Hypoxia Directs Human Extravillous Trophoblast Differentiation in a Hypoxia-Inducible Factor–Dependent Manner

Abstract Embryonic stem cells and embryonal carcinoma P19 cells produce erythropoietin (Epo) in an oxygen-independent manner, although lactate dehydrogenase A (LDHA) is hypoxia-inducible. To explore this paradox, we studied the operation of cis-acting sequences from these genes in P19 and Hep3B cells. The Epo gene promoter and 3′ enhancer from P19 cells conveyed hypoxia-inducible responses in Hep3B cells but not in P19 cells. Together with DNA sequencing and the normal transcription start site of P19 Epo gene, this excluded the possibility that the noninducibility of Epo gene in P19 cells was due to mutation in these sequences or unusual initiation of transcription. In contrast, reporter constructs containing LDHA enhancer and promoter were hypoxia inducible in P19 and Hep3B cells, and mutation of a hypoxia- inducible factor 1 (HIF-1) binding site abolished the hypoxic inducibility in both cells, indicating that HIF-1 activation operates normally in P19 cells. Neither forced expression of hepatocyte nuclear factor 4 in P19 cells nor deletion of its binding site from the Epo enhancer was effective in restoring Epo enhancer function. P19 cells may lack an unidentified regulator(s) required for interaction of the Epo enhancer with Epo and LDHA promoters.

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Vitamin D/VDR signaling inhibits colitis by suppressing HIF-1α activation in colonic epithelial cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00061.2021 ◽

2021 ◽

Author(s):

Gang Xue ◽

Ruifang Gao ◽

Zhuanzhuan Liu ◽

Na Xu ◽

Yong Cao ◽

...

Keyword(s):

Vitamin D ◽

Animal Models ◽

Epithelial Cells ◽

Dextran Sulfate ◽

Hypoxia Inducible Factor ◽

Dependent Manner ◽

Trinitrobenzenesulfonic Acid ◽

Colonic Epithelial Cells ◽

Bowel Diseases ◽

Inflammatory Bowel

Vitamin D/vitamin D receptor (VDR) signaling is reported to have a protective effect on the onset or progression of inflammatory bowel diseases (IBD) and hypoxia-inducible factor 1α (HIF-1α) activation is demonstrated to be closely associated with chemical-induced colitis. However, the association between vitamin D/VDR signaling and HIF-1α on IBD development remains a mystery. Here, we showed that HIF-1α expression was largely increased in the colonic epithelial cells of diseased tissues from ulcerative colitis (UC) patients. Consistently, HIF-1α activation was also improved in colonic epithelial cells upon TNFα treatment in a NF-κB pathway-dependent manner. HIF-1α inhibitors treatments ameliorated 2,4,6-trinitrobenzenesulfonic acid (TNBS)- or dextran sulfate sodium (DSS)-induced colitis in animal models. In cell or colitis animal models, vitamin D/VDR signaling suppressed HIF-1α overexpression in colonic epithelial cells via regulating NF-κB pathway, resulting in the inhibition of IFNγ and IL-1β overproductions in these cells. Collectively, these data suggest that vitamin D/VDR signaling relieves colitis development in animal models, at least in part, by suppressing HIF-1α expression in colonic epithelial cells.

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The Hypoxia-Inducible Factor 1/NOR-1 Axis Regulates the Survival Response of Endothelial Cells to Hypoxia

Molecular and Cellular Biology ◽

10.1128/mcb.00945-09 ◽

2009 ◽

Vol 29 (21) ◽

pp. 5828-5842 ◽

Cited By ~ 42

Author(s):

Lluis Martorell ◽

Maurizio Gentile ◽

Jordi Rius ◽

Cristina Rodríguez ◽

Javier Crespo ◽

...

Keyword(s):

Endothelial Cells ◽

Transcriptional Activation ◽

Hypoxia Inducible Factor ◽

Orphan Receptor ◽

Vegf Receptor ◽

Mrna Levels ◽

Dependent Manner ◽

Small Interfering Rnas ◽

Hypoxia Inducible Factor 1 ◽

Apoptosis Protein

ABSTRACT Hypoxia induces apoptosis but also triggers adaptive mechanisms to ensure cell survival. Here we show that the prosurvival effects of hypoxia-inducible factor 1 (HIF-1) in endothelial cells are mediated by neuron-derived orphan receptor 1 (NOR-1). The overexpression of NOR-1 decreased the rate of endothelial cells undergoing apoptosis in cultures exposed to hypoxia, while the inhibition of NOR-1 increased cell apoptosis. Hypoxia upregulated NOR-1 mRNA levels in a time- and dose-dependent manner. Blocking antibodies against VEGF or SU5614 (a VEGF receptor 2 inhibitor) did not prevent hypoxia-induced NOR-1 expression, suggesting that NOR-1 is not induced by the autocrine secretion of VEGF in response to hypoxia. The reduction of HIF-1α protein levels by small interfering RNAs, or by inhibitors of the phosphatidylinositol-3 kinase (PI3K)/Akt pathway or mTOR, significantly counteracted hypoxia-induced NOR-1 upregulation. Intracellular Ca2+ was involved in hypoxia-induced PI3K/Akt activation and in the downstream NOR-1 upregulation. A hypoxia response element mediated the transcriptional activation of NOR-1 induced by hypoxia as we show by transient transfection and chromatin immunoprecipitation assays. Finally, the attenuation of NOR-1 expression reduced both basal and hypoxia-induced cIAP2 (cellular inhibitor of apoptosis protein 2) mRNA levels, while NOR-1 overexpression upregulated cIAP2. Therefore, NOR-1 is a downstream effector of HIF-1 signaling involved in the survival response of endothelial cells to hypoxia.

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HIF-1-mediated production of exosomes during hypoxia is protective in renal tubular cells

AJP Renal Physiology ◽

10.1152/ajprenal.00178.2017 ◽

2017 ◽

Vol 313 (4) ◽

pp. F906-F913 ◽

Cited By ~ 37

Author(s):

Wei Zhang ◽

Xiangjun Zhou ◽

Qisheng Yao ◽

Yutao Liu ◽

Hao Zhang ◽

...

Keyword(s):

Cell Injury ◽

Hypoxia Inducible Factor ◽

Atp Depletion ◽

Tubular Cell ◽

Renal Tubular Cell ◽

Dependent Manner ◽

Protective Effects ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Exosomes are nano-sized vesicles produced and secreted by cells to mediate intercellular communication. The production and function of exosomes in kidney tissues and cells remain largely unclear. Hypoxia is a common pathophysiological condition in kidneys. This study was designed to characterize exosome production during hypoxia of rat renal proximal tubular cells (RPTCs), investigate the regulation by hypoxia-inducible factor-1 (HIF-1), and determine the effect of the exosomes on ATP-depletion-induced tubular cell injury. Hypoxia did not change the average sizes of exosomes secreted by RPTCs, but it significantly increased exosome production in a time-dependent manner. HIF-1 induction with dimethyloxalylglycine also promoted exosome secretion, whereas pharmacological and genetic suppression of HIF-1 abrogated the increase of exosome secretion under hypoxia. The exosomes from hypoxic RPTCs had inhibitory effects on apoptosis of RPTCs following ATP depletion. The protective effects were lost in the exosomes from HIF-1α knockdown cells. It is concluded that hypoxia stimulates exosome production and secretion in renal tubular cells. The exosomes from hypoxic cells are protective against renal tubular cell injury. HIF-1 mediates exosome production during hypoxia and contributes to the cytoprotective effect of the exosomes.

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HER2 (neu) Signaling Increases the Rate of Hypoxia-Inducible Factor 1α (HIF-1α) Synthesis: Novel Mechanism for HIF-1-Mediated Vascular Endothelial Growth Factor Expression

Molecular and Cellular Biology ◽

10.1128/mcb.21.12.3995-4004.2001 ◽

2001 ◽

Vol 21 (12) ◽

pp. 3995-4004 ◽

Cited By ~ 873

Author(s):

Erik Laughner ◽

Panthea Taghavi ◽

Kelly Chiles ◽

Patrick C. Mahon ◽

Gregg L. Semenza

Keyword(s):

Breast Cancer ◽

Vascular Endothelial Growth Factor ◽

Growth Factor ◽

Cancer Cells ◽

Half Life ◽

Hypoxia Inducible Factor ◽

Dependent Manner ◽

Vascular Endothelial ◽

Her2 Signaling ◽

Endothelial Growth Factor

ABSTRACT Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator composed of HIF-1α and HIF-1β subunits. Several dozen HIF-1 targets are known, including the gene encoding vascular endothelial growth factor (VEGF). Under hypoxic conditions, HIF-1α expression increases as a result of decreased ubiquitination and degradation. The tumor suppressors VHL (von Hippel-Lindau protein) and p53 target HIF-1α for ubiquitination such that their inactivation in tumor cells increases the half-life of HIF-1α. Increased phosphatidylinositol 3-kinase (PI3K) and AKT or decreased PTEN activity in prostate cancer cells also increases HIF-1α expression by an undefined mechanism. In breast cancer, increased activity of the HER2 (also known as neu) receptor tyrosine kinase is associated with increased tumor grade, chemotherapy resistance, and decreased patient survival. HER2 has also been implicated as an inducer of VEGF expression. Here we demonstrate that HER2 signaling induced by overexpression in mouse 3T3 cells or heregulin stimulation of human MCF-7 breast cancer cells results in increased HIF-1α protein and VEGF mRNA expression that is dependent upon activity of PI3K, AKT (also known as protein kinase B), and the downstream kinase FRAP (FKBP-rapamycin-associated protein). In contrast to other inducers of HIF-1 expression, heregulin stimulation does not affect the half-life of HIF-1α but instead stimulates HIF-1α synthesis in a rapamycin-dependent manner. The 5′-untranslated region of HIF-1α mRNA directs heregulin-inducible expression of a heterologous protein. These data provide a molecular basis for VEGF induction and tumor angiogenesis by heregulin-HER2 signaling and establish a novel mechanism for the regulation of HIF-1α expression.

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Abstract 934: Contributory Role of VEGF Overexpression in Endothelin-1-induced Cardiomyocyte Hypertrophy: Involvement of Hyopoxia Inducible Factor

Circulation ◽

10.1161/circ.116.suppl_16.ii_184-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Nobutake Shimojo ◽

Subrina Jesmin ◽

Yuichi Hattori ◽

Seiji Maeda ◽

Takashi Miyauchi ◽

...

Keyword(s):

Fetal Liver ◽

Hypoxia Inducible Factor ◽

Neonatal Rat ◽

Cardiomyocyte Hypertrophy ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Rat Cardiomyocytes ◽

Endothelin 1 ◽

Vegf Signaling ◽

Endothelial Growth Factor

Although endothelin-1 (ET-1) stimulates vascular endothelial growth factor (VEGF) expression in a variety of cells, including endothelial cells and vascular smooth muscle cells, the effect of ET-1 on expression of VEGF and its receptors in cardiomyocytes is unknown. In the present study, we found that treatment of neonatal rat cardiomyocytes with ET-1 for 24 h resulted in upregulation of VEGF and its two principle receptors, fetal liver kinase (flk)-1 and fms-like tyrosine kinase (flt)-1, in a concentration-dependent manner (10 −12 -10 −6 M). ET-1 treatment also caused significant cardiomyocyte hypertrophy, as indicated by increases in cell surface area (2.0-fold compared to control) and 14 C-leucine uptake (1.8 fold) by cardiomyocytes. And this ET-1 mediated upregulation of VEGF in cardiomyocytes was associated with the induction of hypoxia inducible factor (HIF)-1β and HIF-2α, not HIF-1α. Treatment with TA-0201 (10 −6 M), an ET A selective blocker, eliminated ET-1-induced overexpression of VEGF and its receptors as well as cardiomyocyte hypertrophy. Treatment with VEGF neutralizing peptides (5–10 μg/ml) partially but significantly inhibited ET-1-induced cardiomyocyte hypertrophy. Both TA-0201 and VEGF neutralizing peptides also significantly prevented the increase of phosphorylated KDR, which implies the activation of VEGF system in ET-1 induced hypertrophied cardiomyocyte. These results suggest that ET-1 treatment of cardiomyocytes promotes overexpression of VEGF and its receptors via activation of ET A receptors, and consequently the upregulated VEGF signaling system appears to contribute, at least in part, to ET-1-induced cardiomyocyte hypertrophy.

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Impaired Sphingosine-1-Phosphate Synthesis Induces Preeclampsia by Deactivating Trophoblastic YAP (Yes-Associated Protein) Through S1PR2 (Sphingosine-1-Phosphate Receptor-2)-Induced Actin Polymerizations

Hypertension ◽

10.1161/hypertensionaha.121.18363 ◽

2021 ◽

Author(s):

Jiujiang Liao ◽

Yangxi Zheng ◽

Mingyu Hu ◽

Ping Xu ◽

Li Lin ◽

...

Keyword(s):

Actin Polymerization ◽

Sphingosine Kinase ◽

Actin Dynamics ◽

Extravillous Trophoblast ◽

Trophoblast Invasion ◽

Hippo Signaling ◽

Dependent Manner ◽

Sphingosine Kinase 1 ◽

Sphingosine 1 Phosphate

Incomplete spiral artery remodeling, caused by impaired extravillous trophoblast invasion, is a fundamental pathogenic process associated with malplacentation and the development of preeclampsia. Nevertheless, the mechanisms controlling this regulation of trophoblast invasion are largely unknown. We report that sphingosine-1-phosphate synthesis and expression is abundant in healthy trophoblast, whereas in pregnancies complicated by preeclampsia the placentae are associated with reduced sphingosine-1-phosphate and lower SPHK1 (sphingosine kinase 1) expression and activity. In vivo inhibition of sphingosine kinase 1 activity during placentation in pregnant mice led to decreased placental sphingosine-1-phosphate production and defective placentation, resulting in a preeclampsia phenotype. Moreover, sphingosine-1-phosphate increased HTR8/SVneo (immortalized trophoblast cells) cell invasion in a Hippo-signaling–dependent transcriptional coactivator YAP (Yes-associated protein) dependent manner, which is activated by S1PR2 (sphingosine-1-phosphate receptor-2) and downstream RhoA/ROCK induced actin polymerization. Mutation-based YAP-5SA demonstrated that sphingosine-1-phosphate activation of YAP could be either dependent or independent of Hippo signaling. Together, these findings suggest a novel pathogenic pathway of preeclampsia via disrupted sphingosine-1-phosphate metabolism and signaling-induced, interrupted actin dynamics and YAP deactivation; this may lead to potential novel intervention targets for the prevention and management of preeclampsia.

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