PubMed Journals: J Biol Chem

  Source:		PMID: 16027158

    		J Biol Chem. 2005 Sep 9;280(36):31913-23.
     		Epub 2005 Jul 18.

			Phosphorylation of coronin 1B by protein
			kinase C regulates interaction with Arp2/3
			and cell motility.

			Cai L(1), Holoweckyj N, Schaller MD, Bear

			Author Information
			(1) Lineberger Comprehensive Cancer Center
			and Department of Cell & Developmental Biology,
			University of North Carolina Chapel Hill
			School of Medicine, Chapel Hill, North Carolina
			27599, USA.

			Coronins are a conserved family of WD
			repeat-containing, actin-binding proteins
			that regulate cell motility in a variety
			of model organisms. Our results show that
			Coronin 1B is a ubiquitously expressed
			member of the mammalian Coronin gene family
			that co-localizes with the Arp2/3 complex
			at the leading edge of fibroblasts, and
			co-immunoprecipitates with this complex.
			Pharmacological experiments show that the
			interaction between Coronin 1B and the Arp2/3
			complex is regulated by protein kinase C
			(PKC) phosphorylation. Coronin 1B is phosphorylated
			by PKC both in vitro and in vivo. Using
			tryptic peptide mapping and mutagenesis,
			we have identified serine 2 (Ser-2) on Coronin
			1B as the major residue phosphorylated by
			PKC in vivo. Rat2 fibroblasts expressing
			the Coronin 1B S2A mutant show enhanced
			ruffling in response to phorbol 12-myristate
			13-acetate (PMA) and increased speed in
			single cell tracking assays. Cells expressing
			the Coronin 1B S2D mutant have attenuated
			PMA-induced ruffling and slower cell speed.
			Expression of the S2A mutant partially protects
			cells from the inhibitory effects of PMA
			on cell speed, whereas expression of the
			S2D mutant renders cells hypersensitive
			to its effects. These data demonstrate that
			Coronin 1B regulates leading edge dynamics
			and cell motility in fibroblasts, and that
			its ability to control motility and interactions
			with the Arp2/3 complex are regulated by
			PKC phosphorylation at Ser-2. Furthermore,
			Coronin 1B phosphorylation is responsible
			for a significant fraction of the effects
			of PMA on fibroblast motility.

			DOI: 10.1074/jbc.M504146200 PMID: 16027158
			[Indexed for MEDLINE]

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