Analyses of G-protein mediated signals on the organization of the actin cytoskeleton, polar cell growth and the pathogenicity of Candida albicans

Rho家族的GTP结合蛋白是肌动蛋白-细胞骨架结构的重要调节因子，决定着真核细胞的形态和生长极性。G-蛋白信号传导对于双态转换是必需的，即人类真菌病原体白色念珠菌从酵母样生长到菌丝生长的变化，这是其毒力所必需的。我们可以表明，Cawal 1基因编码的Wiskott-Aldrich综合征样蛋白是至关重要的菌丝的发展和致病性的白色念珠菌。然而，Cawal 1突变体在诱导条件下仍然能够出芽并形成假菌丝。这种能力表明存在复杂的相互作用的信号传导途径，这将使用显性负性或组成型活性G蛋白和其他潜在的Rho信号传导介质的功能分析，特别是福尔马林同系物或抑制剂的Cawal 1表型进行分析。通过在体内的时间推移和高分辨率荧光显微镜（使用GFP标记的蛋白质），这些蛋白质的亚细胞蛋白定位在白色念珠菌细胞/菌丝随时间的推移被记录，以确定细胞极性建立和极化菌丝生长的过程是如何连接和相互协调的白色念珠菌。

GTP-binding proteins of Rho-family are central regulators of actin-cytoskeletal organization and thus determine cell shape and growth polarity of eukaryotic cells. G-protein signaling is essential for the dimorphic switch i.e. the change from yeastlike growth to hyphal growth of the human fungal pathogen Candida albicans which is required for its virulence. We could show that the Cawal 1 gene which encodes a Wiskott-Aldrich Syndrome-like protein is of key importance for the development of hyphae and the pathogenicity of C.albicans. Cawal1 mutants, however, are still able to bud and form pseudohyphae under inducing conditions. This ability suggests the presence of complex interacting signaling pathways which will be analyzed using dominant negative or constitutively active G-proteins and functional analyses of other potential mediators of Rho-signaling, particularly of formin-homologs or suppressors of the Cawal1 phenotype. Via in vivo time lapse and high-resolution fluorescence microscopy (using GFP-tagged proteins) subcellular protein localization of these proteins in C.albicans cells/hyphae over time is recorded to determine how processes of cell polarity establishment and polarized hyphal growth are linked and coordinated with each other in C.albicans.