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Par-4: A New Activator of Myosin Phosphatase

Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis re...

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Detalles Bibliográficos
Autores principales: Vetterkind, Susanne, Lee, Eunhee, Sundberg, Eric, Poythress, Ransom H., Tao, Terence C., Preuss, Ute, Morgan, Kathleen G.
Formato: Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2847525/
https://www.ncbi.nlm.nih.gov/pubmed/20130087
http://dx.doi.org/10.1091/mbc.E09-08-0711
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author Vetterkind, Susanne
Lee, Eunhee
Sundberg, Eric
Poythress, Ransom H.
Tao, Terence C.
Preuss, Ute
Morgan, Kathleen G.
author_facet Vetterkind, Susanne
Lee, Eunhee
Sundberg, Eric
Poythress, Ransom H.
Tao, Terence C.
Preuss, Ute
Morgan, Kathleen G.
author_sort Vetterkind, Susanne
collection PubMed
description Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response (Par)-4 modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4 and reduced by Par-4 phosphorylation. Overexpression of Par-4 leads to increased phosphatase activity of immunoprecipitated MP, whereas small interfering RNA knockdown of endogenous Par-4 significantly decreases MP activity and increases MYPT1 phosphorylation. LC20 phosphorylation assays demonstrate that overexpression of Par-4 reduces LC20 phosphorylation. In contrast, a phosphorylation site mutant, but not wild-type Par-4, interferes with zipper-interacting protein kinase (ZIPK)-mediated MP inhibition. We conclude from our results Par-4 operates through a “padlock” model in which binding of Par-4 to MYPT1 activates MP by blocking access to the inhibitory phosphorylation sites, and inhibitory phosphorylation of MYPT1 by ZIPK requires “unlocking” of Par-4 by phosphorylation and displacement of Par-4 from the MP complex.
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spelling pubmed-28475252010-06-16 Par-4: A New Activator of Myosin Phosphatase Vetterkind, Susanne Lee, Eunhee Sundberg, Eric Poythress, Ransom H. Tao, Terence C. Preuss, Ute Morgan, Kathleen G. Mol Biol Cell Articles Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response (Par)-4 modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4 and reduced by Par-4 phosphorylation. Overexpression of Par-4 leads to increased phosphatase activity of immunoprecipitated MP, whereas small interfering RNA knockdown of endogenous Par-4 significantly decreases MP activity and increases MYPT1 phosphorylation. LC20 phosphorylation assays demonstrate that overexpression of Par-4 reduces LC20 phosphorylation. In contrast, a phosphorylation site mutant, but not wild-type Par-4, interferes with zipper-interacting protein kinase (ZIPK)-mediated MP inhibition. We conclude from our results Par-4 operates through a “padlock” model in which binding of Par-4 to MYPT1 activates MP by blocking access to the inhibitory phosphorylation sites, and inhibitory phosphorylation of MYPT1 by ZIPK requires “unlocking” of Par-4 by phosphorylation and displacement of Par-4 from the MP complex. The American Society for Cell Biology 2010-04-01 /pmc/articles/PMC2847525/ /pubmed/20130087 http://dx.doi.org/10.1091/mbc.E09-08-0711 Text en © 2010 by The American Society for Cell Biology
spellingShingle Articles
Vetterkind, Susanne
Lee, Eunhee
Sundberg, Eric
Poythress, Ransom H.
Tao, Terence C.
Preuss, Ute
Morgan, Kathleen G.
Par-4: A New Activator of Myosin Phosphatase
title Par-4: A New Activator of Myosin Phosphatase
title_full Par-4: A New Activator of Myosin Phosphatase
title_fullStr Par-4: A New Activator of Myosin Phosphatase
title_full_unstemmed Par-4: A New Activator of Myosin Phosphatase
title_short Par-4: A New Activator of Myosin Phosphatase
title_sort par-4: a new activator of myosin phosphatase
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2847525/
https://www.ncbi.nlm.nih.gov/pubmed/20130087
http://dx.doi.org/10.1091/mbc.E09-08-0711
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