Expression Of Hypoxia-inducible Factor Research Articles

Hypoxia signaling in the equine small intestine: Expression and distribution of hypoxia inducible factors during experimental ischemia.

Hypoxia inducible factors (HIF) are widely researched in human medicine for their role in different disease processes. The aim of this study was to investigate the expression and distribution of HIF in experimental small intestinal ischemia in the horse. In 14 horses under general anesthesia, segmental jejunal ischemia with 90% reduction in blood flow was induced. The horses were randomly divided into two groups of seven horses, one subjected to ischemic postconditioning (IPoC) by delayed reperfusion, and a control group (group C) undergoing undelayed reperfusion. Intestinal samples were taken pre-ischemia, after ischemia and after reperfusion. Following immunohistochemical staining for HIF1α and -2α, the immunoreactivity pattern in the small intestine was evaluated by light microscopy, and the mucosal enterocyte and muscularis staining were semi-quantitatively scored. Additionally, mucosal HIF1α protein levels were determined by an Enzyme Linked Immunosorbent Assay (ELISA), and mRNA levels of HIF1α and its target genes by a two-step real-time Reverse Transcriptase Polymerase Chain Reaction. Statistical comparison was performed between the groups and time points using parametric and non-parametric tests (p < 0.05). All cell types exhibited cytoplasmic and nuclear immunoreactivity for HIF1α. After reperfusion, the cytoplasmic staining of the crypt and villus enterocytes as well as the villus nuclear staining significantly increased, whereas the perinuclear granules in the crypts decreased. The protein levels showed a significant decrease in group C at reperfusion, with lower HIF1α levels in group C compared to group IPoC during ischemia and reperfusion. No other group differences could be detected. In the HIF2α stained slides, mild to moderate cytoplasmic staining yet no nuclear immunoreactivity of the enterocytes was observed, and no significant changes over time were noted. the changes in HIF1α immunoreactivity pattern and expression over time suggest that this transcription factor plays a role in the intestinal response to ischemia in horses. However, the current study could not identify an effect of IPoC on HIF distribution or expression.

Placental nanoparticle gene therapy normalizes gene expression changes in the fetal liver associated with fetal growth restriction in a fetal sex-specific manner.

Fetal growth restriction (FGR) is associated with increased risk of developing non-communicable diseases. We have a placenta-specific nanoparticle gene therapy protocol that increases placental expression of human insulin-like growth factor 1 (hIGF1), for the treatment of FGR in utero. We aimed to characterize the effects of FGR on hepatic gluconeogenesis pathways during early stages of FGR establishment, and determine whether placental nanoparticle-mediated hIGF1 therapy treatmentcould resolve differences in the FGR fetus. Female Hartley guinea pigs (dams) were fed either a Control or Maternal Nutrient Restriction (MNR) diet using established protocols. At GD30-33, dams underwent ultrasound guided, transcutaneous, intraplacental injection of hIGF1 nanoparticle or PBS (sham) and were sacrificed 5 days post-injection. Fetal liver tissue was fixed and snap frozen for morphology and gene expression analysis. In female and male fetuses, liver weight as a percentage of body weight was reduced by MNR, and not changed with hIGF1 nanoparticle treatment. In female fetal livers, expression of hypoxia inducible factor 1 (Hif1α) and tumor necrosis factor (Tnfα) were increased in MNR compared to Control, but reduced in MNR + hIGF1 compared to MNR. In male fetal liver, MNR increased expression of Igf1 and decreased expression of Igf2 compared to Control. Igf1 and Igf2 expression was restored to Control levels in the MNR + hIGF1 group. This data provides further insight into the sex-specific mechanistic adaptations seen in FGR fetuses and demonstrates that disruption to fetal developmental mechanisms may be returned to normal by treatment of the placenta.

Effect of miR‑29a‑3p in exosomes on glioma cells by regulating the PI3K/AKT/HIF‑1α pathway.

Exosomes secreted by glioma cells can carry a number of bioactive molecules. As the most abundant noncoding RNA in exosomes, microRNAs (miRNAs) are involved in signaling between tumor cells in a number of ways. In addition, hypoxia is an important feature of the microenvironment of most tumors. The present study investigated the effect of miR‑29a‑3p in glioma exosomes on the proliferation and apoptosis levels of U251 glioma cells under hypoxia. Qualitative PCR results showed that the expression level of miR‑29a‑3p in plasma exosomes of glioma patients was lower than that of normal subjects. By conducting hypoxia experiments invitro on U251 glioma cells, it was found that the expression level of miR‑29a‑3p decreased following hypoxia, while overexpression of miR‑29a‑3p significantly decreased the proliferation of U251 glioma cells and promoted apoptosis by inhibiting the expression of the antiapoptotic marker Bcl‑2 and increasing the expression of the proapoptotic marker Bax The potential targets of miR‑29a‑3p were predicted by online tools and validated by a dual‑luciferase gene reporter assay. miR‑29a‑3p was found to target and regulate PI3K, which in turn inhibited the activity of the PI3K‑AKT pathway, thereby reducing the expression of hypoxia inducible factor (HIF)‑1α protein. Furthermore, the effects of miR‑29a‑3p on proliferation and apoptosis in glioma cells in those processes could be reversed by the PI3K‑AKT agonist Recilisib. In addition, the inhibitory effect of miR‑29a‑3p on the PI3K/AKT/HIF‑1α regulatory axis could cause a decrease in the expression levels of pyruvate dehydrogenase kinase‑1 and pyruvate dehydrogenase kinase‑2 and eventually lead to a reduction in glycolysis in U251 glioma cells. Similarly, Recilisib slowed the inhibitory effect of miR‑29a‑3p on glycolysis and glycolysis‑related molecules. The results of this study tentatively confirm that miR‑29a‑3p carried by exosomes can be used as a novel diagnostic marker and a potential inhibitory molecule for glioma cells, providing a new theoretical and experimental basis for the precise clinical treatment of glioma.

Hypoxia Pathway in Osteoporosis: Laboratory Data for Clinical Prospects.

The hypoxia pathway not only regulates the organism to adapt to the special environment, such as short-term hypoxia in the plateau under normal physiological conditions, but also plays an important role in the occurrence and development of various diseases such as cancer, cardiovascular diseases, osteoporosis. Bone, as a special organ of the body, is in a relatively low oxygen environment, in which the expression of hypoxia-inducible factor (HIF)-related molecules maintains the necessary conditions for bone development. Osteoporosis disease with iron overload endangers individuals, families and society, and bone homeostasis disorder is linked to some extent with hypoxia pathway abnormality, so it is urgent to clarify the hypoxia pathway in osteoporosis to guide clinical medication efficiently. Based on this background, using the keywords "hypoxia/HIF, osteoporosis, osteoblasts, osteoclasts, osteocytes, iron/iron metabolism", a matching search was carried out through the Pubmed and Web Of Science databases, then the papers related to this review were screened, summarized and sorted. This review summarizes the relationship and regulation between the hypoxia pathway and osteoporosis (also including osteoblasts, osteoclasts, osteocytes) by arranging the references on the latest research progress, introduces briefly the application of hyperbaric oxygen therapy in osteoporosis symptoms (mechanical stimulation induces skeletal response to hypoxic signal activation), hypoxic-related drugs used in iron accumulation/osteoporosis model study, and also puts forward the prospects of future research.

Diabetes-Induced Autophagy Dysregulation Engenders Testicular Impairment via Oxidative Stress.

Testes produce sperms, and gamete generation relies on a proper niche environment. The disruption of hierarchical regulatory homeostasis in Leydig or Sertoli cells may evoke a sterile phenotype in humans. In this study, we recapitulated type 2 diabetes mellitus by using a high-fat diet- (HFD-) fed mouse model to identify the phenotype and potential mechanism of diabetes-induced testicular impairment. At the end of the study, blood glucose levels, testosterone structure, testicular antioxidant capacity, and testosterone level and the expression of hypoxia-inducible factor- (HIF-) 1α, apoptosis-related protein cleaved-caspase3, and autophagy-related proteins such as LC3I/II, p62, and Beclin1 were evaluated. We found that long-term HFD treatment causes the development of diabetes mellitus, implicating increased serum glucose level, cell apoptosis, and testicular atrophy (P < 0.05 vs. Ctrl). Mechanistically, the results showed enhanced expression of HIF-1α in both Sertoli and Leydig cells (P < 0.05 vs. Ctrl). Advanced glycation end products (AGEs) were demonstrated to be a potential factor leading to HIF-1α upregulation in both cell types. In Sertoli cells, high glucose treatment had minor effects on Sertoli cell autophagy. However, AGE treatment stagnated the autophagy flux and escalated cell apoptosis (P < 0.05 vs. Ctrl+Ctrl). In Leydig cells, high glucose treatment was adequate to encumber autophagy induction and enhance oxidative stress. Similarly, AGE treatment facilitated HIF-1α expression and hampered testosterone production (P < 0.05 vs. Ctrl+Ctrl). Overall, these findings highlight the dual effects of diabetes on autophagy regulation in Sertoli and Leydig cells while imposing oxidative stress in both cell types. Furthermore, the upregulation of HIF-1α, which could be triggered by AGE treatment, may negatively affect both cell types. Together, these findings will help us further understand the molecular mechanism of diabetes-induced autophagy dysregulation and testicular impairment, enriching the content of male reproductive biology in diabetic patients.

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors and Iron Metabolism.

The production of erythropoietin (EPO), the main regulator of erythroid differentiation, is regulated by hypoxia-inducible factor (HIF). HIF2α seems to be the principal regulator of EPO transcription, but HIF1α and 3α also may have additional influences on erythroid maturation. HIF is also involved in the regulation of iron, an essential component in erythropoiesis. Iron is essential for the organism but is also highly toxic, so its absorption and retention are strictly controlled. HIF also induces the synthesis of proteins involved in iron regulation, thereby ensuring the availability of iron necessary for hematopoiesis. Iron is a major component of hemoglobin and is also involved in erythrocyte differentiation and proliferation and in the regulation of HIF. Renal anemia is a condition in which there is a lack of stimulation of EPO synthesis due to decreased HIF expression. HIF prolyl hydroxylase inhibitors (HIF-PHIs) stabilize HIF and thereby allow it to be potent under normoxic conditions. Therefore, unlike erythropoiesis-stimulating agents, HIF-PHI may enhance iron absorption from the intestinal tract and iron supply from reticuloendothelial macrophages and hepatocytes into the plasma, thus facilitating the availability of iron for hematopoiesis. The only HIF-PHI currently on the market worldwide is roxadustat, but in Japan, five products are available. Clinical studies to date in Japan have also shown that HIF-PHIs not only promote hematopoiesis, but also decrease hepcidin, the main regulator of iron metabolism, and increase the total iron-binding capacity (TIBC), which indicates the iron transport capacity. However, concerns about the systemic effects of HIF-PHIs have not been completely dispelled, warranting further careful monitoring.

Chronic Treatment with Aβ42 with a Toxic Conformer and LPS Induces Inflammatory Responses in BV-2 Microglia with Dysregulation of Hypoxia-Inducible Factor Expression.

Amyloid β (Aβ) plays a key role in the pathology of Alzheimer's disease (AD) and is toxic owing to its ability to aggregate into oligomers and fibrils. Aβ has high aggregative ability and potent toxicity due to the "toxic turn" at positions 22 and 23. Furthermore, APP knock-in mice producing E22P-Aβ with the toxic turn exhibited AD-related phenotypes such as cognitive impairment, Aβ plaque accumulation, and tau hyperphosphorylation. In these mice, it is suggested that the activation of neuroinflammation and dysregulation of hypoxia-inducible factor (HIF) expression in the hippocampus contribute to the pathogenesis of AD-related phenotype. However, it remains unclear which cells are responsible for the dysregulation of HIF expression and the neuroinflammation which was induced by E22P-Aβ with the toxic turn. Here, we investigated the effects of chronic treatment with E22P-Aβ42 and lipopolysaccharides (LPS) on the inflammatory response in BV-2 microglia. Chronic treatment with E22P-Aβ42 and LPS increased nitric oxide production and the expression of interleukin-6 (IL-6), whereas it reduced the expression of HIF-1α and HIF-3α in BV-2 microglia. The reduction of HIF-1α caused by E22P-Aβ42 and LPS was milder than that caused by LPS. Furthermore, chronic treatment with E22P-Aβ42 and LPS increased the nuclear translocation of nuclear factor-kappaB (NF-κB). E22P-Aβ42 could enhance the inflammatory response of microglia with abnormal HIF signaling and contribute to the progression of AD pathology.

Hypoxia inducible factor (HIF - 1 alpha) expression as an indicator of clinico-pathological characteristics & loco-regional control in squamous cell carcinoma of the Tongue.

Hypoxia inducible factor (HIF - 1 alpha) expression as an indicator of clinico-pathological characteristics & loco-regional control in squamous cell carcinoma of the Tongue.

Functionalized exosome-loaded ginsenoside Rg1 for the treatment of ischemic stroke

The aim of this study was to investigate the therapeutic effects and potential mechanism of c(RGDyK) peptide modified mesenchymal stem cell exosomes loaded with ginsenoside Rg1 (G-Rg1) on ischemic stroke. Thread-tying method was used to establish SD rats transient middle cerebral occlusion model (tMCAO). The model rats were randomly divided into tMCAO group, Exo group, free G-Rg1 group, Exo-Rg1 group and cRGD-Exo-Rg1 group, and sham group was used as control. The infarct volume was measured by 2, 3, 5-triphenyltetrachloride (TTC) staining, the changes of neuron and endothelium were observed by immunofluorescence, and the expression of related proteins was detected by Western blotting. The results showed that cRGD-Exo-Rg1 up-regulated the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIF-1α) by activating PI3K/AKT pathway, thus promoting angiogenesis and neurogenesis, effectively reducing the volume of cerebral infarction and improving neural function. In addition, the delivery of cRGD-Exo-Rg1 to ischemic brain tissue up-regulated the expression of occludin and claudin-5, and reduced the injury of blood-brain barrier. Taken together, cRGD-Exo-Rg1 was effective in the treatment of ischemic stroke by promoting angiogenesis and neurogenesis, which provided experimental evidence for the potential clinical benefits of other neuroprotective therapies.

HYPERBARIC OXYGEN THERAPY AS AN ADJUVANT TREATMENT IN HYDROCHLORIC ACID POISONING: A LITERATURE REVIEW

Highlights1. In Indonesia, 18.8% of all suicides were the result of chemical poisoning, such as using hydrochloric acid (HCl).2. Hyperbaric Oxygen Therapy (HBOT) can be used as an emergency therapy for acute pathology or as a supplementary treatment for chronic illness. AbstractBackground: Suicide is the second most common cause of death and is a major public health problem in many countries globally. Chemical poisoning, such as hydrochloric acid (HCl), accounted for 18.8% of the total suicide cases in Indonesia. Through ingestion, this acid chemical contributes as the most common cause of swallowing injuries that can adversely affect the gastrointestinal mucosal through various pathological processes, primarily through an excessive inflammatory process. On the other hand, hyperbaric oxygen therapy (HBOT) has been widely used as a non-pharmacological therapy in many diseases, although its mechanism for reducing inflammation in HCl poisoning has remained unclear. Objective: This study aimed to provide a better understanding on hyperbaric oxygen's biomolecular mechanism as a potential adjuvant therapy in HCl poisoning. Discussion: HCl poisoning causes an excessive inflammatory process, leading to tissue hypoxia indicated by increased expression of Hypoxia Inducible Factor 1 (HIF-1). Hyperbaric oxygen therapy decreases the expression of HIF-1 through activation of the HIF-1 hydroxylation pathway via prolyl hydroxylase (PDH) in the proline pathway and HIF inhibiting factor (FIH) in the asparagine pathway. Reactivating both pathways will decrease HIF-1 activity, eventually reducing the ongoing inflammatory process. In addition, HBOT also plays a role in wound healing by stimulating angiogenesis growth factors. Conclusion: Hyperbaric oxygen therapy has the potential to be used as adjuvant therapy in HCl poisoning due to its beneficial effects on reducing inflammatory mediators and wound healing.

High oxygen-modified packaging (HiOx-MAP) mediates HIF-1α regulation of tenderness changes during postmortem aging of yak meat

In the present study, we studied the effect of high oxygen-modified packaging (HiOx-MAP) on yak meat tenderness and the underlying mechanism. HiOx-MAP significantly increased the myofibril fragmentation index (MFI) of yak meat. In addition, western blotting showed that the expression of hypoxia-inducible factor (HIF-1α) and ryanodine receptors (RyR) in the HiOx-MAP group was reduced. HiOx-MAP increased the activity of sarcoplasmic reticulum calcium-ATPase (SERCA). The energy disperse spectroscopy (EDS) mapping showed gradually reduced calcium distribution in the treated endoplasmic reticulum. Furthermore, HiOx-MAP treatment increased the caspase-3 activity and the apoptosis rate. The activity of calmodulin protein (CaMKKβ) and AMP-activated protein kinase (AMPK) was down-regulated leading to apoptosis. These results indicated that HiOx-MAP promoted apoptosis during postmortem aging to improve the tenderization of meat.

ALKBH5 activates FAK signaling through m6A demethylation in ITGB1 mRNA and enhances tumor-associated lymphangiogenesis and lymph node metastasis in ovarian cancer.

Background: Lymph node (LN) metastasis is common in patients with epithelial ovarian cancer (EOC) and is associated with poor prognosis. Tumor-associated lymphangiogenesis is the first stage of LN metastasis. Research on lymphangiogenesis and lymph node metastases can help develop new anti-LN-targeted therapies. Aberrant N6-methyladenosine (m6A) modifications have been reported to be linked to LN metastasis in several cancers, however, their role in EOC lymphangiogenesis and LN metastasis remains unclear. Methods: m6A levels in EOC tissues with or without LN metastases were evaluated by dot blot analysis. Real-time polymerase chain reaction (PCR) and immunofluorescence were used to examine the expression of m6A-related enzymes. Additionally, in vitro and in vivo functional studies were performed to discover the importance of the AlkB homolog 5 (ALKBH5) gene in EOC lymphatic metastasis. To identify the downstream target genes regulated by ALKBH5, we performed RNA pulldown, RNA-binding protein immunoprecipitation-quantitative PCR, co-immunoprecipitation, m6A-modified RNA immunoprecipitation-quantitative PCR, and luciferase reporter assays. Results: m6A modification was reduced in ovarian cancers with LN metastases. ALKBH5 overexpression increased tumor-associated lymphangiogenesis and LN metastasis both in vitro and in vivo. ALKBH5 overexpression also reversed the m6A modification in ITGB1 mRNA and suppressed the YTHDF2 protein-mediated m6A-dependent ITGB1 mRNA degradation, which resulted in increased expression of ITGB1 and phosphorylation of the focal adhesion kinase (FAK) and Src proto-oncogene proteins, thereby increasing LN metastasis. Furthermore, hypoxia induced the expression of hypoxia inducible factor 1 subunit alpha, which increased ALKBH5 expression and enhanced LN metastasis in EOC. Conclusions: The ALKBH5/m6A-ITGB1/FAK signalling axis is important in ovarian cancer lymphangiogenesis and LN metastasis. Antibodies that block ITGB1 and FAK kinase-inhibitors are promising anti-metastatic agents.

Hypoxia inducible factors and hypoxia associated factor expression profiles and prognostic significance in renal cell carcinomas

Hypoxia Inducible Factor-1 alpha and Hypoxia Inducible Factor-2 alpha (HIF-1α and HIF-2α) are crucial in Renal Cell Carcinoma (RCC) formation. Hypoxia Associated Factor (HAF) prompts HIF-1α degradation regardless of oxygen levels, but no such link exists for HIF-2α. This study encompassed 239 cases, where tissue microarray (TMA) sections were exposed to HIF-1α, HIF-2α, and HAF antibodies. Staining intensity and tumor cell percentage determined scores for HIF-1α, HIF-2α, and HAF, with median histoscore establishing "high" or "low" cutoffs. Among the cases, 64.9% (155 cases) were negative for HIF-1α, 17.6% (42 cases) displayed low, and another 17.6% (42 cases) showed strong HIF-1α expression. HIF-1α expression correlated significantly with histological type and World Health Organization/International Society of Urological Pathology (WHO/ISUP) nuclear grade. Regarding HIF-2α, 15.5% (37 cases) were negative, 23.4% (56 cases) exhibited low, and 61.1% (146 cases) displayed high expression, with larger tumor size in the high HIF-2α group. Among 239 cases, 41.4% (99 cases) were negative for HAF, 36.8% (88 cases) showed low, and 21.8% (52 cases) displayed high HAF scores. HAF expression correlated with WHO/ISUP nuclear grade and metastasis presence. Notably, HIF-2α staining intensity directly correlated with increased HAF intensity (rho=0.146; p=0.024), while HIF-1α intensity decrease corresponded with heightened HAF intensity, showing a statistically significant negative correlation (rho=-0.180; p=0.005). In this rare examination of tumor tissue, a reverse connection between HIF-1α and HAF expression was uncovered, while a linear link emerged between HIF-2α and HAF expression. Overall, this study established that HIF-1α, HIF-2α, and HAF expression are associated with an unfavorable prognosis.

Ligusticum chuanxiong promotes the angiogenesis of preovulatory follicles (F1–F3) in late-phase laying hens

Ligusticum chuanxiong (CX) is a traditional Chinese medicine that is widely planted throughout the world. CX is one of the most important and commonly used drugs to enhance blood circulation. The preovulatory follicles in laying hens have a large number of blood arteries and meridians that feed the follicles' growth and maturation with nutrients, hormones, and cytokines. With the extension of laying time, preovulatory follicles angiogenesis decreased gradually. In this study, we studied the mechanism of CX on preovulatory follicles angiogenesis in late-phase laying hens. The results show that CX extract can increase the angiogenesis of preovulatory follicles (F1-F3) of late-phase laying hens. CX extract can promote vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation in preovulatory follicles theca layers, promote the proliferation, invasion and migration through PI3K/AKT and RAS/ERK signaling pathways in primary follicle microvascular endothelial-like cells (FMECs). In addition, CX extract can up-regulate the expression of hypoxia inducible factor α (HIF1α) in granulosa cells (GCs) and granulosa layers through PI3K/AKT and RAS/ERK signaling pathways, thereby promoting the secretion of vascular endothelial growth factor A (VEGFA). In conclusion, the current study confirmed the promoting effect of CX extract on the preovulatory follicles angiogenesis, which sets the stage for the design of functional animal feed for late-phase laying hens.

NARF is a hypoxia-induced coactivator for OCT4-mediated breast cancer stem cell specification.

Hypoxia is a key characteristic of the breast cancer microenvironment that promotes expression of the transcriptional activator hypoxia-inducible factor 1 (HIF-1) and is associated with poor patient outcome. HIF-1 increases the expression or activity of stem cell pluripotency factors, which control breast cancer stem cell (BCSC) specification and are required for cancer metastasis. Here, we identify nuclear prelamin A recognition factor (NARF) as a hypoxia-inducible, HIF-1 target gene in human breast cancer cells. NARF functions as an essential coactivator by recruiting the histone demethylase KDM6A to OCT4 bound to genes encoding the pluripotency factors NANOG, KLF4, and SOX2, leading to demethylation of histone H3 trimethylated at lysine-27 (H3K27me3), thereby increasing the expression of NANOG, KLF4, and SOX2, which, together with OCT4, mediate BCSC specification. Knockdown of NARF significantly decreased the BCSC population in vitro and markedly impaired tumor initiation capacity and lung metastasis in orthotopic mouse models.

Targeting HIF-2α for the Treatment of CML By Affecting LSCs Metabolism and the Vascular Microenvironment

Although the advent of tyrosine kinase inhibitors (TKI) drugs significantly increased the long-term survival of chronic myeloid leukemia (CML), residual LSCs can still lead to drug resistance and disease recurrence. As LSCs in CML rely on hypoxia-inducible factors (HIF) to maintain their own energy metabolism in the hypoxic environment of bone marrow, HIF-2α has not been systematically explored in CML. Here, we explored how HIF-2α participated in drug resistance and provided a potential new clinical strategy for CML. We first investigated the expression of HIF in the database and found the overexpression of HIF-2α in the bone marrow of CML patients compared with normal subjects, while there was no difference in HIF-1α and HIF-3α (Fig. 1A-B). We then collected bone marrow samples from normal subjects and CML patients. We found that compared with normal hematopoietic stem cells (Lin-CD90+CD34+CD38-), CML LSCs (Lin-CD90+CD34+CD38-) had higher levels of HIF-related proteins than common leukemia cells (Fig. 1C). To further explore the role of HIF-2α in the pathogenesis of CML, we constructed HIF-2α conditional knockout mice through transfecting the plasmid of Cre-BCR-ABL-GFP with transposase and Ctrl-BCR-ABL-GFP without transposition to HSPCs (Fig. 2A). After the first round of leukemia transplantation, the onset of CML was delayed in the HIF-2α knockout mice and the median survival time was prolonged from 31d in the Ctrl group to 60d (Fig. 2B). Next, we harvested fully onset CML mice for the secondary transplantation and found the median survival time extended from 46d to 117d in the HIF-2α knockout group (Fig. 2C). Then we investigate the biological function of HIF-2α in CML LSCs. We performed the clone formation assay on bone marrow cells of the first round of onset CML mice and found that HIF-2α knockout reduced the colony-forming ability of CML cells (Fig. 3A). To explore the tumorigenic ability of HIF-2α knockout, limiting dilution assay (LDA) was performed and found that the LSCs ratio of CML decreased by 30 times after HIF-2α knockout, from 1/76960 to 1/2237970 (Figure. 3B). Meanwhile, we explored the effect of HIF-2α knockout on the chemosensitivity in CML. TKI treatment combined with HIF-2α knockout can significantly improve the efficacy of TKI and extend the mouse survival time (Figure. 3C). To explore the specific mechanism by which HIF2A affects LSCs, we firstly investigate the effect of HIF-2α on LSCs metabolism. We detected metabolism-related indexes of LSCs in the CML model and found that the glycolysis ability of LSCs was weakened after HIF-2α knockout (Fig. 4A). At the same time, its oxidative phosphorylation pathway and reactive oxygen species (ROS) were enhanced (Fig. 4B-C) which may be an important cause of LSCs apoptosis. As HIF-2α can directly promote the transcription of pro-angiogenic factors, we detected the content of vascular endothelial growth factor (VEGF) α in the supernatant of mice bone marrow and found that it was significantly increased after the onset of CML but decreased after HIF-2α knockout (Fig. 5A). Fluorescent staining of bone marrow sections revealed that the density of blood vessels in bone marrow increased, whether in the intima (Fig. 5B) after the onset of CML. Next, we treated CML mice with VEGF Monoclonal antibody and found that it alone could prolong the survival time. However, the VEGF Monoclonal antibody did not affect HIF-2α knockout CML mice (Fig. 5C). These results suggest that HIF-2α is involved in bone marrow vascular remodelling after the onset of CML. To investigate the functional effect of HIF-2α in human CML, the CDX CML mouse model was made with CML cell lines (K562 and MEG-01) to observe the tumorigenesis of CML in nude mice, and they were treated with TKI. We found that HIF-2α knockout could delay the onset of CML and improve the therapeutic effect of TKI (Fig. 6A). To better apply the effect of HIF-2α on CML chemosensitivity to the clinic, we explored the effect of inhibitors of HIF, PT2399, on CML chemosensitivity. PT2399 can significantly increase the chemosensitivity of CML cell lines to TKIs and prolong the survival curve of CML mice treated with TKIs (Fig. 6B). In conclusion, HIF-2α knockout could inhibit the function of LSCs by affecting their metabolic pattern and vascular microenvironment in CML. Therefore, targeting HIF-2α may become a new strategy, and its specific inhibitor PT2399 may be a candidate drug for clinical application in CML treatment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Carbonic Anhydrase IX as a Marker of Disease Severity in Obstructive Sleep Apnea.

Background and Objectives: Carbonic anhydrase (CA) enzymes are a family of metalloenzymes that contain a zinc ion in their active sites. CA enzymes have been implied in important situations such as CO2 transport, pH regulation, and oncogenesis. CA-IX is a transmembrane glycoprotein and stimulates the expression of hypoxia-inducible factor-1 (HIF-1) CA-IX. This study aimed to determine serum CA-IX levels in OSA patients in whom intermittent hypoxia is important and to investigate the relationship between serum CA-IX levels and disease severity. Materials and Methods: The study included 88 people who applied to Malatya Turgut Özal University Training and Research Hospital Sleep Disorders Center without a history of respiratory disease, malignancy, and smoking. Patients were divided into three groups: control (AHI &lt; 5, n = 31), mild-moderate OSA (AHI = 5-30, n = 27) and severe OSA (AHI &gt; 30, n = 30). The analysis of the data included in the research was carried out with the SPSS (IBM Statistics 25, NY, USA). The Shapiro-Wilk Test was used to check whether the data included in the study had a normal distribution. Comparisons were made with ANOVA in multivariate groups and the t-test in bivariate groups. ANCOVA was applied to determine the effect of the CA-IX parameter for OSA by controlling the effect of independent variables. The differentiation in CA-IX and OSA groups was analyzed regardless of BMI, age, gender, and laboratory variables. ROC analysis was applied to determine the parameter cut-off point. Sensitivity, specificity, and cut-off were calculated, and the area under the curve (AUC) value was calculated. Results: Serum CA-IX levels were 126.3 ± 24.5 pg/mL in the control group, 184.6 ± 59.1 pg/mL in the mild-moderate OSA group, and 332.0 ± 39.7 pg/mL in the severe OSA group. Serum CA-IX levels were found to be higher in the severe OSA group compared to the mild-moderate OSA group and control group and higher in the mild-moderate OSA group compared to the control group (p &lt; 0.001, p &lt; 0.001, p &lt; 0.001, respectively). In addition, a negative correlation between CA-IX and minimum SaO2 and mean SaO2 (r = -0.371, p = 0.004; r = -0.319, p = 0.017, respectively). A positive correlation between CA-IX and desaturation index (CT90) was found (r = 0.369, p = 0.005). A positive correlation was found between CA-IX and CRP (r = 0.340, p = 0.010). When evaluated by ROC curve analysis, the area under the curve (AUC) value was determined as 0.940 (95% CI 0.322-0.557; p &lt; 0.001). When the cut-off value for CA-IX was taken as 254.5 pg/mL, it was found to have 96.7% sensitivity and 94.8% specificity in demonstrating severe OSA. Conclusions: Our study found that serum CA-IX value was higher in OSA patients than in control patients, and this elevation was associated with hypoxemia and inflammation. CA-IX value can be a fast, precise, and useful biomarker to predict OSA.

Neurovascular responses to neuronal activity during sensory development.

Understanding the development of intercellular communication in sensory regions is relevant to elucidate mechanisms of physiological and pathological responses to oxygen shortage in the newborn brain. Decades of studies in laboratory rodents show that neuronal activity impacts sensory maturation during two periods of postnatal development distinguished by the maturation of accessory structures at the sensory periphery. During the first of these developmental periods, angiogenesis is modulated by neuronal activity, and physiological levels of neuronal activity cause local tissue hypoxic events. This correlation suggests that neuronal activity is upstream of the production of angiogenic factors, a process that is mediated by intermittent hypoxia caused by neuronal oxygen consumption. In this perspective article we address three theoretical implications based on this hypothesis: first, that spontaneous activity of sensory neurons has properties that favor the generation of intermittent tissue hypoxia in neonate rodents; second, that intermittent hypoxia promotes the expression of hypoxia inducible transcription factors (HIFs) in sensory neurons and astrocytes; and third, that activity-dependent production of angiogenic factors is involved in pathological oxygen contexts.

A Novel Mitochondria-Targeting Iron Chelator Neuroprotects Multimodally via HIF-1 Modulation Against a Mitochondrial Toxin in a Dopaminergic Cell Model of Parkinson's Disease.

Coumarins are plant-derived polyphenolic compounds belonging to the benzopyrones family, possessing wide-ranging pharmaceutical applications including cytoprotection, which may translate into therapeutic potential for multiple diseases, including Parkinson's disease (PD). Here we demonstrate the neuroprotective potential of a new polyhydroxyl coumarin, N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetamide (CT51), against the mitochondrial toxin 1-methyl-4-phenylpyridinium (MPP+). MPP+'s mechanism of toxicity relates to its ability to inhibit complex Iof the mitochondrial electron transport chain (METC), leading to adenosine triphosphate (ATP) depletion, increased reactive oxygen species (ROS) production, and apoptotic cell death, hence mimicking PD-related neuropathology. Dopaminergic differentiated human neuroblastoma cells were briefly pretreated with CT51, followed by toxin exposure. CT51 significantly restored somatic cell viability and neurite processes; hence, the drug targets cell bodies and axons thereby preserving neural function and circuitry against PD-related damage. Moreover, MPP+ emulates the iron dyshomeostasis affecting dopaminergic neurons in PD-affected brains, whilst CT51 was previously revealed as an effective iron chelator that preferentially partitions to mitochondria. We extend these findings by characterising the drug's interactive effects at the METC level. CT51 did not improve mitochondrial coupling efficiency. However, voltammetricmeasurements and high-resolution respirometry analysis revealed that CT51 acts as an antioxidant agent. Also, the neuronal protection afforded by CT51 associated with downregulating MPP+-induced upregulated expression of hypoxia-inducible factor 1 alpha (HIF-1α), a protein which regulates iron homeostasis and protects against certain forms of oxidative stress after translocating to mitochondria.Our findings support the further development of CT51 as a dual functioning iron chelator and antioxidant antiparkinsonian agent.

Iron metabolism disorder regulated by BMP signaling in hypoxic pulmonary hypertension

Backgrounds and aimsUnexplained iron deficiency is associated with poorer survival in patients with pulmonary hypertension (PH). Bone morphogenetic protein (BMP) signaling and BMP protein type II receptor (BMPR2) expression are important in the pathogenesis of PH. BMP6 in hepatocytes is a central transcriptional regulator of the iron hormone hepcidin that controls systemic iron balance. This study aimed to investigate the effects of BMP signaling on iron metabolism and its implication in hypoxia-induced PH. Methods and resultsPH was induced in Sprague–Dawley Rats under hypoxia for 4 weeks. Compared with the control group, right ventricular systolic pressure and right ventricle hypertrophy index were both markedly increased, and serum iron level was significantly decreased with iron metabolic disorder in the hypoxia group. In cultured human pulmonary artery endothelial cells (HPAECs), hypoxia increased oxidative stress and apoptosis, which were reversed by supplementation with Fe agent. Meanwhile, iron chelator deferoxamine triggered oxidative stress and apoptosis in HPAECs, and treatment with antioxidant alleviated iron-deficiency-induced apoptosis by reducing reactive oxygen species production. Expression of hepcidin, BMP6 and hypoxia-inducible factor (HIF)-1α were significantly upregulated, while expression of BMPR2 was downregulated in hepatocytes in the hypoxia group, both in vivo and in vitro. Expression of hepcidin and HIF-1α were significantly increased by BMP6, while pretreatment with siRNA-BMPR2 augmented the enhanced expression of hepcidin and HIF-1α induced by BMP6. ConclusionsIron deficiency promoted oxidative stress and apoptosis in HPAECs in hypoxia-induced PH, and enhanced expression of hepcidin regulated by BMP6/BMPR2 signaling may contribute to iron metabolic disorder.