Hypoxia-inducible Factor Gene Research Articles

A hypoxia-derived gene signature to suggest cisplatin-based therapeutic responses in patients with cervical cancer

Cervical cancer remains a significant global public health concern, often exhibits cisplatin resistance in clinical settings. Hypoxia, a characteristic of cervical cancer, substantially contributes to cisplatin resistance. To evaluate the therapeutic efficacy of cisplatin in patients with cervical cancer and to identify potential effective drugs against cisplatin resistance, we established a hypoxia-inducible factor-1 (HIF-1)-related risk score (HRRS) model using clinical data from patients treated with cisplatin. Cox and LASSO regression analyses were used to stratify patient risks and prognosis. Through qRT-PCR, we validated nine potential prognostic HIF-1 genes that successfully predict cisplatin responsiveness in patients and cell lines. Subsequently, we identified fostamatinib, an FDA-approved spleen tyrosine kinase inhibitor, as a promising drug for targeting the HRRS-high group. We observed a positive correlation between the IC50 values of fostamatinib and HRRS in cervical cancer cell lines. Moreover, fostamatinib exhibited potent anticancer effects on high HRRS groups in vitro and in vivo. In summary, we developed a hypoxia-related gene signature that suggests cisplatin response prediction in cervical cancer and identified fostamatinib as a potential novel treatment approach for resistant cases.

Mimicry of microbially-derived butyrate reveals templates for potent intestinal epithelial HIF stabilizers

ABSTRACT Microbiota-derived short-chain fatty acids, including butyrate (BA), have multiple beneficial health effects. In the colon, BA concentrations range from 10 to 20 mM and up to 95% is utilized as energy by the mucosa. BA plays a key role in epithelial-barrier regulation and anti-inflammation, and regulates cell growth and differentiation, at least in part, due to its direct influence on stabilization of the transcription factor hypoxia-inducible factor (HIF). It remains unclear whether BA is the optimal metabolite for such a response. In this study, we explored metabolite mimicry as an attractive strategy for the biological response to HIF. We discovered that 4-mercapto butyrate (MBA) stabilizes HIF more potently and has a longer biological half-life than BA in intestinal epithelial cells (IECs). We validated the MBA-mediated HIF transcriptional activity through the induction of classic HIF gene targets in IECs and enhanced epithelial barrier formation in vitro. In-vivo studies with MBA revealed systemic HIF stabilization in mice, which was more potent than its parent BA metabolite. Mechanistically, we found that MBA enhances oxygen consumption and that the sulfhydryl group is essential for HIF stabilization, but exclusively as a four-carbon SCFA. These findings reveal a combined biochemical mechanism for HIF stabilization and provide a foundation for the discovery of potent metabolite-like scaffolds.

Exploring the Interplay of Hypoxia-Inducible Factors: Unveiling Genetic Connections to Diseases Through Bioinformatics Analysis

Objective: Hypoxia-inducible factor (HIF) is a transcription factor that is effective in the ability of cells to sense and adapt to changes in oxygen levels. HIF1α gene is located in the 14q23.2 chromosome region and consists of 15 exons and 14 introns. It is a transcriptional regulator of metabolic processes such as angiogenesis and erythropoiesis and is required for immunological responses. Material and Methods: Our study examined the function of HIF1α and its relations with other genes and diseases using various bioinformatics database tools. GENEMANIA/GeneCard databases were used to detect the relationship of HIF gene with other genes, miRDB to show target miRNAs, STRING to detect protein-protein interaction, and GWAS databases to show its relationship with diseases. In addition, organs and tissues in which it is expressed were determined using the UniProt database. Results: The bioinformatic analysis yielded significant results, revealing that 189 miRNAs target HIF1α and exhibits close interactions with 10 genes, among which important genes like STAT3, MDM2, TP53, SMAD3, and VHL were identified. The most predominant pathway utilized by the HIF1α gene was determined to be the HIF-1 signaling pathway. A co-expression relationship was also established with proteins EPO, PLIN2, BNIP3, and the enzyme ENO1. Furthermore, it was ascertained that HIF1α exhibits the highest expression levels in the kidney and the perivenous region of the liver. Moreover, close associations have been established between HIF1α and diseases such as renal cell carcinoma and bladder cancer. Conclusion: Identifying the pathways associated with HIF1α, other genes, and epigenetic factors with the help of Bioinformatics Tools may enable experimental studies to be carried out with large cohorts and using a broad perspective. Thus, it may contribute to our understanding of how this gene affects diseases and anomalies and to accelerate the studies of targeted therapeutic treatment.

Precision Medicine in Erythropoietin Deficiency and Treatment Resistance: A Novel Approach to Management of Anaemia in Chronic Kidney Disease.

The study of anaemia is a well-developed discipline where the concepts of precision medicine have, in part, been researched extensively. This review discusses the treatment of erythropoietin (EPO) deficiency anaemia and resistance in cases of chronic kidney disease (CKD). Traditionally, erythropoietin-stimulating agents (ESAs) and iron supplementation have been used to manage anaemia in cases of CKD. However, these treatments pose potential risks, including cardiovascular and thromboembolic events. Newer treatments have emerged to address these risks, such as slow-release and low-dosage intravenous iron, oral iron supplementation, and erythropoietin-iron combination therapy. Another novel approach is the use of hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). This review highlights the need for precision medicine targeting the genetic components of EPO deficiency anaemia in CKD and discusses individual variability in genes such as the erythropoietin gene (EPO), the interleukin-β gene (IL-β), and the hypoxia-inducible factor gene (HIF). Pharmacogenetic testing aims to provide targeted therapies and interventions that are tailored to the specific characteristics of an individual, thus optimising treatment outcomes and minimising resistance and adverse effects. This article concludes by suggesting that receptor modification has the potential to revolutionise the treatment outcomes of patients with erythropoietin deficiency anaemia through the integration of the mentioned approach.

STRUCTURAL MODIFICATIONS OF BUTYRATE REVEAL TEMPLATES FOR INTESTINAL EPITHELIAL HIF STABILIZERS

Microbiota-derived short chain fatty acids, particularly butyrate (BA), show multiple beneficial influences on health. In the colon, BA ranges from 10-20 mM and up to 99% is utilized as a metabolic fuel by the mucosa. BA plays a key role in epithelial barrier regulation, reduces inflammation, and regulates cell growth and differentiation. There are multiple mechanisms by which BA contributes to gut health, many due to its regulatory capacity for gene expression. Our group reported (PMID: 34190032) a direct influence of BA on the stabilization of the transcription factor hypoxia-inducible factor (HIF). It is known that HIF stabilization is essential for appropriate mucosal barrier regulation and the coordination of regenerative capacity in the intestine. However, BA is constantly metabolized limiting its HIF stabilization effect. This observation led to the design and investigation of BA-mimicking compounds that stabilize HIF, but may not be involved in metabolism. We hypothesize that structural modifications of BA yield analogues that stabilize HIF with better efficacy and a longer biological half-life. A library of BA derivatives was screened in search of a non-endogenous analogue with higher potency and/or longer half-life for HIF stabilization. In vitro screenings at physiologically-relevant concentrations (5 mM) were performed using intestinal epithelial cell lines (T84 and CaCO2) in normoxia to determine HIF-1a protein abundance. Various analogues stabilized HIF, with 4-mercapto-butyrate (MBA) being the most promising candidate. The best analogues were validated through the induction of classic HIF gene targets, including BNIP3 and CAIX by q-PCR. MBA exhibited higher induction of these targets compared to BA. Time-course studies revealed that MBA exhibits significantly longer half-life as observed in the stabilization of HIF and induction of gene targets for up to 72 h compared to BA (24 h). Loss of gene induction was observed in MBA treated cells expressing lentiviral shRNA against HIF1b (HIF1b KD), supporting a HIF-dependent transcription. Furthermore, it’s been widely reported that BA enhances epithelial barrier, primarily through HIF coordinated barrier protection. Among several other BA derivatives, MBA enhanced and prolonged epithelial barrier function in intestinal epithelial cells. In vivo studies in C57BL/6 mice explored the induction of HIF targets in tissue and specifically erythropoietin (EPO) in circulation following administration of BA and MBA at similar doses. These studies revealed that induction of EPO with a single dose of MBA exceeded that of native BA. In colonic and kidney tissue, GLUT1 and BNIP3 were moderately induced in vivo. Thus, a non-endogenous BA derivative (MBA) stabilizes HIF at higher potency and longer half-life than native BA and will be used as a template for the development of HIF stabilizing agents.

STRUCTURAL MODIFICATIONS OF BUTYRATE REVEAL TEMPLATES FOR INTESTINAL EPITHELIAL HIF STABILIZERS

Abstract Microbiota-derived short chain fatty acids, particularly butyrate (BA), show multiple beneficial influences on health. In the colon, BA ranges from 10-20 mM and up to 99% is utilized as a metabolic fuel by the mucosa. BA plays a key role in epithelial barrier regulation, reduces inflammation, and regulates cell growth and differentiation. There are multiple mechanisms by which BA contributes to gut health, many due to its regulatory capacity for gene expression. Our group reported (PMID: 34190032) a direct influence of BA on the stabilization of the transcription factor hypoxia-inducible factor (HIF). It is known that HIF stabilization is essential for appropriate mucosal barrier regulation and the coordination of regenerative capacity in the intestine. However, BA is constantly metabolized limiting its HIF stabilization effect. This observation led to the design and investigation of BA-mimicking compounds that stabilize HIF, but may not be involved in metabolism. We hypothesize that structural modifications of BA yield analogues that stabilize HIF with better efficacy and a longer biological half-life. A library of BA derivatives was screened in search of a non-endogenous analogue with higher potency and/or longer half-life for HIF stabilization. In vitro screenings at physiologically-relevant concentrations (5 mM) were performed using intestinal epithelial cell lines (T84 and CaCO2) in normoxia to determine HIF-1a protein abundance. Various analogues stabilized HIF, with 4-mercapto-butyrate (MBA) being the most promising candidate. The best analogues were validated through the induction of classic HIF gene targets, including BNIP3 and CAIX by q-PCR. MBA exhibited higher induction of these targets compared to BA. Time-course studies revealed that MBA exhibits significantly longer half-life as observed in the stabilization of HIF and induction of gene targets for up to 72 h compared to BA (24 h). Loss of gene induction was observed in MBA treated cells expressing lentiviral shRNA against HIF1b (HIF1b KD), supporting a HIF-dependent transcription. Furthermore, it’s been widely reported that BA enhances epithelial barrier, primarily through HIF coordinated barrier protection. Among several other BA derivatives, MBA enhanced and prolonged epithelial barrier function in intestinal epithelial cells. In vivo studies in C57BL/6 mice explored the induction of HIF targets in tissue and specifically erythropoietin (EPO) in circulation following administration of BA and MBA at similar doses. These studies revealed that induction of EPO with a single dose of MBA exceeded that of native BA. In colonic and kidney tissue, GLUT1 and BNIP3 were moderately induced in vivo. Thus, a non-endogenous BA derivative (MBA) stabilizes HIF at higher potency and longer half-life than native BA and will be used as a template for the development of HIF stabilizing agents.

Cobalt Chloride-induced Hypoxia Can Lead SKBR3 and HEK293T Cell Lines toward Epithelial-mesenchymal Transition.

Hypoxia is a common characteristic of the tumor microenvironment. In response to hypoxia, expression of the hypoxia-inducible factor (HIF) can lead to activation of downstream molecular events such as epithelial-mesenchymal transition (EMT), invasion, and angiogenesis. In this study, CoCl2 was used to simulate hypoxia in SKBR3 and HEK293T cell lines to investigate whether this treatment can induce hypoxia-associated EMT and invasion in the studied cells. SKBR3 and HEK293T cells were treated with different concentrations of CoCl2 at different exposure times and their viability was analyzed. To confirm successful hypoxia induction, the expression levels of HIF1α and vascular endothelial growth factor A (VEGFA) mRNA were assessed. Additionally, the expression of EMT-associated markers including snail, E-cadherin, N-cadherin, and vimentin, as well as invasion-related genes including matrix metalloproteinase-2 (MMP2) and MMP9 was measured. We found that cell viability in CoCl2-treated cells was concentration-dependent and was not affected at low doses. While the expression of HIF and VEGFA genes was upregulated following hypoxia induction. E-cadherin expression was significantly downregulated in HEK293T cells; while, N-cadherin and snail were upregulated in both cell lines. Moreover, an increment of MMP expression was only observed in SKBR3 cells. Taken together, the findings indicated that CoCl2 can mimic hypoxia in both cell lines, but EMT was triggered in SKBR3 cells more effectively than in HEK293T cells, and invasion was only stimulated in SKBR3 cells. In conclusion, SKBR3 cancer cells can be used as an EMT model to better understand its control and manipulation mechanisms and to investigate new therapeutic targets for the suppression of tumor metastasis.

Effects of idiopathic erythrocytosis on the left ventricular diastolic functions and the spectrum of genetic mutations: A case control study.

Background:We have aimed at exposing left ventricular diastolic functions and the presence of known genetic mutations for familial erythrocytosis, in patients who exhibit idiopathic erythrocytosis.Methods:Sixty-four patients with idiopathic erythrocytosis (mean age, 46.4 ± 2.7 years) and 30 age-matched healthy subjects were prospectively evaluated. The regions of interest of the erythropoietin receptor, hemoglobin beta-globin, von Hippel-Lindau, hypoxia-inducible factor 2 alpha, and Egl-9 family hypoxia-inducible factor genes were amplified by PCR. Left ventricular (LV) mass was measured by M-mode and 2-dimensional echocardiography. LV diastolic functions were assessed by conventional echocardiography and tissue Doppler imaging.Results:As a result of genetic analyses, genetic mutations for familial erythrocytosis were detected in 5 patients. It has been observed in our study that the risk of cardiovascular disorders is higher in patients. Interventricular septum thickness, left atrial diameter, and some diastolic function parameters such as deceleration time and isovolumetric relaxation time have been found to be significantly higher in idiopathic erythrocytosis group than in the controls.Conclusion:This study has shown that LV diastolic functions were impaired in patients with idiopathic erythrocytosis. In this patient group with increased risk of cardiovascular disorders, the frequent genetic mutations have been detected in 5 patients only. Therefore, further clinical investigations are needed as novel genetic mutations may be discovered in patients with idiopathic erythrocytosis because of cardiovascular risk.

Relative Contributions of Pseudohypoxia and Inflammation to Peritoneal Alterations with Long-Term Peritoneal Dialysis Patients.

Long-term peritoneal dialysis is associated with alterations in peritoneal function, like the development of high small solute transfer rates and impaired ultrafiltration. Also, morphologic changes can develop, the most prominent being loss of mesothelium, vasculopathy, and interstitial fibrosis. Current research suggests peritoneal inflammation as the driving force for these alterations. In this review, the available evidence for inflammation is examined and a new hypothesis is put forward consisting of high glucose-induced pseudohypoxia. Hypoxia of cells is characterized by a high (oxidized-reduced nicotinamide dinucleotide ratio) NADH-NAD+ ratio in their cytosol. Pseudohypoxia is similar but occurs when excessive amounts of glucose are metabolized, as is the case for peritoneal interstitial cells in peritoneal dialysis. The glucose-induced high NADH-NAD+ ratio upregulates the hypoxia-inducible factor-1 gene, which stimulates not only the glucose transporter-1 gene but also many profibrotic genes like TGFβ, vascular endothelial growth factor, plasminogen activator inhibitor-1, and connective tissue growth factor, all known to be involved in the development of peritoneal fibrosis. This review discusses the causes and consequences of pseudohypoxia in peritoneal dialysis and the available options for treatment and prevention. Reducing peritoneal exposure to the excessively high dialysate glucose load is the cornerstone to avoid the pseudohypoxia-induced alterations. This can partly be done by the use of icodextrin or by combinations of low molecular mass osmotic agents, all in a low dose. The addition of alanyl-glutamine to the dialysis solution needs further clinical investigation.

HIF in Gastric Cancer: Regulation and Therapeutic Target.

HIF means hypoxia-inducible factor gene family, and it could regulate various biological processes, including tumor development. In 2021, the FDA approved the new drug Welireg for targeting HIF-2a, and it is mainly used to treat von Hippel-Lindau syndrome, which demonstrated its good prospects in tumor therapy. As the fourth deadliest cancer worldwide, gastric cancer endangers the health of people all across the world. Currently, there are various treatment methods for patients with gastric cancer, but the five-year survival rate of patients with advanced gastric cancer is still not high. Therefore, here we reviewed the regulatory role and target role of HIF in gastric cancer, and provided some references for the treatment of gastric cancer.

Nanodelivery Systems Delivering Hypoxia-Inducible Factor-1 Alpha Short Interfering RNA and Antisense Oligonucleotide for Cancer Treatment

Hypoxia-inducible factor (HIF), which plays a crucial role in oxygen homeostasis, contributes to immunosuppression, tumor angiogenesis, multidrug resistance, photodynamic therapy resistance, and metastasis. HIF as a therapeutic target has attracted scientists’ strong academic research interests. Short interfering RNA (siRNA) and antisense oligonucleotide (ASO) are the more promising and broadly utilized methods for oligonucleotide-based therapy. Their physicochemical characteristics such as hydrophilicity, negative charge, and high molecular weight make them impossible to cross the cell membrane. Moreover, siRNA and ASO are subjected to a rapid deterioration in circulation and cannot translocate into nuclear. Delivery of siRNA and ASO to specific gene targets should be realized without off-target gene silencing and affecting the healthy cells. Nanoparticles as vectors for delivery of siRNA and ASO possess great advantages and flourish in academic research. In this review, we summarized and analyzed regulation mechanisms of HIF under hypoxia, the significant role of HIF in promoting tumor progression, and recent academic research on nanoparticle-based delivery of HIF siRNA and ASO for cancer immunotherapy, antiangiogenesis, reversal of multidrug resistance and radioresistance, potentiating photodynamic therapy, inhibiting tumor metastasis and proliferation, and enhancing apoptosis are reviewed in this thesis. Furthermore, we hope to provide some rewarding suggestions and enlightenments for targeting HIF gene therapy.

The relationship between FOSB and SOCS3 gene polymorphisms and the susceptibility to periodontitis and osteopenia in the Chinese population.

The aim is to analyze the relationship and significance of the FOS, FOSB, Suppressors of cytokine signaling (SOCS), and hypoxia-inducible factor 1 (HIF1) gene loci and their polymorphisms with periodontitis and osteopenia in the Chinese population. In this case-control study, data on questionnaires, periodontal examination, bone mineral density, and FOS, FOSB, SOCS3, and HIF1 gene loci and their polymorphisms were obtained from 474 participants. The data were analyzed using the analysis of variance, Kruskal-Wallis test, χ2 test, and logistic regression. The incidence of osteopenia was significantly increased in patients with periodontitis compared to controls (58.6 vs. 34.4%, P < 0.001). Accordingly, the risk was increased 2.21-fold compared with controls (95% CI 2.09-4.95). Osteopenia patients had a significantly higher risk of periodontitis than patients with normal bone density (OR = 3.22, 95% CI 2.09-4.94). There were significant positive associations between FOSB and SOCS3 polymorphisms and periodontitis and osteopenia susceptibility. Individuals carrying the G/G genotype of the FOSB gene rs708905 locus had an increased risk of periodontitis (OR = 5.06, 95% CI 2.36-10.86) and osteopenia (OR = 3.26, 95% CI 1.34-7.96). Compared with the C/C genotype, the A/A genotype of the FOSB rs8105114 locus was associated with a significantly higher risk of periodontitis (OR = 2.14, 95% CI 1.02-4.53) and osteopenia (OR = 2.85, 95% CI 1.12-7.22). Compared with the A/A genotype, the risk of periodontitis in the G/G genotype of the SOCS3 rs7207782 locus was increased 3.10-fold (P < 0.001), and the risk of osteopenia was increased 2.01-fold (P = 0.023). There was a bidirectional relationship between periodontitis and osteopenia. The rs708905 G/G and rs8105114 A/A genotypes of FOSB and the rs7207782 G/G genotype of SOCS3 were risk factors for both periodontitis and osteopenia in the Chinese population, which could increase knowledge about disease‑specific and cross‑disease genetic pattern.

Butyrate Analogues Mimicking Hypoxia by the Chemical Stabilization of Hypoxia Inducible Factor (HIF)

Short chain fatty acids and specifically butyrate (BA) have been well documented to show multiple beneficial influences on health. Typically, the concentration of colonic butyrate can range from 10‐20 mM and 95‐99% is metabolized into energy by the mucosa. BA plays a key role in epithelial barrier regulation, ameliorates inflammation and regulates cell growth and differentiation. There are multiple mechanisms on how it plays such an important role in gut health, many related to its regulatory capacity for gene expression. Our laboratory recently reported a direct influence of BA on the stabilization of the transcription factor hypoxia‐inducible factor (HIF). BA acts directly and non‐competitively inhibits HIF prolyl hydroxylase 2 (PHD2), responsible for the rapid degradation of HIF in normoxia (NX). However, the efficacy of BA on HIF stabilization is limited due to its rapid metabolism as fuel. Based on these observations, we hypothesize that analogues structurally related to butyrate stabilize HIF with a longer biological half‐life. A small library of BA derivatives was screened in search of a non‐endogenous analogue with higher potency and/or half‐life for HIF stabilization. In vitro screenings at a physiologically‐relevant concentration (5 mM) were performed in intestinal epithelial cell lines T84 and CaCo2 in NX and HIF‐1a ELISA was used to determine protein abundance. Several hits were observed, with 4‐mercapto‐butyrate (SHBA) being the most promising candidate. The best BA analogues were validated through the induction of classic HIF gene targets, including BNIP3 and CaIX by q‐PCR. SHBA exhibited higher induction of these targets compared to BA. Dose response and time‐course studies were performed to compare SHBA and BA. Notably, SHBA exhibits a much longer half‐life as observed in the stabilization of HIF and induction of gene targets at least up to 72 h compared to BA (24 h). In vivo studies in C57BL/6 mice explored the induction of classic HIF targets and specifically erythropoietin (EPO) in circulation following administration of BA and SHBA at similar doses. These studies revealed that induction of EPO with a single dose of SHBA exceeded that of native BA. Thus, a non‐endogenous BA derivative (SHBA) stabilizes HIF at a higher potency and longer half‐life than BA and will be useful as a template for the development of a HIF stabilizing agent.

Screening prolyl hydroxylase domain 2 inhibitory activity of traditional Chinese medicine by CZE-UV.

Prolyl hydroxylase domain 2 (PHD2) is a key enzyme regulating the expression of hypoxia inducible factor (HIF). Its inhibitors can improve the expression of HIF and downstream genes, which can treat hypoxia-related diseases. Therefore, the establishment of a reliable PHD2 inhibitors screening method is of great significance for the drug development of hypoxia-related diseases. In this work, an accurate, rapid, and simple screening method for PHD2 inhibitors was introduced by capillary zone electrophoresis (CZE). In order to improve the detection sensitivity, the derivative reaction of α-ketoglutaric acid (α-OG) and 1,2-diaminobenzene (OPD) was used to enhance the UV absorption of α-OG (the substrate in the enzymatic reaction). The CZE method selected 20mM Na2 B4 O7 buffer (pH9.0) as the separation buffer, +25kV as the separation voltage, 25°Cas the cartridge temperature, and 210nm as the detection wavelength. Under this condition, the analysis of a single sample can be realized within 9min. Compared with the existing reported methods, the present work can directly screen the PHD2 inhibitory activity of traditional Chinese medicine (TCM) extracts, which is of significance for the target-purification of bioactive individual compounds from TCMs. Under the optimal conditions, the PHD2 inhibitor screening platform was successfully established, and it was found that 70% methanol/water extracts of Astragali Radix and Codonopsis pilosula had good PHD2 inhibitory activity. Furthermore, the present work provides a novel approach for screening the PHD2 inhibitory activity of TCM extracts and the discovery of anti-hypoxia bioactive compounds.

High-Altitude Adaptation: Mechanistic Insights from Integrated Genomics and Physiology.

Population genomic analyses of high-altitude humans and other vertebrates have identified numerous candidate genes for hypoxia adaptation, and the physiological pathways implicated by such analyses suggest testable hypotheses about underlying mechanisms. Studies of highland natives that integrate genomic data with experimental measures of physiological performance capacities and subordinate traits are revealing associations between genotypes (e.g., hypoxia-inducible factor gene variants) and hypoxia-responsive phenotypes. The subsequent search for causal mechanisms is complicated by the fact that observed genotypic associations with hypoxia-induced phenotypes may reflect second-order consequences of selection-mediated changes in other (unmeasured) traits that are coupled with the focal trait via feedback regulation. Manipulative experiments to decipher circuits of feedback control and patterns of phenotypic integration can help identify causal relationships that underlie observed genotype–phenotype associations. Such experiments are critical for correct inferences about phenotypic targets of selection and mechanisms of adaptation.

Integrative Analysis Reveals the Landscape of Hypoxia-Inducible Factor (HIF) Family Genes in Pan-Cancer.

Inside the cancer microenvironment, reduced O2 concentration, termed as hypoxia, is a common phenotype and leads to cancer progression. However, little is known about how and when those HIF members are dysregulated in distinct cancers. Here, by integrating a full range of data of thousands of patients, we comprehensively analyzed the genetics, epigenetics, and transcriptomic level of HIF genes and further defined pathways triggered by disrupted hypoxia-inducible factors. We reveal the expression landscape of HIF family genes and further demonstrate that copy number variations underlie such dysregulation. Further analysis indicates that HIF genes associate with cancer hallmarks such as cell cycle and DNA damage response. Drug resistance analysis showed that HIF globally impacts drug effectiveness such as docetaxel. In summary, the overall analysis reveals the landscape of HIF genes in pan-cancer and may assist mechanism research about hypoxia.

Hemocyanin and hexamerinsexpression in response to hypoxia in stoneflies (Plecoptera, Insecta).

Many freshwater ecosystems worldwide undergo hypoxia events that can trigger physiological, behavioral, and molecular responses in many organisms. Among such molecular responses, the regulation of the hemocyanin (Hc) protein expression which plays a major role in oxygen transportation within aquatic insects remains poorly understood. The stoneflies (Plecoptera) are aquatic insects that possess a functional Hc in the hemolymph similar to crustacean that co-occurs with a nonfunctional Hc protein, hexamerins (Hx). However, the role of both proteins during hypoxia remains undetermined. Here, we evaluated the effect of hypoxia on the expression of Hc and Hx proteins via a comparison between hypoxia and normoxia amino acid sequence variation and protein expression pattern within 23 stonefly species. We induced short-term hypoxia in wild-caught stoneflies species, sequenced the target region of Hc and Hx by complementary DNA synthesis, characterized the protein biochemistry using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, ultrafiltration, and polarographic fluorometric method, and amplified the genome region of the hypoxia-inducible factor (HIF) transcriptional response element that regulated Hc using genome walking library approach. We found a lack of Hc expression in all examined species during hypoxia conditions, despite recognition of the HIF gene region as a possible regulatory factor of Hc, suggesting that compensatory responses as metabolic changes or behavioral tracheal movements to enhance respiratory efficiency could be possible mechanics to compensate for hypoxia. A short Hc-like novel isoform was detected instead in these 23 species, possibly due to either protein degradation or alternative splicing mechanisms, suggesting that the protein could be performing a different function other than oxygen transportation. Hx during hypoxia was expressed and exhibited species-level amino acid changes, highlighting a possible role during hypoxia. Our results demonstrate that hypoxia could enable a similar potential adaptive response of multiple species regarding specific physiological requirements, thereby shedding light on community behavior in stress environments that may help us to improve conservation practices and biomonitoring.

Combined therapies with exercise, ozone and mesenchymal stem cells improve the expression of HIF1 and SOX9 in the cartilage tissue of rats with knee osteoarthritis

Knee osteoarthritis (OA) is a common type of degenerative joint disease which decreases the quality of life. Sex-determining region Y box 9 (SOX9) and hypoxia-inducible factor-1 (HIF1) are considered as the key regulators of OA. We investigated the effect of combined therapies with mesenchymal stem cells (MSCs), ozone (O3) and exercise training on SOX9 and HIF1 expression in the cartilage of rats with knee OA. Knee OA was induced by surgical method. OA rats were divided into model, MSCs, ozone, exercise, MSCs + ozone, MSCs + exercise, ozone + exercise and MSCs + ozone + exercise groups. Rats in the MSCs group received intraarticular injection of 1 × 106 cells/kg. Rats in the ozone group received O3 at the concentration of 20 μg/mL, once weekly for 3 weeks. Rats in the exercise group were trained on rodent treadmill three times per week. 48 hours after the programs, cartilage tissues were isolated and the expression of SOX9 and HIF1 was determined using Real-Time PCR. Significant differences were found in the expression of SOX9 and HIF1 between groups (P < 0.0001). Although combined therapies with exercise, MSCs and O3 significantly increased the expression of SOX9 and HIF1 in the cartilage tissue of rats with knee OA, combination of exercise with O3 was significantly more effective compared to the other combined therapies (P < 0.001). Combined therapy with exercise, MSCs and O3 significantly increased the expression of SOX9 and HIF1 genes in the cartilage of rats with knee OA; however, exercise + O3 was significantly more effective.

Analysis of Multiplicity of Hypoxia-Inducible Factors in the Evolution of Triplophysa Fish (Osteichthyes: Nemacheilinae) Reveals Hypoxic Environments Adaptation to Tibetan Plateau.

HIF (Hypoxia-inducible factor) gene family members function as master regulators of cellular and systemic oxygen homeostasis during changes in oxygen availability. Qinghai-Tibet Plateau is a natural laboratory for for long-term hypoxia and cold adaptation. In this context, T. scleroptera that is restricted to >3500 m high-altitude freshwater rivers was selected as the model to compare with a representative species from the plain, P. dabryanus. We cloned different HIF-α and carried out a phylogenetic analysis from invertebrates to vertebrates for identifying HIF-α genes and analyzing their evolutionary history. Intriguingly, the HIF-α has undergone gene duplications might be due to whole-genome duplication (WGD) events during evolution. PAML analysis indicated that HIF-1αA was subjected to positive selection acted on specific sites in Triplophysa lineages. To investigate the relationship between hypoxia adaptation and the regulation of HIF-α stability by pVHL in plateau and plain fish, a series of experiments were carried out. Comparison the luciferase transcriptional activity and protein levels of HIF-αs and the differing interactions of HIF-αs with pVHL, show clear differences between plateau and plain fish. T. scleroptera pVHL could enhance HIF-α transcriptional activity under hypoxia, and functional validation through pVHL protein mutagenesis showed that these mutations increased the stability of HIF-α and its hetero dimerization affinity to ARNT. Our research shows that missense mutations of pVHL induced evolutionary molecular adaptation in Triplophysa fishes living in high altitude hypoxic environments.

Dietary Supplemental Glutamine Enhances the Percentage of Circulating Endothelial Progenitor Cells in Mice with High-Fat Diet-Induced Obesity Subjected to Hind Limb Ischemia.

This study investigated whether glutamine (GLN) pretreatment can enhance circulating endothelial progenitor cells (EPCs) and attenuate inflammatory reaction in high-fat diet-induced obese mice with limb ischemia. Mice were assigned to a normal control (NC), high-fat control (HC), limb ischemia (HI), and GLN limb ischemia (HG) groups. The NC group provided chow diet and treated as a negative control. Mice in the HC and HI groups were fed a high-fat diet which 60% energy provided by fat for 8 weeks. Mice in the HG group were fed the same diet for 4 weeks and then transferred to a high-fat diet with 25% of total protein nitrogen provided as GLN to replace part of the casein for the subsequent 4 weeks. After feeding 8 weeks, mice in the HC group were sham-operated, while the HI and HG groups underwent an operation to induce limb ischemia. All mice except the NC group were euthanized on either day 1 or 7 after the operation. The results showed that the 8 weeks' high-fat diet feeding resulted in obesity. The HG group had higher circulating EPCs on day 1 while muscle vascular endothelial growth factor, matrix metalloproteinase-9, and hypoxia-inducible factor-1 gene expressions were higher on day 7 postischemia than those of the HI group. The superoxide dismutase activity and reduced glutathione content in affected muscles were higher, whereas mRNA expressions of interleukin-6 and tumor necrosis factor-α were lower in the HG than those in the HI group. These findings suggest that obese mice pretreated with GLN-supplemented high-fat diet increased circulating EPC percentage, enhanced the antioxidant capacity, and attenuated inflammatory reactions in response to limb ischemia.