State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Ningbo University, PR China.
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Ningbo University, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China.
Biochim Biophys Acta Gene Regul Mech. 2023 Jun;1866(2):194927. doi: 10.1016/j.bbagrm.2023.194927. Epub 2023 Mar 16.
N6-methyladenosine (m6A) plays an important role in regulating many physiological and disease processes in vertebrates, in which methyltransferase-like 3 (METTL3) is the best-known m6A methyltransferase. However, the functional roles of invertebrate METTL3 have not yet been highlighted. In this study, we found that METTL3 from Apostichopus japonicus (AjMETTL3) was significantly induced in coelomocytes accompanied by higher levels of m6A modification in response to Vibrio splendidus challenge. Overexpression or silencing of AjMETTL3 in coelomocytes increased or decreased the m6A levels and promoted or inhibited V. splendidus-induced coelomocyte apoptosis, respectively. To further explore the molecular mechanism of AjMETTL3-mediated coelomic immunity, m6A-seq analysis revealed that the endoplasmic reticulum-related degradation (ERAD) pathway was significantly enriched, in which suppressor/enhancer of Lin-12-like (AjSEL1L) was suggested to be a target of AjMETTL3 in a negative regulatory manner. Functional analysis revealed that the increased AjMETTL3 reduced the stability of AjSEL1L mRNA by targeting the m6A modification site of 2004 bp-GGACA-2008 bp. The decreased AjSEL1L was further confirmed to be involved in AjMETTL3-mediated coelomocyte apoptosis. Mechanistically, the inhibited AjSEL1L increased the transcription of AjOS9 and Ajp97 in the EARD pathway to promote ubiquitin protein accumulation and ER stress, which further activated AjPERK-AjeIF2α pathway dependent coelomocyte apoptosis, but not the AjIRE1 or AjATF6 pathway. Taken together, our results supported invertebrate METTL3-mediated coelomocyte apoptosis by regulating the PERK-eIF2α pathway.
N6-甲基腺苷（m6A）在脊椎动物的许多生理和疾病过程中发挥着重要作用，其中甲基转移酶样 3（METTL3）是最著名的 m6A 甲基转移酶。然而，无脊椎动物 METTL3 的功能作用尚未得到强调。在这项研究中，我们发现，刺参（Apostichopus japonicus）的 METTL3（AjMETTL3）在腔细胞中显著诱导，伴随着更高水平的 m6A 修饰，以响应灿烂弧菌的挑战。在腔细胞中过表达或沉默 AjMETTL3 分别增加或降低了 m6A 水平，并促进或抑制了灿烂弧菌诱导的腔细胞凋亡。为了进一步探讨 AjMETTL3 介导的体腔免疫的分子机制，m6A-seq 分析显示内质网相关降解（ERAD）途径显著富集，其中抑制 Lin-12 样（AjSEL1L）被认为是 AjMETTL3 以负调控方式的靶标。功能分析表明，增加的 AjMETTL3 通过靶向 2004 bp-GGACA-2008 bp 的 m6A 修饰位点减少了 AjSEL1L mRNA 的稳定性。进一步证实减少的 AjSEL1L 参与了 AjMETTL3 介导的腔细胞凋亡。在机制上，抑制的 AjSEL1L 增加了 ERAD 途径中的 AjOS9 和 Ajp97 的转录，以促进泛素蛋白积累和内质网应激，从而进一步激活了依赖 AjPERK-AjeIF2α 途径的腔细胞凋亡，但不激活 AjIRE1 或 AjATF6 途径。总之，我们的结果支持无脊椎动物 METTL3 通过调节 PERK-eIF2α 途径介导腔细胞凋亡。
