Project description:Mesoderm development is a finely tuned process initiated by the differentiation of pluripotent epiblast cells. Serine/threonine kinase 40 (STK40) controls the development of several mesoderm-derived cell types, its overexpression induces differentiation of mouse embryonic stem cells (mESCs) towards the extraembryonic endoderm, and Stk40 knockout (KO) results in multiple organ failure and is lethal at the perinatal stage in mice. However, molecular mechanisms underlying the physiological functions of STK40 in the mesoderm differentiation remain elusive. Here, we report that Stk40 ablation impairs mesoderm differentiation both in vitro and in vivo. Mechanistically, STK40 interacts with both the E3 ubiquitin ligase mammalian constitutive photomorphogenesis protein 1 (COP1) and the transcriptional regulator proto-oncogene c-Jun (c-JUN), promoting c-JUN protein degradation. Consequently, Stk40 knockout leads to c-JUN protein accumulation, which, in turn, apparently suppresses the WNT signaling activity and impairs the mesoderm differentiation process. Overall, this study reveals that STK40, together with COP1, represents a previously unknown regulatory axis that modulates the c-JUN protein level within an appropriate range during mesoderm differentiation from mESCs. Our findings provide critical insights into the molecular mechanisms regulating the c-JUN protein level and may have potential implications for managing cellular disorders arising from c-JUN dysfunction.
Project description:Serine/threonine kinase 40 (Stk40) was previously identified as a direct target gene of pluripotency-associated transcription factor Oct4 and its overexpression could facilitate differentiation of mouse embryonic stem cells (mESCs) towards the extraembryonic endoderm. Stk40-/- mice are lethal at the perinatal stage, displaying multiple organ failures. However, the molecular mechanisms underlying the physiological functions of Stk40 remain elusive. Here, we report that Stk40 ablation compromises the mesoderm differentiation from mESCs in vitro and in embryos. Mechanistically, Stk40 interacts with both mammalian constitutive photomorphogenic protein 1 (Cop1) and c-Jun, promoting degradation of c-Jun. Consequently, Stk40 knockout leads to c-Jun protein accumulation, which, in turn, might suppress the Wnt signaling activity and impair the mesoderm differentiation process. Overall, this study reveals that Stk40, together with Cop1, represent a novel axis for modulating c-Jun protein levels within an appropriate range during mesoderm differentiation from mESCs. Our finding provides new insight into the molecular mechanism regulating c-Jun protein stability and may have potential for managing related cellular disorders.
Project description:To further dissect whether and how activated JUN reconfigures the chromatin landscape, we performed Chromatin Immunoprecipitation (ChIP)-seq analyses for H3K4me1 and H3K27ac. Based on the significant increase of H3K27ac levels at H3K4me1+ sites, we identified 3,017 JUN-activated enhancers in JUN WT cells. In contrast, JUN AA fails to significantly induce H3K27ac accumulation at these regions. Their enrichment levels at JUN-activated enhancers were significantly decreased after JNKi treatment. Besides, these enhancers are directly driven by JUN, especially phosphorylated JUN.
Project description:To examine the effects of phosphorylated JUN-mediated enhancers activation on gene expression, we conducted RNA-seq analysis in JUN wildtype (WT) or JUN inactive mutant (JUN AA) overexpressed MRC5 cells. The expression levels of genes associated with JUN-activated enhancers are significantly upregulated in JUN WT cells rather than in JUN AA cells. To quantify the effects of JUN inactivation on gene expression, we also performed RNA-seq analysis in JNKi-treated induced CAFs (iCAFs). We observed that JNKi significantly reduced expression levels of JUN-activated enhancers-associated genes.
Project description:To determine target genes, biological functions of Jun and mechanisms of gene regulation by Jun in regenerating neurons, gene expression profiling was carried out of axotomized and uninjured facial motor neurons in floxed c-Jun mice crossed with nestin-cre mice. Nestin-promoter-driven Cre ensures deletion of Jun in the central nervous system including facial motor neurons. KO animals were Jun Flox/Fox Cre+, while WT animals were Jun Flox/Flox, Cre-.
Project description:After nerve injury, myelin and Remak Schwann cells reprogram to repair cells specialized for regeneration. Normally providing strong regenerative support, these cells fail in aging animals, and during the chronic denervation that results from slow axon growth. This impairs axonal regeneration and causes a significant clinical problem. We find that aging and chronically denervated repair cells express reduced c-Jun protein and the regenerative support provided by these cells is also reduced. In both cases, genetically restoring Schwann cell c-Jun levels restores regeneration to that in controls. We identify potential gene candidates mediating this effect and implicate Shh in the control of Schwann cell c-Jun levels. These experiments reveal that a common mechanism, reduced c-Jun in repair cells, underlies two major reasons for regeneration failure in the PNS. They underscore the central importance of Schwann cell c-Jun as a regulator of nerve repair, and point to molecular pathways that can be manipulated for improving the clinical outcome of nerve injuries.
Project description:This SuperSeries is composed of the following subset Series: GSE39928: Murine livers post DEN treatment: c-Jun f/f vs. c-Jun Dli [35MM] GSE39929: Murine livers post DEN treatment: c-Jun f/f vs. c-Jun Dli [40MM] GSE39930: Murine livers post DEN treatment: c-Jun f/f vs. c-Jun Dli [41MM] GSE39931: Murine livers post DEN treatment: c-Jun f/f vs. c-Jun Dli [43MM] Refer to individual Series ** Six samples in each Series represent the same set of biological source material hybridized to 4 different arrays (named IMP internal: 35MM, 40MM, 41MM, and 43MM).