Project description:To investigate the detailed molecular mechanisms for the regulatory role of HIF-1α in colon, microarray gene expression analysis was performed on colon RNA isolated from 6- to 8-week-old Hif-1α+/+, Hif-1αLSL/LSL mice. Background & Aims: The progression and growth of solid tumors leads to a state where tumors outgrow their capacity for efficient oxygenation and nutrient uptake and an increase in tumor hypoxia. Tumor hypoxic response is mediated by hypoxia-inducible factor (HIF)-1a and HIF-2a. These transcription factors regulate a battery of genes that are critical for tumor oxygenation, tumor metabolism, and cell proliferation and survival. Therefore, inhibitors of HIF have been sought for as anti-neoplastic agents in several different kinds of cancers. Interestingly, in ischemic and inflammatory diseases of the intestine, activation of HIF-1a is beneficial, and can reduce intestinal inflammation. The efficacy of pharmacological agents that chronically activate HIF-1a are decreased due to the tumorigenic potential of HIF. However, recent advance in understanding HIF signaling have identified mechanisms, which could allow for isoform specific activators. Activation of HIF-2a increases colon carcinogenesis and progression in mouse models. However, the role of chronic HIF-1a activation is unclear in the progression in colon cancer. The present data demonstrates that activation of HIF-1a in epithelial cells does not increase colon carcinogens or progression in two mouse models of colon cancer, and provides the proof of principle that HIF-1a activation maybe safe as therapies for inflammatory bowel disease. Global gene expression profiling in colon RNAs isolated from 6- to 8-week-old Hif-1α+/+ (n=5, Shah 019) and Hif-1αLSL/LSL (n=5, Shah 020).
Project description:Background: Intestine epithelial hypoxia-inducible factor-1α (HIF-1α) plays a critical role in maintaining gut barrier function. The aim of this study was to determine genetic activation of intestinal HIF-1α ameliorates western diet-induced metabolic dysfunction–associated steatotic liver disease (MASLD). Methods: Male and/or female intestinal epithelial-specific Hif1α overexpression mice (Hif1α LSL/LSL;VilERcre) and wild-type littermates (Hif1α LSL/LSL) were fed with regular chow diet, high fructose (HFr) or high-fat (60% Kcal) high-fructose diet (HFHFr) for 8 weeks. Metabolic phenotypes were profiled. Results: Male Hif1α LSL/LSL;VilERcre mice exhibited markedly improved glucose tolerance compared to Hif1α LSL/LSL mice in response to HFr diet. Eight weeks HFHFr feeding led to obesity in both Hif1α LSL/LSL;VilERcre and Hif1α LSL/LSL mice. However, male Hif1α LSL/LSL;VilERcre mice exhibited markedly attenuated hepatic steatosis along with reduced liver size and liver weight compared to male Hif1α LSL/LSL mice. Moreover, HFHFr-induced systemic inflammatory responses were mitigated in male Hif1α LSL/LSL;VilERcre mice compared to male Hif1α LSL/LSL mice and those responses were not evident in female mice. Ileum RNA-seq analysis revealed that glycolysis/gluconeogenesis was up in male Hif1α LSL/LSL;VilERcre mice accompanied by increased epithelial cell proliferation. Conclusion: Our data provide evidence that genetic activation of intestinal HIF-1α markedly ameliorates western diet-induced MASLD in a sex-dependent manner. The underlying mechanism is likely attributed to HIF-1α activation induced upregulation of glycolysis, which, in turn, leading to enhanced epithelial cell proliferation and augmented gut barrier function.
Project description:To investigate the detailed molecular mechanisms for the regulatory role of HIF-1α in colon, microarray gene expression analysis was performed on colon RNA isolated from 6- to 8-week-old Hif-1α+/+, Hif-1αLSL/LSL mice. Background & Aims: The progression and growth of solid tumors leads to a state where tumors outgrow their capacity for efficient oxygenation and nutrient uptake and an increase in tumor hypoxia. Tumor hypoxic response is mediated by hypoxia-inducible factor (HIF)-1a and HIF-2a. These transcription factors regulate a battery of genes that are critical for tumor oxygenation, tumor metabolism, and cell proliferation and survival. Therefore, inhibitors of HIF have been sought for as anti-neoplastic agents in several different kinds of cancers. Interestingly, in ischemic and inflammatory diseases of the intestine, activation of HIF-1a is beneficial, and can reduce intestinal inflammation. The efficacy of pharmacological agents that chronically activate HIF-1a are decreased due to the tumorigenic potential of HIF. However, recent advance in understanding HIF signaling have identified mechanisms, which could allow for isoform specific activators. Activation of HIF-2a increases colon carcinogenesis and progression in mouse models. However, the role of chronic HIF-1a activation is unclear in the progression in colon cancer. The present data demonstrates that activation of HIF-1a in epithelial cells does not increase colon carcinogens or progression in two mouse models of colon cancer, and provides the proof of principle that HIF-1a activation maybe safe as therapies for inflammatory bowel disease.
Project description:Hypoxia inducible factor-1α (HIF-1α) is a critical transcription factor for the hypoxic response, angiogenesis, normal hematopoietic stem cell regulation, and cancer development. Importantly, HIF-1α is also a key regulator for immune cell activation. In order to determine whether HIF-1α is sufficient for developing MDS phenotypes, we generated blood specific inducible HIF-1α transgenic mice. Using Vav1-Cre/Rosa26-loxP-Stop-loxP (LSL) rtTA driver, stable HIF-1α can be induced in a doxycycline administration dependent manner. After induction, HIF-1α-induced mice developed thrombocytopenia, leukocytopenia, macrocytic anemia, and multi-lineage dysplasia. We also found activation of both innate and adaptive immunity in HIF-1α- induced mice compared to those from control mice. Taken together, these data suggest that HIF-1α is sufficient to trigger a variety of key MDS features
Project description:To describe the protein profile in hippocampus, colon and ileum tissue’ changing after the old faeces transplants, we adopted a quantitative label free proteomics approach.
Project description:Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors Gene expression profiles of Huh-7 cells stably expressing NDRG3-shRNA or HIF-1α-shRNA under normoxia were compared to gene expression profiles of Huh-7 stable cells under hypoxia for 6, 12 and 24 hours.
Project description:Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors Gene expression profiles of Huh-7 cells stably expressing NDRG3-shRNA or HIF-1α-shRNA under normoxia were compared to gene expression profiles of Huh-7 stable cells under hypoxia for 3, 6, 12 and 24 hours.
Project description:Hypoxia-inducible factor 1 (HIF-1) activates the transcription of genes encoding proteins that enable cells to adapt to reduced O2 availability. HIF-1 controls physiological processes that are dysregulated in cancer and heart disease, including angiogenesis, energy metabolism, and immunity. These disease processes are also characterized by increased activation of adenosine and β-adrenergic receptors, which triggers the synthesis of cyclic adenosine monophosphate (cAMP), the allosteric regulator of cAMP-dependent protein kinase A (PKA). We performed a proteomic screen in cardiomyocytes and identified PKA as a HIF-1α-interacting protein. PKA interacted with HIF-1α and phosphorylated Thr63 and Ser692 in vitro, coimmunoprecipitated with HIF-1α from cell lysates, and enhanced HIF transcriptional activity and target gene expression in human HeLa cells and rat cardiomyocytes. PKA inhibited the proteasomal degradation of HIF-1α in an O2-independent manner that required phosphorylation of Thr63 and Ser692 and was not affected by mutation of Pro402 and Pro564. PKA also stimulated the binding of the coactivator p300 to HIF- 1α to enhance its transcriptional activity and this effect was lost upon mutation of Asn803. These data establish a potential link between stimuli that increase cAMP concentrations and HIF-1α-dependent changes in gene expression, which contribute to the pathophysiology of cancer and heart disease.
Project description:Hypoxia-inducible factor 1 (HIF-1) activates the transcription of genes encoding proteins that enable cells to adapt to reduced O2 availability. HIF-1 target genes play a central role in mediating physiological processes that are dysregulated in cancer and heart disease, including angiogenesis, energy metabolism, and immunity. These disease processes are also characterized by increased activation of adenosine and β-adrenergic receptors, which triggers the synthesis of cyclic adenosine monophosphate (cAMP), the allosteric regulator of cAMP-dependent protein kinase A (PKA). We performed a proteomic screen in cardiomyocytes and identified PKA as a HIF-1α-interacting protein. PKA interacted with HIF-1α and phosphorylated Thr63 and Ser692 in vitro, co-immunoprecipitated with HIF-1α from cell lysates, and enhanced HIF transcriptional activity and target gene expression in human HeLa cells and rat cardiomyocytes. PKA inhibited the proteasomal degradation of HIF-1α in an O2-independent manner that required phosphorylation of Thr63 and Ser692 and was not affected by mutation of Pro402 and Pro564. PKA also stimulated the binding of the coactivator p300 to HIF-1α to enhance its transcriptional activity and this effect was lost upon mutation of Asn803. These data establish a potential link between stimuli that increase cAMP concentrations and HIF-1α-dependent changes in gene expression, which contribute to the pathophysiology of cancer and heart disease.