Daiki Kitamura, Kiichiro Taniguchi, Mai Nakamura, Tatsushi Igaki
{"title":"In vivo evidence for homeostatic regulation of ribosomal protein levels in Drosophila.","authors":"Daiki Kitamura, Kiichiro Taniguchi, Mai Nakamura, Tatsushi Igaki","doi":"10.1247/csf.23088","DOIUrl":null,"url":null,"abstract":"<p><p>The ribosome is a molecular machine essential for protein synthesis, which is composed of approximately 80 different ribosomal proteins (Rps). Studies in yeast and cell culture systems have revealed that the intracellular level of Rps is finely regulated by negative feedback mechanisms or ubiquitin-proteasome system, which prevents over- or under-abundance of Rps in the cell. However, in vivo evidence for the homeostatic regulation of intracellular Rp levels has been poor. Here, using Drosophila genetics, we show that intracellular Rp levels are regulated by proteasomal degradation of excess Rps that are not incorporated into the ribosome. By establishing an EGFP-fused Rp gene system that can monitor endogenously expressed Rp levels, we found that endogenously expressed EGFP-RpS20 or -RpL5 is eliminated from the cell when RpS20 or RpL5 is exogenously expressed. Notably, the level of endogenously expressed Hsp83, a housekeeping gene, was not affected by exogenous expression of Hsp83, suggesting that the strict negative regulation of excess protein is specific for intracellular Rps. Further analyses revealed that the maintenance of cellular Rp levels is not regulated at the transcriptional level but by proteasomal degradation of excess free Rps as a protein quality control mechanism. Our observations provide not only the in vivo evidence for the homeostatic regulation of Rp levels but also a novel genetic strategy to study in vivo regulation of intracellular Rp levels and its role in tissue homeostasis via cell competition.Key words: ribosomal protein, proteasomal degradation, Drosophila.</p>","PeriodicalId":9927,"journal":{"name":"Cell structure and function","volume":" ","pages":"11-20"},"PeriodicalIF":2.0000,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11496781/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cell structure and function","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1247/csf.23088","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/1/11 0:00:00","PubModel":"Epub","JCR":"Q4","JCRName":"CELL BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The ribosome is a molecular machine essential for protein synthesis, which is composed of approximately 80 different ribosomal proteins (Rps). Studies in yeast and cell culture systems have revealed that the intracellular level of Rps is finely regulated by negative feedback mechanisms or ubiquitin-proteasome system, which prevents over- or under-abundance of Rps in the cell. However, in vivo evidence for the homeostatic regulation of intracellular Rp levels has been poor. Here, using Drosophila genetics, we show that intracellular Rp levels are regulated by proteasomal degradation of excess Rps that are not incorporated into the ribosome. By establishing an EGFP-fused Rp gene system that can monitor endogenously expressed Rp levels, we found that endogenously expressed EGFP-RpS20 or -RpL5 is eliminated from the cell when RpS20 or RpL5 is exogenously expressed. Notably, the level of endogenously expressed Hsp83, a housekeeping gene, was not affected by exogenous expression of Hsp83, suggesting that the strict negative regulation of excess protein is specific for intracellular Rps. Further analyses revealed that the maintenance of cellular Rp levels is not regulated at the transcriptional level but by proteasomal degradation of excess free Rps as a protein quality control mechanism. Our observations provide not only the in vivo evidence for the homeostatic regulation of Rp levels but also a novel genetic strategy to study in vivo regulation of intracellular Rp levels and its role in tissue homeostasis via cell competition.Key words: ribosomal protein, proteasomal degradation, Drosophila.
期刊介绍:
Cell Structure and Function is a fully peer-reviewed, fully Open Access journal. As the official English-language journal of the Japan Society for Cell Biology, it is published continuously online and biannually in print.
Cell Structure and Function publishes important, original contributions in all areas of molecular and cell biology. The journal welcomes the submission of manuscripts on research areas such as the cell nucleus, chromosomes, and gene expression; the cytoskeleton and cell motility; cell adhesion and the extracellular matrix; cell growth, differentiation and death; signal transduction; the protein life cycle; membrane traffic; and organelles.