bims-hypoxi 2021-05-16 papers

bims-hypoxi

Biomed News

on Hypoxia and HIF1-alpha

Issue of 2021‒05‒16
twenty-five papers selected by
Ashish Kaul
University of Tsukuba

Intermittent hypoxia preconditioning protects WRL68 cells against oxidative injury: Involvement of the PINK1/Parkin-mediated mitophagy regulated by nuclear respiratory factor 1.
The interplay between HIF-1α and long noncoding GAS5 regulates the JAK1/STAT3 signalling pathway in hypoxia-induced injury in myocardial cells.
Cephalomannine inhibits hypoxia-induced cellular function via the suppression of APEX1/HIF-1α interaction in lung cancer.
Dextran Sulfate Effects EMT of Human Gastric Cancer Cells by Reducing HIF-1α/ TGF-β.
Inhibition of miR-1224 suppresses hypoxia/reoxygenation-induced oxidative stress and apoptosis in cardiomyocytes through targeting GPX4.
LY‑294002 enhances the chemosensitivity of liver cancer to oxaliplatin by blocking the PI3K/AKT/HIF‑1α pathway.
Hypoxia-inducible factor-1α regulates PI3K/AKT signaling through microRNA-32-5p/PTEN and affects nucleus pulposus cell proliferation and apoptosis.
TFB2M activates aerobic glycolysis in hepatocellular carcinoma cells through the NAD+ /SIRT3/HIF-1α signaling.
Hypoxia-induced HIF1α dependent COX2 promotes ovarian cancer progress.
Effect of hypoxia factors gene silencing on ROS production and metabolic status of A375 malignant melanoma cells.
STING regulates metabolic reprogramming in macrophages via HIF-1α during Brucella infection.
Improved delivery system for celastrol-loaded magnetic Fe3O4/α-Fe2O3 heterogeneous nanorods: HIF-1α-related apoptotic effects on SMMC-7721 cell.
HIF-1α may promote glycolysis in psoriasis vulgaris via upregulation of CD147 and GLUT1.
Downregulation of both mismatch repair and non-homologous end-joining pathways in hypoxic brain tumour cell lines.
Endoplasmic reticulum stress regulates the intestinal stem cell state through CtBP2.
Cynaroside prevents macrophage polarization into pro-inflammatory phenotype and alleviates cecal ligation and puncture-induced liver injury by targeting PKM2/HIF-1α axis.
Hypoxia-dependent drivers of melanoma progression.
[Identification of hypoxia-specific therapeutic targets in multiple myeloma].
The Role of Autophagy in Hypoxia-Induced Neuroinflammation.
Oral Epithelial Cells Distinguish between Candida Species with High or Low Pathogenic Potential through MicroRNA Regulation.
Hypoxia-inducible factor prolyl hydroxylase inhibitor roxadustat (FG-4592) protects against renal ischemia/reperfusion injury by inhibiting inflammation.
Hypoxia-induced retinal pigment epithelium cell-derived bFGF promotes the migration and angiogenesis of HUVECs through regulating TGF-β1/smad2/3 pathway.
The YAP/HIF-1α/miR-182/EGR2 axis is implicated in asthma severity through the control of Th17 cell differentiation.
ATF5 and HIF1α cooperatively activate HIF1 signaling pathway in esophageal cancer.
HIF1α-mediated RelB/APOBEC3B downregulation allows Hepatitis B Virus persistence.

Mitochondrion. 2021 Apr 30. pii: S1567-7249(21)00058-1. [Epub ahead of print]59 113-122

Intermittent hypoxia preconditioning protects WRL68 cells against oxidative injury: Involvement of the PINK1/Parkin-mediated mitophagy regulated by nuclear respiratory factor 1.

Yapeng Lu, Jiangpei Bian, Huiwen Kan, Wangwang Ding, Dan Wang, Xueting Wang, Qianqian Luo, Xiaomei Wu, Li Zhu.

  The protective effect of intermittent hypoxia (IH) preconditioning against oxidative injury in hepatic cells was investigated and the involvement of the PINK1/Parkin-mediated mitophagy regulated by nuclear respiratory factor 1 (NRF-1) was evaluated. The results showed that IH preconditioning protected HepG2 cells against oxygen and glucose deprivation/reperfusion (OGD/Rep)-induced injury and protected WRL68 cells against H2O2 or AMA-induced oxidative injury. IH preconditioning up-regulated the protein level of NRF-1, PINK1, Parkin, and LC3 II, promoted the recruitment of the cytosolic Parkin, indicating the initiation of the PINK1/Parkin-mediated mitophagy in WRL68 cells. When NRF-1 was down-regulated by NRF-1 specific shRNA, the protein level of PINK1 and Parkin as well as the mitophagy level were significantly decreased. After IH preconditioning, the protein level of PINK1 and the recruitment of Parkin in CCCP-treated group were significantly higher than that of the control group, indicating the increased mitophagy capacity. And the increased mitophagy capacity induced by IH preconditioning was also reduced by down-regulation of NRF-1. Furthermore, the protective effect of IH preconditioning against H2O2-induced oxidative injury in WRL68 cells was inhibited when NRF-1 or PINK1 was down-regulated by specific shRNA. Mitochondrial ROS generation may be responsible for the increased expression of NRF-1 induced by IH preconditioning. In conclusion, the PINK1/Parkin-mediated mitophagy regulated by NRF-1 was involved in IH preconditioning-induced protective effect against oxidative cellular injury in hepatic cells.

Keywords:  Intermittent hypoxia; Mitophagy; Nuclear respiratory factor 1; PINK1; Parkin

DOI:  https://doi.org/10.1016/j.mito.2021.04.012
Cardiovasc Diagn Ther. 2021 Apr;11(2): 422-434

The interplay between HIF-1α and long noncoding GAS5 regulates the JAK1/STAT3 signalling pathway in hypoxia-induced injury in myocardial cells.

Yanwei Li, Bing Song, Jinlei Liu, Yuqiang Li, Jiebing Wang, Na Liu, Wei Cui.

  Background: Long non-coding RNA (lncRNA) GAS5 is associated with hypoxia-induced diseases whereas hypoxia-inducible factor-1α (HIF-1α) plays an important role in hypoxic injury of cells. The current study explores the regulatory functions of GAS5/HIF-1α which co-play in anoxic injury among rat cardiomyocytes H9C2 cells.Methods: Hypoxia in vitro model was established through anoxic incubation while normal culture of H9C2 cells was considered as control. The expression levels of GAS5 and HIF-1α were quantified through RT-qPCR. CCK-8 was applied to determine cell viability. Cell apoptosis rate was calculated using flow cytometry whereas inflammatory cytokines were detected using ELISA method. The impact of downregulating GAS5 or HIF-1α or both upon hypoxic cells was assessed on the basis of changes in cell viability, apoptosis, and inflammatory response. The activity of JAK1/STAT3 signaling was evaluated through RT-qPCR for mRNA expression. AG490 was introduced to inactivate JAK1/STAT3 pathway and to unveil the impact of JAK1/STAT3 signaling on GAS5/HIF-1α and cell viability, apoptosis and inflammation in hypoxic cells.
Results: The results infer that hypoxia suppressed cell viability, promoted inflammation and apoptosis among H9C2 cells. GAS5 or HIF-1α recorded higher expression in hypoxia-induced cells whereas the cell viability got restored with reduction in inflammation and apoptosis. The downregulation of HIF-1α enhanced the protective effect of knocking down GAS5 in hypoxia H9C2 cells. JAK1/STAT3 signaling pathway got activated in hypoxic cells and was regulated by GAS5 and HIF-1α. The inhibition of signaling pathway increased the cell viability but it decreased both inflammation and apoptosis.
Conclusions: GAS5 and HIF-1α could regulate hypoxic injury in H9C2 cells through JAK1/STAT3 signaling pathway. This scenario suggests that the inhibitors of GAS5 and HIF-1α may synergize with AG-490 to protect myocardial cells from hypoxic injury.

Keywords:  JAK1/STAT3; Long non-coding RNA GAS5 (lncRNA GAS5); hypoxia; hypoxia-inducible factor-1α (HIF-1α)

DOI:  https://doi.org/10.21037/cdt-20-773
Cell Death Dis. 2021 May 14. 12(5): 490

Cephalomannine inhibits hypoxia-induced cellular function via the suppression of APEX1/HIF-1α interaction in lung cancer.

Asmat Ullah, Sze Wei Leong, Jingjing Wang, Qing Wu, Mohsin Ahmad Ghauri, Ammar Sarwar, Qi Su, Yanmin Zhang.

Lung cancer (LC) is one of the leading causes of cancer-related death. As one of the key features of tumor microenvironment, hypoxia conditions are associated with poor prognosis in LC patients. Upregulation of hypoxic-induced factor-1α (HIF-1α) leads to the activation of various factors that contribute to the increased drug resistance, proliferation, and migration of tumor cells. Apurinic/apyrimidinic endonuclease-1 (APEX1) is a multi-functional protein that regulates several transcription factors, including HIF-1α, that contribute to tumor growth, oxidative stress responses, and DNA damage. In this study, we explored the mechanisms underlying cell responses to hypoxia and modulation of APEX1, which regulate HIF-1α and downstream pathways. We found that hypoxia-induced APEX1/HIF-1α pathways regulate several key cellular functions, including reactive oxygen species (ROS) production, carbonic anhydrase 9 (CA9)-mediated intracellular pH, migration, and angiogenesis. Cephalomannine (CPM), a natural compound, exerted inhibitory effects in hypoxic LC cells via the inhibition of APEX1/HIF-1α interaction in vitro and in vivo. CPM can significantly inhibit cell viability, ROS production, intracellular pH, and migration in hypoxic LC cells as well as angiogenesis of HUVECs under hypoxia through the inhibition of APEX1/HIF-1α interaction. Taken together, CPM could be considered as a promising compound for LC treatment.

DOI: https://doi.org/10.1038/s41419-021-03771-z
J Cancer. 2021 ;12(11): 3367-3377

Dextran Sulfate Effects EMT of Human Gastric Cancer Cells by Reducing HIF-1α/ TGF-β.

Yun-Ning Huang, Yuan-Yi Xu, Qian Ma, Meng-Qi Li, Jia-Xin Guo, Xiaofei Wang, Xiu Jin, Jing Shang, Long-Xing Jiao.

  The peritoneal implant metastasis is one of the main pathway and main cause for high mortality for gastric cancer metastasis. Researchs show that epithelial-mesenchymal transition (EMT) playing essential role in modulating gastric cancer metastasis, and the expression of hypoxia inducible factor-1α (HIF-1α) can promote EMT in tumor cells. This research aims to explore the influence and mechanism of Dextran Sulfate (DS) affecting EMT of human gastric cancer. In the present study, we found that DS can enter into the cytoplasm and function in it. Inhibition of HIF-1α or DS significantly inhibit the migration and invasion of human gastric cancer cells, and decrease the mRNA and protein expressions of HIF-1α, matrix metalloproteinase-2 (MMP-2), transforming growth factor-β (TGF-β), Twist and N-cadherin (N-cad), rise E-cadherin (E-cad) expression, DS with HIF-1α knockdown has a stronger effect. In vivo studies indicated that compared with using DS or HIF-1α knockdown alone, DS with HIF-1α knockdown can better suppress the volume and number of metastatic tumors, and reduce the mRNA and protein expressions of HIF-1α, MMP-2, TGF-β, Twist and N-cad in metastatic tumor tissues of nude mice. We further demonstrated that the expression of HIF-1α, MMP-2, TGF-β , Twist and N-cad were higher in well and poorly differentiated gastric cancer than paracancerous tissue, and poorly differentiated gastric cancer were even higher, while E-cad expression was opposite. Taken together, this study shows that DS can interfere the expression of HIF-1α, thereby inhibiting TGF-β-mediated EMT of gastric cancer cells, and demonstrated a promising application of DS in gastric cancer therapy.

Keywords:  Dextran sulfate; EMT.; HIF-1α; Human gastric cancer

DOI:  https://doi.org/10.7150/jca.55550
Exp Mol Pathol. 2021 May 11. pii: S0014-4800(21)00044-7. [Epub ahead of print] 104645

Inhibition of miR-1224 suppresses hypoxia/reoxygenation-induced oxidative stress and apoptosis in cardiomyocytes through targeting GPX4.

Guibin Li, Jiali Jin, Shengxin Liu, Kejun Ding, Caizhen Qian.

  We have focused on the underlying role of miR-1224 in cardiomyocyte injury stimulated by hypoxia/reoxygenation (H/R). In the current study, the rat cardiomyocyte cell line H9C2 was used to construct a H/R cell model to validate the cardioprotective effects of miR-1224. Data from the dual-luciferase assay revealed that the glutathione peroxidase 4 (GPX4) was a direct target of miR-1224. Expression of miR-1224, determined using qRT-PCR, was remarkably increased while that of GPX4 protein, evaluated via western blotting, was significantly decreased in cardiomyocytes in response to H/R exposure. ROS generation, superoxide dismutase (SOD) activity, concentrations of malondialdehyde (MDA) and 4-hydroxy aldehydes (4-HNE), and H9C2 cell apoptosis were further evaluated following overexpression of miR-1224 or silencing of GPX4 in H9C2 cells. H9C2 cells under H/R conditions displayed increased synthesis of ROS, along with overexpression of miR-1224 and downregulation of GPX4. SOD activity was significantly decreased while concentrations of MDA and 4-HNE were markedly increased under H/R injury conditions. In addition, miR-1224 mimic or GPX4 siRNA plasmids dramatically enhanced H/R-mediated apoptosis, Bax expression and caspase-3 activity, with a concomitant reduction in Bcl-2 expression. Conversely, inhibition of miR-1224 exerted suppressive effects on oxidative stress and apoptosis in H9C2 cells under H/R conditions. Interestingly, silencing of GPX4 attenuated the negative effects of miR-1224 inhibition. Our results suggested that inhibition of miR-1224 caused resistance to H/R and diminished oxidative stress in vitro through targeting of GPX4.

Keywords:  Cardiomyocytes; Glutathione peroxidase 4; Hypoxia/reoxygenation; Oxidative stress; miRNA-1224

DOI:  https://doi.org/10.1016/j.yexmp.2021.104645
Mol Med Rep. 2021 Jul;pii: 508. [Epub ahead of print]24(1):

LY‑294002 enhances the chemosensitivity of liver cancer to oxaliplatin by blocking the PI3K/AKT/HIF‑1α pathway.

Ruyue Xu, Yinci Zhang, Amin Li, Yongfang Ma, Wenpeng Cai, Li Song, Yinghai Xie, Shuping Zhou, Weiya Cao, Xiaolong Tang.

  Liver cancer remains one of the leading causes of cancer deaths worldwide. The therapeutic effect of oxaliplatin on liver cancer is often limited by acquired resistance of the cancer cells. Abnormal activation of the PI3K/AKT pathway plays an important role in the acquired resistance of oxaliplatin. The present study investigated the effects of the PI3K inhibitor LY‑294002 and AKT inhibitor MK2206 on the chemosensitivity of oxaliplatin‑resistant liver cancer cells and the molecular mechanism involved. An oxaliplatin‑resistant liver cancer cell line HepG2R was developed. MTT assay, clone formation experiments, flow cytometry and Annexin V‑FITC/PI staining were used to determine the proliferation, cycle and apoptosis of HepG2R cells when oxaliplatin was combined with LY‑294002 or MK2206 treatment. The effects of LY‑294002 and MK‑2206 on the abnormal activation of PI3K/AKT pathway and hypoxia inducible factor (HIF)‑1α protein level in HepG2R cells were detected using western blotting. The results indicated that the PI3K/AKT pathway is stably activated in HepG2R cells. Compared with the AKT inhibitor MK2206, the PI3K inhibitor LY‑294002 more effectively downregulated the phosphorylation levels of p85, p110α, p110β, p110γ and AKT in the PI3K/AKT pathway in HepG2R cells, and more effectively inhibited the proliferation of the cells. LY‑294002 enhanced the chemotherapy sensitivity of HepG2R cells to oxaliplatin by inducing G0/G1 phase arrest and increasing the proportion of apoptotic cells. In addition, LY‑294002 reduced the level of HIF‑1α, which is highly expressed in HepG2R cells. It was concluded that LY‑294002 enhanced the chemosensitivity of liver cancer cells to oxaliplatin by inhibiting the PI3K/AKT signaling pathway, which may be related to the inhibition of HIF‑1α expression. These findings may have clinical significance for the treatment of oxaliplatin‑resistant liver cancer.

Keywords:  LY‑294002; MK‑2206; PI3K/AKT; hepatocellular carcinoma; hypoxia inducible factor‑1α; oxaliplatin

DOI:  https://doi.org/10.3892/mmr.2021.12147
Exp Ther Med. 2021 Jun;21(6): 646

Hypoxia-inducible factor-1α regulates PI3K/AKT signaling through microRNA-32-5p/PTEN and affects nucleus pulposus cell proliferation and apoptosis.

Daolu Zhan, Mingxia Lin, Jian Chen, Wentao Cai, Jian Liu, Yehan Fang, Yibo Li, Bin Wu, Guangji Wang.

  Intervertebral disc degeneration and resulting low back pain arises from the programmed apoptosis of nucleus pulposus cells (NPCs). Recent studies show that hypoxia-inducible factor-1α plays a vital role in the etiology and pathogenesis of disc degeneration. However, the underlying mechanism of HIF-1α in NPCs is unclear. The present study identified 994 significant differentially expressed miRNAs by analyzing microarray data downloaded from the Gene Expression Omnibus database. MicroRNA(miR)-32-5p expression was 2.81-fold upregulated in NPCs compared with that of the healthy control tissues (P<0.05). A total of 331 significant differentially expressed mRNAs were identified, and PTEN was downregulated in NPCs of non-degenerative disc tissues from young patients. miR-32-5p was predicted to target the PTEN 3'-untranslated region (UTR). To confirm these results, in-vitro experiments investigating the molecular function of miR-32-5p and PTEN were performed. Furthermore, hypoxia induced miR-32-5p and PTEN expression. HIF-1α inhibited NPC proliferation and promoted cell apoptosis by regulating miR-32-5p and PTEN. miR-32-5p promoted NPC proliferation and decreased cell apoptosis. Next, it was verified whether miR-32-5p targeted the PTEN 3'-UTR using dual-luciferase reporter assays. Finally, it was observed that PI3K/AKT/mTOR signaling pathway was upregulated by a miR-32-5p mimic, which improved cell proliferation and decreased apoptosis. Importantly, PTEN was downregulated in these experiments; and inhibition of miR-32-5p had the opposite effect. Overall, these results demonstrate that HIF-1α regulates cell proliferation and apoptosis by controlling the miR-32-5p/PTEN/PI3K/AKT/mTOR axis in NPCs.

Keywords:  PI3K/AKT/mTOR signaling pathway; PTEN; hypoxia-inducible factor-1α; microRNA-32-5p; nucleus pulposus cells

DOI:  https://doi.org/10.3892/etm.2021.10078
J Gastroenterol Hepatol. 2021 May 12.

TFB2M activates aerobic glycolysis in hepatocellular carcinoma cells through the NAD+ /SIRT3/HIF-1α signaling.

Hulin Chang, Jibin Li, Ying Luo, Bing Wu, Chong Yuan, Xilin Geng.

  BACKGROUND: Increased aerobic glycolysis has been well-known as a hallmark of cancer, which is closely related to mitochondrial dysfunction. TFB2M (mitochondrial transcription factor B2) is a core mitochondrial transcription factor, which has been shown by us to play an oncogenic role in hepatocellular carcinoma (HCC). However, whether TFB2M contributes to the aerobic glycolysis in HCC cells remains unexplored.METHODS: The role and underlying molecular mechanisms of TFB2M in the regulation of aerobic glycolysis in HCC cells were systematically investigated by in vitro cell glucose metabolism and metabolomics analyses. Besides, the effects of TFB2M-regulated aerobic glycolysis in the growth and metastasis of HCC cells were also explored.
RESULTS: Here, we show that TFB2M markedly enhanced the reprogramming of glucose metabolism from oxidative phosphorylation to aerobic glycolysis mainly through two mechanisms. On the one hand, TFB2M increased the expressions of glycolytic genes GAPDH, LDHA, GLUT1 and HK2. On the other hand, TFB2M decreased the expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), a critical regulator of mitochondrial respiration. Mechanistically, TFB2M regulates the up-regulation of glycolytic genes and down-regulation of PGC-1α mainly through NAD+ /SIRT3/HIF-1α signaling. Additionally, we found that TFBM2 promoted the progression of HCC cells through HIF-1α-regulated reprogramming of glucose metabolism.
CONCLUSIONS: Our findings indicate that TFB2M serves as a critical glucose metabolic reprogramming mechanism in tumorigenesis, which could be used as potential therapeutic target in HCC.

Keywords:  HIF-1α; glycolysis; hepatocellular carcinoma; mitochondrial transcription factor B2; sirtuin 3

DOI:  https://doi.org/10.1111/jgh.15548
J Bioenerg Biomembr. 2021 May 10.

Hypoxia-induced HIF1α dependent COX2 promotes ovarian cancer progress.

Yumei Ding, Shichao Zhuang, Yujiao Li, Xiaohui Yu, Ming Lu, Ning Ding.

  Hypoxia can promote the progression and metastasis of ovarian cancer, while the underlying mechanisms are still unclear. Hypoxia culture or CoCl2 induced-oxygen deprivation condition could promote SKOV3 cells to express cyclooxygenase-2 (COX2). Luciferase assay indicates that hypoxia-inducible factor 1α (HIF1α) could bind directly with the promoter region of COX2 to promote the transcription. COX2 over-expressed SKOV3 cells show up-regulated stemness-related markers expression, proinflammatory gene expression, and increased tumor sphere formation. The inflammatory molecules (interleukin-6, C-X-C motif chemokine ligand 12, interleukin-1B, interleukin-10, and C-C motif chemokine ligand 2) and COX2 expression show positive correlations in the Cancer Genome Atlas data. COX2 over-expression could promote SKOV3 cell proliferation in the subcutaneous tumor model and metastasis in the transfer model. In conclusion, hypoxia-induced HIF-1α mediated COX2 expression could promote the proliferation, inflammation, and metastasis of ovarian cancer.

Keywords:  COX2; HIF1α; Hypoxia; Ovarian cancer; Proinflammatory cytokines

DOI:  https://doi.org/10.1007/s10863-021-09900-9
Sci Rep. 2021 May 14. 11(1): 10325

Effect of hypoxia factors gene silencing on ROS production and metabolic status of A375 malignant melanoma cells.

Ivana Špaková, Miroslava Rabajdová, Helena Mičková, Wolfgang F Graier, Mária Mareková.

The innate response of melanocytes to exogenous or endogenous stress stimuli like extreme pH and temperature, metabolite and oxygen deficiency or a high UV dose initiates a cellular stress response. This process activates adaptive processes to minimize the negative impact of the stressor on the pigment cell. Under physiological conditions, a non-cancer cell is directed to apoptosis if the stressor persists. However, malignant melanoma cells will survive persistent stress thanks to distinct "cancerous" signaling pathways (e.g. MEK) and transcription factors that regulate the expression of so-called "survival genes" (e.g. HIF, MITF). In this survival response of cancer cells, MEK pathway directs melanoma cells to deregulate mitochondrial metabolism, to accumulate reduced species (NADH), and to centralize metabolism in the cytosol. The aim of this work was to study the effect of gene silencing in malignant melanoma A375 cells on metabolic processes in cytosol and mitochondria. Gene silencing of HIF-1α, and miR-210 in normoxia and pseudohypoxia, and analysis of its effect on MITF-M, and PDHA1 expression. Detection of cytosolic NADH by Peredox-mCherry Assay. Detection of OCR, and ECAR using Seahorse XF96. Measurement of produced O2•- with MitoTracker Red CMXRos. 1H NMR analysis of metabolites present in cell suspension, and medium. By gene silencing of HIF-1α and miR-210 the expression of PDHA1 was upregulated while that of MITF-M was downregulated, yielding acceleration of mitochondrial respiratory activity and thus elimination of ROS. Hence, we detected a significantly reduced A375 cell viability, an increase in alanine, inositol, nucleotides, and other metabolites that together define apoptosis. Based on the results of measurements of mitochondrial resipiratory activity, ROS production, and changes in the metabolites obtained in cells under the observed conditions, we concluded that silencing of HIF-1α and miR-210 yields apoptosis and, ultimately, apoptotic cell death in A375 melanoma cells.

DOI: https://doi.org/10.1038/s41598-021-89792-2
PLoS Pathog. 2021 May 14. 17(5): e1009597

STING regulates metabolic reprogramming in macrophages via HIF-1α during Brucella infection.

Marco Tulio R Gomes, Erika S Guimarães, Fabio V Marinho, Isabella Macedo, Eric R G R Aguiar, Glen N Barber, Pedro M M Moraes-Vieira, José Carlos Alves-Filho, Sergio C Oliveira.

Macrophages metabolic reprogramming in response to microbial insults is a major determinant of pathogen growth or containment. Here, we reveal a distinct mechanism by which stimulator of interferon genes (STING), a cytosolic sensor that regulates innate immune responses, contributes to an inflammatory M1-like macrophage profile upon Brucella abortus infection. This metabolic reprogramming is induced by STING-dependent stabilization of hypoxia-inducible factor-1 alpha (HIF-1α), a global regulator of cellular metabolism and innate immune cell functions. HIF-1α stabilization reduces oxidative phosphorylation and increases glycolysis during infection with B. abortus and, likewise, enhances nitric oxide production, inflammasome activation and IL-1β release in infected macrophages. Furthermore, the induction of this inflammatory profile participates in the control of bacterial replication since absence of HIF-1α renders mice more susceptible to B. abortus infection. Mechanistically, activation of STING by B. abortus infection drives the production of mitochondrial reactive oxygen species (mROS) that ultimately influences HIF-1α stabilization. Moreover, STING increases the intracellular succinate concentration in infected macrophages, and succinate pretreatment induces HIF-1α stabilization and IL-1β release independently of its cognate receptor GPR91. Collectively, these data demonstrate a pivotal mechanism in the immunometabolic regulation of macrophages during B. abortus infection that is orchestrated by STING via HIF-1α pathway and highlight the metabolic reprogramming of macrophages as a potential treatment strategy for bacterial infections.

DOI: https://doi.org/10.1371/journal.ppat.1009597
Mater Sci Eng C Mater Biol Appl. 2021 Jun;pii: S0928-4931(21)00242-3. [Epub ahead of print]125 112103

Improved delivery system for celastrol-loaded magnetic Fe3O4/α-Fe2O3 heterogeneous nanorods: HIF-1α-related apoptotic effects on SMMC-7721 cell.

Ruijiang Liu, Zhixiang Lv, Xiao Liu, Wei Huang, Shuai Pan, Ruitong Yin, Lulu Yu, You Li, Yanling Zhang, Shaoshuai Zhang, Rongzhu Lu, Yongjin Li, Shasha Li.

  Fe3O4/α-Fe2O3 heterogeneous nanorods were prepared by a rapid combustion method with α-FeOOH nanorods as precursors. Fe3O4/α-Fe2O3 heterogeneous nanorods with a saturation magnetization of 33.2 emu·g-1 were obtained using 30 mL of absolute ethanol at a calcination temperature of 300 °C. Their average length was around 140 nm, and average diameter was about 20 nm. To improve the dispersion characteristics of the Fe3O4/α-Fe2O3 heterogeneous nanorods in aqueous solution, citric acid and PEG were applied to modify the nanorod surface via the Mitsunobu reaction. The results showed that the hydrodynamic size range of Fe3O4/α-Fe2O3/CA-PEG-celastrol was 250-500 nm, the surface potential was -15 mV, and the saturation magnetization was approximately 23 emu·g-1. The drug loading capacity of Fe3O4/α-Fe2O3/CA-PEG was larger than the non-PEG modified version. Fe3O4/α-Fe2O3/CA-PEG-celastrol had slow-release characteristics and was sensitive to changes in pH. Application of a magnetic field significantly promoted the inhibition of SMMC-7721 human liver cancer cell growth after treatment with Fe3O4/α-Fe2O3/CA-PEG-celastrol. Celastrol and Fe3O4/α-Fe2O3/CA-PEG-celastrol increased the production of reactive oxygen species in SMMC-7721 cells and promoted apoptosis and apoptosis-related proteins (p53, Bax, Bcl-2) were also changed. In addition, the expression of hypoxia-inducible factor 1α (HIF-1α) was enhanced. We may conclude that celastrol-loaded magnetic Fe3O4/α-Fe2O3 heterogeneous nanorods may be applied in the chemotherapy of human cancer with good biocompatibility and delivery.

Keywords:  Apoptosis; Celastrol; HIF-1α; Liver cancer; Magnetic Fe(3)O(4)/α-Fe(2)O(3) heterogeneous nanorods; Reactive oxygen species

DOI:  https://doi.org/10.1016/j.msec.2021.112103
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2021 Apr 28. pii: 1672-7347(2021)04-0333-12. [Epub ahead of print]46(4): 333-344

HIF-1α may promote glycolysis in psoriasis vulgaris via upregulation of CD147 and GLUT1.

Wen Tang, Tingting Long, Fangfang Li, Cong Peng, Shuang Zhao, Xiang Chen, Juan Su.

  OBJECTIVES: To analyze the expressions and distributions of hypoxia-inducible factor-1α (HIF-1α), CD147, and glucose transporter 1 (GLUT1) in epidermis from psoriasis vulgaris and normal people, and to explore the associations among these proteins and their roles in hypoxic HaCaT cell line.METHODS: The expression levels of HIF-1α, CD147, and GLUT1 were determined by immunohistochemistry staining in skin biopsies from 48 psoriasis vularis patients and 33 healthy subjects. Cobalt chloride (CoCl2) was added into the culture media of HaCaT cells to mimic hypoxia while RNA interference and transfection technologies were used to explore the association among these proteins by quantitative real-time polymerase chain reaction and Western blotting. Glycolytic capacity was detected by ATP and lactate measurements.
RESULTS: HIF-1α, CD147, and GLUT1 were highly expressed and the glycolytic capacity was increased in lesions of psoriasis vulgaris; HIF-1α upregulated the expression of CD147 and GLUT1, increased the lactate production and decreased the ATP level in CoCl2-treated HaCaT cells, while CD147 and GLUT1 directly or indirectly bound to each other.
CONCLUSIONS: Glycolytic capacity increases in the injured keratinocytes of psoriasis vulgaris, suggesting that HIF-1α, CD147, and GLUT1 are associated with glycolysis, which can be considered as the promising targets for psoriasis therapy.

Keywords:  CD147; glucose transporter 1; glycolysis; hypoxia-inducible factor-1α; psoriasis

DOI:  https://doi.org/10.11817/j.issn.1672-7347.2021.200010
PeerJ. 2021 ;9 e11275

Downregulation of both mismatch repair and non-homologous end-joining pathways in hypoxic brain tumour cell lines.

Sophie Cowman, Barry Pizer, Violaine Sée.

  Glioblastoma, a grade IV astrocytoma, has a poor survival rate in part due to ineffective treatment options available. These tumours are heterogeneous with areas of low oxygen levels, termed hypoxic regions. Many intra-cellular signalling pathways, including DNA repair, can be altered by hypoxia. Since DNA damage induction and subsequent activation of DNA repair mechanisms is the cornerstone of glioblastoma treatment, alterations to DNA repair mechanisms could have a direct influence on treatment success. Our aim was to elucidate the impact of chronic hypoxia on DNA repair gene expression in a range of glioblastoma cell lines. We adopted a NanoString transcriptomic approach to examine the expression of 180 DNA repair-related genes in four classical glioblastoma cell lines (U87-MG, U251-MG, D566-MG, T98G) exposed to 5 days of normoxia (21% O2), moderate (1% O2) or severe (0.1% O2) hypoxia. We observed altered gene expression in several DNA repair pathways including homologous recombination repair, non-homologous end-joining and mismatch repair, with hypoxia primarily resulting in downregulation of gene expression. The extent of gene expression changes was dependent on hypoxic severity. Some, but not all, of these downregulations were directly under the control of HIF activity. For example, the downregulation of LIG4, a key component of non-homologous end-joining, was reversed upon inhibition of the hypoxia-inducible factor (HIF). In contrast, the downregulation of the mismatch repair gene, PMS2, was not affected by HIF inhibition. This suggests that numerous molecular mechanisms lead to hypoxia-induced reprogramming of the transcriptional landscape of DNA repair. Whilst the global impact of hypoxia on DNA repair gene expression is likely to lead to genomic instability, tumorigenesis and reduced sensitivity to anti-cancer treatment, treatment re-sensitising might require additional approaches to a simple HIF inhibition.

Keywords:  DNA Ligase IV; DNA repair; Glioblastoma; HIF inhibition; Hypoxia; Mismatch repair; NanoString; Non-homologous end-joining; PMS2

DOI:  https://doi.org/10.7717/peerj.11275
Sci Rep. 2021 May 10. 11(1): 9892

Endoplasmic reticulum stress regulates the intestinal stem cell state through CtBP2.

Bartolomeus J Meijer, Wouter L Smit, Pim J Koelink, Barbara F Westendorp, Ruben J de Boer, Jonathan H M van der Meer, Jacqueline L M Vermeulen, James C Paton, Adrienne W Paton, Jun Qin, Evelien Dekker, Vanesa Muncan, Gijs R van den Brink, Jarom Heijmans.

Enforcing differentiation of cancer stem cells is considered as a potential strategy to sensitize colorectal cancer cells to irradiation and chemotherapy. Activation of the unfolded protein response, due to endoplasmic reticulum (ER) stress, causes rapid stem cell differentiation in normal intestinal and colon cancer cells. We previously found that stem cell differentiation was mediated by a Protein kinase R-like ER kinase (PERK) dependent arrest of mRNA translation, resulting in rapid protein depletion of WNT-dependent transcription factor c-MYC. We hypothesize that ER stress dependent stem cell differentiation may rely on the depletion of additional transcriptional regulators with a short protein half-life that are rapidly depleted due to a PERK-dependent translational pause. Using a novel screening method, we identify novel transcription factors that regulate the intestinal stem cell fate upon ER stress. ER stress was induced in LS174T cells with thapsigargin or subtilase cytotoxin (SubAB) and immediate alterations in nuclear transcription factor activity were assessed by the CatTFRE assay in which transcription factors present in nuclear lysate are bound to plasmid DNA, co-extracted and quantified using mass-spectrometry. The role of altered activity of transcription factor CtBP2 was further examined by modification of its expression levels using CAG-rtTA3-CtBP2 overexpression in small intestinal organoids, shCtBP2 knockdown in LS174T cells, and familial adenomatous polyposis patient-derived organoids. CtBP2 overexpression organoids were challenged by ER stress and ionizing irradiation. We identified a unique set of transcription factors with altered activation upon ER stress. Gene ontology analysis showed that transcription factors with diminished binding were involved in cellular differentiation processes. ER stress decreased CtBP2 protein expression in mouse small intestine. ER stress induced loss of CtBP2 expression which was rescued by inhibition of PERK signaling. CtBP2 was overexpressed in mouse and human colorectal adenomas. Inducible CtBP2 overexpression in organoids conferred higher clonogenic potential, resilience to irradiation-induced damage and a partial rescue of ER stress-induced loss of stemness. Using an unbiased proteomics approach, we identified a unique set of transcription factors for which DNA-binding activity is lost directly upon ER stress. We continued investigating the function of co-regulator CtBP2, and show that CtBP2 mediates ER stress-induced loss of stemness which supports the intestinal stem cell state in homeostatic stem cells and colorectal cancer cells.

DOI: https://doi.org/10.1038/s41598-021-89326-w
Fitoterapia. 2021 May 10. pii: S0367-326X(21)00097-6. [Epub ahead of print] 104922

Cynaroside prevents macrophage polarization into pro-inflammatory phenotype and alleviates cecal ligation and puncture-induced liver injury by targeting PKM2/HIF-1α axis.

Liuhua Pei, Yifei Le, Hang Chen, Jiafan Feng, Zhijun Liu, Ji Zhu, Cui Wang, Lin Chen, Xiaobing Dou, Dezhao Lu.

  The treatment of sepsis is still challenging and the liver is an important target of sepsis-related injury. Macrophages are important innate immune cells in liver, and modulation of macrophages M1/M2 polarization may be a promising strategy for septic liver injury treatment. Macrophage polarization and inflammation of liver tissue has been shown regulated by pyruvate kinase M2 (PKM2)-mediated aerobic glycolysis and immune inflammatory pathways. Therefore, modulating PKM2-mediated immunometabolic reprogramming presents a novel strategy for inflammation-associated diseases. In this study, cynaroside, a flavonoid compound, promoted macrophage phenotypic transition from pro-inflammatory M1 to anti-inflammatory M2, and mitigated sepsis-associated liver inflammatory damage. We established that cynaroside reduced binding of PKM2 to hypoxia-inducible factor-1α (HIF-1α) by abolishing translocation of PKM2 to the nucleus and promoting PKM2 tetramer formation, as well as suppressing phosphorylation of PKM2 at Y105 in vivo and in vitro. Moreover, cynaroside restored pyruvate kinase activity, inhibited glycolysis-related proteins including PFKFB3, HK2 and HIF-1α, and inhibited glycolysis-related hyperacetylation of HMGB1 in septic liver. Therefore, this study reports a novel function of cynaroside in hepatic macrophage polarization, and cecum ligation and puncture-induced liver injury in septic mice. The findings provide crucial information with regard to therapeutic efficacy of cynaroside in the treatment of sepsis.

Keywords:  HMGB1; Liver injury; Macrophage polarization; PKM2; Sepsis

DOI:  https://doi.org/10.1016/j.fitote.2021.104922
J Exp Clin Cancer Res. 2021 May 08. 40(1): 159

Hypoxia-dependent drivers of melanoma progression.

Simona D'Aguanno, Fabiana Mallone, Marco Marenco, Donatella Del Bufalo, Antonietta Moramarco.

  Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.

Keywords:  Angiogenesis; Cutaneous melanoma (CM); HIF-1; Hypoxia; Mucosal melanoma (MM); Uveal melanoma (UM); Vasculogenic mimicry

DOI:  https://doi.org/10.1186/s13046-021-01926-6
Rinsho Ketsueki. 2021 ;62(4): 305-313

[Identification of hypoxia-specific therapeutic targets in multiple myeloma].

Sho Ikeda.

  The bone marrow microenvironment is low in oxygen, promoting a hypoxic response which causes myeloma cells to acquire stem cell properties and enhanced therapy resistance. We performed comprehensive gene and microRNA expression analyses of samples from myeloma patients and cell lines cultured under hypoxia. Through this, we identified the histone demethylase KDM3A, the glycolytic enzyme HK2, and microRNA-210 as factors playing important roles in the behavior of cells under hypoxic conditions. These genes were regulated by the hypoxia-inducible factor HIF. However, we also found that the expression of IRF4 and MYC, factors required for maintenance of differentiation and proliferation was suppressed by hypoxia. This suggests that the regulatory factors that induce drug resistance and the anti-apoptotic capacity of myeloma cells fluctuate with the partial pressure of oxygen in their environment. Based on this premise, a dual treatment strategy in which a dominant clone and a dormant clone adapted to the hypoxic microenvironment are treated simultaneously with orthogonal drugs is a potentially viable strategy to achieve a cure for multiple myeloma.

Keywords:  HIF; Hypoxia; Multiple myeloma; Plasticity

DOI:  https://doi.org/10.11406/rinketsu.62.305
DNA Cell Biol. 2021 May 14.

The Role of Autophagy in Hypoxia-Induced Neuroinflammation.

Sha Sha, Jin Tan, Yuyang Miao, Qiang Zhang.

  Autophagy is a critical cytoprotective mechanism that takes a hand in innate or adaptive immune responses. Hypoxia is a common pathophysiological mechanism that can lead to systemic pathological reactions. In recent years, the impact of hypoxia on the central nervous system has attracted more attention. In the past, autophagy was thought to be directly involved in the apoptosis of nerve cells under hypoxia. An increasing amount of evidence shows that the neuroinflammatory response plays an indispensable role in the neural damage caused by hypoxia. There are many mechanisms related to the neuroinflammatory response induced by hypoxia, among which autophagy is an important aspect, but the role of autophagy is still unclear. This article focuses on how autophagy flux of central immune cells is modified under hypoxic conditions, and how this autophagy affects neuroinflammatory response.

Keywords:  inflammation; inflammatory factors; microglia; signaling pathway

DOI:  https://doi.org/10.1089/dna.2020.6186
mSystems. 2021 May 11. pii: e00163-21. [Epub ahead of print]6(3):

Oral Epithelial Cells Distinguish between Candida Species with High or Low Pathogenic Potential through MicroRNA Regulation.

Márton Horváth, Gábor Nagy, Nóra Zsindely, László Bodai, Péter Horváth, Csaba Vágvölgyi, Joshua D Nosanchuk, Renáta Tóth, Attila Gácser.

  Oral epithelial cells monitor microbiome composition and initiate immune response upon dysbiosis, as in the case of Candida imbalances. Candida species, such as C. albicans and C. parapsilosis, are the most prevalent yeasts in the oral cavity. Comparison of healthy oral epithelial cell responses revealed that while C. albicans infection robustly activated inflammation cascades, C. parapsilosis primarily activated various inflammation-independent pathways. In posttranscriptional regulatory processes, several miRNAs were altered by both species. For C. parapsilosis, the dose of yeast cells directly correlated with changes in transcriptomic responses with higher fungal burdens inducing significantly different and broader changes. MicroRNAs (miRNAs) associated with carbohydrate metabolism-, hypoxia-, and vascular development-related responses dominated with C. parapsilosis infection, whereas C. albicans altered miRNAs linked to inflammatory responses. Subsequent analyses of hypoxia-inducible factor 1α (HIF1-α) and hepatic stellate cell (HSC) activation pathways predicted target genes through which miRNA-dependent regulation of yeast-specific functions may occur, which also supported the observed species-specific responses. Our findings suggest that C. parapsilosis is recognized as a commensal at low doses by the oral epithelium; however, increased fungal burden activates different pathways, some of which overlap with the inflammatory processes robustly induced by C. albicans IMPORTANCE A relatively new topic within the field of immunology involves the role of miRNAs in innate as well as adaptive immune response regulation. In recent years, posttranscriptional regulation of host-pathogenic fungal interactions through miRNAs was also suggested. Our study reveals that the distinct nature of human oral epithelial cell responses toward C. parapsilosis and C. albicans is possibly due to species-specific fine-tuning of host miRNA regulatory processes. The findings of this study also shed new light on the nature of early host cell transcriptional responses to the presence of C. parapsilosis and highlight the species' potential inflammation-independent host activation processes. These findings contribute to our better understanding of how miRNA deregulation at the oral immunological barrier, in noncanonical immune cells, may discriminate between fungal species, particularly Candida species with high or low pathogenic potential.

Keywords:  Candida; host-pathogen interaction; miRNA regulation; oral epithelial cell

DOI:  https://doi.org/10.1128/mSystems.00163-21
Ren Fail. 2021 Dec;43(1): 803-810

Hypoxia-inducible factor prolyl hydroxylase inhibitor roxadustat (FG-4592) protects against renal ischemia/reperfusion injury by inhibiting inflammation.

A-Feng Miao, Jian-Xiang Liang, Lei Yao, Jun-Ling Han, Li-Juan Zhou.

  Hypoxia-induced inflammation is the critical pathological feature of acute kidney injury (AKI). Activation of hypoxia-inducible factor (HIF) signaling is considered as a central mechanism of body adapting to hypoxia. Hypoxia-inducible factor prolyl hydroxylase inhibitor FG-4592 (Roxadustat) is a first-in-class HIF stabilizer for the treatment of patients with renal anemia. The current study aimed to investigate whether FG-4592 could protect against ischemia/reperfusion (I/R)-induced kidney injury via inhibiting inflammation. Here, efficacy of FG-4592 was evaluated in a mice model of I/R-induced AKI. Interestingly, improved renal function and renal tubular injuries, combined with reduced kidney injury molecule-1 were observed in the mice with FG-4592 administration. Meanwhile, inflammation responses in FG-4592-treated mice were also strikingly attenuated, as evidenced by the decreased infiltration of macrophages and neutrophils and down-regulated expression of inflammatory cytokines. In vitro, FG-4592 treatment significantly protected the tubular epithelial cells against hypoxia-induced injury, with suppressed inflammation and cell injuries. In summary, FG-4592 treatment could protect against the I/R-induced kidney injury possibly through diminishing tubular cells injuries and suppression of sequence inflammatory responses. Thus, our findings definitely offered a clinical potential approach in treating AKI.

Keywords:  FG-4592; inflammation; renal ischemia/reperfusion injury

DOI:  https://doi.org/10.1080/0886022X.2021.1915801
Gene. 2021 May 05. pii: S0378-1119(21)00289-4. [Epub ahead of print] 145695

Hypoxia-induced retinal pigment epithelium cell-derived bFGF promotes the migration and angiogenesis of HUVECs through regulating TGF-β1/smad2/3 pathway.

Wensi Chen, Shiping He, Daoman Xiang.

  Hypoxia promotes the secretion of basic fibroblast growth factor (bFGF) in retinal pigment epithelium (RPE), which plays an important part in retinopathy of prematurity (ROP). This study preliminarily explored the effect of hypoxia-induced RPE-derived bFGF on the biological functions of human umbilical vein endothelial cells (HUVECs). After cell culture in hypoxia conditions, the cell viability, apoptosis, and the expressions of bFGF and vascular endothelial growth factor A (VEGFA) in human RPEs were detected by 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, Western blot, RT-qPCR, or ELISA. The HUVECs were transfected with siRNA for bFGF (sibFGF) or transforming growth factor-β1 (TGF-β1) (siTGF-β1) and grown in the supernatant RPE under normoxia conditions or hypoxia conditions to further determine the cell viability, migration, angiogenesis, and the expressions of TGF-β1, p-smad2/3, and smad2/3 in the cells by performing MTT, transwell, tube formation, Western blot, or RT-qPCR. Hypoxia culture decreased the cell viability and promoted the apoptosis as well as the expressions of bFGF and VEGFA in RPEs. In both normoxia and hypoxia conditions, RPE-derived bFGF increased the cell viability, migration, angiogenesis, and the expressions of TGF-β1 and p-smad2/3 in the HUVECs, with hypoxia-induced RPE-derived bFGF showing a stronger effect than bFGF induced by normoxia. However, sibFGF reversed the effects caused by RPE-derived bFGF. Moreover, siTGF-β1 decreased the high cell viability, migration and angiogenesis of HUVECs, and downregulated the expressions of TGF-β1 and phosphorylated (p)-smad2/3 upregulated by hypoxia-induced RPE-derived bFGF. Hypoxia-induced RPE-derived bFGF could promote the migration and angiogenesis of HUVECs through regulating TGF-β1/smad2/3 pathway.

Keywords:  HUVECs; Hypoxia; bFGF; retinal pigment epithelium; retinopathy of prematurity

DOI:  https://doi.org/10.1016/j.gene.2021.145695
Cell Biosci. 2021 May 12. 11(1): 84

The YAP/HIF-1α/miR-182/EGR2 axis is implicated in asthma severity through the control of Th17 cell differentiation.

Jing Zhou, Ning Zhang, Wei Zhang, Caiju Lu, Fei Xu.

  BACKGROUND: Asthma is a heterogeneous chronic inflammatory disease of the airway, involving reversible airflow limitation and airway remodeling. T helper 17 (Th17) cells play an important role in the pathogenesis of allergic asthma. However, there is limited understanding of the signaling pathways controlling Th17 cell differentiation in asthma. The aim of this study was to investigate if the Yes-associated protein (YAP)/hypoxia inducible factor-1α (HIF-1α)/microRNA-182 (miR-182)/early growth response 2 (EGR2) axis is involved in mediating Th17 cell differentiation and disease severity in asthma.METHODS: The study included 29 pediatric patients with asthma, 22 healthy volunteers, ovalbumin-induced murine asthma models, and mouse naive CD4+ T cells. The subpopulation of Th17 cells was examined by flow cytometry. The levels of interleukin-17A were determined by enzyme linked immunosorbent assay. Chromatin immunoprecipitation-quantitative polymerase chain reaction assays and dual-luciferase reporter gene assays were performed to examine interactions between HIF-1α and miR-182, and between miR-182 and EGR2.
RESULTS: YAP, HIF-1α, and miR-182 were upregulated but EGR2 was downregulated in human and mouse peripheral blood mononuclear cells from the asthma group. Abundant expression of YAP and HIF-1α promoted miR-182 expression and then inhibited EGR2, a target of miR-182, thus enhancing Th17 differentiation and deteriorating asthma and lipid metabolism dysfunction. In addition, in vivo overexpression of EGR2 countered the promoting effect of the YAP/HIF-1α/miR-182 axis on asthma and lipid metabolism dysfunction.
CONCLUSION: These results indicate that activation of the YAP/HIF-1α/miR-182/EGR2 axis may promote Th17 cell differentiation, exacerbate asthma development, and aggravate lipid metabolism dysfunction, thus suggesting a potential therapeutic target for asthma.

Keywords:  Asthma; Differentiation; Dyslipidemia; EGR2; HIF-1α; MiR-182; Th17 cells; YAP

DOI:  https://doi.org/10.1186/s13578-021-00560-1
Cell Commun Signal. 2021 May 12. 19(1): 53

ATF5 and HIF1α cooperatively activate HIF1 signaling pathway in esophageal cancer.

Feng He, Hang Xiao, Yixin Cai, Ni Zhang.

  BACKGROUND: Esophageal cancer (ESCA) is one of the most common cancers worldwide and has a very poor prognosis. Hypoxia-inducible factor 1 (HIF1) signaling pathway plays a critical role in tumorigenesis and is therefore considered a potential therapeutic target in the treatment of many cancers. Activating transcription factor 5 (ATF5) facilitates the expression of various genes and has been extensively studied for its potential role in cancer treatment.METHODS: The expression level of ATF5 in clinic sample was detected by quantitative real time PCR and immunohistochemistry. ATF5 biological function was investigated by western blot, cell cycle analysis, cell viability assay, luciferase reporter assays, colony formation assay, transwell assay, wound healing assay, tube formation assay, and ELISA assay. CHIP and Re-CHIP assay, GST-pulldown, and RNA-sequencing were used to study the cross-talks between ATF5 and HIF1 complex. Mouse xenograft study was utilized to study the correlation of ATF5 and tumor growth in vivo. Student's t-test or Chi-square test was used for statistical analysis.
RESULTS: Here, we first found ATF5 was dramatically upregulated in ESCA cancer and related with poor survival time. Next, we found that the expression level of ATF5 had a positive relationship with the proliferation, migration, and invasion ability of ESCA cells. Besides, we innovatively found that ATF5 functions as a novel coactivator in HIF1 transcription complex by binding to HIF1α. Further, we demonstrated that silencing ATF5 phenocopies HIF1α knockdown in tumorigenic properties in vitro and inhibited ESCA tumor angiogenesis and proliferation in vivo.
CONCLUSION: Herein, we found ATF5 as a novel component of the HIF1 transcription complex. The findings of the present study may provide new insights into the development of a novel and more efficient therapeutic strategy against ESCA. Video abstract.

Keywords:  ATF5; Esophageal cancer; HIF1

DOI:  https://doi.org/10.1186/s12964-021-00734-x
Hepatology. 2021 May 15.

HIF1α-mediated RelB/APOBEC3B downregulation allows Hepatitis B Virus persistence.

Tobias Riedl, Suzanne Faure-Dupuy, Maude Rolland, Svenja Schuehle, Zohier Hizir, Silvia Calderazzo, Xiaodong Zhuang, Jochen Wettengel, Martin Alexander Lopez, Romain Barnault, Valbona Mirakaj, Sandra Prokosch, Danijela Heide, Corinna Leuchtenbergeg, Martin Schneider, Bernd Heßling, Benjamin Stottmeier, Isabel M Wessbecher, Peter Schirmacher, Jane A McKeating, Ulrike Protzer, David Durantel, Julie Lucifora, Emmanuel Dejardin, Mathias Heikenwalder.

  New therapeutic strategies against Hepatitis B virus (HBV) focus, among others, on the activation of the immune system to enable the infected host to eliminate HBV. Hypoxia inducible factor 1 alpha (HIF1α) stabilisation has been associated with impaired immune responses. HBV pathogenesis triggers chronic hepatitis-related scaring, leading inter alia to modulation of liver oxygenation and transient immune activation, both factors playing a role in HIF1α stabilisation. We addressed whether HIF1α interferes with immune-mediated induction of the cytidine deaminase APOBEC3B and subsequent covalently closed circular DNA (cccDNA) decay. Liver biopsies of chronic HBV patients (CHB) were analysed by IHC, and in situ hybridization. The effect of HIF1α induction/stabilisation on differentiated HepaRG or mice +/- HBV +/- LTβR-agonist (BS1) was assessed in vitro and in vivo. Induction of A3B and subsequent effects were analysed by RT-qPCR, immunoblotting, ChIP, ICC, and mass-spectrometry. Analysing CHB highlighted that areas with high HIF1α levels and low A3B expression correlated with high HBcAg, potentially representing a reservoir for HBV survival in immune-active patients. In vitro, HIF1α stabilisation, strongly impaired A3B expression and anti-HBV effect. Interestingly, HIF1α knock-down was sufficient to rescue the inhibition of A3B-upregulation and -mediated antiviral effects, whereas HIF2α knock-down had no effect. HIF1α stabilisation decreased the level of RelB protein but not its mRNA, which was confirmed in vivo. Noteworthy, this function of HIF1α was independent of its partner ARNT. In conclusion, inhibiting HIF1α expression or stabilisation represents a novel anti-HBV strategy in the context of immune-mediated A3B induction. High HIF1α, mediated by hypoxia or inflammation, offers a reservoir for HBV survival in vivo, and should be considered as a restricting factor in the development of novel immune therapies.

Keywords:  HIF1α; Hepatitis B virus; NF-κB; cccDNA; reservoir

DOI:  https://doi.org/10.1002/hep.31902