探討剔除RHD3對白色念珠菌型態變化之影響

Abstract

白色念珠菌為伺機性感染之病源菌，在健康的人體中共生於皮膚、腸胃道和生殖道黏膜表面。對於免疫功能不全的個體，則可能會造成疾病。目前的研究已知白色念珠菌的型態轉變能力和致病力有相關性，先前本實驗室比對過非致病株HLC54 (cph1/cph1 efg1/efg1)和野生株SC5314的基因表現情形，發現RHD3的表現量在HLC54中遠大於野生株，因此想要探討RHD3和型態轉變以及致病力之間的關聯性。對於RHD3的研究目前已知其存在於細胞壁上，為GPI-anchored protein，且大量出現在酵母菌型的細胞壁中。但對於RHD3在白色念珠菌的型態轉變中所扮演的角色和功能依舊不清楚。因此希望藉由剔除rhd3和提高RHD3的表現量，來觀察白色念珠菌的變化，藉以推測RHD3在白色念珠菌中可能的功能和角色。使用的策略有利用營養基因和SAT1 flipper cassette當作篩選標記，進行RHD3的剔除。以及使用tetracycline-regulated promoter和ACT1 promoter進行RHD3的過量表現。結果在過量表現RHD3的部分，RHD3的表現量約等同於野生株，並未提高接近HLC54中的表現量。而RHD3的剔除不影響白色念珠菌的型態轉變。

Candida albicans is an opportunistic pathogen. It is commensal on human skin, gastrointestinal and genitourinary tract in healthy individuals. However, it can cause diseases in immunocompromised people. The pathogenicity of C. albicans is related to its ability of yeast-hyphae transition. Previous expression profiling study has showed that RHD3 has higher expression in cph1/cph1 efd1/efg1 avirulent mutant than in the wild-type, SC5314. Therefore, RHD3 might be related to the ability of transition or virulence. RHD3 is a GPI-anchored protein located at cell surface, especially on cell wall. And it is abundant in yeast form C. albicans cell. However, the role of RHD3 in C. albicans is not clear. Therefore, I try to delete RHD3 with nutrient markers as well as SAT1 flipper cassette, and to over-express RHD3 by tetracycline-regulated promoter and ACT1 promoter. The results showed that the expression level in over-expression mutants remained similar to that of wild-type, and the null mutations did not affect the morphogenesis of the C. albicans.