Overexpression Of HIF-1α Research Articles

The promotion of sestrin2/AMPK signaling by HIF-1α overexpression enhances the damage caused by acute myocardial infarction

ObjectiveAcute myocardial infarction (AMI), is a serious form of coronary heart disease. The present study sought to investigate the impact of HIF-1α on AMI, along with its fundamental mechanism.MethodsSprague-Dawley (SD) rats were used to conduct an AMI model. 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) staining was used examine the region of myocardial infract area at various time intervals. Protein expression levels were detected using western blotting. The rats were randomly divided into sham, model, negative control (NC), HIF-1α overexpression (HIF-1α-OE), and HIF-1α-OE+ si-sestrin2 groups. We examined the impact of HIF-1α overexpression on AMI rats using Haematoxylin-Eosin (H&E) staining, TTC staining, enzyme-linked immunosorbent assay (ELISA), TdT-mediated dUTP Nick-End Labeling (TUNEL) assay, and immunohistochemistry (IHC) staining.ResultsAccording to the TTC findings, the region affected by myocardial infarction reached its peak at day 14. Based on the results from the western blot analysis, the levels of HIF-1α and sestrin2 were found the minimum on day 28. Subsequently, we discovered that the overexpression of HIF-1α rescued the cardiac function parameters, improved the morphology of myocardial tissue, and mitigated inflammation. Furthermore, the overexpression of HIF-1α led to a reduction in the levels of MDA and an increase in the levels of SOD. Moreover, the overexpression of HIF-1α resulted in a decrease in cellular apoptosis. This result was confirmed by the expression levels of Bcl-2 and Bax. Nevertheless, the defensive impact of elevated HIF-1α expression was somewhat counteracted by the suppression of sestrin2. In terms of mechanism, the overexpression of HIF-1α enhanced the levels of sestrin2 and the protein adenosine monophosphate activated kinase (AMPK).ConclusionOur research suggests that the overexpression of HIF-1α may rescue the damage to myocardial tissue, and this effect is associated with the sestrin2/AMPK signaling pathway. Our study provides a novel comprehension of the protective effects of HIF-1α overexpression on AMI.

CSIG-22. CAMKIIΓ INTERACTS WITH HIF-1Α IN AN OXYGEN-INDEPENDENT MANNER TO DRIVE PLASTICITY IN GLIOBLASTOMA

Abstract Glioblastoma (GBM) is a highly aggressive brain tumor that demonstrates treatment resistance. Hypoxia-inducible factor 1-alpha (HIF-1α) plays a crucial role in GBM progression and recurrence. While HIF-1α overexpression is correlated with poor GBM survival, clinical inhibitors have shown limited efficacy due to compensatory pathways that are not well understood. In previous studies, we discovered GBM upregulates HIF-1α after temozolomide (TMZ) through an unknown mechanism independent of physiological hypoxia. We demonstrated HIF-1α but not HIF-2α knockdown reduces the stem-like properties of GBM and enhances their sensitivity to TMZ therapy in vitro and in vivo. To elucidate the mechanism of TMZ-induced HIF-1α stabilization, we performed co-immunoprecipitation of HIF-1α followed by mass spectrometry analysis (IP-MS). Our findings revealed 99 binding partners that were significantly and uniquely upregulated after TMZ treatment compared to GBM cells cultured under normal oxygen tension (20% O2), hypoxia (1% O2), or DMSO. Among these interactions, we focused on the HIF-1α-CAMKIIγ axis for further investigation based on pathway enrichment, patient survival data, and co-expression analysis in the TCGA_GBM dataset. Co-immunoprecipitation experiments confirmed enhanced binding between HIF-1α and CAMKIIγ in different GBM patient-derived xenograft (PDX) lines while this interaction was significantly reduced in normal astrocytes. Knockdown of CAMKIIγ inhibited the transcriptional activity of HIF-1α, increased its protein turnover, and improved TMZ sensitivity compared to control cells following TMZ treatment. Additionally, the expression of stem-cell markers and neurosphere formation, which are associated with GBM aggressiveness, were attenuated in hypoxia and TMZ conditions when CAMKIIγ was absent. Our data demonstrated that the HIF-1α-CAMKIIγ axis is critical for TMZ-induction of HIF signaling and cellular plasticity.

Unveiling the role of hypoxic macrophage-derived exosomes in driving colorectal cancer progression.

The crosstalk between tumor cells and macrophages under hypoxic conditions has been acknowledged as a pivotal determinant in the progression of colorectal cancer (CRC). Previous research has underscored the significance of exosomes derived from hypoxic tumor cells in facilitating tumor progression through inducing the polarization of macrophages towards the M2-like phenotype. The precise influence of hypoxic macrophage-derived exosomes (HMDEs) on the progression of CRC has not yet been fully elucidated. The objective of this study was to investigate the role of HMDEs in the progression of CRC. We discovered that there was an elevated release of exosomes derived from macrophages in hypoxic conditions. Additionally, the hypoxia-induced macrophage-derived exosomes played a crucial role in promoting the progression of CRC. We have also demonstrated that HMDEs have the ability to induce cell cycle transition and inhibit cell apoptosis, thereby promoting the growth of CRC cells. Furthermore, the underlying molecular mechanisms of these effects have been identified. The overexpression of Hif-1α results in its direct interaction with distinct regions (-521- -516 bp and -401- -391 bp) of the Hsp90 promoter during hypoxic circumstances. This binding event led to the overexpression of Hsp90 and the subsequent elevation of Hsp90 protein levels within HMDEs. Importantly, the crucial interaction between Hsp90 and Lats1 resulted in the deactivation of Lats1 and the inhibition of Yap phosphorylation. Ultimately, this series of events lead to the deactivation of the Hippo signaling pathway. Our in vivo and in vitro studies presented compelling evidence for the crucial role of hypoxic macrophage-derived exosomal Hsp90 in promoting CRC progression through the inhibition of the Hippo signaling pathway. These findings represented a significant advancement in our comprehension of the complex interplay between macrophages and CRC cells under hypoxic conditions.

Daprodustat, a Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitor, Improves Hematological Insufficiency without Progression of Myelodysplastic Syndrome with Chronic Kidney Disease

Introduction Hematological insufficiency is a critical issue in the treatment of myelodysplastic syndrome (MDS). The current standard treatment for cytopenia in MDS involves blood transfusion and the administration of erythropoiesis stimulating agents (ESAs). However, ESAs are only effective in certain patients with low erythropoietin levels; patients who are not suitable candidates for allogeneic hematopoietic stem cell transplantation (allo-HSCT) require lifelong blood transfusions. As a result, there is a growing demand for new treatments for cytopenia in MDS, and researchers have been exploring various molecular-targeted drugs in recent years. One promising option is the hypoxia-inducible factor -prolyl hydroxylase inhibitor (HIF-PHi). This inhibitor stabilizes HIF1α, which in turn normalizes endogenous erythropoietin production and iron metabolism, leading to improved renal anemia. It is believed that HIF-PHi could potentially enhance MDS-related anemia by increasing erythropoietin levels. However, despite some case reports, there have been no comprehensive clinical studies evaluating the effectiveness and safety of HIF-PH inhibitors for MDS. Moreover, it is essential to address concerns related to HIF1α overexpression, which has been associated with exacerbating various malignant tumors, including MDS. To assess the safety and effectiveness of HIF-PHi for MDS, we conducted a prospective clinical trial evaluating an oral HIF-PHi called daprodustat. Methods The study included MDS patients with chronic kidney disease (CKD) stage ≥ 3, considering daprodustat's approval in Japan, at Ebina General Hospital. Patients with MDS who were treated with deoxyribonucleic acid methylation inhibitors and/or who underwent allo-HSCT were excluded. Participants were administered daprodustat at the approved dose for renal anemia and underwent regular blood sampling and bone marrow examination. The primary and secondary endpoints were the leukemia rate within 1 year after HIF-PHi administration and hematological improvement (HI), respectively. The study was conducted in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and was approved by the Institutional Review Board of the Ebina General Hospital (approval number: JMA-388). Written informed consent was obtained from all participants. Results Seventeen patients with MDS, with a median age of 81years, were included in the analysis. Revised International Prognostic Scoring System scores (IPSS-R) were very low, low, intermediate, high, and very high in 1, 11, 3, 1, and 1 patients, respectively. Five cases were changed from ESA treatment. Within 1 year after HIF-PHi administration, no patients developed leukemia, and both peripheral blood Wilms tumor 1 protein concentrations and bone marrow myeloblast counts remained unchanged from pre-treatment levels. HI was observed in 8 patients within 6 months, and the median dose was 6 (range, 2-12) mg for HI achievement. On univariate analysis, pretreatment transferrin saturation (TSAT, P = 0.002, Figure 1) and ferritin concentration ( P = 0.016) were inversely associated with HI achievement. However, pretreatment hepcidin concentration, erythropoietin concentration, previous ESA use, and IPSS-R were not associated with HI achievement. Notably, when a TSAT cutoff of < 45% was used, achieving HI showed a sensitivity and specificity of 87.5% and 100.0%. Moreover, patients with TSAT < 45% showed significant improvement in anemia after 3 months and beyond (Figure 2). No significant differences were observed in neutrophil and platelet counts between the two groups. Throughout the study, eleven adverse events occurred, including 6 infections, and 1 case each of myocardial infarction, eosinophilia, erythema multiforme, organizing pneumonia, and spinal fracture. Conclusion HIF-PHi administration did not lead to MDS progression. Notably, in MDS patients with CKD, low TSAT was a predictor for achieving HI by HIF-PHi.

Hypoxia and HIF-1α promote lytic de novo KSHV infection.

The current view is that the default pathway of Kaposi's sarcoma-associated herpesvirus (KSHV) infection is the establishment of latency, which is a prerequisite for lifelong infection and viral oncogenesis. This view about KSHV infection is supported by the observations that KSHV latently infects most of the cell lines cultured in vitro in the absence of any environmental stresses that may occur in vivo. The goal of this study was to determine the effect of hypoxia, a natural stress stimulus, on primary KSHV infection. Our data indicate that hypoxia promotes euchromatin formation on the KSHV genome following infection and supports lytic de novo KSHV infection. We also discovered that hypoxia-inducible factor-1α is required and sufficient for allowing lytic KSHV infection. Based on our results, we propose that hypoxia promotes lytic de novo infection in cells that otherwise support latent infection under normoxia; that is, the environmental conditions can determine the outcome of KSHV primary infection.

Association of hypoxia-inducible factor 1α expression with susceptibility to hepatitis B virus-related hepatocellular carcinoma: A meta-analysis.

Hypoxia-inducible factor 1α (HIF-1α) triggers tumorigenesis and progression in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Inconsistent findings have been reported on the influence of HIF-1α over-expression on the clinical outcomes of HBV-related HCC. This study aims to clarify the role of HIF-1α overexpression in the tumorigenesis and prognosis of HBV-induced HCC. Systematic and comprehensive search of online papers was carried out to elucidate the contribution of HIF-1α expression to susceptibility of HBV-induced HCC. STATA 12.0 software was utilized to analyze available data extracted from all eligible literature. Publication bias and sensitivity were comprehensively analyzed. A total of 23 published studies involving 2244 subjects were finally screened. The HIF-1α expression was remarkably upregulated in HBV-induced HCC tissues than in normal liver tissues, non-tumorous tissues, paraneoplastic tissues, and non-HBV HCC tissues. The high HIF-1α expression tended to be positively related to capsular infiltration (odds ratio (OR) 1.767; 95% confidence interval (CI) 1.058, 2.950). The HIF-1α expression was relevant to lymph node metastasis (OR 3.778; 95% CI 1.666, 8.568). High levels of HIF-1α expression tended to be closely implicated in portal vein invasion (OR 6.728, 95% CI 2.191, 20.656) but were irrelevant to alpha-fetoprotein, cirrhosis, Edmondson grading, tumor size, age, gender, and histological grade. Analysis of pooled data showed that HIF-1α was not statistically relevant to poor overall survival in HBV-related HCC. Our data provides compelling evidence that HIF-1α overexpression may imply a greater probability of invasion and metastasis in patients with HBV-induced HCC.

The mechanism and targeted intervention of the HIF-1 pathway in improving atherosclerotic heart's sensitivity to ischemic postconditioning

BackgroundIPoC possesses a preventive effect against IR injury in healthy myocardium, but IPoC's protective effect on atherosclerotic myocardium is controversial. The current investigation aims to determine whether IPoC remains protective in atherosclerotic myocardium subjected to ischemia-reperfusion (IR) injury; to explore the specific mechanisms by which IPoC exerts cardioprotection; to explore whether HIF-1 upregulation combined with IPoC could further the provide cardioprotection; and to gaze at the specific mechanism whereby combined treatment expert the cardioprotection. MethodsApoE−/− mice fed with a high-fat diet (HFD) were used to develop a model of atherosclerosis. The myocardial IR model was induced by occlusion of the left anterior descending (LAD) artery for 45 min, followed by reperfusion for 120 min. The protection of IPoC in both healthy and atherosclerotic myocardium was evaluated by measuring oxidative stress, apoptosis, infarct size, pathology, mitochondrial dysfunction and morphology of myocardium. The specific mechanism by which IPoC exerts cardioprotection in healthy and atherosclerotic myocardium was observed by measuring the expression of proteins involved in HIF-1, APMK and RISK pathways. The effect of HIF-1α overexpression on the cardioprotection by IPoC was observed by intravenous AAV9 -HIF-1α injection. ResultsIn healthy ischemic myocardium, IPoC exerted myocardial protective effects (antioxidant, anti-apoptosis, and improved mitochondrial function) through the activation of HIF-1, AMPK and RISK pathways. In atherosclerotic ischemic myocardium, IPoC exerted cardioprotection only through the activation of HIF-1 pathway; however, HIF-1 overexpression combined IPoC restored the activation of AMPK and RISK pathways, thereby further alleviating the myocardial IR injury. ConclusionsIn the atherosclerotic state, the HIF-1 pathway is the intrinsic mechanism by which IPoC exerts cardioprotective effects. The combination of HIF-1 upregulation and IPoC has a significant effect in reducing myocardial injury, which is worth being promoted and advocated. In addition, HIF-1-AMPK and HIF-1-RISK may be two endogenous cardioprotective signalling pathways with great value, which deserve to be thoroughly investigated in the future.

HIF-1α-induced upregulation of m6A reader IGF2BP1 facilitates peripheral nerve injury recovery by enhancing SLC7A11 mRNA stabilization.

The recovery of peripheral nerve injury (PNI) is not ideal in clinic. Our previous study revealed that hypoxia treatment promoted PNI repair by inhibiting ferroptosis. The aim of this study was to investigate the underlying molecular mechanism of HIF-1α in hypoxia-PNI recovery. M6A dot blot was used to determine the total level of m6A modification. Besides, HIF-1α small interfering RNA (siRNA) or IGF2BP1 overexpression vector was transfected into dorsal root ganglion (DRG) neurons to alter the expression of HIF-1α and IGF2BP1. Subsequently, MeRIP-PCR analysis was applied to validate the m6A methylation level of SLC7A11. We demonstrated the hypoxia stimulated HIF-1α-dependent expression of IGF2BP1 and promoted the overall m6A methylation levels of DRG neurons. Overexpression of HIF-1α increased the expressions of neurotrophic factors including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial-derived neurotrophic factor (GDNF), which could be effectively reversed by siRNA knockdown of IGF2BP1. Moreover, upregulation of HIF-1α contributed to the m6A methylation level and mRNA stabilization of SLC7A11. This study revealed that the HIF-1α/IGF2BP1/SLC7A11 regulatory axis facilitated the recovery of injured DRG neurons. Our findings suggest a novel insight for the m6A methylation modification in PNI recovery.

The association of Hypoxia-Inducible Factor-2α (HIF-2α) overexpression score with Germinal Center B-Cell Like (GCB) and Non-Germinal Center B-Cell Like (Non-GCB) subtypes of Diffuse Large B-cell Lymphoma (DLBCL)

Link of Video Abstract: https://www.youtube.com/watch?v=KF58IGGdWmc Background: Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma. It is classified into homogeneous subtypes, namely Germinal Center B-Cell Like (GCB) and Non-Germinal Center B-Cell Like (GCB), with the latter associated with worse survival outcomes. Increased expression of Hypoxia-Inducible Factor-2α (HIF-2α) is often observed in DLBCL and has been correlated with enhanced angiogenesis, suggesting its potential as a prognostic factor in managing DLBCL. The study evaluates the association between HIF-2α overexpression and the GCB and non-GCB subtypes of DLBCL. Methods: This cross-sectional study utilized samples from DLBCL patients at Dr. Kariadi Semarang Hospital between January and December 2021. Immunohistochemistry was performed on the samples to determine the DLBCL subtypes and assess the presence of HIF-2α. HIF-2α was evaluated by immunohistochemistry based on its distribution and intensity. The Kruskal-Wallis test was used to find the association between HIF-2α expression and the GCB and non-GCB subtypes of DLBCL. Furthermore, Spearman's rank correlation test explored the correlation between all numeric variables. Results: A total of 30 subjects were included in this study, with 7 samples of GCB subtype (23.3%) and 23 samples of non-GCB subtype (76.6%). Kruskal-Wallis test showed no association between HIF-2α expression and the subtypes of DLBCL (p=0.812). Spearman's rho correlation test indicated no correlation between HIF-2α overexpression score with NCCN IPI score in GCB (r=0.219; p=0.637) and non-GCB (r=-0.194; p=0.386). Conclusion: There was no association between HIF-2α expression and GCB and non-GCB subtypes of DLBCL. Additionally, no correlation was found between HIF-2α overexpression and NCCN IPI score.

Allicin, an Emerging Treatment for Pulmonary Arterial Hypertension: An Experimental Study.

We assessed whether allicin, through its antihypertensive and antioxidant effects, relieves vascular remodeling, endothelial function, and oxidative stress (OS), thereby improving experimental pulmonary arterial hypertension (PAH). Allicin (16 mg/kg) was administered to rats with PAH (monocrotaline 60 mg/kg). Allicin encouraged body weight gain and survival rate, and medial wall thickness and the right ventricle (RV) hypertrophy were prevented. Also, angiotensin II concentrations in the lung (0.37 ± 0.01 vs. 0.47 ± 0.06 pmoles/mL, allicin and control, respectively) and plasma (0.57 ± 0.05 vs. 0.75 ± 0.064, allicin and control respectively) and the expressions of angiotensin-converting enzyme II and angiotensin II type 1 receptor in lung tissue were maintained at normal control levels with allicin. In PAH rats treated with allicin, nitric oxide (NO) (31.72 ± 1.22 and 51.4 ± 3.45 pmoles/mL), tetrahydrobiopterin (8.43 ± 0.33 and 10.14 ± 0.70 pmoles/mL), cyclic guanosine monophosphate (5.54 ± 0.42 and 5.64 ± 0.73 pmoles/mL), and Ang-(1-7) (0.88 ± 0.23 and 0.83 ± 0.056 pmoles/mL) concentrations increased in lung tissue and plasma, respectively. In contrast, dihydrobiopterin increase was prevented in both lung tissue and plasma (5.75 ± 0.3 and 5.64 ± 0.73 pmoles/mL); meanwhile, phosphodiesterase-5 was maintained at normal levels in lung tissue. OS in PAH was prevented with allicin through the increased expression of Nrf2 in the lung. Allicin prevented the lung response to hypoxia, preventing the overexpression of HIF-1α and VEGF. Allicin attenuated the vascular remodeling and RV hypertrophy in PAH through its effects on NO-dependent vasodilation, modulation of RAS, and amelioration of OS. Also, these effects could be associated with the modulation of HIF-1α and improved lung oxygenation. The global effects of allicin contribute to preventing endothelial dysfunction, remodeling of the pulmonary arteries, and RV hypertrophy, preventing heart failure, thus favoring survival. Although human studies are needed, the data suggest that, alone or in combination therapy, allicin may be an alternative in treating PAH if we consider that, similarly to current treatments, it improves lung vasodilation and increase survival. Allicin may be considered an option when there is a lack of efficacy, and where drug intolerance is observed, to enhance the efficacy of drugs, or when more than one pathogenic mechanism must be addressed.

Dapagliflozin Alleviates Diabetic Kidney Disease via Hypoxia Inducible Factor 1α/Heme Oxygenase 1-Mediated Ferroptosis.

Aims: Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) showed excellent renoprotective effects; however, the underlying mechanism remains not fully understood. Previous studies have revealed the importance of ferroptosis, which is closely related to oxidative stress, in the progression of DKD. In the current study, we hypothesized that SGLT2i could relieve ferroptosis and thereby alleviate renal injury in DKD due to their antioxidative stress effects. Results: Typical changes of ferroptosis including massive lipid peroxidation, compromised antioxidant capability, and iron overload were found in db/db mice and high glucose/high fat (HG/HF)-treated HK-2 cells. Furthermore, increased expression of hypoxia inducible factor 1α (HIF1α) and heme oxygenase 1 (HO1) was observed in db/db mice and HG/HF-treated HK-2 cells as well. Dapagliflozin treatment significantly ameliorated the ferroptosis-related changes via attenuating overactivation of the HIF1α/HO1 axis in vivo and in vitro. Besides, downregulation of the HIF1α/HO1 axis alleviated ferroptosis, while overexpression of HIF1α and HO1 aggravated ferroptosis induced by HG/HF in HK-2 cells. Innovation and Conclusion: This study revealed that SGLT2i played a renoprotective role in DKD, at least in part, through alleviating HIF1α/HO1-mediated ferroptosis. Antioxid. Redox Signal. 40, 492-509.

Impairment of HIF-2α Expression Induced the Compensatory Overexpression of the HIF-1α/SDF-1 Axis to Promote Wound Healing.

Glucocorticoids are common anti-inflammatory factors; however, they have been reported to have side effects that delay the wound healing process. In a previous study, we found that mesenchymal stem cells isolated from the adipose tissue of patients with long-term glucocorticoid treatment (sAT-MSC) showed impaired wound healing ability due to the downregulation of SDF-1. In this study, we aimed to clarify the mechanisms by which SDF-1 is regulated in sAT-MSC by focusing on the roles of hypoxia-inducible factors (HIFs). Our data suggested that sAT-MSC showed impairment of HIF-1α and the upregulation of HIF-2α. Notably, HIF-2α impairment resulted in the compensatory overexpression of HIF-1α and its target gene SDF-1, which improved the wound healing ability of sAT-MSC. In addition, using knockdown/knockout heterozygous HIF-2α kd/null mice (kd/null), the functions of HIF-2α in the ischemic wound healing process were clarified. With a 50% reduction in the expression of HIF-2α, kd/null mice showed significantly induced wound healing effects, which are involved in the promotion of the inflammatory phase. Specifically, kd/null mice showed the compensatory overexpression of HIF-1α, which upregulated the expression of SDF-1 and enhanced the recruitment of inflammatory cells, such as neutrophils. Our study highlighted the novel function of HIF-2α in the inflammation phase of the wound healing process through the HIF-1α/SDF-1 axis, suggesting that the physiological state of the impaired expression of HIF-2α is a new concept for wound therapy.

HIF-1α increases the osteogenic capacity of ADSCs by coupling angiogenesis and osteogenesis via the HIF-1α/VEGF/AKT/mTOR signaling pathway

BackgroundStabilization and increased activity of hypoxia-inducible factor 1-α (HIF-1α) can directly increase cancellous bone formation and play an essential role in bone modeling and remodeling. However, whether an increased HIF-1α expression in adipose-derived stem cells (ADSCs) increases osteogenic capacity and promotes bone regeneration is not known.ResultsIn this study, ADSCs transfected with small interfering RNA and HIF-1α overexpression plasmid were established to investigate the proliferation, migration, adhesion, and osteogenic capacity of ADSCs and the angiogenic ability of human umbilical vein endothelial cells (HUVECs). Overexpression of HIF-1α could promote the biological functions of ADSCs, and the angiogenic ability of HUVECs. Western blotting showed that the protein levels of osteogenesis-related factors were increased when HIF-1α was overexpressed. Furthermore, the influence of upregulation of HIF-1α in ADSC sheets on osseointegration was evaluated using a Sprague–Dawley (SD) rats implant model, in which the bone mass and osteoid mineralization speed were evaluated by radiological and histological analysis. The overexpression of HIF-1α in ADSCs enhanced bone remodeling and osseointegration around titanium implants. However, transfecting the small interfering RNA (siRNA) of HIF-1α in ADSCs attenuated their osteogenic and angiogenic capacity. Finally, it was confirmed in vitro that HIF-1α promotes osteogenic differentiation and the biological functions in ADSCs via the VEGF/AKT/mTOR pathway.ConclusionsThis study demonstrates that HIF-1α has a critical ability to promote osteogenic differentiation in ADSCs by coupling osteogenesis and angiogenesis via the VEGF/AKT/mTOR signaling pathway, which in turn increases osteointegration and bone formation around titanium implants.Graphical

Overexpression of SENP3 promotes PPAR-γ transcription through the increase of HIF-1α stability via SUMO2/3 and participates in molecular mechanisms of osteoporosis

Patients with type II diabetes are exposed to a high risk of osteoporosis. The present study sought to exploit the detailed mechanisms of the SENP3/HIF-1α/PPAR-γ axis in osteoporosis. A rat model of type II diabetic osteoporosis was established, followed by the isolation of bone marrow mononuclear macrophages (BMMs). Gain- and loss-of-function assays were conducted in rat models and BMMs from rat models, followed by the evaluation of SENP3, HIF-1α, and PPAR-γ expression and detection of osteoclast differentiation-related indexes. Next, the SUMOylated modification of HIF-1α and the regulation of SENP3 on SUMOylated modification level of HIF-1α were assessed using immunoprecipitation, and the binding of HIF-1α to the PPARγ promoter was identified with ChIP and dual-luciferase reporter assays. SENP3 and HIF-1α expression was down-regulated in tissues of type II diabetes-induced osteoporotic rats and BMMs, with high SUMOylated modification levels of HIF-1α. Mechanically, HIF-1α was modified by SUMO2/3. SENP3 suppressed SUMOylated modification of HIF-1α and enhanced HIF-1α stability. HIF-1α bound to the PPAR-γ promoter and facilitated PPAR-γ transcription. SENP3 overexpression restrained osteoblast differentiation in type II diabetes-induced osteoporotic rats and BMMs from rat models. SENP3 knockdown facilitated osteoclast differentiation in type II diabetes-induced osteoporotic rats and BMMs from rat models, which was neutralized by further HIF-1α overexpression. To sum up, SENP3 overexpression restrained osteoclast differentiation in type II diabetic osteoporosis by increasing HIF-1α stability and expression and thus promoting PPAR-γ expression via de-SUMOylation, which might expand the understanding of the mechanisms of type II diabetes combined with osteoporosis.

The role and regulatory mechanism of HIF-1α in myocardial injury in rats undergoing cardiopulmonary bypass

Background Hypoxia-inducible factor-1alpha (HIF-1α) is a transcription factor implicated in physiological and pathological responses to hypoxia. The present study aims to investigate the effect and mechanism of HIF-1α on cardiopulmonary bypass (CPB)-related myocardial injury, thereby conferring a theoretical basis for the clinical treatment of myocardial injury in CPB. Methods An experimental model of CPB was established in rats by surgery. Adenovirus-packaged overexpression vectors and antiagomiRNA were used to overexpress HIF-1α and NR4A1 or inhibit miR-124-3p expression in rat myocardial tissues, respectively. qRT-PCR and Western blot detected HIF-1α, miR-124-3p, and NR4A1 expression in myocardial tissues. The rat cardiac function was monitored through an echocardiogram. The rat plasma at different stages of CPB was collected, followed by the detection of IL-6, cTnT, CK-MB, and IL-1β. TUNEL staining measured apoptosis in myocardial tissues. ChIP assay analysed the enrichment of HIF-1α on the miR-124-3p promoter. The binding relationships between HIF-1α and miR-124-3p promoter sequence and between miR-124-3p and NR4A1 3'UTR sequence were confirmed by dual-luciferase reporter assay. Results HIF-1α expression had no significant change after CPB modelling. Overexpression of HIF-1α improved the cardiac function of CPB rats, decreased plasma IL-6, cTnT, CK-MB, and IL-1β levels, and reduced TUNEL-positive myocardial cells. HIF-1α was enriched on the miR-124-3p promoter and promoted miR-124-3p expression. miR-124-3p bound to NR4A1 3'UTR sequence and targeted NR4A1 expression. Inhibition of miR-124-3p or overexpression of NR4A1 partially reversed the ameliorative effect of HIF-1α overexpression on myocardial injury in CPB rats. Conclusion Overexpression of HIF-1α can improve myocardial injury in CPB rats via the miR-124-3p/NR4A1 axis.

Regulation of Long Noncoding RNA NEAT1/miR-320a/HIF-1α Competitive Endogenous RNA Regulatory Network in Diabetic Retinopathy.

To determine the mechanism that long noncoding RNA NEAT1 (lncNEAT1)/miR-320a competitive endogenous RNA (ceRNA) network regulates hypoxia-inducible factor-1α (HIF-1α) in ARPE-19 cells and its potential role in diabetic retinopathy (DR). ARPE-19 cells were cultured in a normal or high-glucose (HG) medium, and cell migration, invasion, and permeability were detected by scratch, transwell, and FITC-dextran staining assays. LncNEAT1, HIF-1α, ZO-1, occludin, N-cadherin, and vimentin levels were tested. The binding of lncNEAT1 to miR-320a was verified by dual-luciferase reporter assay, and the binding of miR-320a to HIF-1α by RIP assay. ARPE-19 cells were treated with lncNEAT1 or HIF-1α shRNA or miR-320a agomir to determine the activation of ANGPTL4/p-STAT3 pathway. The effect of lncNEAT1 in DR and its regulations on miR-320a and HIF-1α were determined in a rat model of DR. HG treatment promoted the migration, invasion, and permeability of ARPE-19 cells. After lncNEAT1 silencing, HIF-1α, N-cadherin, and vimentin levels were downregulated, ZO-1 and occludin levels were upregulated, and the migration, permeability, and invasion of HG-treated ARPE-19 cells were inhibited. However, HIF-1α overexpression increased N-cadherin and vimentin expression, reduced ZO-1 and occludin expression, and promoted the migration, permeability, and invasion of ARPE-19 cells. The binding of miR-320a with both lncNEAT1 and HIF-1α was predicted and confirmed. In a diabetic rat model, silencing lncNEAT1 inhibited HIF-1α/ANGPTL4/p-STAT3 pathway activation and alleviated retinopathy. The lncNETA1/miR-320a/HIF-1α ceRNA network activates the ANGPTL4/p-STAT3 pathway and promotes HG-induced ARPE-19 cell invasion and migration.

LncRNA CDKN2B-AS1 interacts with LIN28B to exacerbate sepsis-induced acute lung injury by inducing HIF-1α/NLRP3-mediated pyroptosis.

Sepsis-associated acute lung injury (ALI) is a life-threatening condition in intensive care units with high mortality. LncRNAs have been confirmed to participate in the underlying pathogenesis of septic ALI. This study investigated the biological functions of lncRNA CDKN2B-AS1 in septic ALI and its potential mechanism.BEAS-2B cells were challenged with lipopolysaccharide (LPS) and mice were subjected to caecal ligation and puncture (CLP) to induce septic ALI in vitro and in vivo. The expression levels of CDKN2B-AS1, LIN28B, HIF-1α, and pyroptosis-related molecules were assessed by qRT-PCR or Western blotting. The production of IL-1β and IL-18 was detected by ELISA. BEAS-2B cell pyroptosis was examined by flow cytometry. The interaction between LIN28B and CDKN2B-AS1/HIF-1α was validated by RIP and RNA pull-down assays. Colocalization of CDKN2B-AS1 and LIN28B was observed by FISH. ALI was determined by HE staining, the lung wet-to-dry (W/D) weight ratio, inflammatory cell numbers, and total protein concentration in bronchoalveolar lavage fluid (BALF). Caspase-1 expression in the lung tissues was examined by immunohistochemical staining.CDKN2B-AS1 was upregulated in BEAS-2B cells after LPS stimulation. CDKN2B-AS1 knockdown inhibited pyroptosis in LPS-exposed BEAS-2B cells in vitro and the lung tissues of septic mice in vivo. Mechanistically, CDKN2B-AS1 interacted with LIN28B to enhance HIF-1α stability. Rescue experiments showed that HIF-1α overexpression counteracted the inhibitory effect of sh-CDKN2B-AS1 on LPS-induced pyroptosis. CDKN2B-AS1 bound to LIN28B to trigger NLRP3-mediated pyroptosis by stabilizing HIF-1α, which promoted sepsis-induced ALI. CDKN2B-AS1 might be a novel therapeutic target for this disease.

Thymoquinone affects the gemcitabine sensitivity of pancreatic cancer by regulating collagen via hypoxia inducible factor-1α.

Objective: To clarify the potential therapeutic effects of thymoquinone (TQ) on pancreatic cancer and its gemcitabine (GEM) sensitivity. Methods: The expression levels of hypoxia inducible factor-1α (HIF-1α), collagens (COL1A1, COL3A1, and COL5A1), and transforming growth factor-β1 (TGFβ1) in pancreatic cancer and para-carcinoma tissues were compared using immunohistochemical methods, and their relationships with TNM staging were analyzed. The effects of TQ on apoptosis, migration, invasion, and GEM sensitivity of pancreatic cancer cells were assessed using in vitro and in vivo experiments. Western blot and immunohistochemistry were used to detect the expression levels of HIF-1α, extracellular matrix (ECM) production pathway-related proteins, and TGFβ/Smad signaling pathway-related proteins. Results: The expression levels of HIF-1α, COL1A1, COL3A1, COL5A1, and TGFβ1 in pancreatic cancer tissues were significantly higher than those in para-carcinoma tissues and correlated with TNM staging (p < 0.05). TQ and GEM administration inhibited the migration and invasion of the human pancreatic cancer cell line PANC-1 and promoted the apoptosis of PANC-1 cells. The combination of TQ and GEM was more effective than GEM alone. Western blot analysis showed that the expression levels of HIF-1α, ECM production pathway-related proteins, and TGFβ/Smad signaling pathway-related proteins were significantly decreased when TQ was used to treat PANC-1 cells (p < 0.05), and the expression levels of these proteins in the TQ + GEM group were significantly more decreased than those in the GEM group. Overexpression or knockdown of HIF-1α in PANC-1 cells showed the same effects as those induced by TQ administration. In vivo experiments showed that in PANC-1 tumor-bearing mice, tumor volume and tumor weight in mice treated with GEM and TQ were significantly lower than those in control or GEM-treated mice, whereas cell apoptosis was significantly increased (p < 0.05). Western blot and immunohistochemistry results showed that the levels of HIF-1α, ECM production pathway-related proteins, and TGFβ/Smad signaling pathway-related proteins in the GEM + TQ treatment group were further decreased compared to the control group or the GEM treatment group (p < 0.05). Conclusion: In pancreatic cancer cells, TQ can promote apoptosis, inhibit migration, invasion, and metastasis, and enhance the sensitivity to GEM. The underlying mechanism may involve the regulation of ECM production through the TGFβ/Smad pathway, in which HIF-1α plays a key role.

Hypoxia regulates adipose mesenchymal stem cells proliferation, migration, and nucleus pulposus-like differentiation by regulating endoplasmic reticulum stress via the HIF-1α pathway

ObjectiveHypoxia can promote stem cell proliferation and migration through HIF-1α. Hypoxia can regulate cellular endoplasmic reticulum (ER) stress. Some studies have reported the relationship among hypoxia, HIF-α, and ER stress, however, while little is known about HIF-α and ER stress in ADSCs under hypoxic conditions. The purpose of the study was to investigate the role and relationship of hypoxic conditions, HIF-1α and ER stress in regulating adipose mesenchymal stem cells (ADSCs) proliferation, migration, and NPC-like differentiation.MethodADSCs were pretreated with hypoxia, HIF-1α gene transfection, and HIF-1α gene silence. The ADSCs proliferation, migration, and NPC-like differentiation were assessed. The expression of HIF-1α in ADSCs was regulated; then, the changes of ER stress level in ADSCs were observed to investigate the relationship between ER stress and HIF-1α in ADSCs under hypoxic conditions.ResultThe cell proliferation and migration assay results show that hypoxia and HIF-1α overexpression can significantly increase the ADSCs proliferation and migration, while HIF-1α inhibition can significantly decrease the ADSCs proliferation and migration. The HIF-1α and co-cultured with NPCs played an important role in the directional differentiation of ADSCs into NPCs. The hypoxia-regulated ER stress in ADSCs through the HIF-1α pathway, thereby regulating the cellular state of ADSCs, was also observed.ConclusionHypoxia and HIF-1α play important roles in proliferation, migration, and NPC-like differentiation of ADSCs. This study provides preliminary evidence that HIF-1α-regulated ER stress thus affects ADSCs proliferation, migration, and differentiation. Therefore, HIF-1α and ER may serve as key points to improve the efficacy of ADSCs in treating disc degeneration.

Osteoblast-intrinsic defect in glucose metabolism impairs bone formation in type II diabetic male mice.

Skeletal fragility is associated with type 2 diabetes mellitus (T2D), but the underlying mechanism is not well understood. Here, in a mouse model for youth-onset T2D, we show that both trabecular and cortical bone mass is reduced due to diminished osteoblast activity. Stable isotope tracing in vivo with 13C-glucose demonstrates that both glycolysis and glucose fueling of the TCA cycle are impaired in diabetic bones. Similarly, Seahorse assays show suppression of both glycolysis and oxidative phosphorylation by diabetes in bone marrow mesenchymal cells as a whole, whereas single-cell RNA sequencing reveals distinct modes of metabolic dysregulation among the subpopulations. Metformin not only promotes glycolysis and osteoblast differentiation in vitro, but also improves bone mass in diabetic mice. Finally, osteoblast-specific overexpression of either Hif1a, a general inducer of glycolysis, or Pfkfb3 which stimulates a specific step in glycolysis, averts bone loss in T2D mice. The study identifies osteoblast-intrinsic defects in glucose metabolism as an underlying cause of diabetic osteopenia, which may be targeted therapeutically.