title: Downregulation of cold-inducible RNA-binding protein activates mitogen-activated protein kinases and impairs spermatogenic function in mouse testes.
abstract: Cold-inducible RNA-binding protein (CIRP) is an RNA-binding protein that is expressed in normal testes and downregulated after heat stress caused by cryptorchidism, varicocele or environmental temperatures. The purpose of this study was to investigate the functions of CIRP in the testes. We employed RNAi technique to knock down the expression of CIRP in the testes, and performed haematoxylin and eosin staining to evaluate morphological changes following knockdown. Germ cell apoptosis was examined by terminal deoxynucleotidal transferase-mediated dUTP nick end labelling (TUNEL) assay, and mitogen-activated protein kinase (MAPK) signalling pathways were investigated by Western blotting to determine the possible mechanism of apoptosis. We found that using siRNA is a feasible and reliable method for knocking down gene expression in the testes. Compared to controls, the mean seminiferous tubule diameter (MSTD) and the thickness of the germ cell layers decreased following siRNA treatment, whereas the percentage of apoptotic seminiferous tubules increased. The p44/p42, p38 and SAPK/JNK MAPK pathways were activated after downregulation of CIRP. In conclusion, we discovered that downregulation of CIRP resulted in increased germ cell apoptosis, possibly via the activation of the p44/p42, p38 and SAPK/JNK MAPK pathways.
authors.affiliation: Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Xia
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Zheng
authors.forename: Hang
authors.initials: H
authors.lastname: Zheng
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Liu
authors.forename: Gui-Yong
authors.initials: GY
authors.lastname: Liu
authors.forename: Xing-Huan
authors.initials: XH
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D003080:Cold Temperature; D015536:Down-Regulation; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques / Q000379:methods; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D013091:Spermatogenesis; D013737:Testis / Q000378:metabolism*
chemical_list: C106176:Cirbp protein, mouse; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases