Santoni Giorgio, Lucciarini Roberta, Amantini Consuelo, Jacobelli Jordan, Spreghini Elisabetta, Ballarini Patrizia, Piccoli Mario, Gismondi Angela
Department of Pharmacological Sciences and Experimental Medicine, University of Camerino, 62032 Camerino, Italy.
Infect Immun. 2002 Jul;70(7):3804-15. doi: 10.1128/IAI.70.7.3804-3815.2002.
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.
白色念珠菌黏附于宿主细胞或细胞外基质所触发的信号通路目前仍知之甚少。我们在此提供证据,表明白色念珠菌酵母中存在一种与脊椎动物p125Fak抗原相关的p105黏着斑激酶(Fak)样蛋白(我们将其命名为CaFak),以及它参与整合素样介导的真菌对玻连蛋白(VN)和EA.hy 926人内皮细胞系的黏附。用不同的抗鸡Fak抗体进行生化分析,确定CaFak为一种105 kDa的蛋白,对透化细胞进行免疫荧光和细胞荧光分析可特异性地对白色念珠菌酵母进行染色;此外,共聚焦显微镜显示CaFak是一种胞质蛋白,在酵母黏附于VN时,它与整合素样VN受体在膜上共定位。蛋白酪氨酸激酶(PTK)抑制剂染料木黄酮和除莠霉素A强烈抑制白色念珠菌酵母对VN和EA.hy 926内皮细胞的黏附。此外,通过特异性单克隆抗体或在黏附于VN或EA.hy 926内皮细胞时,白色念珠菌上的αvβ3和αvβ5整合素样分子的结合会刺激CaFak酪氨酸磷酸化,而这种磷酸化会被PTK抑制剂阻断。在一个CaFak和VNR样整合素水平正常但对VN和EA.hy 926内皮细胞黏附性降低的白色念珠菌突变体中,VN未能刺激其酪氨酸磷酸化,这也支持了CaFak在白色念珠菌酵母黏附中的作用。我们的结果表明,白色念珠菌Fak样蛋白参与控制酵母细胞对VN和内皮细胞的黏附。