ALKBH5 is a New Mammalian RNA Demethylase

N6-methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as a new mammalian demethylase that oxidatively removes the m6A modification in mRNA in vitro and inside cells. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1552 differentially expressed genes which cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. We show that Alkbh5-deficiency impacts the expression levels of some of these mRNAs, supporting the observed phenotype. The discovery of this new RNA demethylase strongly suggests that the reversible m6A modification plays fundamental and broad functions in mammalian cells. RNA-seq in two cell typesN6-甲基腺嘌呤（N6-methyladenosine, m6A）是高等真核生物中信使RNA（messenger RNA, mRNA）最为普遍的内部修饰形式。本研究报道ALKBH5为一种新型哺乳动物去甲基化酶，可在体外及细胞内通过氧化作用移除mRNA上的m6A修饰。ALKBH5的该去甲基化活性可显著影响mRNA的核质输出、RNA代谢过程，以及核斑中mRNA加工因子的组装。Alkbh5基因敲除的雄性小鼠表现出生育能力受损的表型，其致病机制为凋亡异常影响了减数分裂中期的精母细胞。针对这一表型缺陷，我们在小鼠睾丸中鉴定出1552个差异表达基因，这些基因涵盖广泛的功能类别，其中包含参与p53功能互作网络的精子发生相关mRNA。研究证实，Alkbh5缺失会改变其中部分mRNA的表达水平，为观测到的小鼠表型提供了机制支撑。这一新型RNA去甲基化酶的发现有力表明，可逆的m6A修饰在哺乳动物细胞中发挥着基础性且广泛的生物学功能。本数据集包含两种细胞类型的RNA测序（RNA-seq）数据。