Phosphorylation of ULK1 (hATG1) by AMP-activated protein kinase connects energy sensing to mitophagy

Role of Mitochondrial Dysfunctions in Neurodegenerative Disorders: Advances in Mitochondrial Biology

Mitochondria, essential organelles responsible for cellular energy production, emerge as a key factor in the pathogenesis of neurodegenerative disorders. This review explores advancements in mitochondrial biology studies that highlight the pivotal connection between mitochondrial dysfunctions and neurological conditions such as Alzheimer's, Parkinson's, Huntington's, ischemic stroke, and vascular dementia. Mitochondrial DNA mutations, impaired dynamics, and disruptions in the ETC contribute to compromised energy production and heightened oxidative stress. These factors, in turn, lead to neuronal damage and cell death. Recent research has unveiled potential therapeutic strategies targeting mitochondrial dysfunction, including mitochondria targeted therapies and antioxidants. Furthermore, the identification of reliable biomarkers for assessing mitochondrial dysfunction opens new avenues for early diagnosis and monitoring of disease progression. By delving into these advancements, this review underscores the significance of understanding mitochondrial biology in unraveling the mechanisms underlying neurodegenerative disorders. It lays the groundwork for developing targeted treatments to combat these devastating neurological conditions.

Regulation of autophagy: Insights into O-GlcNAc modification mechanisms

Autophagy is a "self-eating" biological process that degrades cytoplasmic contents to ensure cellular homeostasis. Its response to stimuli occurs in two stages: Within a few to several hours of exposure to a stress condition, autophagic flow rapidly increases, which is mediated by post-translational modification (PTM). Subsequently, the transcriptional program is activated and mediates the persistent autophagic response. O-linked β-N-acetylglucosamine (O-GlcNAc) modification is an inducible and dynamically cycling PTM; mounting evidence suggests that O-GlcNAc modification participates in the total autophagic process, including autophagy initiation, autophagosome formation, autophagosome-lysosome fusion, and transcriptional process. In this review, we summarize the current knowledge on the emerging role of O-GlcNAc modification in regulating autophagy-associated proteins and explain the different regulatory effects on autophagy exerted by O-GlcNAc modification.

Unconventional secretion of PARK7 requires lysosomal delivery via chaperone-mediated autophagy and specialized SNARE complex

PARK7/DJ-1, a redox-sensitive protein implicated in neurodegeneration, cancer, and inflammation, exhibits increased secretion under stress. We previously demonstrated that, as a leaderless protein, PARK7 relies on an unconventional autophagy pathway for stress-induced secretion. The current study delves deeper into the mechanisms governing PARK7 secretion under oxidative stress triggered by the neurotoxin 6-hydroxydopamine (6-OHDA). Here, we revealed that 6-OHDA-induced autophagic flux is critical for PARK7 secretion. Downregulation of syntaxin 17 (STX17), a SNARE protein crucial for autophagosome-lysosome fusion and cargo degradation, hindered PARK7 secretion. Likewise, impairing lysosomal function with bafilomycin A1 (BafA1) or chloroquine (CQ) diminished PARK7 release, highlighting the importance of functional lysosomes, potentially in the form of secretory autolysosomes, in PARK7 release. We also found that 6-OHDA appeared to promote the unfolding of PARK7, allowing its selective recognition by the chaperone HSPA8 via KFERQ-like motifs, leading to PARK7 translocation to the lysosomal membrane through LAMP2 via chaperone-mediated autophagy (CMA). Additionally, a dedicated SNARE complex comprising Qabc-SNAREs (STX3/4, VTI1B, and STX8) and R-SNARE SEC22B mediates the fusion of PARK7-containing autolysosomes with the plasma membrane, facilitating the extracellular release of PARK7. Hence, this study uncovers a mechanism where 6-OHDA-induced autophagic flux drives the unconventional secretion of PARK7, involving CMA for PARK7 translocation to lysosomes and specialized SNARE complexes for membrane fusion events.

Mitochondrial quality control: A promising target of traditional Chinese medicine in the treatment of cardiovascular disease

Cardiovascular disease remains the leading cause of death globally, and drugs for new targets are urgently needed. Mitochondria are the primary sources of cellular energy, play crucial roles in regulating cellular homeostasis, and are tightly associated with pathological processes in cardiovascular disease. In response to physiological signals and external stimuli in cardiovascular disease, mitochondrial quality control, which mainly includes mitophagy, mitochondrial dynamics, and mitochondrial biogenesis, is initiated to meet cellular requirements and maintain cellular homeostasis. Traditional Chinese Medicine (TCM) has been shown to have pharmacological effects on alleviating cardiac injury in various cardiovascular diseases, including myocardial ischemia/reperfusion, myocardial infarction, and heart failure, by regulating mitochondrial quality control. Recently, several molecular mechanisms of TCM in the treatment of cardiovascular disease have been elucidated. However, mitochondrial quality control by TCM for treating cardiovascular disease has not been investigated. In this review, we aim to decipher the pharmacological effects and molecular mechanisms of TCM in regulating mitochondrial quality in various cardiovascular diseases. We also present our perspectives regarding future research in this field.

Mitophagy is induced in human engineered heart tissue after simulated ischemia and reperfusion

The paradoxical exacerbation of cellular injury and death during reperfusion remains a problem in the treatment of myocardial infarction. Mitochondrial dysfunction plays a key role in the pathogenesis of myocardial ischemia and reperfusion injury. Dysfunctional mitochondria can be removed by mitophagy, culminating in their degradation within acidic lysosomes. Mitophagy is pivotal in maintaining cardiac homeostasis and emerges as a potential therapeutic target. Here, we employed beating human engineered heart tissue (EHT) to assess mitochondrial dysfunction and mitophagy during ischemia and reperfusion simulation. Our data indicate adverse ultrastructural changes in mitochondrial morphology and impairment of mitochondrial respiration. Furthermore, our pH-sensitive mitophagy reporter EHTs, generated by a CRISPR/Cas9 endogenous knock-in strategy, revealed induced mitophagy flux in EHTs after ischemia and reperfusion simulation. The induced flux required the activity of the protein kinase ULK1, a member of the core autophagy machinery. Our results demonstrate the applicability of the reporter EHTs for mitophagy assessment in a clinically relevant setting. Deciphering mitophagy in the human heart will facilitate development of novel therapeutic strategies.

GPNMB disrupts SNARE complex assembly to maintain bacterial proliferation within macrophages

Xenophagy plays a crucial role in restraining the growth of intracellular bacteria in macrophages. However, the machinery governing autophagosome‒lysosome fusion during bacterial infection remains incompletely understood. Here, we utilize leprosy, an ideal model for exploring the interactions between host defense mechanisms and bacterial infection. We highlight the glycoprotein nonmetastatic melanoma protein B (GPNMB), which is highly expressed in macrophages from lepromatous leprosy (L-Lep) patients and interferes with xenophagy during bacterial infection. Upon infection, GPNMB interacts with autophagosomal-localized STX17, leading to a reduced N-glycosylation level at N296 of GPNMB. This modification promotes the degradation of SNAP29, thus preventing the assembly of the STX17-SNAP29-VAMP8 SNARE complex. Consequently, the fusion of autophagosomes with lysosomes is disrupted, resulting in inhibited cellular autophagic flux. In addition to Mycobacterium leprae, GPNMB deficiency impairs the proliferation of various intracellular bacteria in human macrophages, suggesting a universal role of GPNMB in intracellular bacterial infection. Furthermore, compared with their counterparts, Gpnmbfl/fl Lyz2-Cre mice presented decreased Mycobacterium marinum amplification. Overall, our study reveals a previously unrecognized role of GPNMB in host antibacterial defense and provides insights into its regulatory mechanism in SNARE complex assembly.

Putrescine promotes maturation of oocytes from reproductively old mice via mitochondrial autophagy

RESEARCH QUESTION

Does putrescine (PUT) improve oocytes from reproductively old mice by promoting mitochondrial autophagy?

DESIGN

Germinal vesicle stage cumulus-oocyte complexes (COCs) were obtained from 9-month old female C57BL/6N mice and divided into control, PUT and difluoromethylornithine, inhibitor (DFMO) groups. These germinal vesicle COCs underwent mouse in-vitro maturation (IVM) culture to observe the extrusion of the first polar body in each group. Using JC-1, dichloro-dihydro-fluorescein diacetate fluorescent probes and a confocal microscope, the mitochondrial membrane potential integrity and reactive oxygen species levels were measured in metaphase II stage oocytes. The expression and cellular localization of the p53 protein were examined by immunofluorescence. Reverse transcription quantitative polymerase chain reaction was used to detect the activation of mitochondrial autophagy pathways. The potential mechanisms through which PUT improves oocytes from reproductively old mice were explored by single-cell transcriptomic analysis. Autophagosomes, autolysosomes and mitochondria in different groups were directly observed using transmission electron microscopy.

RESULTS

The addition of exogenous PUT can promote IVM of oocytes from reproductively old mice. It reduces oxidative stress by promoting the autophagy of damaged mitochondria, decreasing the levels of reactive oxygen species and increasing mitochondrial membrane potential. It affects the expression and subcellular localization of the p53 protein, and increases the expression of transcription factor EB, which may be the potential mechanism behind its promotion of autophagy.

CONCLUSION

The target and regulatory pathway of PUT in oocytes was clarified. Putrescine is an effective small molecule compound with significant potential for non-invasively improving the fertility of elderly women.

The ER protein CANX (calnexin)-mediated autophagy protects against alzheimer disease

Although the relationship between macroautophagy/autophagy and Alzheimer disease (AD) is widely studied, the underlying mechanisms are poorly understood, especially the regulatory role of the initiation signaling of autophagy on AD. Here, we find that the ER transmembrane protein CANX (calnexin) is a novel interaction partner of the autophagy-inducing kinase ULK1 and is required for ULK1 recruitment to the ER under basal or starved conditions. Loss of CANX results in the inactivity of ULK1 kinase and inhibits autophagy flux. In the brains of people with AD and APP-PSEN1 mice, the interaction of CANX and ULK1 declines. In mice, the lack of CANX in hippocampal neurons causes the accumulation of autophagy receptors and neuron damage, which affects the cognitive function of C57BL/6 mice. Conversely, overexpression of CANX in hippocampal neurons enhances autophagy flux and partially contributes to improving cognitive function of APP-PSEN1 mice, but not the CANX variant lacking the interaction domain with ULK1. These findings reveal a novel role of CANX in autophagy activity and cognitive function by cooperating with ULK1.Abbreviation: AD: Alzheimer disease; APEX: ascorbate peroxidase; APP: amyloid beta precursor protein; APP-PSEN1 mice: amyloid beta precursor protein-presenilin 1 transgenic mice; ATG: autophagy related; Aβ: amyloid-β; BiFC: bimolecular fluorescence complementation; CANX: calnexin; EBSS: Earle's balanced salt solution; EM: electron microscopy; IP: immunopurification; KO: knockout; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MWM: Morris water maze; PLA: proximity ligation assay; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; SQSTM1/p62, sequestosome 1.

Epimedii Folium and Ligustri Lucidi Fructus synergistically delay renal aging through AMPK/ULK1/Bcl2L13-mediated mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

The root of aging is attributed to kidney essence insufficiency and gradual loss of kidney function. The combination of Epimedii Folium and Ligustri Lucidi Fructus (ELL) is traditionally recognized to tonify kidney yin and yang and has significant efficacy in delaying aging and aging-related diseases, but little is known about the exact mechanism.

AIM OF THE STUDY

The research focuses on the mechanism of delaying renal aging by which ELL regulates mitophagy through serine/threonine kinase AMP-activated protein kinase (AMPK)/UNC-51- like autophagy activating kinase 1 (ULK1)/B-cell lymphoma-2-like protein 13 (Bcl2L13) in vivo.

MATERIALS AND METHODS

We employed a rat model of natural aging, using rats of different ages as dynamic controls, and a natural aging mouse model to evaluate the effects of ELL on delaying renal aging via AMPK/ULK1/Bcl2L13. The assessment included renal histopathology, oxidative stress, cell senescence, mitochondrial dynamics, mitophagy, and the AMPK/ULK1/Bcl2L13 signaling pathway. In the aging rat model, network pharmacology and proteomics were combined to dissect the renal aging process, and a Multilayer Perceptron (MLP) -artificial neural networks (ANN) model was used to evaluate the effects of ELL comprehensively. In the aging mouse model, the AMPK inhibitor dorsomorphin was applied to assess whether the AMPK signaling pathway was involved in ELL-induced mitophagy.

RESULTS

Compared with the young rats, the kidney exhibited signs of degenerative pathologies and increased oxidative stress in 17-month-old rats. A thorough analysis identified the mitochondrial protein Bcl2L13 as a crucial biomarker associated with renal aging. The AMPK/ULK1/Bcl2L13 pathway significantly regulated mitochondrial function and mitophagy, which were potential mechanisms underlying renal aging. In contrast to aged rats, the renal pathological changes and cell senescence in rats treated with ELL were significantly mitigated, the antioxidant capacity, mitochondrial dynamics, and mitophagy were improved, and the expression of AMPK/ULK1/Bcl2L13 was upregulated. After the application of AMPK inhibitor dorsomorphin, the effects of ELL were reversed. It appears that ELL modulates the AMPK/ULK1/Bcl2L13 signaling pathway, and upregulates mitophagy to potentially decelerate renal aging.

CONCLUSIONS

The findings indicate that aging kidneys display mitochondrial dysfunction, disorganization of mitochondria, and a decrease in mitophagy. Concurrently, ELL significantly regulates mitochondrial dynamics and mitophagy via AMPK/ULK1/Bcl2L13. This regulation helps mitigate mitochondrial dysfunction, suggesting ELL as a promising herbal remedy for delaying renal aging and age-related kidney diseases.

Premature skeletal muscle aging in VPS13A deficiency relates to impaired autophagy

VPS13A disease (chorea-acanthocytosis), is an ultra-rare autosomal recessive neurodegenerative disorder caused by mutations of the VPS13A gene encoding Vps13A. Increased serum levels of the muscle isoform of creatine kinase associated with often asymptomatic muscle pathology are among the poorly understood early clinical manifestations of VPS13A disease. Here, we carried out an integrated analysis of skeletal muscle from Vps13a-/- mice and from VPS13A disease patient muscle biopsies. The absence of Vps13A impaired autophagy, resulting in pathologic metabolic remodeling characterized by cellular energy depletion, increased protein/lipid oxidation and a hyperactivated unfolded protein response. This was associated with defects in myofibril stability and the myofibrillar regulatory proteome, with accumulation of the myocyte senescence marker, NCAM1. In Vps13a-/- mice, the impairment of autophagy was further supported by the lacking effect of starvation alone or in combination with colchicine on autophagy markers. As a proof of concept, we showed that rapamycin treatment rescued the accumulation of terminal phase autophagy markers LAMP1 and p62 as well as NCAM1, supporting a connection between impaired autophagy and accelerated aging in the absence of VPS13A. The premature senescence was also corroborated by local activation of pro-inflammatory NF-kB-related pathways in both Vps13a-/- mice and patients with VPS13A disease. Our data link for the first time impaired autophagy and inflammaging with muscle dysfunction in the absence of VPS13A. The biological relevance of our mouse findings, supported by human muscle biopsy data, shed new light on the role of VPS13A in muscle homeostasis.

Nano-zinc oxide (nZnO) targets the AMPK-ULK1 pathway to promote bone regeneration

BACKGROUND

Nano-zinc oxide (nZnO) has attracted significant attention in bone tissue engineering due to its antibacterial properties, anti-inflammatory effects, biocompatibility, and chemical stability. Although numerous studies have demonstrated the enhancement of osteogenic differentiation by nZnO-modified tissue engineering materials, the underlying mechanisms remain poorly characterized.

METHODS

This study aimed to identify the molecular mechanisms how nZnO promoted osteogenic differentiation and bone regeneration using transcriptome analysis, drug intervention, and shRNA knockdown techniques, etc. First, the study evaluated the in vivo effects of gelatin methacryloyl (GelMA) containing nZnO on bone regeneration using a mouse calvarial defect model. The impact of nZnO exposure on the osteogenic differentiation of mesenchymal stem cells (MSCs) was then assessed. The combined treatment of nZnO and MSCs in GelMA for bone regeneration was assessed in the mouse calvarial defect model thereafter.

RESULTS

nZnO induced osteoblastic differentiation to promote bone regeneration. nZnO activated the AMP-dependent protein kinase (AMPK)-ULK1 signals to stimulate autophagosomes formation and facilitate autophagy flow, which was the essential pathway to induce osteogenic differentiation. The combined treatment of MSCs and nZnO significantly enhanced bone regeneration in calvarial defect mice. Conversely, AMPK inhibitor Compound C (C.C) reversed the effects on autophagy flow and osteogenic potentiality induced by nZnO.

CONCLUSIONS

These results highlight that nZnO can regulate bone regeneration by activating autophagy through the AMPK/ULK1 signaling pathway, which may provide a novel therapeutic strategy for addressing bone defects using nZnO.

TTK promotes mitophagy by regulating ULK1 phosphorylation and pre-mRNA splicing to inhibit mitochondrial apoptosis in bladder cancer

Bladder cancer (BC) remains a major global health challenge, with poor prognosis and limited therapeutic options in advanced stages. TTK protein kinase (TTK), a serine/threonine kinase, has been implicated in the progression of various cancers, but its role in BC has not been fully elucidated. In this study, we show that TTK is significantly upregulated in BC tissues and cell lines, correlating with poor patient prognosis. Functional assays revealed that TTK promotes proliferation and inhibits apoptosis of BC cells. Mechanistically, TTK enhances mitophagy by directly phosphorylating ULK1 at Ser477, thereby activating the ULK1/FUNDC1-mediated mitophagy pathway. TTK knockdown disrupts mitophagy, leading to impaired clearance of damaged mitochondria, excessive accumulation of mitochondrial reactive oxygen species (mtROS), and activation of mitochondrial apoptosis. Furthermore, TTK phosphorylates SRSF3 at Ser108, preventing ULK1 exon 5 skipping and maintaining ULK1 mRNA stability. These findings show that TTK plays a key role in maintaining mitophagy in BC cells. Targeting TTK could offer a promising new approach for BC treatment by disrupting mitophagy and inducing mitochondrial apoptosis.

AMPK in Intestinal Health and Disease: A Multifaceted Therapeutic Target for Metabolic and Inflammatory Disorders

The intestines play essential roles in nutrient absorption and immune function and help maintain a protective barrier. Disruptions to its function can result in various diseases, including metabolic disorders, inflammation, and cancer. As a key regulator of cellular energy levels, 5'-adenosine monophosphate-activated protein kinase (AMPK) is essential for intestinal health. Beyond its established metabolic role, emerging evidence suggests that AMPK exerts profound effects on intestinal cell physiology, influencing cell proliferation and differentiation, inflammation, autophagy, barrier integrity, and smooth muscle contractility. Here, we explore the structure and regulation of AMPK, as well as its diverse roles in intestinal diseases and potential as a therapeutic target. Our findings reveal that AMPK is a multifaceted regulator of intestinal health, modulating various cellular processes and intestinal diseases. It plays a dual role in cancer, acting as both a tumor suppressor and promoter, and it regulates inflammatory pathways, autophagy, tight junction formation, and smooth muscle contractility. Both natural and synthetic AMPK activators offer promise as therapeutic agents. This review of AMPK's mechanisms and activators offers valuable insights for developing novel therapies for intestinal disorders. Further research is needed to fully define AMPK's roles and therapeutic potential.

Energy Metabolism and Brain Aging: Strategies to Delay Neuronal Degeneration

Aging is characterized by a gradual decline in physiological functions, with brain aging being a major risk factor for numerous neurodegenerative diseases. Given the brain's high energy demands, maintaining an adequate ATP supply is crucial for its proper function. However, with advancing age, mitochondria dysfunction and a deteriorating energy metabolism lead to reduced overall energy production and impaired mitochondrial quality control (MQC). As a result, promoting healthy aging has become a key focus in contemporary research. This review examines the relationship between energy metabolism and brain aging, highlighting the connection between MQC and energy metabolism, and proposes strategies to delay brain aging by targeting energy metabolism.

Lysosomes and LAMPs as Autophagy Drivers of Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is among the most malignant pathologies worldwide. A major factor contributing to the poor prognosis of neoplastic diseases is the development of drug resistance. It significantly reduces the utility of most therapeutic protocols and necessitates the search for novel biomarkers and treatment strategies to combat cancer. An evolutionarily conserved catabolic mechanism, autophagy maintains nutrient recycling and metabolic adaptation and is also closely related to carcinogenesis, playing a dual role. Autophagy inhibition can limit the growth of tumors and improve the response to cancer therapeutics. Lysosomes, key players in autophagy, are also considered promising targets for anticancer treatment. There are still insufficient data on the role of poorly studied glycoproteins related to autophagy, such as the lysosome-associated membrane glycoproteins (LAMPs). They can act as multifunctional molecules involved in a multitude of processes like autophagy and cancer development. In the current review, we summarize the recent data on the double-faceted role of autophagy in cancer with a focus on drug resistance in CRC and on the roles of lysosomes and LAMPs in these interconnected processes. Several lysosomotropic drugs are discussed as options to overcome cancer cell chemoresistance. The complex networks that underline defined autophagic pathways in the context of CRC carcinogenesis and the role of autophagy, especially of LAMPs as drivers of drug resistance, are outlined.

The role of autophagy in cancer: from molecular mechanism to therapeutic window

Autophagy is a cellular degradation process that plays a crucial role in maintaining metabolic homeostasis under conditions of stress or nutrient deprivation. This process involves sequestering, breaking down, and recycling intracellular components such as proteins, organelles, and cytoplasmic materials. Autophagy also serves as a mechanism for eliminating pathogens and engulfing apoptotic cells. In the absence of stress, baseline autophagy activity is essential for degrading damaged cellular components and recycling nutrients to maintain cellular vitality. The relationship between autophagy and cancer is well-established; however, the biphasic nature of autophagy, acting as either a tumor growth inhibitor or promoter, has raised concerns regarding the regulation of tumorigenesis without inadvertently activating harmful aspects of autophagy. Consequently, elucidating the mechanisms by which autophagy contributes to cancer pathogenesis and the factors determining its pro- or anti-tumor effects is vital for devising effective therapeutic strategies. Furthermore, precision medicine approaches that tailor interventions to individual patients may enhance the efficacy of autophagy-related cancer treatments. To this end, interventions aimed at modulating the fate of tumor cells by controlling or inducing autophagy substrates necessitate meticulous monitoring of these mediators' functions within the tumor microenvironment to make informed decisions regarding their activation or inactivation. This review provides an updated perspective on the roles of autophagy in cancer, and discusses the potential challenges associated with autophagy-related cancer treatment. The article also highlights currently available strategies and identifies questions that require further investigation in the future.

Knockdown of SMYD3 by RNA Interference Regulates the Expression of Autophagy-Related Proteins and Inhibits Bone Formation in Fluoride-Exposed Osteoblasts

This study aimed to explore the role of histone methyltransferase SET and MYND domain containing 3 (SMYD3) in bone metabolism of osteoblasts exposed to fluoride. The levels of urine fluoride, BALP, and OC and the mRNA expression of SMYD3 were determined in patients with skeletal fluorosis and non-fluoride-exposed people on informed consent. The expression of SMYD3 protein, OC contents, and BALP activities were detected in human osteoblast-like MG63 cells and rat primary osteoblasts treated with sodium fluoride (NaF) for 48 h. The autophagosomes were observed by transmission electron microscopy. Then, we knocked down SMYD3 to confirm whether it was involved in the regulation of bone formation and related to autophagy and Wnt/β-catenin pathway. We observed that OC and BALP levels in patients with skeletal fluorosis significantly increased, while the mRNA expression of SMYD3 significantly decreased in the skeletal fluorosis groups. In vitro, the OC contents, BALP activities, and expression of SMYD3 significantly increased, and many autophagosomes were observed in NaF treated osteoblasts. The downregulation of SMYD3 significantly inhibited OC contents, BALP activities, and expression of autophagy-related proteins, but with no significant changes in the Wnt/β-catenin pathway. Our results demonstrated that fluoride exposure with coal-burning pollution caused orthopedic injuries and abnormalities in the levels of OC and BALP and hindered normal bone metabolism. Silencing the SMYD3 gene could significantly reduce OC and BALP levels via inhibiting the increase in autophagy induced by fluoride.

RNA-seq analysis of mitochondria-related genes regulated by AMPK in the human trophoblast cell line BeWo

BACKGROUND

How AMP activated protein kinase (AMPK) signaling regulates mitochondrial functions and mitophagy in human trophoblast cells remains unclear. This study was designed to investigate potential players mediating the regulation of AMPK on mitochondrial functions and mitophagy by next generation RNA-seq.

METHODS

We compared ATP production in protein kinase AMP-activated catalytic subunit alpha 1/2 (PRKAA1/2) knockdown (AKD) and control BeWo cells using the Seahorse real-time ATP rate test, then analyzed gene expression profiling by RNA-seq. Differentially expressed genes (DEG) were examined by Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Then protein-protein interactions (PPI) among mitochondria related genes were further analyzed using Metascape and Ingenuity Pathway Analysis (IPA) software.

RESULTS

Both mitochondrial and glycolytic ATP production in AKD cells were lower than in the control BeWo cells (CT), with a greater reduction of mitochondrial ATP production. A total of 1092 DEGs were identified, with 405 upregulated and 687 downregulated. GO analysis identified 60 genes associated with the term 'mitochondrion' in the cellular component domain. PPI analysis identified three clusters of mitochondria related genes, including aldo-keto reductase family 1 member B10 and B15 (AKR1B10, AKR1B15), alanyl-tRNA synthetase 1 (AARS1), mitochondrial ribosomal protein S6 (MRPS6), mitochondrial calcium uniporter dominant negative subunit beta (MCUB) and dihydrolipoamide branched chain transacylase E2 (DBT).

CONCLUSIONS

In summary, this study identified multiple mitochondria related genes regulated by AMPK in BeWo cells, and among them, three clusters of genes may potentially contribute to altered mitochondrial functions in response to reduced AMPK signaling.

Thermogenesis and Energy Metabolism in Brown Adipose Tissue in Animals Experiencing Cold Stress

Cold exposure is a regulatory biological functions in animals. The interaction of thermogenesis and energy metabolism in brown adipose tissue (BAT) is important for metabolic regulation in cold stress. Brown adipocytes (BAs) produce uncoupling protein 1 (UCP1) in mitochondria, activating non-shivering thermogenesis (NST) by uncoupling fuel combustion from ATP production in response to cold stimuli. To elucidate the mechanisms underlying thermogenesis and energy metabolism in BAT under cold stress, we explored how cold exposure triggers the activation of BAT thermogenesis and regulates overall energy metabolism. First, we briefly outline the precursor composition and function of BA. Second, we explore the roles of the cAMP- protein kinase A (PKA) and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways in thermogenesis and energy metabolism in BA during cold stress. Then, we analyze the mechanism by which BA regulates mitochondria homeostasis and energy balance during cold stress. This research reveals potential therapeutic targets, such as PKA, AMPK, UCP1 and PGC-1α, which can be used to develop innovative strategies for treating metabolic diseases. Furthermore, it provides theoretical support for optimizing cold stress response strategies, including the pharmacological activation of BAT and the genetic modulation of thermogenic pathways, to improve energy homeostasis in livestock.

The Role of Mitophagy in Cardiac Metabolic Remodeling of Heart Failure: Insights of Molecular Mechanisms and Therapeutic Prospects

Heart failure (HF) treatment remains one of the major challenges in cardiovascular disease management, and its pathogenesis requires further exploration. Cardiac metabolic remodeling is of great significance as a key pathological process in the progression of HF. The complex alterations of metabolic substrates and associated enzymes in mitochondria create a vicious cycle in HF. These changes lead to increased reactive oxygen species, altered mitochondrial Ca2+ handling, and the accumulation of fatty acids, contributing to impaired mitochondrial function. In this context, mitophagy plays a significant role in clearing damaged mitochondria, thereby maintaining mitochondrial function and preserving cardiac function by modulating metabolic remodeling in HF. This article aims to explore the role of mitophagy in cardiac metabolic remodeling in HF, especially in obesity cardiomyopathy, diabetic cardiomyopathy, and excessive afterload-induced heart failure, thoroughly analyze its molecular mechanisms, and review the therapeutic strategies and prospects based on the regulation of mitophagy.

AMPK-dependent Parkin activation suppresses macrophage antigen presentation to promote tumor progression

The constrained cross-talk between myeloid cells and T cells in the tumor immune microenvironment (TIME) restricts cancer immunotherapy efficacy, whereas the underlying mechanism remains elusive. Parkin, an E3 ubiquitin ligase renowned for mitochondrial quality control, has emerged as a regulator of immune response. Here, we show that both systemic and macrophage-specific ablations of Parkin in mice lead to attenuated tumor progression and prolonged mouse survival. By single-cell RNA-seq and flow cytometry, we demonstrate that Parkin deficiency reshapes the TIME through activating both innate and adaptive immunities to control tumor progression and recurrence. Mechanistically, Parkin activation by AMP-activated protein kinase rather than PTEN-induced kinase 1 mediated major histocompatibility complex I down-regulation on macrophages via Autophagy related 5-dependent autophagy. Furthermore, Parkin deletion synergizes with immune checkpoint blockade treatment and Park2-/- signature aids in predicting the prognosis of patients with solid tumor. Our findings uncover Parkin's involvement in suppressing macrophage antigen presentation for coordinating the cross-talk between macrophages and T cells.

Targeting PI3K inhibitor resistance in breast cancer with metabolic drugs

Activating PIK3CA mutations, present in up to 40% of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (Her2-) breast cancer (BC) patients, can be effectively targeted with the alpha isoform-specific PI3K inhibitor Alpelisib. This treatment significantly improves outcomes for HR+, Her2-, and PIK3CA-mutated metastatic BC patients. However, acquired resistance, often due to aberrant activation of the mTOR complex 1 (mTORC1) pathway, remains a significant clinical challenge. Our study, using in vitro and orthotopic xenograft mouse models, demonstrates that constitutively active mTORC1 signaling renders PI3K inhibitor-resistant BC exquisitely sensitive to various drugs targeting cancer metabolism. Mechanistically, mTORC1 suppresses the induction of autophagy during metabolic perturbation, leading to energy stress, a critical depletion of aspartate, and ultimately cell death. Supporting this mechanism, BC cells with CRISPR/Cas9-engineered knockouts of canonical autophagy genes showed similar vulnerability to metabolically active drugs. In BC patients, high mTORC1 activity, indicated by 4E-BP1T37/46 phosphorylation, correlated with p62 accumulation, a sign of impaired autophagy. Together, these markers predicted poor overall survival in multiple BC subgroups. Our findings reveal that aberrant mTORC1 signaling, a common cause of PI3K inhibitor resistance in BC, creates a druggable metabolic vulnerability by suppressing autophagy. Additionally, the combination of 4E-BP1T37/46 phosphorylation and p62 accumulation serves as a biomarker for poor overall survival, suggesting their potential utility in identifying BC patients who may benefit from metabolic therapies.

Metformin Protects Human Induced Pluripotent Stem Cell (hiPSC)-Derived Neurons from Oxidative Damage Through Antioxidant Mechanisms

The antidiabetic drug metformin possesses antioxidant and cell protective effects including in neuronal cells, suggesting its potential use for treating neurodegenerative diseases. This study aimed to assess metformin's effects on viability and antioxidant activity in human-induced pluripotent stem cell (hiPSC)-derived neurons under varying concentrations and stress conditions. Six lines of hiPSC-derived neuronal progenitors derived from healthy human iPSCs were treated with metformin (1-500 µM) on day 18 of differentiation. For mature neurons (day 30), three concentrations (10 µM, 50 µM, and 100 µM) were used to assess cytotoxicity. MG132 proteasomal inhibitor and sodium arsenite (NaArs) were used to investigate oxidative stress, and 50 µM of metformin was tested for its protective effects against oxidative stress in hiPSC-derived neurons. Metformin treatment did not affect cell viability, neuronal differentiation, or trigger reactive oxygen species (ROS) generation in healthy hiPSC-derived motor neurons. Additionally, mitochondrial membrane potential (MMP) loss was not observed at 50 µM metformin. Metformin effectively protected neurons from stress agents and elevated the expression of antioxidant genes when treated with MG132. However, an interplay between MG132 and metformin resulted in lower expression of Nrf2 and NQO1 compared to the MG132 group alone, indicating reduced JC-1 aggregate levels due to MG132 proteasomal inhibition. Metformin upregulated antioxidant genes in hiPSC-derived neurons under stress conditions and protected the cells from oxidative damage.

AMPK and CAMKK activation participate in early events of Toxoplasma gondii-triggered NET formation in bovine polymorphonuclear neutrophils

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that infects humans, eventually causing severe diseases like prenatal or ocular toxoplasmosis. T. gondii also infects cattle but rarely induces clinical signs in this intermediate host type. So far, the innate immune mechanisms behind the potential resistance of bovines to clinical T. gondii infections remain unclear. Here, we present evidence on sustained activation of bovine polymorphonuclear neutrophils PMN by T. gondii tachyzoites, which is linked to a rise in cytoplasmic calcium concentrations, an enhancement of calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK) and AMP-activated protein kinase (AMPK). NETosis is a specific form of programmed cell death, characterized by the release chromatin from the nucleus to the extracellular space resulting in formation of neutrophil extracellular traps (NETs). NETs can kill and entrap pathogens. In our experiments, NETosis was triggered by T. gondii, and this effector mechanism was enhanced by pre-treatments with the AMPK activator AICAR. Moreover, tachyzoite-mediated bovine neutrophil DNA release depended on MAPK- and store operated calcium entry- (SOCE) pathways since it was diminished by the inhibitors UO126 and 2-APB, respectively. Overall, we here provide new insights into early polymorphonuclear neutrophils responses against T. gondii for the bovine system.

Characterization and neurotherapeutic evaluation of venom polypeptides identified from Vespa magnifica: The role of Mastoparan-M in Parkinson's disease intervention

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a common neurodegenerative disorder in the elderly, characterized by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy bodies. Hufeng Jiu from Vespa magnifica Smith, a traditional remedy used by the Chinese Jingpo minority, is documented in the Pharmacopoeia of China (2020) for treating rheumatic arthritis. Notably, recent research suggests that components of wasp venom (WV) from Vespa magnifica Smith, particularly polypeptides such as Mastoparan-M (Mast-M) and Vespakinin-M, may have potential therapeutic effects for neurological disorders. However, the specific polypeptide components of WV and their therapeutic effects on PD models remain insufficiently understood.

AIM OF THE STUDY

This study aims to characterize the neuroactive polypeptides in Vespa magnifica Smith venom and investigate the therapeutic potential of Mast-M for PD.

MATERIALS AND METHODS

Neuroactive polypeptides in WV were identified using LC/MS, and Mast-M derived from venom of Vespa magnifica Smith was verified with HPLC. The neuroprotective effects of WV and its peptides were assessed using the CCK-8 assay in 1-methyl-4- phenylpyridinium (MPP+)-induced SH-SY5Y human neuroblastoma cells. Mast-M was identified as a potent antagonist against MPP+-induced neurotoxicity. The toxicity, hemolytic activity, and blood-brain-barrier (BBB) permeability of Mast-M were evaluated in mice, and its therapeutic effects were assessed in an MPTP-induced PD mouse model, focusing on motor function and tyrosine hydroxylase (TH) levels. Additionally, Mast-M's impact on mitochondrial membrane potential (MMP), autophagy, and the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signling pathway was investigated.

RESULTS

A total of 1007 peptides were identified in the WV, including 187 UniProtKB unreviewed, with 185 predicted to be BBB-permeability. Our results show that Mast-M exhibits a time-dependent distribution in mice, initially localizing in the peritoneal region and subsequently accumulating in the brain, liver, and kidney. Cellular uptake studies reveal that Mast-M penetrates cell membranes and accumulates intracellularly over time. In the MPP+-induced neurotoxicity model using SH-SY5Y cells, Mast-M significantly enhances cell viability and MMP. In vivo safety assessments indicate that Mast-M is well-tolerated at doses up to 100 μg/kg, with no significant toxicological effects observed. However, higher doses induce hepatic distress, necessitating dose optimization. Hemolysis was absent at concentrations ≤37 μg/mL, with an EC50 for hemolytic activity of 197 μg/mL. In MPTP-induced PD models, Mast-M partially ameliorates motor deficits and preserves TH expression in dopaminergic neurons, supporting its neuroprotective role. Mechanistically, Mast-M activates autophagic pathways, as evidenced by the upregulation of autophagy-related protein LC3 in MPP+-challenged SH-SY5Y cells. Furthermore, Mast-M promotes mitophagy and mitochondrial biogenesis, modulating the AMPK/mTOR signaling axis to facilitate mitochondrial turnover.

CONCLUSION

Mast-M emerges as a promising therapeutic candidate for PD, capable of crossing the BBB, enhancing autophagy, and providing neuroprotection in PD models. Further studies are warranted to optimize dosing and elucidate its full therapeutic potential.

AMPK activation by hepatitis E virus infection inhibits viral replication through attenuation of autophagosomes and promotion of innate immunity

Hepatitis E virus (HEV) infection is generally asymptomatic or leads to acute and self-limiting hepatitis. The mechanisms orchestrating such an infection course remain to be elucidated. AMP-activated protein kinase (AMPK) is a pivotal cellular sensor for maintaining metabolic homeostasis. Here, we show that AMPK is activated in response to HEV infection and is associated with mitochondrial damage and ATP deficiency. AMPK activation, in turn, inhibits HEV replication. Mechanistic studies reveal that AMPK activation triggers the expression of interferon (IFN)-stimulated genes that possess antiviral properties. In parallel, AMPK inhibits autophagosome accumulation to exert antiviral effects. Interestingly, AMPK activation also suppresses the inflammatory response triggered by HEV infection. Consistently, AMPK activation simultaneously exerts anti-inflammatory and antiviral effects in a coculture system of HEV-infected liver cells with macrophages. These findings pave the way for the development of AMPK-targeted therapeutics to treat hepatitis E.

Research progress on AMPK in the pathogenesis and treatment of MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD; formerly known as non-alcoholic fatty liver disease, NAFLD) has become one of the most prevalent chronic liver diseases worldwide, with its incidence continuously rising alongside the epidemic of metabolic disorders. AMP-activated protein kinase (AMPK), as a key regulator of cellular energy metabolism, influences multiple pathological processes associated with MASLD. This review systematically summarizes the regulatory roles of AMPK in lipid metabolism, inflammatory response, cell apoptosis, and fibrosis. Additionally, it discusses the latest developments of AMPK activators from preclinical to clinical studies, while analyzing the major challenges currently faced and potential strategies for resolution. A deeper understanding of AMPK regulatory mechanisms will contribute to the development of more effective therapeutic approaches for MASLD.

Multi-omics study on autophagic dysfunction molecular network in the pathogenesis of rheumatoid arthritis

BACKGROUND

Autophagy is associated with the development of rheumatoid arthritis (RA), but its genetic pathological mechanisms remain incompletely understood. In this study, we employed summary-data-based Mendelian randomization (SMR) and co-localization analysis to systematically investigate the relationship between autophagy-related genes and RA.

METHODS

We obtained summary data on blood methylation (mQTL), gene expression (eQTL), and protein abundance (pQTL) from respective quantitative trait locus (QTL) studies. Genetic association data for RA were primarily derived from the FinnGen database, with validation performed using the UK Biobank (UKB) and GWAS Catalog databases. SMR analysis was conducted to evaluate the association between molecular characteristics of autophagy-related genes and RA. Subsequently, co-localization analysis was performed to determine whether the identified signals share the same causal genetic variants.

RESULTS

After integrating mQTL-eQTL multi-omics data, we identified two key autophagy genes, BCL2L1 and RAF1, which may have a causal relationship with RA. Significant associations were found for BCL2L1 (cg12873919, cg13989999) and RAF1 (cg26432171) in the SMR analysis of autophagy-related mQTL, eQTL, and GWAS data (p SMR < 0.05). In the integrated mQTL-eQTL SMR analysis, cg12873919 (p SMR = 1.40E-07, OR = 0.82, 95% CI [0.76-0.88]), cg13989999 (p SMR = 1.43E-06, OR = 0.78, 95% CI [0.71-0.87]), and cg26432171 (p SMR = 9.18E-09, OR = 1.83, 95% CI [1.49-2.25]) were all significantly validated. Methylation of cg12873919 and cg13989999 in BCL2L1 was associated with increased BCL2L1 expression, consistent with their negative impact on RA risk. Conversely, the cg26432171 site in RAF1 showed a positive correlation between gene methylation and expression. In the eQTL-GWAS SMR analysis, MAPK3 expression (p SMR = 7.24E-05, OR = 0.91, 95% CI [0.87-0.95]) was negatively correlated with RA risk, a finding supported by co-localization analysis (PPH4 > 0.5), suggesting that this gene may inhibit RA pathogenesis by regulating the autophagy process. Furthermore, protein level analysis also supported the protective role of MAPK3 (p SMR = 7.53E-05, OR = 0.89, 95% CI [0.84-0.94]).

CONCLUSION

We identified that autophagy-related genes BCL2L1 and RAF1 may be associated with RA risk, providing strong evidence from multi-omics data. This study identifies autophagy genes related to RA, potentially offering new insights into the pathogenesis of RA.

Recent advances in the clinical spectrum and pathomechanisms associated with X-linked myopathy with excessive autophagy and other VMA21-related disorders

X-linked myopathy with excessive autophagy (XMEA) is a rare neuromuscular disorder caused by mutations in the VMA21 gene, encoding a chaperone protein present in the endoplasmic reticulum (ER). In yeast and human, VMA21 has been shown to chaperone the assembly of the vacuolar (v)-ATPase proton pump required for the acidification of lysosomes and other organelles. In line with this, VMA21 deficiency in XMEA impairs autophagic degradation steps, which would be key in XMEA pathogenesis. Recent years have witnessed a surge of interest in VMA21, with the identification of novel mutations causing a congenital disorder of glycosylation (CDG) with liver affection, and its potent implication in cancer predisposition. With this, VMA21 deficiency has been further linked to defective glycosylation, lipid metabolism dysregulation and ER stress. Moreover, the identification of two VMA21 isoforms, namely VMA21-101 and VMA21-120, has opened novel avenues regarding the pathomechanisms leading to XMEA and VMA21-CDG. In this review, we discuss recent advances on the clinical spectrum associated with VMA21 deficiency and on the pathophysiological roles of VMA21.

The Biological Rationale for Integrating Intrinsic Capacity Into Frailty Models

The assessment and management of two function-centered clinical care models, frailty and intrinsic capacity decline have been proposed to achieve healthy aging. To implement these two care models, several different guidelines have been advocated by different health organizations, which has resulted in confusion and cost-ineffective results in healthcare practice. Although there are various operational definitions and screening tools of frailty, the most accepted operational definitions are based on the recognition of frailty phenotypes or deficit accumulation-based frailty indexes. Intrinsic capacity, referred to as the total physical and mental capacities for individual to undertake daily tasks in everyday life, is another care model, including five domains. Similar or identical instruments have been used to assess frailty and intrinsic capacity. In the present narrative review, we outlined the biological rationale for integrating intrinsic capacity into frailty models and highlighted the hierarchical and energy-dependent order of the intrinsic capacity domains. The vitality domain or energy metabolism-related capacity, is the highest order dimension and the basis of other intrinsic capacity domains. Vitality vulnerability manifests as a pre-frailty status in function-centered healthy aging. We provided a conceptual framework of frailty phenotypes and frailty indexes based on the hierarchical and energy-dependent order of the intrinsic capacity domains, particularly vitality capacity. To facilitate the clinical translation of the framework, some potential energy metabolism-related biomarkers have also been proposed as critical components for assessing and screening vitality capacity in older age. The integrating framework not only provides testable theoretical hypotheses, particularly about vitality as a foundational element in aging, but could serve as a starting point for further research to unravel the mechanisms of frailty. It also improves cost-effectiveness for optimizing aging interventions in clinical healthcare and public health policies of healthy aging.

Interspecies differences in mitochondria: Implications for cardiac and vascular translational research

Mitochondria are essential organelles that regulate cellular energy metabolism, redox balance, and signaling pathways related to proliferation, aging and survival. So far, significant interspecies differences exist in mitochondrial structure, function, and dynamics, which have critical implications for cardiovascular physiology and pharmacology. This review explores the main differences in mitochondrial properties across species of animals that are commonly used for translational research, emphasizing their cardiac and vascular relevance. By addressing key interspecies differences, including mitochondrial DNA (mtDNA) variation, bioenergetic profile, oxidative stress response, epigenetic regulation, mitochondrial biogenesis, and adaptive mechanisms, we aim to provide insights into the challenges and opportunities in translating preclinical findings to clinical applications. Understanding these interspecies differences is essential for optimizing the design and interpretation of preclinical studies and for developing effective mitochondrial-targeted therapies.

Targeting intracellular autophagic process for the treatment of post-stroke ischemia/reperfusion injury

Cerebral ischemia/reperfusion (I/R) injury is an important pathophysiological condition of ischemic stroke that involves a variety of physiological and pathological cell death pathways, including autophagy, apoptosis, necroptosis, and phagoptosis, among which autophagy is the most studied. We have reviewed studies published in the past 5 years regarding the association between autophagy and cerebral I/R injury. To the best of our knowledge, this is the first review article summarizing potential candidates targeting autophagic pathways in the treatment of I/R injury post ischemic stroke. The findings of this review may help to better understand the pathogenesis and mechanisms of I/R events and bridge the gap between basic and translational research that may lead to the development of novel therapeutic approaches for I/R injury.

Pathological Mechanisms of Irradiation-Induced Neurological Deficits in the Developing Brain

Cranial irradiation or radiotherapy (CRT) is one of the essential therapeutic modalities for central nervous system (CNS) tumors, and its efficacy is well known. Nevertheless, CRT is also associated with brain damages such as focal cerebral necrosis, neuroinflammation, cerebral microvascular anomalies, neurocognitive dysfunction, and hormone deficiencies in children. Children's brains are much more sensitive to CRT compared to the adult's brains. Thus, children's brains are also more likely to develop long-term CRT complication, which severely lessens their long-term quality of life after treatment. CRT to the juvenile rat led to a retardation of growth of the cerebellum; both the gray and white matter and neurogenic regions like the subventricular zone and the dentate gyrus in the hippocampus were predominantly vulnerable to CRT. Also, CRT-induced cognitive changes typically manifested as deficits in hippocampal-related functions of learning as well as memory, such as spatial information processing. Fractionated CRT-stimulated cognitive decline and hormone deficiencies were precisely associated with augmented neuronal cell death, blockade of neurogenesis, and stimulation of astrocytes and microglia. Thus, the aim of this review is to highlight the pathological mechanism of CRT-induced neurological deficits in the developing brain.

Renal mitochondria response to sepsis: a sequential biopsy evaluation of experimental porcine model

BACKGROUND

The pathophysiology of sepsis-induced acute kidney injury remains elusive. Although mitochondrial dysfunction is often perceived as the main culprit, data from preclinical models yielded conflicting results so far. The aim of this study was to assess the immune-metabolic background of sepsis-associated renal dysfunction using sequential biopsy approach with mitochondria function evaluation in a large clinically relevant porcine models mimicking two different paces and severity of sepsis and couple this approach with traditional parameters of renal physiology.

METHODS

In this randomized, open-label study, 15 anaesthetized, mechanically ventilated and instrumented (renal artery flow probe and renal vein catheter) pigs were randomized in two disease severity groups-low severity (LS) sepsis (0.5 g/kg of autologous faeces intraperitoneally) and high severity (HS) sepsis (1 g/kg of autologous faeces intraperitoneally). Sequential cortical biopsies of the left kidney were performed and a pyramid-shaped kidney specimen with cortex, medulla and renal papilla was resected and processed at the end of the experiment. Oxygraphic data and western blot analysis of proteins involved in mitochondrial biogenesis and degradation were obtained.

RESULTS

In contrast to increased mitochondrial activity observed in LS sepsis, a significant decrease in the oxidative phosphorylation capacity together with an increase in the respiratory system uncoupling was observed during the first 24 h after sepsis induction in the HS group. Those changes preceded alterations of renal haemodynamics. Furthermore, serum creatinine rose significantly during the first 24 h, indicating that renal dysfunction is not primarily driven by haemodynamic changes. Compared to cortex, renal medulla had significantly lower oxidative phosphorylation capacity and electron-transport system activity. PGC-1-alfa, a marker of mitochondrial biogenesis, was significantly decreased in HS group.

CONCLUSIONS

In this experimental model, unique sequential tissue data show that the nature and dynamics of renal mitochondrial responses to sepsis are profoundly determined by the severity of infectious challenge and resulting magnitude of inflammatory insult. High disease severity is associated with early and stepwise progression of mitochondria dysfunction and acute kidney injury, both occurring independently from later renal macro-haemodynamic alterations. Our data may help explain the conflicting results of preclinical studies and suggest that sepsis encompasses a very broad spectrum of sepsis-induced acute kidney injury endotypes.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Small Molecule Modulators of AMP-Activated Protein Kinase (AMPK) Activity and Their Potential in Cancer Therapy

AMP-activated protein kinase (AMPK) is a central mediator of cellular metabolism and is activated in direct response to low ATP levels. Activated AMPK inhibits anabolic pathways and promotes catabolic activities that generate ATP through the phosphorylation of multiple target substrates. AMPK is a therapeutic target for activation in several chronic metabolic diseases, and there is increasing interest in targeting AMPK activity in cancer where it can act as a tumor suppressor or conversely it can support cancer cell survival. Small molecule AMPK activators and inhibitors have demonstrated some success in suppressing cancer growth, survival, and drug resistance in preclinical cancer models. In this perspective, we summarize the role of AMPK in cancer and drug resistance, the influence of the tumor microenvironment on AMPK activity, and AMPK activator and inhibitor development. In addition, we discuss the potential importance of isoform-selective targeting of AMPK and approaches for selective AMPK targeting in cancer.

The Role of Mitochondrial Quality Control in Liver Diseases: Dawn of a Therapeutic Era

The liver is a vital metabolic organ that detoxifies substances, produces bile, stores nutrients, and regulates versatile metabolic processes. Maintaining normal liver cell function requires the prompt and delicate modulation of mitochondrial quality control (MQC), which encompasses a spectrum of processes such as mitochondrial fission, fusion, biogenesis, and mitophagy. Recent studies have shown that disruptions to this homeostatic status are closely linked to the advent and progression of a variety of acute and chronic liver diseases, including but not limited to alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease. However, the explicit mechanisms by which mitochondrial dysfunction impacts inflammatory pathways and cell death in the context of liver diseases remain unclear. In this narrative review, we provide a detailed description of MQC, analyze the mechanisms underpinning mitochondrial dysfunction induced by different detrimental insults, and further elucidate how imbalanced/disrupted MQC promotes the progression and aggravation of liver diseases, ultimately shedding light on the mitochondrion-centric therapeutic strategies for these pathophysiological entities.

Exploration of Novel Metabolic Mechanisms Underlying Primary Biliary Cholangitis Using Hepatic Metabolomics, Lipidomics, and Proteomics Analysis

Metabolic reprogramming is important in primary biliary cholangitis (PBC) development. However, studies investigating the metabolic signature within the liver of PBC patients are limited. In this study, liver biopsies from 31 PBC patients and 15 healthy controls were collected, and comprehensive metabolomics, lipidomics, and proteomics analysis were conducted to characterize the metabolic landscape in PBC. We observed distinct lipidome remodeling in PBC with increased polyunsaturated fatty acid levels and augmented fatty acid β-oxidation (FAO), evidenced by the increased acylcarnitine levels and upregulated expression of proteins involved in FAO. Notably, PBC patients exhibited an increase in glucose-6-phosphate (G6P) and purines, alongside a reduction in pyruvate, suggesting impaired glycolysis and increased purines biosynthesis in PBC. Additionally, the accumulation of bile acids as well as a decrease in branched chain amino acids and aromatic amino acids were observed in PBC liver. We also observed an aberrant upregulation of proteins associated with ductular reaction, apoptosis, and autophagy. In conclusion, our study highlighted substantial metabolic reprogramming in glycolysis, fatty acid metabolism, and purine biosynthesis, coupled with aberrant upregulation of proteins associated with apoptosis and autophagy in PBC patients. Targeting the specific metabolic reprogramming may offer potential targets for the therapeutic intervention of PBC.

The autophagy component LC3 regulates lymphocyte adhesion via LFA1 transport in response to outside-in signaling

The leukocyte integrin LFA1 is indispensable for immune responses, orchestrating lymphocyte trafficking and adhesion. While LFA1 activation induces LFA1 clustering at the cell contact surface via outside-in signaling, the regulatory mechanisms remain unclear. Here, we uncovered a previously hidden function of the autophagosome component LC3 beyond its role in autophagy by bridging two seemingly unrelated pathways: LFA1 transport and autophagosome transport. LFA1 clusters co-trafficked with LC3, facilitating LFA1 accumulation at the contact surface. LC3b knockout decreased lymphocyte adhesiveness. LFA1 activation did not induce autophagy, whereas it increased mTOR and AMPK activity. LFA1-dependent AMPK activation enhances LFA1 and LC3 clustering and adhesion. Inhibiting Mst1 kinase-mediated LC3 phosphorylation promoted LC3-mediated LFA1 recruitment to the contact surface through direct interaction with RAPL, uncovering an unprecedented integrin recruitment route. These findings uncover a function of LC3 and expand our understanding of lymphocyte regulation via LFA1.

Autophagy induced by metabolic processes leads to solid tumor cell metastatic dormancy and recurrence

A crucial cellular mechanism that has a complex impact on the biology of cancer, particularly in solid tumors, is autophagy. This review explores how metabolic processes trigger autophagy, which helps metastatic tumor cells go dormant and recur. During metastasis, tumor cells frequently encounter severe stressors, such as low oxygen levels and nutritional deprivation, which causes them to activate autophagy as a survival tactic. This process allows cancer stem cells (CSCs) to withstand severe conditions while also preserving their features. After years of dormancy, dormant disseminated tumor cells (DTCs) may reappear as aggressive metastatic cancers. The capacity of autophagy to promote resistance to treatments and avoid immune detection is intimately related to this phenomenon. According to recent research, autophagy promotes processes, such as the epithelial-to-mesenchymal transition (EMT) and helps build a pre-metastatic niche, which makes treatment strategies more challenging. Autophagy may be a promising therapeutic target because of its dual function as a tumor suppressor in early-stage cancer and a survival promoter in advanced stages. To effectively treat metastatic diseases, it is crucial to comprehend how metabolic processes interact with autophagy and affect tumor behavior. In order to find novel therapeutic approaches that can interfere with these processes and improve patient outcomes, this study highlights the critical need for additional investigation into the mechanisms by which autophagy controls tumor dormancy and recurrence.

Metformin-induced mitophagy suppresses auditory hair cell apoptosis via AMPK pathway

Hearing loss is a pervasive issue affecting numerous individuals, and its etiology and categorization are multifaceted. Among these, sensorineural hearing loss (SNHL) emerges as the most prevalent variant among these. The primary causative factor underlying SNHL resides in the depletion of auditory hair cells within the cochlea, yet the pursuit of efficacious therapeutic interventions remains an ongoing challenge. Previous investigations have illuminated the role of mitochondrial dysfunction in precipitating cellular apoptosis, and mitophagy has emerged as a promising mechanism to ameliorate such dysfunction. Additionally, it has been noted that metformin possesses the specific ability to induce mitophagy. Herein, our objective is to explore the protective effects of metformin-induced mitophagy against apoptosis in auditory hair cells (HEI-OC1 cells) and explore its potential mechanisms. Our results revealed that metformin effectively triggered mitophagy in HEI-OC1 cells. Moreover, metformin treatment showed the ability to prevent tert-butyl hydroperoxide (TBHP) induced mitochondrial dysfunction and intrinsic apoptotic pathways. Mechanistically, we discovered that metformin activates AMP-activated protein kinase (AMPK) signaling in HEI-OC1 cells stimulated by TBHP, thereby triggering mitophagy. Overall, our results suggest that metformin may represent a promising and innovative therapeutic strategy for mitigating the onset of hearing loss.

The link between Mitochondria and Sarcopenia

Sarcopenia, a widespread condition, is characterized by a variety of factors influencing its development. The causes of sarcopenia differ depending on the age of the individual. It is defined as the combination of decreased muscle mass and impaired muscle function, primarily observed in association with ageing. As people age from 20 to 80 years old, there is an approximate 30% reduction in muscle mass and a 20% decline in cross-sectional area. This decline is attributed to a decrease in the size and number of muscle fibres. The regression of muscle mass and strength increases the risk of fractures, frailty, reduced quality of life, and loss of independence. Muscle cells, fibres, and tissues shrink, resulting in diminished muscle power, volume, and strength in major muscle groups. One prominent theory of cellular ageing posits a strong positive relationship between age and oxidative damage. Heightened oxidative stress leads to early-onset sarcopenia, characterized by neuromuscular innervation breakdown, muscle atrophy, and dysfunctional mitochondrial muscles. Ageing muscles generate more reactive oxygen species (ROS), and experience decreased oxygen consumption and ATP synthesis compared to younger muscles. Additionally, changes in mitochondrial protein interactions, cristae structure, and networks may contribute to ADP insensitivity, which ultimately leads to sarcopenia. Within this framework, this review provides a comprehensive summary of our current understanding of the role of mitochondria in sarcopenia and other muscle degenerative diseases, highlighting the crucial need for further research in these areas.

Targeting ferroptosis in gastrointestinal tumors: Interplay of iron-dependent cell death and autophagy

Ferroptosis is a regulated cell death mechanism distinct from apoptosis, autophagy, and necroptosis, marked by iron accumulation and lipid peroxidation. Since its identification in 2012, it has developed into a potential therapeutic target, especially concerning GI disorders like PC, HCC, GC, and CRC. This interest arises from the distinctive role of ferroptosis in the progression of diseases, presenting a new avenue for treatment where existing therapies fall short. Recent studies emphasize the promise of focusing on ferroptosis to fight GI cancers, showcasing its unique pathophysiological mechanisms compared to other types of cell death. By comprehending how ferroptosis aids in the onset and advancement of GI diseases, scientists aim to discover novel drug targets and treatment approaches. Investigating ferroptosis in gastrointestinal disorders reveals exciting possibilities for novel therapies, potentially revolutionizing cancer treatment and providing renewed hope for individuals affected by these tumors.

Oxidative stress of mitophagy in neurodegenerative diseases: Mechanism and potential therapeutic targets

Neurodegenerative diseases are now significant chronic progressive neurological conditions that affect individuals' physical health. Oxidative stress is crucial in the development of these diseases. Among the various neurodegenerative diseases, mitochondrial damage has become a major factor in oxidative stress and disease advancement. During this process, oxidative stress and mitophagy plays an important role. In this paper, we introduced the role of mitophagy and oxidative stress in detail, and expounded the relationship between them. In addition, we summarized the pathogenesis of some neurodegenerative diseases and the mechanism of three antioxidants. The former includes AD, PD, HD and ALS, while the latter includes carnosine, adiponectin and resveratrol. Provide goals and directions for further research and treatment of neurodegenerative diseases. This review summarizes the impact of oxidative stress on neurodegenerative diseases by regulating mitophagy, provides a deeper understanding of their pathological mechanisms, and suggests potential new therapeutic targets.

Recycle, repair, recover: the role of autophagy in modulating skeletal muscle repair and post-exercise recovery

Skeletal muscle is a highly plastic tissue that can adapt relatively rapidly to a range of stimuli. In response to novel mechanical loading, e.g. unaccustomed resistance exercise, myofibers are disrupted and undergo a period of ultrastructural remodeling to regain full physiological function, normally within 7 days. The mechanisms that underpin this remodeling are believed to be a combination of cellular processes including ubiquitin-proteasome/calpain-mediated degradation, immune cell infiltration, and satellite cell proliferation/differentiation. A relatively understudied system that has the potential to be a significant contributing mechanism to repair and recovery is the autophagolysosomal system, an intracellular process that degrades damaged and redundant cellular components to provide constituent metabolites for the resynthesis of new organelles and cellular structures. This review summarizes our current understanding of the autophagolysosomal system in the context of skeletal muscle repair and recovery. In addition, we also provide hypothetical models of how this system may interact with other processes involved in skeletal muscle remodeling and provide avenues for future research to improve our understanding of autophagy in human skeletal muscle.

Nanomaterial-enabled metabolic reprogramming strategies for boosting antitumor immunity

Immunotherapy has become a crucial strategy in cancer treatment, but its effectiveness is often constrained. Most cancer immunotherapies focus on stimulating T-cell-mediated immunity by driving the cancer-immunity cycle, which includes tumor antigen release, antigen presentation, T cell activation, infiltration, and tumor cell killing. However, metabolism reprogramming in the tumor microenvironment (TME) supports the viability of cancer cells and inhibits the function of immune cells within this cycle, presenting clinical challenges. The distinct metabolic needs of tumor cells and immune cells require precise and selective metabolic interventions to maximize therapeutic outcomes while minimizing adverse effects. Recent advances in nanotherapeutics offer a promising approach to target tumor metabolism reprogramming and enhance the cancer-immunity cycle through tailored metabolic modulation. In this review, we explore cutting-edge nanomaterial strategies for modulating tumor metabolism to improve therapeutic outcomes. We review the design principles of nanoplatforms for immunometabolic modulation, key metabolic pathways and their regulation, recent advances in targeting these pathways for the cancer-immunity cycle enhancement, and future prospects for next-generation metabolic nanomodulators in cancer immunotherapy. We expect that emerging immunometabolic modulatory nanotechnology will establish a new frontier in cancer immunotherapy in the near future.

Ferroptosis and pyroptosis are connected through autophagy: a new perspective of overcoming drug resistance

Drug resistance is a common challenge in clinical tumor treatment. A reduction in drug sensitivity of tumor cells is often accompanied by an increase in autophagy levels, leading to autophagy-related resistance. The effectiveness of combining chemotherapy drugs with autophagy inducers/inhibitors has been widely confirmed, but the mechanisms are still unclear. Ferroptosis and pyroptosis can be affected by various types of autophagy. Therefore, ferroptosis and pyroptosis have crosstalk via autophagy, potentially leading to a switch in cell death types under certain conditions. As two forms of inflammatory programmed cell death, ferroptosis and pyroptosis have different effects on inflammation, and the cGAS-STING signaling pathway is also involved. Therefore, it also plays an important role in the progression of some chronic inflammatory diseases. This review discusses the relationship between autophagy, ferroptosis and pyroptosis, and attempts to uncover the reasons behind the evasion of tumor cell death and the nature of drug resistance.

Aberrant STING activation promotes macrophage senescence by suppressing autophagy in vascular aging from diabetes

Diabetic vascular aging is driven by macrophage senescence, which propagates senescence-associated secretory phenotypes (SASP), exacerbating vascular dysfunction. This study utilized a type 2 diabetes mellitus (T2DM) mouse model induced by streptozotocin injection and a high-fat diet to investigate the role of STING in macrophage senescence. Vascular aging markers and senescent macrophages were assessed in vivo, while in vitro, high glucose treatment induced macrophage senescence, enhancing senescence in co-cultured vascular smooth muscle cells. Mechanistic studies revealed that STING activation inhibits autophagy by phosphorylating ULK1 at S757, accelerating senescence. Pharmacological modulation showed that the STING inhibitor H-151 alleviates, while the agonist DMXAA enhances, senescence. These findings highlight the STING-autophagy axis as a critical driver of macrophage senescence, offering insights into the molecular mechanisms of diabetic vascular aging and identifying potential therapeutic targets to mitigate vascular complications in diabetes.

Autophagy in brain tumors: molecular mechanisms, challenges, and therapeutic opportunities

Autophagy is responsible for maintaining cellular balance and ensuring survival. Autophagy plays a crucial role in the development of diseases, particularly human cancers, with actions that can either promote survival or induce cell death. However, brain tumors contribute to high levels of both mortality and morbidity globally, with resistance to treatments being acquired due to genetic mutations and dysregulation of molecular mechanisms, among other factors. Hence, having knowledge of the role of molecular processes in the advancement of brain tumors is enlightening, and the current review specifically examines the role of autophagy. The discussion would focus on the molecular pathways that control autophagy in brain tumors, and its dual role as a tumor suppressor and a supporter of tumor survival. Autophagy can control the advancement of different types of brain tumors like glioblastoma, glioma, and ependymoma, demonstrating its potential for treatment. Autophagy mechanisms can influence metastasis and drug resistance in glioblastoma, and there is a complex interplay between autophagy and cellular responses to stress like hypoxia and starvation. Autophagy can inhibit the growth of brain tumors by promoting apoptosis. Hence, focusing on autophagy could offer fresh perspectives on creating successful treatments.

Crosstalk between ferroptosis and autophagy: broaden horizons of cancer therapy

Ferroptosis and autophagy are two main forms of regulated cell death (RCD). Ferroptosis is a newly identified RCD driven by iron accumulation and lipid peroxidation. Autophagy is a self-degradation system through membrane rearrangement. Autophagy regulates the metabolic balance between synthesis, degradation and reutilization of cellular substances to maintain intracellular homeostasis. Numerous studies have demonstrated that both ferroptosis and autophagy play important roles in cancer pathogenesis and cancer therapy. We also found that there are intricate connections between ferroptosis and autophagy. In this article, we tried to clarify how different kinds of autophagy participate in the process of ferroptosis and sort out the common regulatory pathways between ferroptosis and autophagy in cancer. By exploring the complex crosstalk between ferroptosis and autophagy, we hope to broaden horizons of cancer therapy.