The evolutionarily conserved hif-1/bnip3 pathway promotes mitophagy and mitochondrial fission in crustacean testes during hypoxia

Hypoxia induces ferroptotic cell death mediated by activation of the inner mitochondrial membrane fission protein MTP18/Drp1 in invertebrates

Hypoxia and ischemia damage sensitive organelles such as mitochondria, and mitochondrial dysfunction contributes to metabolic disorders in crustaceans under hypoxia. The mechanisms associated with ferroptosis in hypoxic disorders have not been determined in crustaceans. In particular, the early molecular events of mitochondrial dynamics in crustaceans require clarification. In this study, two evolutionarily conserved mitochondrial fission proteins, Drp1 and MTP18, were identified in oriental river prawn (Macrobrachium nipponense). In vitro, ferroptosis-mediated impairment of mitochondrial membrane potential was induced by hypoxia in oriental river prawn hemocytes. In hypoxia-induced hemocytes, activation of Drp1 by increased phosphorylation at S616 was identified. Drp1 mitochondrial translocation also increased, and mitochondrial fusion-related protein expression decreased in vivo. Altered mitochondrial fission-fusion dynamics have been linked to mitochondrial dysfunction, inducing a classic ferroptosis mechanism. Marf overexpression or Drp1 knockdown protected against mitochondrial dysfunction and ferroptotic cell death in vitro. Furthermore, hypoxia-induced mitochondrial fission was verified to be driven by Drp1/MTP18 interaction. Under hypoxia, MTP18 transcription was increased by the binding of activated HIF-1α to hypoxia response elements in its promoter. Conjointly, MTP18 knockdown resulted in less apoptosis and decreased prawn mortality in gill tissue in vitro, suggesting that adaptation to hypoxia involves a vital function by MTP18. In conclusion, we uncovered a conserved role of mitochondrial fission in hypoxia-induced ferroptotic cell death. Therefore, we suggest that specific modulation of MTP18/DRP1-mediated mitochondrial dynamics might be a potential therapeutic strategy in hypoxic stress-induced tissue injury in invertebrates.

Hypoxia-Inducible Factor-1α Regulates BNIP3-Dependent Mitophagy and Mediates Metabolic Reprogramming Through Histone Lysine Lactylation Modification to Affect Glioma Proliferation and Invasion

OBJECTIVE

Gliomas are the predominant form of malignant brain tumors. We investigated the mechanism of hypoxia-inducible factor-1α (HIF-1α) affecting glioma metabolic reprogramming, proliferation and invasion.

METHODS

Human glioma cell U87 was cultured under hypoxia and treated with small interfering (si)HIF-1α, si-B cell lymphoma-2/adenovirus E1B 19-kDa interacting protein 3 (siBNIP3), si-YT521-B homology domain 2 (siYTHDF2), 3-methyladenine and 2-deoxyglucose, with exogenous sodium lactate-treated normally-cultured cells as a lactate-positive control. Cellular hexokinase 2, lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 enzyme activities, glucose uptake, and levels of lactic acid and adenosine triphosphate (ATP), and HIF-1α, glycolysis-related proteins, mitophagy-related proteins, histone H3 lysine 18 lactylation (H3K18la) and YTHDF2 were determined by ELISA, 2-NBDG, kits, and Western blot. Extracellular acidification rate (ECAR), and cell proliferation, invasion, apoptosis and mitophagy were evaluated by extracellular flux analysis, CCK-8, Transwell, flow cytometry, and immunofluorescence staining. H3K18la-YTHDF2 relationship and YTHDF2-BNIP3 interaction were assessed by ChIP and Co-IP assays.

RESULTS

Hypoxia-induced highly-expressed HIF-1α in glioma cells increased glycolysis-related protein levels, glycolytic enzyme activities, glucose uptake, lactic acid production, ATP level and ECAR, thereby promoting metabolic reprogramming, invasion and proliferation. HIF-1α mediated metabolic reprogramming, proliferation and invasion through BNIP3-dependent mitophagy, which were partly negated by mitophagy inhibition. HIF-1α induced histone Kla modification to upregulate YTHDF2. YTHDF2 downregulation impeded YTHDF2-BNIP3 interaction and inhibited HIF-1α-induced BNIP3-dependent mitophagy, curbing glioma cell metabolic reprogramming, proliferation and invasion.

CONCLUSIONS

Hypoxia-induced high HIF-1α expression upregulated YTHDF2 through hH3K18la modification, enhanced YTHDF2-BNIP3 interaction, and regulated BNIP3-dependent mitophagy-mediated metabolic reprogramming to affect glioma proliferation and invasion.

Effects of Cryptorchidism on the Semen Quality of Giant Pandas from the Perspective of Seminal Plasma Proteomics

Giant pandas are an endangered species with low reproductive rates. Cryptorchidism, which can negatively affect reproduction, is also often found in pandas. Seminal plasma plays a crucial role in sperm-environment interactions, and its properties are closely linked to conception potential in both natural and assisted reproduction. The research sought to identify seminal fluid protein content variations between normal and cryptorchid giant pandas. Methods: Using a label-free MS-based method, the semen proteomes of one panda with cryptorchidism and three normal pandas were studied, and the identified proteins were compared and functionally analyzed. Results: Mass spectrometry identified 2059 seminal plasma proteins, with 361 differentially expressed proteins (DEPs). Gene ontology (GO) analysis revealed that these DEPs are mainly involved in the phosphate-containing compound metabolic, hydrolase activity, and kinase activity areas (p ≤ 0.05). The KEGG functional enrichment analysis revealed that the top 20 pathways were notably concentrated in the adipocyte lipolysis and insulin metabolism pathway, with a significance level of p ≤ 0.05. Further analysis through a protein-protein interaction (PPI) network identified nine key proteins that may play crucial roles, including D2GXH8 (hexokinase Fragment), D2HSQ6 (protein tyrosine phosphatase), and G1LHZ6 (Calmodulin 2). Conclusions: We suspect that the high abundance of D2HSQ6 in cryptorchid individuals is associated with metabolic pathways, especially the insulin signal pathway, as a typical proteomic feature related to its pathological features. These findings offer insight into the ex situ breeding conditions of this threatened species.

Can the male germline offer insight into mammalian brain size expansion?

Recent advances in single-cell transcriptomic data have greatly expanded our understanding of both spermatogenesis and the molecular mechanisms of male infertility. However, this growing wealth of data could also shed light on a seemingly unrelated biological problem: the genetic basis of mammalian brain size expansion throughout evolution. It is now increasingly recognized that the testis and brain share many cellular and molecular similarities including pivotal roles for the RAS/MAPK and PI3K/AKT/mTOR pathways, mutations in which are known to have a pronounced impact on cell proliferation. Most notably, in the stem cell lineages of both organs, new mutations have been shown to increase cellular output over time. These include 'selfish' mutations in spermatogonial stem cells, which disproportionately increase the proportion of mutant sperm, and-to draw a parallel-human-specific mutations in neural stem cells which, by increasing the number of neurons, have been implicated in neocortical expansion. Here we speculate that the origin for many 'expansion'-associated mutations is the male germline and that as such, a deeper understanding of the mechanisms controlling testicular turnover may yield fresh insight into the biology and evolution of the brain.

UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism

Aquatic environments are subject to ultraviolet B (UVB) radiation incidence, and its effects on organisms are dose-dependent. Besides DNA, mitochondria are an important target of this radiation that causes structural damage and impairs its functional dynamics. Here, we hypothesize that mitophagy acts as an organelle quality control mechanism to mitigate UVB impacts in embryonic cells. Then, freshwater prawn Macrobrachium olfersii embryos was used as a model to investigate the effects of UVB on genes (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) and proteins (TOM20, PINK1, p62 and LC3B) involved in mitophagy modulation. The choice of genes and proteins was based on the identification of mitochondrial membrane (Tomm20, Opa1 and TOM20), mediation of mitophagy (Pink1, Prkn and PINK1), and recognition of mitochondria by the autophagosome membrane (Sqstm1, Map1lc3, p62 and LC3B). First, the phylogeny of all genes presented bootstrap values >80 and conserved domains among crustacean species. Gene expression was inherently modulated during development, with transcripts (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) overexpressed in the initial and final stages of development. Moreover, UVB radiation induced upregulation of Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3 genes at 6 h after exposure. Interestingly, after 12 h, the protein content of PINK1, p62, and LC3B increased, while TOM20 was not responsive. Despite UVB radiation's harmful effects on embryonic cells, the chronology of gene expression and protein content indicates rapid activation of mitophagy, serving as an organelle quality control mechanism, given the analyzed cells' integrity.

Did mitophagy follow the origin of mitochondria?

Mitophagy is the process of selective autophagy that removes superfluous and dysfunctional mitochondria. Mitophagy was first characterized in mammalian cells and is now recognized to follow several pathways including basal forms in specific organs. Mitophagy pathways are regulated by multiple, often interconnected factors. The present review aims to streamline this complexity and evaluate common elements that may define the evolutionary origin of mitophagy. Key issues surrounding mitophagy signaling at the mitochondrial surface may fundamentally derive from mitochondrial membrane dynamics. Elements of such membrane dynamics likely originated during the endosymbiosis of the alphaproteobacterial ancestor of our mitochondria but underwent an evolutionary leap forward in basal metazoa that determined the currently known variations in mitophagy signaling.Abbreviations: AGPAT, 1-acylglycerol-3-phosphate O-acyltransferase; ATG, autophagy related; BCL2L13, BCL2 like 13; BNIP3, BCL2 interacting protein 3; BNIP3L, BCL2 interacting protein 3 like; CALCOCO, calcium binding and coiled-coil domain; CL, cardiolipin; ER, endoplasmic reticulum; ERMES, ER-mitochondria encounter structure; FBXL4, F-box and leucine rich repeat protein 4; FUNDC1, FUN14 domain containing 1; GABARAPL1, GABA type A receptor associated protein like 1; HIF, hypoxia inducible factor; IMM, inner mitochondrial membrane; LBPA/BMP, lysobisphosphatidic acid; LIR, LC3-interacting region; LPA, lysophosphatidic acid; MAM, mitochondria-associated membranes; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MCL, monolysocardiolipin; ML, maximum likelihood; NBR1, NBR1 autophagy cargo receptor; OMM, outer mitochondrial membrane; PA, phosphatidic acid; PACS2, phosphofurin acidic cluster sorting protein 2; PC/PLC, phosphatidylcholine; PE, phosphatidylethanolamine; PHB2, prohibitin 2; PINK1, PTEN induced kinase 1; PtdIns, phosphatidylinositol; SAR, Stramenopiles, Apicomplexa and Rhizaria; TAX1BP1, Tax1 binding protein 1; ULK1, unc-51 like autophagy activating kinase 1; VDAC/porin, voltage dependent anion channel.

Detrimental Roles of Hypoxia-Inducible Factor-1α in Severe Hypoxic Brain Diseases

Hypoxia stabilizes hypoxia-inducible factors (HIFs), facilitating adaptation to hypoxic conditions. Appropriate hypoxia is pivotal for neurovascular regeneration and immune cell mobilization. However, in central nervous system (CNS) injury, prolonged and severe hypoxia harms the brain by triggering neurovascular inflammation, oxidative stress, glial activation, vascular damage, mitochondrial dysfunction, and cell death. Diminished hypoxia in the brain improves cognitive function in individuals with CNS injuries. This review discusses the current evidence regarding the contribution of severe hypoxia to CNS injuries, with an emphasis on HIF-1α-mediated pathways. During severe hypoxia in the CNS, HIF-1α facilitates inflammasome formation, mitochondrial dysfunction, and cell death. This review presents the molecular mechanisms by which HIF-1α is involved in the pathogenesis of CNS injuries, such as stroke, traumatic brain injury, and Alzheimer's disease. Deciphering the molecular mechanisms of HIF-1α will contribute to the development of therapeutic strategies for severe hypoxic brain diseases.

Hypoxia enhances autophagy level of human sperms

The relationship between oxygen sensing and autophagy in human sperms was explored in this study. Health semen and asthenozoospermia (astheno) semen were incubated with hypoxia-inducible factor-1α (HIF-1α) interferents, i.e., lificiguat (YC-1) or cobalt chloride (CoCl2), respectively. Label-free quantitative proteomic technology was used to identify the differentially expressed proteins in human semen under the hypoxia condition. Selected proteins were detected with ELISA. It was found that the autophagy levels of sperm in the YC-1 + health group or CoCl2 + astheno group increased while the vitality decreased. A total of 17, 34 and 35 differentially expressed proteins were observed in the Astheno group, the YC-1 + health group and the CoCl2 + astheno group, respectively. These proteins were primarily associated with protein processing in endoplasmic reticulum, Th17 cell differentiation, progesterone-mediated oocyte maturation, glycolysis/gluconeogenesis, HIF-1 signaling pathway, biosynthesis of amino acids, and carbon metabolism. The expression levels of protein HIF-1α, LC3B, histone H4, cathepsin L and ENO1 changed significantly in the groups. The study suggests that hypoxia can increase sperm autophagy level and reduce their vitality through HIF-1 signaling pathway and glycolysis/gluconeogenesis signaling pathway. Furthermore, proteins histone H4, cathepsin L, glutathione synthetase and ENO1 are proposed as potential biomarkers of autophagy and vitality in asthenozoospermia sperm.

ZnO Nanorods Create a Hypoxic State with Induction of HIF-1 and EPAS1, Autophagy, and Mitophagy in Cancer and Non-Cancer Cells

Nanomaterials are gaining increasing attention as innovative materials in medicine. Among nanomaterials, zinc oxide (ZnO) nanostructures are particularly appealing because of their opto-electrical, antimicrobial, and photochemical properties. Although ZnO is recognized as a safe material and the Zn ion (Zn²⁺) concentration is strictly regulated at a cellular and systemic level, different studies have demonstrated cellular toxicity of ZnO nanoparticles (ZnO-NPs) and ZnO nanorods (ZnO-NRs). Recently, ZnO-NP toxicity has been shown to depend on the intracellular accumulation of ROS, activation of autophagy and mitophagy, as well as stabilization and accumulation of hypoxia-inducible factor-1α (HIF-1α) protein. However, if the same pathway is also activated by ZnO-NRs and how non-cancer cells respond to ZnO-NR treatment, are still unknown. To answer to these questions, we treated epithelial HaCaT and breast cancer MCF-7 cells with different ZnO-NR concentrations. Our results showed that ZnO-NR treatments increased cell death through ROS accumulation, HIF-1α and endothelial PAS domain protein 1 (EPAS1) activation, and induction of autophagy and mitophagy in both cell lines. These results, while on one side, confirmed that ZnO-NRs can be used to reduce cancer growth, on the other side, raised some concerns on the activation of a hypoxic response in normal cells that, in the long run, could induce cellular transformation.