Hypoxia-induced apoptosis of mouse spermatocytes is mediated by HIF-1α through a death receptor pathway and a mitochondrial pathway

Plantaginis Herba attenuates adriamycin-induced nephropathy: Molecular mechanism insights by integrated transcriptomic and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese herbal Plantaginis Herba (PL) is one of the most widely used plants for both medicinal and dietary purposes. Plantaginis Herba is the main medicine used in a traditional Chinese prescription called Cheqiancao decoction, and it is known for its liver and kidney protective properties.

AIM OF THE STUDY

The aim of the present study was to explore the interventions and mechanisms of PL in ADR nephropathy by performing an integrated analysis of in vitro and in vivo experiments.

MATERIALS AND METHODS

The ingredients of PL were analysed by Ultra High Performance Liquid Chromatography (UPLC). The biochemical indicators of renal injury in the serum and urine were detected by a Micronumerase assay and ELISA. The renal histopathology and ultrastructure were analysed by H&E staining, Masson's trichrome staining and transmission electron microscopy (TEM), respectively. By identifying the targets of PL and ADR nephropathy, a network of PL-constituents-targets-ADR nephropathy was constructed, and a KEGG signaling pathway enrichment analysis was performed to complete the network pharmacology. A transcriptomic analysis was performed on a sequencing platform (Illumina).

RESULTS

Plantaginis Herba significantly decreased the levels of BUN, Scr, ALB, MAU and KIM-1. Plantaginis Herba inhibited renal histopathological injury and alleviate foot process fusion and podocyte basement membrane thickening. In addition, the results of the transcriptomic analysis and network pharmacology analysis indicated that the HIF-1, TGF-β, and PI3K/AKT signaling pathways; apoptosis; and ECM-receptor interactions might be pivotal pathways for the effect of the PL intervention on ADR nephropathy. Moreover, the validation results revealed that PL could effectively attenuate collagen fibre deposition and inhibit oxidative stress. Plantaginis Herba could regulate the expression levels of pivotal proteins in the β-catenin/TGF-β1, HIF-1, and PI3K signaling pathways in renal tissues. Plantaginis Herba could reduce the level of apoptosis and the percentage of decrease in the mitochondrial membrane potential (MMP) in primary renal cells from rats with ADR nephropathy, and regulate key proteins involved in mitochondrial apoptosis. Furthermore, Luteolin from PL had good affinity for HIF-1α, and the ability of Luteolin to ameliorate in ameliorating ADR-induced MPC-5 cell injury was attenuated by overexpressing HIF-1α.

CONCLUSIONS

Plantaginis Herba alleviates ADR-induced nephropathy by regulating mitochondrial apoptosis via the HIF-1α signaling pathway. Luteolin may be one of the active ingredients responsible for these effects, and these findings provide an innovative strategy for the intervention and treatment of ADR nephropathy.

From Hypoxia to Oxidative Stress: Antioxidants' Role to Reduce Male Reproductive Damage

Hypoxia is one of the main reasons causing male reproductive damage for people living in high altitude. Pathological evidences have been presented both in humans and animal models. Spermatogenesis disruption, worse sperm parameters, hormone disorder and erectile dysfunction are emblematic of male reproductive impairments brought by hypoxia. Among many mechanisms impairing male reproductive systems, oxidative stress is always a field of interest to explore. Although previous reviews have discussed about hypoxia or oxidative stress and antioxidants on male fertility respectively, no one has elucidated the concrete role of oxidative stress in hypoxia and correlating antioxidants that can ameliorate the negative effects. In this review, we firstly introduce hypoxia etiology and describe specific damage of hypoxia on male reproductive functions. Then, we emphasized interplays between hypoxia and oxidative stress as well as negative influences brought by oxidative stress. Finally, we listed antioxidants for oxidative stress and hypoxia-induced reproductive damage and discussed their controversial experimental effects for male infertility.

Integrative bioinformatics analysis to identify ferroptosis-related genes in non-obstructive azoospermia

PURPOSE

The objective of this study was to discern ferroptosis-related genes (FRGs) linked to non-obstructive azoospermia and investigate the associated molecular mechanisms.

METHOD

A dataset related to azoospermia was retrieved from the Gene Expression Omnibus database, and FRGs were sourced from GeneCards. Ferroptosis-related differentially expressed genes (FRDEGs) were discerned. Subsequently, these genes underwent analyses encompassing Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, as well as protein-protein interaction (PPI) networks and assessments of functional similarity. Following the identification of hub genes, an exploration of immune infiltration, single-cell expression, diagnostic utility, and interactions involving hub genes, RNA-binding proteins (RBPs), transcription factors (TFs), microRNAs (miRNAs), and drugs was conducted.

RESULTS

A total of 35 differentially expressed FRGs were discerned. These genes demonstrated enrichment in functions and pathways associated with ferroptosis. From the PPI network, eight hub genes were selected. Functional similarity analysis highlighted the potential pivotal roles of HMOX1 and GPX4 in azoospermia. Analysis of immune cell infiltration indicated a significant decrease in activated dendritic cells in the azoospermia group, with notable correlations between hub genes, particularly SAT1 and HMGCR, and immune cell infiltration. Unique expression patterns of hub genes across various cell types in the human testis were observed, with GPX4 prominently enriched in spermatid/sperm. Eight hub genes exhibited robust diagnostic value (AUC > 0.75). Lastly, a comprehensive hub gene-miRNA-TF-RBP-drug network was constructed.

CONCLUSION

In summary, our investigation unveiled eight FRDEGs associated with azoospermia, which hold potential as biomarkers for the diagnosis and treatment of azoospermia.

Inhibiting neddylation with MLN4924 potentiates hypoxia-induced apoptosis of mouse type B spermatogonia GC-2 cells

Hypoxia, an inadequate supply of tissue oxygen tension, has been reported to induce apoptosis of spermatogenic cells and is associated with male infertility. Neddylation, a post-translational modification similar to ubiquitination, has been shown to be involved in the hypoxia stress response. However, the functions of neddylation in hypoxia-induced apoptosis of spermatogenic cells and its association with male infertility remain largely unexplored. In this study, aiming to explore the role of neddylation in male infertility, we used the specific neddylation inhibitor MLN4924 for treatment in mouse type B spermatogonia GC-2 cells. Our results showed that MLN4924 had no apparent effect on GC-2 cell apoptosis under normoxia, but significantly increased apoptotic cells under hypoxia. Transcriptomic analysis and qPCR assay confirmed that MLN4924 could suppress the expression of hypoxia target genes in GC-2 cells under hypoxia. In addition, MLN4924 could enhance the induction of intracellular and mitochondrial reactive oxygen species (ROS) under hypoxia. These results indicate that the neddylation inhibitor MLN4924 potentiates hypoxia-induced apoptosis of mouse type B spermatogonia GC-2 cells, and neddylation may play an important role in promoting spermatogenic cells to adapt to hypoxia stress.

Thrombotic Alterations under Perinatal Hypoxic Conditions: HIF and Other Hypoxic Markers

Hypoxia is considered to be a stressful physiological condition, which may occur during labor and the later stages of pregnancy as a result of, among other reasons, an aged placenta. Therefore, when gestation or labor is prolonged, low oxygen supply to the tissues may last for minutes, and newborns may present breathing problems and may require resuscitation maneuvers. As a result, poor oxygen supply to tissues and to circulating cells may last for longer periods of time, leading to life-threatening conditions. In contrast to the well-known platelet activation that occurs after reperfusion of the tissues due to an ischemia/reperfusion episode, platelet alterations in response to reduced oxygen exposition following labor have been less frequently investigated. Newborns overcome temporal hypoxic conditions by changing their organ functions or by adaptation of the intracellular molecular pathways. In the present review, we aim to analyze the main platelet modifications that appear at the protein level during hypoxia in order to highlight new platelet markers linked to complications arising from temporal hypoxic conditions during labor. Thus, we demonstrate that hypoxia modifies the expression and activity of hypoxic-response proteins (HRPs), including hypoxia-induced factor (HIF-1), endoplasmic reticulum oxidase 1 (Ero1), and carbonic anhydrase (CIX). Finally, we provide updates on research related to the regulation of platelet function due to HRP activation, as well as the role of HRPs in intracellular Ca2+ homeostasis.

A comprehensive review of natural products with anti-hypoxic activity

Natural products exhibit substantial impacts in the field of anti-hypoxic traetment. Hypoxia can cause altitude sickness and other negative effect on the body. Headache, coma, exhaustion, vomiting and, in severe cases, death are some of the clinical signs. Currently, hypoxia is no longer just a concern in plateau regions; it is also one of the issues that can not be ignored by urban residents. This review covered polysaccharides, alkaloids, saponins, flavonoids, peptides and traditional Chinese compound prescriptions as natural products to protect against hypoxia. The active ingredients, effectiveness and mechanisms were discussed. The related anti-hypoxic mechanisms involve increasing the hemoglobin (HB) content, glycogen content and adenosine triphosphate (ATP) content, removing excessive reactive oxygen species (ROS), reducing lipid peroxidation, regulating the levels of related enzymes in cells, protecting the structural and functional integrity of the mitochondria and regulating the expression of apoptosis-related genes. These comprehensive summaries are beneficial to anti-hypoxic research and provide useful information for the development of anti-hypoxic products.

https://elsevier.proofcentral.com/en-us/landing-page.html?token=baf280639f2773e07701834b1c13daInhibition of spermatogenesis by hypoxia is mediated by V-ATPase via the JNK/c-Jun pathway in mice

Spermatocyte apoptosis is the primary cause of a poor outcome after hypoxia-triggered spermatogenesis reduction (HSR). Vacuolar H⁺-ATPase (V-ATPase) is involved in the regulation of hypoxia-induced spermatocyte apoptosis; however, the underlying mechanism remains to be elucidated. The aim of this study was to investigate the effect of V-ATPase deficiency on spermatocyte apoptosis and the relationship between c-Jun and apoptosis in primary spermatocytes induced by hypoxia. We found that mice under hypoxia exposure for 30 days demonstrated a marked spermatogenesis reduction and downregulation of V-ATPase expression, which were assessed by a TUNEL assay and western blotting, respectively. V-ATPase deficiency resulted in more severe spermatogenesis reduction and spermatocyte apoptosis after hypoxia exposure. We also observed that silencing V-ATPase expression enhanced JNK/c-Jun activation and death receptor-mediated apoptosis in primary spermatocytes. However, inhibition of c-Jun attenuated V-ATPase deficiency-induced spermatocyte apoptosis in primary spermatocytes. In conclusion, the data in this study suggest that V-ATPase deficiency aggravated hypoxia-induced spermatogenesis reduction by promoting spermatocyte apoptosis in mice via the JNK/c-Jun pathway.

A double-edged sword: role of apoptosis repressor with caspase recruitment domain (ARC) in tumorigenesis and ischaemia/reperfusion (I/R) injury

Apoptosis repressor with caspase recruitment domain (ARC) acts as a potent and multifunctional inhibitor of apoptosis, which is mainly expressed in postmitotic cells, including cardiomyocytes. ARC is special for its N-terminal caspase recruitment domain and caspase recruitment domain. Due to the powerful inhibition of apoptosis, ARC is mainly reported to act as a cardioprotective factor during ischaemia‒reperfusion (I/R) injury, preventing cardiomyocytes from being devastated by various catastrophes, including oxidative stress, calcium overload, and mitochondrial dysfunction in the circulatory system. However, recent studies have found that ARC also plays a potential regulatory role in tumorigenesis especially in colorectal cancer and renal cell carcinomas, through multiple apoptosis-associated pathways, which remains to be explored in further studies. Therefore, ARC regulates the body and maintains the balance of physiological activities with its interesting duplex. This review summarizes the current research progress of ARC in the field of tumorigenesis and ischaemia/reperfusion injury, to provide overall research status and new possibilities for researchers.

SIRT3 inhibition suppresses hypoxia-inducible factor 1α signaling and alleviates hypoxia-induced apoptosis of type B spermatogonia GC-2 cells

Hypoxia has been reported to be an important factor leading to male infertility, and it has been reported that hypoxia can induce the apoptosis of mouse spermatogenic cells. Sirtuin 3 (SIRT3) has been reported to promote the degradation of hypoxia-inducible factor 1α (HIF-1α), and thus, we hypothesized that SIRT3 may influence hypoxia-induced apoptosis of spermatogonia. In this study, we overexpressed or inhibited SIRT3 in mouse type B spermatogonia GC-2 cells and then subjected the cells to hypoxia or normoxia, before examining hypoxia-responsive gene expression and cell viability. We report that SIRT3 stabilizes hypoxia-inducible factor 1α (HIF-1α) and activates its downstream target gene expression in GC-2 cells. We also show that the SIRT3 inhibitor 3-TYP suppresses HIF-1α target gene expression and alleviates hypoxia-induced apoptosis of GC-2 cells. Our study reveals the critical role and underlying mechanisms of SIRT3 in hypoxia-induced apoptosis of mouse type B spermatogonia GC-2 cells.

Fluoride Exposure Provokes Mitochondria-Mediated Apoptosis and Increases Mitophagy in Osteocytes via Increasing ROS Production

Fluoride is a persistent environmental pollutant, and its excessive intake causes skeletal and dental fluorosis. However, few studies focused on the effects of fluoride on osteocytes, making up over 95% of all bone cells. This study aimed to investigate the effect of fluoride on osteocytes in vitro, as well as explore the underlying mechanisms. CCK-8, LDH assay, fluorescent probes, flow cytometry, and western blotting were performed to examine cell viability, apoptosis, mitochondria changes, reactive oxygen species (ROS) and mitochondrial ROS (mtROS), and protein expressions. Results showed that sodium fluoride (NaF) exposure (4, 8 mmol/L) for 24 h inhibited the cell viability of osteocytes MLO-Y4 and promoted G0/G1 phase arrest and increased cell apoptosis. NaF treatment remarkably caused mitochondria damage, loss of MMP, ATP decrease, Cyto c release, and Bax/Bcl-2 ratio increase and elevated the activity of caspase-9 and caspase-3. Furthermore, NaF significantly upregulated the expressions of LC-3II, PINK1, and Parkin and increased autophagy flux and the accumulation of acidic vacuoles, while the p62 level was downregulated. In addition, NaF exposure triggered the production of intracellular ROS and mtROS and increased malondialdehyde (MDA); but superoxide dismutase (SOD) activity and glutathione (GSH) content were decreased. The scavenger N-acetyl-L-cysteine (NAC) significantly reversed NaF-induced apoptosis and mitophagy, suggesting that ROS is responsible for the mitochondrial-mediated apoptosis and mitophagy induced by NaF exposure. These findings provide in vitro evidence that apoptosis and mitophagy are cellular mechanisms for the toxic effect of fluoride on osteocytes, thereby suggesting the potential role of osteocytes in skeletal and dental fluorosis.

Overexpression of LncRNA MNX1-AS1/PPFIA4 Activates AKT/HIF-1α Signal Pathway to Promote Stemness of Colorectal Adenocarcinoma Cells

Purpose. The purpose of this study was to explore the role of the lncRNA MNX1-AS1 and its related downstream signaling pathways in colorectal adenocarcinoma (COAD). Methods. COAD tissues and cells were prepared and treated with sh-MNX1-AS1, pcDNA-MNX1-AS1, sh-PPFIA4, LY29004, and their controls. CCK8 and colony formation assays were undertaken for evaluating cell proliferation. Tumor cell migratory ability was detected by transwell assay. Apoptosis detection was processed by YO-PRO-1/PI Staining. The regulated relationship between lncRNA MNX1-AS1 and PPFIA4 was confirmed by RIP-ChIP assay. Q-PCR was applied to detect genes related to tumor cell stemness, proliferation, migration, and apoptosis in each group. Finally, a xenograft tumor model was constructed to verify the result in vivo. Results. COAD patients with high expression of the lncRNA MNX1-AS1 have poor prognosis. LncRNA MNX1-AS1 promotes the stemness of COAD cells. PPFIA4 mediates lncRNA MNX1-AS1 expression and affects COAD cell stemness. LncRNA MNX1-AS1 accelerates proliferation and migration, while it suppresses apoptosis. LncRNA MNX1-AS1/PPFIA4 accelerates tumor growth in COAD model. LncRNA MNX1-AS1/PPFIA4 activates the downstream AKT/HIF-1α signaling pathway to promote COAD development. LY29004 significantly inhibits the tumorigenic ability of lncRNA MNX1-AS1 and PPFIA4. Conclusion. LncRNA MNX1-AS1/PPFIA4 activates AKT/HIF-1α signal pathway to promote the stemness of COAD cells, which could be a new target for COAD treatment.

Hyperuricemia induces liver injury by upregulating HIF-1α and inhibiting arginine biosynthesis pathway in mouse liver and human L02 hepatocytes

The molecular mechanisms of uric acid (UA)-induced liver injury has not been clearly elucidated. In this study, we aimed to investigate the effect and action mechanisms of UA in liver injury. We analyzed the damaging effect of UA on mouse liver and L02 cells and subsequently performed metabolomics studies on L02 cells to identify abnormal metabolic pathways. Finally, we verified transcription factors that regulate related metabolic enzymes. UA directly activated the hepatic NLRP3 inflammasome and Bax apoptosis pathway invivo and invitro. Related metabolites in the arginine biosynthesis pathway (or urea cycle), l-arginine and l-argininosuccinate were decreased, and ammonia was increased in UA-stimulated L02 cells, which was mediated by carbamoyl phosphate synthase 1 (CPS1), argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL) downregulation. UA upregulated hypoxia inducible factor-1alpha (HIF-1α) invivo and invitro, and HIF-1α inhibition alleviated the UA-induced ASS downregulation and hepatocyte injury. In conclusion, UA upregulates HIF-1α and inhibits urea cycle enzymes (UCEs). This leads to liver injury, with evidence of hepatocyte inflammation, apoptosis and oxidative stress.

Effects of NRF-1 and PGC-1α cooperation on HIF-1α and rat cardiomyocyte apoptosis under hypoxia

BACKGROUND

Hypoxia is a primary inducer of cardiomyocyte injury, its significant marker being hypoxia-induced cardiomyocyte apoptosis. Nuclear respiratory factor-1 (NRF-1) and hypoxia-inducible factor-1α (HIF-1α) are transcriptional regulatory elements implicated in multiple biological functions, including oxidative stress response. However, their roles in hypoxia-induced cardiomyocyte apoptosis remain unknown. The effect HIF-1α, together with NRF-1, exerts on cardiomyocyte apoptosis also remains unclear.

METHODS

We established a myocardial hypoxia model and investigated the effects of these proteins on the proliferation and apoptosis of rat cardiomyocytes (H9C2) under hypoxia. Further, we examined the association between NRF-1 and HIF-1α to improve the current understanding of NRF-1 anti-apoptotic mechanisms.

RESULTS

The results show that NRF-1 and HIF-1α are important anti-apoptotic molecules in H9C2 cells under hypoxia, although their regulatory mechanisms differ. NRF-1 could bind to the promoter region of Hif1a and negatively regulate its expression. Additionally, HIF-1β exhibited competitive binding with NRF-1 and HIF-1α, demonstrating a synergism between NRF-1 and the peroxisome proliferator-activated receptor-gamma coactivator-1α.

CONCLUSION

These results indicate that cardiomyocytes can regulate different molecular patterns to tolerate hypoxia, providing a novel methodological framework for studying cardiomyocyte apoptosis under hypoxia.

Response to Different Oxygen Partial Pressures and Evolution Analysis of Apoptosis-Related Genes in Plateau Zokor (Myospalax baileyi)

The plateau zokor (Myospalax baileyi) is a native species of the Qinghai–Tibet Plateau that spends its entire life underground in sealed burrows with hypoxic conditions. The present study aimed to assess the sequence characteristics of apoptosis-related genes and the response to different oxygen partial pressures (pO₂) in plateau zokor and Sprague-Dawley rats. The sequences of the p53-induced protein with a death domain (Pidd), p53-upregulated modulator of apoptosis (Puma), insulin-like growth factor binding protein 3 (Igfbp3), and apoptosis protease-activating factor 1 (Apaf1) were evaluated concerning homology and convergent evolution sites, and their mRNA levels were evaluated in different tissues under 14.13 (3,300 m) and 16.12 kPa (2,260 m) pO₂ conditions. Our results showed that, (1) the sequences of the apoptosis-related genes in plateau zokor were highly similar to those of Nannospalax galili, followed by Rattus norvegicus; (2). Pidd, Puma, Igfbp3, and Apaf1 of plateau zokor were found to have five, one, two, and five convergent sites in functional domains with N. galili, respectively. Lastly (3), under low pO₂, the expression of Pidd and Puma was downregulated in the lung of plateau zokors. In turn, Igfbp3 and Apaf1 were upregulated in the liver and lung, and Puma was upregulated in the skeletal muscle of plateau zokor under low pO₂. In Sprague-Dawley rats, low pO₂ downregulated Puma and Apaf1 expression in the liver and downregulated Igfbp3 and Puma in the lung and skeletal muscle separately. In contrast, low pO₂ upregulated Pidd expression in the liver and skeletal muscle of Sprague-Dawley rats. Overall, the expression patterns of Apaf1, Igfbp3, and Puma showed the opposite pattern in the liver, lung, and skeletal muscle, respectively, of plateau zokor as compared with Sprague-Dawley rats. In conclusion, for the long-time adaptation to hypoxic environments, Pidd, Puma, Igfbp3, and Apaf1 of plateau zokor underwent convergent evolution, which we believe may have led to upregulation of their levels under low oxygen partial pressures to induce apoptosis, so as to suppress tumorigenesis under hypoxic environments in plateau zokor.

Alterations of RNA Modification in Mouse Germ Cell-2 Spermatids Under Hypoxic Stress

Hypoxia is a known stress factor in mammals and has been shown to potentially impair male fertility, which manifests as spermatogenic dysfunction and decreased semen quality. Studies have shown that RNA modifications, the novel post-transcriptional regulators, are involved in spermatogenesis, and hypoxia-induced alterations in RNA modification in testes and sperm cells may be associated with impaired spermatogenesis in mice. However, the molecular mechanisms via which RNA modifications influence spermatogenesis under hypoxic stress conditions are unclear. In this study, we generated a mouse Germ Cell-2 spermatid (GC-2spd) hypoxia model by culturing cells in a 1% O2 incubator for 48 h or treating them with CoCl2 for 24 h. The hypoxia treatment significantly inhibited proliferation and induced apoptosis in GC-2spd cells. The RNA modification signatures of total RNAs (2 types) and differentially sized RNA fragments (7 types of approximately 80 nt-sized tRNAs; 9 types of 17–50 nt-sized sncRNAs) were altered, and tRNA stability was partially affected. Moreover, the expression profiles of sncRNAs, such as microRNAs, tsRNAs, rsRNAs, and ysRNAs, were significantly regulated, and this might be related to the alterations in RNA modification and subsequent transcriptomic changes. We comprehensively analyzed alterations in RNA modification signatures in total RNAs, tRNAs (approximately 80 nt), and small RNAs (17–50 nt) as well as the expression profiles of sncRNAs and transcriptomes in hypoxia-treated GC-2spd cells; our data suggested that RNA modifications may be involved in cellular responses under hypoxic stress conditions and could provide a basis for a better understanding of the molecular mechanisms underlying male infertility.

Effective Parts of Gentiana straminea Maxim Attenuates Hypoxia-Induced Oxidative Stress and Apoptosis

Hypoxia occurs in physiological situations and several pathological situations, inducing oxidative stress. G straminea Maxim (G.s Maxim) is a traditional Tibetan medicine that exerts several biological effects. This study focused on the protective effects of G.s Maxim in hypoxia-induced oxidative stress and apoptosis. We found that G.s Maxim significantly increased survival and reduced oxidative stress in hypoxic mice. Various extraction parts of G.s Maxim showed antioxidant activity and significantly improved survival in hypoxia-injured PC12 cells. G.s Maxim reduced hypoxia-induced cell apoptosis and leakage of lactate dehydrogenase. Hypoxic cells had increased malondialdehyde levels but reduced superoxide dismutase activity and G.s Maxim reversed these effects. Moreover, G.s Maxim suppressed hypoxia-induced apoptosis by inducing protein expression of B cell leukemia/lymphoma-2 and reducing the expression of hypoxia-inducible factor-1α, Bcl-2-associated X, and nuclear factor-k-gene binding. These findings suggest that G.s Maxim attenuates hypoxia-induced injury associated with oxidative stress and apoptosis.

Effects of Environmental and Pathological Hypoxia on Male Fertility

Male infertility is a widespread health problem affecting approximately 6%-8% of the male population, and hypoxia may be a causative factor. In mammals, two types of hypoxia are known, including environmental and pathological hypoxia. Studies looking at the effects of hypoxia on male infertility have linked both types of hypoxia to poor sperm quality and pregnancy outcomes. Hypoxia damages testicular seminiferous tubule directly, leading to the disorder of seminiferous epithelium and shedding of spermatogenic cells. Hypoxia can also disrupt the balance between oxidative phosphorylation and glycolysis of spermatogenic cells, resulting in impaired self-renewal and differentiation of spermatogonia, and failure of meiosis. In addition, hypoxia disrupts the secretion of reproductive hormones, causing spermatogenic arrest and erectile dysfunction. The possible mechanisms involved in hypoxia on male reproductive toxicity mainly include excessive ROS mediated oxidative stress, HIF-1α mediated germ cell apoptosis and proliferation inhibition, systematic inflammation and epigenetic changes. In this review, we discuss the correlations between hypoxia and male infertility based on epidemiological, clinical and animal studies and enumerate the hypoxic factors causing male infertility in detail. Demonstration of the causal association between hypoxia and male infertility will provide more options for the treatment of male infertility.

Effects of acute hypoxia and reoxygenation on oxygen sensors, respiratory metabolism, oxidative stress, and apoptosis in hybrid yellow catfish "Huangyou-1"

The regulation mechanism of the hybrid yellow catfish "Huangyou-1" was assessed under conditions of hypoxia and reoxygenation by examination of oxygen sensors and by monitoring respiratory metabolism, oxidative stress, and apoptosis. The expressions of genes related to oxygen sensors (HIF-1α, HIF-2α, VHL, HIF-1β, PHD2, and FIH-1) were upregulated in the brain and liver during hypoxia, and recovered compared with control upon reoxygenation. The expressions of genes related to glycolysis (HK1, PGK1, PGAM2, PFK, and LDH) were increased during hypoxia and then recovered compared with control upon reoxygenation. The mRNA levels of CS did not change during hypoxia in the brain and liver, but increased during reoxygenation. The mRNA levels of SDH decreased significantly only in the liver during hypoxia, but later increased compared with control upon reoxygenation in both tissues. Under hypoxic conditions, the expressions of genes related to oxidative stress (SOD1, SOD2, GSH-Px, and CAT) and the activity of antioxidant enzymes (SOD, CAT, and GSH-Px) and MDA were upregulated compared with control. The expressions of genes related to apoptosis (Apaf-1, Bax, Caspase 3, Caspase 9, and p53) were higher than those in control during hypoxic exposure, while the expressions of Bcl-2 and Cyt C were decreased. The findings of the transcriptional analyses will provide insights into the molecular mechanisms of hybrid yellow catfish "Huangyou-1" under conditions of hypoxia and reoxygenation. Overall, these findings showed that oxygen sensors of "Huangyou-1" are potentially useful biomarkers of environmental hypoxic exposure. Together with genes related to respiratory metabolism, oxidative stress and apoptosis occupy a quite high position in enhancing hypoxia tolerance. Our findings provided new insights into the molecular regulatory mechanism of hypoxia in "Huangyou-1."

Effects of chronic intermittent hypobaric hypoxia on prostate-specific antigen (PSA) in Chilean miners

OBJECTIVE

The aim was to determine the effects of chronic intermittent hypobaric hypoxia (CIHH) on prostate-specific antigen (PSA) levels in Chilean miners who work at different altitudes.

METHODS

A cross-sectional study was conducted between April and July 2019. Miners from five mines (N=338) at different altitudes were evaluated. We recorded sociodemographic, working and altitude information. Haemoglobin oxygen saturation (SaO2) and haemoglobin (Hb) were measured in situ, while PSA and testosterone were analysed at a low level. Linear mixed-effect models were used to evaluate the association between PSA level and two CIHH exposures: composite CIHH (with four descriptors) and ChileStd-CIHH (CIHH Chilean standard; based on the Chilean technical guide for occupational exposure to CIHH). All models were adjusted by age, body mass index and day of the work the samples were taken.

RESULTS

Highest and lowest PSA levels were found in mines ≥3000 m above sea level (mine 3: median=0.75, IQR=-0.45; mine 4: median=0.46, IQR=-0.35). In the multilevel models, the wider altitude difference between mining operation and camp showed lower PSA levels (model D: βPSA=-0.93 ng/mL, βlogPSA=-0.07, p<0001), adjusted for other CIHH descriptors, SaO2, Hb and testosterone. The descriptors of composite CIHH explained better PSA variations than ChileStd-CIHH (model D: marginal R2=0.090 vs model A: marginal R2=0.016).

CONCLUSIONS

Occupational health regulations and high altitude medicine should consider these results as initial evidence on the inclusion of new descriptors for CIHH and the possible effect of this exposure on PSA levels in this male-dominated occupational sector.

Hypoxia-induced alteration of RNA modifications in the mouse testis and sperm

Hypobaric hypoxia as an extreme environment in a plateau may have deleterious effects on human health. Studies have indicated that rush entry into a plateau may reduce male fertility and manifest in decreased sperm counts and weakened sperm motility. RNA modifications are sensitive to environmental changes and have recently emerged as novel post-transcriptional regulators in male spermatogenesis and intergenerational epigenetic inheritance. In the present study, we generated a mouse hypoxia model simulating the environment of 5500 meters in altitude for 35 days, which led to compromised spermatogenesis, decreased sperm counts, and an increased sperm deformation rate. Using this hypoxia model, we further applied our recently developed high-throughput RNA modification quantification platform based on LC-MS/MS, which exhibited the capacity to simultaneously examine 25 types of RNA modifications. Our results revealed an altered sperm RNA modifications signature in the testis (6 types) and mature sperm (11 types) under the hypoxia model, with 4 types showing overlap (Am, Gm, m7G, and m22G). Our data first drew the signature of RNA modification profiles and comprehensively analyzed the alteration of RNA modification levels in mouse testis and sperm under a mouse hypoxia model. These data may be highly related to human conditions under a similar hypoxia environment.

Apoptosis detection: a purpose-dependent approach selection

Apoptosis is closely associated with many diseases. Detection of apoptosis can be achieved by morphology, biochemistry, molecular biology, immunology, and other techniques. However, as technologies are increasingly used for the detection of apoptosis, many researchers are confused about how to choose a suitable method to detect apoptosis. Selection of a suitable detection method for apoptosis will help clinical diagnosis and prevention of diseases. This article reviews the selection of optimal apoptosis-detection methods based on research purposes and technique principles.

Mitochondrial remodelling-a vicious cycle in diabetic complications

Diabetes mellitus (DM) is a chronic, metabolic condition characterized by excessive blood glucose that causes perturbations in physiological functioning of almost all the organs of human body. This devastating metabolic disease has its implications in cognitive decline, heart damage, renal, retinal and neuronal complications that severely affects quality of life and associated with decreased life expectancy. Mitochondria possess adaptive mechanisms to meet the cellular energy demand and combat cellular stress. In recent years mitochondrial homeostasis has been point of focus where several mechanisms regulating mitochondrial health and function are evaluated. Mitochondrial dynamics plays crucial role in maintaining healthy mitochondria in cell under physiological as well as stress condition. Mitochondrial dynamics and corresponding regulating mechanisms have been implicated in progression of metabolic disorders including diabetes and its complications. In current review we have discussed about role of mitochondrial dynamics under physiological and pathological conditions. Also, modulation of mitochondrial fission and fusion in diabetic complications are described. The available literature supports mitochondrial remodelling as reliable target for diabetic complications.

microRNA-186 alleviates oxygen-glucose deprivation/reoxygenation-induced injury by directly targeting hypoxia-inducible factor-1α

Previous studies have suggested that microRNA-186 (miR-186) can be induced under hypoxic conditions, and is associated with apoptosis. This study was undertaken to explore the exact role of this microRNA (miRNA) in the apoptotic death of neurons during cerebral ischemic/reperfusion (I/R) injury. To model cerebral ischemia/reperfusion (I/R) injuries, we utilized a transient middle cerebral artery occlusion approach in rats, as well as a model of oxygen-glucose deprivation/reoxygenation (OGD/R) in Neuro2a cells. We found that in both in vitro and in vivo models of cerebral I/R injuries, levels of miR-186 were markedly decreased. When we overexpressed miR-186, this was associated with a reduction in the apoptotic death of neuroblastoma cells in the OGD/R model system, whereas the opposite was true when this miRNA was instead inhibited. We further found miR-186 to directly target hypoxia-inducible factor 1α (HIF-1α) by interacting with the 3'-untranslated region of this mRNA. When we knocked down HIF-1α, this partially overcame the apoptotic death of cells in response to OGD/R injury and associated miR-186 downregulation. Our findings indicate that miR-186 is able to reduce ischemic injury to neurons at least in part through downregulating HIF-1α, suggesting that the miR-186/HIF-1α axis is a potential therapeutic target for the treatment of ischemic stroke.

Norwogonin attenuates hypoxia-induced oxidative stress and apoptosis in PC12 cells

Background

Norwogonin is a natural flavone with three phenolic hydroxyl groups in skeletal structure and has excellent antioxidant activity. However, the neuroprotective effect of norwogonin remains unclear. Here, we investigated the protective capacity of norwogonin against oxidative damage elicited by hypoxia in PC12 cells.

Methods

The cell viability and apoptosis were examined by MTT assay and Annexin V-FITC/PI staining, respectively. Reactive oxygen species (ROS) content was measured using DCFH-DA assay. Lactate dehydrogenase (LDH), malondialdehyde (MDA) and antioxidant enzyme levels were determined using commercial kits. The expression of related genes and proteins was measured by real-time quantitative PCR and Western blotting, respectively.

Results

We found that norwogonin alleviated hypoxia-induced injury in PC12 cells by increasing the cell viability, reducing LDH release, and ameliorating the changes of cell morphology. Norwogonin also acted as an antioxidant by scavenging ROS, reducing MDA production, maintaining the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and decreasing the expression levels of HIF-1α and VEGF. In addition, norwogonin prevented cell apoptosis via inhibiting the expression levels of caspase-3, cytochrome c and Bax, while increasing the expression levels of Bcl-2 and the ratio of Bcl-2/Bax.

Conclusions

Norwogonin attenuates hypoxia-induced injury in PC12 cells by quenching ROS, maintaining the activities of antioxidant enzymes, and inhibiting mitochondrial apoptosis pathway.

hCINAP serves a critical role in hypoxia‑induced cardiomyocyte apoptosis via modulating lactate production and mitochondrial‑mediated apoptosis signaling

Acute myocardial infarction (AMI) is a major cause of heart failure and is associated with insufficient myocardial oxygen supply. However, the molecular mechanisms underlying hypoxia‑induced cardiomyocyte apoptosis are not completely understood. In the present study, the role of human coilin interacting nuclear ATPase protein (hCINAP) in cardiomyocytes was investigated. AC16 cells were divided into the following four groups: i) Small interfering (si)RNA‑control (Ctrl); (ii) siRNA‑hCINAP; (iii) empty vector; and (iv) hCINAP‑Flag. Protein expression was assessed using western blotting. MTT and apoptosis assays were conducted to detect cell viability and apoptosis, respectively. CCK8 assays and apoptosis assays were used to detect cell viability and apoptosis, respectively. hCINAP promoter activity was examined by luciferase reporter assay. hCINAP expression was induced in a hypoxia‑inducible factor‑1α‑dependent manner under hypoxic conditions. Compared with the siRNA‑Ctrl group, hCINAP knockdown inhibited apoptosis, whereas compared with the vector group, hCINAP overexpression increased apoptosis under hypoxic conditions. Mechanistically, compared with the siRNA‑Ctrl group, hCINAP knockdown decreased hypoxia‑induced lactate accumulation via regulating lactate dehydrogenase A activity. Moreover, the results indicated that hCINAP was associated with mitochondrial‑mediated apoptosis via Caspase signaling. Collectively, the present study suggested that hCINAP was an important regulator in hypoxia‑induced apoptosis and may serve as a promising therapeutic target for AMI.

N6-(2-hydroxyethyl)-Adenosine Induces Apoptosis via ER Stress and Autophagy of Gastric Carcinoma Cells In Vitro and In Vivo

Gastric cancer is the most common malignant tumor of the digestive tract and is great challenge in clinical treatment. N6-(2-Hydroxyethyl)-adenosine (HEA), widely present in various fungi, is a natural adenosine derivative with many biological and pharmacological activities. Here, we assessed the antineoplastic effect of HEA on gastric carcinoma. HEA exerted cytotoxic effects against gastric carcinoma cells (SGC-7901 and AGS) in a dose and time-dependent manner. Additionally, we found that HEA induced reactive oxygen species production and mitochondrial membrane potential depolarization. Moreover, it could trigger caspase-dependent apoptosis, promoting intracellular Ca²⁺-related endoplasmic reticulum (ER) stress and autophagy. On the other hand, HEA could significantly inhibit the growth of transplanted tumors in nude mice and induce apoptosis of tumor tissues cells in vivo. In conclusion, HEA induced apoptosis of gastric carcinoma cells in vitro and in vivo, demonstrating that HEA is a potential chemotherapeutic agent for gastric carcinoma.

HIF-1α induces hypoxic apoptosis of MLO-Y4 osteocytes via JNK/caspase-3 pathway and the apoptotic-osteocyte-mediated osteoclastogenesis in vitro

Apoptotic osteocytes were found in the hypoxic bone microenvironment in osteoporosis, osteotomy, orthodontic tooth movement and periodontitis, and played a key role in bone remolding and the differentiation of osteoclasts. Hypoxia inducible factor-1α(HIF-1α), as a transcription factor under hypoxic conditions, has been confirmed to participate in cell apoptosis. However, the effect of HIF-1α on osteocytes apoptosis and the osteocyte-mediated osteoclast formation remains elusive. Here, we hypothesized that HIF-1α was involved in osteocytes apoptosis. Our results showed that CoCl₂ increased the MLO-Y4 cells apoptosis by upregulating the proapoptotic gene expression of caspase-3. Moreover, siRNA-mediated knockdown of HIF-1α decreased the phosphorylation by JNK and the activation of caspase-3 to inhibit the cell apoptosis in MLO-Y4. Furthermore, SP600125, an inhibitor of JNK, reversed CoCl₂-induced the increased apoptosis of MLO-Y4 cells in term of reducing the expression of caspase-3. These findings revealed that HIF-1α served as a pro-apoptotic factor in the apoptosis of MLO-Y4 cells cultured with CoCl₂, by activating the JNK/caspase-3 signaling pathway. Besides, the osteocyte-mediated osteoclastogenesis was reduced with the decline of the expression of HIF-1α and caspase-3 in MLO-Y4 cells. Our study provided an idea for a more comprehensive understanding of HIF-1α and the process of bone remodeling.

Long non-coding RNAs towards precision medicine in gastric cancer: early diagnosis, treatment, and drug resistance

Gastric cancer is a deadly disease and remains the third leading cause of cancer-related death worldwide. The 5-year overall survival rate of patients with early-stage localized gastric cancer is more than 60%, whereas that of patients with distant metastasis is less than 5%. Surgical resection is the best option for early-stage gastric cancer, while chemotherapy is mainly used in the middle and advanced stages of this disease, despite the frequently reported treatment failure due to chemotherapy resistance. Therefore, there is an unmet medical need for identifying new biomarkers for the early diagnosis and proper management of patients, to achieve the best response to treatment. Long non-coding RNAs (lncRNAs) in body fluids have attracted widespread attention as biomarkers for early screening, diagnosis, treatment, prognosis, and responses to drugs due to the high specificity and sensitivity. In the present review, we focus on the clinical potential of lncRNAs as biomarkers in liquid biopsies in the diagnosis and prognosis of gastric cancer. We also comprehensively discuss the roles of lncRNAs and their molecular mechanisms in gastric cancer chemoresistance as well as their potential as therapeutic targets for gastric cancer precision medicine.

Hypoxia‑induced miR‑210 contributes to apoptosis of mouse spermatocyte GC‑2 cells by targeting Kruppel‑like factor 7

The aim of the present study was to investigate the underlying mechanisms of hypoxia-induced microRNA (miR)-210 effects on mouse GC-2spd (GC-2) cells. GC-2 cells were subjected to hypoxia or normoxia for 12, 24, 48 and 72 h. Apoptosis of GC-2 cells was detected using terminal deoxynucleotidyl-transferase-meditated dUTP nick end labeling and flow cytometry. Reverse transcription-quantitative polymerase chain reaction was performed to analyze the expression of miR-210. Hypoxia-inducible factor-1α (HIF-1α), caspase-3, B-cell lymphoma 2, apoptosis regulator BAX and Kruppel-like factor 7 (KLF7) protein expression levels were detected by western blotting. Luciferase reporter gene assays were used to assess the targeting effects of miR-210 on KLF7. Hypoxia induced GC-2 cell apoptosis and increased the expression of HIF-1α and pro-apoptotic proteins; however, decreased anti-apoptotic protein expression levels. Furthermore, hypoxia resulted in the upregulation of miR-210 in GC-2 cells. HIF-1α and miR-210 were involved in the apoptosis of GC-2 cells by mediating the expression of apoptosis-associated proteins. Furthermore, KLF7 was directly targeted by miR-210 to influence the apoptosis of GC-2 cells subjected to hypoxia. The results suggested that hypoxia-induced miR-210 stimulated the activation of the apoptosis signaling pathway and contributed to the apoptosis of GC-2 cells by targeting KLF7.

Hypermucoviscous Klebsiella pneumoniae infections induce platelet aggregation and apoptosis and inhibit maturation of megakaryocytes

INTRODUCTION

Different Klebsiella pneumoniae strains carry different virulence factors and antibiotic resistance and may cause thrombocytopenia. This study aimed to investigate the effects of different infections caused by K. pneumoniae on platelets.

METHODS

Two hypermucoviscous K. pneumoniae strains and two classic strains were collected from clinical blood culture, and in both groups, there was a carbapenem-resistant strain and a carbapenem-sensitive strain. Mouse infection models were constructed by intraperitoneally injecting different strains, and mice injected with phosphate-buffered saline served as a control. Count, aggregation rate and apoptosis proportion of platelets within 12 h were examined. CD41 expression was measured in bone marrow cells to determine the maturation of megakaryocytes. The concentrations of lipopolysaccharides and related signaling molecules were also measured.

RESULTS

The platelet aggregation rate was much significantly higher in the two hypermucoviscous groups, while it showed no difference in the classic groups compared to the control group. All infections induced apoptosis of platelets, among which the highest apoptosis proportions were observed in infections caused by the hypermucoviscous carbapenem-sensitive strain. In both hypermucoviscous groups the CD41 mean fluorescence intensity was much lower than that in the control group, indicating that the maturation of megakaryocytes in the hypermucoviscous groups was significantly inhibited. Lipopolysaccharides were significantly higher and TLR4/Myd88 and JNK/MAPK pathways were strongly activated in hypermucoviscous groups.

CONCLUSIONS

The results indicate that hypermucoviscous K. pneumoniae can reduce platelet count by several pathways. Although antibiotic resistance is rapidly emerging worldwide, it has little influence on the decrease in platelets.

Protective effect of ghrelin on testicular damages caused by chronic hypoxia in rats: A histopathological study

Hypoxia can lead to changes in the blood flow, nutrition and oxygenation of male germ cells and results in fertility reduction through the increase in oxidative stress. This study aims to evaluate the effect of ghrelin on testicular damage induced by hypoxia in rats. In this experimental study, 24 male rats were randomly divided into four groups: control, hypoxia, hypoxia + ghrelin and ghrelin. Animals in the control and ghrelin groups were kept in room air with 21% oxygen. The animals in the groups of hypoxia and hypoxia + ghrelin were subjected to 11% oxygen for 14 consecutive days in the hypoxia chamber. At the end of the study, the testes were removed and histological changes, as well as the apoptotic index, were investigated. Morphometrical analysis showed that hypoxia caused a significant decrease in the seminiferous tubules diameter, the germinal epithelium thickness and main Johnson's score compared to the control group (p < .05). In addition, statistical comparisons revealed a significant increase in the apoptotic index in the hypoxia group (p < .05). Administration of ghrelin + hypoxia improved the parameters mentioned above (p < .05). The results of this study indicated that ghrelin decreases the testicular damages caused by hypoxia in the rats by antioxidative activity.

Nrdp1 Increases Ischemia Induced Primary Rat Cerebral Cortical Neurons and Pheochromocytoma Cells Apoptosis Via Downregulation of HIF-1α Protein

Neuregulin receptor degradation protein-1 (Nrdp1) is an E3 ubiquitin ligase that targets proteins for degradation and regulates cell growth, apoptosis and oxidative stress in various cell types. We have previously shown that Nrdp1 is implicated in ischemic cardiomyocyte death. In this study, we investigated the change of Nrdp1 expression in ischemic neurons and its role in ischemic neuronal injury. Primary rat cerebral cortical neurons and pheochromocytoma (PC12) cells were infected with adenoviral constructs expressing Nrdp1 gene or its siRNA before exposing to oxygen-glucose deprivation (OGD) treatment. Our data showed that Nrdp1 was upregulated in ischemic brain tissue 3 h after middle cerebral artery occlusion (MCAO) and in OGD-treated neurons. Of note, Nrdp1 overexpression by Ad-Nrdp1 enhanced OGD-induced neuron apoptosis, while knockdown of Nrdp1 with siRNA attenuated this effect, implicating a role of Nrdp1 in ischemic neuron injury. Moreover, Nrdp1 upregulation is accompanied by increased protein ubiquitylation and decreased protein levels of ubiquitin-specific protease 8 (USP8) in OGD-treated neurons, which led to a suppressed interaction between USP8 and HIF-1α and subsequently a reduction in HIF-1α protein accumulation in neurons under OGD conditions. In conclusion, our data support an important role of Nrdp1 upregulation in ischemic neuronal death, and suppressing the interaction between USP8 and HIF-1α and consequently the hypoxic adaptive response of neurons may account for this detrimental effect.