Areas and layers of the cerebral cortex are specified by genetic programs that are initiated in progenitor cells and then, implemented in postmitotic neurons. Here, we report that Tbr1, a transcription factor expressed in postmitotic projection neurons, exerts positive and negative control over both regional (areal) and laminar identity. Tbr1 null mice exhibited profound defects of frontal cortex and layer 6 differentiation, as indicated by down-regulation of gene-expression markers such as Bcl6 and Cdh9. Conversely, genes that implement caudal cortex and layer 5 identity, such as Bhlhb5 and Fezf2, were up-regulated in Tbr1 mutants. Tbr1 implements frontal identity in part by direct promoter binding and activation of Auts2, a frontal cortex gene implicated in autism. Tbr1 regulates laminar identity in part by downstream activation or maintenance of Sox5, an important transcription factor controlling neuronal migration and corticofugal axon projections. Similar to Sox5 mutants, Tbr1 mutants exhibit ectopic axon projections to the hypothalamus and cerebral peduncle. Together, our findings show that Tbr1 coordinately regulates regional and laminar identity of postmitotic cortical neurons.
Tbr1 regulates regional and laminar identity of postmitotic neurons in developing neocortex.
Specimen part
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Mutant huntingtin's effects on striatal gene expression in mice recapitulate changes observed in human Huntington's disease brain and do not differ with mutant huntingtin length or wild-type huntingtin dosage.
No sample metadata fields
View SamplesTo test the hypotheses that mutant huntingtin protein length and wild-type huntingtin dosage have important effects on disease-related transcriptional dysfunction, we compared the changes in mRNA in seven genetic mouse models of Huntington's disease (HD) and postmortem human HD caudate. Transgenic models expressing short N-terminal fragments of mutant huntingtin (R6/1 and R6/2 mice) exhibited the most rapid effects on gene expression, consistent with previous studies. Although changes in the brains of knock-in and full-length transgenic models of HD took longer to appear, 15- and 22-month CHL2(Q150/Q150), 18-month Hdh(Q92/Q92) and 2-year-old YAC128 animals also exhibited significant HD-like mRNA signatures. Whereas it was expected that the expression of full-length huntingtin transprotein might result in unique gene expression changes compared with those caused by the expression of an N-terminal huntingtin fragment, no discernable differences between full-length and fragment models were detected. In addition, very high correlations between the signatures of mice expressing normal levels of wild-type huntingtin and mice in which the wild-type protein is absent suggest a limited effect of the wild-type protein to change basal gene expression or to influence the qualitative disease-related effect of mutant huntingtin. The combined analysis of mouse and human HD transcriptomes provides important temporal and mechanistic insights into the process by which mutant huntingtin kills striatal neurons. In addition, the discovery that several available lines of HD mice faithfully recapitulate the gene expression signature of the human disorder provides a novel aspect of validation with respect to their use in preclinical therapeutic trials.
Mutant huntingtin's effects on striatal gene expression in mice recapitulate changes observed in human Huntington's disease brain and do not differ with mutant huntingtin length or wild-type huntingtin dosage.
No sample metadata fields
View SamplesTo test the hypotheses that mutant huntingtin protein length and wild-type huntingtin dosage have important effects on disease-related transcriptional dysfunction, we compared the changes in mRNA in seven genetic mouse models of Huntington's disease (HD) and postmortem human HD caudate. Transgenic models expressing short N-terminal fragments of mutant huntingtin (R6/1 and R6/2 mice) exhibited the most rapid effects on gene expression, consistent with previous studies. Although changes in the brains of knock-in and full-length transgenic models of HD took longer to appear, 15- and 22-month CHL2(Q150/Q150), 18-month Hdh(Q92/Q92) and 2-year-old YAC128 animals also exhibited significant HD-like mRNA signatures. Whereas it was expected that the expression of full-length huntingtin transprotein might result in unique gene expression changes compared with those caused by the expression of an N-terminal huntingtin fragment, no discernable differences between full-length and fragment models were detected. In addition, very high correlations between the signatures of mice expressing normal levels of wild-type huntingtin and mice in which the wild-type protein is absent suggest a limited effect of the wild-type protein to change basal gene expression or to influence the qualitative disease-related effect of mutant huntingtin. The combined analysis of mouse and human HD transcriptomes provides important temporal and mechanistic insights into the process by which mutant huntingtin kills striatal neurons. In addition, the discovery that several available lines of HD mice faithfully recapitulate the gene expression signature of the human disorder provides a novel aspect of validation with respect to their use in preclinical therapeutic trials.
Mutant huntingtin's effects on striatal gene expression in mice recapitulate changes observed in human Huntington's disease brain and do not differ with mutant huntingtin length or wild-type huntingtin dosage.
No sample metadata fields
View SamplesAchieving a mechanistic understanding of disease and initiating preclinical therapeutic trials necessitate the study of huntingtin toxicity and its remedy in model systems. To allow the engagement of appropriate experimental paradigms, Huntingtons disease (HD) models need to be validated in terms of how they recapitulate a particular aspect of human disease. In order to examine transcriptome-related effects of mutant huntingtin, we compared striatal mRNA profiles from seven genetic mouse models of disease to that of postmortem human HD caudate using microarray analysis. Transgenic models expressing short N-terminal fragments of mutant huntingtin (R6/1 and R6/2 mice) exhibited the most rapid effects on gene expression, consistent with previous studies. Although changes in the brains of knock-in models of HD took longer to appear, 15-month and 22-month CHL2Q150/Q150, 18-month HdhQ92/Q92 and 2-year-old YAC128 animals also exhibited significant HD-like mRNA signatures. When the affected genes were compared across models, a robust concordance was observed. Importantly, changes concordant across multiple lines mice were also in excellent agreement with the mRNA changes seen in human HD caudate. Although it was expected that the expression of full-length huntingtin transprotein might result in unique gene expression changes compared to those caused by expression of an N-terminal huntingtin fragment, no discernable differences between full-length and fragment models were detected. There was, however, an overall concordance between transcriptomic signature and disease stage. We thus conclude that the transcriptional changes of HD can be modelled in several available lines of transgenic mice, comprising lines expressing both N-terminal and full-length mutant huntingtin proteins. The combined analysis of mouse and human HD transcriptomes provides an important chronology of mutant huntingtin's gene expression effects.
Mutant huntingtin's effects on striatal gene expression in mice recapitulate changes observed in human Huntington's disease brain and do not differ with mutant huntingtin length or wild-type huntingtin dosage.
Sex, Age, Specimen part
View SamplesMurine models have been valuable instruments in defining the pathogenesis of diabetic nephropathy (DN), but they only partially recapitulate disease manifestations of human DN, limiting their utility . In order to define the molecular similarities and differences between human and murine DN, we performed a cross-species comparison of glomerular transcriptional networks. Glomerular gene expression was profiled in patients with early type 2 DN and in three mouse models (streptozotocin DBA/2 mice, db/db C57BLKS, and eNOS-deficient C57BLKS db/db mice). Species-specific transcriptional networks were generated and compared with a novel network-matching algorithm. Three shared, human-mouse cross-species glomerular transcriptional networks containing 143 (Human-STZ), 97 (Human- db/db), and 162 (Human- eNOS-/- db/db) gene nodes were generated. Shared nodes across all networks reflected established pathogenic mechanisms of diabetic complications, such as elements of JAK-STAT and VEGFR signaling pathways . In addition, novel pathways not formally associated with DN and cross-species gene nodes and pathways unique to each of the human-mouse networks were discovered. The human-mouse shared glomerular transcriptional networks will assist DN researchers in the selection of mouse models most relevant to the human disease process of interest. Moreover, they will allow identification of new pathways shared between mice and humans.
Identification of cross-species shared transcriptional networks of diabetic nephropathy in human and mouse glomeruli.
Age, Specimen part, Disease, Disease stage, Treatment
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