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Abstract：
N6-methyladenosine (m6A) is the most prevalent type of RNA modification. METTL3 in the methyltransferase complex is the core enzyme responsible for methylation. METTL3 selectively catalyzes the adenosines centered in the RRAC motif. Functional studies established that m6A could enhance the translation efficiency (TE) of modified genes by recruiting reader protein YTHDF1 and other initiation factors. We downloaded the m6A peaks in HeLa cells from a previous study and defined the m6A modified genes and sites. Ancestral mutations in the genic region fixed in the HeLa cell samples were defined using their mRNA-Seq data and the alignment between human and mouse genomes. Furthermore, in the small interfering (si)-METTL3 sample, the calculated TE foldchange of all genes was compared to that in the negative control. The TE of m6A genes was globally down-regulated in si-METTL3 versus control compared to the non-m6A genes. In m6A modified genes, RRAC motif mutations were suppressed compared to mutations in non-motif regions or non-m6A genes. Among the m6A genes, a fraction RRAC motif mutations negatively correlated with the TE foldchange (si-METTL3 versus control). The TE of m6A modified genes was enhanced in HeLa cells. RRAC motif mutations could potentially prevent methylation of adenosines and consequently abolish the enhanced translation. Such mutations in the RRAC motif might be deleterious. Accordingly, we observed lower fractions of mutations in RRAC motifs than in other regions. This prevention of mutations in the RRAC motif could be a strategy adopted by cancer cells to maintain the elevated translation of particular genes.
摘要：
N6-甲基腺苷(m6A)是最普遍的RNA修饰类型。甲基转移酶复合物中的METTL3是负责甲基化的核心酶。METTL3选择性催化以RRAC基序为中心的腺苷。功能研究表明，m6A可以通过招募读者蛋白YTHDF1和其他起始因子来提高修饰基因的翻译效率（TE）。我们从先前的研究中下载了HeLa细胞中的m6A峰，并定义了m6A修饰的基因和位点。使用其mRNA-Seq数据以及人和小鼠基因组之间的比对来定义HeLa细胞样品中固定的基因区域中的祖先突变。此外，在小干扰(si)-METTL3样品中，将计算出的所有基因的TE折叠变化与阴性对照进行比较。与非m6A基因相比,m6A基因的TE在si-METTL3中相对于对照而言是整体下调的。在m6A修饰基因中，与非基序区域或非m6A基因中的突变相比,RRAC基序突变被抑制。在m6A基因中，部分RRAC基序突变与TE折叠呈负相关(si-METTL3与对照)。在HeLa细胞中m6A修饰基因的TE增强。RRAC基序突变可能会阻止腺苷的甲基化，从而消除增强的翻译。RRAC基序中的此类突变可能是有害的。因此，我们观察到RRAC基序的突变分数低于其他区域。RRAC基序中突变的这种预防可能是癌细胞维持特定基因翻译升高的策略。
