title: Unique spatiotemporal activation pattern of Cdc42 by Gef1 and Scd1 promotes different events during cytokinesis.
abstract: The Rho-family GTPase Cdc42 regulates cell polarity and localizes to the cell division site. Cdc42 is activated by guanine nucleotide exchange factors (GEFs). We report that Cdc42 promotes cytokinesis via a unique spatiotemporal activation pattern due to the distinct action of its GEFs, Gef1 and Scd1, in fission yeast. Before cytokinetic ring constriction, Cdc42 activation, is Gef1 dependent, and after ring constriction, it is Scd1 dependent. Gef1 localizes to the actomyosin ring immediately after ring assembly and promotes timely onset of ring constriction. Gef1 is required for proper actin organization during cytokinesis, distribution of type V myosin Myo52 to the division site, and timely recruitment of septum protein Bgs1. In contrast, Scd1 localizes to the broader region of ingressing membrane during cytokinetic furrowing. Scd1 promotes normal septum formation, andscd1Δcells display aberrant septa with reduced Bgs1 localization. Thus we define unique roles of the GEFs Gef1 and Scd1 in the regulation of distinct events during cytokinesis. Gef1 localizes first to the cytokinetic ring and promotes timely constriction, whereas Scd1 localizes later to the ingressing membrane and promotes septum formation. Our findings are consistent with reports that complexity in GTPase signaling patterns enables exquisite precision over the control of cellular processes.
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Hercyk
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Mattson
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mohammadi
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Julie
authors.initials: J
authors.lastname: Rich
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Erica
authors.initials: E
authors.lastname: DeBruyne
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996.
authors.forename: Mikayla M
authors.initials: MM
authors.lastname: Clark
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996 mdas@utk.edu.
authors.forename: Maitreyi
authors.initials: M
authors.lastname: Das
mesh_terms: D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; C000613449:Gef1 protein, S pombe; D020662:Guanine Nucleotide Exchange Factors; D064067:Rho Guanine Nucleotide Exchange Factors; D029702:Schizosaccharomyces pombe Proteins; C089769:scd1 protein, S pombe; D000205:Actomyosin; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase; C554097:Myo52 protein, S pombe; D009218:Myosins; D020764:cdc42 GTP-Binding Protein