Hypoxia-inducible Factor Signaling Research Articles

The impact of hypoxia-inducible factors in the pathogenesis of kidney diseases: a link through cell metabolism.

Kidneys are sensitive to disturbances in oxygen homeostasis. Hypoxia and activation of the hypoxia-inducible factor (HIF) pathway alter the expression of genes involved in the metabolism of renal and immune cells, interfering with their functioning. Whether the transcriptional activity of HIF protects the kidneys or participates in the pathogenesis of renal diseases is unclear. Several studies have indicated that HIF signaling promotes fibrosis in experimental models of kidney disease. Other reports showed a protective effect of HIF activation on kidney inflammation and injury. In addition to the direct effect of HIF on the kidneys, experimental evidence indicates that HIF-mediated metabolic shift activates inflammatory cells, supporting the HIF cascade as a link between lung or gut damage and worsening of renal disease. Although hypoxia and HIF activation are present in several scenarios of renal diseases, further investigations are needed to clarify whether interfering with the HIF pathway is beneficial in different pathological contexts.

Mechanism of Xuebijing Injection in treatment of sepsis-associated ARDS based on network pharmacology and in vitro experiment

The aim of this study was to investigate the effect and molecular mechanism of Xuebijing Injection in the treatment of sepsis-associated acute respiratory distress syndrome(ARDS) based on network pharmacology and in vitro experiment. The active components of Xuebijing Injection were screened and the targets were predicted by the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP). The targets of sepsis-associated ARDS were searched against GeneCards, DisGeNet, OMIM, and TTD. Weishengxin platform was used to map the targets of the main active components in Xuebijing Injection and the targets of sepsis-associated ARDS, and Venn diagram was established to identify the common targets. Cytoscape 3.9.1 was used to build the "drug-active components-common targets-disease" network. The common targets were imported into STRING for the building of the protein-protein interaction(PPI) network, which was then imported into Cytoscape 3.9.1 for visualization. DAVID 6.8 was used for Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment of the common targets, and then Weishe-ngxin platform was used for visualization of the enrichment results. The top 20 KEGG signaling pathways were selected and imported into Cytoscape 3.9.1 to establish the KEGG network. Finally, molecular docking and in vitro cell experiment were performed to verify the prediction results. A total of 115 active components and 217 targets of Xuebijing Injection and 360 targets of sepsis-associated ARDS were obtained, among which 63 common targets were shared by Xuebijing Injection and the disease. The core targets included interleukin-1 beta(IL-1β), IL-6, albumin(ALB), serine/threonine-protein kinase(AKT1), and vascular endothelial growth factor A(VEGFA). A total of 453 GO terms were annotated, including 361 terms of biological processes(BP), 33 terms of cellular components(CC), and 59 terms of molecular functions(MF). The terms mainly involved cellular response to lipopolysaccharide, negative regulation of apoptotic process, lipopolysaccharide-mediated signaling pathway, positive regulation of transcription from RNA polyme-rase Ⅱ promoter, response to hypoxia, and inflammatory response. The KEGG enrichment revealed 85 pathways. After diseases and generalized pathways were eliminated, hypoxia-inducible factor-1(HIF-1), tumor necrosis factor(TNF), nuclear factor-kappa B(NF-κB), Toll-like receptor, and NOD-like receptor signaling pathways were screened out. Molecular docking showed that the main active components of Xuebijing Injection had good binding activity with the core targets. The in vitro experiment confirmed that Xuebijing Injection suppressed the HIF-1, TNF, NF-κB, Toll-like receptor, and NOD-like receptor signaling pathways, inhibited cell apoptosis and reactive oxygen species generation, and down-regulated the expression of TNF-α, IL-1β, and IL-6 in cells. In conclusion, Xuebijing Injection can regulate apoptosis and response to inflammation and oxidative stress by acting on HIF-1, TNF, NF-κB, Toll-like receptor, and NOD-like receptor signaling pathways to treat sepsis-associated ARDS.

Phase 2 study of batiraxcept (AVB-S6-500, an AXL inhibitor) as monotherapy, in combination with cabozantinib (cabo), and in combination with cabo and nivolumab (nivo) in patients with advanced clear cell renal cell carcinoma (ccRCC).

4534 Background: AXL is up-regulated by hypoxia-inducible factor-1 signaling in VHL-deficient tumor cells, playing a critical role in metastasis and resistance to VEGF-targeted therapies. Batiraxcept is a recombinant fusion protein containing an extracellular region of AXL combined with the human immunoglobulin G1 heavy chain (Fc), demonstrating potent and specific AXL inhibition through competitive binding of its ligand GAS6. A prior Phase 1b study showed promising outcomes for batiraxcept + cabo combination in patients who had failed first line (1L) therapy. Methods: This trial tested batiraxcept 15 mg/kg every 2 weeks (q2w) in 3 cohorts of ccRCC patients: 1) batiraxcept monotherapy (n=10) in patients with relapsing disease and no curative options; 2) batiraxcept + cabo 60 mg daily (QD) in patients with at least 1 prior therapy (n=25); and 3) batiraxcept + cabo 40 mg QD and nivo 240 q2w or 480 mg q4w in 1L (n=11). Primary endpoint was investigator assessed objective response rate (ORR) by RECIST v1.1, and key secondary endpoints were safety, progression free survival (PFS), and overall survival. Results: Enrollment has completed as of 17-January-2023. In the 3 cohorts, IMDC intermediate + poor risk was 80%, 76%, and 27%, and median prior lines of therapy were 4, 2, 0. Prior immunotherapy (IO) was received by 100%, 88%, and 0% patients. One hundred percent of patients receiving monotherapy and 40% of 2L patients receiving batiraxcept + cabo had received prior VEGF-TKIs. We describe efficacy and safety across the 3 cohorts. Conclusions: Batiraxcept monotherapy was well tolerated but had limited clinical activity. Batiraxcept-based combinations demonstrated efficacy and tolerability. Given encouraging safety and efficacy signals, batiraxcept + cabo will be further studied in a phase 3 trial of 2L+ ccRCC patients whose disease has progressed on prior IO and VEGF-TKI treatment. Exploratory analysis for a baseline serum soluble AXL/GAS6 ratio biomarker was found to have predictability for clinical activity in the phase 1b study evaluating batiraxcept + cabo in patients who had failed 1L therapies; a similar analysis using the biomarker is ongoing for this patient population. Clinical trial information: NCT04300140 . [Table: see text]

Butein, a potential drug for the treatment of bone cancer pain through bioinformatic and network pharmacology

Bone cancer pain is a difficult-to-treat pathologic condition that impairs the patient's quality of life. The effective therapy options for BCP are restricted due to the unknown pathophysiology. Transcriptome data were obtained from the Gene Expression Omnibus database and differentially expressed gene extraction was performed. DEGs integrated with pathological targets found 68 genes in the study. Butein was discovered as a possible medication for BCP after the 68 genes were submitted to the Connectivity Map 2.0 database for drug prediction. Moreover, butein has good drug-likeness properties. To collect the butein targets, we used the CTD, SEA, TargetNet, and Super-PRED databases. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed butein's pharmacological effects, indicating that butein may aid in treating BCP by altering the hypoxia-inducible factor, NF-kappa B, angiogenesis, and sphingolipid signaling pathways. Moreover, the pathological targets integrated with drug targets were obtained as the shared gene set A, which was analyzed by ClueGO and MCODE. Biological process analysis and MCODE algorithm further analyzed that BCP related targets were mainly involved in signal transduction process and ion channel-related pathways. Next, we integrated targets related to network topology parameters and targets of core pathways, identified PTGS2, EGFR, JUN, ESR1, TRPV1, AKT1 and VEGFA as butein regulated hub genes by molecular docking, which play a critical role in its analgesic effect. This study lays the scientific groundwork for elucidating the mechanism underlying butein's success in the treatment of BCP.

VBP1 negatively regulates CHIP and selectively inhibits the activity of hypoxia-inducible factor (HIF)-1α but not HIF-2α

Hypoxia-inducible factor-1 (HIF-1) is a critical transcription factor that regulates the expression of genes involved in cellular adaptation to low oxygen levels. Aberrant regulation of the HIF-1 signaling pathway is linked to various human diseases. Previous studies have established that HIF-1α is rapidly degraded in a von Hippel-Lindau protein (pVHL)-dependent manner under normoxic conditions. In this study, we find that pVHL binding protein 1 (VBP1) is a negative regulator of HIF-1α but not HIF-2α using zebrafish as an invivo model and invitro cell culture models. Deletion of vbp1 in zebrafish caused Hif-1α accumulation and upregulation of Hif target genes. Moreover, vbp1 was involved in the induction of hematopoietic stem cells (HSCs) under hypoxic conditions. However, VBP1 interacted with and promoted the degradation of HIF-1α in a pVHL-independent manner. Mechanistically, we identify the ubiquitin ligase CHIP and HSP70 as new VBP1 binding partners and demonstrate that VBP1 negatively regulated CHIP and facilitated CHIP-mediated degradation of HIF-1α. In patients with clear cell renal cell carcinoma (ccRCC), lower VBP1 expression was associated with worse survival outcomes. In conclusion, our results link VBP1 with CHIP stability and provide insights into underlying molecular mechanisms of HIF-1α-driven pathological processes.

Molecular Characterization and Functional Analysis of Hypoxia-Responsive Factor Prolyl Hydroxylase Domain 2 in Mandarin Fish (Siniperca chuatsi).

With increased breeding density, the phenomenon of hypoxia gradually increases in aquaculture. Hypoxia is primarily mediated by the hypoxia-inducible factor 1 (HIF-1) signaling pathway. Prolyl hydroxylase domain proteins (PHD) are cellular oxygen-sensing molecules that regulate the stability of HIF-1α through hydroxylation. In this study, the characterization of the PHD2 from mandarin fish Siniperca chuatsi (scPHD2) and its roles in the HIF-1 signaling pathway were investigated. Bioinformation analysis showed that scPHD2 had the conserved prolyl 4-hydroxylase alpha subunit homolog domains at its C-terminal and was more closely related to other Perciformes PHD2 than other PHD2. Tissue-distribution results revealed that scphd2 gene was expressed in all tissues tested and more highly expressed in blood and liver than in other tested tissues. Dual-luciferase reporter gene and RT-qPCR assays showed that scPHD2 overexpression could significantly inhibit the HIF-1 signaling pathway. Co-immunoprecipitation analysis showed that scPHD2 could interact with scHIF-1α. Protein degradation experiment results suggested that scPHD2 could promote scHIF-1α degradation through the proteasome degradation pathway. This study advances our understanding of how the HIF-1 signaling pathway is regulated by scPHD2 and will help in understanding the molecular mechanisms underlying hypoxia adaptation in teleost fish.

High-resolution temporal transcriptomic profiling of the distal convoluted tubule identifies an early adaptive response to furosemide

The distal convoluted tubule (DCT) undergoes hypertrophy and hyperplasia to increase salt absorption in response to physiologic and pathological stresses, and has been implicated in the development of loop-diuretic resistance. However, the molecular mechanisms underlying DCT remodeling are unknown. We investigated progressive changes in the transcriptome of the early DCT (DCT1) in a time series (12, 24, 48, and 96 hours) after the administration of furosemide to identify initiating gene regulatory pathways. For high-resolution coverage, RNAseq was performed on isolated DCT1 segments, identified using a DCT1-specific Cre-driven fluorescent protein, tdTomato. An average of 17 million sequences were read per sample, providing genome-wide coverage of the DCT transcriptome (15499 genes). Sequence reads aligned on the mouse transcripts were quantified using Salmon, and differential gene expression analysis was performed using edgeR. All samples were enriched with known DCT-specific genes and lacked other nephron segment specific markers, indicating uniform purification of DCT tubules. Pathway and pattern clustering analysis of the time-resolved DCT transcriptome profiles revealed the early-induced genes were highly enriched in gene sets associated with cell cycle progression and cell proliferation. Meta-analysis of transcription factor binding enrichment at promoters of the early-induced genes revealed enrichment of genomic binding sites of Hypoxia-inducible factor 1 (HIF-1) signaling components (HIF1A, STAT3, RELA) across the early-induced gene promoters. Immunoblot analysis in kidney cortical tissues confirmed rapid activation of the HIF-1 signaling components following furosemide treatment. In summary, a core transcriptional regulatory axis in the DCT is activated rapidly after loop-diuretic treatment to drive a program of cell proliferation in the DCT. The results identify HIF1 signaling as a proximal pathway in the initiation of proliferative DCT remodeling. NIDDK, LeDucq Foundation This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Bioinformatics analysis of potential key ferroptosis-related genes involved in tubulointerstitial injury in patients with diabetic nephropathy

Diabetic nephropathy (DN) is the primary complication of diabetes mellitus. Ferroptosis is a form of cell death that plays an important role in DN tubulointerstitial injury, but the specific molecular mechanism remains unclear. Here, we downloaded the DN tubulointerstitial datasets GSE104954 and GSE30529 from the Gene Expression Omnibus database. We examined the differentially expressed genes (DEGs) between DN patients and healthy controls, and 36 ferroptosis-related DEGs were selected. Pathway-enrichment analyses showed that many of these genes are involved in metabolic pathways, phosphoinositide 3-kinase/Akt signaling, and hypoxia-inducible factor-1 signaling. Ten of the 36 ferroptosis-related DEGs (CD44, PTEN, CDKN1A, DPP4, DUSP1, CYBB, DDIT3, ALOX5, VEGFA, and NCF2) were identified as key genes. Expression patterns for six of these (CD44, PTEN, DDIT3, ALOX5, VEGFA, and NCF2) were validated in the GSE30529 dataset. Nephroseq data indicated that the mRNA expression levels of CD44, PTEN, ALOX5, and NCF2 were negatively correlated with the glomerular filtration rate (GFR), while VEGFA and DDIT3 mRNA expression levels were positively correlated with GFR. Immune infiltration analysis demonstrated altered immunity in DN patients. Real-time quantitative PCR (qPCR) analysis showed that ALOX5, PTEN, and NCF2 mRNA levels were significantly upregulated in high-glucose-treated human proximal tubular (HK-2) cells, while DDIT3 and VEGFA mRNA levels were significantly downregulated. Immunohistochemistry analysis of human renal biopsies showed positive staining for ALOX5 and NCF2 protein in DN samples but not the controls. These key genes may be involved in the molecular mechanisms underlying ferroptosis in patients with DN, potentially through specific metabolic pathways and immune/inflammatory mechanisms.

Genome-Wide Analysis of Hypoxia-Inducible Factor Binding Reveals Targets Implicated in Impaired Human Placental Syncytiotrophoblast Formation under Low Oxygen

Preeclampsia (PE) is a common and serious complication of pregnancy with no cure except premature delivery. The root cause of PE is improper development of the placenta-the temporary organ supporting fetal growth and development. Continuous formation of the multinucleated syncytiotrophoblast (STB) layer via differentiation and fusion of cytotrophoblasts (CTBs) is vital for healthy placentation and is impaired in preeclamptic pregnancies. In PE, there is reduced/intermittent placental perfusion, likely resulting in a persistently low O2 environment. Low O2 inhibits differentiation and fusion of CTBs into STB and may thus contribute to PE pathogenesis; however, the underlying mechanisms are unknown. Because low O2 activates a transcription factor complex in cells known as the hypoxia-inducible factor (HIF), the objective of this study was to investigate whether HIF signaling inhibits STB formation by regulating genes required for this process. Culture of primary CTBs, the CTB-like cell line BeWo, and human trophoblast stem cells under low O2 reduced cell fusion and differentiation into STB. Knockdown of aryl hydrocarbon receptor nuclear translocator (a key component of the HIF complex) in BeWo cells restored syncytialization and expression of STB-associated genes under different O2 levels. Chromatin immunoprecipitation sequencing facilitated the identification of global aryl hydrocarbon receptor nuclear translocator/HIF binding sites, including several near genes implicated in STB development, such as ERVH48-1 and BHLHE40, providing new insights into mechanisms underlying pregnancy diseases linked to poor placental O2 supply.

Ferroptosis Regulated by Hypoxia in Cells.

Ferroptosis is an oxidative damage-related, iron-dependent regulated cell death with intracellular lipid peroxide accumulation, which is associated with many physiological and pathological processes. It exhibits unique features that are morphologically, biochemically, and immunologically distinct from other regulated cell death forms. Ferroptosis is regulated by iron metabolism, lipid metabolism, anti-oxidant defense systems, as well as various signal pathways. Hypoxia, which is found in a group of physiological and pathological conditions, can affect multiple cellular functions by activation of the hypoxia-inducible factor (HIF) signaling and other mechanisms. Emerging evidence demonstrated that hypoxia regulates ferroptosis in certain cell types and conditions. In this review, we summarize the basic mechanisms and regulations of ferroptosis and hypoxia, as well as the regulation of ferroptosis by hypoxia in physiological and pathological conditions, which may contribute to the numerous diseases therapies.

MTORC1 Deficiency Prevents the Development of MC903-Induced Atopic Dermatitis through the Downregulation of Type 2 Inflammation.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by eczema and itching. Recently, mTORC, a central regulator of cellular metabolism, has been reported to play a critical role in immune responses, and manipulation of mTORC pathways has emerged as an effective immunomodulatory drug. In this study, we assessed whether mTORC signaling could contribute to the development of AD in mice. AD-like skin inflammation was induced by a 7-day treatment of MC903 (calcipotriol), and ribosomal protein S6 was highly phosphorylated in inflamed tissues. MC903-induced skin inflammation was ameliorated significantly in Raptor-deficient mice and exacerbated in Pten-deficient mice. Eosinophil recruitment and IL-4 production were also decreased in Raptor deficient mice. In contrast to the pro-inflammatory roles of mTORC1 in immune cells, we observed an anti-inflammatory effect on keratinocytes. TSLP was upregulated in Raptor deficient mice or by rapamycin treatment, which was mediated by hypoxia-inducible factor (HIF) signaling. Taken together, these results from our study indicate the dual roles of mTORC1 in the development of AD, and further studies on the role of HIF in AD are warranted.

The role of hypoxia-inducible factor 1 alpha (HIF-1α) modulation in heavy metal toxicity.

Hypoxia-inducible factor 1 (HIF-1) is an oxygen-sensing transcriptional regulator orchestrating a complex of adaptive cellular responses to hypoxia. Several studies have demonstrated that toxic metal exposure may also modulate HIF-1α signal transduction pathway, although the existing data are scarce. Therefore, the present review aims to summarize the existing data on the effects of toxic metals on HIF-1 signaling and the potential underlying mechanisms with a special focus on prooxidant effect of the metals. The particular effect of metals was shown to be dependent on cell type, varying from down- to up-regulation of HIF-1 pathway. Inhibition of HIF-1 signaling may contribute to impaired hypoxic tolerance and adaptation, thus promoting hypoxic damage in the cells. In contrast, its metal-induced activation may result in increased tolerance to hypoxia through increased angiogenesis, thus promoting tumor growth and contributing to carcinogenic effect of heavy metals. Up-regulation of HIF-1 signaling is mainly observed upon Cr, As, and Ni exposure, whereas Cd and Hg may both stimulate and inhibit HIF-1 pathway. The mechanisms underlying the influence of toxic metal exposure on HIF-1 signaling involve modulation of prolyl hydroxylases (PHD2) activity, as well as interference with other tightly related pathways including Nrf2, PI3K/Akt, NF-κB, and MAPK signaling. These effects are at least partially mediated by metal-induced ROS generation. Hypothetically, maintenance of adequate HIF-1 signaling upon toxic metal exposure through direct (PHD2 modulation) or indirect (antioxidant) mechanisms may provide an additional strategy for prevention of adverse effects of metal toxicity.

"Drying effect" of fructus aurantii components and the mechanism of action based on network pharmacology and in vitro pharmacodynamic validation.

Background: Fructus aurantii (FA) is the dried, unripe fruit of the plant Citrus aurantium L. and its cultivated varieties. We investigated the drying effect of FA components and how this drying affect is achieved. Methods: We employed systems pharmacology to predict the components and targets of FA that produce its drying effect. These predictions were verified by computer simulation and animal experiments. In the latter, we measured the bodyweight, water consumption, urine output, fecal water content, rate of salivary secretion, and cross-sectional area of the long axis of the submandibular gland of mice. Immunohistochemistry was used to measure expression of aquaporin (AQP)5 in the submandibular gland, AQP2 in the kidney, and AQP3 in the colon. ELISA kits were used to measure the horizontal variation of cyclic adenosine monsophosphate (cAMP), cyclic guanosine monophosphate (cGMP) and interferon-γ. Results: Sixty-seven potentially active components of FA were screened out. FA could produce a drying effect after regulating 214 targets through 66 active components. A total of 870 gene ontology (GO) terms and 153 signaling pathways were identified. The hypoxia inducible factor-1 signaling pathway, phosphoinositide 3-kinase-protein kinase B (PI3K-AKT) signaling pathway, calcium signaling pathway, and Ras signaling pathway may have important roles in the drying effect of FA. Four components of FA were identified: sinensetin, tangeretin, 5-demethylnobiletin and chrysin. These four components could increase the serum level of interferon-γ and ratio of cyclic adenosine monophosphate:cyclic guanosine monophosphate in mice, and affect their water consumption, urine output, fecal water content and rate of salivary secretion. Conclusion: Four components of FA (tangeretin, sinensetin, chrysin, 5-Demethylmobiletin) were closely related to the Janus kinase-signal transducer and activator of transcription-3 (JAK-STAT3), PI3K-AKT, and the other signaling pathways. They can regulate the protein expression of JAK2, STAT3, PI3K, lymphocyte cell-specific protein-tyrosine kinase, vascular endothelial growth factor A, and protein kinase B1, affect water metabolism in the body and, finally, result in a drying effect.

Proteome architecture of human-induced pluripotent stem cell-derived three-dimensional organoids as a tool for early diagnosis of neuronal disorders.

Induced pluripotent stem cells (iPSCs) derived three-dimensional (3D) model for rare neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) is emerging as a novel alternative to human diseased tissue to explore the disease etiology and potential drug discovery. In the interest of the same, we have generated a TDP-43-mutated human iPSCs (hiPSCs) derived 3D organoid model of ALS disease. The high-resolution mass spectrometry (MS)-based proteomic approach is used to explore the differential mechanism under disease conditions and the suitability of a 3D model to study the disease. The hiPSCs cell line was procured from a commercial source, grown, and characterized following standard protocols. The mutation in hiPSCs was accomplished using CRISPR/Cas-9 technology and predesigned gRNA. The two groups of organoids were produced by normal and mutated hiPSCs and subjected to the whole proteomic profiling by high-resolution MS in two biological replicates with three technical replicas of each. The proteomic analysis of normal and mutated organoids revealed the proteins associated with pathways of neurodegenerative disorders, proteasomes, autophagy, and hypoxia-inducible factor-1 signaling. Differential proteomic analysis revealed that the mutation in TDP-43 gene caused proteomic deregulation, which impaired protein quality mechanisms. Furthermore, this impairment may contribute to the generation of stress conditions that may ultimately lead to the development of ALS pathology. The developed 3D model represents the majority of candidate proteins and associated biological mechanisms altered in ALS disease. The study also offers novel protein targets that may uncloud the precise disease pathological mechanism and be considered for future diagnostic and therapeutic purposes for various neurodegenerative disorders.

Hypoxia-Inducible Factor-2α Signaling in the Skeletal System.

Hypoxia-inducible factors (HIFs) are oxygen-dependent heterodimeric transcription factors that mediate molecular responses to reductions in cellular oxygen (hypoxia). HIF signaling involves stable HIF-β subunits and labile, oxygen-sensitive HIF-α subunits. Under hypoxic conditions, the HIF-α subunit is stabilized, complexes with nucleus-confined HIF-β subunit, and transcriptionally regulates hypoxia-adaptive genes. Transcriptional responses to hypoxia include altered energy metabolism, angiogenesis, erythropoiesis, and cell fate. Three isoforms of HIF-α-HIF-1α, HIF-2α, and HIF-3α-are found in diverse cell types. HIF-1α and HIF-2α serve as transcriptional activators, whereas HIF-3α restricts HIF-1α and HIF-2α. The structure and isoform-specific functions of HIF-1α in mediating molecular responses to hypoxia are well established across a wide range of cell and tissue types. The contributions of HIF-2α to hypoxic adaptation are often unconsidered if not outrightly attributed to HIF-1α. This review establishes what is currently known about the diverse roles of HIF-2α in mediating the hypoxic response in skeletal tissues, with specific focus on development and maintenance of skeletal fitness. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Air–liquid interface cultures trigger a metabolic shift in intestinal epithelial cells (IPEC-1)

An improved oxygen availability in air–liquid interface (ALI) cultures of enterocytes of the small intestine seems to be primarily responsible for morphological, metabolic, and functional changes. Intestinal porcine epithelial cells 1 (IPEC-1) are less investigated and are rarely used as model for intestinal barrier but showed a profound change of cell shape during ALI cultivation. We aim to answer the following question: Are the observed morphological effects accompanied by changes in metabolic function? A microarray analysis of submerged culture (SMC) and ALI cultures identified 830 significantly regulated genes. Subsequent functional clustering revealed alterations in 31 pathways, with the highest number of regulated genes in metabolic pathways, carbon metabolism, glycolysis, and hypoxia-inducible factor (HIF) signaling. Furthermore, HIF-1α as a mediator of a metabolic switch between glycolysis and oxidative phosphorylation showed a trend of increased mRNA levels in ALI in contrast to a reduced nuclear HIF-1α content in the nucleus. Candidate genes of oxidative phosphorylation such as a mitochondrial marker exhibited enhanced mRNA levels, which was confirmed by western blot analysis. Cytochrome C oxidase (COX) subunit 5B protein was decreased in ALI, although mRNA level was increased. The oxidation of ferrocytochrome C to ferricytochrome C was used for detection of cytochrome C oxidase activity of isolated mitochondria and resulted in a trend of higher activity in ALI. Furthermore, quantification of glucose and lactate concentrations in cell culture medium revealed significantly reduced glucose levels and decreased lactate production in ALI. To evaluate energy metabolism, we measured cellular adenosine triphosphate (ATP) aggregation in homogenized cell suspensions showing similar levels. However, application of the uncoupling agent FCCP reduced ATP levels in ALI but not in SMC. In contrast, blocking with 2-desoxy-d-glucose (2DG) significantly reduced ATP content in ALI and SMC. These results indicate a metabolic shift in IPEC-1 cultured under ALI conditions enhancing oxidative phosphorylation and suppressing glycolysis.

Roxadustat, a HIF-PHD inhibitor with exploitable potential on diabetes-related complications.

Diabetes mellitus (DM) is a group of metabolic diseases caused by absolute or relative deficiency of insulin secretion and characterized by chronic hyperglycemia. Its complications affect almost every tissue of the body, usually leading to blindness, renal failure, amputation, etc. and in the final stage, it mostly develops into cardiac failure, which is the main reason why diabetes mellitus manifests itself as a high clinical lethality. The pathogenesis of diabetes mellitus and its complications involves various pathological processes including excessive production of mitochondrial reactive oxygen species (ROS) and metabolic imbalance. Hypoxia-inducible Factor (HIF) signaling pathway plays an important role in both of the above processes. Roxadustat is an activator of Hypoxia-inducible Factor-1α, which increases the transcriptional activity of Hypoxia-inducible Factor-1α by inhibiting hypoxia-inducible factor prolyl hydroxylase (HIF-PHD). Roxadustat showed regulatory effects on maintaining metabolic stability in the hypoxic state of the body by activating many downstream signaling pathways such as vascular endothelial growth factor (VEGF), glucose transporter protein-1 (GLUT1), lactate dehydrogenase (LDHA), etc. This review summarizes the current research findings of roxadustat on the diseases of cardiomyopathy, nephropathy, retinal damage and impaired wound healing, which also occur at different stages of diabetes and greatly contribute to the damage caused by diabetes to the organism. We attempts to uncover a more comprehensive picture of the therapeutic effects of roxadustat, and inform its expanding research about diabetic complications treatment.

Proteomic profiling of human corneal stroma from long-term contact lens wearers reveals activation of inflammatory responses

PurposeTo investigate the association between proteomic changes and potential pathogenesis in the human cornea with respect to the duration of wearing soft contact lenses (SCLs). MethodsA total of 96 corneal stroma samples, obtained via small incision lenticule extraction (SMILE), were equally grouped according to the duration of wearing SCL: 0Y, did not wear SCL; 5Y, wore SCL for<5 years; 5–10Y, wore SCL for 5–10 years; O10Y, wore SCL for>10 years. Liquid chromatography–tandem mass spectrometry was used to identify and quantify protein profiles in the corneal stroma. Expression levels of CO1A1, CO4A1, NFKB1, and IL6RB were determined using western blot and immunohistochemistry analysis. ResultsThis study quantified a total of 5,668 proteins across samples and identified 2,379 differentially expressed proteins (DEPs) with significantly increased abundance in the three SCL-wearing groups compared with that in the non-SCL-wearing group. Compared with those in the 0Y group, the molecular functions of DEPs in the 5Y, 5–10Y, and O10Y groups were mainly related to translation regulator activity, antigen binding, peptidase inhibitor activity, participation in extracellular matrix (ECM) production, complement activation, and inflammatory responses. Pathway enrichment analysis of DEPs showed that the sphingolipid, phosphatidylinositol 3-kinase-protein kinase B, and hypoxia-inducible factor-1 signaling pathways were activated in the human corneal stroma after long-term SCL use. ConclusionsInflammation-related proteomic components in human corneal stroma increased after long-term use of SCL and may act as an essential factor in the molecular pathogenesis of corneal stroma damage.

Jian Pi Sheng Sui Gao (JPSSG) alleviation of skeletal myoblast cell apoptosis, oxidative stress, and mitochondrial dysfunction to improve cancer-related fatigue in an AMPK-SIRT1- and HIF-1-dependent manner.

Jian Pi Sheng Sui Gao (JPSSG), a Chinese traditional herbal paste, possesses certain efficacy in patients with cancer-related fatigue (CRF); however, its related mechanism remains unclear. Hence, network pharmacology analysis, followed by in vivo and in vitro experiments were conducted in this study with the aim to evaluate the effect of JPSSG on CRF and clarify its potential mechanism. Network pharmacology analysis was performed. Subsequently, 12 mice were injected with CT26 cells to establish CRF mouse models and randomly divided into a model group (n=6) and JPSSG group (n=6); meanwhile, another 6 normal mice served as a control group. Then, 3.0 g/kg JPSSG was given to mice in JPSSG group for 15 days, while mice in the n control and model groups received phosphate-buffered saline (PBS) of the same volume for 15 days. For the in vitro experiment, CT26 conditioned medium (CM) was established; meanwhile, the mitochondrial damage model was constructed through C2C12 myotubes stimulated with H2O2. C2C12 myotubes were divided into 5 groups: control group (without treatment), CM group, CM + JPSSG group, H2O2 group, and H2O2 + JGSSP group. Network pharmacology analysis identified 87 bioactive compounds and 132 JPSSG-CRF interaction targets. Moreover, according to the Kyoto Encyclopedia of Genes and Genomes enrichment analysis and the subsequent in vivo and in vitro experiments, JPSSG activated adenosine 5'-monophosphate-activated protein kinase-silent-information-regulator factor 2-related-enzyme 1 (AMPK-SIRT1) and hypoxia-inducible factor-1 (HIF-1) signaling pathways during CRF. Moreover, the in vivo experiment showed that JPSSG attenuated CRF in mice, reflected by increased distance traveled, mobile time in open field test, and swimming time in exhaustive swimming test, and decreased absolute rest time and tail suspension test in the JPSSG group (vs. model group). Furthermore, JPSSG upregulated gastrocnemius weight, adenosine triphosphate (ATP), superoxide dismutase (SOD), and the cross-sectional area of the gastrocnemius. With regard to in vitro study, JPSSG elevated cell viability, B-cell lymphoma-2, ATP, SOD, and mitochondrial membrane potential, while it decreased apoptosis rate, cleaved-caspase3, malondialdehyde, and reactive oxygen species in C2C12 myotubes. JPSSG ameliorates CRF via alleviating skeletal myoblast cell apoptosis, oxidative stress, and mitochondrial dysfunction in an AMPK-SIRT1- and HIF-1-dependent manner.

Material basis and mechanism of Curcuma longa tuberous roots with and without vinegar processing in treating primary dysmenorrhea

Liquid chromatography-mass spectrometry was employed to analyze the chemical components in Curcuma longa tuberous roots(HSYJ), C. longa tuberous roots processed with vinegar(CHSYJ), and rat serum after the administration. The active components of HSYJ and CHSYJ absorbed in serum were identified based on the secondary spectrum of database and literature. The targets of primary dysmenorrhea was screened out from database. The protein-protein interaction network analysis, gene ontology(GO) functional annotation, and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analysis were performed for the common targets shared by the drug active components in serum and primary dysmenorrhea, and the component-target-pathway network was constructed. AutoDock was used to conduct molecular docking between the core components and targets. A total of 44 chemical components were identified from HSYJ and CHSYJ, including 18 absorbed in serum. On the basis of network pharmacology, we identified 8 core components(including procurcumenol, isobutyl p-hydroxybenzoate, ferulic acid, and zedoarondiol) and 10 core targets \[including interleukin-6(IL-6), estrogen receptor 1(ESR1), and prostaglandin-endoperoxide synthase 2(PTGS2)\]. The core targets were mainly distributed in the heart, liver, uterus, and smooth muscle. The molecular docking results showed that the core components were well bound to the core targets, indicating that HSYJ and CHSYJ may exert therapeutic effect on primary dysmenorrhea via estrogen, ovarian steroidogenesis, tumor necrosis factor(TNF), hypoxia-inducible factor-1(HIF-1), IL-17 and other signaling pathways. This study clarifies the HSYJ and CHSYJ components absorbed in serum, as well as the corresponding mechanism, providing a reference for further elucidating the therapeutic material basis and clinical application of HSYJ and CHSYJ.