Muscle denervation due to injury, disease or aging results in impaired motor function. Restoring neuromuscular communication requires axonal regrowth and regeneration of neuromuscular synapses. Muscle activity inhibits neuromuscular synapse regeneration. The mechanism by which muscle activity regulates regeneration of synapses is poorly understood. Dach2 and Hdac9 are activity-regulated transcriptional co-repressors that are highly expressed in innervated muscle and suppressed following muscle denervation. Here, we report that Dach2 and Hdac9 inhibit regeneration of neuromuscular synapses. Importantly, we identified Myog and Gdf5 as muscle-specific Dach2/Hdac9-regulated genes that stimulate neuromuscular regeneration in denervated muscle. Interestingly, Gdf5 also stimulates presynaptic differentiation and inhibits branching of regenerating neurons. Finally, we found that Dach2 and Hdac9 suppress miR206 expression, a microRNA involved in enhancing neuromuscular regeneration. Overall design: RNAseq on innervated and 3 day denervated adult soleus muscle from wildtype mice is compared with that from 3 day denervated soleus muscle from Dach2/Hdac9 deleted mice to identify Dach2/Hdac9-regulated genes.
Dach2-Hdac9 signaling regulates reinnervation of muscle endplates.
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The sensation of hunger after a period of fasting and the sensation of satiety after eating is crucial to behavioral regulation of food intake, but the biological mechanisms regulating these sensations are incompletely understood. We studied the behavioral and physiological adaptation to fasting in the vinegar fly (Drosophila melanogaster). Here we show that flies demonstrated increased behavioral attraction to food odor when food-deprived with no corresponding increase in sensitivity in the peripheral olfactory system. Flies increased their food intake transiently in the post-fasted state, but returned to a stable baseline feeding level within 24 hr after return to food. This modulation in feeding was accompanied by a significant increase in the size of the crop organ of the digestive system, suggesting that fasted flies responded both by increasing their food intake and storing reserve food in their crop. The post-fasting feeding response was observed in both male and female flies of diverse genetic backgrounds. Expression profiling of head, body, and chemosensory tissues by microarray analysis revealed several hundred genes that are regulated by feeding state, including 247 genes in the fly head. We performed RNA interference-mediated knockdown of, takeout, one of the genes strongly downregulated by fasting in multiple tissues. When takeout was knocked down in all neurons the post-fasting feeding response was abolished. These observations suggest that a coordinated transcriptional response to internal physiological state may regulate both ingestive behaviors and chemosensory perception of food
Post-fasting olfactory, transcriptional, and feeding responses in Drosophila.
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Background: Degenerative disc disease (DDD) is a primary contributor to low back pain, a leading cause of disability. Progression of DDD is aided by inflammatory cytokines in the intervertebral disc (IVD), particularly TNF-a and IL-1ß, but current treatments fail to effectively target this mechanism. The objective of this study was to explore the feasibility of CRISPR epigenome editing based therapy for DDD, by modulation of TNFR1/IL1R1 signaling in pathological human IVD cells. Methods: Human IVD cells from the nucleus pulposus of patients receiving surgery for back pain were obtained and the regulation of TNFR1/IL1R1 signaling by a lentiviral CRISPR epigenome editing system was tested. These cells were tested for successful lentiviral transduction/expression of dCas9-KRAB system and regulation of TNFR1/IL1R1 expression. TNFR1/IL1R1 signaling disruption was investigated via measurement of NF-?B activity, apoptosis, and anabolic/catabolic changes in gene expression post inflammatory challenge. Results: CRISPR epigenome editing systems were effectively introduced into pathological human IVD cells and significantly downregulated TNFR1 and IL1R1. This downregulation significantly attenuated deleterious TNFR1 signaling but not IL1R1 signaling. This is attributed to less robust IL1R1 expression downregulation, and IL-1ß driven reversal of IL1R1 expression downregulation in a portion of patient IVD cells. Additionally, RNAseq data indicated a novel transcription factor targets, IRF1 and TFAP2C, as being a primary regulators of inflammatory signaling in IVD cells. Discussion: These results demonstrate the feasibility of CRISPR epigenome editing of inflammatory receptors in pathological IVD cells, but highlight a limitation in epigenome targeting of IL1R1. This method has potential application as a novel gene therapy for DDD, to attenuate the deleterious effect of inflammatory cytokines present in the degenerative IVD. Overall design: Patient nucleus pulposus cells (TNFR1kd and nontargeting control) were analyzed by RNA-seq with and without TNF-a treatment.
Lentiviral CRISPR Epigenome Editing of Inflammatory Receptors as a Gene Therapy Strategy for Disc Degeneration.
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African American men are disproportionately affected by both vitamin D deficiency and increased risk of prostate cancer.
Prostatic compensation of the vitamin D axis in African American men.
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The heat shock response (HSR) is a mechanism to cope with proteotoxic stress by inducing the expression of molecular chaperones and other heat shock response genes. The HSR is evolutionarily well conserved and has been widely studied in bacteria, cell lines and lower eukaryotic model organisms. However, mechanistic insights into the HSR in higher eukaryotes, in particular in mammals, are limited. We have developed an in vivo heat shock protocol to analyze the HSR in mice and dissected heat shock factor 1 (HSF1)-dependent and -independent pathways. Whilst the induction of proteostasis-related genes was dependent on HSF1, the regulation of circadian function related genes, indicating that the circadian clock oscillators have been reset, was independent of its presence. Furthermore, we demonstrate that the in vivo HSR is impaired in mouse models of Huntington's disease but we were unable to corroborate the general repression of transcription after a heat shock found in lower eukaryotes. Overall design: RNA-Seq was performed on mRNA isolated from quadriceps femoris muscle of 24 mice. These mice were of wild type, R6/2, and Hsf1-/- genotypes. Two mice of each genotype were tested in four conditions: (1) heat shock, (2) control heat shock, (3) HSP90 inhibition (NVP-HSP990), and (4) HSP90 inhibition vehicle.
HSF1-dependent and -independent regulation of the mammalian in vivo heat shock response and its impairment in Huntington's disease mouse models.
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The goal of this study was to assess whether the presence of HLA-B*35 contributes to activation of ER stress/UPR and inflammation in lcSScPAH PBMC.
The HLA-B*35 allele modulates ER stress, inflammation and proliferation in PBMCs from Limited Cutaneous Systemic Sclerosis patients.
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The coupling between cell-cycle exit and onset of differentiation is a common feature throughout the developing nervous system, but the mechanisms that link these processes are mostly unknown. Although the transcription factor Pax6 was implicated in both proliferation and differentiation of multiple regions within the CNS, its contribution to the transition between these successive states remains elusive. To gain insight into the role of Pax6 during the transition from proliferating progenitors to differentiating precursors, we investigated cell-cycle and transcriptomic changes occurring in Pax6- retinal progenitor cells (RPCs). Our analyses revealed a unique cell-cycle phenotype of the Pax6-deficient RPCs, which included a reduced number of cells in the S phase, an increased number of cells exiting the cell cycle, and delayed differentiation kinetics of Pax6- precursors. These alterations were accompanied by co-expression of factors that promote (Ccnd1, Ccnd2, Ccnd3) and inhibit (P27kip1 and P27kip2) the cell cycle. Further characterization of the changes in transcription profile of the Pax6-deficient RPCs revealed abrogated expression of multiple factors which are known to be involved in regulating proliferation of RPCs, including the transcription factors Vsx2, Nr2e1, Plagl1 and Hedgehog signaling. These findings provide novel insight into the molecular mechanism mediating the pleiotropic activity of Pax6 in RPCs. The results further suggest that rather than conveying a linear effect on RPCs, such as promoting their proliferation and inhibiting their differentiation, Pax6 regulates multiple transcriptional networks which function simultaneously, thereby conferring the capacity to proliferate, assume multiple cell fates and execute the differentiation program into retinal lineages.
Pax6 is required for normal cell-cycle exit and the differentiation kinetics of retinal progenitor cells.
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Astrocyte-secreted proteins induce synapse formation between isolated retinal ganglion cell (RGC) neurons in culture. We asked whether 2 of these proteins, glypican 4 (Gpc4) or thrombospondin 1 (TSP1) induce synapse formation by regulating gene expression in RGCs.
Astrocyte-Secreted Glypican 4 Regulates Release of Neuronal Pentraxin 1 from Axons to Induce Functional Synapse Formation.
Although the induction of C-FOS in the brain has been extensively studied for several decades to date there has been no attempt to identify the targets of C-FOS at a genome wide level, and it was not known how many genes C-FOS activates in a given cell. To identify potential C-FOS target genes, we performed microarray analysis on RNA obtained from mouse cortical (mCTX) neurons infected with lentivirus containing either a control shRNA (targeting firefly luciferase) or c-Fos shRNA that were subsequently depolarized with 0, 1, 3, or 6 hours of KCl.
Genome-wide identification and characterization of functional neuronal activity-dependent enhancers.
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Expansion of beta cells from the limited number of adult human islet donors is an attractive prospect for increasing cell availability for cell therapy of diabetes. However, while evidence supports the replicative capacity of adult beta cells in vivo, attempts at expanding human islet cells in tissue culture resulted in loss of beta-cell phenotype. Using a genetic lineage-tracing approach we have provided evidence for massive proliferation of beta-cell-derived (BCD) cells within these cultures. Expansion involves dedifferentiation resembling epithelial-mesenchymal transition (EMT). Epigenetic analyses indicate that key beta-cell genes maintain a partially open chromatin structure in expanded BCD cells, although they are not transcribed. Here we report that BCD cells can be induced to redifferentiate by a combination of soluble factors. The redifferentiated cells express beta-cell genes, store insulin in typical secretory vesicles, and release it in response to glucose. The redifferentiation process involves mesenchymal-epithelial transition, as judged from changes in gene expression. Moreover, inhibition of the EMT effector SLUG using shRNA results in stimulation of redifferentiation. BCD cells also give rise at a low rate to cells expressing other islet hormones, suggesting transition through an islet progenitor-like stage during redifferentiation. These findings suggest that ex-vivo expansion of adult human islet cells is a promising approach for generation of insulin-producing cells for transplantation, as well as basic research, toxicology studies, and drug screening.
Insulin-producing cells generated from dedifferentiated human pancreatic beta cells expanded in vitro.
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