title: Candida albicans expresses a focal adhesion kinase-like protein that undergoes increased tyrosine phosphorylation upon yeast cell adhesion to vitronectin and the EA.hy 926 human endothelial cell line.
abstract: The signaling pathways triggered by adherence of Candida albicans to the host cells or extracellular matrix are poorly understood. We provide here evidence in C. albicans yeasts of a p105 focal adhesion kinase (Fak)-like protein (that we termed CaFak), antigenically related to the vertebrate p125Fak, and its involvement in integrin-like-mediated fungus adhesion to vitronectin (VN) and EA.hy 926 human endothelial cell line. Biochemical analysis with different anti-chicken Fak antibodies identified CaFak as a 105-kDa protein and immunofluorescence and cytofluorimetric analysis on permeabilized cells specifically stain C. albicans yeasts; moreover, confocal microscopy evidences CaFak as a cytosolic protein that colocalizes on the membrane with the integrin-like VN receptors upon yeast adhesion to VN. The protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A strongly inhibited C. albicans yeast adhesion to VN and EA.hy 926 endothelial cells. Moreover, engagement of alpha v beta 3 and alpha v beta 5 integrin-like on C. albicans either by specific monoclonal antibodies or upon adhesion to VN or EA.hy 926 endothelial cells stimulates CaFak tyrosine phosphorylation that is blocked by PTK inhibitor. A role for CaFak in C. albicans yeast adhesion was also supported by the failure of VN to stimulate its tyrosine phosphorylation in a C. albicans mutant showing normal levels of CaFak and VNR-like integrins but displaying reduced adhesiveness to VN and EA.hy 926 endothelial cells. Our results suggest that C. albicans Fak-like protein is involved in the control of yeast cell adhesion to VN and endothelial cells.
authors.affiliation: Department of Pharmacological Sciences and Experimental Medicine, University of Camerino, 62032 Camerino, Italy. giorgio.santini@unicam.it
authors.forename: Giorgio
authors.initials: G
authors.lastname: Santoni
authors.forename: Roberta
authors.initials: R
authors.lastname: Lucciarini
authors.forename: Consuelo
authors.initials: C
authors.lastname: Amantini
authors.forename: Jordan
authors.initials: J
authors.lastname: Jacobelli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Spreghini
authors.forename: Patrizia
authors.initials: P
authors.lastname: Ballarini
authors.forename: Mario
authors.initials: M
authors.lastname: Piccoli
authors.forename: Angela
authors.initials: A
authors.lastname: Gismondi
mesh_terms: D000942:Antigens, Bacterial / Q000096:biosynthesis; D015703:Antigens, CD / Q000378:metabolism; D002176:Candida albicans / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D039564:Integrin alphaV; D039641:Integrin beta Chains; D039661:Integrin beta3; D016023:Integrins / Q000378:metabolism; D016296:Mutagenesis; D010766:Phosphorylation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D019030:Receptors, Vitronectin / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D019096:Vitronectin / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D015703:Antigens, CD; D039564:Integrin alphaV; D039641:Integrin beta Chains; D039661:Integrin beta3; D016023:Integrins; D010980:Platelet Membrane Glycoproteins; D019030:Receptors, Vitronectin; D019096:Vitronectin; C064660:integrin alphaVbeta5; C084344:integrin beta5; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human