激肽原基因的选择性剪接与功能研究进展

激肽原基因在不同物种中有一定的差异, 其编码的蛋白质产物也有所不同。在人类、牛和小鼠中存在的激肽原基因K是一种选择性剪接基因, 其可以编码两种激肽原产物, 而在大鼠中, 除了激肽原基因K之外还有一类激肽原基因T, 其只能编码一种激肽原。激肽原属于半胱氨酸蛋白酶抑制剂超家族中家族3的成员, 是一类具有多个结构域的多功能蛋白, 在人体内多种功能协同作用, 维持着机体的正常生理状态。激肽原的凝血和抗凝血两种相互拮抗的功能既能使破损的血管得到修复, 防止流血不止, 又能抑制血管内血栓的形成。本文将对目前研究较多的人、牛、小鼠和大鼠的激肽原基因的选择性剪接以及激肽原的凝血、抗凝血等多方面的功能做一综述, 为更进一步地阐明激肽原基因的进化机制, 加深对基因选择性剪接机制的了解, 揭示激肽原功能的认识等方面有所启示, 并为调节血管通透性、调节血压和抗肿瘤等新药的开发提供有益的参考。     

Molecular Profiling of DNA Methylation and Alternative Splicing of Genes in Skeletal Muscle of Obese Rabbits

DNA methylation and the alternative splicing of precursor messenger RNAs (pre-mRNAs) are two important genetic modification mechanisms. However, both are currently uncharacterized in the muscle metabolism of rabbits. Thus, we constructed the Tianfu black rabbit obesity model (obese rabbits fed with a 10% high-fat diet and control rabbits from 35 days to 70 days) and collected the skeletal muscle samples from the two groups for Genome methylation sequencing and RNA sequencing. DNA methylation data showed that the promoter regions of 599 genes and gene body region of 2522 genes had significantly differential methylation rates between the two groups, of which 288 genes had differential methylation rates in promoter and gene body regions. Analysis of alternative splicing showed 555 genes involved in exon skipping (ES) patterns, and 15 genes existed in differential methylation regions. Network analysis showed that 20 hub genes were associated with ubiquitinated protein degradation, muscle development pathways, and skeletal muscle energy metabolism. Our findings suggest that the two types of genetic modification have potential regulatory effects on skeletal muscle development and provide a basis for further mechanistic studies in the rabbit.     

多聚嘧啶区结合蛋白1通过调控基因的可变剪接促进胆管癌细胞的生长、迁移及侵袭能力

胆管癌是一种起病隐匿、侵袭性强、致死率高的原发性恶性肿瘤。多聚嘧啶区结合蛋白1(polypyrimidine tract-binding protein 1, PTBP1)已被报道,在多种类型肿瘤组织中异常高表达并参与癌症进展,但其在胆管癌中的作用仍未见报道。该研究旨在探讨PTBP1在胆管癌中的生物学功能,并初步解析其分子机制。本文利用公开的癌症基因组图谱(the cancer genome atlas, TCGA)数据,分析了胆管癌及癌旁组织中的PTBP1 mRNA表达水平。结果显示,PTBP1在胆管癌组织中的表达水平显著高于癌旁组织(P < 0.05)。随后,在胆管癌细胞系RBE和HuH28中,通过CCK-8和细胞平板克隆实验,评价了PTBP1对胆管癌细胞生长能力的影响。结果显示,过表达PTBP1可显著促进胆管癌细胞的生长(P < 0.01),而敲低PTBP1显著抑制胆管癌细胞的生长(P < 0.001)。Transwell和Invasion实验结果显示,过表达PTBP1可显著促进胆管癌细胞的迁移和侵袭(P < 0.001),而敲低PTBP1显著抑制胆管癌细胞的迁移和侵袭(P < 0.001)。转录物组测序和通路富集分析结果显示,在胆管癌细胞中,敲低PTBP1后上调表达的基因显著富集于p53信号通路;而下调表达的基因显著富集于胆固醇代谢、Rho GTPase和TGF-β等信号通路。基于上述转录物组测序数据,本文还分析发现,敲低PTBP1可导致一系列基因发生异常的mRNA可变剪接事件,例如参与TGF-β调控的TGIF1及与p53活性相关的GNAS基因等。综上所述,PTBP1可能通过调控一系列基因的可变剪接而影响多个癌症相关的信号通路,从而促进胆管癌的进展。