Hyphal Orientation of Candida albicans Is Regulated by a Calcium-Dependent Mechanism

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• 作者：Alex ; ra Br ; Scott Shanks ; Vanessa M.S. Duncan ; Meng Yang ; Kevin Mackenzie ; Neil A.R. Gow
• 关键词：MICROBIO ; SIGNALING
• 刊名：Current Biology
• 出版年：2007
• 出版时间：20 February 2007
• 年：2007
• 卷：17
• 期：4
• 页码：347-352
• 全文大小：495 K

文摘

Eukaryotic cells from fungal hyphae to neurites that grow by polarized extension must coordinate cell growth and cell orientation to enable them to exhibit growth tropisms and to respond to relevant environmental cues. Such cells generally maintain a tip-high Ca²⁺ cytoplasmic gradient, which is correlated with their ability to exhibit polarized tip growth and to respond to growth-directing extracellular signals 1, 2, 3, 4 and 5. In yeast and other fungi, the polarisome, exocyst, Arp2/3, and Spitzenkörper protein complexes collectively orchestrate tip growth and cell polarity, but it is not clear whether these molecular complexes also regulate cell orientation or whether they are influenced by cytoplasmic Ca²⁺ gradients. Hyphae of the human pathogenic fungus Candida albicans reorient their growth axis in response to underlying surface topography (thigmotropism) [6] and imposed electric fields (galvanotropism) [7]. The establishment and maintenance of directional growth in relation to these environmental cues was Ca²⁺ dependent. Tropisms were attenuated in media containing low Ca²⁺, or calcium-channel blockers, and in mutants where calcium channels or elements of the calcium signaling pathway were deleted. Therefore galvanotropism and thigmotropism may both be mediated by localized Ca²⁺ influx at sites of polarized growth via Ca²⁺ channels that are activated by appropriate environmental signals.