Memoria CD.indd - ISHAM

CDC42p controls yeast-cell shape and virulencein Paracoccidioides brasiliensisAgostinho J. Almeida 1 , Celia Cunha 1 †, Belem Sampaio-Marques 1 †, Jenny A.Carmona 1 , Agostinho Carvalho 1 , Iran Malavazi 2 , H.Y. Steensma 3 ,D.I. Johnson 4 , E. Logarinho 1 , Cecilia Leão 1 , Gustavo H. Goldman 2 ,A.G. Castro 1 , Paula Ludovico 1 , Fernando Rodrigues 11. Life and Health Sciences Research Institute (ICVS),School of Health Sciences, University of Minho, Braga, Portugal.2. Faculdade de Ciências Farmacêuticas de Ribeirão Preto,Universidade de São Paulo, Brazil.3. Institute of Biology, Leiden University, Leiden, The Netherlands.4. Department of Microbiology and Molecular Genetics,University of Vermont, Burlington, Vermont, USA.† These authors contributed equally for this work.e-mail: ajalmeida@ecsaude.uminho.ptPrevious work in our laboratory The multiple budding nature of Paracoccidioides brasiliensisyeast cells has been suggested to follow alternative control mechanisms during cell growth.As the Rho-like GTPase Cdc42p is a pivotal molecule to establish and maintain polarized cellgrowth, we evaluated the role of this protein in the polymorphic morphology and the virulenceof the yeast-form of this pathogenic fungus.The isolated PbCDC42 gene functionally complements ∆cdc42 S. cerevisiae and triggers aloss of spatiotemporal control of cell division in a temperature-dependent manner.By using antisense technology we knocked-down PbCDC42 in P. brasiliensis yeast cellsshowing that, despite it does not eliminate the multiple budding phenotype, it promotes amore organized and controlled cell growth by decreasing cell size and the typical polymorphismof wild-type cells.Moreover, an 88% decrease in the expression levels of PbCDC42 significantly increasesphagocytosis and abrogates virulence of this dimorphic pathogenic fungus in a micemodel.To the best of our knowledge, we provide for the first time genetic evidences that establish thecentral role of polymorphic morphologies in the pathogenesis of P. brasiliensis, thus openingnew therapeutic targets for the treatment of paracoccidioidomycosis.Acknowledgments:Almeida, A.J., Sampaio-Marques, B. and Carvalho, A. were financially supported by a fellowship(SFRH/BPD/33035/2006, SFRH/BI/15406/2005, and SFRH/BD/11837/2003).The work was mostly supported by a grant from FCT, Portugal (POCTI/ESP/45327/2002)and partially by FAPESP, Brazil.91