Enhancement of myosin II/actin turnover at the contractile ring induces slower furrowing in dividing HeLa cells

2011 ◽  
Vol 435 (3) ◽  
pp. 569-576 ◽  
Author(s):  
Tomo Kondo ◽  
Kozue Hamao ◽  
Keiju Kamijo ◽  
Hiroshi Kimura ◽  
Makiko Morita ◽  
...  
Keyword(s):  
Hela Cells ◽  
Fluorescence Recovery After Photobleaching ◽  
Kinase Inhibitor ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Filamentous Actin ◽  
Contractile Ring ◽  
Rho Kinase Inhibitor ◽  
Actin Turnover ◽  
Dividing Cells

Myosin II ATPase activity is enhanced by the phosphorylation of MRLC (myosin II regulatory light chain) in non-muscle cells. It is well known that pMRLC (phosphorylated MRLC) co-localizes with F-actin (filamentous actin) in the CR (contractile ring) of dividing cells. Recently, we reported that HeLa cells expressing non-phosphorylatable MRLC show a delay in the speed of furrow ingression, suggesting that pMRLC plays an important role in the control of furrow ingression. However, it is still unclear how pMRLC regulates myosin II and F-actin at the CR to control furrow ingression during cytokinesis. In the present study, to clarify the roles of pMRLC, we measured the turnover of myosin II and actin at the CR in dividing HeLa cells expressing fluorescent-tagged MRLCs and actin by FRAP (fluorescence recovery after photobleaching). A myosin II inhibitor, blebbistatin, caused an enhancement of the turnover of MRLC and actin at the CR, which induced a delay in furrow ingression. Furthermore, only non-phosphorylatable MRLC and a Rho-kinase inhibitor, Y-27632, accelerated the turnover of MRLC and actin at the CR. Interestingly, the effect of Y-27632 was cancelled in the cell expressing phosphomimic MRLCs. Taken together, these results reveal that pMRLC reduces the turnover of myosin II and also actin at the CR. In conclusion, we show that the enhancement of myosin II and actin turnover at the CR induced slower furrowing in dividing HeLa cells.

scholarly journals Inhibition and Redistribution of NHE3, the Apical Na+/H+ Exchanger, by Clostridium difficile Toxin B

2004 ◽  
Vol 123 (5) ◽  
pp. 491-504 ◽  
Author(s):  
Hisayoshi Hayashi ◽  
Katalin Szászi ◽  
Natasha Coady-Osberg ◽  
Wendy Furuya ◽  
Anthony P. Bretscher ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Apical Surface ◽  
Filamentous Actin ◽  
Toxin B ◽  
Rho Kinase Inhibitor ◽  
Rho Family Gtpases ◽  
Clostridium Difficile Toxin ◽  
Clostridium Difficile Toxin B

NHE3, the apical isoform of the Na+/H+ exchanger, is central to the absorption of salt and water across the intestinal epithelium. We report that treatment of epithelial cells with toxin B of Clostridium difficile, a diarrheal pathogen, causes a pronounced inhibition of NHE3 activity, with little effect on the basolateral NHE1 isoform. Depression of NHE3 activity is accompanied by the translocation of apical exchangers to a subapical endomembrane compartment. Treatment of cells with toxin B increased the fraction of exchangers that were solubilized by nonionic detergents and induced dephosphorylation and extensive redistribution of ezrin. The Rho-kinase inhibitor, Y-27632, also altered the distribution and activity of NHE3. We suggest that inactivation of Rho-family GTPases by clostridial toxin B alters the interaction between NHE3 and the microvillar cytoskeleton, possibly by impairing the ability of ezrin to bridge the exchangers to filamentous actin. Detachment of NHE3 from the actin skeleton would facilitate its internalization, resulting in net disappearance from the apical surface. The consequent inhibition of transport is likely to contribute to the diarrheal effects of C. difficile.

scholarly journals Rho-kinase inhibitor hydroxyfasudil protects against HIV-1 Tat-induced dysfunction of tight junction and neprilysin/Aβ transfer receptor expression in mouse brain microvessels

2021 ◽  
Vol 476 (5) ◽  
pp. 2159-2170
Author(s):  
Qiangtang Chen ◽  
Yu Wu ◽  
Yachun Yu ◽  
Junxiang Wei ◽  
Wen Huang
Keyword(s):  
Tight Junction ◽  
Signaling Pathway ◽  
Mouse Brain ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Receptor Expression ◽  
Mrna Levels ◽  
Brain Microvessels ◽  
Rho Kinase Inhibitor ◽  
Hiv 1

AbstractHIV-1 transactivator protein (Tat) induces tight junction (TJ) dysfunction and amyloid-beta (Aβ) clearance dysfunction, contributing to the development and progression of HIV-1-associated neurocognitive disorder (HAND). The Rho/ROCK signaling pathway has protective effects on neurodegenerative disease. However, the underlying mechanisms of whether Rho/ROCK protects against HIV-1 Tat-caused dysfunction of TJ and neprilysin (NEP)/Aβ transfer receptor expression have not been elucidated. C57BL/6 mice were administered sterile saline (i.p., 100 μL) or Rho-kinase inhibitor hydroxyfasudil (HF) (i.p., 10 mg/kg) or HIV-1 Tat (i.v., 100 μg/kg) or HF 30 min before being exposed to HIV-1 Tat once a day for seven consecutive days. Evans Blue (EB) leakage was detected via spectrophotometer and brain slides in mouse brains. The protein and mRNA levels of zonula occludens-1 (ZO-1), occludin, NEP, receptor for advanced glycation end products (RAGE), and low-density lipoprotein receptor-related protein 1 (LRP1) in mouse brain microvessels were, respectively, analyzed by Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) analyses. Exposure of the mice to HIV-1 Tat increased the amount of EB leakage, EB fluorescence intensity, blood–brain barrier (BBB) permeability, as well as the RAGE protein and mRNA levels, and decreased the protein and mRNA levels of ZO-1, occludin, NEP, and LRP1 in mouse brain microvessels. However, these effects were weakened by Rho-kinase inhibitor HF. Taken together, these results provide information that the Rho/ROCK signaling pathway is involved in HIV-1 Tat-induced dysfunction of TJ and NEP/Aβ transfer receptor expression in the C57BL/6 mouse brain. These findings shed some light on potentiality of inhibiting Rho/Rock signaling pathway in handling HAND.

Rho kinase inhibitor for primary open-angle glaucoma and ocular hypertension

2020 ◽  
Author(s):  
Josefine Clement Freiberg ◽  
Alexander von Spreckelsen ◽  
Naira Khachatryan ◽  
Miriam Kolko ◽  
Augusto Azuara-Blanco ◽  
...  
Keyword(s):  
Ocular Hypertension ◽  
Primary Open Angle Glaucoma ◽  
Kinase Inhibitor ◽  
Open Angle Glaucoma ◽  
Rho Kinase ◽  
Open Angle ◽  
Rho Kinase Inhibitor

scholarly journals A Novel Regulatory Mechanism of Myosin Light Chain Phosphorylation via Binding of 14-3-3 to Myosin Phosphatase

2008 ◽  
Vol 19 (3) ◽  
pp. 1062-1071 ◽  
Author(s):  
Yasuhiko Koga ◽  
Mitsuo Ikebe
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Regulatory Mechanism ◽  
Kinase Inhibitor ◽  
Myosin Ii ◽  
Critical Role ◽  
Rho Kinase ◽  
Myosin Phosphatase ◽  
Dependent Cell ◽  
Direct Binding

Myosin II phosphorylation–dependent cell motile events are regulated by myosin light-chain (MLC) kinase and MLC phosphatase (MLCP). Recent studies have revealed myosin phosphatase targeting subunit (MYPT1), a myosin-binding subunit of MLCP, plays a critical role in MLCP regulation. Here we report the new regulatory mechanism of MLCP via the interaction between 14-3-3 and MYPT1. The binding of 14-3-3β to MYPT1 diminished the direct binding between MYPT1 and myosin II, and 14-3-3β overexpression abolished MYPT1 localization at stress fiber. Furthermore, 14-3-3β inhibited MLCP holoenzyme activity via the interaction with MYPT1. Consistently, 14-3-3β overexpression increased myosin II phosphorylation in cells. We found that MYPT1 phosphorylation at Ser472 was critical for the binding to 14-3-3. Epidermal growth factor (EGF) stimulation increased both Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase inhibitor inhibited the EGF-induced Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase specific siRNA also decreased EGF-induced Ser472 phosphorylation correlated with the decrease in MLC phosphorylation. The present study revealed a new RhoA/Rho-kinase–dependent regulatory mechanism of myosin II phosphorylation by 14-3-3 that dissociates MLCP from myosin II and attenuates MLCP activity.

Protective effect of hydroxyfasudil, a Rho kinase inhibitor, on ventral prostatic hyperplasia in the spontaneously hypertensive rat

The Prostate ◽  
2015 ◽  
Vol 75 (15) ◽  
pp. 1774-1782 ◽  
Author(s):  
Felix Holmström ◽  
Shogo Shimizu ◽  
Takahiro Shimizu ◽  
Youichirou Higashi ◽  
Darryl T. Martin ◽  
...  
Keyword(s):  
Protective Effect ◽  
Kinase Inhibitor ◽  
Spontaneously Hypertensive Rat ◽  
Rho Kinase ◽  
Prostatic Hyperplasia ◽  
Spontaneously Hypertensive ◽  
Hypertensive Rat ◽  
Rho Kinase Inhibitor
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