Abstract
We found that overexpression of RhoGDIbeta, a Rho GDP dissociation inhibitor, induced hypertrophic growth and suppressed cell cycle progression in a cultured cardiomyoblast cell line. Knockdown of RhoGDIbeta expression by RNA interference blocked hypertrophic growth. We further demonstrated that RhoGDIbeta physically interacts with ZAK and is phosphorylated by ZAK in vitro, and this phosphorylation negatively regulates RhoGDIbeta functions. Moreover, the ZAK-RhoGDIbeta interaction may maintain ZAK in an inactive hypophosphorylated form. These two proteins could negatively regulate one another such that ZAK suppresses RhoGDIbeta functions through phosphorylation and RhoGDIbeta counteracts the effects of ZAK by physical interaction. Knockdown of ZAK expression in ZAK- and RhoGDIbeta-expressing cells by ZAK-specific RNA interference restored the full functions of RhoGDIbeta.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Cell Cycle / physiology
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Cell Line
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Cell Movement / physiology
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Guanine Nucleotide Dissociation Inhibitors / genetics
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Guanine Nucleotide Dissociation Inhibitors / metabolism*
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Humans
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Hypertrophy / metabolism*
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Hypertrophy / pathology
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Leucine Zippers
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Protein Isoforms / genetics
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Protein Isoforms / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Rats
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Signal Transduction / physiology
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
Substances
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Guanine Nucleotide Dissociation Inhibitors
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Protein Isoforms
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RNA, Small Interfering
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Recombinant Fusion Proteins
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
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Protein Serine-Threonine Kinases