Project description:The H19 large intergenic non-coding RNA (lincRNA) is one of the most highly abundant and conserved transcripts in mammalian development, being expressed in both embryonic and extra-embryonic cell lineages, yet its physiological function is unknown. Here we show that miR-675, a microRNA (miRNA) embedded in H19's first exon, is expressed exclusively in the placenta from the gestational time point when placental growth normally ceases, and placentas that lack H19 continue to grow. Overexpression of miR-675 in a range of embryonic and extra-embryonic cell lines results in their reduced proliferation; targets of the miRNA are upregulated in the H19 null placenta, including the growth-promoting insulin-like growth factor 1 receptor (Igf1r) gene. Moreover, the excision of miR-675 from H19 is dynamically regulated by the stress-response RNA-binding protein HuR. These results suggest that H19's main physiological role is in limiting growth of the placenta before birth, by regulated processing of miR-675. The controlled release of miR-675 from H19 may also allow rapid inhibition of cell proliferation in response to cellular stress or oncogenic signals.
Project description:Changes in microRNA expression in Igf2-p and H19-m mouse embryos (E9.5) were determined in order to assess whether perturbation of miR-483* and miR-675 in Igf2-p and H19-m mutants was likely to have contributed to a modification of tumour phenotype. The Igf2 gene contains miR-483* but the targeted deletion of Igf2-p in these mice spares the region encoding this microRNA. The H19 gene contains miR-675 and its expression was mono-allelelic in heterozygous H19-m mice as evidenced by a significant reduction in miR-675 in these mice relative to WT.
Project description:Igf2 and H19 are linked, reciprocally imprinted genes that play critical roles in mammalian development. Igf2 encodes a peptide hormone, Insulin-like Growth Factor 2, that binds to the InsR and Igf1R receptor kinases to regulate cell growth and metabolism through well-established pathways. H19 encodes a 2.3 kb lncRNA whose biochemical actions are only now being identified. Here we use a mouse model to investigate cardiomyopathies associated with maternal loss of imprinting at the locus. Increased circulating levels of IGF2 during fetal development result in activation of pAKT/mTOR signaling in cardiomyocytes to cause cellular hypertrophy and hyperplasia in neonatal hearts. This neonatal hypertrophy is unaffected by H19 RNA levels. However, loss of H19 does cause fibrosis and progressive cardiac pathology in adult mice. In hearts, H19 expression is concentrated in endothelial cells associated with blood vessels and capillaries and loss of H19 results in high incidence of trans differentiation of these cells to smooth muscle. H19 encoded miRNAs 675-3p and -5p are not sufficient to promote normal development. Thus these experiments define a novel role for the H19 lncRNA in regulating cell fate.
Project description:Increases in organismal energy expenditure, as during cold exposure or exercise training, can improve metabolic health. This process is dependent also on brown adipose tissue (BAT) thermogenesis in mice and humans. Understanding and harnessing the molecular circuits activating BAT function is thus of great interest to devise novel approaches to counteract obesity and type 2 diabetes (T2D). In contrast to protein-coding genes, the role of long noncoding RNAs (lncRNAs) during BAT differentiation and function remains poorly understood. To address this, we performed RNA-Seq and identified the maternal allele-specific (imprinted) lncRNA H19 increased upon cold-mediated BAT activation and decreased upon chronic diet-induced obesity (DIO) BAT dysfunction. An inverse correlation of H19 expression with body-mass indices (BMI) was observed in a cohort of >160 lean and obese humans. H19 silencing impaired adipogenesis and oxidative metabolism in brown but not white adipocytes, while H19 gain-of-function increased nutrient oxidation and mitochondrial respiration, thus supporting a BAT-regulatory role for H19. In vivo H19 overexpression protected against DIO, improved insulin sensitivity and rescued DIO-mediated defects in energy expenditure in conjunction with improved mitochondrial biogenesis. In contrast, BAT-selective H19 loss decreased energy dissipation and sensitized towards high fat diet-induced body weight gains. When investigating other parent-of-origin specific, monoallelically expressed genes, we strikingly observed that paternally expressed genes (PEGs) were largely absent from BAT and coordinately downregulated during brown adipogenesis, whilst the same gene set was robustly expressed in white fat stores, a phenomenon not observed for maternally expressed genes (MEGs). Using H19 loss- and gain-of-function in primary adipocytes, we demonstrate that H19 acts as ‘PEG gatekeeper’ in brown, not white adipocytes, potentially due to recruitment of PEG-inactivating H19-MBD1 complexes in mature brown adipocytes. The exclusive PEG expression in white adipose tissuer could underly the observed susceptibility of mice exhibiting high PEG abundances towards DIO-evoked weight gain. Collectively, we here define novel roles for the imprinted lncRNA H19 in brown adipocyte differentiation and function in vitro, control of energy expenditure in vivo and repression of paternal allele-specific gene expression in BAT. This has far-reaching implications for our understanding of how monoallelical gene expression affects metabolic eustasis in both rodent models and, potentially, human patients.
Project description:Increases in organismal energy expenditure, as during cold exposure or exercise training, can improve metabolic health. This process is dependent also on brown adipose tissue (BAT) thermogenesis in mice and humans. Understanding and harnessing the molecular circuits activating BAT function is thus of great interest to devise novel approaches to counteract obesity and type 2 diabetes (T2D). In contrast to protein-coding genes, the role of long noncoding RNAs (lncRNAs) during BAT differentiation and function remains poorly understood. To address this, we performed RNA-Seq and identified the maternal allele-specific (imprinted) lncRNA H19 increased upon cold-mediated BAT activation and decreased upon chronic diet-induced obesity (DIO) BAT dysfunction. An inverse correlation of H19 expression with body-mass indices (BMI) was observed in a cohort of >160 lean and obese humans. H19 silencing impaired adipogenesis and oxidative metabolism in brown but not white adipocytes, while H19 gain-of-function increased nutrient oxidation and mitochondrial respiration, thus supporting a BAT-regulatory role for H19. In vivo H19 overexpression protected against DIO, improved insulin sensitivity and rescued DIO-mediated defects in energy expenditure in conjunction with improved mitochondrial biogenesis. In contrast, BAT-selective H19 loss decreased energy dissipation and sensitized towards high fat diet-induced body weight gains. When investigating other parent-of-origin specific, monoallelically expressed genes, we strikingly observed that paternally expressed genes (PEGs) were largely absent from BAT and coordinately downregulated during brown adipogenesis, whilst the same gene set was robustly expressed in white fat stores, a phenomenon not observed for maternally expressed genes (MEGs). Using H19 loss- and gain-of-function in primary adipocytes, we demonstrate that H19 acts as ‘PEG gatekeeper’ in brown, not white adipocytes, potentially due to recruitment of PEG-inactivating H19-MBD1 complexes in mature brown adipocytes. The exclusive PEG expression in white adipose tissuer could underly the observed susceptibility of mice exhibiting high PEG abundances towards DIO-evoked weight gain. Collectively, we here define novel roles for the imprinted lncRNA H19 in brown adipocyte differentiation and function in vitro, control of energy expenditure in vivo and repression of paternal allele-specific gene expression in BAT. This has far-reaching implications for our understanding of how monoallelical gene expression affects metabolic eustasis in both rodent models and, potentially, human patients.
Project description:IntroductionBreast cancer, as the most prevalent malignancy among women globally, continues to exhibit rising incidence rates, particularly in China. The disease predominantly affects women aged 40 to 60 and is influenced by both genetic and environmental factors. This study focuses on the role of H19 gene polymorphisms, investigating their impact on breast cancer susceptibility, clinical outcomes, and response to treatment.MethodsWe engaged 581 breast cancer patients and 558 healthy controls, using TaqMan assays and DNA sequencing to determine genotypes at specific loci (rs11042167, rs2071095, rs2251375). We employed in situ hybridization and immunohistochemistry to measure the expression levels of LincRNA H19, miR-675, MRP3, HOXA1, and MMP16 in formalin-fixed, paraffin-embedded samples. Statistical analyses included chi-squared tests, logistic regression, and Kaplan-Meier survival curves to evaluate associations between genetic variations, gene expression, and clinical outcomes.ResultsGenotypes AG at rs11042167, GT at rs2071095, and AC at rs2251375 were significantly associated with increased risk of breast cancer. Notably, the AA genotype at rs11042167 and TT genotype at rs2071095 were linked to favorable prognosis. High expression levels of LincRNA H19, miR-675, MRP3, HOXA1, and MMP16 in cancer tissues correlated with advanced disease stages and poorer survival rates. Spearman correlation analysis revealed significant positive correlations between the expression of LincRNA H19 and miR-675 and specific genotypes, highlighting their potential regulatory roles in tumor progression.DiscussionThe study underscores the critical roles of LincRNA H19 and miR-675 as prognostic biomarkers in breast cancer, with their overexpression associated with disease progression and adverse outcomes. The H19/LincRNA H19/miR-675/MRP3-HOXA1-MMP16 axis offers promising targets for new therapeutic strategies, reflecting the complex interplay between genetic markers and breast cancer pathology.ConclusionThe findings confirm that certain H19 SNPs are associated with heightened breast cancer risk and that the expression profiles of related genetic markers can significantly influence prognosis and treatment response. These biomarkers hold potential as targets for personalized therapy and early detection strategies in breast cancer, underscoring the importance of genetic research in understanding and managing this disease.