Project description:We have developed gene-targeted mice with deletion of Nkx2.5. Embryos were isolated at embryonic day 9.5 and the middle third containing the heart was run on Affymetrix Mu11kA and Mu11kB arrays. For more information about this model see http://cardiogenomics.med.harvard.edu/groups/proj1/pages/csx_home.html Keywords = Congenital heart disease Keywords: other
Project description:Lack of the conserved NK2-domain of the cardiac transcription factor Nkx2.5 causes multiple heart defects . The NK2 family of homeobox genes constitutes a family of transcription factors that play an important role in different developmental processes. Members of this group are characterized by two highly conserved protein domains: the homeodomain, conferring DNA binding activity, and the NK2-specific domain (NK2-SD) of yet unknown function. One of the best characterized members of this group is the early cardiogenic marker Nkx2.5. Loss of function of Nkx2.5 leads to embryonic lethality around E10.5 due to an arrest of heart development at the looping stage. We have further dissected the function of Nkx2.5 in vivo by creating a knockout mouse line harboring an in frame deletion of the NK2-SD by Cre/loxP mediated excision. Homozygous mutant mice die at E14.5 due to severe cardiac malformations, e.g. common AV canal, DORV, and VSD. Lack of the NK2-SD leads to downregulation of the ventricular markers MLC-2v and Irx4 specifically in the right ventricle, and is accompanied with reduced right ventricular function. This function of Nkx2.5 seems to be independent of its ability to bind target DNA, since lack of the NK2-SD does not alter the DNA binding activity of Csx/Nkx2.5 in vitro. Heterozygous mutant mice show a spectrum of cardiac defects related to cardiac septation and valve morphogenesis, but lack conduction system defects as reported for heterozygous Nkx2.5 mice. The phenotype observed in NK2-SD mutant mice shows that Nkx2.5 is not only crucial during early steps of cardiogenesis but also plays an important role at later developmental stages. Embryos were isolated at embryonic day 12.5. The entire embryo heart was taken and isolated in ice-cold PBS and immediately frozen on dry-ice. Total RNA was extracted from pooled samples of wildtype, heterozygous and mutant embryos. Keywords = congenital heart disease, Csx, Nkx2.5 Keywords: other
Project description:Maintenance of cardiomyocyte identity is vital for normal heart development and function. However, our understanding of cardiomyocyte plasticity remains incomplete. Here, we show that sustained expression of the zebrafish transcription factor Nr2f1a prevents the progressive acquisition of ventricular cardiomyocyte (VC) and pacemaker cardiomyocyte (PC) identities within distinct regions of the atrium. Transcriptomic analysis of flow-sorted atrial cardiomyocytes (ACs) from nr2f1a mutant zebrafish embryos showed increased VC marker gene expression and altered expression of core PC regulatory genes, including decreased expression of nkx2.5, a critical repressor of PC differentiation. At the arterial (outflow) pole of the atrium in nr2f1a mutants, cardiomyocytes resolve to VC identity within the expanded atrioventricular canal. However, at the venous (inflow) pole of the atrium, there is a progressive wave of AC transdifferentiation into PCs across the atrium toward the arterial pole. Restoring Nkx2.5 is sufficient to repress PC marker identity in nr2f1a mutant atria and analysis of chromatin accessibility identified a Nr2f1a-dependent nkx2.5 enhancer expressed in the atrial myocardium directly adjacent to PCs. CRISPR/Cas9-mediated deletion of the putative nkx2.5 enhancer leads to a loss of Nkx2.5-expressing ACs and expansion of a PC reporter, supporting that Nr2f1a limits PC differentiation within venous ACs via maintaining nkx2.5 expression. The Nr2f-dependent maintenance of AC identity within discrete atrial compartments may provide insights into the molecular etiology of concurrent structural congenital heart defects and associated arrhythmias.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:The NK2 family of homeobox genes constitutes a family of transcription factors that play an important role in different developmental processes. Members of this group are characterized by two highly conserved protein domains: the homeodomain, conferring DNA binding activity, and the NK2-specific domain (NK2-SD) of yet unknown function. One of the best characterized members of this group is the early cardiogenic marker Nkx2.5. Loss of function of Nkx2.5 leads to embryonic lethality around E10.5 due to an arrest of heart development at the looping stage. We have further dissected the function of Nkx2.5 in vivo by creating a knockout mouse line harboring an in frame deletion of the NK2-SD by Cre/loxP mediated excision. Homozygous mutant mice die at E14.5 due to severe cardiac malformations, e.g. common AV canal, DORV, and VSD. Lack of the NK2-SD leads to downregulation of the ventricular markers MLC-2v and Irx4 specifically in the right ventricle, and is accompanied with reduced right ventricular function. This function of Nkx2.5 seems to be independent of its ability to bind target DNA, since lack of the NK2-SD does not alter the DNA binding activity of Csx/Nkx2.5 in vitro. Heterozygous mutant mice show a spectrum of cardiac defects related to cardiac septation and valve morphogenesis, but lack conduction system defects as reported for heterozygous Nkx2.5 mice. The phenotype observed in NK2-SD mutant mice shows that Nkx2.5 is not only crucial during early steps of cardiogenesis but also plays an important role at later developmental stages. Embryos were isolated at embryonic day 12.5. The entire embryo heart was taken and isolated in ice-cold PBS and immediately frozen on dry-ice. Total RNA was extracted from pooled samples of wildtype, heterozygous and mutant embryos.
Project description:Rationale: 22q11 deletion syndrome arises from recombination between low copy repeats on chromosome 22. Typical deletions result in hemizygosity for TBX1 associated with congenital cardiovascular disease. Deletions distal to the typically deleted region result in a similar cardiac phenotype but lack extra-cardiac features of the syndrome suggesting that a second haploinsufficient gene maps to this interval. Objective: The transcription factor HIC2 is lost in most distal deletions as well as a minority of typical deletions. We used mouse models to test the hypothesis that HIC2 hemizygosity causes congenital heart disease. Methods and Results: We created a genetrap mouse allele of Hic2. The genetrap reporter was expressed in the heart throughout the key stages of cardiac morphogenesis. Homozygosity for the genetrap allele was embryonic lethal before embryonic day E10.5 while the heterozygous condition exhibited a partially penetrant late lethality. One third of heterozygous embryos had a cardiac phenotype. Magnetic resonance imaging demonstrated a ventricular septal defect with overriding aorta. Conditional targeting indicated a requirement for Hic2 within the Nkx2.5+ and Mesp1+ cardiovascular progenitor lineages but not in the Wnt1+ neural crest or Mef2c+ second heart field lineages. Microarray analysis revealed increased expression of BMP10. Conclusions: Our results demonstrate a novel role for Hic2 in cardiac development. Hic2 is the first gene within the distal 22q11 interval to have a demonstrated haploinsufficient cardiac phenotype in mice. Together our data suggests HIC2 haploinsufficiency likely contributes to the cardiac defects seen in distal 22q11 deletion syndrome. The aim of this microarray experiment was to compare gene expression changes in the E13.5 mouse heart in a conditional knockout of Hic2 (Mesp1Cre/+; Hic2FL/FL) against control. All samples represent pools of isolated hearts from E13.5 mouse embryos. 3 replicates of each genotype were assayed. The genotypes are: 'WT' (Hic2FL/FL) 'KO' (Mesp1Cre/+; Hic2 FL/FL)