Upregulation Of Hypoxia-inducible Factor-1α Research Articles

Caulerpa chemnitzia polysaccharide exerts immunomodulatory activity in macrophages by mediating the succinate/PHD2/HIF-1α/IL-1β pathway

Algal polysaccharide is an important food functional factor with diverse bioactive and low toxicity. Previous studies have confirmed Caulerpa chemnitzia polysaccharides (CRVP) have immunomodulatory activity, but the immunomodulatory mechanism of CRVP in macrophages has not been thoroughly explored yet. In our research, we found that CRVP has outstanding immunomodulatory activity in macrophages, which is reflected in promoting cell proliferation, upregulating cytokines (IL-1β, IL-6, and TNF-α) expression, and increasing NO and ROS levels. Additionally, the result of joint analysis of untargeted metabolomics showed metabolism played a major role in the immunomodulatory of CRVP and suggested succinic acid was a key metabolite. Further verification indicated that the accumulation of succinic acid in macrophages after administered with CRVP, induced the down-regulation of prolyl hydroxylase domain 2 (PHD2) and up-regulation of hypoxia-inducible factor-1α (HIF-1α), thereby enhancing IL-1β expression. Together, the immunomodulatory activity of CRVP in macrophages via succinate/PHD2/HIF-1α/IL-1β pathway.

Pathophysiological Implications of Protein Lactylation in Pancreatic Epithelial Tumors.

Protein lactylation is a post-translational modification associated with glycolysis. Although recent evidence indicates that protein lactylation is involved in epigenetic gene regulation, its pathophysiological significance remains unclear, particularly in neoplasms. Herein, we investigated the potential involvement of protein lactylation in the molecular mechanisms underlying benign and malignant pancreatic epithelial tumors, as well as its role in the response of pancreatic cancer (PC) cells to gemcitabine. Increased lactylation was observed in the nuclei of intraductal papillary mucinous adenoma, non-invasive intraductal papillary mucinous carcinoma, and invasive carcinoma, in parallel to the upregulation of hypoxia-inducible factor-1α. This observation indicated that a hypoxia-associated increase in nuclear protein lactylation could be a biochemical hallmark in pancreatic epithelial tumors. The standard PC chemotherapy drug gemcitabine suppressed histone lactylation in vitro, suggesting that histone lactylation might be relevant to its mechanism of action. Taken together, our findings suggest that protein lactylation may be involved in the development of pancreatic epithelial tumors and could represent a potential therapeutic target for PC.

Hypoxia-inducible factor upregulation by roxadustat attenuates drug reward by altering brain iron homoeostasis

Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the upregulation of Hypoxia-inducible factor-1α (HIF-1α) expression by roxadustat (Rox), a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α, administered either systemically or locally into selected brain regions, suppressed morphine (Mor)-induced conditioned place preference (CPP). A similar effect was observed with methamphetamine (METH). Moreover, Rox also inhibited the expression of both established and reinstated Mor-CPP and promoted the extinction of Mor-CPP. Additionally, the elevation of HIF-1α enhanced hepcidin/ferroportin 1 (FPN1)-mediated iron efflux and resulted in cellular iron deficiency, which led to the functional accumulation of the dopamine transporter (DAT) in plasma membranes due to iron deficiency-impaired ubiquitin degradation. Notably, iron-deficient mice generated via a low iron diet mimicked the effect of Rox on the prevention of Mor- or METH-CPP formation, without affecting other types of memory. These data reveal a novel mechanism for HIF-1α and iron involvement in substance use disorder, which may represent a potential novel therapeutic strategy for the treatment of drug abuse. The findings also repurpose Rox by suggesting a potential new indication for the treatment of substance use disorder.

MiR-31 ameliorates type 2 diabetic vascular damage through up-regulation of hypoxia-inducible factor-1α/vascular endothelial growth factor-A.

microRNA may be a new therapeutic direction for diabetes. As a typical tumor marker, miR-31 is involved in a variety of metabolic diseases, but the specific role is still unclear. This study aimed to investigate the effect of miR-31 on type 2 diabetes mellitus and its accompanying vascular injury, as well as on the effects of hypoxia-inducible factor-1α inhibitor (HIF1AN), hypoxia-inducible factor (HIF)-1α, and vascular endothelial growth factor (VEGF)-A expression in vitro and in vivo. In vitro, a model of high-fat and high-glucose-induced human aortic endothelial cell (HAEC) injury was established to simulate diabetes mellitus (DM). Cell functions were compared between the control group, the DM damage group, and the group transfected with miR-31 after DM damage. In vivo, overexpressing miR-31 FVB mice and FVB mice were divided into the control and induced type 2 diabetes mellitus groups. Type 2 diabetes mellitus models were induced by a high-fat diet combined with streptozotocin. The lipid metabolism levels, viscera, and vascular damage were compared between the control and type 2 diabetes mellitus groups. In vitro, miR-31 improved the proliferation ability of damaged cells by targeting HIF1AN and up-regulating the expression of HIF-1α and VEGF-A. In vivo, miR-31 ameliorated the development of type 2 diabetes mellitus, disturbance of glucose and lipid metabolism, and damage to some organs. Meanwhile, miR-31 had a protective effect on vascular damage complicated by type 2 diabetes mellitus by increasing the levels of HIF-1α and VEGF-A. Our experiments show that miR-31 can delay the progression of type 2 diabetes mellitus and ameliorate diabetic vascular injury.

Depletion of plasmacytoid dendritic cells and HIF-1α inhibition enhance immunotherapy against hepatocellular carcinoma

Abstract Hepatocellular Carcinoma (HCC) is one of the deadliest forms of cancer. Recent years have seen significant advances for HCC treatment, but up to 70% of patients remain at high risk for recurrence necessitating the urgent need for more effective therapies. Plasmacytoid dendritic cells (pDCs) heavily infiltrate liver tumor tissues, contribute to an immunosuppressive tumor microenvironment (TEM), and promote HCC growth. Furthermore, hypoxia often occurs in HCC tumor tissues and plays the central role of an immunosuppressive TME. A hypoxic TME enhances pDC recruitment into tumor tissues via the upregulation of hypoxia-inducible factor 1α (HIF-1α). Here we show that the distribution of pDCs does not co-localized with hypoxic areas in HCC. In the immunocompetent HCC mouse model, depletion of pDCs using the antibody or HIF-1α inhibitor echinomycin significantly suppressed tumor growth. The combination of pDC depletion and HIF-1α inhibition suppressed HCC growth more effectively. Both treatments reshaped the TME with changes of the cytokine profile and increased tumor-infiltrating CD8 T cells. Reduced basic helix-loop-helix transcription factor E2-2 expression by treatments abrogated protumor functions of pDCs in HCC resulting in reactivating tumor-reactive CD8 T cells. This study demonstrates that targeting both pDCs and HIF-1α may serve as more effective immunotherapy for HCC.

HIF-1α enhances autophagy to alleviate apoptosis in marginal cells in the stria vascular in neonatal rats under hypoxia

In the cochlea, various factors, such as noise, aging, and inflammation, induce hypoxia, resulting in the up-regulation of hypoxia inducible factor-1α (HIF-1α). The role of HIF-1α in hypoxic marginal cells (MCs) of the stria vascularis is unknown. This study examined HIF-1α-mediated autophagy in MCs of neonatal rats and its mechanism of action. We found that an increase in HIF-1α expression was associated with autophagy and apoptosis. Treatment with PX478, a specific inhibitor of HIF-1α, decreased the HIF-1α level, and the degree of autophagy decreased in hypoxic and apoptotic MCs. By contrast, treatment with DMOG, an activator of HIF-1α, increased autophagy and decreased apoptosis. Both PX478 and DMOG had no effect on the apoptotic rate after treatment with 3-methyladenine, an inhibitor of autophagy, indicating that HIF-1α promoted autophagy to protect MCs from hypoxia-induced apoptosis. Lastly, we silenced Bnip3(Bcl-2/adenovirus E1B 19-kDa interacting protein) in MCs to identify the mechanism of action. Our results show that the HIF-1α-BNIP3 pathway mediates the anti-apoptotic effects through an increase in autophagy.

Hypoxia-induced long noncoding RNA NR2F1-AS1 maintains pancreatic cancer proliferation, migration, and invasion by activating the NR2F1/AKT/mTOR axis

Accumulating evidence has demonstrated the essential role of long noncoding RNAs (lncRNAs) in various types of human cancer, including pancreatic cancer (PC). However, the functions and regulatory mechanisms of nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) that are responsible for its role in the malignant progression of PC cells remains to be investigated. In this study, the biological effects of NR2F1-AS1 and NR2F1 in PC were investigated by in vitro and in vivo experiments. The mechanisms of NR2F1-AS1 were monitored by bioinformatic predictive analysis and confirmatory experiments. Our results indicated that NR2F1-AS1 was overexpressed and positively correlated with poor survival in PC. Depletion of NR2F1-AS1 restrained PC cell proliferation, migration, invasion, and suppressed xenograft tumor growth and metastasis in vitro and in vivo. Mechanistic experiments suggested that NR2F1-AS1 positively regulated the neighboring NR2F1 gene, which subsequently activated AKT/mTOR signaling, resulting in the upregulation of hypoxia-inducible factor-1α (HIF-1α). Further investigations elucidated that NR2F1-AS1 expression was transcriptionally regulated by HIF-1α under hypoxia. These findings demonstrated that hypoxia-induced NR2F1-AS1 expression directly increased NR2F1 levels to promote PC cell proliferation, migration, and invasion by activating AKT/mTOR signaling. Together, these findings suggest that NR2F1-AS1 could be a prospective therapeutic target for PC.

Targeted downregulation of HIF-1α for restraining circulating tumor microemboli mediated metastasis

Tumor metastasis is directly correlated to poor prognosis and high mortality. Circulating tumor cells (CTCs) play a pivotal role in metastatic cascades, of which CTC clusters is highly metastatic compared to single CTCs. Although platelets and neutrophils within the bloodstream could further exacerbate the pro-metastatic effect of single CTCs, the influence of platelets and neutrophils on CTC clusters mediated metastasis remains unclear. In this study, a pro-metastatic complex composed of CTC clusters, platelets and neutrophils, namely circulating tumor microemboli (CTM), was identified in vivo among different metastatic tumor, which was demonstrated with highly upregulation of hypoxia-inducible factor-1α (HIF-1α). While knock-out of HIF-1α or therapeutically downregulating of HIF-1α via HIF-1α inhibitor (BAY87–2243)-loaded neutrophil cyto-pharmaceuticals (PNEs) could efficiently restrain CTM mediated lung metastasis. The underlying mechanism of metastasis inhibition was attributed to the downregulation of HIF-1α-associated PD-L1, which would enhance immune response for inhibiting metastatic cells. Thus, our work here illustrates that hypoxia was an essential factor in promoting CTM colonization in lung. More importantly, we provide a promising strategy by targeted downregulation of HIF-1α in CTM via neutrophil cyto-pharmaceuticals for treatment of CTM mediated metastasis.

Self-Remedied Nanomedicine for Surmounting the Achilles' Heel of Photodynamic Tumor Therapy.

Oxygen-dependent photodynamic therapy (PDT) could exacerbate tumor hypoxia to induce the upregulation of hypoxia-inducible factor-1α (HIF-1α), which would promote tumor growth and metastasis. In this paper, a self-remedied nanomedicine is developed based on a photosensitizer and a HIF-1α inhibitor to surmount the Achilles' heel of PDT for enhanced antitumor efficacy. Specifically, the nanomedicine (designated as CYC-1) is prepared by the self-assembly of chlorine e6 (Ce6) and 3-(5'-hydroxy-methyl-2'-furyl)-1-benzylindazole (YC-1) through π-π stacking and hydrophobic interactions. Of special note, carrier-free CYC-1 holds an extremely high drug loading rate and avoids excipient-triggered adverse reactions. Intravenously administered CYC-1 prefers to accumulate in the tumor tissue for effective cellular uptake. More importantly, it is verified that CYC-1 is capable of inhibiting the HIF-1α activity, thereby improving its PDT efficacy on tumor suppression. Besides, CYC-1 has the overwhelming superiority in restraining tumor proliferation over the combined administration of Ce6 and YC-1, which highlights the advantage of this self-remedied strategy in drug delivery and tumor therapy. This study sheds light on the development of self-delivery nanomedicine for efficient PDT against malignancies.

Oxidative Stress-Induced Sirtuin1 Downregulation Correlates to HIF-1α, GLUT-1, and VEGF-A Upregulation in Th1 Autoimmune Hashimoto's Thyroiditis.

In Hashimoto’s thyroiditis (HT), oxidative stress (OS) is driven by Th1 cytokines’ response interfering with the normal function of thyrocytes. OS results from an imbalance between an excessive production of reactive oxygen species (ROS) and a lowering of antioxidant production. Moreover, OS has been shown to inhibit Sirtuin 1 (SIRT1), which is able to prevent hypoxia-inducible factor (HIF)-1α stabilization. The aims of this study were to determine the involvement of NADPH-oxidases (NOX), SIRT1, and HIF-1α in HT pathophysiology as well as the status of antioxidant proteins such as peroxiredoxin 1 (PRDX1), catalase, and superoxide dismutase 1 (SOD1). The protein expressions of NOX2, NOX4, antioxidant enzymes, SIRT1, and HIF-1α, as well as glucose transporter-1 (GLUT-1) and vascular endothelial growth factor A (VEGF-A), were analyzed by Western blot in primary cultures of human thyrocytes that were or were not incubated with Th1 cytokines. The same proteins were also analyzed by immunohistochemistry in thyroid samples from control and HT patients. In human thyrocytes incubated with Th1 cytokines, NOX4 expression was increased whereas antioxidants, such as PRDX1, catalase, and SOD1, were reduced. Th1 cytokines also induced a significant decrease of SIRT1 protein expression associated with an upregulation of HIF-1α, GLUT-1, and VEGF-A proteins. With the exception of PRDX1 and SOD1, similar results were obtained in HT thyroids. OS due to an increase of ROS produced by NOX4 and a loss of antioxidant defenses (PRDX1, catalase, SOD1) correlates to a reduction of SIRT1 and an upregulation of HIF 1α, GLUT-1, and VEGF-A. Our study placed SIRT1 as a key regulator of OS and we, therefore, believe it could be considered as a potential therapeutic target in HT.

Non-viral gene delivery of HIF-1α promotes angiogenesis in human adipose-derived stem cells

Stable and mature vascular formation is a current challenge in engineering functional tissues. Transient, non-viral gene delivery presents a unique platform for delivering genetic information to cells for tissue engineering purposes and to restore blood flow to ischemic tissue. The formation of new blood vessels can be induced by upregulation of hypoxia-inducible factor-1α (HIF-1), among other factors. We hypothesized that biodegradable polymers could be used to efficiently deliver the HIF-1α gene to human adipose-derived stromal/stem cells (hASCs) and that this treatment could recruit an existing endogenous endothelial cell population to induce angiogenesis in a 3D cell construct in vitro. In this study, end-modified poly(β-amino ester) (PBAE) nanocomplexes were first optimized for transfection of hASCs and a new biodegradable polymer with increased hydrophobicity and secondary amine structures, N'-(3-aminopropyl)-N,N-dimethylpropane-1,3-diamine end-modified poly(1,4-butanediol diacrylate-co-4-amino-1-butanol), was found to be most effective. Optimal PBAE nanocomplexes had a hydrodynamic diameter of approximately 140 nm and had a zeta potential of 30 mV. The PBAE polymer self-assembled with HIF-1α plasmid DNA and treatment of hASCs with these nanocomplexes induced 3D vascularization. Cells transfected with this polymer-DNA complex were found to have 106-fold upregulation HIF-1α expression, an approximately 2-fold increase in secreted VEGF, and caused the formation of vessel tubules compared to an untransfected control. These gene therapy biomaterials may be useful for regenerative medicine. Statement of SignificanceNot only is the formation of stable vasculature a challenge for engineering human tissues in vitro, but it is also of valuable interest to clinical applications such as peripheral artery disease. Previous studies using HIF-1α to induce vascular formation have been limited by the necessity of hypoxic chambers. It would be advantageous to simulate endogenous responses to hypoxia without the need for physical hypoxia. In this study, 3D vascular formation was shown to be inducible through non-viral gene delivery of HIF-1α with new polymeric nanocomplexes. A biodegradable polymer N'-(3-aminopropyl)-N,N-dimethylpropane-1,3-diamine end-modified poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) demonstrates improved transfection of human adipose-derived stem cells. This nanobiotechnology could be a promising strategy for the creation of vasculature for tissue engineering and clinical applications.

LOXL2 upregulates hypoxia‑inducible factor‑1α signaling through Snail‑FBP1 axis in hepatocellular carcinoma cells.

Lysyl oxidase-like 2 (LOXL2), a member of the lysyl oxidase gene family, is involved in the progression of hepatocellular carcinoma progression and metastasis. Increased expression of LOXL2 has been identified in several types of cancer, including hepatocellular carcinoma. Recently, LOXL2 has been reported to promote epithelial-mesenchymal transition by reducing E-cadherin expression via the upregulation of Snail expression. The present study provided evidence demonstrating that LOXL2 inhibited the expression of fructose-1, 6-biphosphatase (FBP1) and enhanced the glycolysis of Huh7 and Hep3B hepatocellular carcinoma cell lines in a Snail-dependent manner. Overexpression of the point-mutated form of LOXL2 [LOXL2(Y689F)], which lacks enzymatic activity, does not affect the expression of Snail1 or FBP1. Notably, targeting extracellular LOXL2 of Huh7 cells with a therapeutic antibody was unable to abolish its regulation on the expression of Snail and FBP1. Knockdown of LOXL2 also interrupted the angiogenesis of Huh7 and Hep3B cells, and this effect could be rescued by the overexpression of Snail. Furthermore, upregulation of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) expression was observed in Huh7 and Hep3B cells expressing wild-type LOXL2. Notably, the selective LOXL2 inhibitor LOXL2-IN-1 could upregulate the expression of FBP1 and inhibit the expression of Snail, HIF-1α and VEGF in HCC cells, but not in FBP1-knockdown cells. The results of the present study indicated that the intracellular activity of LOXL2 upregulated HIF-1α/VEGF signaling pathways via the Snail-FBP1 axis, and this phenomenon could be inhibited by LOXL2 inhibition. Collectively, these findings further support that LOXL2 exhibits an important role in the progression of hepatocellular carcinoma and implicates LOXL2 as a potential therapeutic agent for the treatment of this disease.

Reciprocal upregulation of hypoxia-inducible factor-1α and persistently enhanced placental adenosine signaling contribute to the pathogenesis of preeclampsia.

Recent evidence indicates that elevated placental adenosine signaling contributes to preeclampsia (PE). However, the molecular basis for the chronically enhanced placental adenosine signaling in PE remains unclear. Here, we report that hypoxia-inducible factor-1α (HIF-1α) is crucial for the enhancement of placental adenosine signaling. Utilizing a pharmacologic approach to reduce placental adenosine levels, we found that enhanced adenosine underlies increased placental HIF-1α in an angiotensin receptor type 1 receptor agonistic autoantibody (AT1 -AA)-induced mouse model of PE. Knockdown of placental HIF-1α in vivo suppressed the accumulation of adenosine and increased ecto-5'-nucleotidase (CD73) and adenosine A2B receptor (ADORA2B) in the placentas of PE mouse models induced by AT1 -AA or LIGHT, a TNF superfamily cytokine (TNFSF14). Human in vitro studies using placental villous explants demonstrated that increased HIF-1α resulting from ADORA2B activation facilitates the induction of CD73, ADORA2B, and FLT-1 expression. Overall, we demonstrated that (a) elevated placental HIF-1α by AT1 -AA or LIGHT upregulates CD73 and ADORA2B expression and (b) enhanced adenosine signaling through upregulated ADORA2B induces placental HIF-1α expression, which creates a positive feedback loop that promotes FLT-1 expression leading to disease development. Our results suggest that adenosine-based therapy targeting the malicious cycle of placental adenosine signaling may elicit therapeutic effects on PE.

Downregulation of Proline Hydroxylase 2 and Upregulation of Hypoxia-Inducible Factor 1α are Associated with Endometrial Cancer Aggressiveness.

IntroductionProline hydroxylase 2 (PHD2) is involved in tumorigenesis. This study aimed to examine PHD2 and hypoxia-inducible factor 1α (HIF-1α) expression in different endometrial tissues and explore the correlations between PHD2 and HIF-1α expression with clinicopathological characteristics of endometrial cancer.MethodsWe collected 50 tissue sections of endometrial adenocarcinoma, 30 of atypical endometrial hyperplasia, and 30 of control normal endometrium. The expression of PHD2 was detected by PCR, Western blot, and immunohistochemical analysis.ResultsPHD2 mRNA and protein levels reduced in endometrial cancer tissues compared to normal endometrium (p<0.05). In contrast, HIF-1α expression levels increased in endometrial cancer tissues compared to normal endometrium (p<0.05). In addition, PHD2 and HIF-1α levels were correlated with lymphovascular stromal invasion (LVSI), postoperative FIGO stage, and lymph node metastasis of endometrial cancer (p<0.05).ConclusionOur findings suggest that reduced expression of PHD2 and increased expression of HIF-1α are associated with endometrial cancer aggressiveness. PHD2 might be a novel biomarker and a potential target for endometrial cancer management.

Supramolecular Polymer Hydrogels for Drug-Induced Tissue Regeneration.

Supramolecular polymers self-assemble into nanofibers, micelles, and other nanostructures through weak noncovalent interactions between subunits. Such systems possess attractive properties for use in a variety of practical settings such as energy, sustainability, and healthcare. In regenerative medicine, a common approach involves implanting a supramolecular material containing cell and growth factor binding motifs directly into a diseased or traumatized tissue defect, whereupon it interacts with and/or recruits components of the biological system to induce tissue healing. Here we introduce a supramolecular therapeutic in which tissue regeneration is orchestrated by a supramolecular polymer prodrug implanted subcutaneously in a remote tissue. Our approach exploits a hydrophobic small-molecule inhibitor of prolyl hydroxylase enzyme as both a regeneration-inducing therapeutic and a structure-directing agent in a supramolecular polymer that forms shear-thinning nanofiber hydrogels. Subcutaneous injection of the supramolecular hydrogel in the back of mice wounded with a critical-sized defect in the ear led to transient upregulation of hypoxia inducible factor-1α and regeneration of ear tissue in a manner reminiscent of epimorphic regeneration. This drug-induced regeneration strategy utilizes a simple and translatable supramolecular design, eliminates the need for delivery of biologics ( e. g., growth factors, cells), and avoids implantation of a foreign material directly in a tissue defect.

Up-regulation of hypoxia inducible Factor-1α in patients with diabetic nephropathy.

To study the role of hypoxia inducible factor-1α (HIF-1α) in patients with diabetic nephropathy (DN). In total, 133 participants were selected to conduct the investigation, parameters such as fasting blood sugar (FBS), blood urea nitrogen (BUN), and urine albumin-creatinine ratio (UACR) were tested and recorded. The biopsy assessment was conducted when renal function or urinary abnormalities. Western blotting was used to test the expression of serum HIF-1α in all patients and control group. The values of FBS, BUN, and UACR were higher in DN and diabetes groups than in the healthy control. The values of FBG, BUN, and UACR were higher in DN patients than in the diabetes patients with no nephropathy. eGFR in DN patients was lower than the other two groups. The expression of HIF-1α was higher than both diabetes patients with no nephropathy and healthy control, P < 0.05. Patients with lots of albuminuria showed the highest expression of HIF-1α than the other groups. HIF-1α in normoalbuminuria and microalbuminuria groups showed no significant difference. HIF-1α was up-regulated in DN patients, which might give clinical basis to the role of HIF-1α in the development of DN.

Hypoxia-Inducible Factor 1-α (HIF-1α) Induces Apoptosis of Human Uterosacral Ligament Fibroblasts Through the Death Receptor and Mitochondrial Pathways.

BackgroundHypoxia induces cell apoptosis in the uterosacral ligaments of patients with pelvic organ prolapse by upregulation of hypoxia-inducible factor-1α (HIF-1α). This study aimed to investigate the effects of HIF-1α on human uterosacral ligament fibroblasts (hUSLFs) following treatment with the chemical inducer of hypoxia, cobalt chloride (CoCl2), and to explore the underlying mechanisms.Material/MethodsTen women who underwent hysterectomy for benign disease provided uterosacral ligament tissue for cell extraction. Following CoCl2 treatment, cell viability of isolated and cultured hUSLFs was evaluated by the MTT assay. JC-1 fluorescence mitochondrial imaging was used to study the change in mitochondrial membrane potential. Cell apoptosis and expression of apoptosis-associated proteins and collagen type I alpha 1 (COL1A1) were measured by flow cytometry, TUNEL and Western blot, respectively.ResultsHypoxia increased the expression of HIF-1α and increased cell apoptosis, decreased cell viability and expression levels of COL1A1. The JC-1 assay showed that the mitochondrial membrane potential was reduced and caspase-8, and -9 inhibitors partly reduced hUSLF apoptosis. HIF-1α treatment downregulated the expression of cellular FLICE inhibitory protein (c-FLIP), decoy receptor 2 (DcR2), and the ratio of Bcl-2 to Bax, and upregulated the expression tumor necrosis factor related apoptosis-inducing ligand (TRAIL), death receptor 5 (DR5) or TRAIL-R2, Fas, Bcl-2 interacting protein 3 (BNIP3), and cytochrome C, and increased the activation of caspase-3, caspase-8, and caspase-9, all of which were reversed by knockdown of HIF-1α.ConclusionsHIF-1α significantly induced apoptosis of hUSLFs through both the cell death receptor and the mitochondrial-associated apoptosis pathways.

PTEN inhibition enhances angiogenesis in an in vitro model of ischemic injury by promoting Akt phosphorylation and subsequent hypoxia inducible factor-1α upregulation

Angiogenesis is an important pathophysiological response to cerebral ischemia. PTEN is a lipid phosphatase whose loss activates PI3K/Akt signaling, which is related to HIF-1α upregulation and enhanced angiogenesis in human cancer cells. However, the specific roles of PTEN in endothelial cell functions and angiogenesis after cerebral ischemia remain unknown. Therefore, we sought to examine the potential effects of PTEN inhibition on post-ischemic angiogenesis in human blood vessel cells and to determine the underlying mechanism. In this present study, human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation (OGD), cell proliferation, migration and apoptosis, in vitro tube formation and expression of PTEN/Akt pathway and angiogenic factors were examined in HUVECs after treatment with PTEN inhibitor bisperoxovanadium (bpV) at different doses. The results showed that bpV significantly increased the cell proliferation and reduced cell apoptosis indicating that the drug exerts a cytoprotective effect on HUVECs with OGD exposure. bpV also enhanced cell migration and tube formation in HUVECs following OGD, and upregulated HIF-1α and VEGF expressions, but attenuated endostatin expression. Additionally, western blotting analysis demonstrated that Akt phosphorylation in HUVECs was significantly increased after bpV treatment. These findings suggest that PTEN inhibition promotes post-ischemic angiogenesis in HUVECs after exposure to OGD and this enhancing effect might be achieved through activation of the Akt signal cascade.

Neuroprotective effect of electroacupuncture and upregulation of hypoxia-inducible factor-1α during acute ischaemic stroke in rats.

Acupuncture is a traditional method that has been widely used in various fields of medicine with therapeutic effect. However, evidence of effectiveness to support the application of electroacupuncture (EA) during the process of ischaemia is scarce. To investigate dynamic changes in hypoxia-inducible factor (HIF)-1α expression as well as its association with neurological status in rats subjected to acute ischaemic stroke and EA intervention. Forty adult male rats were randomly divided into three groups that received sham surgery (Control group, n=10) or underwent middle cerebral artery occlusion and EA (MCAO+EA group, n=15) or minimal acupuncture as a control treatment (MCAO+MA group, n=15). The rats in the MCAO+EA and MCAO+MA groups received EA or acupuncture without any electrical current, respectively, during 90 min of ischaemia. Rats in the Control group received the same surgical procedure but without MCAO. EA involved electrical stimulation of needles inserted into the quadriceps at 50 Hz frequency and 3 mA current intensity. Neurological status was evaluated on postoperative day 1, and cerebral infarction volume (IV) and HIF-1α expression 24 hours later. Neurological scores were improved and cerebral IV was decreased in the MCAO+EA group compared to the MCAO+MA group (both p<0.05). Moreover, HIF-1α expression was higher in the MCAO+EA group versus the MCAO+MA group (p<0.05). EA enhanced recovery of neurological function, decreased cerebral IV and increased HIF-1α expression in ischaemic rats. Further research is needed to determine whether EA is effective for stroke treatment through the stimulation of muscle contraction.

Tibial dyschondroplasia is highly associated with suppression of tibial angiogenesis through regulating the HIF-1\u03b1/VEGF/VEGFR signaling pathway in chickens

Tibial dyschondroplasia (TD) is an intractable poultry problem that is characterized by the appearance of non-vascularized and non-mineralized cartilage masses in tibial growth plates (TGPs). However, the role of angiogenesis inhibition in the occurrence of TD remains unknown. In this study, we found that, compared to low-altitude Arbor Acres chickens (AACs), high-altitude Tibetan chickens showed higher tibial vascular distributions that were accompanied by up-regulation of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGFA) and VEGF receptors. These observations provide insights into hypoxia-induced angiogenesis, which may be related to the absence of TD in high-altitude native Tibetan chickens. Importantly, hypoxia experiments also showed that during hypoxia, tibial angiogenesis was enhanced, which was due to pro-angiogenic factor up-regulation (including VEGFA, VEGFR1, VEGFR2, and IL-8), in AACs. Moreover, we observed that thiram-induced TD could strongly inhibit tibial angiogenesis in the hypertrophic zone through coordinated down-regulation of HIF-1α and pro-angiogenic factors, leading to a disruption in the blood supply to the TGP. Taken together, these findings reveal that the occurrence of TD is highly associated with inhibition of tibial angiogenesis through down-regulated expression of HIF-1α, VEGFA and VEGF receptors, which results in suppression of TGP development.