RNA甲基化修饰调控和规律

表观遗传学修饰包括DNA、RNA和蛋白质的化学修饰,基于非序列改变所致基因表达和功能水平变化。近年来,在DNA和蛋白质修饰基础上,可逆RNA甲基化修饰研究引领了第3次表观遗传学修饰研究的浪潮。RNA存在100余种化学修饰,甲基化是最主要的修饰形式。鉴定RNA甲基化修饰酶及研发其转录组水平高通量检测技术,是揭示RNA化学修饰调控基因表达和功能规律的基础。本文主要总结了近年来本课题组与合作团队及国内外同行在RNA甲基化表观转录组学研究中取得的主要前沿进展,包括发现了RNA去甲基酶、甲基转移酶和结合蛋白,揭示RNA甲基化修饰调控RNA加工代谢,及其调控正常生理和异常病理等重要生命进程。这些系列研究成果证明RNA甲基化修饰类似于DNA甲基化,具有可逆性,拓展了RNA甲基化表观转录组学研究新领域,完善了中心法则表观遗传学规律。

A neural m^(6)A pathway regulates behavioral aggregation in migratory locusts

RNA N6-methyladenosine(m^(6)A),as the most abundant modification of messenger RNA,can modulate insect behaviors,but its specific roles in aggregation behaviors remain unexplored.Here,we conducted a comprehensive molecular and physiological characterization of the individual components of the methyltransferase and demethylase in the migratory locust Locusta migratoria.Our results demonstrated that METTL3,METTL14 and ALKBH5 were dominantly expressed in the brain and exhibited remarkable responses to crowding or isolation.The individual knockdown of methyltransferases(i.e.,METTL3 and METTL14)promoted locust movement and conspecific attraction,whereas ALKBH5 knockdown induced a behavioral shift toward the solitary phase.Furthermore,global transcriptome profiles revealed that m^(6)A modification could regulate the orchestration of gene expression to fine tune the behavioral aggregation of locusts.In summary,our in vivo characterization of the m^(6)A functions in migratory locusts clearly demonstrated the crucial roles of the m^(6)A pathway in effectively modulating aggregation behaviors.

m^6A Regulates Neurogenesis and Neuronal Development by Modulating Histone Methyltransferase Ezh2

N6-methyladenosine (m6A),catalyzed by the methyltransferase complex consisting of Mettl3 and Mettl14,is the most abundant RNA modification in mRNAs and participates in diverse biological processes. However,the roles and precise mechanisms of m6A modification in regulating neuronal development and adult neurogenesis remain unclear. Here,we examined the function of Mettl3,the key component of the complex,in neuronal development and adult neurogenesis of mice. We found that the depletion of Mettl3 significantly reduced m6A levels in adult neural stem cells (aNSCs) and inhibited the proliferation of aNSCs. Mettl3 depletion not only inhibited neu-ronal development and skewed the differentiation of aNSCs more toward glial lineage,but also affected the morphological maturation of newborn neurons in the adult brain. m6A immunoprecip-itation combined with deep sequencing (MeRIP-seq) revealed that m6A was predominantly enriched in transcripts related to neurogenesis and neuronal development. Mechanistically,m6A was present on the transcripts of histone methyltransferase Ezh2,and its reduction upon Mettl3 knockdown decreased both Ezh2 protein expression and consequent H3K27me3 levels. The defects of neurogenesis and neuronal development induced by Mettl3 depletion could be rescued by Ezh2 overexpression. Collectively,our results uncover a crosstalk between RNA and histone modifica-tions and indicate that Mettl3-mediated m6A modification plays an important role in regulating neurogenesis and neuronal development through modulating Ezh2.

5-Hydroxymethylome in Circulating Cell-free DNA as A Potential Biomarker for Non-small-cell Lung Cancer

Non-small-cell lung cancer （NSCLC）, the most common type of lung cancer accounting for 85% of the cases, is often diagnosed at advanced stages owing to the lack of efficient early diagnostic tools. 5-Hydroxymetbylcytosine （ShmC） signatures in circulating cell-free DNA （cfDNA） that carries the cancer-specific epigenetic patterns may represent the valuable biomarkers for discriminat- ing tumor and healthy individuals, and thus could be potentially useful for NSCLC diagnosis. Here, we employed a sensitive and reliable method to map genome-wide 5hmC in the cfDNA of Chinese NSCLC patients and detected a significant 5hmC gain in both the gene bodies and promoter regions in the blood samples from tumor patients compared with healthy controls. Specifically, we identi- fied six potential biomarkers from 66 patients and 67 healthy controls （mean decrease accuracy 〉 3.2, P 〈 3.68E-19） using machine-learning-based tumor classifiers with high accuracy. Thus, the unique signature of 5hmC in tumor patient＇s cfDNA identified in our study may provide valuable information in facilitating the development of new diagnostic and therapeutic modalities for NSCLC.

Epitranscriptomic 5-Methylcytosine Profile in PM_(2.5)-induced Mouse Pulmonary Fibrosis

Exposure of airborne particulate matter(PM)with an aerodynamic diameter less than 2.5μm(PM2.5)is epidemiologically associated with lung dysfunction and respiratory symptoms,including pulmonary fibrosis.However,whether epigenetic mechanisms are involved in PM2.5-induced pulmonary fibrosis is currently poorly understood.Herein,using a PM2.5-induced pulmonary fibrosis mouse model,we found that PM2.5 exposure leads to aberrant mRNA5-methylcytosine(m5C)gain and loss in fibrotic lung tissues.Moreover,we showed the m5C-mediated regulatory map of gene functions in pulmonary fibrosis after PM2.5 exposure.Several genes act as m5C gain-upregulated factors,probably critical for the development of PM2.5-induced fibrosis in mouse lungs.These genes,including Lcn2,Mmp9,Chi3l1,Adipoq,Atp5j2,Atp5l,Atpif1,Ndufb6,Fgr,Slc11 a1,and Tyrobp,are highly related to oxidative stress response,inflammatory responses,and immune system processes.Our study illustrates the first epitranscriptomic RNA m5C profile in PM2.5-induced pulmonary fibrosis and will be valuable in identifying biomarkers for PM2.5 exposure-related lung pathogenesis with translational potential.