Huntingtons Disease (HD) is an inherited neurodegenerative disease caused by a glutamine repeat expansion in huntingtin protein. Transcriptional deregulation and altered energy metabolism have been implicated in HD pathogenesis. We report here that mutant huntingtin causes disruption of mitochondrial function by inhibiting expression of PGC-1a, a transcriptional coactivator that regulates several metabolic processes including mitochondrial biogenesis and respiration. Mutant huntingtin represses PGC-1a gene transcription by associating with the promoter and interfering with the CREB/TAF4-dependent transcriptional pathway critical for the regulation of PGC-1a gene expression. Crossbreeding of PGC-1a knockout mice with HD knock-in mice leads to increased neurodegeneration of striatal neurons and motor abnormalities in the HD mice. Importantly, expression of PGC-1a partially reverses the toxic effects of mutant huntingtin in cultured striatal neurons. Moreover, lentiviral-mediated delivery of PGC-1a in the striatum provides neuroprotection in the transgenic HD mice. These studies suggest a key role for PGC-1a in the control of energy metabolism in the early stages of HD pathogenesis.
Transcriptional repression of PGC-1alpha by mutant huntingtin leads to mitochondrial dysfunction and neurodegeneration.
Sex, Age, Specimen part
View SamplesThe Spt4-Spt5 complex, and its human homolog DSIF (DRB sensitivity-inducing factor), is unique in its ability to regulate Pol II processivity. Previous studies have shown that Spt5 has the characteristics of a general transcription-elongation factor. However, mutagenesis of Spt5 showed specific phenotypes during development, which were far less severe than those of Pol II defects or TBP deficient embryos. It seems paradoxical that a mutation which alters a general elongation factor can cause rather specific developmental defects. By using Spt5 knockdown zebrafish embryos and microarrays, here we showed that transcript abundance for only a small subset of genes is altered by loss of Spt5. Further investigation of the down-regulated genes showed that the genes most intensely repressed by the knockdown were strongly activated during early development in untreated embryos. Thus, this study shows that gene activation levels may create different requirements for Pol II processivity. Active transcription requires Spt5 for efficient elongation through its stimulatory activity on Pol II processivity.
Erythropoiesis is regulated by the transcription elongation factor Foggy/Spt5 through gata1 gene regulation.
Age
View SamplesHere we harnessed the potential of RNA sequencing in 89 human pancreatic islet donors to identify genes and exons regulated in this relevant tissue for T2D. Overall design: mRNA profiles of 89 human pancreatic islet donors having different levels of blood glucose (HbA1c) with and without T2D. The data was generated by deep sequencing using Illumina HiSeq 2000.
Orphan G-protein coupled receptor 183 (GPR183) potentiates insulin secretion and prevents glucotoxicity-induced β-cell dysfunction.
Sex, Age, Specimen part, Subject
View SamplesExpression profiling of cell cycle genes in human pancreatic islets with and without type 2 diabetes
Autoimmunity against INS-IGF2 protein expressed in human pancreatic islets.
Sex, Age, Specimen part
View SamplesThe aim of this study was to investigate correlations between early subclinical findings (10 and 90 day histology and gene expression data) and late outcomes (transplant glomerulopathy and graft loss) in positive crossmatch kidney transplants (+XMKTx).
Unique molecular changes in kidney allografts after simultaneous liver-kidney compared with solitary kidney transplantation.
Specimen part, Subject
View SamplesA gene co-expression network analysis has been conducted to identify T2D-associated gene modules. Donors 1-48 were used for the initial analysis and donors 49-80 for the replication and were normalized separately in this study
Secreted frizzled-related protein 4 reduces insulin secretion and is overexpressed in type 2 diabetes.
Sex, Age, Specimen part
View SamplesWe screened for differentially expressed genes in the developing notochord using the Affymetrix microarray system in Xenopus laevis. At late gastrula, we dissected four regions from the embryo, anterior mesoderm, posterior mesoderm, notochord and presomitic mesoderm. Three types of comparison were carried out to generate a list of predominantly notochord expressed genes: (1) Posterior mesoderm vs. anterior mesoderm; notochord genes are expected to be increased since the notochord is located in the posterior mesoderm. (2) Posterior mesoderm vs. whole embryos; notochord genes are expected to be increased. (3) Notochord vs. somite. This comparison sub-divided the group of posterior mesodermal genes identified in (1) and (2). All tissues are dissected using tungsten needles. We first dissected dorsal tissue above the archenteron from late gastrula to early neurula. To loosen tissue, we treated the dissected dorsal explant in a 1% cysteine solution (pH 7.4) and removed the neuroectodermal layer. Anterior mesoderm was dissected corresponding to about the anterior one-third of the archenteron roof, and the rest was collected as posterior mesoderm. The posterior mesodermal explant was dissected into notochord and somites, following a clearly visible border between the two tissues. The accuracy of all dissection was confirmed by RT-PCR of marker genes.
Coordinated activation of the secretory pathway during notochord formation in the Xenopus embryo.
Specimen part
View SamplesStudies on the early embryonic development of Xenopus laevis contributed much to the understanding of vertebrate patterning. Gastrula stages are of particular interest because establishment of the axis and germ layer formation take place during these stages. While many genes belonging to several signaling pathways including FGF, Wnt and TGF-beta, have been implicated in patterning the gastrula embryo, the hierarchical interactions between these factors are incompletely known. To study this question, we took advantage of microarray technology to create a regional gene expression profile for the Xenopus gastrula.
Coordinated activation of the secretory pathway during notochord formation in the Xenopus embryo.
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View SamplesGenome wide gene expression analysis in G9a knockdown myoblasts
G9a promotes proliferation and inhibits cell cycle exit during myogenic differentiation.
Specimen part
View SamplesFibroadenomas are the most common benign breast tumors in women under 30. Unlike their malignant counterparts, relatively molecular profiling has been done on fibroadenomas. Here we performed gene expression profiling on ten fibroadenomas in order to better characterize these tumors. Through targeted amplicon sequencing, we have found that six of these tumors have MED12 mutations. We show that the MED12 mutations, among others, are associated with activated estrogen signaling, as well as increased invasiveness through upregulation of ECM remodelling genes.
Exome sequencing identifies highly recurrent MED12 somatic mutations in breast fibroadenoma.
Age
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