iProXProteomicsXuejiang GuoMus Musculushttp://www.iprox.org/page/project.html?id=IPX0006233000guo_xuejiang@njmu.edu.cnNanjing Medical UniversityiProX<h4>Background</h4>Circular RNAs (circRNAs) are a large class of mammalian RNAs. Several protein products translated by circRNAs have been reported to be involved in the development of various tissues and systems; however, their physiological functions in male reproduction have yet not been explored.<h4>Results</h4>Here, we report an endogenous circRNA (circRsrc1) that encodes a novel 161-amino-acid protein which we named Rsrc1-161aa through circRNA sequencing coupled with mass spectrometry analysis on mouse testicular tissues. Deletion of Rsrc1-161aa in mice impaired male fertility with a significant decrease in sperm count and motility due to dysfunctions of mitochondrial energy metabolism. A series of in vitro rescue experiments revealed that circRsrc1 regulates mitochondrial functions via its encoded protein Rsrc1-161aa. Mechanistically, Rsrc1-161aa directly interacts with mitochondrial protein C1qbp and enhances its binding activity to mitochondrial mRNAs, thereby regulating the assembly of mitochondrial ribosomes and affecting the translation of oxidative phosphorylation (OXPHOS) proteins and mitochondrial energy metabolism.<h4>Conclusions</h4>Our studies reveal that Rsrc1-161aa protein encoded by circRsrc1 regulates mitochondrial ribosome assembly and translation during spermatogenesis, thereby affecting male fertility.A novel protein encoded by circRsrc1 regulates mitochondrial ribosome assembly and translation during spermatogenesis.Zhang Shu S, Wang Chang C, Wang Yue Y, Zhang Hao H, Xu Chen C, Cheng Yiwei Y, Yuan Yan Y, Sha Jiahao J, Guo Xuejiang X, Cui Yiqiang YfalseIdentification and quantitative proteomic analysis of a novel protein in GC-1 cell line and mouse testis.We utilized a proteomic screening strategy to discover a novel protein encoded by an endogenous circRNA and we verified the existence of this protein by protein targeting quantitative experiments both in GC-1 cell line and in mouse testis. Simultaneously，we identified its interacting proteins using IP-MS and we performed protein quantitative analysis on mitochondria-related proteins and found that the absence of this protein would affect the function of mitochondria.Sat Apr 08 00:00:00 BST 2023PXD0414241009037095490