Repairing Mitochondrial Dysfunction in Disease

Molecular mechanism of mitochondrial autophagy mediating impaired energy metabolism leading to osteoporosis

Osteoporosis (OP) is a bone metabolic disease caused by decreased bone mass leading to destruction of bone microstructure. Treatment of OP is characterized by a lifelong nature, causing extreme financial and psychological burdens to patients. Hormonal abnormalities, cellular autophagy, Ferroptosis, and oxidative stress are all part of the intricate and varied pathophysiology of OP. Recent research has revealed that mitochondrial dysfunction is a significant factor in the onset and progression of OP. By regulating bone marrow mesenchymal stem cell differentiation through various signaling pathways and cytokines, abnormal mitochondrial energy metabolism brought on by oxidative stress processes impacts osteoblast and osteoclast proliferation and differentiation, causing an imbalance in bone metabolism that ultimately results in OP. Therefore, one possible method to prevent and manage OP may be to use mitochondria as a carrier to trigger osteogenic differentiation of bone marrow mesenchymal stem cells from mitochondrial energy consumption, oxidative stress, autophagy, and osteoclast death. In order to offer some theoretical references and therapeutic approaches for the clinical prevention and treatment of OP, we will examine the pathophysiology of OP from mitochondrial dysfunction in this work.

The inhibition of PINK1/Drp1-mediated mitophagy by hyperglycemia leads to impaired osteoblastogenesis in diabetes

Impaired bone quality and increased fracture risk are cardinal features of the skeleton in diabetes mellitus. Hyperglycemia-induced oxidative stress is proposed as a potential underlying mechanism, but the precise pathogenic mechanism remains incompletely understood. In this investigation, osteoblasts under high glucose exhibited heightened levels of reactive oxygen species, impaired mitochondrial membrane potential, and profound inhibition of late-stage osteoblast differentiation. Further analyses uncovered that high glucose resulted in the downregulation of the PINK1/Drp1 pathway in osteoblasts, consequently leading to impaired mitophagy. Conversely, the upregulation of PINK1/Drp1 pathway activated mitophagy, which restored the differentiation capacity of osteoblasts. Notably, in an STZ-induced diabetic mouse model, BMP9 upregulated the expression of PINK1/Drp1 in the bone tissue, leading to an improvement in bone quality and bone mineral density. These findings suggest that the PINK1/Drp1 pathway might be a potential therapeutic target to enhance osteogenic differentiation and treat diabetic osteoporosis.

A Small-Molecule Drug for the Self-Checking of Mitophagy

Mitophagy, particularly in the context of drugs that disrupt mitochondrial membrane potential (MMP), represents a critical focus in pharmacology. However, the discovery and evaluation of MMP-disrupting drugs are often hampered using commercially available marker molecules that target similar or identical zones. These markers can significantly interfere with, obscure, or amplify the functional effects of MMP-targeting drugs, frequently leading to clinical failures. In response to this challenge, we propose a "one-two punch" drug design strategy that integrates both target-zone drug functionality and non-target zone biological reporting within a single small-molecule drug. We have developed a novel proof-of-concept mitophagy self-check drug (MitoSC) that exhibits dual-color and dual-localization properties. The functional component of this system is a variable MitoSC that disrupts mitochondrial membrane potential (MMP) homeostasis, thereby inducing mitophagy. Upon activation, this component transforms into a blue-fluorescent monomer (MitoSC-fun) specifically within the mitochondrial target zone. Concurrently, the biological reporting component is represented by a red-fluorescent monomer (MitoSC-rep) that localizes to lysosomes, the non-target zone. As mitophagy progresses, the fluorescent signals from MitoSC-rep (lysosomes) and MitoSC-fun (mitochondria) converge, enabling real-time monitoring of the mitophagic process. This strategy combines potent drug functionality with robust biological reporting, thereby minimizing interference and eliminating the complexities associated with external detection. Our findings underscore the potential of a single-molecule drug to exert target-zone specific actions while simultaneously providing non-target zone self-checking, offering a new perspective for drug design.

The mitochondrial integrated stress response: A novel approach to anti-aging and pro-longevity

The ISR is a cellular signaling pathway that responds to various physiological changes and types of stimulation. The mitochondrial integrated stress response (ISRmt) is a stress response specific to mitochondria which is initiated by eIF2α phosphorylation and is responsive to mitochondrial stressors. The ISRmt triggers diverse metabolic responses reliant on activating transcription factor 4 (ATF4). The preliminary phases of ISRmt can provoke an adaptive stress response that antagonizes age-related diseases and promotes longevity. In this review, we provide an overview of the molecular mechanisms of the ISRmt, with a particular focus on its potential as a therapeutic target for age-related disease and the promotion of longevity.

Preferential Synaptic Type of GABA-A Receptor Ligands Enhancing Neuronal Survival and Facilitating Functional Recovery After Ischemic Stroke

Selective enhancement of synaptic GABA signaling mediated by GABA-A receptors has been previously reported to promote functional recovery after ischemic stroke, while tonic GABA signaling has been detrimental. To identify agents that enhance synaptic signaling, we synthesized GABA-A ligands based on three chemotypes with affinity values pKi= 6.44-8.32. Representative compounds showed a preference in functional responses toward synaptic type of GABA-A receptors, compared to the extrasynaptic ones. In a cellular ischemia model (OGD), selected compounds showed the potential to improve neuronal recovery. The selected lead, compound 4, demonstrated the ability to reduce mitochondrial dysfunction, regulate intracellular calcium levels, decrease caspase 3 levels, and promote neurite outgrowth in in vitro assays. In an animal model, compound 4 enhanced motor recovery and showed neuroprotective activity by reducing infarct volume and decreasing poststroke acidosis. These findings underscore the value of selective ligands modulating synaptic GABA-A receptors in promoting recovery from ischemic stroke.

Mitochondrial-targeted therapies in traumatic brain injury: From bench to bedside

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide, with limited effective therapeutic options currently available. Recent research has highlighted the pivotal role of mitochondrial dysfunction in the pathophysiology of TBI, making mitochondria an attractive target for therapeutic intervention. This review comprehensively examines advancements in mitochondrial-targeted therapies for TBI, bridging the gap from basic research to clinical applications. We discuss the underlying mechanisms of mitochondrial damage in TBI, including oxidative stress, impaired bioenergetics, mitochondrial dynamics, and apoptotic pathways. Furthermore, we highlight the complex interplay between mitochondrial dysfunction, inflammation, and blood-brain barrier (BBB) integrity, elucidating how these interactions exacerbate injury and impede recovery. We also evaluate various preclinical studies exploring pharmacological agents, gene therapy, and novel drug delivery systems designed to protect and restore mitochondrial function. Clinical trials and their outcomes are assessed to evaluate the translational potential of mitochondrial-targeted therapies in TBI. By integrating findings from bench to bedside, this review emphasizes promising therapeutic avenues and addresses remaining challenges. It also provides guidance for future research to pave the way for innovative treatments that improve patient outcomes in TBI.

Mitochondrial-targeted liposome-based drug delivery - therapeutic potential and challenges

Liposomes, as nanocarriers for therapeutics, are a prominent focus in translational medicine. Given their biocompatibility, liposomes are suitable drug delivery systems rendering highly efficient therapeutic outcomes with minimal off-site toxicity. In different scenarios of human disease, it is essential not only to maintain therapeutic drug levels but also to target them to the appropriate intracellular compartment. Mitochondria regulate cellular signalling, calcium balance, and energy production, playing a crucial role in various human diseases. The notion of focusing on mitochondria for targeted drug delivery was proposed several decades ago, yet the practical application of this idea and its translation to clinical use is still in development. Mitochondrial-targeted liposomes offer an alternative to standard drug delivery systems, potentially reducing off-target interactions, side effects, and drug dosage or frequency. To advance this field, it is imperative to integrate various disciplines such as efficient chemical design, pharmacology, pharmaceutics, and cell biology. This review summarises scientific advances in the design, development and characterisation of novel liposome-based drug delivery systems targeting the mitochondria while revisiting their translational potential.

The potential mechanism of mitochondrial homeostasis in postoperative neurocognitive disorders: an in-depth review

Postoperative neurocognitive disorders (PND) are the most common neurological disorders following surgery and anaesthesia before and within 12 months after surgery, with a high prevalence in the geriatric population. PND can severely deteriorate the quality of life of patients, especially among the elderly, mainly manifested as memory loss, attention, decline and language comprehension disorders, mostly in elderly patients, with an incidence as high as 31%. Previous studies have also raised the possibility of accelerated cognitive decline and underlying neuropathological processes associated with diseases that affect cognitive performance (e.g. Alzheimer's dementia) for reasons related to anaesthesia and surgery. Currently, most research on PND has focused on various molecular pathways, especially in the geriatric population. The various hypotheses that have been proposed regarding the mechanisms imply peripheral neuroinflammation, oxidative stress, mitochondrial homeostasis, synaptic function, autophagy disorder, blood-brain barrier dysfunction, the microbiota-gut-brain axis and lack of neurotrophic support. However, the underlying pathogenesis and molecular mechanisms of PND have not yet been uncovered. Recent research has focused on mitochondrial homeostasis. In this paper, we present a review of various studies to better understand and characterize the mechanisms of associated cognitive dysfunction. As the biochemical basis of PND becomes more clearly defined, future treatments based on mitochondrial homeostasis modulation can prove to be very promising.

Sirtuin insights: bridging the gap between cellular processes and therapeutic applications

The greatest challenges that organisms face today are effective responses or detection of life-threatening environmental changes due to an obvious semblance of stress and metabolic fluctuations. These are associated with different pathological conditions among which cancer is most important. Sirtuins (SIRTs; NAD+-dependent enzymes) are versatile enzymes with diverse substrate preferences, cellular locations, crucial for cellular processes and pathological conditions. This article describes in detail the distinct roles of SIRT isoforms, unveiling their potential as either cancer promoters or suppressors and also explores how both natural and synthetic compounds influence the SIRT function, indicating promise for therapeutic applications. We also discussed the inhibitors/activators tailored to specific SIRTs, holding potential for diseases lacking effective treatments. It may uncover the lesser-studied SIRT isoforms (e.g., SIRT6, SIRT7) and their unique functions. This article also offers a comprehensive overview of SIRTs, linking them to a spectrum of diseases and highlighting their potential for targeted therapies, combination approaches, disease management, and personalized medicine. We aim to contribute to a transformative era in healthcare and innovative treatments by unraveling the intricate functions of SIRTs.

Procyanidin C1 ameliorates acidic pH stress induced nucleus pulposus degeneration through SIRT3/FOXO3-mediated mitochondrial dynamics

Intervertebral disc degeneration (IVDD) is a common cause of low back pain. Procyanidin C1 (PCC1) has been demonstrated to exert a protective effect on nucleus pulposus (NP) cells, and therefore, plays a critical role in the prevention and therapy of IVDD. Clarifying the pathophysiological characteristics and molecular mechanisms of IVDD may be helpful in establishing novel preventive and therapeutic strategies. This study aimed to investigate the probable mechanisms underlying the protection against acidic pH stress induced human NP cell injury. In vitro, acidic pH stress induced degeneration, mitochondrial dynamics imbalance, mitophagy, and mitochondria-mediated apoptosis in NP cells, all of which were ameliorated by PCC1. Autophagy inhibition partially eliminated the protective effects of PCC1 on mitochondrial homeostasis in NP cells. Moreover, PCC1 activated the sirtuin 3 (SIRT3)/forkhead box O3 (FOXO3) signaling pathway, a pivotal signaling pathway involved in the regulation of mitochondrial homeostasis in NP cells. In vivo, PCC1 ameliorated IVDD in a rat model and preserved the extracellular matrix of NP cells. Consequently, the protective effects of PCC1 on NP cells may inhibit IVDD progression via regulation of the SIRT3/FOXO3 signaling pathway. Therefore, regulation of the SIRT3/FOXO3 signaling pathway may be a novel preventive and therapeutic strategy for IVDD.

The role of CISD1 reduction in macrophages in promoting COPD development through M1 polarization and mitochondrial dysfunction

BACKGROUND

The mitochondrial dysfunction and oxidative stress imbalance caused by macrophage polarization play a role in the progression of COPD, with CDGSH iron-sulfur domain-containing protein 1 (CISD1) playing a key role. This study revealed the role and mechanism of CISD1 in smoke-induced macrophages.

METHODS

Using a pure cigarette smoke exposure-induced COPD mouse model, stimulation of Raw264.7 macrophages with cigarette smoke extract mimics the COPD environment. Knocking down CISD1 expression in macrophages and combining it with high-throughput sequencing to obtain subsequent differentially expressed genes and pathways. Macrophage polarization tendency under different treatments was determined using flow cytometry. Meanwhile, Mitosox, JC-1, DCFH-DA fluorescence intensity was measured to detect mitochondrial function and cellular oxidative stress levels. Western Blot technique was employed to validate autophagy (mitochondrial autophagy) pathway-related proteins. In addition, Elisa technique was used to measure inflammatory factors (IL-6, TNF-a) in the cell supernatant after co-culturing macrophages (Raw264.7) with epithelial cells (MLE12).

RESULTS

CISD1 is underexpressed in peripheral blood monocytes of COPD patients. Under in vitro conditions, we verified that cigarette smoke (smoke extract) indeed inhibits CISD1 expression in macrophages. Subsequently, we found that macrophages with knocked-down CISD1 tend to polarize towards M1 phenotype, and exhibit signs of mitochondrial dysfunction and oxidative stress imbalance. In addition, we observed significant activation of the autophagy pathway in CISD1-inhibited macrophages, with upregulation of LC3A/B and downregulation of p62 protein, as well as increased expression of mitochondrial autophagy-related proteins (PINK1, PARKN). Furthermore, co-culturing CISD1-knockdown macrophages (Raw264.7) with epithelial cells (MLE12) resulted in upregulation of inflammatory factors in the supernatant.

CONCLUSIONS

Smoke-induced reduction of CISD1 in macrophages promotes M1 polarization and mitochondrial dysfunction by activating the autophagy pathway, thereby promoting the occurrence and development of COPD.

Plant-inspired visible-light-driven bioenergetic hydrogels for chronic wound healing

Chronic bioenergetic imbalances and inflammation caused by hyperglycemia are obstacles that delay diabetic wound healing. However, it is difficult to directly deliver energy and metabolites to regulate intracellular energy metabolism using biomaterials. Herein, we propose a light-driven bioenergetic and oxygen-releasing hydrogel (PTKM@HG) that integrates the thylakoid membrane-encapsulated polyphenol nanoparticles (PTKM NPs) to regulate the energy metabolism and inflammatory response in diabetic wounds. Upon red light irradiation, the PTKM NPs exhibited oxygen generation and H2O2 deletion capacity through a photosynthetic effect to restore hypoxia-induced mitochondrial dysfunction. Meanwhile, the PTKM NPs could produce exogenous ATP and NADPH to enhance mitochondrial function and facilitate cellular anabolism by regulating the leucine-activated mTOR signaling pathway. Furthermore, the PTKM NPs inherited antioxidative and anti-inflammatory ability from polyphenol. Finally, the red light irradiated PTKM@HG hydrogel augmented the survival and migration of cells keratinocytes, and then accelerated angiogenesis and re-epithelialization of diabetic wounds. In short, this study provides possibilities for effectively treating diseases by delivering key metabolites and energy based on such a light-driven bioenergetic hydrogel.

Mitophagy Defects Exacerbate Inflammation and Aberrant Proliferation in Lymphocytic Thyroiditis

Background: Mitochondrial dysfunction in the thyroid due to defective mitophagy has been observed in lymphocytic thyroiditis (LT). However, the effect of impaired mitophagy on the pathogenesis of LT is not well understood. The aim of this study is to investigate the role of mitophagy dysregulation in the thyroid gland. Methods: We analyzed RNA sequencing data of human thyroid glands with/without LT from Genotype-Tissue Expression (GTEx; n = 653) and performed RNA sequencing in thyroid glands of phosphatase and tensin homolog-induced putative protein kinase 1 (Pink1) knock-out and wild-type mice. We evaluated the phenotypic and histopathologic characteristics of the human (n = 16) and mouse thyroids. Additionally, we assessed cell proliferation, reactive oxygen species (ROS) production, and cytokine secretion of human thyroid epithelial cells (HTori-3) treated with PINK1 siRNA or a mitophagy inhibitor. Results: We found that expression of PINK1, a key regulator of mitophagy, was compromised in human thyroids with LT. Thyroid glands of Pink1-deficient mice exhibited increased inflammatory responses and nodular hyperplasia. Furthermore, mitophagy defects led to the production of pro-inflammatory cytokines and ROS in thyroid cells, resulting in immune cell recruitment. Notably, these mitophagy defects upregulated both the RNA expression and protein secretion of amphiregulin (AREG), an epidermal growth factor receptor (EGFR) ligand, in thyroid cells, while decreasing the protein expression of cAMP response element-binding protein (CREB), a transcription factor that suppresses AREG transcription. Finally, we demonstrated that aberrant cell proliferation in thyroid cells, driven by mitophagy defects, was mitigated after treatment with cetuximab, an EGFR inhibitor. Conclusions: In this study, we observed that mitophagy defects in the thyroid not only intensify inflammation through the accumulation of ROS, cytokine production, and immune cell recruitment but also contribute to hyperplasia via the EGFR pathway, facilitated by increased secretion of AREG from thyroid cells.

Honokiol protects against diabetic retinal microvascular injury via sirtuin 3-mediated mitochondrial fusion

Introduction

Mitochondrial dysfunction and oxidative stress play important roles in diabetic retinal vascular injuries. Honokiol (HKL) is a small-molecule polyphenol that exhibits antioxidant effects and has a beneficial effect in diabetes. This study aimed to explore the potential ability of HKL to ameliorate vascular injury in diabetic retinopathy (DR) and its possible mechanisms of action.

Methods

The effect of HKL was evaluated in vascular injury in an in vivo type 2 diabetic (db/db) mouse model. In vitro, retinal microvascular endothelial cells were treated with high glucose (HG) to simulate the pathological diabetic environment. Cell viability, expression of apoptosis-related proteins, cellular reactive oxygen species, mitochondrial membrane potential, and morphological changes in the mitochondria were examined.

Results

The diabetic mice exhibited severe retinal vascular damage, including vascular leakage in vivo and capillary endothelial cell apoptosis in vitro. HKL reversed the retinal vascular leakage in the diabetic mice. In vitro, HKL improved retinal capillary endothelial cell viability, decreased apoptosis, and reversed the HG-induced increased cellular oxidative stress and mitochondrial fragmentation. The sirtuin 3 (SIRT3) inhibitor 3-TYP blocked all the in vivo and in vitro protective effects of HKL against diabetic retinal vascular leakage and capillary endothelium and eliminated the decrease in oxidative stress levels and reduction of mitochondrial fragmentation.

Discussion

In conclusion, these findings suggest that HKL inhibits vascular injury in DR, which was likely achieved through SIRT3-mediated mitochondrial fusion. This study provides a potential new strategy for the treatment of DR.

Benign prostatic hyperplasia nodules in patients treated with celecoxib and/or finasteride have reduced levels of NADH dehydrogenase [ubiquinone] iron-sulfur protein 3, a mitochondrial protein essential for efficient function of the electron transport chain

BACKGROUND

Benign prostatic hyperplasia (BPH) is a condition generally associated with advanced age in men that can be accompanied by bothersome lower urinary tract symptoms (LUTS) including intermittency, weak stream, straining, urgency, frequency, and incomplete bladder voiding. Pharmacotherapies for LUTS/BPH include alpha-blockers, which relax prostatic and urethral smooth muscle and 5ɑ-reductase inhibitors such as finasteride, which can block conversion of testosterone to dihydrotestosterone thereby reducing prostate volume. Celecoxib is a cyclooxygenase-2 inhibitor that reduces inflammation and has shown some promise in reducing prostatic inflammation and alleviating LUTS for some men with histological BPH. However, finasteride and celecoxib can reduce mitochondrial function in some contexts, potentially impacting their efficacy for alleviating BPH-associated LUTS.

METHODS

To determine the impact of these pharmacotherapies on mitochondrial function in prostate tissues, we performed immunostaining of mitochondrial Complex I (CI) protein NADH dehydrogenase [ubiquinone] iron-sulfur protein 3 (NDUFS3) and inflammatory cells on BPH specimens from patients naïve to treatment, or who were treated with celecoxib and/or finasteride for 28 days, as well as prostate tissues from male mice treated with celecoxib or vehicle control for 28 days. Quantification and statistical correlation analyses of immunostaining were performed.

RESULTS

NDUFS3 immunostaining was decreased in BPH compared to normal adjacent prostate. Patients treated with celecoxib and/or finasteride had significantly decreased NDUFS3 in both BPH and normal tissues, and no change in inflammatory cell infiltration compared to untreated patients. Mice treated with celecoxib also displayed a significant decrease in NDUFS3 immunostaining and no change in inflammatory cell infiltration.

CONCLUSIONS

These findings suggest that celecoxib and/or finasteride are associated with an overall decrease in NDUFS3 levels in prostate tissues but do not impact the presence of inflammatory cells, suggesting a decline in mitochondrial CI function in the absence of enhanced inflammation. Given that BPH has recently been associated with increased prostatic mitochondrial dysfunction, celecoxib and/or finasteride may exacerbate existing mitochondrial dysfunction in some BPH patients thereby potentially limiting their overall efficacy in providing metabolic stability and symptom relief.

Human neural stem cell-derived artificial organelles to improve oxidative phosphorylation

Oxidative phosphorylation (OXPHOS) in the mitochondrial inner membrane is a therapeutic target in many diseases. Neural stem cells (NSCs) show progress in improving mitochondrial dysfunction in the central nervous system (CNS). However, translating neural stem cell-based therapies to the clinic is challenged by uncontrollable biological variability or heterogeneity, hindering uniform clinical safety and efficacy evaluations. We propose a systematic top-down design based on membrane self-assembly to develop neural stem cell-derived oxidative phosphorylating artificial organelles (SAOs) for targeting the central nervous system as an alternative to NSCs. We construct human conditionally immortal clone neural stem cells (iNSCs) as parent cells and use a streamlined closed operation system to prepare neural stem cell-derived highly homogenous oxidative phosphorylating artificial organelles. These artificial organelles act as biomimetic organelles to mimic respiration chain function and perform oxidative phosphorylation, thus improving ATP synthesis deficiency and rectifying excessive mitochondrial reactive oxygen species production. Conclusively, we provide a framework for a generalizable manufacturing procedure that opens promising prospects for disease treatment.

Imbalanced Skeletal Muscle Mitochondrial Proteostasis Causes Bone Loss

Although microgravity has been implicated in osteoporosis, the precise molecular mechanism remains elusive. Here, we found that microgravity might induce mitochondrial protein buildup in skeletal muscle, alongside reduced levels of LONP1 protein. We revealed that disruptions in mitochondrial proteolysis, induced by the targeted skeletal muscle-specific deletion of the essential mitochondrial protease LONP1 or by the acute inducible deletion of muscle LONP1 in adult mice, cause reduced bone mass and compromised mechanical function. Moreover, the bone loss and weakness phenotypes were recapitulated in skeletal muscle-specific overexpressing ΔOTC mice, a known protein degraded by LONP1. Mechanistically, mitochondrial proteostasis imbalance triggered the mitochondrial unfolded protein response (UPRmt) in muscle, leading to an up-regulation of multiple myokines, including FGF21, which acts as a pro-osteoclastogenic factor. Surprisingly, this mitochondrial proteostasis stress influenced muscle-bone crosstalk independently of ATF4 in skeletal muscle. Furthermore, we established a marked association between serum FGF21 levels and bone health in humans. These findings emphasize the pivotal role of skeletal muscle mitochondrial proteostasis in responding to alterations in loading conditions and in coordinating UPRmt to modulate bone metabolism.

Microglia-induced neuroinflammation in hippocampal neurogenesis following traumatic brain injury

Traumatic brain injury (TBI) is one of the most causes of death and disability among people, leading to a wide range of neurological deficits. The important process of neurogenesis in the hippocampus, which includes the production, maturation and integration of new neurons, is affected by TBI due to microglia activation and the inflammatory response. During brain development, microglia are involved in forming or removing synapses, regulating the number of neurons, and repairing damage. However, in response to injury, activated microglia release a variety of pro-inflammatory cytokines, chemokines and other neurotoxic mediators that exacerbate post-TBI injury. These microglia-related changes can negatively affect hippocampal neurogenesis and disrupt learning and memory processes. To date, the intracellular signaling pathways that trigger microglia activation following TBI, as well as the effects of microglia on hippocampal neurogenesis, are poorly understood. In this review article, we discuss the effects of microglia-induced neuroinflammation on hippocampal neurogenesis following TBI, as well as the intracellular signaling pathways of microglia activation.

Puerarin ameliorates high glucose-induced MIN6 cell injury by activating PINK1/Parkin-mediated mitochondrial autophagy

The dysfunction of pancreatic β-cells plays a pivotal role in the pathogenesis of type 2 diabetes mellitus (T2DM). Despite numerous studies demonstrating the anti-inflammatory and antioxidant properties of puerarin, the protective effects of puerarin on β-cells remain poorly understood. Hence, this study aimed to explore the effects of puerarin on β-cell dysfunction in a hyperglycemic environment via the PINK/Parkin-mediated mitochondrial autophagy pathway. The alterations in cell viability of MIN6 cells exposed to glucose concentrations of 5 mM, 10 mM, 20 mM, and 30 mM for 24 h, 48 h, and 72 h, respectively, were assessed using the CCK-8 assay to optimize the modeling conditions. Subsequently, cellular insulin secretion was measured using enzyme-linked immunosorbent assay (ELISA), apoptosis rate by flow cytometry, mitochondrial membrane potential alteration by JC-1, cellular ROS production by the DCFH-DA fluorescent probe, and fusion of cellular autophagosomes and lysosomes through adenoviral infection analysis. Furthermore, gene and protein expression levels of the PINK/Parkin-mediated mitochondrial autophagy pathway and mitochondrial apoptosis pathway were assessed using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot, respectively. Results indicated a significant decrease in MIN6 cell viability following 48 h of exposure to 30 mM glucose concentration. Puerarin intervention markedly attenuated ROS production, restored mitochondrial membrane potential, induced PINK/Parkin-mediated mitochondrial autophagy, suppressed activation of the mitochondrial apoptotic pathway, mitigated apoptosis, and enhanced insulin secretion in a high glucose (HG) environment. The findings of this investigation contribute to a deeper understanding of the precise mechanism underlying the protective effects of puerarin on β-cells and offer a theoretical foundation for advancing puerarin-based therapeutics aimed at ameliorating T2DM.

Rotenone-Induced Optic Nerve Damage and Retinal Ganglion Cell Loss in Rats

Rotenone is a mitochondrial complex I inhibitor that causes retinal degeneration. A study of a rat model of rotenone-induced retinal degeneration suggested that this model is caused by indirect postsynaptic N-methyl-D-aspartate (NMDA) stimulation triggered by oxidative stress-mediated presynaptic intracellular calcium signaling. To elucidate the mechanisms by which rotenone causes axonal degeneration, we investigated morphological changes in optic nerves and the change in retinal ganglion cell (RGC) number in rats. Optic nerves and retinas were collected 3 and 7 days after the intravitreal injection of rotenone. The cross-sections of the optic nerves were subjected to a morphological analysis with axon quantification. The axons and somas of RGCs were analyzed immunohistochemically in retinal flatmounts. In the optic nerve, rotenone induced axonal swelling and degeneration with the incidence of reactive gliosis. Rotenone also significantly reduced axon numbers in the optic nerve. Furthermore, rotenone caused axonal thinning, fragmentation, and beading in RGCs on flatmounts and decreased the number of RGC soma. In conclusion, the intravitreal injection of rotenone in rats induced morphological abnormities with a reduced number of optic nerve axons and RGC axons when the RGC somas were degenerated. These findings help elucidate the pathogenesis of optic neuropathy induced by mitochondrial dysfunction.

Role of mitochondria in inflammatory lung diseases

Mitochondria play a significant and varied role in inflammatory lung disorders. Mitochondria, known as the powerhouse of the cell because of their role in producing energy, are now recognized as crucial regulators of inflammation and immunological responses. Asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome are characterized by complex interactions between immune cells, inflammatory substances, and tissue damage. Dysfunctional mitochondria can increase the generation of reactive oxygen species (ROS), triggering inflammatory pathways. Moreover, mitochondrial failure impacts cellular signaling, which in turn affects the expression of molecules that promote inflammation. In addition, mitochondria have a crucial role in controlling the behavior of immune cells, such as their activation and differentiation, which is essential in the development of inflammatory lung diseases. Their dynamic behavior, encompassing fusion, fission, and mitophagy, also impacts cellular responses to inflammation and oxidative stress. Gaining a comprehensive understanding of the intricate correlation between mitochondria and lung inflammation is essential in order to develop accurate treatment strategies. Targeting ROS generation, dynamics, and mitochondrial function may offer novel approaches to treating inflammatory lung diseases while minimizing tissue damage. Additional investigation into the precise contributions of mitochondria to lung inflammation will provide significant knowledge regarding disease mechanisms and potential therapeutic approaches. This review will focus on how mitochondria in the lung regulate these processes and their involvement in acute and chronic lung diseases.

Toxicity mechanism of acrolein on energy metabolism disorder and apoptosis in human ovarian granulosa cells

Acrolein (ACR), an unsaturated, highly reactive aldehyde, is a widespread environmental toxin. ACR exerts permanent and irreversible side effects on ovarian functions. Granulosa cells play a crucial role in supporting ovarian function. Thus, in this study, we investigated the toxicity effects of granulosa cells induced by ACR. Following treatment with varying ACR concentrations (0, 12.5, 25, 50, and 100 μM), we observed that ACR exposure induced reactive oxygen species accumulation, mitochondrial energy metabolism disorder, and apoptosis in KGN cells (a human ovarian granulosa cell line) in a dose-dependent manner. In addition, mitochondrial biogenesis in KGN cells displayed biphasic changes after ACR exposure, with activation at a low ACR dose (12.5 μM), but inhibition at higher ACR doses (≥50 μM). SIRT1/PGC-1α-mediated mitochondrial biogenesis is crucial for maintaining intracellular mitochondrial homeostasis and cellular function. The inhibition/activation of the SIRT1/PGC-1α pathway in KGN cells validated its role in ACR-induced damage. The results indicated that the inhibition of the SIRT1/PGC-1α pathway aggravated ACR-induced cell damage, whereas its activation partially counteracted ACR-induced cell damage. This study attempted to uncover a novel mechanism of ACR-induced ovarian toxicity so as to provide an effective treatment option for safeguarding female reproductive health from the adverse effects of ACR.

Recent progress of endoplasmic reticulum stress in the mechanism of atherosclerosis

The research progress of endoplasmic reticulum (ER) stress in atherosclerosis (AS) is of great concern. The ER, a critical cellular organelle, plays a role in important biological processes including protein synthesis, folding, and modification. Various pathological factors may cause ER stress, and sustained or excessive ER stress triggers the unfolded protein response, ultimately resulting in apoptosis and disease. Recently, researchers have discovered the importance of ER stress in the onset and advancement of AS. ER stress contributes to the occurrence of AS through different pathways such as apoptosis, inflammatory response, oxidative stress, and autophagy. Therefore, this review focuses on the mechanisms of ER stress in the development of AS and related therapeutic targets, which will contribute to a deeper understanding of the disease's pathogenesis and provide novel strategies for preventing and treating AS.

High-resolution in situ structures of mammalian respiratory supercomplexes

Mitochondria play a pivotal part in ATP energy production through oxidative phosphorylation, which occurs within the inner membrane through a series of respiratory complexes1-4. Despite extensive in vitro structural studies, determining the atomic details of their molecular mechanisms in physiological states remains a major challenge, primarily because of loss of the native environment during purification. Here we directly image porcine mitochondria using an in situ cryo-electron microscopy approach. This enables us to determine the structures of various high-order assemblies of respiratory supercomplexes in their native states. We identify four main supercomplex organizations: I1III2IV1, I1III2IV2, I2III2IV2 and I2III4IV2, which potentially expand into higher-order arrays on the inner membranes. These diverse supercomplexes are largely formed by 'protein-lipids-protein' interactions, which in turn have a substantial impact on the local geometry of the surrounding membranes. Our in situ structures also capture numerous reactive intermediates within these respiratory supercomplexes, shedding light on the dynamic processes of the ubiquinone/ubiquinol exchange mechanism in complex I and the Q-cycle in complex III. Structural comparison of supercomplexes from mitochondria treated under different conditions indicates a possible correlation between conformational states of complexes I and III, probably in response to environmental changes. By preserving the native membrane environment, our approach enables structural studies of mitochondrial respiratory supercomplexes in reaction at high resolution across multiple scales, from atomic-level details to the broader subcellular context.

The inhibition of MARCO by PolyG alleviates pulmonary fibrosis via regulating mitochondrial function in a silicotic rat model

Silicon dioxide (SiO2)-induced pulmonary fibrosis is potentially associated with the impairment of mitochondrial function. Previous research found that inhibition of macrophage receptor with collagenous structure (MARCO) could alleviate particle-induced lung injury by regulating phagocytosis and mitigating mitochondrial damage. The present study aims to explore the underlying anti-fibrosis mechanism of polyguanylic acid (PolyG, MARCO inhibitor) in a silicotic rat model. Hematoxylin and eosin and Masson staining were performed to visualize lung tissue pathological changes. Confocal microscopy, transmission electron microscope, western blot analysis, quantitative real-time PCR (qPCR), and adenosine triphosphate (ATP) content assay were performed to evaluate collagen content, mitochondrial function, and morphology changes in SiO2-induced rat pulmonary fibrosis. The results suggested that SiO2 exposure contributed to reactive oxygen species aggregation and the reduction of respiratory complexes and ATP synthesis. PolyG treatment could effectively reduce MARCO expression and ameliorate lung injury and fibrosis by rectifying the imbalance of mitochondrial respiration and energy synthesis. Furthermore, PolyG could maintain mitochondrial homeostasis by promoting peroxisome proliferator-activated receptor-coactivator 1 α (PGC1α)-mediated mitochondrial biogenesis and regulating fusion and fission. Together, PolyG could ameliorate SiO2-induced pulmonary fibrosis via inhibiting MARCO to protect mitochondrial function.

Mitochondrial DNA variants and microbiota: An experimental strategy to identify novel therapeutic potential in chronic inflammatory diseases

We previously demonstrated that mice carrying natural mtDNA variants of the FVB/NJ strain (m.7778 G>T in the mt-Atp8 gene in mitochondrial complex V), namely C57BL/6 J-mtFVB/NJ (B6-mtFVB), exhibited (i) partial protection from experimental skin inflammatory diseases in an anti-murine type VII collagen antibody-induced skin inflammation model and psoriasiform dermatitis model; (ii) significantly altered metabolites, including short-chain fatty acids, according to targeted metabolomics of liver, skin and lymph node samples; and (iii) a differential composition of the gut microbiota according to bacterial 16 S rRNA gene sequencing of stool samples compared to wild-type C57BL/6 J (B6) mice. To further dissect these disease-contributing factors, we induced an experimental antibody-induced skin inflammatory disease in gnotobiotic mice. We performed shotgun metagenomic sequencing of caecum contents and untargeted metabolomics of liver, CD4+ T cell, and caecum content samples from conventional B6-mtFVB and B6 mice. We identified D-glucosamine as a candidate mediator that ameliorated disease severity in experimental antibody-induced skin inflammation by modulating immune cell function in T cells, neutrophils and macrophages. Because mice carrying mtDNA variants of the FVB/NJ strain show differential disease susceptibility to a wide range of experimental diseases, including diet-induced atherosclerosis in low-density lipoprotein receptor knockout mice and collagen antibody-induced arthritis in DBA/1 J mice, this experimental approach is valuable for identifying novel therapeutic options for skin inflammatory conditions and other chronic inflammatory diseases to which mice carrying specific mtDNA variants show differential susceptibility.

Towards Healthy Longevity: Comprehensive Insights from Molecular Targets and Biomarkers to Biological Clocks

Aging is a complex and time-dependent decline in physiological function that affects most organisms, leading to increased risk of age-related diseases. Investigating the molecular underpinnings of aging is crucial to identify geroprotectors, precisely quantify biological age, and propose healthy longevity approaches. This review explores pathways that are currently being investigated as intervention targets and aging biomarkers spanning molecular, cellular, and systemic dimensions. Interventions that target these hallmarks may ameliorate the aging process, with some progressing to clinical trials. Biomarkers of these hallmarks are used to estimate biological aging and risk of aging-associated disease. Utilizing aging biomarkers, biological aging clocks can be constructed that predict a state of abnormal aging, age-related diseases, and increased mortality. Biological age estimation can therefore provide the basis for a fine-grained risk stratification by predicting all-cause mortality well ahead of the onset of specific diseases, thus offering a window for intervention. Yet, despite technological advancements, challenges persist due to individual variability and the dynamic nature of these biomarkers. Addressing this requires longitudinal studies for robust biomarker identification. Overall, utilizing the hallmarks of aging to discover new drug targets and develop new biomarkers opens new frontiers in medicine. Prospects involve multi-omics integration, machine learning, and personalized approaches for targeted interventions, promising a healthier aging population.

Roles of Mitochondrial Dysfunction in Diabetic Kidney Disease: New Perspectives from Mechanism to Therapy

Diabetic kidney disease (DKD) is a common microvascular complication of diabetes and the main cause of end-stage renal disease around the world. Mitochondria are the main organelles responsible for producing energy in cells and are closely involved in maintaining normal organ function. Studies have found that a high-sugar environment can damage glomeruli and tubules and trigger mitochondrial dysfunction. Meanwhile, animal experiments have shown that DKD symptoms are alleviated when mitochondrial damage is targeted, suggesting that mitochondrial dysfunction is inextricably linked to the development of DKD. This article describes the mechanisms of mitochondrial dysfunction and the progression and onset of DKD. The relationship between DKD and mitochondrial dysfunction is discussed. At the same time, the progress of DKD treatment targeting mitochondrial dysfunction is summarized. We hope to provide new insights into the progress and treatment of DKD.

Diterpenoid honatisine overcomes temozolomide resistance in glioblastoma by inducing mitonuclear protein imbalance through disruption of TFAM-mediated mtDNA transcription

BACKGROUND

Glioblastoma (GBM) represents as the most formidable intracranial malignancy. The systematic exploration of natural compounds for their potential applications in GBM therapy has emerged as a pivotal and fruitful avenue of research.

PURPOSE

In the present study, a panel of 96 diterpenoids was systematically evaluated as a repository of potential antitumour agents. The primary objective was to discern their potency in overcoming resistance to temozolomide (TMZ). Through an extensive screening process, honatisine, a heptacyclic diterpenoid alkaloid, emerged as the most robust candidate. Notably, honatisine exhibited remarkable efficacy in patient-derived primary and recurrent GBM strains. Subsequently, we subjected this compound to comprehensive scrutiny, encompassing GBM cultured spheres, GBM organoids (GBOs), TMZ-resistant GBM cell lines, and orthotopic xenograft mouse models of GBM cells.

RESULTS

Our investigative efforts delved into the mechanistic underpinnings of honatisine's impact. It was discerned that honatisine prompted mitonuclear protein imbalance and elicited the mitochondrial unfolded protein response (UPRmt). This effect was mediated through the selective depletion of mitochondrial DNA (mtDNA)-encoded subunits, with a particular emphasis on the diminution of mitochondrial transcription factor A (TFAM). The ultimate outcome was the instigation of deleterious mitochondrial dysfunction, culminating in apoptosis. Molecular docking and surface plasmon resonance (SPR) experiments validated honatisine's binding affinity to TFAM within its HMG-box B domain. This binding may promote phosphorylation of TFAM and obstruct the interaction of TFAM bound to heavy strand promoter 1 (HSP1), thereby enhancing Lon-mediated TFAM degradation. Finally, in vivo experiments confirmed honatisine's antiglioma properties. Our comprehensive toxicological assessments underscored its mild toxicity profile, emphasizing the necessity for a thorough evaluation of honatisine as a novel antiglioma agent.

CONCLUSION

In summary, our data provide new insights into the therapeutic mechanisms underlying honatisine's selective inducetion of apoptosis and its ability to overcome chemotherapy resistance in GBM. These actions are mediated through the disruption of mitochondrial proteostasis and function, achieved by the inhibition of TFAM-mediated mtDNA transcription. This study highlights honatisine's potential as a promising agent for glioblastoma therapy, underscoring the need for further exploration and investigation.

Arctigenin derivative A-1 ameliorates motor dysfunction and pathological manifestations in SOD1G93A transgenic mice via the AMPK/SIRT1/PGC-1α and AMPK/SIRT1/IL-1β/NF-κB pathways

AIM

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease characterized by progressive death of upper and lower motor neurons, leading to generalized muscle atrophy, paralysis, and even death. Mitochondrial damage and neuroinflammation play key roles in the pathogenesis of ALS. In the present study, the efficacy of A-1, a derivative of arctigenin with AMP-activated protein kinase (AMPK) and silent information regulator 1 (SIRT1) activation for ALS, was investigated.

METHODS

A-1 at 33.3 mg/kg was administrated in SOD1G93A transgenic mice orally from the 13th week for a 6-week treatment period. Motor ability was assessed before terminal anesthesia. Muscle atrophy and fibrosis, motor neurons, astrocytes, and microglia in the spinal cord were evaluated by H&E, Masson, Sirius Red, Nissl, and immunohistochemistry staining. Protein expression was detected with proteomics analysis, Western blotting, and ELISA. Mitochondrial adenosine triphosphate (ATP) and malondialdehyde (MDA) levels were measured using an assay kit.

RESULTS

A-1 administration in SOD1G93A mice enhanced mobility, decreased skeletal muscle atrophy and fibrosis, mitigated loss of spinal motor neurons, and reduced glial activation. Additionally, A-1 treatment improved mitochondrial function, evidenced by elevated ATP levels and increased expression of key mitochondrial-related proteins. The A-1 treatment group showed decreased levels of IL-1β, pIκBα/IκBα, and pNF-κB/NF-κB.

CONCLUSIONS

A-1 treatment reduced motor neuron loss, improved gastrocnemius atrophy, and delayed ALS progression through the AMPK/SIRT1/PGC-1α pathway, which promotes mitochondrial biogenesis. Furthermore, the AMPK/SIRT1/IL-1β/NF-κB pathway exerted neuroprotective effects by reducing neuroinflammation. These findings suggest A-1 as a promising therapeutic approach for ALS.

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.

The Therapeutic Effects of Baicalein on the Hepatopulmonary Syndrome in the Rat Model of Chronic Common Bile Duct Ligation

Background and Aims

Hepatopulmonary syndrome (HPS) is characterized by arterial oxygenation defects due to pulmonary vascular dilation in liver disease. To date, liver transplantation remains the only effective treatment for HPS. This study aimed to explore the preventative role of baicalein in HPS development.

Methods

Sixty male rats were randomly assigned to three groups: sham, common bile duct ligation (CBDL), and baicalein, receiving intraperitoneal injections of baicalein (40 mg·kg-1·d-1, diluted in saline) for 21 days. Survival rate, liver and kidney function, and bile acid metabolism levels were evaluated. Liver and lung angiogenesis and hepatic glycogen staining were assessed, and the expression of relevant proteins was evaluated by immunohistochemistry.

Results

Baicalein improved survival rates and hypoxemia in rats post-CBDL, reducing angiogenic protein levels and enhancing glucose homeostasis. Compared to the untreated group, baicalein suppressed the expression of vascular endothelial growth factor, placental growth factors, matrix metalloprotease 9 and C-X-C motif chemokine 2, and it increased the expression of glycemic regulatory proteins, including dipeptidyl peptidase-4, sirtuin 1, peroxisome proliferator-activated receptor gamma co-activator 1α, and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3.

Conclusion

Baicalein significantly improves hepatic function and hypoxia in HPS rats by attenuating pathological angiogenesis in the liver and lungs, showing promise as a treatment for HPS.

Matrix stiffening promotes chondrocyte senescence and the osteoarthritis development through downregulating HDAC3

Extracellular matrix (ECM) stiffening is a typical characteristic of cartilage aging, which is a quintessential feature of knee osteoarthritis (KOA). However, little is known about how ECM stiffening affects chondrocytes and other molecules downstream. This study mimicked the physiological and pathological stiffness of human cartilage using polydimethylsiloxane (PDMS) substrates. It demonstrated that epigenetic Parkin regulation by histone deacetylase 3 (HDAC3) represents a new mechanosensitive mechanism by which the stiffness matrix affected chondrocyte physiology. We found that ECM stiffening accelerated cultured chondrocyte senescence in vitro, while the stiffness ECM downregulated HDAC3, prompting Parkin acetylation to activate excessive mitophagy and accelerating chondrocyte senescence and osteoarthritis (OA) in mice. Contrarily, intra-articular injection with an HDAC3-expressing adeno-associated virus restored the young phenotype of the aged chondrocytes stimulated by ECM stiffening and alleviated OA in mice. The findings indicated that changes in the mechanical ECM properties initiated pathogenic mechanotransduction signals, promoted the Parkin acetylation and hyperactivated mitophagy, and damaged chondrocyte health. These results may provide new insights into chondrocyte regulation by the mechanical properties of ECM, suggesting that the modification of the physical ECM properties may be a potential OA treatment strategy.

Fludioxonil induces cardiotoxicity via mitochondrial dysfunction and oxidative stress in two cardiomyocyte models

Fludioxonil (Flu) is a phenylpyrrole fungicide and is currently used in over 900 agricultural products globally. Flu possesses endocrine-disrupting chemical-like properties and has been shown to mediate various physiological and pathological changes, such as apoptosis and differentiation, in diverse cell lines. However, the effects of Flu on cardiomyocytes have not been studied so far. The present study investigated the effects of Flu on mitochondria in AC16 human cardiomyocytes and H9c2 rat cardiomyoblasts. Flu decreased cell viability in a water-soluble tetrazolium assay and mediated morphological changes suggestive of apoptosis in AC16 and H9c2 cells. We confirmed that annexin V positive cells were increased by Flu through annexin V/propidium iodide staining. This suggests that the decrease in cell viability due to Flu may be associated with increased apoptotic changes. Flu consistently increased the expression of pro-apoptotic markers such as Bcl-2-associated X protein (Bax) and cleaved-caspase 3. Further, Flu reduced the oxygen consumption rate (OCR) in AC16 and H9c2 cells, which is associated with decreased mitochondrial membrane potential (MMP) as observed through JC-1 staining. In addition, Flu augmented the production of mitochondrial reactive oxygen species, which can trigger oxidative stress in cardiomyocytes. Taken together, these results indicate that Flu induces mitochondrial dysregulation in cardiomyocytes via the downregulation of the OCR and MMP and upregulation of the oxidative stress, consequently resulting in the apoptosis of cardiomyocytes. This study provides evidence of the risk of Flu toxicity on cardiomyocytes leading to the development of cardiovascular diseases and suggests that the use of Flu in agriculture should be done with caution and awareness of the probable health consequences of exposure to Flu.

Effects of mitochondrial dysfunction on cellular function: Role in atherosclerosis

Atherosclerosis, an immunoinflammatory disease of medium and large arteries, is associated with life-threatening clinical events, such as acute coronary syndromes and stroke. Chronic inflammation and impaired lipoprotein metabolism are considered to be among the leading causes of atherosclerosis, while numerous risk factors, including arterial hypertension, diabetes mellitus, obesity, and aging, can contribute to the development of the disease. In recent years, emerging evidence has underlined the key role of mitochondrial dysfunction in the pathogenesis of atherosclerosis. Mitochondrial dysfunction is believed to result in an increase in reactive oxygen species, leading to oxidative stress, chronic inflammation, and intracellular lipid deposition, all of which can contribute to the pathogenesis of atherosclerosis. Critical cells, including endothelial cells, vascular smooth muscle cells, and macrophages, play an important role in atherosclerosis. Mitochondrial function is also involved in maintaining the normal function of these cells. To better understand the relationship between mitochondrial dysfunction and atherosclerosis, this review summarizes the findings of recent studies and discusses the role of mitochondrial dysfunction in the risk factors and critical cells of atherosclerosis. FACTS: OPEN QUESTIONS.

ZIP transporters-regulated Zn2+ homeostasis: A novel determinant of human diseases

As an essential trace element for organisms, zinc participates in various physiological processes, such as RNA transcription, DNA replication, cell proliferation, and cell differentiation. The destruction of zinc homeostasis is associated with various diseases. Zinc homeostasis is controlled by the cooperative action of zinc transporter proteins that are responsible for the influx and efflux of zinc. Zinc transporter proteins are mainly categorized into two families: Zrt/Irt-like protein (SLC39A/ZIP) family and zinc transporter (SLC30A/ZNT) family. ZIP transporters contain 14 members, namely ZIP1-14, which can be further divided into four subfamilies. Currently, ZIP transporters-regulated zinc homeostasis is one of the research hotspots. Cumulative evidence suggests that ZIP transporters-regulated zinc homeostasis may cause physiological dysfunction and contribute to the onset and progression of diverse diseases, such as cancers, neurological diseases, and cardiovascular diseases. In this review, we initially discuss the structure and distribution of ZIP transporters. Furthermore, we comprehensively review the latest research progress of ZIP transporters-regulated zinc homeostasis in diseases, providing a new perspective into new therapeutic targets for treating related diseases.

Organ-Specific Mitochondrial Alterations Following Ischemia-Reperfusion Injury in Post-Cardiac Arrest Syndrome: A Comprehensive Review

BACKGROUND

Mitochondrial dysfunction, which is triggered by systemic ischemia-reperfusion (IR) injury and affects various organs, is a key factor in the development of post-cardiac arrest syndrome (PCAS). Current research on PCAS primarily addresses generalized mitochondrial responses, resulting in a knowledge gap regarding organ-specific mitochondrial dynamics. This review focuses on the organ-specific mitochondrial responses to IR injury, particularly examining the brain, heart, and kidneys, to highlight potential therapeutic strategies targeting mitochondrial dysfunction to enhance outcomes post-IR injury.

METHODS AND RESULTS

We conducted a narrative review examining recent advancements in mitochondrial research related to IR injury. Mitochondrial responses to IR injury exhibit considerable variation across different organ systems, influenced by unique mitochondrial structures, bioenergetics, and antioxidative capacities. Each organ demonstrates distinct mitochondrial behaviors that have evolved to fulfill specific metabolic and functional needs. For example, cerebral mitochondria display dynamic responses that can be both protective and detrimental to neuronal activity and function during ischemic events. Cardiac mitochondria show vulnerability to IR-induced oxidative stress, while renal mitochondria exhibit a unique pattern of fission and fusion, closely linked to their susceptibility to acute kidney injury. This organ-specific heterogeneity in mitochondrial responses requires the development of tailored interventions. Progress in mitochondrial medicine, especially in the realms of genomics and metabolomics, is paving the way for innovative strategies to combat mitochondrial dysfunction. Emerging techniques such as mitochondrial transplantation hold the potential to revolutionize the management of IR injury in resuscitation science.

CONCLUSIONS

The investigation into organ-specific mitochondrial responses to IR injury is pivotal in the realm of resuscitation research, particularly within the context of PCAS. This nuanced understanding holds the promise of revolutionizing PCAS management, addressing the unique mitochondrial dysfunctions observed in critical organs affected by IR injury.

Biomarkers of bipolar disorder based on metabolomics: A systematic review

Bipolar disorder (BD) is a severe affective disorder characterized by recurrent episodes of depression or mania/hypomania, which significantly impair cognitive function, life skills, and social abilities of patients. There is little understanding of the neurobiological mechanisms of BD. The diagnosis of BD is primarily based on clinical assessment and psychiatric examination, highlighting the urgent need for objective markers to facilitate the diagnosis of BD. Metabolomics can be used as a diagnostic tool for disease identification and evaluation. This study summarized the altered metabolites in BD and analyzed aberrant metabolic pathways, which might contribute to the diagnosis of BD. Search of PubMed and Web of science for human BD studies related to metabolism to identify articles published up to November 19, 2022 yielded 987 articles. After screening and applying the inclusion and exclusion criteria, 16 untargeted and 11 targeted metabolomics studies were included. Pathway analysis of the potential differential biometabolic markers was performed using the Kyoto encyclopedia of genes and genomes (KEGG). There were 72 upregulated and 134 downregulated biomarkers in the untargeted metabolomics studies using blood samples. Untargeted metabolomics studies utilizing urine specimens revealed the presence of 78 upregulated and 54 downregulated metabolites. The targeted metabolomics studies revealed abnormalities in the metabolism of glutamate and tryptophan. Enrichment analysis revealed that the differential metabolic pathways were mainly involved in the metabolism of glucose, amino acid and fatty acid. These findings suggested that certain metabolic biomarkers or metabolic biomarker panels might serve as a reference for the diagnosis of BD.

The role of mitochondrial quality control mechanisms in chondrocyte senescence

Chondrocytes are the exclusive cellular constituents of articular cartilage, and their functional status governs the health of the cartilage. The primary factor contributing to the deterioration of cartilage structure and function is chondrocyte senescence. In hypoxia and hypodextrose environment, chondrocytes heavily rely on glycolysis for energy metabolism. Mitochondria, acting as the regulatory hub for chondrocyte energy metabolism, exhibit dysfunction before chondrocyte senescence, indicating their crucial involvement in the process. Previous research has suggested that molecules associated with mitochondrial quality control mechanisms can effectively restore mitochondrial function and alleviate chondrocyte senescence. However, there remains to be clarity regarding the relationship between mitochondrial quality control mechanisms and differences in efficacy among various target molecules, which pose challenges when evaluating them in chondrocytes. By conducting a comprehensive review of the existing literature on mitochondrial quality control mechanisms and chondrocyte senescence, we gain further insights into this intricate relationship while identifying promising targets that could potentially open up novel avenues for the treatment of chondrocyte senescence.

PGC-1α activation ameliorates cancer-induced bone pain via inhibiting apoptosis of GABAergic interneurons

Cancer-induced bone pain (CIBP) stands out as one of the most challenging issues in clinical practice due to its intricate and not fully elucidated pathophysiological mechanisms. Existing evidence has pointed toward the significance of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) down-regulation in contributing to pain behaviors in various rodent models of neuropathic pain. In our current study, we aimed to investigate the role of PGC-1α in CIBP. Our results unveiled a reduction in PGC-1α expression within the spinal cord of CIBP rats, particularly in GABAergic interneurons. Notably, intrathecal administration of the PGC-1α activator ZLN005 suppressed the loss of spinal GABAergic interneurons. This suppression was achieved by inhibiting caspase-3-mediated apoptosis, ultimately leading to the alleviation of mechanical allodynia in CIBP rats. Further exploration into the mechanism revealed that PGC-1α activation played a pivotal role in mitigating ATP depletion and reactive oxygen species accumulation linked to mitochondrial dysfunction. This was achieved through the restoration of mitochondrial biogenesis and the activation of the SIRT3-SOD2 pathway. Impressively, the observed effects were prominently reversed upon the application of SR18292, a specific PGC-1α inhibitor. In conclusion, our findings strongly suggest that PGC-1α activation acts as a potent inhibitor of apoptosis in spinal GABAergic interneurons. This inhibition is mediated by the improvement of mitochondrial function, facilitated in part through the enhancement of mitochondrial biogenesis and the activation of the SIRT3-SOD2 pathway. The results of our study shed light on potential therapeutic avenues for addressing CIBP.

Mechanisms of hepatocellular toxicity associated with the components of St. John's Wort extract hypericin and hyperforin in HepG2 and HepaRG cells

St. John's Wort preparations are used for the treatment of mild to moderate depression. They are usually well tolerated but can cause adverse reactions including liver toxicity in rare cases. To date, the mechanism(s) underlying the hepatotoxicity of St. John's Wort extracts are poorly investigated. We studied the hepatocellular toxicity of hypericin and hyperforin as the two main ingredients of St. John's Wort extracts in HepG2 and HepaRG cells and compared the effects to citalopram (a synthetic serotonin uptake inhibitor) with a special focus on mitochondrial toxicity and oxidative stress. In HepG2 cells, hypericin was membrane-toxic at 100 µM and depleted ATP at 20 µM. In HepaRG cells, ATP depletion started at 5 µM. In comparison, hyperforin and citalopram were not toxic up to 100 µM. In HepG2 cells, hypericin decreased maximal respiration starting at 2 µM and mitochondrial ATP formation starting at 10 µM but did not affect glycolytic ATP production. Hypericin inhibited the activity of complex I, II and IV of the electron transfer system and caused mitochondrial superoxide accumulation in cells. The protein expression of mitochondrial superoxide dismutase 2 (SOD2) and thioredoxin 2 (TRX2) and total and reduced glutathione decreased in cells exposed to hypericin. Finally, hypericin diminished the mitochondrial DNA copy number and caused cell necrosis but not apoptosis. In conclusion, hypericin, but not hyperforin or citalopram, is a mitochondrial toxicant at low micromolar concentrations. This mechanism may contribute to the hepatotoxicity occasionally observed in susceptible patients treated with St. John's Wort preparations.

Collagen I protects human keratinocytes HaCaT against UVB injury via restoring PINK1/parkin-mediated mitophagy

Collagen I is a major component of extracellular matrix in human skin, and is also widely used in a variety of skin-care products. In this study, we investigated the modulatory roles of collagen I on human immortalized keratinocytes HaCaT, especially when cells were irradiated with UVB. Interestingly, the cells grown on plates coated by molecular collagen I, but not fibrillar collagen I, acquired certain resistance against UVB damages, as shown by increased survival and reduced apoptosis. The accumulation of dysfunctional mitochondria in UVB-treated cells was attenuated by molecular collagen I-coating. Interestingly, molecular collagen I rescued the loss of mitochondrial biogenesis in cells treated with UVB. Loss of PINK1/parkin-mediated mitophagy was dominant for the accumulation of dysfunctional mitochondria after UVB irradiation. Of note, cells cultured on molecular collagen I-precoated plates exhibited reserved mitophagy after UVB irradiation, as reflected by the enhanced protein level of PINK1/parkin, increased mitochondrial ubiquitin and the co-localization of lysosomes and mitochondria. Moreover, in UVB-treated cells, inhibiting mitophagy by Cyclosporin A, or by silencing PINK1 or parkin, disturbed the resolution of mitochondrial stress and reduced the protective effect of molecular collagen I, indicating that mitophagy is pivotal for the protection of collagen I against UVB damage in keratinocytes HaCaT. Collectively, this study reveals an unexpected protective role of collagen I, which facilitates mitophagy to rescue cells under UVB irradiation, providing a new direction for clinical application of collagen products.

Mitochondrial stress: a key role of neuroinflammation in stroke

Stroke is a clinical syndrome characterized by an acute, focal neurological deficit, primarily caused by the occlusion or rupture of cerebral blood vessels. In stroke, neuroinflammation emerges as a pivotal event contributing to neuronal cell death. The occurrence and progression of neuroinflammation entail intricate processes, prominently featuring mitochondrial dysfunction and adaptive responses. Mitochondria, a double membrane-bound organelle are recognized as the "energy workshop" of the body. Brain is particularly vulnerable to mitochondrial disturbances due to its high energy demands from mitochondria-related energy production. The interplay between mitochondria and neuroinflammation plays a significant role in the pathogenesis of stroke. The biological and pathological consequences resulting from mitochondrial stress have substantial implications for cerebral function. Mitochondrial stress serves as an adaptive mechanism aimed at mitigating the stress induced by the import of misfolded proteins, which occurs in response to stroke. This adaptive response involves a reduction in misfolded protein accumulation and overall protein synthesis. The influence of mitochondrial stress on the pathological state of stroke is underscored by its capacity to interact with neuroinflammation. The impact of mitochondrial stress on neuroinflammation varies according to its severity. Moderate mitochondrial stress can bolster cellular adaptive defenses, enabling cells to better withstand detrimental stressors. In contrast, sustained and excessive mitochondrial stress detrimentally affects cellular and tissue integrity. The relationship between neuroinflammation and mitochondrial stress depends on the degree of mitochondrial stress present. Understanding its role in stroke pathogenesis is instrumental in excavating the novel treatment of stroke. This review aims to provide the evaluation of the cross-talk between mitochondrial stress and neuroinflammation within the context of stroke. We aim to reveal how mitochondrial stress affects neuroinflammation environment in stroke.

PINK1 dominated mitochondria associated genes signature predicts abdominal aortic aneurysm with metabolic syndrome

Abdominal aortic aneurysm (AAA) is typically asymptomatic but a devastating cardiovascular disorder, with overall mortality exceeding 80 % once it ruptures. Some patients with AAA may also have comorbid metabolic syndrome (MS), suggesting a potential common underlying pathogenesis. Mitochondrial dysfunction has been reported as a key factor contributing to the deterioration of both AAA and MS. However, the intricate interplay between metabolism and mitochondrial function, both contributing to the development of AAA, has not been thoroughly explored. In this study, we identified candidate genes related to mitochondrial function in AAA and MS. Subsequently, we developed a nomoscore model comprising hub genes (PINK1, ACSL1, CYP27A1, and SLC25A11), identified through the application of two machine learning algorithms, to predict AAA. We observed a marked disparity in immune infiltration profiles between high- and low-nomoscore groups. Furthermore, we confirmed a significant upregulation of the expression of the four hub genes in AAA tissues. Among these, ACSL1 showed relatively higher expression in LPS-treated RAW264.7 cell lines, while CYP27A1 exhibited a notable decrease. Moreover, SLC25A11 displayed a significant upregulation in AngII-treated VSMCs. Conversely, the expression level of PINK1 declined in LPS-stimulated RAW264.7 cell lines but significantly increased in AngII-treated VSMCs. In vivo experiments revealed that the activation of PINK1-mediated mitophagy inhibited the development of AAA in mice. In this current study, we have innovatively identified four mitochondrial function-related genes through integrated bioinformatic analysis. This discovery sheds light on the regulatory mechanisms and unveils promising therapeutic targets for the comorbidity of AAA and MS.

Hollow Cavity CaO2 @Polydopamine Nanocomposites for pH-Responsive Ca2+ -Enhanced Efficient Mild Hyperthermia in the NIR-II Region

Second near-infrared (NIR-II) mild photothermal therapy with higher tissue penetration depth and less damage to healthy tissues is emerging as an attractive antitumor modality, but its therapeutic efficiency is dramatically suppressed by the resistance of heat shock proteins (HSPs). As a widely explored photothermal agent, the application of polydopamine (PDA) in the NIR-II region is hampered by low photothermal conversion efficiency (PCE). Herein, its PCE in the NIR-II region is improved by developing novel hollow cavity CaO2 @PDA nanocomposites through chelation-induced diffusion of inner core Ca2+ to the shell PDA to facilitate multiple reflections of laser in the cavity. Upon pH-responsive degradation of CaO2 , its structure is transformed into a stacked "nano-mesh" with excellent light absorption and an enlarged effective irradiation area. Overloading of Ca2+ ions not only induces downregulation of HSPs but also enhances interference of light on membrane potential, which further aggravate mitochondrial dysfunction and reduce the thermotolerance of tumor cells, promoting efficient mild hyperthermia of PDA in the NIR-II region.

Mitochondrial transfer - a novel promising approach for the treatment of metabolic diseases

Metabolic disorders remain a major global health concern in the 21st century, with increasing incidence and prevalence. Mitochondria play a critical role in cellular energy production, calcium homeostasis, signal transduction, and apoptosis. Under physiological conditions, mitochondrial transfer plays a crucial role in tissue homeostasis and development. Mitochondrial dysfunction has been implicated in the pathogenesis of metabolic disorders. Numerous studies have demonstrated that mitochondria can be transferred from stem cells to pathologically injured cells, leading to mitochondrial functional restoration. Compared to cell therapy, mitochondrial transplantation has lower immunogenicity, making exogenous transplantation of healthy mitochondria a promising therapeutic approach for treating diseases, particularly metabolic disorders. This review summarizes the association between metabolic disorders and mitochondria, the mechanisms of mitochondrial transfer, and the therapeutic potential of mitochondrial transfer for metabolic disorders. We hope this review provides novel insights into targeted mitochondrial therapy for metabolic disorders.

The Gut-Brain Axis in Alzheimer's and Parkinson's Diseases: The Catalytic Role of Mitochondria

Accumulating evidence suggests that gut inflammation is implicated in neuroinflammation in Alzheimer's and Parkinson's diseases. Despite the numerous connections it remains unclear how the gut and the brain communicate and whether gut dysbiosis is the cause or consequence of these pathologies. Importantly, several reports highlight the importance of mitochondria in the gut-brain axis, as well as in mechanisms like gut epithelium self-renewal, differentiation, and homeostasis. Herein we comprehensively address the important role of mitochondria as a cellular hub in infection and inflammation and as a link between inflammation and neurodegeneration in the gut-brain axis. The role of mitochondria in gut homeostasis and as well the crosstalk between mitochondria and gut microbiota is discussed. Significantly, we also review studies highlighting how gut microbiota can ultimately affect the central nervous system. Overall, this review summarizes novel findings regarding this cross-talk where the mitochondria has a main role in the pathophysiology of both Alzheimer's and Parkinson's disease strengthen by cellular, animal and clinical studies.

Peptide Power: Mechanistic Insights into the Effect of Mitochondria-Targeted Tetrapeptides on Membrane Electrostatics from Molecular Simulations

Mitochondrial dysfunction is implicated in nine of the ten leading causes of death in the US, yet there are no FDA-approved therapeutics to treat it. Synthetic mitochondria-targeted peptides (MTPs), including the lead compound SS-31, offer promise, as they have been shown to restore healthy mitochondrial function and treat a variety of common diseases. At the cellular level, research has shown that MTPs accumulate strongly at the inner mitochondrial membrane (IMM), slow energy sinks (e.g., proton leaks), and improve ATP production. Modulation of electrostatic fields around the IMM has been implicated as a key aspect in the mechanism of action (MoA) of these peptides; however, molecular and mechanistic details have remained elusive. In this study, we employed all-atom molecular dynamics simulations (MD) to investigate the interactions of four MTPs with lipid bilayers and calculate their effect on structural and electrostatic properties. In agreement with previous experimental findings, we observed the modulation of the membrane surface and dipole potentials by MTPs. The simulations reveal that the MTPs achieve a reduction in the dipole potential by acting to disorder both lipid head groups and water layers proximal to the bilayer surface. We also find that MTPs decrease the bilayer thickness and increase the membrane's capacitance. These changes suggest that MTPs may enhance how much potential energy can be stored across the IMM at a given transmembrane potential difference. The MTPs also displace cations away from the bilayer surface, modulating the surface potential and offering an alternative mechanism for how these MTPs reduce mitochondrial energy sinks like proton leaks and mitigate Ca2+ accumulation stress. In conclusion, this study highlights the therapeutic potential of MTPs and underlines how interactions of MTPs with lipid bilayers serve as a fundamental component of their MoA.

Interaction between mitochondria and microbiota modulating cellular metabolism in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a prototypic complex disease in the gastrointestinal tract that has been increasing in incidence and prevalence in recent decades. Although the precise pathophysiology of IBD remains to be elucidated, a large body of evidence suggests the critical roles of mitochondria and intestinal microbiota in the pathogenesis of IBD. In addition to their contributions to the disease, both mitochondria and gut microbes may interact with each other and modulate disease-causing cell activities. Therefore, we hypothesize that dissecting this unique interaction may help to identify novel pathways involved in IBD, which will further contribute to discovering new therapeutic approaches to the disease. As poorly treated IBD significantly affects the quality of life of patients and is associated with risks and complications, successful treatment is crucial. In this review, we stratify previously reported experimental and clinical observations of the role of mitochondria and intestinal microbiota in IBD. Additionally, we review the intercommunication between mitochondria, and the intestinal microbiome in patients with IBD is reviewed along with the potential mediators for these interactions. We specifically focus on their roles in cellular metabolism in intestinal epithelial cells and immune cells. To this end, we propose a potential therapeutic intervention strategy for IBD.

Association with cationized gelatin nanospheres enhances cell internalization of mitochondria efficiency

The objective of this study is to confirm the methodological feasibility of cationized gelatin nanospheres (cGNS) to enhance the internalization efficiency of mitochondria (Mt) isolated to cells for their increasing functions. The cGNS were simply associated on the surface of Mt by the electrostatic interaction. Different sizes of cGNS were used to allow Mt to associate on the Mt surface (Mt-cGNS). As a control, cationized gelatin (cG) was used to modify the Mt surface (Mt-cG). The Mt-cG and Mt-cGNS prepared were cultured with H9c2 cells to examine their internalization. The internalization efficiency significantly increased by utilizing cGNS. However, there was no significant difference in the internalization efficiency among cGNS with different sizes. After incubation of Mt, Mt-cG, and Mt-cGNS, the superoxide amount and ATP generation were evaluated. Significantly lower superoxide amount and higher ATP amount were observed for the Mt-cGNS group compared with those of non-modified Mt group. It is conceivable that cGNS enhance the cellular internalization of Mt, leading to an improve mitochondrial functions in the recipient cells. In conclusion, cGNS are promising to improve the efficacy in mitochondria internalization.