RhoA- and PKC-α-mediated phosphorylation of MYPT and its association with HSP27 in colonic smooth muscle cells.

2006 ◽  
Vol 290 (1) ◽  
pp. G83-G95 ◽  
Author(s):  
Suresh B. Patil ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Phosphatase Activity ◽  
Cross Talk ◽  
Rho Kinase ◽  
Muscle Cells ◽  
Selective Inhibition ◽  
Particulate Fraction ◽  
Myosin Phosphatase ◽  
Sustained Phosphorylation

Agonist-induced activation of the RhoA/Rho kinase (ROCK) pathway results in inhibition of myosin phosphatase and maintenance of myosin light chain (MLC20) phosphorylation. We have shown that RhoA/ROCKII translocates and associates with heat shock protein (HSP)27 in the particulate fraction. We hypothesize that inhibition of the 130-kDa regulatory myosin-binding subunit (MYPT) requires its association with HSP27 in the particulate fraction. Furthermore, it is not certain whether regulation of MYPT by CPI-17 or by ROCKII is due to cross talk between RhoA and PKC-α. Presently, we examined the cross talk between RhoA and PKC-α in the regulation of MYPT phosphorylation in rabbit colon smooth muscle cells. Acetylcholine induced 1) sustained phosphorylation of PKC-α, CPI-17, and MYPT; 2) an increase in the association of phospho-MYPT with HSP27 in the particulate fraction; 3) a decrease in myosin phosphatase activity (66.21 ± 3.52 and 42.19 ± 3.85%nM/ml lysate at 30 s and 4 min); and 4) an increase in PKC activity (298.12 ± 46.60% and 290.59 ± 22.07% at 30 s and 4 min). Inhibition of RhoA/ROCKII by Y-27632 inhibited phosphorylation of MYPT and its association with HSP27. Both Y27632 and a negative dominant construct of RhoA inhibited phosphorylation of MYPT and CPI-17. Inhibition of PKCs or calphostin C or selective inhibition of PKC-α by negative dominant constructs inhibited phosphorylation of MYPT and CPI-17. The results suggest that 1) acetylcholine induces activation of both RhoA and/or PKC-α pathways, suggesting cross talk between RhoA and PKC-α resulting in phosphorylation of MYPT, inhibition of myosin phosphatase activity, and maintenance of MLC phosphorylation; and 2) phosphorylated MYPT is associated with HSP27 and translocated to the particulate fraction, suggesting a scaffolding role for HSP27 in mediating the association of the complex MYPT/RhoA-ROCKII. Thus both pathways (PKC and RhoA) converge on the regulation of myosin phosphatase activities and modulate sustained phosphorylation of MLC20.

scholarly journals Rho kinase inhibitor HA-1077 prevents Rho-mediated myosin phosphatase inhibition in smooth muscle cells

2000 ◽  
Vol 278 (1) ◽  
pp. C57-C65 ◽  
Author(s):  
Hiromitsu Nagumo ◽  
Yasuharu Sasaki ◽  
Yoshitaka Ono ◽  
Hiroyuki Okamoto ◽  
Minoru Seto ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Phosphatase Activity ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Myosin Phosphatase ◽  
Rho Kinase Inhibitor

In smooth muscle, a Rho-regulated system of myosin phosphatase exists; however, it has yet to be established whether Rho kinase, one of the downstream effectors of Rho, mediates the regulation of myosin phosphatase activity in vivo. In the present study, we demonstrate in permeabilized vascular smooth muscle cells (SMCs) that the vasodilator 1-(5-isoquinolinesulfonyl)-homopiperazine (HA-1077), which we show to be a potent inhibitor of Rho kinase, dose dependently inhibits Rho-mediated enhancement of Ca2+-induced 20-kDa myosin light chain (MLC20) phosphorylation due to abrogating Rho-mediated inhibition of MLC20dephosphorylation. By an immune complex phosphatase assay, we found that guanosine 5′- O-(3-thiotriphosphate) (GTPγS) stimulation of permeabilized SMCs caused a decrease in myosin phosphatase activity with an increase in the extent of phosphorylation of the 130-kDa myosin-binding regulatory subunit (MBS) of myosin phosphatase in a Rho-dependent manner. HA-1077 abolished both of the Rho-mediated events. Moreover, we observed that the pleckstrin homology/cystein-rich domain protein of Rho kinase, a dominant negative inhibitor of Rho kinase, inhibited GTPγS-induced phosphorylation of MBS. These results provide direct in vivo evidence that Rho kinase mediates inhibition of myosin phosphatase activity with resultant enhancement of MLC20phosphorylation in smooth muscle and reveal the usefulness of HA-1077 as a Rho kinase inhibitor.

RhoA-Rho kinase pathway mediates thrombin- and U-46619-induced phosphorylation of a myosin phosphatase inhibitor, CPI-17, in vascular smooth muscle cells

2005 ◽  
Vol 289 (2) ◽  
pp. C352-C360 ◽  
Author(s):  
Huan Pang ◽  
Zhenheng Guo ◽  
Wen Su ◽  
Zhongwen Xie ◽  
Masumi Eto ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Rho Kinase ◽  
Muscle Cells ◽  
Myosin Phosphatase ◽  
Kinase C

Protein kinase C-potentiated phosphatase inhibitor of 17 kDa (CPI-17) mediates some agonist-induced smooth muscle contraction by suppressing the myosin phosphatase in a phosphorylation-dependent manner. The physiologically relevant kinases that phosphorylate CPI-17 remain to be identified. Several previous studies have shown that some agonist-induced CPI-17 phosphorylation in smooth muscle tissues was attenuated by the Rho kinase (ROCK) inhibitor Y-27632, suggesting that ROCK is involved in agonist-induced CPI-17 phosphorylation. However, Y-27632 has recently been found to inhibit protein kinase C (PKC)-δ, a well-recognized CPI-17 kinase. Thus the role of ROCK in agonist-induced CPI-17 phosphorylation remains uncertain. The present study was designed to address this important issue. We selectively activated the RhoA pathway using inducible adenovirus-mediated expression of a constitutively active mutant RhoA (V14RhoA) in primary cultured rabbit aortic vascular smooth muscle cells (VSMCs). V14RhoA caused expression level-dependent CPI-17 phosphorylation at Thr38 as well as myosin phosphatase phosphorylation at Thr853. Importantly, we have shown that V14RhoA-induced CPI-17 phosphorylation was not affected by the PKC inhibitor GF109203X but was abolished by Y-27632, suggesting that ROCK but not PKC was involved. Furthermore, we have shown that the contractile agonists thrombin and U-46619 induced CPI-17 phosphorylation in VSMCs. Similarly to V14RhoA-induced CPI-17 phosphorylation, thrombin-induced CPI-17 phosphorylation was not affected by inhibition of PKC with GF109203X, but it was blocked by inhibition of RhoA with adenovirus-mediated expression of exoenzyme C3 as well as by Y-27632. Taken together, our present data provide the first clear evidence indicating that ROCK is responsible for thrombin- and U-46619-induced CPI-17 phosphorylation in primary cultured VSMCs.

scholarly journals Cross-talk between angiotensin II and IGF-1-induced connexin 43 expression in human saphenous vein smooth muscle cells

2011 ◽  
Vol 15 (8) ◽  
pp. 1695-1702 ◽  
Author(s):  
Guanghong Jia ◽  
Anshu Aggarwal ◽  
Amanuel Yohannes ◽  
Deepak M. Gangahar ◽  
Devendra K. Agrawal
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Cross Talk ◽  
Saphenous Vein ◽  
Connexin 43 ◽  
Muscle Cells ◽  
Human Saphenous Vein

Abstract 169: Smad3 Drives Cross-Talk Between TGFß and Wnt/ß-Catenin Signaling Pathways in Smooth Muscle Cells

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Daniel M DiRenzo ◽  
Xu Dong Shi ◽  
Lian-Wang Guo ◽  
K Craig Kent
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Wnt Signaling ◽  
Vascular Injury ◽  
Cross Talk ◽  
Intimal Hyperplasia ◽  
Muscle Cells ◽  
Arterial Injury ◽  
Protein Levels ◽  
Qrt Pcr

Restenosis (neo-intimal hyperplasia) occurs in approximately 25-50% of patients undergoing arterial interventions, primarily due to the proliferation and migration of arterial smooth muscle cells (SMCs) into the peri-luminal area. Recently, Wnt/β-catenin signaling has been shown to promote SMC proliferation and enhance neo-intimal hyperplasia but its mechanism of activation is unclear. Interestingly, Wnt/β-catenin has been shown to be activated by TGFβ in mesenchymal stem cells and fibroblasts. We have shown that TGFβ and its downstream signaling protein, Smad3, are upregulated following vascular injury and that Smad3 overexpressing SMCs display enhanced proliferation, migration, and neo-intimal hyperplasia. These results led us to hypothesize that TGFβ, through Smad3, activates Wnt/β-catenin to regulate SMC behavior following arterial injury . In primary rat SMCs, TGFβ (5ng/mL) led to β-catenin activation and relocalization from the plasma membrane to the cytoplasm / nucleus within 24 hours. Furthermore, qRT-PCR results demonstrated that expression of Wnt11 (22 fold) and Wnt9a (3.9 fold) were significantly upregulated after 24 hours of TGFβ stimulation (p<0.05, n=3). In addition, 24 hours of TGFβ stimulation in SMCs overexpressing Smad3 (TGFβ/Smad3) further enhanced the gene expression of Wnt11 (>300 fold) and Wnt9a (14 fold) and also stimulated significant increases in Wnt2b (41 fold), Wnt5a (2.9 fold), and Wnt4 (3.2 fold) (p<0.05, n=3) as measured by qRT-PCR. Western blot results demonstrated that the combined TGFβ/Smad3 stimulation increased β-catenin protein levels, suggesting that TGFβ activates canonical Wnt signaling leading to stabilization of β-catenin protein. In normal rat carotid arteries, β-catenin protein was undetectable via immunohistochemistry but could be seen in SMCs of the vessel media at 3 days post-balloon angioplasty and in neo-intimal cells at 7 and 14 days. Smad3 was also expressed in neo-intimal cells at 7 and 14 days post-angioplasty suggesting that TGFβ, through Smad3, is responsible for Wnt/β-Catenin activation during vascular injury. In conclusion, this work describes a novel cross-talk in SMCs between TGFβ and Wnt signaling which may provide a viable target for future anti-restenotic treatments.

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