Cocaine-mediated repression of the histone methyltransferase (HMT) G9a has recently been implicated in transcriptional, morphological, and behavioral responses to chronic cocaine administration. Here, using a ribosomal affinity purification approach, we find that G9a repression by cocaine occurs in both Drd1 (striatonigral)- and Drd2 (striatopallidal)-expressing medium spiny neurons (MSNs). Conditional knockout and overexpression of G9a within these distinct cell types, however, reveals divergent behavioral phenotypes in response to repeated cocaine treatment. Our studies further indicate that such developmental deletion of G9a selectively in Drd2 neurons results in the unsilencing of transcriptional programs normally specific to striatonigral neurons, and the acquisition of Drd1-associated projection and electrophysiological properties. This partial striatopallidal to striatonigral switching phenotype in mice indicates a novel role for G9a in contributing to neuronal subtype identity, and suggests a critical function for cell-type specific histone methylation patterns in the regulation of behavioral responses to environmental stimuli.
G9a influences neuronal subtype specification in striatum.
Sex, Specimen part
View SamplesEfferent inhibition of cochlear outer hair cells is mediated by nicotinic cholinergic receptors containing alpha9 (a9) and alpha10 subunits. Mice lacking a9 nicotinic subunits fail to exhibit classic olivocochlear responses and are characterized by abnormal synaptic morphology at the base of outer hair cells. To detail molecular changes induced upon the loss of a9 subunit, we sampled cochlear RNA from wild type and a9 null mice at postnatal (P) days spanning periods of synapse formation and maturation (P3, P7, P13 and P60). Our findings point to a delay in cochlear maturation starting at the onset of hearing (P13), as well as an up-regulation of various GABA receptor subunits in adult mice lacking the a9 nicotinic subunit.
Lack of nAChR activity depresses cochlear maturation and up-regulates GABA system components: temporal profiling of gene expression in alpha9 null mice.
Specimen part
View SamplesVaccinia virus infection of mouse lungs produces a focal infection within the lung remaining at the large bronchi throughout the course of infection. Animals die of respiratory failure with little edema and few infiltrating immune cells. It is well established that poxviruses control the host immune system by encoding multiple host defense pathway antagonists.
Roles of vaccinia virus genes E3L and K3L and host genes PKR and RNase L during intratracheal infection of C57BL/6 mice.
Specimen part
View SamplesHistone deacetylases (Hdac) remove acetyl groups from proteins, influencing global and specific gene expression. Hdacs control inflammation, as shown by Hdac inhibitor-dependent protection from DSS-induced murine colitis. While tissue-specific Hdac knockouts show redundant and specific functions, little is known of their intestinal epithelial cell (IEC) role. We have shown previously that dual Hdac1/Hdac2 IEC-specific loss disrupts cell proliferation and determination, with decreased secretory cell numbers and altered barrier function. We thus investigated how compound Hdac1/Hdac2 or Hdac2 IEC-specific deficiency alters the inflammatory response. Floxed Hdac1 and Hdac2 and villin-Cre mice were interbred. Compound Hdac1/Hdac2 IEC-deficient mice showed chronic basal inflammation, with increased basal Disease Activity Index (DAI) and deregulated Reg gene colonic expression. DSS-treated dual Hdac1/Hdac2 IEC-deficient mice displayed increased DAI, histological score, intestinal permeability and inflammatory gene expression. In contrast to double knockouts, Hdac2 IEC-specific loss did not affect IEC determination and growth, nor result in chronic inflammation. However, Hdac2 disruption protected against DSS colitis, as shown by decreased DAI, intestinal permeability and caspase-3 cleavage. Hdac2 IEC-specific deficient mice displayed increased expression of IEC gene subsets, such as colonic antimicrobial Reg3b and Reg3g mRNAs, and decreased expression of immune cell function-related genes. Our data show that Hdac1 and Hdac2 are essential IEC homeostasis regulators. IEC-specific Hdac1 and Hdac2 may act as epigenetic sensors and transmitters of environmental cues and regulate IEC-mediated mucosal homeostatic and inflammatory responses. Different levels of IEC Hdac activity may lead to positive or negative outcomes on intestinal homeostasis during inflammation
The acetylome regulators Hdac1 and Hdac2 differently modulate intestinal epithelial cell dependent homeostatic responses in experimental colitis.
Specimen part
View SamplesBiliary atresia (BA) is a rare cholestatic disease of unknown etiology that affects infants and shows an incidence of 1 out of 18,000 live births in Europe (1). The first therapeutic option is a timely performed portoenterostomy. However, the majority of patients suffer from a progressive inflammatory process, which leads to complete destruction of the extra- and intrahepatic biliary system followed by end-stage liver cirrhosis. Hence, BA is the leading indication for pediatric liver transplantation worldwide (2, 3). To understand the pathogenesis of the disease and improve theoutcome of BA patients, research has focused on the inflammatory process in liver and bile ducts, in which several factors are remarkably elevated, such as activated CD4 and CD8 T-cells, TNF alpha,IFN alpha and other proinflammatory TH1 cytokines (3-8). By the time of diagnosis, however, the disease has already reached an advanced state, characterized by the complete obstruction of the extrahepatic bile ducts with impaired bile flow and fibrosis or cirrhosis of the liver. Therefore, studies in humans focusing on the trigger mechanism of BA are limited due to the paucity of liver and availability of bile duct tissue for research. One infectious animal model has been developed, in which newborn Balb/c mice exclusively show the experimental BA phenotype after infection with rhesus rotavirus (RRV) (9, 10). This model allows the analysis of the inflammatory reactions in liver and bile ducts at early steps in the development of bile duct atresia (11-20). Furthermore, inbred mouse strains have been shown to have a different susceptibility for the development of experimental BA, suggesting that Balb/c mice have an immunological gap responsible for disease progression (10, 12). The aim of this study was to identify key genes responsible for the BA phenotype by comparing the transcriptomes at an early time point after virus infection, i.e. before bile duct atresia, between two mouse strains with different susceptibilities to BA. Differences in the virus titration and the clinical course of infected mice were analyzed, and variations in the hepatic gene response assessed by comparative microarray assays were correlated to variances in the hepatic inflammatory reaction.
Susceptibility to experimental biliary atresia linked to different hepatic gene expression profiles in two mouse strains.
Specimen part
View SamplesThis is to compare the gene expression profile of Th1 and Th17 cells.
Late developmental plasticity in the T helper 17 lineage.
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View SamplesTo model the potential diabetogenic effects of higher level of HSD11B1 in b-cells of the pancreas in vivo, we created a transgenic model overexpressing HSD11B1 under the mouse insulin I promoter (MIP-HSD1) in diabetes-prone C57Bl/KsJ mice. KsJ wild type and MIP-HSD1 heterozygous mice have been high fat fed for 12 weeks. Pancreata have been perfused with collagenase and islets isolated by hand picking. Isolated islets (around 500) coming from at least 3 mice (around 200/mice) have been directly lysed in Trizol. Total RNA have been extracted by Trizol plus RNA Purification Kit (invitrogen).
Optimal elevation of β-cell 11β-hydroxysteroid dehydrogenase type 1 is a compensatory mechanism that prevents high-fat diet-induced β-cell failure.
Specimen part
View SamplesCD95 (also called FAS and APO-1) is a prototypical death receptor that
CD95 promotes tumour growth.
Sex, Age, Specimen part, Cell line
View SamplesThe main cell of origin of the Sonic hedgehog (SHH) subgroup of medulloblastoma (MB) is granule cell precursors (GCPs), a SHH-dependent transient amplifying population in the developing cerebellum. SHH-MBs can be further subdivided based on molecular and clinical parameters, as well as location since SHH-MBs occur preferentially in the lateral cerebellum (hemispheres). Our analysis of adult patient data suggests that tumors with Smoothened (SMO) mutations form more specifically in the hemispheres than those with Patched 1 (PTCH1) mutations. Using sporadic mouse models of SHH-MB with the two mutations commonly seen in adult MB, constitutive activation of Smo (SmoM2) or loss-of-Ptch1, we found that regardless of timing of induction or type of mutation, tumors developed primarily in the hemispheres with SmoM2-mutants indeed showing a stronger specificity. We further uncovered that GCPs in the hemispheres are more susceptible to high level SHH signaling compared to GCPs in the medial cerebellum (vermis), as more SmoM2 or Ptch1-mutant hemisphere cells remain undifferentiated and show increased tumorigenicity when transplanted. Finally, we identified location-specific GCP gene expression profiles, and found that deletion of the genes most highly expressed in the hemispheres (Nr2f2) or vermis (Engrailed1) showed opposing effects on GCP differentiation. Our studies thus provide new insights into intrinsic differences within GCPs that impact on SHH-MB progression.
Lateral cerebellum is preferentially sensitive to high sonic hedgehog signaling and medulloblastoma formation.
Specimen part
View SamplesWe assessed the impact of glucose transporter Glut2 gene inactivation in adult mouse liver (LG2KO mice). This suppressed hepatic glucose uptake but not glucose output. In the fasted state, expression of carbohydrate responsive element-binding protein (ChREBP) and its glycolytic and lipogenic target genes was abnormally elevated. Feeding, energy expenditure, and insulin sensitivity were identical in LG2KO and control mice. Glucose tolerance was normal early after Glut2 inactivation but intolerance developed at later time. This was caused by progressive impairment of glucose-stimulated insulin secretion even though beta-cell mass and insulin content remained normal. Liver transcript profiling revealed a coordinate down-regulation of cholesterol biosynthesis genes in LG2KO mice. This was associated with reduced hepatic cholesterol in fasted mice and a 30 percent reduction in bile acid production. We showed that chronic bile acids or FXR agonist treatment of primary islets increases glucose-stimulated insulin secretion, an effect not seen in islets from fxr-/- mice. Collectively, our data show that glucose sensing by the liver controls beta-cell glucose competence, through a mechanism that likely depends on bile acid production and action on beta-cells.
Hepatic glucose sensing is required to preserve β cell glucose competence.
Specimen part
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