p53 directly suppresses BNIP3 expression to protect against hypoxia-induced cell death

Harnessing Nur77's mitochondrial apoptotic pathway: A promising therapeutic strategy for targeted disease intervention

The role of mitochondria in disease development cannot be overlooked, and the targeting of mitochondria for the treatment of disease has emerged as a significant area of research in recent years. Mitochondria are the control center of the intrinsic apoptotic pathway, and their normal functions are finely regulated by a series of complex mechanisms. The nuclear receptor Nur77 is closely related to the functions of the mitochondria and is an active pro-apoptotic member of the nuclear receptor superfamily. The translocation of Nur77 to the mitochondria can promote the conversion of the anti-apoptotic protein Bcl-2 to a pro-apoptotic state, disrupt the balance between mitochondrial fission and fusion, and inhibit mitophagy. These effects lead to irreversible damage to mitochondria and apoptosis, ultimately accelerating the progression of the disease. Here, we review the mechanism and targeted drug development of the mitochondrial apoptosis pathway activated by Nur77 in human diseases, helping to understand the new advances in disease treatment.

Progressive Deactivation of Hydroxylases Controls Hypoxia-Inducible Factor-1α-Coordinated Cellular Adaptation to Graded Hypoxia

Graded hypoxia is a common microenvironment in malignant solid tumors. As a central regulator in the hypoxic response, hypoxia-inducible factor-1 (HIF-1) can induce multiple cellular processes including glycolysis, angiogenesis, and necroptosis. How cells exploit the HIF-1 pathway to coordinate different processes to survive hypoxia remains unclear. We developed an integrated model of the HIF-1α network to elucidate the mechanism of cellular adaptation to hypoxia. By numerical simulations and bifurcation analysis, we found that HIF-1α is progressively activated with worsening hypoxia due to the sequential deactivation of the hydroxylases prolyl hydroxylase domain enzymes and factor inhibiting HIF (FIH). Bistable switches control the activation and deactivation processes. As a result, glycolysis, immunosuppression, angiogenesis, and necroptosis are orderly elicited in aggravating hypoxia. To avoid the excessive accumulation of lactic acid during glycolysis, HIF-1α induces monocarboxylate transporter and carbonic anhydrase 9 sequentially to export intracellular hydrogen ions, facilitating tumor cell survival. HIF-1α-induced miR-182 facilitates vascular endothelial growth factor production to promote angiogenesis under moderate hypoxia. The imbalance between accumulation and removal of lactic acid in severe hypoxia may result in acidosis and induce cell necroptosis. In addition, the deactivation of FIH results in the destabilization of HIF-1α in anoxia. Collectively, HIF-1α orchestrates the adaptation of tumor cells to hypoxia by selectively inducing its targets according to the severity of hypoxia. Our work may provide clues for tumor therapy by targeting the HIF-1 pathway.

Unveiling the Complexities: Exploring Mechanisms of Anthracyclineinduced Cardiotoxicity

The coexistence of cancer and heart disease, both prominent causes of illness and death, is further exacerbated by the detrimental impact of chemotherapy. Anthracycline-induced cardiotoxicity is an unfortunate side effect of highly effective therapy in treating different types of cancer; it presents a significant challenge for both clinicians and patients due to the considerable risk of cardiotoxicity. Despite significant progress in understanding these mechanisms, challenges persist in identifying effective preventive and therapeutic strategies, rendering it a subject of continued research even after three decades of intensive global investigation. The molecular targets and signaling pathways explored provide insights for developing targeted therapies, emphasizing the need for continued research to bridge the gap between preclinical understanding and clinical applications. This review provides a comprehensive exploration of the intricate mechanisms underlying anthracycline-induced cardiotoxicity, elucidating the interplay of various signaling pathways leading to adverse cellular events, including cardiotoxicity and death. It highlights the extensive involvement of pathways associated with oxidative stress, inflammation, apoptosis, and cellular stress responses, offering insights into potential and unexplored targets for therapeutic intervention in mitigating anthracycline-induced cardiac complications. A comprehensive understanding of the interplay between anthracyclines and these complexes signaling pathways is crucial for developing strategies to prevent or mitigate the associated cardiotoxicity. Further research is needed to outline the specific contributions of these pathways and identify potential therapeutic targets to improve the safety and efficacy of anthracycline-based cancer treatment. Ultimately, advancements in understanding anthracycline-induced cardiotoxicity mechanisms will facilitate the development of more efficacious preventive and treatment approaches, thereby improving outcomes for cancer patients undergoing anthracycline-based chemotherapy.

The Abl1 tyrosine kinase is a key player in doxorubicin-induced cardiomyopathy and its p53/p73 cell death mediated signaling differs in atrial and ventricular cardiomyocytes

BACKGROUND

Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling.

RESULTS

Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis.

CONCLUSIONS

The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.

Network-based integration of omics, physiological and environmental data in real-world Elbe estuarine Zander

Coastal and estuarine environments are under endogenic and exogenic pressures jeopardizing survival and diversity of inhabiting biota. Information of possible synergistic effects of multiple (a)biotic stressors and holobiont interaction are largely missing in estuaries like the Elbe but are of importance to estimate unforeseen effects on animals' physiology. Here, we seek to leverage host-transcriptional RNA-seq and gill mucus microbial 16S rRNA metabarcoding data coupled with physiological and abiotic measurements in a network analysis approach to decipher the impact of multiple stressors on the health of juvenile Sander lucioperca along one of the largest European estuaries. We find mesohaline areas characterized by gill tissue specific transcriptional responses matching osmosensing and tissue remodeling. Liver transcriptomes instead emphasized that zander from highly turbid areas were undergoing starvation which was supported by compromised body condition. Potential pathogenic bacteria, including Shewanella, Acinetobacter, Aeromonas and Chryseobacterium, dominated the gill microbiome along the freshwater transition and oxygen minimum zone. Their occurrence coincided with a strong adaptive and innate transcriptional immune response in host gill and enhanced energy demand in liver tissue supporting their potential pathogenicity. Taken together, we show physiological responses of a fish species and its microbiome to abiotic factors whose impact is expected to increase with consequences of climate change. We further present a method for the close-meshed detection of the main stressors and bacterial species with disease potential in a highly productive ecosystem.

Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential

Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/IGF1, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan regulation and can modulate or have an interaction with autophagy. The specific types of autophagy, such as mitophagy that degrades mitochondria, can regulate aging by affecting these organelles and eliminating those mitochondria with genomic mutations. Autophagy and its specific types contribute to the regulation of carcinogenesis and they are able to dually enhance or decrease cancer progression. Cancer hallmarks, including proliferation, metastasis, therapy resistance and immune reactions, are tightly regulated by autophagy, supporting the conclusion that autophagy is a promising target in cancer therapy.

Both Splice Variants of Zebrafish Tmem11 Localize to the Outer Membrane of Mitochondria

In mammalian and Drosophila systems, Transmembrane protein 11 (TMEM11) regulates mitochondrial morphology, mitophagy, and mitochondrial function. Here, we begin to expand these studies to the zebrafish model system. We identified two splice variants of tmem11 , which are both expressed during early development. In addition, we determined that both zebrafish Tmem11 proteins localize to the mitochondria using fluorescent tags and expression in cell culture. Consistent with recent data, biochemical fractionation indicates that Tmem11 is embedded in the outer membrane of mitochondria. Overall, these studies will provide new insights into the complex protein network that mediates mitochondrial physiology in the zebrafish.

Shen'ge Formula Protects Cardiac Function in Rats with Pressure Overload-Induced Heart Failure

Background

In China, Shen'ge formula (SGF), a Traditional Chinese Medicine blend crafted from ginseng and gecko, holds a revered place in the treatment of cardiovascular diseases. However, despite its prevalent use, the precise cardioprotective mechanisms of SGF remain largely uncharted. This study aims to fill this gap by delving deeper into SGF's therapeutic potential and underlying action mechanism, thus giving its traditional use a solid scientific grounding.

Methods

In this study, rats were subjected to abdominal aortic constriction (AAC) to generate pressure overload. Following AAC, we administered SGF and bisoprolol intragastrically at specified doses for two distinct durations: 8 and 24 weeks. The cardiac function post-treatment was thoroughly analyzed using echocardiography and histological examinations, offering insights into SGF's influence on vital cardiovascular metrics, and signaling pathways central to cardiac health.

Results

SGF exhibited promising results, significantly enhanced cardiac functions over both 8 and 24-week periods, evidenced by improved ejection fraction and fractional shortening while moderating left ventricular parameters. Noteworthy was SGF's role in the significant mitigation of myocardial hypertrophy and in fostering the expression of vital proteins essential for heart health by the 24-week mark. This intervention markedly altered the dynamics of the Akt/HIF-1α/p53 pathway, inhibiting detrimental processes while promoting protective mechanisms.

Conclusion

Our research casts SGF in a promising light as a cardioprotective agent in heart failure conditions induced by pressure overload in rats. Central to this protective shield is the modulation of the Akt/HIF-1α/p53 pathway, pointing to a therapeutic trajectory that leverages HIF-1α promotion and p53 nuclear transport inhibition.

Mechanisms and therapeutic targets of mitophagy after intracerebral hemorrhage

Mitochondria are dynamic organelles responsible for cellular energy production. In addition to regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, clearance of damaged organelles, signaling, and cell survival in the context of injury and pathology. In stroke, the mechanisms underlying brain injury secondary to intracerebral hemorrhage are complex and involve cellular hypoxia, oxidative stress, inflammatory responses, and apoptosis. Recent studies have shown that mitochondrial damage and autophagy are essential for neuronal metabolism and functional recovery after intracerebral hemorrhage, and are closely related to inflammatory responses, oxidative stress, apoptosis, and other pathological processes. Because hypoxia and inflammatory responses can cause secondary damage after intracerebral hemorrhage, the restoration of mitochondrial function and timely clearance of damaged mitochondria have neuroprotective effects. Based on studies on mitochondrial autophagy (mitophagy), cellular inflammation, apoptosis, ferroptosis, the BNIP3 autophagy gene, pharmacological and other regulatory approaches, and normobaric oxygen (NBO) therapy, this article further explores the neuroprotective role of mitophagy after intracerebral hemorrhage.

HDAC6 preserves BNIP3 expression and mitochondrial integrity by deacetylating p53 at lysine 320

HDAC6 has been reported as a deacetylase of p53 at multiple lysine residues, associated with the canonical functions of p53, such as apoptosis and tumor suppression. We have previously reported that p53 acetylation at the lysine 320 site accumulates due to the genetic ablation of HDAC6 in mice liver. However, the biological processes affected by K320 acetylation of p53 are yet to be elucidated. In this study, we demonstrate that K320 acetylation of p53 is regulated by HDAC6 deacetylase activity. HDAC6 knockout mouse brains exhibit a significant accumulation of K320 acetylated p53 compared to other tissues. The level of K320 acetylation of p53 inversely correlates with the level of BNIP3, a direct target of p53 and essential for mitophagy. Notably, overexpressing the deacetylation mimic K320R mutant p53 restored BNIP3 expression in HDAC6 knockout MEFs. Furthermore, we observed that neurons are particularly susceptible to the genetic ablation of HDAC6, impacting BNIP3 expression, which inversely correlates with the accumulation of abnormal mitochondria characterized by swollen cristae. Our findings suggest that HDAC6 plays a crucial role in maintaining BNIP3 expression by deacetylating p53 at the K320 site, which is linked to the structural integrity of mitochondria.

Acid ground nano-realgar processed product inhibits breast cancer by inducing mitophagy via the p53/BNIP3/NIX pathway

Breast cancer is a highly prevalent malignancy with the first morbidity and the primary reason for female cancer-related deaths worldwide. Acid ground nano-realgar processed product (NRPP) could inhibit breast cancer cell proliferation and induce autophagy in our previous research; however, the underlying mechanisms are still unclear. Therefore, this research aimed to verify whether NRPP induces breast cancer mitophagy and explore the mitophagy-mediated mechanism. Primarily, rhodamine-123 assay and transmission electron microscopy were applied to detect mitochondrial membrane potential (MMP) and ultrastructural changes in the MDA-MB-435S cells, respectively. Mito-Tracker Green/Lyso-Tracker Red staining, western blot, immunofluorescence and RT-PCR were used to explore molecular mechanisms of NRPP-induced mitophagy in vitro. MDA-MB-435S breast cancer xenograft models were established to assess the activity and mechanisms of NRPP in vivo. Our results showed that NRPP decreased MMP and increased autophagosome numbers in MDA-MB-435S cells and activated mitophagy. Furthermore, mitophagy was consolidated because mitochondria and lysosomes colocalized phenomenology were observed, and the expression of LC3II/I and COXIV was upregulated. Additionally, we found the p53/BNIP3/NIX pathway was activated. Finally, NRPP inhibited tumour growth and downregulated the levels of TNF-α, IL-1β and IL-6. Necrosis, damaged mitochondria and autophagosomes were observed in xenograft tumour cells, and proteins and mRNA levels of LC3, p53, BNIP3 and NIX were increased. Overall, NRPP inhibited MDA-MB-435S cell proliferation and tumour growth by inducing mitophagy via the p53/BNIP3/NIX pathway. Thus, NRPP is a promising candidate for breast cancer treatment.

p53 at the Crossroads between Doxorubicin-Induced Cardiotoxicity and Resistance: A Nutritional Balancing Act

Doxorubicin (DOX) is a highly effective chemotherapeutic drug, but its long-term use can cause cardiotoxicity and drug resistance. Accumulating evidence demonstrates that p53 is directly involved in DOX toxicity and resistance. One of the primary causes for DOX resistance is the mutation or inactivation of p53. Moreover, because the non-specific activation of p53 caused by DOX can kill non-cancerous cells, p53 is a popular target for reducing toxicity. However, the reduction in DOX-induced cardiotoxicity (DIC) via p53 suppression is often at odds with the antitumor advantages of p53 reactivation. Therefore, in order to increase the effectiveness of DOX, there is an urgent need to explore p53-targeted anticancer strategies owing to the complex regulatory network and polymorphisms of the p53 gene. In this review, we summarize the role and potential mechanisms of p53 in DIC and resistance. Furthermore, we focus on the advances and challenges in applying dietary nutrients, natural products, and other pharmacological strategies to overcome DOX-induced chemoresistance and cardiotoxicity. Lastly, we present potential therapeutic strategies to address key issues in order to provide new ideas for increasing the clinical use of DOX and improving its anticancer benefits.

MDMX elevation by a novel Mdmx-p53 interaction inhibitor mitigates neuronal damage after ischemic stroke

Mdmx and Mdm2 are two major suppressor factors for the tumor suppressor gene p53. In central nervous system, Mdmx suppresses the transcriptional activity of p53 and enhances the binding of Mdm2 to p53 for degradation. But Mdmx dynamics in cerebral infarction remained obscure. Here we investigated the role of Mdmx under ischemic conditions and evaluated the effects of our developed small-molecule Protein-Protein Interaction (PPI) inhibitors, K-181, on Mdmx-p53 interactions in vivo and in vitro. We found ischemic stroke decreased Mdmx expression with increased phosphorylation of Mdmx Serine 367, while Mdmx overexpression by AAV-Mdmx showed a neuroprotective effect on neurons. The PPI inhibitor, K-181 attenuated the neurological deficits by increasing Mdmx expression in post-stroke mice brain. Additionally, K-181 selectively inhibited HDAC6 activity and enhanced tubulin acetylation. Our findings clarified the dynamics of Mdmx in cerebral ischemia and provide a clue for the future pharmaceutic development of ischemic stroke.

Jatrorrhizine reduces myocardial infarction-induced apoptosis and fibrosis through inhibiting p53 and TGF-β1/Smad2/3 pathways in mice

PURPOSE

To explore the mechanism of jatrorrhizine on apoptosis and fibrosis induced by myocardial infarction (MI) in an animal model.

METHODS

The left anterior descending branch of coronary artery was surgically ligated to duplicate the mouse model of MI. The sham and infarcted mice were treated with normal saline once a day, while mice in experimental groups received low-dose (LD) and high-dose (HD) jatrorrhizine once a day respectively. Two weeks later, cardiac function was detected by echocardiography, and histopathological examination was performed using hematoxylin and eosin (H&E) and Masson staining. The expressions of p53, TGF-β1, Smad/2/3, Bax, Bcl-2, collagen I and collagen III were quantified using qRT-PCR and western blot assays.

RESULTS

Jatrorrhizine significantly improved left ventricular ejection fraction (LVEF) and left ventricle end-systolic (LVES) in mice. Histopathological, administration of jatrorrhizine weakened infiltration of inflammatory cells and cardiac fibrosis in myocardium of mice caused by MI. Additionally, jatrorrhizine suppressed cardiomyocyte apoptosis exhibited as its capability to reverse changes of Bax and Bcl-2 levels in myocardium caused by MI. Jatrorrhizine statistically significantly downregulated expression of collagen I and collagen III, as well as TGF-β1, Smad2/3 and p53.

CONCLUSIONS

Jatrorrhizine reduce cardiomyocyte apoptosis and fibrosis through inhibiting p53/Bax/Bcl-2 and TGF-β1/Smad2/3 signaling pathways.

Molecular basis and clinical implications of HIFs in cardiovascular diseases

Oxygen maintains the homeostasis of an organism in a delicate balance in different tissues and organs. Under hypoxic conditions, hypoxia-inducible factors (HIFs) are specific and dominant factors in the spatiotemporal regulation of oxygen homeostasis. As the most basic functional unit of the heart at the cellular level, the cardiomyocyte relies on oxygen and nutrients delivered by the microvasculature to keep the heart functioning properly. Under hypoxic stress, HIFs are involved in acute and chronic myocardial pathology because of their spatiotemporal specificity, thus granting them therapeutic potential. Most adult animals lack the ability to regenerate their myocardium entirely following injury, and complete regeneration has long been a goal of clinical treatment for heart failure. The precise manipulation of HIFs (considering their dynamic balance and transformation) and the development of HIF-targeted drugs is therefore an extremely attractive cardioprotective therapy for protecting against myocardial ischemic and hypoxic injury, avoiding myocardial remodeling and heart failure, and promoting recovery of cardiac function.

The complexity of p53-mediated metabolic regulation in tumor suppression

Although the classic activities of p53 including induction of cell-cycle arrest, senescence, and apoptosis are well accepted as critical barriers to cancer development, accumulating evidence suggests that loss of these classic activities is not sufficient to abrogate the tumor suppression activity of p53. Numerous studies suggest that metabolic regulation contributes to tumor suppression, but the mechanisms by which it does so are not completely understood. Cancer cells rewire cellular metabolism to meet the energetic and substrate demands of tumor development. It is well established that p53 suppresses glycolysis and promotes mitochondrial oxidative phosphorylation through a number of downstream targets against the Warburg effect. The role of p53-mediated metabolic regulation in tumor suppression is complexed by its function to promote both cell survival and cell death under different physiological settings. Indeed, p53 can regulate both pro-oxidant and antioxidant target genes for complete opposite effects. In this review, we will summarize the roles of p53 in the regulation of glucose, lipid, amino acid, nucleotide, iron metabolism, and ROS production. We will highlight the mechanisms underlying p53-mediated ferroptosis, AKT/mTOR signaling as well as autophagy and discuss the complexity of p53-metabolic regulation in tumor development.

BNIP3 and Nix: Atypical regulators of cell fate

Since their discovery nearly 25 years ago, the BCL-2 family members BNIP3 and BNIP3L (aka Nix) have been labelled 'atypical'. Originally, this was because BNIP3 and Nix have divergent BH3 domains compared to other BCL-2 proteins. In addition, this atypical BH3 domain is dispensable for inducing cell death, which is also unusual for a 'death gene'. Instead, BNIP3 and Nix utilize a transmembrane domain, which allows for dimerization and insertion into and through organelle membranes to elicit cell death. Much has been learned regarding the biological function of these two atypical death genes, including their role in metabolic stress, where BNIP3 is responsive to hypoxia, while Nix responds variably to hypoxia and is also down-stream of PKC signaling and lipotoxic stress. Interestingly, both BNIP3 and Nix respond to signals related to cell atrophy. In addition, our current view of regulated cell death has expanded to include forms of necrosis such as necroptosis, pyroptosis, ferroptosis, and permeability transition-mediated cell death where BNIP3 and Nix have been shown to play context- and cell-type specific roles. Perhaps the most intriguing discoveries in recent years are the results demonstrating roles for BNIP3 and Nix outside of the purview of death genes, such as regulation of proliferation, differentiation/maturation, mitochondrial dynamics, macro- and selective-autophagy. We provide a historical and unbiased overview of these 'death genes', including new information related to alternative splicing and post-translational modification. In addition, we propose to redefine these two atypical members of the BCL-2 family as versatile regulators of cell fate.

Thymoquinone Alterations of the Apoptotic Gene Expressions and Cell Cycle Arrest in Genetically Distinct Triple-Negative Breast Cancer Cells

Breast cancer (BC) is the most common cancer in women worldwide, and it is one of the leading causes of cancer death in women. triple-negative breast Cancer (TNBC), a subtype of BC, is typically associated with the highest pathogenic grade and incidence in premenopausal and young African American (AA) women. Chemotherapy, the most common treatment for TNBC today, can lead to acquired resistance and ineffective treatment. Therefore, novel therapeutic approaches are needed to combat medication resistance and ineffectiveness in TNBC patients. Thymoquinone (TQ) is shown to have a cytotoxic effect on human cancer cells in vitro. However, TQ's mode of action and precise mechanism in TNBC disease in vitro have not been adequately investigated. Therefore, TQ's effects on the genetically different MDA-MB-468 and MDA-MB-231 human breast cancer cell lines were assessed. The data obtained show that TQ displayed cytotoxic effects on MDA-MB-468 and MDA-MB-231 cells in a time- and concentration-dependent manner after 24 h, with IC50 values of 25.37 µM and 27.39 µM, respectively. Moreover, MDA-MB-231 and MDA-MB-468 cells in a scratched wound-healing assay displayed poor wound closure, inhibiting invasion and migration via cell cycle blocking after 24 h. TQ arrested the cell cycle phase in MDA-MB-231 and MDA-MB-468 cells. The three cell cycle stages in MDA-MB-468 cells were significantly affected at 15 and 20 µM for G0/G1 and S phases, as well as all TQ concentrations for G2/M phases. In MDA-MB-468 cells, there was a significant decrease in G0/G1 phases with a substantial increase in the S phase and G2/M phases. In contrast, MDA-MB-231 showed a significant effect only during the two cell cycle stages (S and G2/M), at concentrations of 15 and 20 µM for S phases and all TQ values for G2/M phases. The TQ effect on the apoptotic gene profiles indicated that TQ upregulated 15 apoptotic genes in MDA-MB-231 TNBC cells, including caspases, GADD45A, TP53, DFFA, DIABLO, BNIP3, TRAF2/3, and TNFRSF10A. In MDA-MB-468 cells, 16 apoptotic genes were upregulated, including TNFRSF10A, TNF, TNFRSF11B, FADD TNFRSF10B, CASP2, and TRAF2, all of which are important for the apoptotic pathway andsuppress the expression of one anti-apoptotic gene, BIRC5, in MDA-MB-231 cells. Compared to MDA-MB-231 cells, elevated levels of TNF and their receptor proteins may contribute to their increased sensitivity to TQ-induced apoptosis. It was concluded from this study that TQ targets the MDA-MB-231 and MDA-MB-468 cells differently. Additionally, due to the aggressive nature of TNBC and the lack of specific therapies in chemoresistant TNBC, our findings related to the identified apoptotic gene profile may point to TQ as a potential agent for TNBC therapy.

Mammalian eIF4E2-GSK3β maintains basal phosphorylation of p53 to resist senescence under hypoxia

Hypoxia modulates senescence, but their physiological link remains unclear. Here, we found that eIF4E2, a hypoxia-activated translation initiation factor, interacted with GSK3β to maintain phosphorylation of p53, thus resisting senescence under hypoxia. RNA-binding protein RBM38 interacted with eIF4E to inhibit the translation of p53, but GSK3β-mediated Ser195 phosphorylation disrupted the RBM38-eIF4E interaction. Through investigation of RBM38 phosphorylation, we found that the eIF4E2-GSK3β pathway specifically regulated proline-directed serine/threonine phosphorylation (S/T-P). Importantly, peptides e2-I or G3-I that blocking eIF4E2-GSK3β interaction can inhibit the basal S/T-P phosphorylation of p53 at multiple sites, therby inducing senescence through transcriptional inhibition. Additionally, a nanobody was screened via the domain where eIF4E2 bound to GSK3β, and this nanobody inhibited S/T-P phosphorylation to promote senescence. Furthermore, hypoxia inhibited eIF4E2-GSK3β pathway by mediating S-Nitrosylation of GSK3β. Blocking eIF4E2-GSK3β interaction promoted liver senescence under hypoxia, thus leading to liver fibrosis, eventually accelerating N, N-diethylnitrosamine (DEN)-induced tumorigenesis. Interestingly, eIF4E2 isoforms with GSK3β-binding motif exclusively exist in mammals, which protect zebrafish heart against hypoxia. Together, this study reveals a mammalian eIF4E2-GSK3β pathway that prevents senescence by maintaining basal S/T-P phosphorylation of p53, which underlies hypoxia adaptation of tissues.

p53N236S Activates Autophagy in Response to Hypoxic Stress Induced by DFO

Hypoxia can lead to stabilization of the tumor suppressor gene p53 and cell death. However, p53 mutations could promote cell survival in a hypoxic environment. In this study, we found that p53N236S (p53N239S in humans, hereinafter referred to as p53S) mutant mouse embryonic fibroblasts (MEFs) resistant to deferoxamine (DFO) mimic a hypoxic environment. Further, Western blot and flow cytometry showed reduced apoptosis in p53S/S cells compared to WT after DFO treatment, suggesting an antiapoptosis function of p53S mutation in response to hypoxia-mimetic DFO. Instead, p53S/S cells underwent autophagy in response to hypoxia stress presumably through inhibition of the AKT/mTOR pathway, and this process was coupled with nuclear translocation of p53S protein. To understand the relationship between autophagy and apoptosis in p53S/S cells in response to hypoxia, the autophagic inhibitor 3-MA was used to treat both WT and p53S/S cells after DFO exposure. Both apoptotic signaling and cell death were enhanced by autophagy inhibition in p53S/S cells. In addition, the mitochondrial membrane potential (MMP) and the ROS level results indicated that p53S might initiate mitophagy to clear up damaged mitochondria in response to hypoxic stress, thus increasing the proportion of intact mitochondria and maintaining cell survival. In conclusion, the p53S mutant activates autophagy instead of inducing an apoptotic process in response to hypoxia stress to protect cells from death.

Mitophagy in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the most common cause of end-stage kidney disease worldwide and is the main microvascular complication of diabetes. The increasing prevalence of diabetes has increased the need for effective treatment of DKD and identification of new therapeutic targets for better clinical management. Mitophagy is a highly conserved process that selectively removes damaged or unnecessary mitochondria via the autophagic machinery. Given the important role of mitophagy in the increased risk of DKD, especially with the recent surge in COVID-19-associated diabetic complications, in this review, we provide compelling evidence for maintaining homeostasis in the glomeruli and tubules and its underlying mechanisms, and offer new insights into potential therapeutic approaches for treatment of DKD.

Oxygen-Releasing Biomaterials: Current Challenges and Future Applications

Oxygen is essential for the survival, function, and fate of mammalian cells. Oxygen tension controls cellular behaviour via metabolic programming, which in turn controls tissue regeneration, stem cell differentiation, drug metabolism, and numerous pathologies. Thus, oxygen-releasing biomaterials represent a novel and unique strategy to gain control over a variety of in vivo processes. Consequently, numerous oxygen-generating or carrying materials have been developed in recent years, which offer innovative solutions in the field of drug efficiency, regenerative medicine, and engineered living systems. In this review, we discuss the latest trends, highlight current challenges and solutions, and provide a future perspective on the field of oxygen-releasing materials.

Comparative cardioprotective effects of carvedilol versus atenolol in a rat model of cardiorenal syndrome type 4

The incidence of chronic kidney disease is escalating; cardiorenal syndrome (CRS) type 4 is gaining a major health concern causing significant morbidity and mortality, putting major burdens on the healthcare system. This study was designed to compare the cardioprotective effects of carvedilol versus atenolol against CRS type 4 induced by subtotal 5/6 nephrectomy in rats and to explore the underlying mechanisms. Immediately after surgery, carvedilol (20 mg/kg/day) or atenolol (20 mg/kg/day) was added to drinking water for 10 weeks. Carvedilol was more effective than atenolol in improving kidney functions, decreasing elevated blood pressures, attenuating cardiac hypertrophy, reducing serum brain natriuretic peptide, and diminished cardiac fibrous tissue deposition. However, carvedilol was equivalent to atenolol in modulating β1-adrenergic receptors (β1ARs) and cardiac diacylglycerol (DAG) signaling, but carvedilol was superior in modulating β-arrestin2, phosphatidyl inositol 4,5 bisphosphates (PIP2), and caspase 3 levels. Carvedilol has superior cardioprotective effects than atenolol in a rat model of CRS type 4. These protective effects are mediated through modulating cardiac β1ARs/β-arrestin2/PIP2/DAG as well as abating cardiac apoptotic signaling pathways (caspase3/pS473 protein kinase B (Akt)).

Integrative Transcriptomic Analysis Reveals the Immune Mechanism for a CyHV-3-Resistant Common Carp Strain

Anti-disease breeding is becoming the most promising solution to cyprinid herpesvirus-3 (CyHV-3) infection, the major threat to common carp aquaculture. Virus challenging studies suggested that a breeding strain of common carp developed resistance to CyHV-3 infection. This study illustrates the immune mechanisms involved in both sensitivity and anti-virus ability for CyHV3 infection in fish. An integrative analysis of the protein-coding genes and long non-coding RNAs (lncRNAs) using transcriptomic data was performed. Tissues from the head kidney of common carp were extracted at days 0 (the healthy control) and 7 after CyHV-3 infection (the survivors) and used to analyze the transcriptome through both Illumina and PacBio sequencing. Following analysis of the GO terms and KEGG pathways involved, the immune-related terms and pathways were merged. To dig out details on the immune aspect, the DEGs were filtered using the current common carp immune gene library. Immune gene categories and their corresponding genes in different comparison groups were revealed. Also, the immunological Gene Ontology terms for lncRNA modulation were retained. The weighted gene co-expression network analysis was used to reveal the regulation of immune genes by lncRNA. The results demonstrated that the breeding carp strain develops a marked resistance to CyHV-3 infection through a specific innate immune mechanism. The featured biological processes were autophagy, phagocytosis, cytotoxicity, and virus blockage by lectins and MUC3. Moreover, the immune-suppressive signals, such as suppression of IL21R on STAT3, PI3K mediated inhibition of inflammation by dopamine upon infection, as well as the inhibition of NLRC3 on STING during a steady state. Possible susceptible factors for CyHV-3, such as ITGB1, TLR18, and CCL4, were also revealed from the non-breeding strain. The results of this study also suggested that Nramp and PAI regulated by LncRNA could facilitate virus infection and proliferation for infected cells respectively, while T cell leukemia homeobox 3 (TLX3), as well as galectin 3 function by lncRNA, may play a role in the resistance mechanism. Therefore, immune factors that are immunogenetically insensitive or susceptible to CyHV-3 infection have been revealed.

Electroacupuncture at GV20‑GB7 regulates mitophagy to protect against neurological deficits following intracerebral hemorrhage via inhibition of apoptosis

The acupuncture penetrating line of Baihui (GV20) to Qubin (GB7) spans the parietal, frontal and temporal lobes. The present study aimed to elucidate the mechanism by which electroacupuncture (EA) at GV20‑GB7 regulates mitophagy in intracerebral hemorrhage (ICH) and whether it serves a neuroprotective role. A whole blood‑induced ICH model was used. Mitophagy‑regulating proteins, including BCL/adenovirus E1B 19 kDa‑interacting protein 3 (BNIP3), PTEN‑induced putative kinase 1 (PINK1), Parkin and apoptosis‑associated proteins were detected by western blotting; autophagy following ICH was evaluated by immunofluorescent techniques; morphological characteristics of mitophagy were observed using transmission electron microscopy; and TUNEL assay was performed to determine the number of apoptotic cells. Immunohistochemistry was used to detect p53 expression. The protective role of EA (GV20‑GB7) via enhanced mitophagy and suppressed apoptosis in ICH was further confirmed by decreased modified neurological severity score. The results showed that EA (GV20‑GB7) treatment upregulated mitochondrial autophagy following ICH and inhibited apoptotic cell death. The mechanism underlying EA (GV20‑GB7) treatment may involve inhibition of p53, an overlapping protein of autophagy and apoptosis. EA (GV20‑GB7) treatment decreased neurobehavioral deficits following ICH but pretreatment with 3‑methyladenine counteracted the beneficial effects of EA (GV20‑GB7) treatment. In conclusion, EA (GV20‑GB7) improved recovery from ICH by regulating the balance between mitophagy and apoptosis.

Mitophagy in tumorigenesis and metastasis

Cells use mitophagy to remove dysfunctional or excess mitochondria, frequently in response to imposed stresses, such as hypoxia and nutrient deprivation. Mitochondrial cargo receptors (MCR) induced by these stresses target mitochondria to autophagosomes through interaction with members of the LC3/GABARAP family. There are a growing number of these MCRs, including BNIP3, BNIP3L, FUNDC1, Bcl2-L-13, FKBP8, Prohibitin-2, and others, in addition to mitochondrial protein targets of PINK1/Parkin phospho-ubiquitination. There is also an emerging link between mitochondrial lipid signaling and mitophagy where ceramide, sphingosine-1-phosphate, and cardiolipin have all been shown to promote mitophagy. Here, we review the upstream signaling mechanisms that regulate mitophagy, including components of the mitochondrial fission machinery, AMPK, ATF4, FoxOs, Sirtuins, and mtDNA release, and address the significance of these pathways for stress responses in tumorigenesis and metastasis. In particular, we focus on how mitophagy modulators intersect with cell cycle control and survival pathways in cancer, including following ECM detachment and during cell migration and metastasis. Finally, we interrogate how mitophagy affects tissue atrophy during cancer cachexia and therapy responses in the clinic.

Exosomal LINC00174 derived from vascular endothelial cells attenuates myocardial I/R injury via p53-mediated autophagy and apoptosis

In this study, we aim to investigate the regulation of specific long non-coding RNAs (lncRNAs) on the progression of ischemia/reperfusion (I/R) injury. We identified and characterized the exosomes derived from mouse primary aortic endothelial cells. Subsequently, we found that these exosomes expressed typical exosomal markers and high levels of LINC00174, which significantly ameliorated I/R-induced myocardial damage and suppressed the apoptosis, vacuolation, and autophagy of myocardial cells. Mechanistic approaches revealed that LINC00174 directly interacted with SRSF1 to suppress the expression of p53, thus restraining the transcription of myocardin and repressing the activation of the Akt/AMPK pathway that was crucial for autophagy initiation in I/R-induced myocardial damage. Moreover, this molecular mechanism was verified by in vivo study. In summary, exosomal LINC00174 generated from vascular endothelial cells repressed p53-mediated autophagy and apoptosis to mitigate I/R-induced myocardial damage, suggesting that targeting LINC00174 may be a novel strategy to treat I/R-induced myocardial infarction.

The Interplay Between Tumor Suppressor p53 and Hypoxia Signaling Pathways in Cancer

Hypoxia is a hallmark of solid tumors and plays a critical role in different steps of tumor progression, including proliferation, survival, angiogenesis, metastasis, metabolic reprogramming, and stemness of cancer cells. Activation of the hypoxia-inducible factor (HIF) signaling plays a critical role in regulating hypoxic responses in tumors. As a key tumor suppressor and transcription factor, p53 responds to a wide variety of stress signals, including hypoxia, and selectively transcribes its target genes to regulate various cellular responses to exert its function in tumor suppression. Studies have demonstrated a close but complex interplay between hypoxia and p53 signaling pathways. The p53 levels and activities can be regulated by the hypoxia and HIF signaling differently depending on the cell/tissue type and the severity and duration of hypoxia. On the other hand, p53 regulates the hypoxia and HIF signaling at multiple levels. Many tumor-associated mutant p53 proteins display gain-of-function (GOF) oncogenic activities to promote cancer progression. Emerging evidence has also shown that GOF mutant p53 can promote cancer progression through its interplay with the hypoxia and HIF signaling pathway. In this review, we summarize our current understanding of the interplay between the hypoxia and p53 signaling pathways, its impact upon cancer progression, and its potential application in cancer therapy.

Regulation of HIF-1α and p53 in stress responses in the subterranean rodents Lasiopodomys mandarinus and Lasiopodomys brandtii (Rodentia: Cricetidae)

The response mechanism and interaction patterns of HIF-1α and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1α and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1α and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1α and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1α and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus. Correlation analysis revealed that HIF-1α expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii, both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii. We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1α in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Huoxin pill attenuates myocardial infarction-induced apoptosis and fibrosis via suppression of p53 and TGF-β1/Smad2/3 pathways

Huoxin Pill (HXP), a Traditional Chinese Medicine, is used widely to treat patients with coronary heart disease and angina pectoris in China. However, the underlying protective mechanism of HXP on cardiac apoptosis and fibrosis has never been evaluated. Therefore, the aim of this study was to investigate the role of HXP in a myocardial infarction (MI) mouse model. The mice were randomly divided into 3 groups and subjected to surgical ligation of the left anterior descending (LAD) coronary artery or sham surgery (n = 6 for each group) and treated with HXP (50 mg/kg/day) or saline by gavage for 2 weeks. At 2 weeks post MI, we found that HXP significantly enhanced myocardial function and attenuated the increase of heart weight index (HWI) and pathological changes in MI mice. RNA-sequencing and KEGG pathway analyses identified 660 differentially expressed genes and multiple enriched signaling pathways including p53 and TGF-β. In support of these findings, HXP attenuated cardiac apoptosis and decreased p53 and Bax protein expression, while increasing Bcl-2 protein expression in cardiac tissues of MI mice. Furthermore, HXP treatment inhibited cardiac fibrosis and significantly down-regulated TGF-β1 protein expression and Smad2/3 phosphorylation in cardiac tissues. In summary, HXP can improve cardiac function in mice after MI by attenuating cardiac apoptosis and fibrosis partly via supression of the p53/Bax/Bcl-2 and TGF-β1/Smad2/3 pathways.

Mitophagy and Mitochondrial Dysfunction in Cancer

The process of mitophagy, in which mitochondria are selectively turned over at the autophagolysosome, plays a central role in both eliminating dysfunctional mitochondria and reducing mitochondrial mass as an adaptive response to key physiological stresses, such as hypoxia, nutrient deprivation, and DNA damage. Defects in mitophagy have been linked to altered mitochondrial metabolism, production of excess reactive oxygen species and ferroptosis, heightened inflammasome activation, altered cell fate decisions, and senescence, among other cellular consequences. Consequently, functional mitophagy contributes to proper tissue differentiation and repair and metabolic homeostasis, limiting inflammatory responses and modulating tumor progression and metastasis. This review examines the major pathways that control mitophagy, including PINK1-dependent mitophagy and BNIP3/NIX-dependent mitophagy. It also discusses the cellular signaling mechanisms used to sense mitochondrial dysfunction to activate mitophagy and how defective mitophagy results in deregulated tumor cell growth and cancer.

Mitochondria in Embryogenesis: An Organellogenesis Perspective

Organogenesis is well characterized in vertebrates. However, the anatomical and functional development of intracellular compartments during this phase of development remains unknown. Taking an organellogenesis point of view, we characterize the spatiotemporal adaptations of the mitochondrial network during zebrafish embryogenesis. Using state of the art microscopy approaches, we find that mitochondrial network follows three distinct distribution patterns during embryonic development. Despite of this constant morphological change of the mitochondrial network, electron transport chain supercomplexes occur at early stages of embryonic development and conserve a stable organization throughout development. The remodeling of the mitochondrial network and the conservation of its structural components go hand-in-hand with somite maturation; for example, genetic disruption of myoblast fusion impairs mitochondrial network maturation. Reciprocally, mitochondria quality represents a key factor to determine embryonic progression. Alteration of mitochondrial polarization and electron transport chain halts embryonic development in a reversible manner suggesting developmental checkpoints that depend on mitochondrial integrity. Our findings establish the subtle dialogue and co-dependence between organogenesis and mitochondria in early vertebrate development. They also suggest the importance of adopting subcellular perspectives to understand organelle-organ communications during embryogenesis.

Transplanted Mesenchymal Stem Cells Reduce Autophagic Flux in Infarcted Hearts via the Exosomal Transfer of miR-125b

RATIONALE

Autophagy can preserve cell viability under conditions of mild ischemic stress by degrading damaged organelles for ATP production, but under conditions of severe ischemia, it can promote cell death and worsen cardiac performance. Mesenchymal stem cells (MSCs) are cardioprotective when tested in animal models of myocardial infarction, but whether these benefits occur through the regulation of autophagy is unknown.

OBJECTIVE

To determine whether transplanted MSCs reduce the rate of autophagic degradation (autophagic flux) in infarcted hearts and if so, to characterize the mechanisms involved.

METHODS AND RESULTS

Treatment with transplanted MSCs improved cardiac function and infarct size while reducing apoptosis and measures of autophagic flux (bafilomycin A1-induced LC3-II [microtubule-associated protein 1 light chain 3] accumulation and autophagosome/autolysosome prevalence) in infarcted mouse hearts. In hypoxia and serum deprivation-cultured neonatal mouse cardiomyocytes, autophagic flux and cell death, as well as p53-Bnip3 (B-cell lymphoma 2-interacting protein 3) signaling, declined when the cells were cultured with MSCs or MSC-secreted exosomes (MSC-exo), but the changes associated with MSC-exo were largely abolished by pretreatment with the exosomal inhibitor GW4869. Furthermore, a mimic of the exosomal oligonucleotide miR-125b reduced, whereas an anti-miR-125b oligonucleotide increased, autophagic flux and cell death, via modulating p53-Bnip3 signaling in hypoxia and serum deprivation-cultured neonatal mouse cardiomyocytes. In the in vivo mouse myocardial infarction model, MSC-exo, but not the exosomes obtained from MSCs pretreated with the anti-miR-125b oligonucleotide (MSC-exo^{anti-miR-125b}), recapitulated the same results as the in vitro experiments. Moreover, measurements of infarct size and cardiac function were significantly better in groups that were treated with MSC-exo than the MSC-exo^{anti-miR-125b} group.

CONCLUSIONS

The beneficial effects offered by MSC transplantation after myocardial infarction are at least partially because of improved autophagic flux through excreted exosome containing mainly miR-125b-5p.

Autophagy and cancer cell metabolism

Autophagy is an ancient catabolic process used by cells to clear excess or dysfunctional organelles and large subcellular structures and thus performs an important housekeeping role for the cell. Autophagy is acutely sensitive to nutrient availability and is upregulated at a transcriptional and posttranslational level in response to nutrient deprivation. This serves to promote turnover of cellular content and recycling of nutrients for continued growth and survival. While important for most normal tissues, tumor cells appear to be particularly dependent on autophagy for survival under ischemic or therapeutic stress, and in response to loss of matrix attachment; autophagy is upregulated markedly in cancers as they progress to malignancy. Ras-driven tumors appear to be particularly dependent on autophagy and thus inhibition of autophagy is being pursued as a productive clinical approach for such cancers. However, this enthusiasm needs to be offset against possible negative effects of autophagy inhibition on normal tissue function and on limiting antitumor immune responses. In addressing all of these topics, we focus in on understanding how autophagy is induced by nutrient stress, its role in recycling metabolites for growing tumors, how selective forms of autophagy, such as mitophagy and ribophagy contribute specifically to tumorigenesis, how autophagy in the tumor microenvironment and throughout the animal affects access of the tumor to nutrients, and finally how different oncogenic pathways may determine which tumors respond to autophagy inhibition and which ones will not.

Mitochondria as playmakers of apoptosis, autophagy and senescence

Mitochondria are the key energy-producing organelles and cellular source of reactive species. They are responsible for managing cell life and death by a balanced homeostasis passing through a network of structures, regulated principally via fission and fusion. Herein we discuss about the most advanced findings considering mitochondria as dynamic biophysical systems playing compelling roles in the regulation of energy metabolism in both physiologic and pathologic processes controlling cell death and survival. Precisely, we focus on the mitochondrial commitment to the onset, maintenance and counteraction of apoptosis, autophagy and senescence in the bioenergetic reprogramming of cancer cells. In this context, looking for a pharmacological manipulation of cell death processes as a successful route for future targeted therapies, there is major biotechnological challenge in underlining the location, function and molecular mechanism of mitochondrial proteins. Based on the critical role of mitochondrial functions for cellular health, a better knowledge of the main molecular players in mitochondria disfunction could be decisive for the therapeutical control of degenerative diseases, including cancer.

p53/BNIP3-dependent mitophagy limits glycolytic shift in radioresistant cancer

The role of p53 in genotoxic therapy-induced metabolic shift in cancers is not yet known. In this study, we investigated the role of p53 in the glycolytic shift in head and neck squamous cell carcinoma cell lines following irradiation. Isogenic p53-null radioresistant cancer cells established through cumulative irradiation showed decreased oxygen consumption and increased glycolysis with compromised mitochondria, corresponding with their enhanced sensitivity to drugs that target glycolysis. In contrast, radioresistant cancer cells with wild-type p53 preserved their primary metabolic profile with intact mitophagic processes and maintained their mitochondrial integrity. Moreover, we identified a previously unappreciated link between p53 and mitophagy, which limited the glycolytic shift through the BNIP3-dependent clearance of abnormal mitochondria. Thus, drugs targeting glycolysis could be used as an alternative strategy for overcoming radioresistant cancers, and the p53 status could be used as a biomarker for selecting participants for clinical trials.

Evolving and Expanding the Roles of Mitophagy as a Homeostatic and Pathogenic Process

The central functions fulfilled by mitochondria as both energy generators essential for tissue homeostasis and gateways to programmed apoptotic and necrotic cell death mandate tight control over the quality and quantity of these ubiquitous endosymbiotic organelles. Mitophagy, the targeted engulfment and destruction of mitochondria by the cellular autophagy apparatus, has conventionally been considered as the mechanism primarily responsible for mitochondrial quality control. However, our understanding of how, why, and under what specific conditions mitophagy is activated has grown tremendously over the past decade. Evidence is accumulating that nonmitophagic mitochondrial quality control mechanisms are more important to maintaining normal tissue homeostasis whereas mitophagy is an acute tissue stress response. Moreover, previously unrecognized mitophagic regulation of mitochondrial quantity control, metabolic reprogramming, and cell differentiation suggests that the mechanisms linking genetic or acquired defects in mitophagy to neurodegenerative and cardiovascular diseases or cancer are more complex than simple failure of normal mitochondrial quality control. Here, we provide a comprehensive overview of mitophagy in cellular homeostasis and disease and examine the most revolutionary concepts in these areas. In this context, we discuss evidence that atypical mitophagy and nonmitophagic pathways play central roles in mitochondrial quality control, functioning that was previously considered to be the primary domain of mitophagy.

Mitophagy, a potential therapeutic target for stroke

Mitochondria autophagy, termed as mitophagy, is a mechanism of specific autophagic elimination of mitochondria. Mitophagy controls the quality and the number of mitochondria, eliminating dysfunctional or excessive mitochondria that can generate reactive oxygen species (ROS) and cause cell death. Mitochondria are centrally implicated in neuron and tissue injury after stroke, due to the function of supplying adenosine triphosphate (ATP) to the tissue, regulating oxidative metabolism during the pathologic process, and contribution to apoptotic cell death after stroke. As a catabolic mechanism, mitophagy links numbers of a complex network of mitochondria, and affects mitochondrial dynamic process, fusion and fission, reducing mitochondrial production of ROS, mediated by the mitochondrial permeability transition pore (MPTP). The precise nature of mitophagy’s involvement in stroke, and its underlying molecular mechanisms, have yet to be fully clarified. This review aims to provide a comprehensive overview of the integration of mitochondria with mitophagy, also to introduce and discuss recent advances in the understanding of the potential role, and possible signaling pathway, of mitophagy in the pathological processes of both hemorrhagic and ischemic stroke. The author also provides evidence to explain the dual role of mitophagy in stroke.

DNA methylation of the promoter region of bnip3 and bnip3l genes induced by metabolic programming

BACKGROUND

Environmental changes of biotic or abiotic nature during critical periods of early development may exert a profound influence on physiological functions later in life. This process, named developmental programming can also be driven through parental nutrition. At molecular level, epigenetic modifications are the most likely candidate for persistent modulation of genes expression in later life.

RESULTS

In order to investigate epigenetic modifications induced by programming in rainbow trout, we focused on bnip3 and bnip3l paralogous genes known to be sensitive to environmental changes but also regulated by epigenetic modifications. Two specific stimuli were used: (i) early acute hypoxia applied at embryo stage and (ii) broodstock and fry methionine deficient diet, considering methionine as one of the main methyl-group donor needed for DNA methylation. We observed a programming effect of hypoxia with an increase of bnip3a and the four paralogs of bnip3l expression level in fry. In addition, parental methionine nutrition was correlated to bnip3a and bnip3lb1 expression showing evidence for early fry programming. We highlighted that both stimuli modified DNA methylation levels at some specific loci of bnip3a and bnip3lb1.

CONCLUSION

Overall, these data demonstrate that methionine level and hypoxia stimulus can be of critical importance in metabolic programming. Both stimuli affected DNA methylation of specific loci, among them, an interesting CpG site have been identified, namely - 884 bp site of bnip3a, and may be positively related with mRNA levels.

Hypoxia and Selective Autophagy in Cancer Development and Therapy

Low oxygen availability, a condition known as hypoxia, is a common feature of various pathologies including stroke, ischemic heart disease, and cancer. Hypoxia adaptation requires coordination of intricate pathways and mechanisms such as hypoxia-inducible factors (HIFs), the unfolded protein response (UPR), mTOR, and autophagy. Recently, great effort has been invested toward elucidating the interplay between hypoxia-induced autophagy and cancer cell metabolism. Although novel types of selective autophagy have been identified, including mitophagy, pexophagy, lipophagy, ERphagy and nucleophagy among others, their potential interface with hypoxia response mechanisms remains poorly understood. Autophagy activation facilitates the removal of damaged cellular compartments and recycles components, thus promoting cell survival. Importantly, tumor cells rely on autophagy to support self-proliferation and metastasis; characteristics related to poor disease prognosis. Therefore, a deeper understanding of the molecular crosstalk between hypoxia response mechanisms and autophagy could provide important insights with relevance to cancer and hypoxia-related pathologies. Here, we survey recent findings implicating selective autophagy in hypoxic responses, and discuss emerging links between these pathways and cancer pathophysiology.

A pathogen-derived effector modulates host glucose metabolism by arginine GlcNAcylation of HIF-1α protein

The essential role of pathogens in host metabolism is widely recognized, yet the mechanisms by which they affect host physiology remain to be fully defined. Here, we found that NleB, an enteropathogenic Escherichia coli (EPEC) type III secretion system effector known to possess N-acetylglucosamine (GlcNAc) transferase activity, GlcNAcylates HIF-1α, a master regulator of cellular O₂ homeostasis. We determined that NleB-mediated GlcNAcylation at a conserved arginine 18 (Arg18) at the N-terminus of HIF-1α enhanced HIF-1α transcriptional activity, thereby inducing HIF-1α downstream gene expression to alter host glucose metabolism. The arginine transferase activity of NleB was required for its enhancement of HIF-1α transactivity and the subsequent effect on glucose metabolism in a mouse model of EPEC infection. In addition, HIF-1α acted as a mediator to transact NleB-mediated induction of glucose metabolism-associated gene expression under hypoxia. Thus, our results further show a causal link between pathogen infection and host glucose metabolism, and we propose a new mechanism by which this occurs.

Accumulating evidence shows that pathogens can affect host metabolism, resulting in human diseases such as obesity and type 2 diabetes. However, how pathogens influence their hosts is still not clear, and this results in a lack of effective and specific clinical treatments. Further investigations into the causes of pathogen disturbance of host metabolism are urgently needed. In this study, we show that a protein molecule, NleB, secreted by enteropathogenic bacteria (EPEC) can get into host cells and modify the function of a master regulator of cellular O₂ homeostasis, HIF-1α, thereby altering host glucose metabolism. We show that HIF-1α acts as a mediator to transact NleB-mediated induction of glucose metabolism-associated gene expression under hypoxia. Our results reveal a causal link between pathogen infection and host glucose metabolism, which may provide a new explanation for the causes of human diseases related to metabolic disturbance.

Deletion of the fih gene encoding an inhibitor of hypoxia-inducible factors increases hypoxia tolerance in zebrafish

Many aerobic organisms have developed molecular mechanism to tolerate hypoxia, but the specifics of these mechanisms remain poorly understood. It is important to develop genetic methods that confer increased hypoxia tolerance to intensively farmed aquatic species, as these are maintained in environments with limited available oxygen. As an asparaginyl hydroxylase of hypoxia-inducible factors (HIFs), factor inhibiting HIF (FIH) inhibits transcriptional activation of hypoxia-inducible genes by blocking the association of HIFs with the transcriptional coactivators CREB-binding protein (CBP) and p300. Therefore, here we sought to test whether fih is involved in regulating hypoxia tolerance in the commonly used zebrafish model. Overexpressing the zebrafish fih gene in epithelioma papulosum cyprini (EPC) cells and embryos, we found that fih inhibits the transcriptional activation of zebrafish HIF-α proteins. Using CRISPR/Cas9 to obtain fih-null zebrafish mutants, we noted that the fih deletion makes zebrafish more tolerant of hypoxic conditions than their WT siblings, but does not result in oxygen consumption rates that significantly differ from those of WT fish. Of note, we identified fewer apoptotic cells in adult fih-null zebrafish brains and in fih-null embryos, possibly explaining why the fih-null mutant had greater hypoxia tolerance than the WT. Moreover, the fih deletion up-regulated several hypoxia-inducible genes in fih-null zebrafish exposed to hypoxia. The findings of our study suggest that fih plays a role in hypoxia tolerance by affecting the rate of cellular apoptosis in zebrafish.

Mst1 regulates colorectal cancer stress response via inhibiting Bnip3-related mitophagy by activation of JNK/p53 pathway

The Hippo-Mst1 pathway is associated with tumor development and progression. However, little evidence is available for its role in colorectal cancer (CRC) stress response via mitochondrial homeostasis. In this study, we conducted gain-of function assay about Mst1 in CRC via adenovirus transfection. Then, cellular viability and apoptosis were measured via MTT, TUNEL assay, and typan blue staining. Mitochondrial function was detected via JC1 staining, mPTP opening assay, and immunofluorescence of cyt-c. Mitophagy was observed via western blots and immunofluorescence. Cell migration and proliferation were evaluated via Transwell and BrdU assay. Western blots were used to analyze the signaling pathways with JNK inhibitors or p53 siRNA. We found that Mst1 was down-regulated in CRC. Overexpression of Mst1 induced CRC apoptosis and impaired cell proliferation and migration. Functional studies have illustrated that recovery of Mst1 could activate JNK pathway which upregulated the p53 expression. The latter repressed Bnip3 transcription and activity, leading to the mitophagy arrest. The defective mitophagy impaired mitochondrial homeostasis, evoked cellular oxidative stress, and initiated the mitochondrial apoptosis. Meanwhile, bad-structured mitophagy also hindered the cancer proliferation via CyclinD/E. Moreover, Mst1-suppressed mitophagy was associated with CRC migration inhibition via regulation of CXCR4/7 expression. Collectively, our data described the comprehensive role of Mst1 in colorectal cancer stress response involving apoptosis, mobilization, and growth via handling mitophagy by JNK/p53/Bnip3 pathways.

Effects of melatonin on fatty liver disease: The role of NR4A1/DNA-PKcs/p53 pathway, mitochondrial fission, and mitophagy

Mitochondrial dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) through poorly defined mechanisms. Melatonin supplementation has been found to protect liver function in diabetes and obesity. Here, we intensively explored the role and mechanism of melatonin in the development of NAFLD. We demonstrated that the onset of diet-induced NAFLD greatly caused NR4A1 upregulation in hepatocytes, leading to the activation of DNA-PKcs and p53. On the one hand, p53 aided Drp1 migration in the mitochondria and consequently drove mitochondrial fission. On the other hand, p53 repressed Bnip3 transcription and expression, resulting in mitophagy arrest. The excessive fission and deficient mitophagy dramatically mediated mitochondrial dysfunction, including extensive mPTP opening, reduction in mitochondrial potential, oxidative stress, calcium overload, mitochondrial respiratory collapse, and ATP shortage. However, genetic deletion of NR4A1 or DNA-PKcs could definitively reverse NAFLD progression and the mitochondrial dysfunction. Similarly, melatonin supplementation could robustly reduce the damage to liver and mitochondrial structure and function in NAFLD. Mechanistically, melatonin halted fission but recovered mitophagy via blockade of NR4A1/DNA-PKcs/p53 pathway, finally improving mitochondrial and liver function in the setting of NAFLD. Our results identify NR4A1/DNA-PKcs/p53 pathway as the novel molecular mechanism underlying the pathogenesis of NAFLD via regulation of Drp1-mediated mitochondrial fission and Bnip3-related mitophagy. Meanwhile, we also confirm that melatonin has the ability to cut off the NR4A1/DNA-PKcs/p53 pathway, which confers a protective advantage to hepatocytes and mitochondria. The manipulation of NR4A1/DNA-PKcs/p53 pathway by melatonin highlights a new entry point for treating NAFLD.

QSKL protects against myocardial apoptosis on heart failure via PI3K/Akt-p53 signaling pathway

The ancient traditional Chinese medicine Qishenkeli (QSKL) is widely used in the treatment of heart failure (HF) in China. Previous studies have shown that QSKL has definite effects on HF. The purpose of this study is to identify the regulation of QSKL on apoptosis and clarify the underlying mechanism. An apoptosis model of H9C2 cells was induced by oxygen-glucose deprivation/recovery (OGD/R). An animal model of HF was induced by ligation of left anterior descending (LAD) coronary artery in rat. We found that QSKL reduced intracellular ROS generation, increased mitochondrial membrane potential and protected H9C2 cells against OGD/R-induced apoptosis. In vivo results showed that QSKL administration could improve cardiac functions, decrease fibrotic area, infarct size and apoptotic rate in HF model. QSKL regulated the expressions of key apoptotic molecules, including increasing Bcl-2/Bax ratio, reducing the expressions of P53, Bax and Cleaved-caspase-3. Interestingly, QSKL also regulated the phosphorylated expressions of PI3K and Akt without significantly affecting PTEN. Taken together, the protective and anti-apoptotic effects of QSKL could be mediated partly through modulating the PI3K/Akt-P53 apoptotic pathway.

Expanding perspectives on the significance of mitophagy in cancer

Mitophagy is a selective mode of autophagy in which mitochondria are specifically targeted for degradation at the autophagolysosome. Mitophagy is activated by stresses such as hypoxia, nutrient deprivation, DNA damage, inflammation and mitochondrial membrane depolarization and plays a role in maintaining mitochondrial integrity and function. Defects in mitophagy lead to mitochondrial dysfunction that can affect metabolic reprogramming in response to stress, alter cell fate determination and differentiation, which in turn affects disease incidence and etiology, including cancer. Here, we discuss how different mitophagy adaptors and modulators, including Parkin, BNIP3, BNIP3L, p62/SQSTM1 and OPTN, are regulated in response to physiological stresses and deregulated in cancers. Additionally, we explore how these different mitophagy control pathways coordinate with each other. Finally, we review new developments in understanding how mitophagy affects stemness, cell fate determination, inflammation and DNA damage responses that are relevant to understanding the role of mitophagy in cancer.

Hypoxia Induces Apoptosis through HIF-1α Signaling Pathway in Human Uterosacral Ligaments of Pelvic Organ Prolapse

The purpose of this study is to evaluate the expression of hypoxia-inducible factor-1α (HIF-1α) in women uterosacral ligament tissues with pelvic organ prolapse and women with normal uterine support structures and illuminate its relationship with apoptosis. Samples were collected from 38 women with pelvic organ prolapse and 31 age matched controls. The expression levels of HIF-1α and BNIP3 in the uterosacral ligaments were measured using immunohistochemistry, qRT-PCR, and Western blot. To assess apoptosis we performed TUNEL assay and Western blot analyses. Lastly, the short form of the Pelvic Floor Impact Questionnaire-7 (PFIQ-7) was used to evaluate prognosis of surgical patients and twenty patients finished the follow-up. The expressions of HIF-1α and BNIP3 in the uterosacral ligaments were significantly higher in patients with pelvic organ prolapse than in control group. Pearson's correlation test revealed significant positive correlations between HIF-1α and apoptosis index. Similarly, Western blot analysis showed the expression of proapoptosis proteins (Bax and Bad), Cytochrome-c, cleaved caspase-3, and caspase-9 in patients with pelvic organ prolapse was upregulated. The PFIQ-7 scores were higher in HIF-1α positive group than in the negative group. Hypoxia may contribute to the pathological process of pelvic organ prolapse by increasing apoptosis via activating HIF-1α signaling pathway.