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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...
Autores principales: | , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
The American Society for Cell Biology
2010
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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. |
format | Text |
id | pubmed-2847525 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2010 |
publisher | The American Society for Cell Biology |
record_format | MEDLINE/PubMed |
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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