Expression Of Hypoxia-inducible Factor Research Articles

Hypoxia with or without Treadmill Exercises Affects Slow-Twitch Muscle Atrophy and Joint Destruction in a Rat Model of Rheumatoid Arthritis.

The effects of treadmill running under hypoxic conditions on joints and muscles of collagen-induced arthritis (CIA) rats were investigated. CIA rats were divided into normoxia no-exercise, hypoxia no-exercise (Hypo-no), and hypoxia exercise (Hypo-ex) groups. Changes were examined on days 2 and 44 of hypoxia with or without treadmill exercises. In the early stage of hypoxia, the expression of hypoxia-inducible factor (HIF)-1α increased in the Hypo-no and Hypo-ex groups. The expression of the egl-9 family hypoxia-inducible factor 1 (EGLN1) and vascular endothelial growth factor (VEGF) in the Hypo-ex group also increased. Under sustained hypoxia, the Hypo-no and Hypo-ex groups did not show increased expression of HIF-1α or VEGF, but p70S6K levels were elevated. Histologically, joint destruction was alleviated in the Hypo-no group, the loss of muscle weight in slow-twitch muscles was prevented, and muscle fibrosis was suppressed. In the Hypo-ex group, the preventive effect of a reduction in the slow-twitch muscle cross-sectional area was enhanced. Thus, chronic hypoxia in an animal model of rheumatoid arthritis controlled arthritis and joint destruction and prevented slow-twitch muscle atrophy and fibrosis. The combination of hypoxia with treadmill running further enhanced the preventive effects on slow-twitch muscle atrophy.

Insufficient oxygen inhalation during cardiopulmonary resuscitation induces early changes in hemodynamics followed by late and unfavorable systemic responses in post-cardiac arrest rats.

Cardiac arrest (CA) and concomitant post-CA syndrome lead to a lethal condition characterized by systemic ischemia-reperfusion injury. Oxygen (O2 ) supply during cardiopulmonary resuscitation (CPR) is the key to success in resuscitation, but sustained hyperoxia can produce toxic effects post CA. However, only few studies have investigated the optimal duration and dosage of O2 administration. Herein, we aimed to determine whether high concentrations of O2 at resuscitation are beneficial or harmful. After rats were resuscitated from the 10-min asphyxia, mechanical ventilation was restarted at an FIO2 of 1.0 or 0.3. From 10 min after initiating CPR, FIO2 of both groups were maintained at 0.3. Bio-physiological parameters including O2 consumption (VO2 ) and mRNA gene expression in multiple organs were evaluated. The FIO2 0.3 group decreased VO2 , delayed the time required to achieve peak MAP, lowered ejection fraction (75.1 ± 3.3% and 59.0 ± 5.7% with FIO2 1.0 and 0.3, respectively; p < .05), and increased blood lactate levels (4.9 ± 0.2 mmol/L and 5.6 ± 0.2 mmol/L, respectively; p < .05) at 10 min after CPR. FIO2 0.3 group had significant increases in hypoxia-inducible factor, inflammatory, and apoptosis-related mRNA gene expression in the brain. Likewise, significant upregulations of hypoxia-inducible factor and apoptosis-related gene expression were observed in the FIO2 0.3 group in the heart and lungs. Insufficient O2 supplementation in the first 10 min of resuscitation could prolong ischemia, and may result in unfavorable biological responses 2 h after CA. Faster recovery from the impairment of O2 metabolism might contribute to the improvement of hemodynamics during the early post-resuscitation phase; therefore, it may be reasonable to provide the maximum feasible O2 concentrations during CPR.

Anti-tumor Effects of Cisplatin Synergist in Combined Treatment with Clostridium novyi-NT Spores Against Hypoxic Microenvironments in a Mouse Model of Cervical Cancer Caused by TC-1 Cell Line.

Despite the development of anti-human papillomavirus (HPV) vaccines, cervical cancer is still a common disease in women, especially in developing countries. The presence of a hypoxic microenvironment causes traditional treatments to fail. In this study, we presented a combined treatment method based on the chemotherapeutic agent cisplatin and Clostridium novyi-NT spores to treat normoxic and hypoxic areas of the tumor. TC-1 Cell line capable of expressing HPV-16 E6/7 oncoproteins was subcutaneously transplanted into female 6-8 week old C57/BL6 mice. The tumor-bearing mice were randomly divided into four groups and treated with different methods after selecting a control group. Group 1: Control without treatment (0.1 mL sterile PBS intratumorally), Group: C. novyi-NT (107 C. novyi-NT). Group 3: Receives cisplatin intraperitoneally (10 mg/kg). Fourth group: Intratumoral administration of C. novyi-NT spores + intraperitoneal cisplatin. Western blot analysis was used to examine the effects of anti-hypoxia treatment and expression of hypoxia-inducible factor 1 (HIF-1) and vascular endothelial growth factor (VEGF) proteins. The results clearly showed that combined treatment based on C. novyi-NT and cisplatin significantly reduced the expression of HIF-1 alpha and VEGF proteins compared to cisplatin alone. At the same time, the amount of necrosis of tumor cells in the combined treatment increased significantly compared to the single treatment and the control. At the same time, the mitotic count decreased significantly. Our research showed that developing a combined treatment method based on C. novyi-NT and cisplatin against HPV-positive cervical cancer could overcome the treatment limitations caused by the existence of hypoxic areas of the tumor.

Oxygen levels at the time of activation determine T cell persistence and immunotherapeutic efficacy.

Oxygenation levels are a determinative factor in T cell function. Here we describe that the oxygen tensions sensed by mouse and human T cells at the moment of activation act to persistently modulate both differentiation and function. We found that in a protocol of CAR-T cell generation, 24 hours of low oxygen levels during initial CD8+ T cell priming is sufficient to enhance antitumour cytotoxicity in a preclinical model. This is the case even when CAR-T cells are subsequently cultured under high oxygen tensions prior to adoptive transfer. Increased hypoxia inducible transcription factor (HIF) expression was able to alter T cell fate in a similar manner to exposure to low oxygen tensions; however, only a controlled or temporary increase in HIF signalling was able to consistently improve cytotoxic function of T cells. These data show that oxygenation levels during and immediately after T cell activation play an essential role in regulating T cell function.

The Role of Hypoxia and Cancer Stem Cells in Development of Glioblastoma.

Glioblastoma multiform (GBM) is recognized as the most malignant brain tumor with a high level of hypoxia, containing a small population of glioblastoma stem like cells (GSCs). These GSCs have the capacity of self-renewal, proliferation, invasion and recapitulating the parent tumor, and are major causes of radio-and chemoresistance of GBM. Upregulated expression of hypoxia inducible factors (HIFs) in hypoxia fundamentally contributes to maintenance and progression of GSCs. Therefore, we thoroughly reviewed the currently acknowledged roles of hypoxia-associated GSCs in development of GBM. In detail, we recapitulated general features of GBM, especially GSC-related features, and delineated essential responses resulted from interactions between GSC and hypoxia, including hypoxia-induced signatures, genes and pathways, and hypoxia-regulated metabolic alterations. Five hypothesized GSC niches are discussed and integrated into one comprehensive concept: hypoxic peri-arteriolar niche of GSCs. Autophagy, another protective mechanism against chemotherapy, is also closely related to hypoxia and is a potential therapeutic target for GBM. In addition, potential causes of therapeutic resistance (chemo-, radio-, surgical-, immuno-), and chemotherapeutic agents which can improve the therapeutic effects of chemo-, radio-, or immunotherapy are introduced and discussed. At last, as a potential approach to reverse the hypoxic microenvironment in GBM, hyperbaric oxygen therapy (HBOT) might be an adjuvant therapy to chemo-and radiotherapy after surgery. In conclusion, we focus on demonstrating the important role of hypoxia on development of GBM, especially by affecting the function of GSCs. Important advantages have been made to understand the complicated responses induced by hypoxia in GBM. Further exploration of targeting hypoxia and GSCs can help to develop novel therapeutic strategies to improve the survival of GBM patients.

Impact of maternal protein restriction on Hypoxia-Inducible Factor (HIF) expression in male fetal kidney development.

Kidney developmental studies have demonstrated molecular pathway changes that may be related to decreased nephron numbers in the male 17 gestational days (17GD) low protein (LP) intake offspring compared to normal protein intake (NP) progeny. Here, we evaluated the HIF-1 and components of its pathway in the kidneys of 17-GD LP offspring to elucidate the molecular modulations during nephrogenesis. Pregnant Wistar rats were allocated into two groups: NP (regular protein diet-17%) or LP (Low protein diet-6%). Taking into account miRNA transcriptome sequencing previous study (miRNA-Seq) in 17GD male offspring kidneys investigated predicted target genes and proteins related to the HIF-1 pathway by RT-qPCR and immunohistochemistry. In the present study, in male 17-GD LP offspring, an increased elF4, HSP90, p53, p300, NFκβ, and AT2 gene encoding compared to the NP progeny. Higher labeling of HIF-1α CAP cells in 17-DG LP offspring was associated with reduced elF4 and phosphorylated elF4 immunoreactivity in LP progeny CAP cells. In 17DG LP, the NFκβ and HSP90 immunoreactivity was enhanced, particularly in the CAP area. The current study supported that the programmed reduced nephron number in the 17-DG LP offspring may be related to changes in the HIF-1α signaling pathway. Factors that facilitate the transposition of HIF-1α to progenitor renal cell nuclei, such as increased NOS, Ep300, and HSP90 expression, may have a crucial role in this regulatory system. Also, HIF-1α changes could be associated with reduced transcription of elF-4 and its respective signaling path.

Intermittent Hypoxic Preconditioning Plays a Cardioprotective Role in Doxorubicin-Induced Cardiomyopathy.

Intermittent hypoxic preconditioning (IHP) is a well-established cardioprotective intervention in models of ischemia/reperfusion injury. Nevertheless, the significance of IHP in different cardiac pathologies remains elusive. In order to investigate the role of IHP and its effects on calcium-dependent signalization in HF, we employed a model of cardiomyopathy induced by doxorubicin (Dox), a widely used drug from the class of cardiotoxic antineoplastics, which was i.p. injected to Wistar rats (4 applications of 4mg/kg/week). IHP-treated group was exposed to IHP for 2weeks prior to Dox administration. IHP ameliorated Dox-induced reduction in cardiac output. Western blot analysis revealed increased expression of sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) while the expression of hypoxia inducible factor (HIF)-1-α, which is a crucial regulator of hypoxia-inducible genes, was not changed. Animals administered with Dox had further decreased expression of TRPV1 and TRPV4 (transient receptor potential, vanilloid subtype) ion channels along with suppressed Ca2+/calmodulin-dependent protein kinase II (CaMKII) activation. In summary, IHP-mediated improvement in cardiac output in the model of Dox-induced cardiomyopathy is likely a result of increased SERCA2a expression which could implicate IHP as a potential protective intervention in Dox cardiomyopathy, however, further analysis of observed effects is still required.

Submersion and hypoxia inhibit alveolar epithelial Na+ transport through ERK/NF-κB signaling pathway

BackgroundHypoxia is associated with many respiratory diseases, partly due to the accumulation of edema fluid and mucus on the surface of alveolar epithelial cell (AEC), which forms oxygen delivery barriers and is responsible for the disruption of ion transport. Epithelial sodium channel (ENaC) on the apical side of AEC plays a crucial role to maintain the electrochemical gradient of Na+ and water reabsorption, thus becomes the key point for edema fluid removal under hypoxia. Here we sought to explore the effects of hypoxia on ENaC expression and the further mechanism related, which may provide a possible treatment strategy in edema related pulmonary diseases.MethodsExcess volume of culture medium was added on the surface of AEC to simulate the hypoxic environment of alveoli in the state of pulmonary edema, supported by the evidence of increased hypoxia-inducible factor-1 expression. The protein/mRNA expressions of ENaC were detected, and extracellular signal-regulated kinase (ERK)/nuclear factor κB (NF-κB) inhibitor was applied to explore the detailed mechanism about the effects of hypoxia on epithelial ion transport in AEC. Meanwhile, mice were placed in chambers with normoxic or hypoxic (8%) condition for 24 h, respectively. The effects of hypoxia and NF-κB were assessed through alveolar fluid clearance and ENaC function by Ussing chamber assay.ResultsHypoxia (submersion culture mode) induced the reduction of protein/mRNA expression of ENaC, whereas increased the activation of ERK/NF-κB signaling pathway in parallel experiments using human A549 and mouse alveolar type 2 cells, respectively. Moreover, the inhibition of ERK (PD98059, 10 µM) alleviated the phosphorylation of IκB and p65, implying NF-κB as a downstream pathway involved with ERK regulation. Intriguingly, the expression of α-ENaC could be reversed by either ERK or NF-κB inhibitor (QNZ, 100 nM) under hypoxia. The alleviation of pulmonary edema was evidenced by the administration of NF-κB inhibitor, and enhancement of ENaC function was supported by recording amiloride-sensitive short-circuit currents.ConclusionsThe expression of ENaC was downregulated under hypoxia induced by submersion culture, which may be mediated by ERK/NF-κB signaling pathway.

Three-dimensional core-shell alginate microsphere for cancer hypoxia simulation in vitro.

Hypoxia is one of the major causes of cancer resistance and metastasis. Currently, it is still lack of convenient ways to simulate the in vivo hypoxic tumor microenvironment (TME) under normoxia in vitro. In this study, based on multi-polymerized alginate, we established a three-dimensional culture system with a core-shell structure (3d-ACS), which prevents oxygen diffusion to a certain extent, thereby simulating the hypoxic TME in vivo. The cell activity, hypoxia inducible factor (HIF) expression, drug resistance, and the related gene and protein changes of the gastric cancer (GC) cells were investigated in vitro and in vivo. The results demonstrated that the GC cells formed organoid-like structures in the 3d-ACS and manifested more aggressive growth and decreased drug responses. Our study provides an accessible hypoxia platform in the laboratory with moderate configuration and it may be applied in studies of the hypoxia-induced drug resistances and other preclinical fields.

HIF 1 α - a promising target for the treatment of meningiomas.

Meningiomas are the most frequent tumors of the brain and spinal cord with a potency to recur in around one third of the cases and and invade surrounding tissue. Hypoxia driven factors like HIFs (Hypoxia inducible factors) are implicated in tumor cell growth and proliferation. This study aims at determining the association of HIF 1 α with different histopathological grades and types of meningiomas. This prospective study was conducted on 35 patients. The patients presented with headache (65.71%), seizures (22.86%) and neurological deficits (11.43%). They underwent surgical excision and surgical tissue samples of these patients were histopathologically processed and microscopically graded and typed. Immunohistochemistry was performed using anti-HIF 1α monoclonal antibody. The nuclear expression of HIF 1 α was graded as <10%: negative, 11-50%: mild to moderate positive, >50%: strong positive. Of the 35 cases so examined 20% were recurrent; 74.29% were WHO grade I with meningothelial type (22.86%), being the commonest; 57.14 % revealed mild to moderate positivity for HIF 1α, while strong positivity was noted in 28.57%. Significant association was found between WHO grade and HIF 1α (p=0.0015) and between histopathological types and HIF 1α (p=0.0433). Furthermore, HIF 1α was also significantly associated with the recurrent cases (p=0.0172). HIF 1α appears to be a marker and a promising target for effective therapeutics in meningiomas.

Targeting hPKM2 in cancer: A bio isosteric approach for ligand design

The term cancer refers to a plethora of diseases characterized by the development of abnormal cells that divide uncontrollably and can infiltrate further proximal or distal body tissues. Each type of cancer can be defined by aggressiveness, localization, metabolism, and response to available treatments. Among the most common hallmarks of cancer is a more acidic intracellular microenvironment. Offset pH values are due to an excess of lactate and an increased hypoxia-inducible factor (HIF) expression, which leads to a hypoxic state and a metabolic shift towards glycolysis to produce adenosine-5′-triphosphate (ATP) necessary for cellular metabolism. Warburg's hypothesis underpins this concept, making glycolysis and its central enzyme pyruvate kinase (hPKM2), an ideal target for drug development. Using molecular docking and extensive molecular dynamics (MD) simulations we investigated the binding mode of phosphoenolpyruvate (PEP) inside the hPKM2 active site, and then evaluated a set of known bio-isosteric inhibitors to understand the differences caused by their substitutions on their binding mode. Ultimately, we propose a new molecular entity to hamper hPKM2, unbalance cellular energy, and possibly trigger autophagic mechanisms.

Circ‐myh8 Promotes Pulmonary Hypertension by Recruiting KAT7 to Govern Hypoxia‐Inducible Factor‐1α Expression

Background Aberrant expression of circular RNAs (circRNAs) contributes to the initiation and progression of pulmonary hypertension (PH). Hypoxia-inducible factor (HIF) is a well-known modulator of hypoxia-induced PH. The role and underlying mechanism of circRNAs in the regulation of HIF expression remains elusive. Methods and Results We profiled pulmonary artery transcriptomes using RNA sequencing and screened circRNAs associated with hypoxia treatment. The expression of a novel circRNA, circ_chr11_67292179-67294612 (circ-myh8), was increased by hypoxia in a time-dependent manner. We evaluated the effects of circ-myh8 overexpression by adeno-associated virusor inhibition by short hairpin RNA on proliferation and cell cycling in mice and pulmonary artery smooth muscle cells. Overexpression of circ-myh8 promotes PH under normoxia, and disruption of circ-myh8 by short hairpin RNA mitigates PH in chronic hypoxic mice. Biologically, circ-myh8 induces the proliferation and cell-cycle progression of pulmonary artery smooth muscle cells in vivo and in vitro. Mechanistically, RNA pull-down and RNA immunoprecipitation assays were used to examine the interaction of circRNAs with the binding protein KAT7 (lysine acetyltransferase 7). The acetylation level of lysine 5 of histone H4 in the transcriptional initiation region of HIF1α was determined by chromatin immunoprecipitation assay followed by reverse transcription-quantitativepolymerase chain reaction. Circ-myh8 acts as a modular scaffold to recruit histone acetyltransferase KAT7 to the promoters of HIF1α, which elicits acetylation of lysine 5 of histone H4 in their promoters. Conclusions Our findings not only reveal the pivotal roles of circ-myh8 in governing histone modification in anti-PH treatment but also advocate triggering the circ-myh8/KAT7/HIF1α pathway to combat PH.

Allantopyrone A interferes with the degradation of hypoxia-inducible factor 1α protein by reducing proteasome activity in human fibrosarcoma HT-1080 cells.

Allantopyrone A is an α-pyrone metabolite that was originally isolated from the endophytic fungus Allantophomopsis lycopodina KS-97. We previously demonstrated that allantopyrone A exhibits anti-cancer, anti-inflammatory, and neuroprotective activities. In the present study, we showed that allantopyrone A up-regulated the protein expression of hypoxia-inducible factor (HIF)-1α in human fibrosarcoma HT-1080 cells. It also up-regulated the mRNA expression of BNIP3 and ENO1, but not other HIF target genes or HIF1A. Allantopyrone A did not inhibit the prolyl hydroxylation of HIF-1α, but enhanced the ubiquitination of cellular proteins. Consistent with this result, chymotrypsin-like and trypsin-like proteasome activities were reduced, but not completely inactivated by allantopyrone A. Allantopyrone A decreased the amount of proteasome catalytic subunits. Therefore, the present results showed that allantopyrone A interfered with the degradation of HIF-1α protein by reducing proteasome activity in human fibrosarcoma HT-1080 cells.

Laminin switches terminal differentiation fate of human trophoblast stem cells under chemically defined culture conditions

Human trophoblast stem cells (hTSCs) have emerged as a powerful tool to model early placental development invitro. Analogous to the epithelial cytotrophoblast in the placenta, hTSCs can differentiate into cells of the extravillous trophoblast (EVT) lineage or the multinucleate syncytiotrophoblast (STB). Here we present a chemically defined culture system for STB and EVT differentiation of hTSCs. Notably, in contrast to current approaches, we neither utilize forskolin for STB formation nor transforming growth factor-beta (TGFβ) inhibitors or a passage step for EVT differentiation. Strikingly, the presence of a single additional extracellular cue-laminin-111-switched the terminal differentiation of hTSCs from STB to the EVT lineage under these conditions. In the absence of laminin-111, STB formation occurred, with cell fusion comparable to that obtained with differentiation mediated by forskolin; however, in the presence of laminin-111, hTSCs differentiated to the EVT lineage. Protein expression of nuclear hypoxia-inducible factors (HIF1α and HIF2α) was upregulated during EVT differentiation mediated by laminin-111 exposure. A heterogeneous mixture of Notch1+ EVTs in colonies and HLA-G+ single-cell EVTs were obtained without a passage step, reminiscent of heterogeneity invivo. Further analysis showed that inhibition of TGFβ signaling affected both STB and EVT differentiation mediated by laminin-111 exposure. TGFβ inhibition during EVT differentiation resulted in decreased HLA-G expression and increased Notch1 expression. On the other hand, TGFβ inhibition prevented STB formation. The chemically defined culture system for hTSC differentiation established herein facilitates quantitative analysis of heterogeneity that arises during hTSC differentiation and will enable mechanistic studies invitro.

Inhibitory effect of miR-138-5p on choroidal fibrosis in lens-induced myopia guinea pigs via suppressing the HIF-1α signaling pathway

Myopia is one of the most common eye diseases in children and adolescents worldwide. Currently, there is no effective treatment in clinical practice. Ocular tissue fibrosis is involved in the development of myopia and this study aimed to investigate the effect of miR-138-5p on choroidal fibrosis in myopic guinea pigs via regulating the HIF-1α signaling pathway. First, guinea pigs were randomly divided into a normal control (NC) group, a lens-induced myopia (LIM) group, a LIM + miR-138-5p-carried Lentivirus treatment (LV) group, and a LIM + miR-138-5p-Vector treatment (VECTOR) group. All animals were induced experimental myopia with a −6.0 diopter lens except those in the NC group. Meanwhile, animals in the LV group were supplemented with 5 μl of miR-138-5p-carried Lentivirus, while those in the VECTOR group were only supplemented with the same volume of miR-138-5p-Vector. After myopia induction for 2 and 4 weeks, the refractive status and other ocular parameters of the guinea pigs were measured. Further, the expression of hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β, collagen I, hydroxyproline (HYP), interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and a-smooth muscle actin (α-SMA) in choroidal tissues was investigated. Results showed that the refraction and axial length of the experimental myopic guinea pigs increased, and choroid fibrosis aggravated after experimental myopic induction. miR-138-5p can efficiently decrease the refraction and ocular length, and ameliorate the choroidal fibrosis of the experimental myopic guinea pigs via downregulating the fibrosis-related TGF-β1, collagen I, HYP, IL-1β, TNF-α, and α-SMA expression through inhibiting the HIF-1α signaling pathway. Our results provide new insight into controlling myopic development using microRNAs in clinical practice.

Inhibition of melanoma using a nanoceria-based prolonged oxygen-generating phototherapy hydrogel.

Tumor hypoxic environment is an inevitable obstacle for photodynamic therapy (PDT) of melanoma. Herein, a multifunctional oxygen-generating hydrogel loaded with hyaluronic acid-chlorin e6 modified nanoceria and calcium peroxide (Gel-HCeC-CaO2) was developed for the phototherapy of melanoma. The thermo-sensitive hydrogel could act as a sustained drug delivery system to accumulate photosensitizers (chlorin e6, Ce6) around the tumor, followed by cellular uptake mediated by nanocarrier and hyaluronic acid (HA) targeting. The moderate sustained oxygen generation in the hydrogel was produced by the reaction of calcium peroxide (CaO2) with infiltrated H2O in the presence of catalase mimetic nanoceria. The developed Gel-HCeC-CaO2 could efficiently alleviate the hypoxia microenvironment of tumors as indicated by the expression of hypoxia-inducible factor -1α (HIF-1α), meeting the "once injection, repeat irradiation" strategy and enhanced PDT efficacy. The prolonged oxygen-generating phototherapy hydrogel system provided a new strategy for tumor hypoxia alleviation and PDT.

Hypoxia-Induced Kidney Injury in Newborn Rats

Exposure to hypoxia during the early postnatal period can have adverse effects on vital organs. Neonatal Sprague-Dawley rats housed in a hypoxic chamber were compared to those in a normoxic chamber from postnatal days 0 to 7. Arterial blood was collected to evaluate renal function and hypoxia. Kidney morphology and fibrosis were evaluated using staining methods and immunoblotting. In the kidneys of the hypoxic group, protein expressions of hypoxia-inducible factor-1 were higher than those in the normoxic group. Hypoxic rats had higher levels of hematocrit, serum creatinine, and lactate than normoxic rats. Body weight was reduced, and protein loss of kidney tissue was observed in hypoxic rats compared to normoxic rats. Histologically, hypoxic rats showed glomerular atrophy and tubular injury. Renal fibrosis with collagen fiber deposition was observed in the hypoxic group. The expression of nicotinamide adenine dinucleotide phosphate oxidases was enhanced in the kidneys of hypoxic rats. Proteins involved in apoptosis were upregulated in the kidneys of hypoxic rats. An increase in the expression of pro-inflammatory cytokines was also observed in the kidneys of hypoxic rats. Hypoxic kidney injury in neonatal rats was associated with oxidative stress, inflammation, apoptosis, and fibrosis.

Histological analysis for pulp mineralisation after severe intrusive luxation of immature molars in rats.

Pulp mineralisation is a survival process that may occur in the pulp of immature teeth following trauma. However, the mechanism of this process remains unclear. The aim of this study was to evaluate the histological manifestations of pulp mineralisation after intrusion in immature molars of rats. Three-week-old male Sprague-Dawley rats were subjected to intrusive luxation of the right maxillary second molar by an impact force from a striking instrument through a metal force transfer rod. The left maxillary second molar of each rat was used as a control. The control and injured maxillae were collected at 3, 7, 10, 14, and 30 days after trauma (n=15 per time group) and evaluated using haematoxylin and eosin staining and immunohistochemistry. Independent two-tailed Student's t-test was used for statistical comparison of the immunoreactive area. Pulp atrophy and mineralisation were observed in 30%-40% of the animals, and no pulp necrosis occurred. Ten days after trauma, pulp mineralisation, with osteoid tissue rather than reparative dentin, formed around the newly vascularised areas in the coronal pulp. CD90-immunoreactive cells were observed in the sub-odontoblastic multicellular layer in control molars, whereas the number of these cells was decreased in the traumatised teeth. CD105 localised in cells around the pulp osteoid tissue of the traumatised teeth, whereas in control teeth, it was only expressed in the vascular endothelial cells of capillaries in the odontoblastic or sub-odontoblastic layers. In specimens with pulp atrophy at 3-10 days after trauma, hypoxia inducible factor expression and CD11b-immunoreactive inflammatory cells increased. Following intrusive luxation of immature teeth without crown fractures in rats, no pulp necrosis occurred. Instead, pulp atrophy and osteogenesis around neovascularisation with activated CD105-immunoreactive cells were observed in the coronal pulp microenvironment characterised by hypoxia and inflammation.

Transcriptional Response to Hypoxia: The Role of HIF-1-Associated Co-Regulators.

The Hypoxia Inducible Factor 1 (HIF-1) plays a major role in the cellular response to hypoxia by regulating the expression of many genes involved in adaptive processes that allow cell survival under low oxygen conditions. Adaptation to the hypoxic tumor micro-environment is also critical for cancer cell proliferation and therefore HIF-1 is also considered a valid therapeutical target. Despite the huge progress in understanding regulation of HIF-1 expression and activity by oxygen levels or oncogenic pathways, the way HIF-1 interacts with chromatin and the transcriptional machinery in order to activate its target genes is still a matter of intense investigation. Recent studies have identified several different HIF-1- and chromatin-associated co-regulators that play important roles in the general transcriptional activity of HIF-1, independent of its expression levels, as well as in the selection of binding sites, promoters and target genes, which, however, often depends on cellular context. We review here these co-regulators and examine their effect on the expression of a compilation of well-characterized HIF-1 direct target genes in order to assess the range of their involvement in the transcriptional response to hypoxia. Delineating the mode and the significance of the interaction between HIF-1 and its associated co-regulators may offer new attractive and specific targets for anticancer therapy.

FtMt reduces oxidative stress-induced trophoblast cell dysfunction via the HIF-1α/VEGF signaling pathway

BackgroundPreeclampsia (PE) is a complication of pregnancy that causes long-term adverse outcomes for the mother and fetus and may even lead to death. Oxidative stress caused by the imbalance of oxidants and antioxidants in the placenta has been considered as one of the key mechanisms of preeclampsia (together with inflammation, etc.), in which the placental mitochondria play an important role. The expression of hypoxia-inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF) is known to be increased in patients with PE. Mitochondrial ferritin (FtMt) is known to protect the mitochondria from oxidative stress, although its specific role in PE remains unclear.MethodsWe used qRT-PCR and western blotting to detect the expression levels of FtMt, HIF-1α, and VEGF in placental tissues from patients with PE. Human chorionic trophoblast cells were also administered with hypoxia treatment, followed by the detection of cell proliferation, invasion and angiogenic capacity by CCK8, Transwell, and endothelial cell angiogenesis assays; we also detected the expression of HIF-1α and VEGF in these cells. Finally, overexpression or inhibitory FtMt lentiviral vectors, along with negative control vectors, were constructed and transfected into hypoxia-treated human chorionic trophoblast cells; this was followed by analyses of cell function.ResultsThe expression levels of FtMt, HIF-1α and VEGF in the PE group were higher than those in the control group (P < 0.05). Following hypoxia, there was an increase in the expression levels of HIF-1α and VEGF protein in trophoblast cells. There was also an increase in invasion ability and vascular formation ability along with a reduction in cell proliferation ability. These effects were reversed by transfecting cells with the knockout FtMt lentivirus vector. The differences were statistically significant.ConclusionAnalyses showed that FtMt plays a key role in the vascular regulation of PE trophoblast cells after hypoxia possibly acting via the HIF-1α/VEGF signaling pathway. These results provide us an enhanced understanding of the pathogenesis of PE and suggest that the HIF-1α/VEGF signaling pathway represents a new target for the treatment of PE.