie J. Way ◽  
Emi Arikawa ◽  
Eva Chou ◽  
Darren M. Opland ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Growth Factor ◽  
Protein Kinase ◽  
Connective Tissue ◽  
Mrna Expression ◽  
Tissue Growth ◽  
Dominant Negative ◽  
Wild Type ◽  
Kinase C

Protein kinase C (PKC) and angiotensin II (AngII) can regulate cardiac function in pathological conditions such as in diabetes or ischemic heart disease. We have reported that expression of connective tissue growth factor (CTGF) is increased in the myocardium of diabetic mice. Now we showed that the increase in CTGF expression in cardiac tissues of streptozotocin-induced diabetic rats was reversed by captopril and islet cell transplantation. Infusion of AngII in rats increased CTGF mRNA expression by 15-fold, which was completely inhibited by co-infusion with AT1 receptor antagonist, candesartan. Similarly, incubation of cultured cardiomyocytes with AngII increased CTGF mRNA expression by 2-fold, which was blocked by candesartan and a general PKC inhibitor, GF109203X. The role of PKC isoform-dependent action was further studied using adenoviral vector-mediated gene transfer of dominant negative (dn) PKC or wild type PKC isoforms. Expression of dnPKCα, -ϵ, and -ζ isoforms suppressed AngII-induced CTGF expression in cardiomyocytes. In contrast, expression of dominant negative PKCδ significantly increased AngII-induced CTGF expression, whereas expression of wild type PKCδ inhibited this induction. This inhibitory effect was further confirmed in the myocardium of transgenic mice with cardiomyocyte-specific overexpression of PKCδ (δTg mice). Thus, AngII can regulate CTGF expression in cardiomyocytes through a PKC activation-mediated pathway in an isoform-selective manner both in physiological and diabetic states and may contribute to the development of cardiac fibrosis in diabetic cardiomyopathy.

scholarly journals Serine Phosphorylation Sites on IRS2 Activated by Angiotensin II and Protein Kinase C To Induce Selective Insulin Resistance in Endothelial Cells

2013 ◽  
Vol 33 (16) ◽  
pp. 3227-3241 ◽  
Author(s):  
Kyoungmin Park ◽  
Qian Li ◽  
Christian Rask-Madsen ◽  
Akira Mima ◽  
Koji Mizutani ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Mutational Analysis ◽  
Dominant Negative ◽  
Serine Phosphorylation ◽  
Kinase C ◽  
Pkc Activation

Protein kinase C (PKC) activation, induced by hyperglycemia and angiotensin II (AngII), inhibited insulin-induced phosphorylation of Akt/endothelial nitric oxide (eNOS) by decreasing tyrosine phosphorylation of IRS2 (p-Tyr-IRS2) in endothelial cells. PKC activation by phorbol ester (phorbol myristate acetate [PMA]) reduced insulin-induced p-Tyr-IRS2 by 46% ± 13% and, similarly, phosphorylation of Akt/eNOS. Site-specific mutational analysis showed that PMA increased serine phosphorylation at three sites on IRS2 (positions 303, 343, and 675), which affected insulin-induced tyrosine phosphorylation of IRS2 at positions 653, 671, and 911 (p-Tyr-IRS2) and p-Akt/eNOS. Specific PKCβ2 activation decreased p-Tyr-IRS2 and increased the phosphorylation of two serines (Ser303 and Ser675) on IRS2 that were confirmed in cells overexpressing single point mutants of IRS2 (S303A or S675A) containing a PKCβ2-dominant negative or selective PKCβ inhibitor. AngII induced phosphorylation only on Ser303 of IRS2 and inhibited insulin-induced p-Tyr911 of IRS2 and p-Akt/eNOS, which were blocked by an antagonist of AngII receptor I, losartan, or overexpression of single mutant S303A of IRS2. Increases in p-Ser303 and p-Ser675 and decreases in p-Tyr911 of IRS2 were observed in vessels of insulin-resistant Zucker fatty rats versus lean rats. Thus, AngII or PKCβ activation can phosphorylate Ser303 and Ser675 in IRS2 to inhibit insulin-induced p-Tyr911 and its anti-atherogenic actions (p-Akt/eNOS) in endothelial cells.

Regulation of vascular angiotensin II receptors by EGF

1997 ◽  
Vol 273 (4) ◽  
pp. C1241-C1249 ◽  
Author(s):  
Michael E. Ullian ◽  
John R. Raymond ◽  
Mark C. Willingham ◽  
Richard V. Paul
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Growth Factor ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Receptor Expression ◽  
Ang Ii ◽  
Receptor Density ◽  
Kinase C ◽  
Surface Receptor

After vascular endothelial injury, angiotensin II (ANG II) plays a role in the resulting hypertrophic response, and expression of epidermal growth factor (EGF) is enhanced. Therefore, we tested the possibility that EGF regulates vascular ANG II action and receptor expression. Incubation of cultured aortic vascular smooth muscle cells (VSMC) with EGF (or basic fibroblast growth factor but not platelet-derived growth factor isoforms) resulted in concentration-dependent (1–50 ng/ml EGF), time-dependent (>8 h), and reversible decreases in ANG II surface receptor density. For example, a 50% reduction was observed after exposure to 50 ng/ml EGF for 24 h. Incubation of cultured VSMC with 50 ng/ml EGF for 24 h resulted in a 77% reduction in ANG II-stimulated inositol phosphate formation. EGF not only prevented but also reversed ANG II receptor upregulation by 100 nM corticosterone. The specific tyrosine kinase inhibitor tyrphostin A48 (50 μM) reduced EGF-stimulated thymidine incorporation and EGF-stimulated phosphorylation of mitogen-activated protein kinase but did not prevent EGF from reducing ANG II receptor density. Neither pertussis toxin (100 ng/ml) nor downregulation of protein kinase C by phorbol myristate acetate (100 nM for 24 h) prevented EGF from reducing ANG II receptor density. In summary, EGF is a potent negative regulator of vascular ANG II surface receptor density and ANG II action by mechanisms that do not appear to include tyrosine phorphorylation, pertussis toxin-sensitive G proteins, or phorbol ester-sensitive protein kinase C. The possibility that EGF shifts the cell culture phenotype to one that exhibits reduced surface ANG II density cannot be eliminated by the present studies.

scholarly journals The Small Mr Ras-like GTPase Rap1 and the Phospholipase C Pathway Act to Regulate Phagocytosis inDictyostelium discoideum

1999 ◽  
Vol 10 (2) ◽  
pp. 393-406 ◽  
Author(s):  
David J. Seastone ◽  
Linyi Zhang ◽  
Greg Buczynski ◽  
Patrick Rebstein ◽  
Gerald Weeks ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Protein Tyrosine Kinase ◽  
Dominant Negative ◽  
Wild Type ◽  
Cortical Actin ◽  
Calphostin C ◽  
Kinase C ◽  
Protein Kinase C Inhibitor

The function of the small-Mr Ras-like GTPase Rap1 remains largely unknown, but this protein has been demonstrated to regulate cortical actin-based morphologic changes inDictyostelium and the oxidative burst in mammalian neutrophils. To test whether Rap1 regulates phagocytosis, we biochemically analyzed cell lines that conditionally and modestly overexpressed wild-type [Rap1 WT(+)], constitutively active [Rap1 G12T(+)], and dominant negative [Rap1 S17N(+)] forms of D. discoideum Rap1. The rates of phagocytosis of bacteria and latex beads were significantly higher in Rap1 WT(+) and Rap1 G12T(+) cells and were reduced in Rap1 S17N(+) cells. The addition of inhibitors of protein kinase A, protein kinase G, protein tyrosine kinase, or phosphatidylinositide 3-kinase did not affect phagocytosis rates in wild-type cells. In contrast, the addition of U73122 (a phospholipase C inhibitor), calphostin C (a protein kinase C inhibitor), and BAPTA-AM (an intracellular Ca2+ chelator) reduced phagocytosis rates by 90, 50, and 65%, respectively, suggesting both arms of the phospholipase C signaling pathways played a role in this process. Other protein kinase C–specific inhibitors, such as chelerythrine and bisindolylmaleimide I, did not reduce phagocytosis rates in control cells, suggesting calphostin C was affecting phagocytosis by interfering with a protein containing a diacylglycerol-binding domain. The addition of calphostin C did not reduce phagocytosis rates in Rap1 G12T(+) cells, suggesting that the putative diacylglycerol-binding protein acted upstream in a signaling pathway with Rap1. Surprisingly, macropinocytosis was significantly reduced in Rap1 WT(+) and Rap1 G12T(+) cells compared with control cells. Together our results suggest that Rap1 and Ca2+ may act together to coordinate important early events regulating phagocytosis.

scholarly journals Mapping of Atypical Protein Kinase C within the Nerve Growth Factor Signaling Cascade: Relationship to Differentiation and Survival of PC12 Cells

2000 ◽  
Vol 20 (13) ◽  
pp. 4494-4504 ◽  
Author(s):  
Marie W. Wooten ◽  
M. Lamar Seibenhener ◽  
Kimberly B. W. Neidigh ◽  
Michel L. Vandenplas
Keyword(s):  
Protein Kinase C ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Protein Kinase ◽  
Pc12 Cells ◽  
Dominant Negative ◽  
Atypical Protein Kinase C ◽  
Nerve Growth ◽  
Atypical Protein Kinase ◽  
Kinase C

ABSTRACT The pathway by which atypical protein kinase C (aPKC) contributes to nerve growth factor (NGF) signaling is poorly understood. We previously reported that in PC12 cells NGF-induced activation of mitogen-activated protein kinase (MAPK) occurs independently of classical and nonclassical PKC isoforms, whereas aPKC isoforms were shown to be required for NGF-induced differentiation. NGF-induced activation of PKC-ι was observed to be dependent on phosphatidylinositol 3-kinase (PI3K) and led to coassociation of PKC-ι with Ras and Src. Expression of dominant negative mutants of either Src (DN2) or Ras (Asn-17) impaired activation of PKC-ι by NGF. At the level of Raf-1, neither PKC-ι nor PI3 kinase was required for activation; however, PKC-ι could weakly activate MEK. Inhibitors of PKC-ι activity and PI3K had no effect on NGF-induced MAPK or p38 activation but reduced NGF-stimulated c-Jun N-terminal kinase activity. Src, PI3K, and PKC-ι were likewise required for NGF-induced NF-κB activation and cell survival, whereas Ras was not required for either survival or NF-κB activation but was required for differentiation. IKK existed as a complex with PKC-ι, Src and IκB. Consistent with a role for Src in regulating NF-κB activation, an absence of Src activity impaired recruitment of PKC-ι into an IKK complex and markedly impaired NGF-induced translocation of p65/NF-κB to the nucleus. These findings reveal that in PC12 cells, aPKCs comprise a molecular switch to regulate differentiation and survival responses coupled downstream to NF-κB. On the basis of these findings, Src emerges as a critical upstream regulator of both PKC-ι and the NF-κB pathway.

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