Department of Immunology and Cell Biology, Vilnius University, Institute of Biotechnology, Vilnius, Lithuania.
Thermo Fisher Scientific, Vilnius, Lithuania.
Exp Cell Res. 2019 Jul 1;380(1):29-35. doi: 10.1016/j.yexcr.2019.04.015. Epub 2019 Apr 17.
The removal of introns from mRNA precursors (pre-mRNAs) is an essential step in eukaryotic gene expression. The splicing machinery heavily contributes to biological complexity and especially to the ability of cells to adapt to altered cellular conditions. Hypoxia also plays a key role in the pathophysiology of many disease states. Recent studies have revealed that tumorigenesis and hypoxia involve large-scale alterations in alternative pre-mRNA splicing. Cancer associated Fas protein plays a central role in the physiological regulation of programmed cell death and has been implicated in the pathogenesis of various malignancies and diseases of the immune system. Fas pre-mRNA is alternatively spliced by excluding exon 6 to produce soluble Fas (sFas) protein that lacks a transmembrane domain and acts by inhibiting Fas mediated apoptosis. Another cancer related protein Rac1 plays an important regulatory role specifically in cells' motility, growth and survival. Rac pre-mRNA is alternatively spliced to produce Rac1b protein, which is upregulated in metastatic diseases. In the present study we, for the first time, show that anti-apoptotic Fas mRNA isoform formation is regulated by cellular microenvironment - hypoxia. Hypoxic microenvironment, however, does not influence Rac1 pre-mRNAs alternative splicing. Also our presented results indicate that splicing factors hnRNP A1 and SPF45, previously shown to regulate Fas alternative splicing in normoxic cells, are not involved in hypoxia dependent alternative Fas pre-mRNA splicing regulation in an amount dependent manner. Our observations on hypoxia dependent alternative Fas pre-mRNA splicing regulation indicate a probable involvement of other, yet unidentified splicing factors. Presented data also shows the contribution of pre-mRNA splicing to cell survival under unfavorable conditions.
外显子从 mRNA 前体（pre-mRNA）中的去除是真核生物基因表达的一个必要步骤。剪接机制对生物复杂性有很大的贡献，尤其是对细胞适应细胞变化的能力有很大的贡献。缺氧在许多疾病状态的病理生理学中也起着关键作用。最近的研究表明，肿瘤发生和缺氧涉及到替代 pre-mRNA 剪接的大规模改变。肿瘤相关 Fas 蛋白在程序性细胞死亡的生理调节中起着核心作用，并与各种恶性肿瘤和免疫系统疾病的发病机制有关。Fas pre-mRNA 通过排除外显子 6 进行选择性剪接，产生缺乏跨膜结构域的可溶性 Fas（sFas）蛋白，通过抑制 Fas 介导的细胞凋亡起作用。另一种与癌症相关的蛋白 Rac1 特异性地在细胞的运动性、生长和存活中发挥重要的调节作用。Rac pre-mRNA 被选择性剪接产生 Rac1b 蛋白，在转移性疾病中上调。在本研究中，我们首次表明，抗凋亡 Fas mRNA 同工型的形成受细胞微环境 - 缺氧的调节。然而，缺氧微环境并不影响 Rac1 pre-mRNA 的选择性剪接。我们呈现的结果还表明，hnRNP A1 和 SPF45 等先前被证明在常氧细胞中调节 Fas 选择性剪接的剪接因子，不以依赖于数量的方式参与缺氧依赖的 Fas pre-mRNA 选择性剪接调节。我们对缺氧依赖的 Fas pre-mRNA 选择性剪接调节的观察表明，可能涉及其他尚未确定的剪接因子。目前的数据还表明，在不利条件下，pre-mRNA 剪接有助于细胞存活。
