Expression of Y53A-Actin in Dictyostelium Disrupts the Cytoskeleton and Inhibits Intracellular and Intercellular Chemotactic Signaling |
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Authors: | Shi Shu Xiong Liu Paul W Kriebel Myoung-Soon Hong Mathew P Daniels Carole A Parent Edward D Korn |
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Institution: | From the ‡Laboratory of Cell Biology, NHLBI.;the §Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, and ;the ¶Electron Microscopy Core Facility, NHLBI, National Institutes of Health, Bethesda, Maryland 20892 |
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Abstract: | We showed previously that phosphorylation of Tyr53, or its mutation to Ala, inhibits actin polymerization in vitro with formation of aggregates of short filaments, and that expression of Y53A-actin in Dictyostelium blocks differentiation and development at the mound stage (Liu, X., Shu, S., Hong, M. S., Levine, R. L., and Korn, E. D. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 13694–13699; Liu, X., Shu, S., Hong, M. S., Yu, B., and Korn, E. D. (2010) J. Biol. Chem. 285, 9729–9739). We now show that expression of Y53A-actin, which does not affect cell growth, phagocytosis, or pinocytosis, inhibits the formation of head-to-tail cell streams during cAMP-induced aggregation, although individual amoebae chemotax normally. We show that expression of Y53A-actin causes a 50% reduction of cell surface cAMP receptors, and inhibits cAMP-induced increases in adenylyl cyclase A activity, phosphorylation of ERK2, and actin polymerization. Trafficking of vesicles containing adenylyl cyclase A to the rear of the cell and secretion of the ACA vesicles are also inhibited. The actin cytoskeleton of cells expressing Y53A-actin is characterized by numerous short filaments, and bundled and aggregated filaments similar to the structures formed by copolymerization of purified Y53A-actin and wild-type actin in vitro. This disorganized actin cytoskeleton may be responsible for the inhibition of intracellular and intercellular cAMP signaling in cells expressing F-Y53A-actin. |
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Keywords: | Actin Chemotaxis Development Dictyostelium Differentiation Signal Transduction cAMP Signaling |
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