A regulatory signaling loop comprising the PGAM5 phosphatase and CK2 controls receptor-mediated mitophagy

Mitophagy in acute central nervous system injuries: regulatory mechanisms and therapeutic potentials

Acute central nervous system injuries, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury, are a major global health challenge. Identifying optimal therapies and improving the long-term neurological functions of patients with acute central nervous system injuries are urgent priorities. Mitochondria are susceptible to damage after acute central nervous system injury, and this leads to the release of toxic levels of reactive oxygen species, which induce cell death. Mitophagy, a selective form of autophagy, is crucial in eliminating redundant or damaged mitochondria during these events. Recent evidence has highlighted the significant role of mitophagy in acute central nervous system injuries. In this review, we provide a comprehensive overview of the process, classification, and related mechanisms of mitophagy. We also highlight the recent developments in research into the role of mitophagy in various acute central nervous system injuries and drug therapies that regulate mitophagy. In the final section of this review, we emphasize the potential for treating these disorders by focusing on mitophagy and suggest future research paths in this area.

Identification and validation of protein biomarkers for predicting gastrointestinal stromal tumor recurrence

We conducted a proteomic analysis using mass spectrometry to identify and validate protein biomarkers for accurately predicting recurrence risk in gastrointestinal stromal tumors (GIST) patients, focusing on differentially expressed proteins in metastatic versus primary GIST tissues. We selected five biomarkers-GPX4, RBM4, TPM3, PFKFB2, and PGAM5-and validated their expressions in primary tumors of recurrent and non-recurrent GIST patients via immunohistochemistry. Our analysis of the association between these biomarkers with recurrence-free survival (RFS) and overall survival (OS), along with their interrelationships, revealed that immunohistochemistry confirmed significantly higher expressions of these biomarkers in primary GIST tissues of recurrent patients. Kaplan-Meier survival analysis showed that high expressions of GPX4, RBM4, TPM3, PFKFB2, and PGAM5 correlated with lower RFS, and GPX4 and RBM4 with lower OS. All biomarker pairs showed positive associations, with high expressions correlating with increased recurrence rates, and GPX4 and RBM4 with higher mortality rates. In conclusion, the biomarkers GPX4, RBM4, TPM3, PFKFB2, and PGAM5 are clinically relevant for predicting GIST recurrence, with their high expressions in primary tumors linked to poorer RFS and OS. They serve as potential prognostic indicators, enabling early treatment and improved outcomes. The observed interrelationships among these biomarkers further validate their accuracy in predicting GIST recurrence.

AdipoR1 promotes pathogenic Th17 differentiation by regulating mitochondrial function through FUNDC1

Adiponectin receptor 1 ( Adipor1) deficiency has been shown to inhibit Th17 cell differentiation and reduce joint inflammation and bone erosion in antigen-induced arthritis (AIA) mice. Additional emerging evidence indicates that Th17 cells may differentiate into pathogenic (pTh17) and non-pathogenic (npTh17) cells, with the pTh17 cells playing a crucial role in numerous autoimmune and inflammatory conditions. In the current study, we found that Adipor1 deficiency inhibited pTh17 differentiation in vitro and that the deletion of Adipor1 in pTh17 cells reduced the mitochondrial function. RNA-sequencing (RNA-seq) demonstrated a significant increase in the expression levels of Fundc1, a gene related to mitochondrial function, in Adipor1-deficient CD4 + T cells. Interference with the Fundc1 expression in Adipor1-deficient CD4 + T cells partially mitigated the effect of Adipor1 deficiency on mitochondrial function and pTh17 differentiation. In conclusion, the current study demonstrated a novel role of AdipoR1 in regulating mitochondrial function via FUNDC1 to promote pTh17 cell differentiation, providing some insights into potential therapeutic targets for autoimmune and inflammatory diseases.

Mechanisms of mitochondrial resilience in teleostean radial glia under hypoxic stress

Radial glial cells (RGCs) are remarkable cells, essential for normal development of the vertebrate central nervous system. In teleost fishes, RGCs play a pivotal role in neurogenesis and regeneration of injured neurons and glia. RGCs also exhibit resilience to environmental stressors like hypoxia via metabolic adaptations. In this study, we assessed the physiology of RGCs following varying degrees of hypoxia, with an emphasis on reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), mitophagy, and energy metabolism. Our findings demonstrated that hypoxia significantly elevated ROS production and induced MMP depolarization in RGCs. The mitochondrial disturbances were closely associated with increased mitophagy, based on the co-localization of mitochondria and lysosomes. Key mitophagy-related genes were also up-regulated, including those of the BNIP3/NIX mediated pathway as well as the FUNDC1 mediated pathway. Such responses suggest robust cellular mechanisms are initiated to counteract mitochondrial damage due to increasing hypoxia. A significant metabolic shift from oxidative phosphorylation to glycolysis was also observed in RGCs, which may underlie an adaptive response to sustain cellular function and viability following a reduction in oxygen availability. Furthermore, hypoxia inhibited the synthesis of mitochondrial complexes subunits in RGCs, potentially related to elevated HIF-2α expression with 3 % O2. Taken together, RGCs appear to exhibit complex adaptive responses to hypoxic stress, characterized by metabolic reprogramming and the activation of mitophagy pathways to mitigate mitochondrial dysfunction.

Targeting selective autophagy in CNS disorders by small-molecule compounds

Autophagy functions as the primary cellular mechanism for clearing unwanted intracellular contents. Emerging evidence suggests that the selective elimination of intracellular organelles through autophagy, compared to the increased bulk autophagic flux, is crucial for the pathological progression of central nervous system (CNS) disorders. Notably, autophagic removal of mitochondria, known as mitophagy, is well-understood in an unhealthy brain. Accumulated data indicate that selective autophagy of other substrates, including protein aggregates, liposomes, and endoplasmic reticulum, plays distinctive roles in various pathological stages. Despite variations in substrates, the molecular mechanisms governing selective autophagy can be broadly categorized into two types: ubiquitin-dependent and -independent pathways, both of which can be subjected to regulation by small-molecule compounds. Notably, natural products provide the remarkable possibility for future structural optimization to regulate the highly selective autophagic clearance of diverse substrates. In this context, we emphasize the selectivity of autophagy in regulating CNS disorders and provide an overview of chemical compounds capable of modulating selective autophagy in these disorders, along with the underlying mechanisms. Further exploration of the functions of these compounds will in turn advance our understanding of autophagic contributions to brain disorders and illuminate precise therapeutic strategies for these diseases.

RABIF promotes hepatocellular carcinoma progression through regulation of mitophagy and glycolysis

The RAB interacting factor (RABIF) is a putative guanine nucleotide exchange factor that also functions as a RAB-stabilizing holdase chaperone. It has been implicated in pathogenesis of several cancers. However, the functional role and molecular mechanism of RABIF in hepatocellular carcinoma (HCC) are not entirely known. Here, we demonstrate an upregulation of RABIF in patients with HCC, correlating with a poor prognosis. RABIF inhibition results in decreased HCC cell growth both in vitro and in vivo. Our study reveals that depleting RABIF attenuates the STOML2-PARL-PGAM5 axis-mediated mitophagy. Consequently, this reduction in mitophagy results in diminished mitochondrial reactive oxygen species (mitoROS) production, thereby alleviating the HIF1α-mediated downregulation of glycolytic genes HK1, HKDC1, and LDHB. Additionally, we illustrate that RABIF regulates glucose uptake by controlling RAB10 expression. Importantly, the knockout of RABIF or blockade of mitophagy sensitizes HCC cells to sorafenib. This study uncovers a previously unrecognized role of RABIF crucial for HCC growth and identifies it as a potential therapeutic target.

Mitochondrial Function and Dysfunction in White Adipocytes and Therapeutic Implications

For a long time, white adipocytes were thought to function as lipid storages due to the sizeable unilocular lipid droplet that occupies most of their space. However, recent discoveries have highlighted the critical role of white adipocytes in maintaining energy homeostasis and contributing to obesity and related metabolic diseases. These physiological and pathological functions depend heavily on the mitochondria that reside in white adipocytes. This article aims to provide an up-to-date overview of the recent research on the function and dysfunction of white adipocyte mitochondria. After briefly summarizing the fundamental aspects of mitochondrial biology, the article describes the protective role of functional mitochondria in white adipocyte and white adipose tissue health and various roles of dysfunctional mitochondria in unhealthy white adipocytes and obesity. Finally, the article emphasizes the importance of enhancing mitochondrial quantity and quality as a therapeutic avenue to correct mitochondrial dysfunction, promote white adipocyte browning, and ultimately improve obesity and its associated metabolic diseases. © 2024 American Physiological Society. Compr Physiol 14:5581-5640, 2024.

Mitophagy in Cell Death Regulation: Insights into Mechanisms and Disease Implications

Mitophagy, a selective form of autophagy, plays a crucial role in maintaining optimal mitochondrial populations, normal function, and intracellular homeostasis by monitoring and removing damaged or excess mitochondria. Furthermore, mitophagy promotes mitochondrial degradation via the lysosomal pathway, and not only eliminates damaged mitochondria but also regulates programmed cell death-associated genes, thus preventing cell death. The interaction between mitophagy and various forms of cell death has recently gained increasing attention in relation to the pathogenesis of clinical diseases, such as cancers and osteoarthritis, neurodegenerative, cardiovascular, and renal diseases. However, despite the abundant literature on this subject, there is a lack of understanding regarding the interaction between mitophagy and cell death. In this review, we discuss the main pathways of mitophagy, those related to cell death mechanisms (including apoptosis, ferroptosis, and pyroptosis), and the relationship between mitophagy and cell death uncovered in recent years. Our study offers potential directions for therapeutic intervention and disease diagnosis, and contributes to understanding the molecular mechanism of mitophagy.

Multiple roles of mitochondrial autophagy receptor FUNDC1 in mitochondrial events and kidney disease

This article reviews the latest research progress on the role of mitochondrial autophagy receptor FUN14 domain containing 1 (FUNDC1) in mitochondrial events and kidney disease. FUNDC1 is a protein located in the outer membrane of mitochondria, which maintains the function and quality of mitochondria by regulating mitochondrial autophagy, that is, the selective degradation process of mitochondria. The structural characteristics of FUNDC1 enable it to respond to intracellular signal changes and regulate the activity of mitochondrial autophagy through phosphorylation and dephosphorylation. During phosphorylation, unc-51-like kinase 1 (ULK1) promotes the activation of mitophagy by phosphorylating Ser17 of FUNDC1. In contrast, Src and CK2 kinases inhibit the interaction between FUNDC1 and LC3 by phosphorylating Tyr18 and Ser13, thereby inhibiting mitophagy. During dephosphorylation, PGAM5 phosphatase enhances the interaction between FUNDC1 and LC3 by dephosphorylating Ser13, thereby activating mitophagy. BCL2L1 inhibits the activity of PGAM5 by interacting with PGAM5, thereby preventing the dephosphorylation of FUNDC1 and inhibiting mitophagy. FUNDC1 plays an important role in mitochondrial events, participating in mitochondrial fission, maintaining the homeostasis of iron and proteins in mitochondrial matrix, and mediating crosstalk between mitochondria, endoplasmic reticulum and lysosomes, which have important effects on cell energy metabolism and programmed death. In the aspect of kidney disease, the abnormal function of FUNDC1 is closely related to the occurrence and development of many diseases. In acute kidney injury (AKI), cardiorenal syndrome (CRS), diabetic nephropathy (DN), chronic kidney disease (CKD) ,renal fibrosis (RF) and renal anemia, FUNDC1-mediated imbalance of mitophagy may be one of the key factors in disease progression. Therefore, in-depth study of the regulatory mechanism and function of FUNDC1 is of great significance for understanding the pathogenesis of renal disease and developing new treatment strategies.

Hypoxia-induced mitochondrial fission regulates the fate of bone marrow mesenchymal stem cells by maintaining HIF1α stabilization

For mesenchymal stem cells derived from bone marrow, a controlled reduction in ambient oxygen concentration has been recognized as a facilitator of osteogenic differentiation and the formation of calcium nodules. However, the specific molecular mechanisms underlying this phenotype remain unclear. The aim of this study was to elucidate the impact of hypoxia on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and to explore the involvement of mitophagy and the regulation of mitochondrial dynamics mediated by the mitochondrial dynamic regulatory factor FUN14 domain-containing 1 (FUNDC1). Our findings suggest that FUNDC1 is required for promoting osteogenic differentiation in BMSCs under hypoxic conditions. However, this effect was not dependent on FUNDC1-mediated mitophagy but rather on FUNDC1-mediated regulation of mitochondrial fission. At the mechanistic level, FUNDC1 binds more DNM1L and less OPA1 under hypoxic conditions, leading to an upsurge in mitochondrial division. This heightened mitochondrial division culminates in the increased translocation of Parkin to mitochondria, diminishing its interactions with HIF1α in the cytoplasm and consequently facilitating HIF1α deubiquitination and stabilization. In summary, FUNDC1-regulated mitochondrial division in hypoxic culture emerges as a critical determinant for the translocation of Parkin to mitochondria, ultimately maintaining HIF1α stabilization and promoting osteogenic differentiation.

PGAM5 interacts with and maintains BNIP3 to license cancer-associated muscle wasting

Regressing the accelerated degradation of skeletal muscle protein is a significant goal for cancer cachexia management. Here, we show that genetic deletion of Pgam5 ameliorates skeletal muscle atrophy in various tumor-bearing mice. pgam5 ablation represses excessive myoblast mitophagy and effectively suppresses mitochondria meltdown and muscle wastage. Next, we define BNIP3 as a mitophagy receptor constitutively associating with PGAM5. bnip3 deletion restricts body weight loss and enhances the gastrocnemius mass index in the age- and tumor size-matched experiments. The NH2-terminal region of PGAM5 binds to the PEST motif-containing region of BNIP3 to dampen the ubiquitination and degradation of BNIP3 to maintain continuous mitophagy. Finally, we identify S100A9 as a pro-cachectic chemokine via activating AGER/RAGE. AGER deficiency or S100A9 inhibition restrains skeletal muscle loss by weakening the interaction between PGAM5 and BNIP3. In conclusion, the AGER-PGAM5-BNIP3 axis is a novel but common pathway in cancer-associated muscle wasting that can be targetable. Abbreviation: AGER/RAGE: advanced glycation end-product specific receptor; BA1: bafilomycin A1; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; Ckm-Cre: creatinine kinase, muscle-specific Cre; CM: conditioned medium; CON/CTRL: control; CRC: colorectal cancer; FUNDC1: FUN14 domain containing 1; MAP1LC3A/LC3A: microtubule associated protein 1 light chain 3 alpha; PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase; S100A9: S100 calcium binding protein A9; SQSTM1/p62: sequestosome 1; TOMM20: translocase of outer mitochondrial membrane 20; TIMM23: translocase of inner mitochondrial membrane 23; TSKO: tissue-specific knockout; VDAC1: voltage dependent anion channel 1.

Iron chelators as mitophagy agents: Potential and limitations

Mitochondrial autophagy (mitophagy) is very important process for the maintenance of cellular homeostasis, functionality and survival. Its dysregulation is associated with high risk and progression numerous serious diseases (e.g., oncological, neurodegenerative and cardiovascular ones). Therefore, targeting mitophagy mechanisms is very hot topic in the biological and medicinal research. The interrelationships between the regulation of mitophagy and iron homeostasis are now becoming apparent. In short, mitochondria are central point for the regulation of iron homeostasis, but change in intracellular cheatable iron level can induce/repress mitophagy. In this review, relationships between iron homeostasis and mitophagy are thoroughly discussed and described. Also, therapeutic applicability of mitophagy chelators in the context of individual diseases is comprehensively and critically evaluated.

Emerging insights into pulmonary hypertension: the potential role of mitochondrial dysfunction and redox homeostasis

Pulmonary hypertension (PH) is heterogeneous diseases that can lead to death due to progressive right heart failure. Emerging evidence suggests that, in addition to its role in ATP production, changes in mitochondrial play a central role in their pathogenesis, regulating integrated metabolic and signal transduction pathways. This review focuses on the basic principles of mitochondrial redox status in pulmonary vascular and right ventricular disorders, a series of dysfunctional processes including mitochondrial quality control (mitochondrial biogenesis, mitophagy, mitochondrial dynamics, mitochondrial unfolded protein response) and mitochondrial redox homeostasis. In addition, we will summarize how mitochondrial renewal and dynamic changes provide innovative insights for studying and evaluating PH. This will provide us with a clearer understanding of the initial signal transmission of mitochondria in PH, which would further improve our understanding of the pathogenesis of PH.

Relationship between ferroptosis and mitophagy in acute lung injury: a mini-review

Acute lung injury (ALI) is one of the most deadly and prevalent diseases in the intensive care unit. Ferroptosis and mitophagy are pathological mechanisms of ALI. Ferroptosis aggravates ALI, whereas mitophagy regulates ALI. Ferroptosis and mitophagy are both closely related to reactive oxygen species (ROS). Mitophagy can regulate ferroptosis, but the specific relationship between ferroptosis and mitophagy is still unclear. This study summarizes previous research findings on ferroptosis and mitophagy, revealing their involvement in ALI. Examining the functions of mTOR and NLPR3 helps clarify the connection between ferroptosis and mitophagy in ALI, with the goal of establishing a theoretical foundation for potential therapeutic approaches in the future management of ALI.

The interplay between mitochondrial dynamics and autophagy: From a key homeostatic mechanism to a driver of pathology

The complex relationship between mitochondrial dynamics and autophagy illustrates how two cellular housekeeping processes are intimately linked, illuminating fundamental principles of cellular homeostasis and shedding light on disparate pathological conditions including several neurodegenerative disorders. Here we review the basic tenets of mitochondrial dynamics i.e., the concerted balance between fusion and fission of the organelle, and its interplay with macroautophagy and selective mitochondrial autophagy, also dubbed mitophagy, in the maintenance of mitochondrial quality control and ultimately in cell viability. We illustrate how conditions of altered mitochondrial dynamics reverberate on autophagy and vice versa. Finally, we illustrate how altered interplay between these two key cellular processes participates in the pathogenesis of human disorders affecting multiple organs and systems.

Role of mitophagy in pulmonary hypertension: Targeting the mechanism and pharmacological intervention

Mitophagy, a crucial pathway in eukaryotic cells, selectively eliminates dysfunctional mitochondria, thereby maintaining cellular homeostasis via mitochondrial quality control. Pulmonary hypertension (PH) refers to a pathological condition where pulmonary arterial pressure is abnormally elevated due to various reasons, and the underlying pathogenesis remains elusive. This article examines the molecular mechanisms underlying mitophagy, emphasizing its role in PH and the progress in elucidating related molecular signaling pathways. Additionally, it highlights current drug regulatory pathways, aiming to provide novel insights into the prevention and treatment of pulmonary hypertension.

Src inhibition rescues FUNDC1-mediated neuronal mitophagy in ischaemic stroke

BACKGROUND

Ischaemic stroke triggers neuronal mitophagy, while the involvement of mitophagy receptors in ischaemia/reperfusion (I/R) injury-induced neuronal mitophagy remain not fully elucidated. Here, we aimed to investigate the involvement of mitophagy receptor FUN14 domain-containing 1 (FUNDC1) and its modulation in neuronal mitophagy induced by I/R injury.

METHODS

Wild-type and FUNDC1 knockout mice were generated to establish models of neuronal I/R injury, including transient middle cerebral artery occlusion (tMCAO) in vivo and oxygen glucose deprivation/reperfusion in vitro. Stroke outcomes of mice with two genotypes were assessed. Neuronal mitophagy was analysed both in vivo and in vitro. Activities of FUNDC1 and its regulator Src were evaluated. The impact of Src on FUNDC1-mediated mitophagy was assessed through administration of Src antagonist PP1.

RESULTS

To our surprise, FUNDC1 knockout mice subjected to tMCAO showed stroke outcomes comparable to those of their wild-type littermates. Although neuronal mitophagy could be activated by I/R injury, FUNDC1 deletion did not disrupt neuronal mitophagy. Transient activation of FUNDC1, represented by dephosphorylation of Tyr18, was detected in the early stages (within 3 hours) of neuronal I/R injury; however, phosphorylated Tyr18 reappeared and even surpassed baseline levels in later stages (after 6 hours), accompanied by a decrease in FUNDC1-light chain 3 interactions. Spontaneous inactivation of FUNDC1 was associated with Src activation, represented by phosphorylation of Tyr416, which changed in parallel with the level of phosphorylated FUNDC1 (Tyr18) during neuronal I/R injury. Finally, FUNDC1-mediated mitophagy in neurons under I/R conditions can be rescued by pharmacological inhibition of Src.

CONCLUSIONS

FUNDC1 is inactivated by Src during the later stage (after 6 hours) of neuronal I/R injury, and rescue of FUNDC1-mediated mitophagy may serve as a potential therapeutic strategy for treating ischaemic stroke.

GPR50 regulates neuronal development as a mitophagy receptor

Neurons rely heavily on high mitochondrial metabolism to provide sufficient energy for proper development. However, it remains unclear how neurons maintain high oxidative phosphorylation (OXPHOS) during development. Mitophagy plays a pivotal role in maintaining mitochondrial quality and quantity. We herein describe that G protein-coupled receptor 50 (GPR50) is a novel mitophagy receptor, which harbors the LC3-interacting region (LIR) and is required in mitophagy under stress conditions. Although it does not localize in mitochondria under normal culturing conditions, GPR50 is recruited to the depolarized mitochondrial membrane upon mitophagy stress, which marks the mitochondrial portion and recruits the assembling autophagosomes, eventually facilitating the mitochondrial fragments to be engulfed by the autophagosomes. Mutations Δ502-505 and T532A attenuate GPR50-mediated mitophagy by disrupting the binding of GPR50 to LC3 and the mitochondrial recruitment of GPR50. Deficiency of GPR50 causes the accumulation of damaged mitochondria and disrupts OXPHOS, resulting in insufficient ATP production and excessive ROS generation, eventually impairing neuronal development. GPR50-deficient mice exhibit impaired social recognition, which is rescued by prenatal treatment with mitoQ, a mitochondrially antioxidant. The present study identifies GPR50 as a novel mitophagy receptor that is required to maintain mitochondrial OXPHOS in developing neurons.

Mitophagy in fibrotic diseases: molecular mechanisms and therapeutic applications

Mitophagy is a highly precise process of selective autophagy, primarily aimed at eliminating excess or damaged mitochondria to maintain the stability of both mitochondrial and cellular homeostasis. In recent years, with in-depth research into the association between mitophagy and fibrotic diseases, it has been discovered that this process may interact with crucial cellular biological processes such as oxidative stress, inflammatory responses, cellular dynamics regulation, and energy metabolism, thereby influencing the occurrence and progression of fibrotic diseases. Consequently, modulating mitophagy holds promise as a therapeutic approach for fibrosis. Currently, various methods have been identified to regulate mitophagy to prevent fibrosis, categorized into three types: natural drug therapy, biological therapy, and physical therapy. This review comprehensively summarizes the current understanding of the mechanisms of mitophagy, delves into its biological roles in fibrotic diseases, and introduces mitophagy modulators effective in fibrosis, aiming to provide new targets and theoretical basis for the investigation of fibrosis-related mechanisms and disease prevention.

Role of Autophagy and AMPK in Cancer Stem Cells: Therapeutic Opportunities and Obstacles in Cancer

Cancer stem cells represent a resilient subset within the tumor microenvironment capable of differentiation, regeneration, and resistance to chemotherapeutic agents, often using dormancy as a shield. Their unique properties, including drug resistance and metastatic potential, pose challenges for effective targeting. These cells exploit certain metabolic processes for their maintenance and survival. One of these processes is autophagy, which generally helps in energy homeostasis but when hijacked by CSCs can help maintain their stemness. Thus, it is often referred as an Achilles heel in CSCs, as certain cancers tend to depend on autophagy for survival. Autophagy, while crucial for maintaining stemness in cancer stem cells (CSCs), can also serve as a vulnerability in certain contexts, making it a complex target for therapy. Regulators of autophagy like AMPK (5' adenosine monophosphate-activated protein kinase) also play a crucial role in maintaining CSCs stemness by helping CSCs in metabolic reprogramming in harsh environments. The purpose of this review is to elucidate the interplay between autophagy and AMPK in CSCs, highlighting the challenges in targeting autophagy and discussing therapeutic strategies to overcome these limitations. This review focuses on previous research on autophagy and its regulators in cancer biology, particularly in CSCs, addresses the remaining unanswered questions, and potential targets for therapy are also brought to attention.

Physiological functions of ULK1/2

UNC-51-like kinases 1 and 2 (ULK1/2) are serine/threonine kinases that are best known for their evolutionarily conserved role in the autophagy pathway. Upon sensing the nutrient status of a cell, ULK1/2 integrate signals from upstream cellular energy sensors such as mTOR and AMPK and relay them to the downstream components of the autophagy machinery. ULK1/2 also play indispensable roles in the selective autophagy pathway, removing damaged mitochondria, invading pathogens, and toxic protein aggregates. Additional functions of ULK1/2 have emerged beyond autophagy, including roles in protein trafficking, RNP granule dynamics, and signaling events impacting innate immunity, axon guidance, cellular homeostasis, and cell fate. Therefore, it is no surprise that alterations in ULK1/2 expression and activity have been linked with pathophysiological processes, including cancer, neurological disorders, and cardiovascular diseases. Growing evidence suggests that ULK1/2 function as biological rheostats, tuning cellular functions to intra and extra-cellular cues. Given their broad physiological relevance, ULK1/2 are candidate targets for small molecule activators or inhibitors that may pave the way for the development of therapeutics for the treatment of diseases in humans.

Phytochemicals targeting mitophagy: Therapeutic opportunities and prospects for treating Alzheimer's disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder and the leading cause of age-related cognitive decline. Recent studies have established a close relationship between mitophagy and the pathogenesis of AD. Various phytochemicals have shown promising therapeutic effects in mitigating the onset and progression of AD. This review offers a comprehensive overview of the typical features of mitophagy and the underlying mechanisms leading to its occurrence in AD, highlighting its significance in the disease's pathogenesis and progression. Additionally, we examine the therapeutic mechanisms of synthetic drugs that induce mitophagy in AD. Finally, we summarize recent advances in research on phytochemicals that regulate mitophagy in the treatment of AD, potentially guiding the development of new anti-AD drugs.

Mitophagy at the crossroads of cancer development: Exploring the role of mitophagy in tumor progression and therapy resistance

Preserving a functional mitochondrial network is crucial for cellular well-being, considering the pivotal role of mitochondria in ensuring cellular survival, especially under stressful conditions. Mitophagy, the selective removal of damaged mitochondria through autophagy, plays a pivotal role in preserving cellular homeostasis by preventing the production of harmful reactive oxygen species from dysfunctional mitochondria. While the involvement of mitophagy in neurodegenerative diseases has been thoroughly investigated, it is becoming increasingly evident that mitophagy plays a significant role in cancer biology. Perturbations in mitophagy pathways lead to suboptimal mitochondrial quality control, catalyzing various aspects of carcinogenesis, including establishing metabolic plasticity, stemness, metabolic reconfiguration of cancer-associated fibroblasts, and immunomodulation. While mitophagy performs a delicate balancing act at the intersection of cell survival and cell death, mounting evidence indicates that, particularly in the context of stress responses induced by cancer therapy, it predominantly promotes cell survival. Here, we showcase an overview of the current understanding of the role of mitophagy in cancer biology and its potential as a target for cancer therapy. Gaining a more comprehensive insight into the interaction between cancer therapy and mitophagy has the potential to reveal novel targets and pathways, paving the way for enhanced treatment strategies for therapy-resistant tumors in the near future.

The Role of Endothelial Cell Mitophagy in Age-Related Cardiovascular Diseases

Aging is a major risk factor for cardiovascular diseases (CVD), and mitochondrial autophagy impairment is considered a significant physiological change associated with aging. Endothelial cells play a crucial role in maintaining vascular homeostasis and function, participating in various physiological processes such as regulating vascular tone, coagulation, angiogenesis, and inflammatory responses. As aging progresses, mitochondrial autophagy impairment in endothelial cells worsens, leading to the development of numerous cardiovascular diseases. Therefore, regulating mitochondrial autophagy in endothelial cells is vital for preventing and treating age-related cardiovascular diseases. However, there is currently a lack of systematic reviews in this area. To address this gap, we have written this review to provide new research and therapeutic strategies for managing aging and age-related cardiovascular diseases.

Mitophagy and spermatogenesis: Role and mechanisms

The mitophagy process, a type of macroautophagy, is the targeted removal of mitochondria. It is a type of autophagy exclusive to mitochondria, as the process removes defective mitochondria one by one. Mitophagy serves as an additional level of quality control by using autophagy to remove superfluous mitochondria or mitochondria that are irreparably damaged. During spermatogenesis, mitophagy can influence cell homeostasis and participates in a variety of membrane trafficking activities. Crucially, it has been demonstrated that defective mitophagy can impede spermatogenesis. Despite an increasing amount of evidence suggesting that mitophagy and mitochondrial dynamics preserve the fundamental level of cellular homeostasis, little is known about their role in developmentally controlled metabolic transitions and differentiation. It has been observed that male infertility is a result of mitophagy's impact on sperm motility. Furthermore, certain proteins related to autophagy have been shown to be present in mammalian spermatozoa. The mitochondria are the only organelle in sperm that can produce reactive oxygen species and finally provide energy for sperm movement. Furthermore, studies have shown that inhibited autophagy-infected spermatozoa had reduced motility and increased amounts of phosphorylated PINK1, TOM20, caspase 3/7, and AMPK. Therefore, in terms of reproductive physiology, mitophagy is the removal of mitochondria derived from sperm and the following preservation of mitochondria that are exclusively maternal.

Leukemia and mitophagy: a novel perspective for understanding oncogenesis and resistance

Mitophagy, the selective autophagic process that specifically degrades mitochondria, serves as a vital regulatory mechanism for eliminating damaged mitochondria and maintaining cellular balance. Emerging research underscores the central role of mitophagy in the initiation, advancement, and treatment of cancer. Mitophagy is widely acknowledged to govern mitochondrial homeostasis in hematopoietic stem cells (HSCs), influencing their metabolic dynamics. In this article, we integrate recent data to elucidate the regulatory mechanisms governing mitophagy and its intricate significance in the context of leukemia. An in-depth molecular elucidation of the processes governing mitophagy may serve as a basis for the development of pioneering approaches in targeted therapeutic interventions.

From macroautophagy to mitophagy: Unveiling the hidden role of mitophagy in gastrointestinal disorders

In this editorial, we comment on an article titled “Morphological and biochemical characteristics associated with autophagy in gastrointestinal diseases”, which was published in a recent issue of the World Journal of Gastroenterology. We focused on the statement that “autophagy is closely related to the digestion, secretion, and regeneration of gastrointestinal cells”. With advancing research, autophagy, and particularly the pivotal role of the macroautophagy in maintaining cellular equilibrium and stress response in the gastrointestinal system, has garnered extensive study. However, the significance of mitophagy, a unique selective autophagy pathway with ubiquitin-dependent and independent variants, should not be overlooked. In recent decades, mitophagy has been shown to be closely related to the occurrence and development of gastrointestinal diseases, especially inflammatory bowel disease, gastric cancer, and colorectal cancer. The interplay between mitophagy and mitochondrial quality control is crucial for elucidating disease mechanisms, as well as for the development of novel treatment strategies. Exploring the pathogenesis behind gastrointestinal diseases and providing individualized and efficient treatment for patients are subjects we have been exploring. This article reviews the potential mechanism of mitophagy in gastrointestinal diseases with the hope of providing new ideas for diagnosis and treatment.

Liver Cell Mitophagy in Metabolic Dysfunction-Associated Steatotic Liver Disease and Liver Fibrosis

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects approximately one-third of the global population. MASLD and its advanced-stage liver fibrosis and cirrhosis are the leading causes of liver failure and liver-related death worldwide. Mitochondria are crucial organelles in liver cells for energy generation and the oxidative metabolism of fatty acids and carbohydrates. Recently, mitochondrial dysfunction in liver cells has been shown to play a vital role in the pathogenesis of MASLD and liver fibrosis. Mitophagy, a selective form of autophagy, removes and recycles impaired mitochondria. Although significant advances have been made in understanding mitophagy in liver diseases, adequate summaries concerning the contribution of liver cell mitophagy to MASLD and liver fibrosis are lacking. This review will clarify the mechanism of liver cell mitophagy in the development of MASLD and liver fibrosis, including in hepatocytes, macrophages, hepatic stellate cells, and liver sinusoidal endothelial cells. In addition, therapeutic strategies or compounds related to hepatic mitophagy are also summarized. In conclusion, mitophagy-related therapeutic strategies or compounds might be translational for the clinical treatment of MASLD and liver fibrosis.

Regulated cell death in hypoxic-ischaemic encephalopathy: recent development and mechanistic overview

Hypoxic-ischaemic encephalopathy (HIE) in termed infants remains a significant cause of morbidity and mortality worldwide despite the introduction of therapeutic hypothermia. Depending on the cell type, cellular context, metabolic predisposition and insult severity, cell death in the injured immature brain can be highly heterogenous. A continuum of cell death exists in the H/I-injured immature brain. Aside from apoptosis, emerging evidence supports the pathological activation of necroptosis, pyroptosis and ferroptosis as alternative regulated cell death (RCD) in HIE to trigger neuroinflammation and metabolic disturbances in addition to cell loss. Upregulation of autophagy and mitophagy in HIE represents an intrinsic neuroprotective strategy. Molecular crosstalk between RCD pathways implies one RCD mechanism may compensate for the loss of function of another. Moreover, mitochondrion was identified as the signalling "hub" where different RCD pathways converge. The highly-orchestrated nature of RCD makes them promising therapeutic targets. Better understanding of RCD mechanisms and crosstalk between RCD subtypes likely shed light on novel therapy development for HIE. The identification of a potential RCD converging node may open up the opportunity for simultaneous and synergistic inhibition of cell death in the immature brain.

Panax quinquefolius saponins and panax notoginseng saponins attenuate myocardial hypoxia-reoxygenation injury by reducing excessive mitophagy

OBJECTIVE

Panax quinquefolius saponins (PQS) and Panax notoginseng saponins (PNS) are key bioactive compounds in Panax quinquefolius L. and Panax notoginseng, commonly used in the treatment of clinical ischemic heart disease. However, their potential in mitigating myocardial ischemia-reperfusion injury remains uncertain. This study aims to evaluate the protective effects of combined PQS and PNS administration in myocardial hypoxia/reoxygenation (H/R) injury and explore the underlying mechanisms.

METHODS

To investigate the involvement of HIF-1α/BNIP3 mitophagy pathway in the myocardial protection conferred by PNS and PQS, we employed small interfering BNIP3 (siBNIP3) to silence key proteins of the pathway. H9C2 cells were categorized into four groups: control, H/R, H/R + PQS + PNS, and H/R + PQS + PNS+siBNIP3. Cell viability was assessed by Cell Counting Kit-8, apoptosis rates determined via flow cytometry, mitochondrial membrane potential assessed with the JC-1 fluorescent probes, intracellular reactive oxygen species detected with 2',7'-dichlorodihydrofluorescein diacetate, mitochondrial superoxide production quantified with MitoSOX Red, and autophagic flux monitored with mRFP-GFP-LC3 adenoviral vectors. Autophagosomes and their ultrastructure were visualized through transmission electron microscopy. Moreover, mRNA and protein levels were analyzed via real-time PCR and Western blotting.

RESULTS

PQS + PNS administration significantly increased cell viability, reduced apoptosis, lowered reactive oxygen species levels and mitochondrial superoxide production, mitigated mitochondrial dysfunction, and induced autophagic flux. Notably, siBNIP3 intervention did not counteract the cardioprotective effect of PQS + PNS. The PQS + PNS group showed downregulated mRNA expression of HIF-1α and BNIP3, along with reduced HIF-1α protein expression compared to the H/R group.

CONCLUSIONS

PQS + PNS protects against myocardial H/R injury, potentially by downregulating mitophagy through the HIF-1α/BNIP3 pathway.

Mechanisms involved in the regulation of mitochondrial quality control by PGAM5 in heart failure

Heart failure (HF) refers to a group of clinical syndromes in which various heart diseases lead to the inability of cardiac output to meet the metabolic needs of the body's tissues. Cardiac metabolism requires enormous amounts of energy; thus, impaired myocardial energy metabolism is considered a key factor in the occurrence and development of HF. Mitochondria serve as the primary energy source for cardiomyocytes, and their regular functionality underpins healthy cardiac function. The mitochondrial quality control system is a crucial mechanism for regulating the functionality of cardiomyocytes, and any abnormality in this system can potentially impact the morphology and structure of mitochondria, as well as the energy metabolism of cardiomyocytes. Phosphoglycerate mutase 5 (PGAM5), a multifunctional protein, plays a key role in the regulation of mitochondrial quality control through multiple pathways. Therefore, abnormal PGAM5 function is closely related to mitochondrial damage. This article reviews the mechanism of PGAM5's involvement in the regulation of the mitochondrial quality control system in the occurrence and development of HF, thereby providing a theoretical basis for future in-depth research.

Traditional Chinese medicine and mitophagy: A novel approach for cardiovascular disease management

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, imposing an enormous economic burden on individuals and human society. Laboratory studies have identified several drugs that target mitophagy for the prevention and treatment of CVD. Only a few of these drugs have been successful in clinical trials, and most studies have been limited to animal and cellular models. Furthermore, conventional drugs used to treat CVD, such as antiplatelet agents, statins, and diuretics, often result in adverse effects on patients' cardiovascular, metabolic, and respiratory systems. In contrast, traditional Chinese medicine (TCM) has gained significant attention for its unique theoretical basis and clinical efficacy in treating CVD.

PURPOSE

This paper systematically summarizes all the herbal compounds, extracts, and active monomers used to target mitophagy for the treatment of CVD in the last five years. It provides valuable information for researchers in the field of basic cardiovascular research, pharmacologists, and clinicians developing herbal medicines with fewer side effects, as well as a useful reference for future mitophagy research.

METHODS

The search terms "cardiovascular disease," "mitophagy," "herbal preparations," "active monomers," and "cardiac disease pathogenesis" in combination with "natural products" and "diseases" were used to search for studies published in the past five years until January 2024.

RESULTS

Studies have shown that mitophagy plays a significant role in the progression and development of CVD, such as atherosclerosis (AS), heart failure (HF), myocardial infarction (MI), myocardial ischemia/reperfusion injury (MI/RI), cardiac hypertrophy, cardiomyopathy, and arrhythmia. Herbal compound preparations, crude extracts, and active monomers have shown potential as effective treatments for these conditions. These substances protect cardiomyocytes by inducing mitophagy, scavenging damaged mitochondria, and maintaining mitochondrial homeostasis. They display notable efficacy in combating CVD.

CONCLUSION

TCM (including herbal compound preparations, extracts, and active monomers) can treat CVD through various pharmacological mechanisms and signaling pathways by inducing mitophagy. They represent a hotspot for future cardiovascular basic research and a promising candidate for the development of future cardiovascular drugs with fewer side effects and better therapeutic efficacy.

Mitochondrial quality control in human health and disease

Mitochondria, the most crucial energy-generating organelles in eukaryotic cells, play a pivotal role in regulating energy metabolism. However, their significance extends beyond this, as they are also indispensable in vital life processes such as cell proliferation, differentiation, immune responses, and redox balance. In response to various physiological signals or external stimuli, a sophisticated mitochondrial quality control (MQC) mechanism has evolved, encompassing key processes like mitochondrial biogenesis, mitochondrial dynamics, and mitophagy, which have garnered increasing attention from researchers to unveil their specific molecular mechanisms. In this review, we present a comprehensive summary of the primary mechanisms and functions of key regulators involved in major components of MQC. Furthermore, the critical physiological functions regulated by MQC and its diverse roles in the progression of various systemic diseases have been described in detail. We also discuss agonists or antagonists targeting MQC, aiming to explore potential therapeutic and research prospects by enhancing MQC to stabilize mitochondrial function.

Potential application of traditional Chinese medicine in age-related macular degeneration-focusing on mitophagy

Retinal pigment epithelial cell and neuroretinal damage in age-related macular degeneration (AMD) can lead to serious visual impairments and blindness. Studies have shown that mitophagy, a highly specialized cellular degradation system, is implicated in the pathogenesis of AMD. Mitophagy selectively eliminates impaired or non-functioning mitochondria via several pathways, such as the phosphatase and tensin homolog-induced kinase 1/Parkin, BCL2-interacting protein 3 and NIP3-like protein X, FUN14 domain-containing 1, and AMP-activated protein kinase pathways. This has a major impact on the maintenance of mitochondrial homeostasis. Therefore, the regulation of mitophagy could be a promising therapeutic strategy for AMD. Traditional Chinese medicine (TCM) uses natural products that could potentially prevent and treat various diseases, such as AMD. This review aims to summarize recent findings on mitophagy regulation pathways and the latest progress in AMD treatment targeting mitophagy, emphasizing methods involving TCM.

The structure and function of FUN14 domain-containing protein 1 and its contribution to cardioprotection by mediating mitophagy

Cardiovascular disease (CVD) is a serious public health risk, and prevention and treatment efforts are urgently needed. Effective preventive and therapeutic programs for cardiovascular disease are still lacking, as the causes of CVD are varied and may be the result of a multifactorial combination. Mitophagy is a form of cell-selective autophagy, and there is increasing evidence that mitophagy is involved in cardioprotective processes. Recently, many studies have shown that FUN14 domain-containing protein 1 (FUNDC1) levels and phosphorylation status are highly associated with many diseases, including heart disease. Here, we review the structure and functions of FUNDC1 and the path-ways of its mediated mitophagy, and show that mitophagy can be effectively activated by dephosphorylation of Ser13 and Tyr18 sites, phosphorylation of Ser17 site and ubiquitination of Lys119 site in FUNDC1. By effectively activating or inhibiting excessive mitophagy, the quality of mitochondria can be effectively controlled. The main reason is that, on the one hand, improper clearance of mitochondria and accumulation of damaged mitochondria are avoided, and on the other hand, excessive mitophagy causing apoptosis is avoided, both serving to protect the heart. In addition, we explore the possible mechanisms by which FUNDC1-mediated mitophagy is involved in exercise preconditioning (EP) for cardioprotection. Finally, we also point out unresolved issues in FUNDC1 and its mediated mitophagy and give directions where further research may be needed.

The role of mitophagy in the development of chronic kidney disease

Chronic kidney disease (CKD) represents a significant global health concern, with renal fibrosis emerging as a prevalent and ultimate manifestation of this condition. The absence of targeted therapies presents an ongoing and substantial challenge. Accumulating evidence suggests that the integrity and functionality of mitochondria within renal tubular epithelial cells (RTECs) often become compromised during CKD development, playing a pivotal role in the progression of renal fibrosis. Mitophagy, a specific form of autophagy, assumes responsibility for eliminating damaged mitochondria to uphold mitochondrial equilibrium. Dysregulated mitophagy not only correlates with disrupted mitochondrial dynamics but also contributes to the advancement of renal fibrosis in CKD. While numerous studies have examined mitochondrial metabolism, ROS (reactive oxygen species) production, inflammation, and apoptosis in kidney diseases, the precise pathogenic mechanisms underlying mitophagy in CKD remain elusive. The exact mechanisms through which modulating mitophagy mitigates renal fibrosis, as well as its influence on CKD progression and prognosis, have not undergone systematic investigation. The role of mitophagy in AKI has been relatively clear, but the role of mitophagy in CKD is still rare. This article presents a comprehensive review of the current state of research on regulating mitophagy as a potential treatment for CKD. The objective is to provide fresh perspectives, viable strategies, and practical insights into CKD therapy, thereby contributing to the enhancement of human living conditions and patient well-being.

Phosphoglycerate mutase 5 exacerbates liver ischemia-reperfusion injury by activating mitochondrial fission

Although the death of hepatocytes is a crucial trigger of liver ischemia-reperfusion (I/R) injury, the regulation of liver I/R-induced hepatocyte death is still poorly understood. Phosphoglycerate mutase 5 (PGAM5), a mitochondrial Serine/Threonine protein phosphatase, regulates mitochondrial dynamics and is involved in the process of both apoptosis and necrotic. However, it is still unclear what role PGAM5 plays in the death of hepatocytes induced by I/R. Using a PGAM5-silence mice model, we investigated the role of PGAM5 in liver I/R injury and its relevant molecular mechanisms. Our data showed that PGAM5 was highly expressed in mice with liver I/R injury. Silence of PGAM5 could decrease I/R-induced hepatocyte death in mice. In subcellular levels, the silence of PGAM5 could restore mitochondrial membrane potential, increase mitochondrial DNA copy number and transcription levels, inhibit ROS generation, and prevent I/R-induced opening of abnormal mPTP. As for the molecular mechanisms, we indicated that the silence of PGAM5 could inhibit Drp1(S616) phosphorylation, leading to a partial reduction of mitochondrial fission. In addition, Mdivi-1 could inhibit mitochondrial fission, decrease hepatocyte death, and attenuate liver I/R injury in mice. In conclusion, our data reveal the molecular mechanism of PGAM5 in driving hepatocyte death through activating mitochondrial fission in liver I/R injury.

Mitochondrial quality control pathways sense mitochondrial protein import

Mitochondrial quality control (MQC) mechanisms are required to maintain a functional proteome, which enables mitochondria to perform a myriad of important cellular functions from oxidative phosphorylation to numerous other metabolic pathways. Mitochondrial protein homeostasis begins with the import of over 1000 nuclear-encoded mitochondrial proteins and the synthesis of 13 mitochondrial DNA-encoded proteins. A network of chaperones and proteases helps to fold new proteins and degrade unnecessary, damaged, or misfolded proteins, whereas more extensive damage can be removed by mitochondrial-derived vesicles (MDVs) or mitochondrial autophagy (mitophagy). Here, focusing on mechanisms in mammalian cells, we review the importance of mitochondrial protein import as a sentinel of mitochondrial function that activates multiple MQC mechanisms when impaired.

CLPB disaggregase dysfunction impacts the functional integrity of the proteolytic SPY complex

CLPB is a mitochondrial intermembrane space AAA+ domain-containing disaggregase. CLPB mutations are associated with 3-methylglutaconic aciduria and neutropenia; however, the molecular mechanism underscoring disease and the contribution of CLPB substrates to disease pathology remains unknown. Interactions between CLPB and mitochondrial quality control (QC) factors, including PARL and OPA1, have been reported, hinting at dysregulation of organelle QC in disease. Utilizing proteomic and biochemical approaches, we show a stress-specific aggregation phenotype in a CLPB-null environment and define the CLPB substrate profile. We illustrate an interplay between intermembrane space proteins including CLPB, HAX1, HTRA2, and the inner membrane quality control proteins (STOML2, PARL, YME1L1; SPY complex), with CLPB deficiency impeding SPY complex function by virtue of protein aggregation in the intermembrane space. We conclude that there is an interdependency of mitochondrial QC components at the intermembrane space/inner membrane interface, and perturbations to this network may underscore CLPB disease pathology.

The E3 ubiquitin ligase MARCH2 protects against myocardial ischemia-reperfusion injury through inhibiting pyroptosis via negative regulation of PGAM5/MAVS/NLRP3 axis

Inflammasome activation and pyroptotic cell death are known to contribute to the pathogenesis of cardiovascular diseases, such as myocardial ischemia-reperfusion (I/R) injury, although the underlying regulatory mechanisms remain poorly understood. Here we report that expression levels of the E3 ubiquitin ligase membrane-associated RING finger protein 2 (MARCH2) were elevated in ischemic human hearts or mouse hearts upon I/R injury. Genetic ablation of MARCH2 aggravated myocardial infarction and cardiac dysfunction upon myocardial I/R injury. Single-cell RNA-seq analysis suggested that loss of MARCH2 prompted activation of NLRP3 inflammasome in cardiomyocytes. Mechanistically, phosphoglycerate mutase 5 (PGAM5) was found to act as a novel regulator of MAVS-NLRP3 signaling by forming liquid-liquid phase separation condensates with MAVS and fostering the recruitment of NLRP3. MARCH2 directly interacts with PGAM5 to promote its K48-linked polyubiquitination and proteasomal degradation, resulting in reduced PGAM5-MAVS co-condensation, and consequently inhibition of NLRP3 inflammasome activation and cardiomyocyte pyroptosis. AAV-based re-introduction of MARCH2 significantly ameliorated I/R-induced mouse heart dysfunction. Altogether, our findings reveal a novel mechanism where MARCH2-mediated ubiquitination negatively regulates the PGAM5/MAVS/NLRP3 axis to protect against cardiomyocyte pyroptosis and myocardial I/R injury.

Mechanisms of mitochondrial reorganization

The cytoplasm of eukaryotes is dynamically zoned by membrane-bound and membraneless organelles. Cytoplasmic zoning allows various biochemical reactions to take place at the right time and place. Mitochondrion is a membrane-bound organelle that provides a zone for intracellular energy production and metabolism of lipids and iron. A key feature of mitochondria is their high dynamics: mitochondria constantly undergo fusion and fission, and excess or damaged mitochondria are selectively eliminated by mitophagy. Therefore, mitochondria are appropriate model systems to understand dynamic cytoplasmic zoning by membrane organelles. In this review, we summarize the molecular mechanisms of mitochondrial fusion and fission as well as mitophagy unveiled through studies using yeast and mammalian models.

Mechanism and role of mitophagy in the development of severe infection

Mitochondria produce adenosine triphosphate and potentially contribute to proinflammatory responses and cell death. Mitophagy, as a conservative phenomenon, scavenges waste mitochondria and their components in the cell. Recent studies suggest that severe infections develop alongside mitochondrial dysfunction and mitophagy abnormalities. Restoring mitophagy protects against excessive inflammation and multiple organ failure in sepsis. Here, we review the normal mitophagy process, its interaction with invading microorganisms and the immune system, and summarize the mechanism of mitophagy dysfunction during severe infection. We highlight critical role of normal mitophagy in preventing severe infection.

Natural compounds modulating mitophagy: Implications for cancer therapy

Cancer is considered as the second leading cause of mortality, and cancer incidence is still growing rapidly worldwide, which poses an increasing global health burden. Although chemotherapy is the most widely used treatment for cancer, its effectiveness is limited by drug resistance and severe side effects. Mitophagy is the principal mechanism that degrades damaged mitochondria via the autophagy/lysosome pathway to maintain mitochondrial homeostasis. Emerging evidence indicates that mitophagy plays crucial roles in tumorigenesis, particularly in cancer therapy. Mitophagy can exhibit dual effects in cancer, with both cancer-inhibiting or cancer-promoting function in a context-dependent manner. A variety of natural compounds have been found to affect cancer cell death and display anticancer properties by modulating mitophagy. In this review, we provide a systematic overview of mitophagy signaling pathways, and examine recent advances in the utilization of natural compounds for cancer therapy through the modulation of mitophagy. Furthermore, we address the inquiries and challenges associated with ongoing investigations concerning the application of natural compounds in cancer therapy based on mitophagy. Overcoming these limitations will provide opportunities to develop novel interventional strategies for cancer treatment.

Mitophagy in intracerebral hemorrhage: a new target for therapeutic intervention

Intracerebral hemorrhage is a life-threatening condition with a high fatality rate and severe sequelae. However, there is currently no treatment available for intracerebral hemorrhage, unlike for other stroke subtypes. Recent studies have indicated that mitochondrial dysfunction and mitophagy likely relate to the pathophysiology of intracerebral hemorrhage. Mitophagy, or selective autophagy of mitochondria, is an essential pathway to preserve mitochondrial homeostasis by clearing up damaged mitochondria. Mitophagy markedly contributes to the reduction of secondary brain injury caused by mitochondrial dysfunction after intracerebral hemorrhage. This review provides an overview of the mitochondrial dysfunction that occurs after intracerebral hemorrhage and the underlying mechanisms regarding how mitophagy regulates it, and discusses the new direction of therapeutic strategies targeting mitophagy for intracerebral hemorrhage, aiming to determine the close connection between mitophagy and intracerebral hemorrhage and identify new therapies to modulate mitophagy after intracerebral hemorrhage. In conclusion, although only a small number of drugs modulating mitophagy in intracerebral hemorrhage have been found thus far, most of which are in the preclinical stage and require further investigation, mitophagy is still a very valid and promising therapeutic target for intracerebral hemorrhage in the long run.

Selective autophagy in cancer: mechanisms, therapeutic implications, and future perspectives

Eukaryotic cells engage in autophagy, an internal process of self-degradation through lysosomes. Autophagy can be classified as selective or non-selective depending on the way it chooses to degrade substrates. During the process of selective autophagy, damaged and/or redundant organelles like mitochondria, peroxisomes, ribosomes, endoplasmic reticulum (ER), lysosomes, nuclei, proteasomes, and lipid droplets are selectively recycled. Specific cargo is delivered to autophagosomes by specific receptors, isolated and engulfed. Selective autophagy dysfunction is closely linked with cancers, neurodegenerative diseases, metabolic disorders, heart failure, etc. Through reviewing latest research, this review summarized molecular markers and important signaling pathways for selective autophagy, and its significant role in cancers. Moreover, we conducted a comprehensive analysis of small-molecule compounds targeting selective autophagy for their potential application in anti-tumor therapy, elucidating the underlying mechanisms involved. This review aims to supply important scientific references and development directions for the biological mechanisms and drug discovery of anti-tumor targeting selective autophagy in the future.

Emerging roles of mitochondrial functions and epigenetic changes in the modulation of stem cell fate

Mitochondria serve as essential organelles that play a key role in regulating stem cell fate. Mitochondrial dysfunction and stem cell exhaustion are two of the nine distinct hallmarks of aging. Emerging research suggests that epigenetic modification of mitochondria-encoded genes and the regulation of epigenetics by mitochondrial metabolites have an impact on stem cell aging or differentiation. Here, we review how key mitochondrial metabolites and behaviors regulate stem cell fate through an epigenetic approach. Gaining insight into how mitochondria regulate stem cell fate will help us manufacture and preserve clinical-grade stem cells under strict quality control standards, contributing to the development of aging-associated organ dysfunction and disease.

Mitophagy in hypertension-mediated organ damage

Hypertension constitutes a pervasive chronic ailment on a global scale, frequently inflicting damage upon vital organs, such as the heart, blood vessels, kidneys, brain, and others. And this is a complex clinical dilemma that requires immediate attention. The mitochondria assume a crucial function in the generation of energy, and it is of utmost importance to eliminate any malfunctioning or surplus mitochondria to uphold intracellular homeostasis. Mitophagy is considered a classic example of selective autophagy, an important component of mitochondrial quality control, and is closely associated with many physiological and pathological processes. The ubiquitin-dependent pathway, facilitated by PINK1/Parkin, along with the ubiquitin-independent pathway, orchestrated by receptor proteins such as BNIP3, NIX, and FUNDC1, represent the extensively investigated mechanisms underlying mitophagy. In recent years, research has increasingly shown that mitophagy plays an important role in organ damage associated with hypertension. Exploring the molecular mechanisms of mitophagy in hypertension-mediated organ damage could represent a critical avenue for future research in the development of innovative therapeutic modalities. Therefore, this article provides a comprehensive review of the impact of mitophagy on organ damage due to hypertension.

FUNDC1/USP15/Drp1 ameliorated TNF-α-induced pulmonary artery endothelial cell proliferation by regulating mitochondrial dynamics

Mitochondrial dysfunction in pulmonary artery endothelial cells (PAECs) is related to the pathogenesis of pulmonary hypertension (PH). The mitochondrial receptor protein FUN14 domain containing 1 (FUNDC1) was found to be involved in pulmonary artery smooth muscle cell proliferation in PH. However, its role in PAECs remains unclear. We investigated FUNDC1 expression in the pulmonary artery endothelium in both monocrotaline-induced animal models and TNF-α-stimulated cell models. Additionally, the effect of FUNDC1 on PAECs proliferation and its possible mechanism were also investigated. We observed decreased FUNDC1 protein levels in animals and in vitro in PAECs. FUNDC1 deficiency in PAECs upregulated the expression of the deubiquitination enzyme ubiquitin-specific peptidase 15 (USP15), enhanced dynamin-related protein1 (Drp1)-mediated mitochondrial division, and increased mitochondrial ROS levels via the deubiquitination of Drp1. Additionally, FUNDC1 deficiency increased aerobic glycolysis, the production of ATP and lactic acid, and glucose uptake. FUNDC1 overexpression inhibited PAECs proliferation. Moreover, FUNDC1 overexpression in combination with a mitochondrial division or aerobic glycolysis inhibitor enhanced its inhibitory effect on cell proliferation. Our study findings suggest that FUNDC1 deficiency induced by inflammation can promote PAECs proliferation by regulating mitochondrial dynamics and cell energy metabolism via the USP15/Drp1 pathway.

Atg8 family proteins, LIR/AIM motifs and other interaction modes

The Atg8 family of ubiquitin-like proteins play pivotal roles in autophagy and other processes involving vesicle fusion and transport where the lysosome/vacuole is the end station. Nuclear roles of Atg8 proteins are also emerging. Here, we review the structural and functional features of Atg8 family proteins and their protein-protein interaction modes in model organisms such as yeast, Arabidopsis, C. elegans and Drosophila to humans. Although varying in number of homologs, from one in yeast to seven in humans, and more than ten in some plants, there is a strong evolutionary conservation of structural features and interaction modes. The most prominent interaction mode is between the LC3 interacting region (LIR), also called Atg8 interacting motif (AIM), binding to the LIR docking site (LDS) in Atg8 homologs. There are variants of these motifs like "half-LIRs" and helical LIRs. We discuss details of the binding modes and how selectivity is achieved as well as the role of multivalent LIR-LDS interactions in selective autophagy. A number of LIR-LDS interactions are known to be regulated by phosphorylation. New methods to predict LIR motifs in proteins have emerged that will aid in discovery and analyses. There are also other interaction surfaces than the LDS becoming known where we presently lack detailed structural information, like the N-terminal arm region and the UIM-docking site (UDS). More interaction modes are likely to be discovered in future studies.

FUNDC1/PFKP-mediated mitophagy induced by KD025 ameliorates cartilage degeneration in osteoarthritis

Osteoarthritis (OA) is the most common joint disease, but no disease-modifying drugs have been approved for OA treatment. Mitophagy participates in mitochondrial homeostasis regulation by selectively clearing dysfunctional mitochondria, which might contribute to cartilage degeneration in OA. Here, we provide evidence of impaired mitophagy in OA chondrocytes, which exacerbates chondrocyte degeneration. Among the several classic mitophagy-regulating pathways and receptors, we found that FUNDC1 plays a key role in preserving chondrocyte homeostasis by inducing mitophagy. FUNDC1 knockdown in vitro and knockout in vivo decreased mitophagy and exacerbated mitochondrial dysfunction, exacerbating chondrocyte degeneration and OA progression. FUNDC1 overexpression via intra-articular injection of adeno-associated virus alleviated cartilage degeneration in OA. Mechanistically, our study demonstrated that PFKP interacts with and dephosphorylates FUNDC1 to induce mitophagy in chondrocytes. Further analysis identified KD025 as a candidate drug for restoring chondrocyte mitophagy by increasing the FUNDC1-PFKP interaction and thus alleviating cartilage degeneration in mice with DMM-induced OA. Our study highlights the role of the FUNDC1-PFKP interaction in chondrocyte homeostasis via mitophagy induction and identifies KD025 as a promising agent for treating OA by increasing chondrocyte mitophagy.