抗菌肽CGA-N12降低热带念珠菌线粒体膜电位机制初步研究

发布时间：2018-09-11 10:55

【摘要】：真菌感染尤其是深部真菌感染的发病率逐年攀升。致病菌反复或者持续暴露在常用抗生素下就会对这些抗菌药物产生耐药性。抗菌肽因安全性高、抗菌谱广、不易产生耐药性等优点,而被广泛研究,可能成为传统抗生素的替代品。CGA-N12是抗菌肽CGA-N46羧基端12个氨基酸组成的衍生物。前期研究表明,CGA-N12具有与CGA-N46相似的抗念珠菌作用机制,即降低线粒体膜电位。CGA-N12作为CGA-N46的衍生物,与CGA-N46相比,抗念珠菌活性提高,且敏感菌由克柔念珠菌转换为临床意义更大的热带念珠菌。进一步研究CGA-N12降低线粒体膜电位的分子作用机制,对将其开发成新型抗菌药物具有重要意义。线粒体通透性转换孔(mitochondrial permeability transition pore,mPTP),调节着线粒体膜通透性。当mPTP处于打开状态时,线粒体膜通透性增加,膜电位降低,Ca2+泄露、细胞色素c释放。本文利用差速离心法从热带念珠菌菌体内提取出活性离体线粒体,分别用mPTP打开抑制剂CsA、mPTP打开促进剂Nd(III)作对照,判断CGA-N12对线粒体膜通透性的影响。结果表明:CGA-N12对线粒体的影响类似于mPTP打开促进剂Nd(III),诱导线粒体通透性提高,使线粒体肿胀、膜电位降低、Ca2+泄露、细胞色素c释放。为进一步研究CGA-N12促进mPTP打开的分子作用机制,我们研究了CGA-N12对mPTP打开抑制剂CsA和DTT处理后的线粒体通透性的影响,研究结果表明CGA-N12消除了CsA和DTT抑制mPTP打开的作用。因此,CGA-N12可能通过作用于CsA和DTT的作用靶点,亦或采用其他作用机制,使线粒体通透性提高。综上所述,CGA-N12通过使线粒体通透性增加导致线粒体膜电位降低,其促进线粒体通透性增加的机制需进一步探讨。
[Abstract]:The incidence of fungal infections, especially deep fungal infections, is increasing year by year. Repeated or sustained exposure to common antibiotics can result in resistance to these antibiotics. Because of its high safety, wide antimicrobial spectrum and low resistance to antibiotics, antimicrobial peptides have been widely studied and may be used as substitutes for traditional antibiotics. CGA-N12 is a derivative of 12 amino acids at the carboxyl terminal of CGA-N46. Previous studies have shown that CGA-N12 has a mechanism similar to that of CGA-N46, that is to say, the mitochondrial membrane potential. CGA-N12 is a derivative of CGA-N46. Compared with CGA-N46, the activity of CGA-N12 is higher than that of CGA-N46. And the sensitive bacteria were transformed from Candida crurus to Candida tropicalis with greater clinical significance. Further study on the molecular mechanism of CGA-N12 decreasing mitochondrial membrane potential is of great significance for the development of novel antimicrobial agents. Mitochondrial permeability transition pore (mitochondrial permeability transition pore,mPTP) regulates mitochondrial membrane permeability. When mPTP was on, mitochondrial membrane permeability increased, membrane potential decreased and Ca 2 2 leakage, cytochrome c released. In this paper, the active mitochondria were isolated from Candida tropicalis by differential centrifugation, and the effect of CGA-N12 on mitochondrial membrane permeability was evaluated by CsA,mPTP opening accelerator (Nd (III), a mPTP opening inhibitor. The results showed that the effect of 1: CGA-N12 on mitochondria was similar to that of Nd (III), a mPTP opening accelerator, which increased mitochondrial permeability, caused mitochondrial swelling, decreased membrane potential, and released cytochrome c. In order to further study the molecular mechanism of CGA-N12 promoting the opening of mPTP, we studied the effect of CGA-N12 on mitochondrial permeability after treatment with mPTP opening inhibitor CsA and DTT. The results showed that CGA-N12 eliminated the inhibitory effect of CsA and DTT on mPTP opening. Therefore, CGA-N12 may increase mitochondrial permeability by targeting CsA and DTT, or by other mechanisms. In conclusion, CGA-N12 leads to the decrease of mitochondrial membrane potential by increasing mitochondrial permeability. The mechanism of CGA-N12 promoting the increase of mitochondrial permeability needs to be further explored.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R978

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