CPH1和EFG1基因在游离态及生物膜态白念珠菌的表达差异

Differential expression of CPH1 and EFG1 genes in planktonic and biofilm Candida albicans

目的检测游离态及不同时期生物膜态白念珠菌转录因子CPH1和EFG1的表达，探讨其在生物膜形成过程中的作用。方法应用激光共聚焦显微镜观察白念珠菌质控株ATCC90028和临床分离株14215于聚乙烯片上黏附生长24h后的生物膜形态。分别提取6株白念珠菌临床分离株13860、13874、14127、14371、14215、14533和质控株ATCC90028游离态以及早期（聚乙烯片上黏附生长4h）、中期（聚乙烯片上黏附生长12h）、晚期（聚乙烯片上黏附生长24h）生物膜态的总RNA，应用荧光定量PCR测定其CPH1和EFG1基因的表达。结果聚乙烯片上黏附生长24h后，激光共聚焦显微镜下可见质控株ATCC90028多为单层的孢子细胞黏附；白念珠菌临床分离株14215形成菌丝态为主，具有三维结构的生物膜。相对于游离态，白念珠菌质控株ATCC90028在生物膜形成的早中晚期转录因子CPH1和EFG1表达均下调。临床分离株转录因子CPH1在游离态、生物膜形成的早中晚期时表达差异均无统计学意义（均P〈0．05）。而与游离态相比，临床分离株转录因子EFG1基因的相对表达量在生物膜形成早期及中期均上调[0．141（0．029-0．212）、0．252（0．103-0．943）比0．077（0．018-0．113），均P〈0．05]，在生物膜形成晚期则无明显改变（P〉0．05），相对表达量为0．091（0．024-0．354）。结论转录因子EFGl在白念珠菌临床分离株生物膜形成过程中有重要的调控作用。

Objective To detect the expression of CPHI and EFG1, the transcription factors, in planktonic stage and various phases during biofilm stage of Candida albicans, and to explore their roles in biofilm formation. Methods Confocal scanning laser microscope was employed for morphological examination of biofihn formation of ATCC90028, the strain for quality control, and the clinically isolated strain 14215 adhering to polyethylene film for 24 hours. The total RNA of 6 clinically isolated strains （13860, 13874, 14127, 14371, 14215 and 14533） and ATCC90028 during planktonic stage, and at early （4-hour adhesion to polyethylene film）, intermediate （ 12-hour adhesion to polyethylene film） and late phase （24-hour adhesion to polyethylene film） during biofilm stage was extracted respectively. Expression of CPH1 and EFGI genes was determined using fluorescent quantitative polymerase chain reaction. Results After the 24-hour adhesion to polyethylene films, the ATCC90028 strain appeared mostly as blastospores in a single layer while the clinically isolated strain 14215 was in the form of hypha producing a three-dimensional biofilm. Expression of CPH1 and EFG1 was down-regulated in the early, intermediate and late phases during biofilm formation, compared with planktonic stage of the ATCC90028 strain. CPH1 expression in the strain14215 did not differ statistically between the planktonic stage and early, intermediate and late phases during biofilm formation （all P〉0.05）. Contrarily, EFG1 expression was up-regulated at early and intermediate stages during biofilm formation as compared with that during planktonic stage [ （0.141 （0.029-0.212） and 0.252（0.103-0.943） vs 0.077 （0.018-0.113）, all P〈0.05], No significant change in EFGI expression was detected at the late phase during biofilm formation [0.091 （0.024- 0.354） , P〉0.05]. Conclusion Transcription factor EFG1 may play a critical role in the regulation of biofilm formation in clinically isolated Candida albicans strains.