Project description:In this study, we show that in addition to regulating DP thymocytes survival, RORgT also controls genes that regulate thymocyte migration, proliferation, and T cell receptor (TCR) selection. Strikingly, pharmacological inhibition of RORg skews TCR gene rearrangement, limits T cell repertoire diversity, and inhibits development of autoimmune encephalomyelitis. Thus, targeting RORgT not only inhibits Th17 cell development and function but also fundamentally alters thymic-emigrant recognition of self and foreign antigens.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192. RNA content was extracted following immunoprecipitation of HuR using a monoclonal antibody (3A2) and the levels of mRNA were compared to an IgG control in order to determine which transcripts were enriched in the HuR ribonucleoprotein complex.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192. RNA content was extracted following immunoprecipitation of HuR using a monoclonal antibody (3A2) and the levels of mRNA were compared to an IgG control in order to determine which transcripts were enriched in the HuR ribonucleoprotein complex.
Project description:The progressive development of T-cells in the thymus is a highly regulated process that aims to arm the body with T-cells against pathogens whilst maintaining tolerance to self. Although the role of gene transcription in this process has been extensively studied, little is known about the significance of associated post-transcriptional mechanisms. Post-transcriptional control is imposed by the dynamic interactions of RNA-binding proteins (RBPs) with RNA molecules which destine mRNA molecules towards translation or destruction. In this study we focus on the functions of an RBP called HuR. We made use of novel transgenic systems in which HuR is deleted in thymic T-cells to test whether HuR is involved in their developmental maturation. We show that HuR controls the generation and provision of T-cells competent for the proper recognition of antigens in the body and the elimination of harmfull cells. We further show that HuR controls T-cell development through its involvement in basic cellular processes like cell cycle regulation, cellular activation, death and migration which were associated to HuR’s efficacy in regulating the expression or function of key signaling components. Our studies provide important insight on the post-transcriptional regulation of fundamental cellular processes and identify HuR as an important modulator of adaptive immunity and autoimmunity.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192.
Project description:β -selection imposes a considerable demand for new protein synthesis of the newly rearranged Tcrβ gene and the multiple factors that execute the transcriptional and metabolic programs demanded by DN thymocyte proliferation. However, how proteome homeostasis or “proteostasis” is regulated during thymocyte development is largely unknown. Here, we show that the endoplasmic reticulum (ER)- associated degradation (ERAD), but not the unfolded protein response (UPR), is the master regulator of physiological ER proteostasis in immature DN thymocytes. The ERAD machinery was critically required for successful β-selection of DN3 thymocytes and consequently, ERAD deficiency impeded αβ T cell development. The Sel1L-Hrd1 complex is the most conserved branch of mammalian ERAD machinery. Deletion of Sel1l impaired DN3 to DN4 thymocyte transition and severely impaired αβ T cell development. Mechanistically, Sel1l deficiency induced unresolved ER stress that triggered thymocyte apoptosis through the PERK pathway. This study revealed the stringent protein quality control through the SEL1L-ERAD pathway is required for successful b-selection and the development of the ab T cells that mediate adaptive immunity.