Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, Uttar Pradesh, India.
Int J Dev Biol. 2020;64(4-5-6):331-341. doi: 10.1387/ijdb.190190mt.
Drosophila metamorphosis is associated with substantial metabolic activity involving cell death and cell proliferation leading to differentiation of adult tissues and structures. Unlike other larval tissues, Malpighian tubules (MTs) exhibit apoptotic immunity and do not undergo cell death but are carried over to the adult with some cell reorganisation. They persist despite the fact that they express apoptotic proteins and caspases. In the present study, we analysed the global transcription changes in MTs and compared with salivary glands, to decipher the biology of MTs. Gene set enrichment analysis indicated reduced expression of many ecdysone induced genes, including the critical regulator of cell death, E93 in MTs. We hypothesize that reduction of E93 could be because of over expression of ecdysone oxidase, which is high in MTs and is responsible for regulation of hormone titer by degradation of ecdysone. Ectopic expression of E93 in MTs results in cell death through autophagy. Fork head, which is crucial for survival, is enriched in the MT transcriptome, and its down regulation in MTs could be consequent to over expression of E93. Together our data suggests that the cascade of events initiated by ecdysone mediates survival of MTs through concerted action of multiple factors.
果蝇变态与大量代谢活动有关，包括细胞死亡和细胞增殖，从而导致成年组织和结构的分化。与其他幼虫组织不同，马氏管（MTs）表现出凋亡免疫，不会发生细胞死亡，而是随着一些细胞重组而转移到成年期。尽管它们表达凋亡蛋白和半胱天冬酶，但它们仍然存在。在本研究中，我们分析了 MTs 的全局转录变化，并与唾液腺进行了比较，以阐明 MTs 的生物学特性。基因集富集分析表明，许多蜕皮激素诱导基因的表达减少，包括细胞死亡的关键调节因子 E93 在 MTs 中的表达减少。我们假设 E93 的减少可能是由于蜕皮激素氧化酶的过度表达，该酶在 MTs 中含量很高，负责通过降解蜕皮激素来调节激素滴度。E93 在 MTs 中的异位表达通过自噬导致细胞死亡。叉头，这对于生存至关重要，在 MT 转录组中富集，其在 MTs 中的下调可能是由于 E93 的过度表达。我们的数据表明，由蜕皮激素引发的一系列事件通过多种因素的协同作用介导 MTs 的存活。
