Project description:In mammals, Wnt pathway is activated during both heart regeneration post-injury and disease. Our previous work described the role of nuclear Wnt effectors B-catenin and Transcription factor 7-like 2 (TCF7L2) in heart disease progression; revealing GATA4 as a Wnt-repressor in the healthy adult heart. However, there is an urgent need to dissect molecular players distinguishing regenerative vs. disease-specific responses. In this study, we report a GATA4-B-catenin interaction in the regenerative neonatal myocardium, despite high TCF7L2 expression. TCF7L2 displayed strikingly unique genomic occupancies: proximal in neonatal and distal in diseased hearts. Integrative genomic and transcriptomic analyses showed that TCF7L2 differentially occupied and regulated fatty acid metabolic genes in the neonatal; and cardiac developmental and vasculogenesis genes in the diseased hearts, clearly discerning these two cardiac states. De-novo motif search identified TEAD as a commonly enriched motif in both TCF7L2 and GATA4-bound regions in the neonatal hearts, suggesting its potential role in providing a regenerative context to this GATA4-B-catenin interaction. Altogether, our study mapped for the first time, novel genome-wide TCF7L2 and GATA4 targets in the neonatal hearts and identified stage-specific roles for the cardiac Wnt-GATA4 complex. These findings demonstrate strong context-specificity of the cardiac Wnt-nuclear complex, which can be further exploited for therapeutic avenues. Purpose: The aim of this study was to investigate the transcriptome profiles (RNA-seq) of WT postnatal day 6 murine cardiac ventricles; and compare them to our previously published (GSE97762) adult and diseased myocardium transcriptomes. Methods: P6 cardiac ventricular tissue mRNA profiles were obtained using deep sequencing, in triplicates, using Illumina HiSeq4000. The sequence reads that passed quality filters were analyzed at the transcript isoform level with TopHat followed by DESeq2. qPCR validation was performed using TaqMan and SYBR Green assays Conclusions: Our study identified distinct transcriptomic signatures of P6 murine cardiac ventricles, in comparison to healthy or diseased adult heart. Particularly, despite high Wnt signaling activities and cardiomyocytes cell cycling in both P6 and diseased hearts, P6 hearts are regenerative in nature, while the diseased hearts are not.

Project description:TCF7L2 is one of the strongest type 2 diabetes (T2DM) candidate genes to emerge from GWAS studies, but the mechanisms by which it regulates the pathways which are important in the pathogenesis of type 2 diabetes are unknown. Previous in vitro and in vivo studies have focused on the link between TCF7L2 and insulin secretion as an explanation for the association between TCF7L2 and T2DM. However, TCF7L2 and the Wnt/β-catenin pathway are important for metabolic zonation in the liver. This raises the interesting possibility that TCF7L2 may influence glucose homeostasis by regulating hepatic glucose production (HGP). To examine this question, we utilized the H4IIE cell as a model of HGP. Inhibition of HGP in H4IIE cells from lactate and pyruvate was highly sensitive to physiological concentrations of insulin and metformin. Silencing of TCF7L2 protein expression induced a 5-fold increase in basal HGP (P<0.0001), and this was accompanied by marked increase in the expression of several key gluconeogenic genes. FBPase, PEPCK and G6Pase mRNA were up-regulated 2.5-fold (P<0.0001), 1.4-fold (P<0.01) and 2.3-fold (P<0.0001), respectively, compared to scramble siRNA. Compared to their respective baseline values, insulin and metformin suppressed HGP equally in the scramble and TCF7L2 siRNA cells, but HGP remained elevated in TCF7L2 silenced cells due to the increased baseline HGP. Using chromatin immunoprecipitation sequencing (ChIP-Seq), we investigated the direct transcriptional targets of TCF7L2 in hepatocytes. A total of 2119 ChIP peaks were detected, of which 36% were located inside gene boundaries and, overall, a total of 65% of all binding events were within 50 Kb of a gene. De novo motif analysis revealed remarkable conservation of the long and short TCF7L2 consensus binding sites in the rat hepatocytes. Pathway analysis showed that the top two disease categories over-represented in our dataset were “non-insulin dependent diabetes” (155 genes; P = 1.63 x 10-10) and “diabetes mellitus” (245 genes; P = 7.4 x 10-12). Inspection of genes in these categories revealed that TCF7L2 directly binds to multiple genes important in the regulation of glucose metabolism in the liver, including PEPCK, FBP1, IRS1, IRS2, AKT2 ADIPOR1, PDK4 and CPT1A. Our findings suggest a novel mechanism for the regulation of HGP by TCF7L2, and provide a possible explanation for the association of TCF7L2 polymorphisms with the incidence of T2DM.

Project description:TCF7L2 is one of the strongest type 2 diabetes (T2DM) candidate genes to emerge from GWAS studies, but the mechanisms by which it regulates the pathways which are important in the pathogenesis of type 2 diabetes are unknown. Previous in vitro and in vivo studies have focused on the link between TCF7L2 and insulin secretion as an explanation for the association between TCF7L2 and T2DM. However, TCF7L2 and the Wnt/β-catenin pathway are important for metabolic zonation in the liver. This raises the interesting possibility that TCF7L2 may influence glucose homeostasis by regulating hepatic glucose production (HGP). To examine this question, we utilized the H4IIE cell as a model of HGP. Inhibition of HGP in H4IIE cells from lactate and pyruvate was highly sensitive to physiological concentrations of insulin and metformin. Silencing of TCF7L2 protein expression induced a 5-fold increase in basal HGP (P<0.0001), and this was accompanied by marked increase in the expression of several key gluconeogenic genes. FBPase, PEPCK and G6Pase mRNA were up-regulated 2.5-fold (P<0.0001), 1.4-fold (P<0.01) and 2.3-fold (P<0.0001), respectively, compared to scramble siRNA. Compared to their respective baseline values, insulin and metformin suppressed HGP equally in the scramble and TCF7L2 siRNA cells, but HGP remained elevated in TCF7L2 silenced cells due to the increased baseline HGP. Using chromatin immunoprecipitation sequencing (ChIP-Seq), we investigated the direct transcriptional targets of TCF7L2 in hepatocytes. A total of 2119 ChIP peaks were detected, of which 36% were located inside gene boundaries and, overall, a total of 65% of all binding events were within 50 Kb of a gene. De novo motif analysis revealed remarkable conservation of the long and short TCF7L2 consensus binding sites in the rat hepatocytes. Pathway analysis showed that the top two disease categories over-represented in our dataset were “non-insulin dependent diabetes” (155 genes; P = 1.63 x 10-10) and “diabetes mellitus” (245 genes; P = 7.4 x 10-12). Inspection of genes in these categories revealed that TCF7L2 directly binds to multiple genes important in the regulation of glucose metabolism in the liver, including PEPCK, FBP1, IRS1, IRS2, AKT2 ADIPOR1, PDK4 and CPT1A. Our findings suggest a novel mechanism for the regulation of HGP by TCF7L2, and provide a possible explanation for the association of TCF7L2 polymorphisms with the incidence of T2DM. two samples: TCF7L2 ChIP-Seq and Input DNA

			Action	DRS
	SRR8062270.fastq.gz	Fastqsanger.gz
	SRR8062271.fastq.gz	Fastqsanger.gz
	SRR8062272.fastq.gz	Fastqsanger.gz
	SRR8062273.fastq.gz	Fastqsanger.gz
	SRR8062593.fastq.gz	Fastqsanger.gz

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Distinct TCF7L2 genomic occupancies discern chromatin states in the neonatal and diseased mammalian myocardium

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