Project description:To investigate the function of Ptpn2, IFNγ and cGAS on axon regeneration, we performed gene transcription profiling of dorsal root ganglion neurons from 5 groups (WT, cKO, WT injured, cKO injured, RU521 injured) and retinal ganglion cells from 4 groups (WT, IFNγ, cKO, IFNγ+cKO).
Project description:Current treatments for neurodegenerative diseases and neural injuries fall short of success. One primary reason is that neurons in the mammalian central nervous system (CNS) lose their regeneration ability as they mature. Here, we investigated the role of Ezh2, a histone methyltransferase, in regulation of mammalian axon regeneration. We found that Ezh2 declined in the mouse nervous system during maturation but was upregulated in adult dorsal root ganglion neurons to support spontaneous axon regeneration following peripheral nerve injury. In addition, overexpression of Ezh2 in retinal ganglion cells in the CNS promoted optic nerve regeneration via both histone methylation-dependent and -independent mechanisms. Further investigation revealed that Ezh2 supported axon regeneration by systematically silencing the transcription of genes regulating synaptic function and inhibiting axon regeneration, while simultaneously activating various axon regeneration promoting factors. In particular, our study demonstrated that the GABA transporter 2 encoded by the gene Slc6a13 acted downstream of Ezh2 to control axon regeneration. Our study suggested that modulating chromatin accessibility was a promising strategy to promote CNS axon regeneration.
Project description:Injured peripheral neurons successfully activate a pro-regenerative transcriptional program to enable axon regeneration and functional recovery. How transcriptional regulators coordinate the expression of such programs remains unclear. Here we show that hypoxia-inducible factor 1α (HIF-1α) controls multiple injury-induced genes in sensory neurons and contribute to the pre-conditioning lesion effect. Knockdown of HIF-1α in vitro or conditional knockout in vivo impairs sensory axon regeneration. The HIF-1α target gene Vascular Endothelial Growth Factor A (VEGFA) is expressed in injured neurons and contributes to stimulate axon regeneration. Induction of HIF-1α using hypoxia enhances axon regeneration in vitro and in vivo in sensory neurons. Hypoxia also stimulates motor neuron regeneration and accelerates neuromuscular junction reinnervation. This study demonstrates that HIF-1α represents a critical transcriptional regulator in regenerating neurons and suggests hypoxia as a tool to stimulate axon regeneration.
Project description:Current treatments for neurodegenerative diseases and neural injuries fall short of success. One primary reason is that neurons in the mammalian central nervous system (CNS) lose their regeneration ability as they mature. Here, we investigated the role of Ezh2, a histone methyltransferase, in regulation of mammalian axon regeneration. We found that Ezh2 declined in the mouse nervous system during maturation but was upregulated in adult dorsal root ganglion neurons to support spontaneous axon regeneration following peripheral nerve injury. In addition, overexpression of Ezh2 in retinal ganglion cells in the CNS promoted optic nerve regeneration via both histone methylation-dependent and -independent mechanisms. Further investigation revealed that Ezh2 supported axon regeneration by systematically silencing the transcription of genes regulating synaptic function and inhibiting axon regeneration, while simultaneously activating various axon regeneration promoting factors. In particular, our study demonstrated that the GABA transporter 2 encoded by the gene Slc6a13 acted downstream of Ezh2 to control axon regeneration. Our study suggested that modulating chromatin accessibility was a promising strategy to promote CNS axon regeneration.
Project description:A formidable challenge in neural repair in the adult central nervous system (CNS) is the long distances that regenerating axons often need to travel in order to reconnect with their targets. Thus, a sustained capacity for axon regeneration is critical for achieving functional restoration. Although deletion of either Phosphatase and tensin homolog (PTEN), a negative regulator of mammalian target of rapamycin (mTOR), or suppressor of cytokine signaling 3 (SOCS3), a negative regulator of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, in adult retinal ganglion cells (RGCs) individually promoted significant optic nerve regeneration, such regrowth tapered off around two weeks after the crush injury. Remarkably, we now find that simultaneous deletion of both PTEN and SOCS3 enable robust and sustained axon regeneration. We further show that PTEN and SOCS3 regulate two independent pathways that act synergistically to promote enhanced axon regeneration. Gene expression analyses suggest that double deletion not only result in the induction of many growth-related genes, but also allow RGCs to maintain the expression of a repertoire of genes at the physiological level after injury. Our results reveal concurrent activation of mTOR and STAT3 pathways as a key for sustaining long-distance axon regeneration in adult CNS, a crucial step toward functional recovery. RNAs were extracted from FACS sorted YFP positive mouse retinal cells, and gene-profiled using affymetrix 1.0 ST expression arrays. Three hybridizations were performed for each group (Wild type after crush, PTEN Knockout+crush, SOCS3 Knockout+crush, and PTEN/SOCS3 double knockout+crush) with RNA samples collected from three independent FACS purifications. Data were analyzed using dChIP and SAM.
Project description:Background & aims: Loss-of-function variants in the PTPN2 gene are associated with increased risk of inflammatory bowel disease. We recently showed that Ptpn2 is critical for intestinal epithelial cell (IEC) barrier maintenance, IEC-macrophage communication, and modulation of the gut microbiome in mice, restricting expansion of a small intestinal pathobiont associated with inflammatory bowel disease. Here, we aimed to identify how Ptpn2 loss affects ileal IEC subtypes and their function in vivo. Methods: Constitutive Ptpn2 wild-type, heterozygous, and knockout (KO) mice, as well as mice with inducible deletion of Ptpn2 in IECs, were used in the study. Investigation was performed using imaging techniques, flow cytometry, enteroid culture, and analysis of gene and protein levels of IEC markers. Results: Partial transcriptome analysis showed that expression of Paneth cell-associated antimicrobial peptides Lyz1, Pla2g2a, and Defa6 was down-regulated markedly in Ptpn2-KO mice compared with wild-type and heterozygous. In parallel, Paneth cell numbers were reduced, their endoplasmic reticulum architecture was disrupted, and the endoplasmic reticulum stress protein, C/EBP-homologous protein (CHOP), was increased in Ptpn2-KO mice. Despite reduced Paneth cell number, flow cytometry showed increased expression of the Paneth cell-stimulatory cytokines interleukin 22 and interferon γ+ in CD4+ T cells isolated from Ptpn2-KO ileum. Key findings in constitutive Ptpn2-KO mice were confirmed in epithelium-specific Ptpn2ΔIEC mice, which also showed impaired lysozyme protein levels in Paneth cells compared with Ptpn2fl/fl control mice. Conclusions: Constitutive Ptpn2 deficiency affects Paneth cell viability and compromises Paneth cell-specific antimicrobial peptide production. The observed effects may contribute to the increased susceptibility to intestinal infection and dysbiosis in these mice.
Project description:Current treatments for neurodegenerative diseases and neural injuries fall short of success. One primary reason is that neurons in the mammalian central nervous system (CNS) lose their regeneration ability as they mature. Here, we investigated the role of Ezh2, a histone methyltransferase, in regulation of mammalian axon regeneration. We found that Ezh2 declined in the mouse nervous system during maturation but was upregulated in adult dorsal root ganglion neurons to support spontaneous axon regeneration following peripheral nerve injury. In addition, overexpression of Ezh2 in retinal ganglion cells in the CNS promoted optic nerve regeneration via both histone methylation-dependent and -independent mechanisms. Further investigation revealed that Ezh2 supported axon regeneration by systematically silencing the transcription of genes regulating synaptic function and inhibiting axon regeneration, while simultaneously activating various axon regeneration promoting factors. In particular, our study demonstrated that the GABA transporter 2 encoded by the gene Slc6a13 acted downstream of Ezh2 to control axon regeneration. Our study suggested that modulating chromatin accessibility was a promising strategy to promote CNS axon regeneration.
Project description:Current treatments for neurodegenerative diseases and neural injuries fall short of success. One primary reason is that neurons in the mammalian central nervous system (CNS) lose their regeneration ability as they mature. Here, we investigated the role of Ezh2, a histone methyltransferase, in regulation of mammalian axon regeneration. We found that Ezh2 declined in the mouse nervous system during maturation but was upregulated in adult dorsal root ganglion neurons to support spontaneous axon regeneration following peripheral nerve injury. In addition, overexpression of Ezh2 in retinal ganglion cells in the CNS promoted optic nerve regeneration via both histone methylation-dependent and -independent mechanisms. Further investigation revealed that Ezh2 supported axon regeneration by systematically silencing the transcription of genes regulating synaptic function and inhibiting axon regeneration, while simultaneously activating various axon regeneration promoting factors. In particular, our study demonstrated that the GABA transporter 2 encoded by the gene Slc6a13 acted downstream of Ezh2 to control axon regeneration. Our study suggested that modulating chromatin accessibility was a promising strategy to promote CNS axon regeneration.
Project description:Protein tyrosine phosphatase N2 (Ptpn2) is a type 1 diabetes (T1D) candidate gene identified from human genome-wide association studies. PTPN2 is highly expressed in human and murine islets and becomes elevated upon inflammation, suggesting that PTPN2 may be important for beta cell survival in the context of T1D. To test whether PTPN2 contributed to beta cell dysfunction in an inflammatory environment, we generated a beta cell-specific deletion of Ptpn2 in mice (Ptpn2 βKO). While unstressed animals exhibit normal metabolic profiles, streptozotocin (STZ) Ptpn2 βKO mice display marked increase in hyperglycemia and death due to exacerbated beta cell loss. Furthermore, cytokine treated Ptpn2 KO islets resulted in mitochondrial defects and reduced glucose-induced metabolic flux, suggesting beta cells lacking Ptpn2 are more susceptible to inflammatory stress associated with T1D due to compromised metabolic fitness.