Project description:Cardiac Purkinje cells (PCs) comprise the most distal portion of the ventricular conduction system (VCS) and are essential for synchronous activation of the ventricular myocardium. Contactin-2 (CNTN2), a member of the immunoglobulin superfamily cell adhesion molecules (IgSF-CAMs), was previously identified as a marker of the VCS. Through differential transcriptional profiling we discovered two additional highly enriched IgSF-CAMs in the VCS, NCAM-1 and ALCAM. Immunofluorescence staining showed dynamic expression patterns for each IgSF-CAM during embryonic and early post-natal stages, but ultimately all three proteins became highly enriched in mature PCs. Mice deficient in NCAM-1, but not CNTN2 or ALCAM, exhibited defects in Purkinje cell gene expression and VCS patterning, as well as cardiac conduction disease. Moreover, using ST8sia2 and ST8sia4 knockout mice, we show that inhibition of post-translational modification of NCAM-1 by polysialic acid (PSA) disrupts trafficking of sarcolemmal intercalated disc proteins to Purkinje cell junctional membranes and abnormal expansion of the extracellular space between apposing Purkinje cells. Taken together, our data provide novel insights into the complex developmental biology of the ventricular conduction system.
Project description:Here, we identify the transcription factor IRX5 as a promoter of HFSC activation. Irx5-/- mice display delayed onset of first postnatal anagen, with increased DNA damage and diminished HFSC proliferation. Through transcriptomic and epigenetic analysis, we discover the formation of open chromatin regions near key cell cycle progression- and DNA damage repair genes in Irx5-/- HFSC. We also identify DNA damage repair factors BRCA1 and BARD1 as IRX5 downstream targets. Inhibition of FGF18 kinase signaling partially rescues the anagen delay in Irx5-/- mice, indicating that the Irx5-/- HFSC quiescent phenotype is in part due to failure to suppress Fgf18 expression. Our findings identify IRX5 as a required promoter of DNA damage repair in HFSC activation and hair cycle initiation.
Project description:Here, we identify the transcription factor IRX5 as a promoter of HFSC activation. Irx5-/- mice display delayed onset of first postnatal anagen, with increased DNA damage and diminished HFSC proliferation. Through transcriptomic and epigenetic analysis, we discover the formation of open chromatin regions near key cell cycle progression- and DNA damage repair genes in Irx5-/- HFSC. We also identify DNA damage repair factors BRCA1 and BARD1 as IRX5 downstream targets. Inhibition of FGF18 kinase signaling partially rescues the anagen delay in Irx5-/- mice, indicating that the Irx5-/- HFSC quiescent phenotype is in part due to failure to suppress Fgf18 expression. Our findings identify IRX5 as a required promoter of DNA damage repair in HFSC activation and hair cycle initiation.
Project description:Here, we identify the transcription factor IRX5 as a promoter of HFSC activation. Irx5-/- mice display delayed onset of first postnatal anagen, with increased DNA damage and diminished HFSC proliferation. Through transcriptomic and epigenetic analysis, we discover the formation of open chromatin regions near key cell cycle progression- and DNA damage repair genes in Irx5-/- HFSC. We also identify DNA damage repair factors BRCA1 and BARD1 as IRX5 downstream targets. Inhibition of FGF18 kinase signaling partially rescues the anagen delay in Irx5-/- mice, indicating that the Irx5-/- HFSC quiescent phenotype is in part due to failure to suppress Fgf18 expression. Our findings identify IRX5 as a required promoter of DNA damage repair in HFSC activation and hair cycle initiation.
Project description:Here, we identify the transcription factor IRX5 as a promoter of HFSC activation. Irx5-/- mice display delayed onset of first postnatal anagen, with increased DNA damage and diminished HFSC proliferation. Through transcriptomic and epigenetic analysis, we discover the formation of open chromatin regions near key cell cycle progression- and DNA damage repair genes in Irx5-/- HFSC. We also identify DNA damage repair factors BRCA1 and BARD1 as IRX5 downstream targets. Inhibition of FGF18 kinase signaling partially rescues the anagen delay in Irx5-/- mice, indicating that the Irx5-/- HFSC quiescent phenotype is in part due to failure to suppress Fgf18 expression. Our findings identify IRX5 as a required promoter of DNA damage repair in HFSC activation and hair cycle initiation.
Project description:Here, we identify the transcription factor IRX5 as a promoter of HFSC activation. Irx5-/- mice display delayed onset of first postnatal anagen, with increased DNA damage and diminished HFSC proliferation. Through transcriptomic and epigenetic analysis, we discover the formation of open chromatin regions near key cell cycle progression- and DNA damage repair genes in Irx5-/- HFSC. We also identify DNA damage repair factors BRCA1 and BARD1 as IRX5 downstream targets. Inhibition of FGF18 kinase signaling partially rescues the anagen delay in Irx5-/- mice, indicating that the Irx5-/- HFSC quiescent phenotype is in part due to failure to suppress Fgf18 expression. Our findings identify IRX5 as a required promoter of DNA damage repair in HFSC activation and hair cycle initiation.
Project description:Analysis of the roles of Irx3 and Irx5 transcription factors in mouse heart development and postnatal heart function. Results show that show that Irx3 and Irx5 have redundant function in the in the endocardium to regulate atrioventricular canal morphogenesis and outflow tract formation. A postnatal deletion of Irx3 and Irx5 surprisingly results in a restoration of the repolarization gradient that is altered in Irx5 mutant hearts, suggesting a model whereby postnatal Irx3 activity is normally repressed by Irx5. 4 genotypes were analyzed: Irx5+/- (3 samples), Irx3-/-;Irx5+/- (4 samples), Irx5-/- (3 samples), Irx5-/-;Irx3-/- (4 samples). The Irx5+/- samples are the reference.
Project description:Sudden cardiac death is the number one cause of death worldwide. Major causes of sudden cardiac death include myocardial infarction and cardiomyopathies. To develop novel therapeutic strategies, we need to identify key factors that are required for proper cardiac function and are dysregulated in the diseased heart. Under this notion, we found T-box 5 (TBX5), a transcription factor regarded solely in the context of congenital heart disease, to be downregulated in human diseased left ventricles. To investigate the effects of TBX5 loss in the adult heart, we generated an inducible ventricular cardiomyocyte specific knock-out mouse model (vTbx5KO). We performed integrative genome-wide chromatin occupancy and transcriptomic analysis and identified 47 downregulated transcripts in vTbx5KO that contain TBX5 active enhancers. The TBX5 targets in the ventricle included genes implicated in cardiac conduction and contraction (Gja1, Kcnj5, Kcng2, Cacna1g, Chrm2), cytoskeleton organization (Fstl4, Pdlim4, Emilin2, Cmya5) as well as cardiac protection upon stress (Fhl2, Gpr22, Fgf16). In line with this analysis, vTbx5KO mice presented cardiac conduction defects and arrhythmias at baseline as well as exacerbated cardiac remodeling upon Angiotensin II-induced hypertrophy. In conclusion, this study uncovers a novel protective role of TBX5 upon cardiac remodeling and renders TBX5 as an interesting therapeutic target.
Project description:Sudden cardiac death is the number one cause of death worldwide. Major causes of sudden cardiac death include myocardial infarction and cardiomyopathies. To develop novel therapeutic strategies, we need to identify key factors that are required for proper cardiac function and are dysregulated in the diseased heart. Under this notion, we found T-box 5 (TBX5), a transcription factor regarded solely in the context of congenital heart disease, to be downregulated in human diseased left ventricles. To investigate the effects of TBX5 loss in the adult heart, we generated an inducible ventricular cardiomyocyte specific knock-out mouse model (vTbx5KO). We performed integrative genome-wide chromatin occupancy and transcriptomic analysis and identified 47 downregulated transcripts in vTbx5KO that contain TBX5 active enhancers. The TBX5 targets in the ventricle included genes implicated in cardiac conduction and contraction (Gja1, Kcnj5, Kcng2, Cacna1g, Chrm2), cytoskeleton organization (Fstl4, Pdlim4, Emilin2, Cmya5) as well as cardiac protection upon stress (Fhl2, Gpr22, Fgf16). In line with this analysis, vTbx5KO mice presented cardiac conduction defects and arrhythmias at baseline as well as exacerbated cardiac remodeling upon Angiotensin II-induced hypertrophy. In conclusion, this study uncovers a novel protective role of TBX5 upon cardiac remodeling and renders TBX5 as an interesting therapeutic target.