The Drosophila ribosome protein S5 paralog RpS5b promotes germ cell and follicle cell differentiation during oogenesis
The Drosophila ribosome protein S5 paralog RpS5b promotes germ cell and follicle cell differentiation during oogenesis
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果蝇核糖体蛋白S5 partial RpS5b在卵子发生过程中促进生殖细胞和卵泡细胞分化
DOI：
10.1242/dev.199511
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发表时间：
2021-10-01
期刊：
影响因子：
4.6
通讯作者：
Buszczak, Michael
中科院分区：
文献类型：
--
作者：
Jang, Seoyeon;Lee, Jeon;Buszczak, Michael
新出现的证据表明，核糖体异质性可能对不同细胞类型和各种条件下特定mRNA的翻译产生重要的功能影响。核糖体异质性有多种形式，包括核糖体蛋白（RP）的翻译后修饰、特定RP的缺失以及包含不同RP旁系同源物。果蝇基因组编码两个RpS 5旁系同源物：RpS 5a和RpS 5 b。虽然RpS 5a是普遍表达的，但RpS 5 b在生殖系统中表现出富集表达。RpS 5 b的缺失导致雌性不育，其特征在于卵室在7-8期发育停滞，卵黄发生中断和后卵泡细胞（PFC）增生。虽然转基因拯救实验表明RpS 5a和RpS 5 b之间存在功能冗余，但分子、生物化学和ribo-seq实验表明RpS 5 b突变体显示rRNA转录和RP产生增加，伴随着蛋白质合成增加。RpS 5 b的缺失导致基于微管的缺陷以及Delta和Mindbombl的错误定位，导致PFC中Notch途径活化失败。总之，我们的研究结果表明，生殖细胞特异性表达RpS 5 b促进适当的卵室发育，确保功能性核糖体的稳态。
Emerging evidence suggests that ribosome heterogeneity may have important functional consequences in the translation of specific mRNAs within different cell types and under various conditions. Ribosome heterogeneity comes in many forms, including post-translational modification of ribosome proteins (RPs), absence of specific RPs and inclusion of different RP paralogs. The Drosophila genome encodes two RpS5 paralogs: RpS5a and RpS5b. While RpS5a is ubiquitously expressed, RpS5b exhibits enriched expression in the reproductive system. Deletion of RpS5b results in female sterility marked by developmental arrest of egg chambers at stages 7-8, disruption of vitellogenesis and posterior follicle cell (PFC) hyperplasia. While transgenic rescue experiments suggest functional redundancy between RpS5a and RpS5b, molecular, biochemical and ribo-seq experiments indicate that RpS5b mutants display increased rRNA transcription and RP production, accompanied by increased protein synthesis. Loss of RpS5b results in microtubule-based defects and in mislocalization of Delta and Mindbombl, leading to failure of Notch pathway activation in PFCs. Together, our results indicate that germ cell-specific expression of RpS5b promotes proper egg chamber development by ensuring the homeostasis of functional ribosomes.