Département de biologie et Centre de recherche avancée en génomique environnementale, Université d'Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Département de biologie et Centre de recherche avancée en génomique environnementale, Université d'Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Gene. 2019 Feb 5;684:70-75. doi: 10.1016/j.gene.2018.10.061. Epub 2018 Oct 23.
The human genome contains an unusually large number of processed pseudogenes. The fact that processed pseudogenes are roughly 33% more abundant in our X chromosome than in our autosomes suggests that this overabundance is the result of the fact that human oogenesis is much longer than that of non-mammalian species. Here, we analyze the origins of the processed pseudogenes found on the human Y chromosome to determine whether human spermatogenesis also contribute to this overabundance. Our results show that human processed pseudogenes not only retrotranspose to the Y chromosome, but are also produced by genes on the Y chromosome. Furthermore, the fact that X chromosomes are three times more abundant than Y chromosomes likely explains why the euchromatic density of processed pseudogenes is three times higher in the X chromosome than in the Y chromosome. The large number of processed pseudogenes found in our genome is therefore due to the low substrate specificity of the L1 reverse transcriptase responsible for the reverse transcription of germline mRNA molecules into processed pseudogenes, as well as the life-long production of both male and female gametes.
人类基因组包含大量异常的加工假基因。事实上，在人类 X 染色体中，加工假基因的丰度比常染色体高约 33%，这表明这种过剩是人类卵母细胞发生时间远长于非哺乳动物物种的结果。在这里，我们分析了在人类 Y 染色体上发现的加工假基因的起源，以确定人类精子发生是否也促成了这种过剩。我们的结果表明，人类加工假基因不仅会逆转录到 Y 染色体上，而且还由 Y 染色体上的基因产生。此外，X 染色体的丰度是 Y 染色体的三倍，这很可能解释了为什么在 X 染色体上，加工假基因的常染色质密度比在 Y 染色体上高 3 倍。我们基因组中发现的大量加工假基因是由于负责将生殖系 mRNA 分子逆转录成加工假基因的 L1 逆转录酶的底物特异性低，以及男性和女性配子的终生产生所致。
