Regulation Of Mitochondrial Function Research Articles

Deprivation of methionine inhibits osteosarcoma growth and metastasis via C1orf112-mediated regulation of mitochondrial functions

Osteosarcoma is a malignant bone tumor that primarily inflicts the youth. It often metastasizes to the lungs after chemotherapy failure, which eventually shortens patients’ lives. Thus, there is a dire clinical need to develop a novel therapy to tackle osteosarcoma metastasis. Methionine dependence is a special metabolic characteristic of most malignant tumor cells that may offer a target pathway for such therapy. Herein, we demonstrated that methionine deficiency restricted the growth and metastasis of cultured human osteosarcoma cells. A genetically engineered Salmonella, SGN1, capable of overexpressing an L-methioninase and hydrolyzing methionine led to significant reduction of methionine and S-adenosyl-methionine (SAM) specifically in tumor tissues, drastically restricted the growth and metastasis in subcutaneous xenograft, orthotopic, and tail vein-injected metastatic models, and prolonged the survival of the model animals. SGN1 also sharply suppressed the growth of patient-derived organoid and xenograft. Methionine restriction in the osteosarcoma cells initiated severe mitochondrial dysfunction, as evident in the dysregulated gene expression of respiratory chains, increased mitochondrial ROS generation, reduced ATP production, decreased basal and maximum respiration, and damaged mitochondrial membrane potential. Transcriptomic and molecular analysis revealed the reduction of C1orf112 expression as a primary mechanism underlies methionine deprivation-initiated suppression on the growth and metastasis as well as mitochondrial functions. Collectively, our findings unraveled a molecular linkage between methionine restriction, mitochondrial function, and osteosarcoma growth and metastasis. A pharmacological agent, such as SGN1, that can achieve tumor specific deprivation of methionine may represent a promising modality against the metastasis of osteosarcoma and potentially other types of sarcomas as well.

Regulation of mitochondrial function by FOXOs in ischemic stroke and Alzheimer’s disease

Transcriptional control is a pivotal mechanism governing various cellular processes. FOXO proteins, a subgroup of the forkhead family of transcription factors, play a key role in determining cell fate. The localization and function of FOXO proteins are regulated by post-translational modifications to control target gene expression, with a pronounced impact on various aspects of mitochondrial function, including mitochondrial dynamics, biogenesis, and quality control. Mitochondria stand out as the primary target of FOXO transcription factors, which recruit downstream signaling factors to govern mitochondrial processes. Essential signaling pathways are modulated by FOXOs, exemplified by their regulation of mitochondrial biogenesis through SIRT1-Pgc1a and NRF1-TFAM, as well as their influence on mitochondrial dynamics involving Mfn1, Mfn2, Drp1, and Fis1. Furthermore, FOXOs demonstrate the ability to upregulate and downregulate genes that serve as modulators in oxidative and apoptosis cascades. The functional role of FOXO proteins is highly context-dependent, varying with cell type, organ, and specific FOXO isoform. Notably, FOXOs emerge as prominent players in various pathological conditions, including ischemic conditions, neurodegenerative diseases, cancer, and metabolic disorders. Unraveling the complex role of FOXOs in mammalian cell pathology positions them as promising therapeutic targets receptive to pharmacological treatment. This review aims to provide insights into the intricate roles of FOXOs in mitochondria, illuminating their potential as therapeutic targets amenable to pharmacological intervention in diverse pathological contexts, particularly in ischemic stroke and Alzheimer’s disease.

Na/K-ATPase α1/Src Signaling Regulates Mitochondrial Metabolic Function and ROS Production in Human iPSC-derived Cardiomyocytes

Through an isoform specific mechanism, the Na/K-ATPase (NKA) α1 polypeptide-mediated regulation of Src kinase has emerged as a novel regulator of mitochondrial function in various cell types. Mitochondrial metabolism ensures adequate myocardial performance and adaptation to physiological demand. It is also a critical cellular determinant of cardiac repair and remodeling. To investigate the importance of the proposed NKA/Src regulatory signaling on cardiac mitochondrial metabolic function independently from the classic Na/K-ATPase enzymatic function, we used a gene targeting approach in cardiomyocytes. Human induced pluripotent stem cells (hiPSC) expressing a Src-signaling null mutant (A420P) form of NKA α1 were generated using CRISPR/Cas9-mediated genome editing. NKA isoform protein expression and enzymatic activity remained unchanged. However, baseline levels of Src and ERK1/2 phosphorylation were decreased by 55% and 80%, respectively in the A420P hiPSC (n=3, p<0.05). Both the WT and A420P hiPSC differentiated into cardiomyocytes (iCM) as assessed by morphology, spontaneous cell contraction, marker gene expression, and subcellular striations. Cell metabolism assessed by Seahorse extracellular flux analysis revealed significant reductions in basal and maximal rates of mitochondrial respiration (50%), spare respiratory capacity (50%), ATP production (60%), and coupling effciency (20%) (n=4, p<0.05). ROS production was monitored in live cells by measuring the oxidation of the CM-H2DCFDA dye using a fluorescence microscope. The slope of the ROS production rate curve was dramatically reduced in A420P iCM (80%, n=3, p<0.05). Protein carbonylation levels, analyzed by ELISA as markers of oxidative damage, were also decreased in A420P iCM (n=4, p<0.05). Taken together, these data provide genetic evidence for a role of NKA α1/Src in the tonic stimulation of basal mitochondrial metabolism and ROS production in human cardiac myocytes. This has potential significance in cardiometabolic diseases and suggests that targeting the NKA α1/Src signaling axis may offer a novel approach to address mitochondrial dysfunction. NIH Grant R15 HL145666, NIH Grant P20GM103434 to the West Virginia IDeA Network of Biomedical Research Excellence, and American Heart Association Postdoctoral Fellowship — 22POST917776 — to Marco T. Pessoa. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acyl-CoA synthetase 4 modulates mitochondrial function in breast cancer cells

Mitochondria are dynamic organelles that respond to cellular stress through changes in global mass, interconnection, and subcellular location. As mitochondria play an important role in tumor development and progression, alterations in energy metabolism allow tumor cells to survive and spread even in challenging conditions. Alterations in mitochondrial bioenergetics have been recently proposed as a hallmark of cancer, and positive regulation of lipid metabolism constitutes one of the most common metabolic changes observed in tumor cells. Acyl-CoA synthetase 4 (ACSL4) is an enzyme catalyzing the activation of long chain polyunsaturated fatty acids with a strong substrate preference for arachidonic acid (AA). High ACSL4 expression has been related to aggressive cancer phenotypes, including breast cancer, and its overexpression has been shown to positively regulate the mammalian Target of Rapamycin (mTOR) pathway, involved in the regulation of mitochondrial metabolism genes. However, little is known about the role of ACSL4 in the regulation of mitochondrial function and metabolism in cancer cells. In this context, our objective was to study whether mitochondrial function and metabolism, processes usually altered in tumors, are modulated by ACSL4 in breast cancer cells. Using ACSL4 overexpression in MCF-7 cells, we demonstrate that this enzyme can increase the mRNA and protein levels of essential mitochondrial regulatory proteins such as nuclear respiratory factor 1 (NRF-1), voltage-dependent anion channel 1 (VDAC1) and respiratory chain Complex III. Furthermore, respiratory parameters analysis revealed an increase in oxygen consumption rate (OCR) and in spare respiratory capacity (SRC), among others. ACSL4 knockdown in MDA-MB-231 cells led to the decrease in OCR and in SCR, supporting the role of ACSL4 in the regulation of mitochondrial bioenergetics. Moreover, ACSL4 overexpression induced an increase in glycolytic function, in keeping with an increase in mitochondrial respiratory activity. Finally, there was a decrease in mitochondrial mass detected in cells that overexpressed ACSL4, while the knockdown of ACSL4 expression in MDA-MB-231 cells showed the opposite effect. Altogether, these results unveil the role of ACSL4 in mitochondrial function and metabolism and expand the knowledge of ACSL4 participation in pathological processes such as breast cancer.

Characterizing MetALD in a Nonhuman Primate Model using High Fat and Sucrose Diet and Chronic Binge Alcohol Administration

Mechanisms leading to metabolic and alcohol associated liver disease (MetALD) are not clearly delineated. This study examined the differential regulation of markers of hepatic mitochondrial function in nonhuman primates fed a high fat/high sucrose (HFSD) and administered chronic binge alcohol (CBA) or vehicle as compared to control-fed animals. We hypothesized that markers of hepatic dysregulation due to HFSD will be further altered by the combination of CBA/HFSD. Eight rhesus macaques were fed HFSD (27% sucrose and 42% fat, by kcal) with n=4 receiving vehicle and n=4 receiving 13-14g/kg/wk of ethanol through a gastric catheter. Rhesus macaques fed standard primate chow were used as reference controls (n=4-6). Liver RNA was isolated for determining expression of genes regulating mitochondrial biogenesis and function using RT-qPCR. Results were analyzed using one-way ANOVA and post-hoc pairwise multiple comparisons were performed using Tukey’s method, with alpha set to 0.05. Expression of inflammatory genes was significantly altered across the groups (p<0.05). HFSD increased tumor necrosis factor alpha (p=0.01), interleukin 1-beta (p=0.04), cluster of differentiation 38 (p=0.01), and transforming growth factor beta (p=0.01) expression compared to control. Both HFSD and CBA/HFSD increased interleukin-10 compared to control (p=0.02, p=0.03). Gene expression of mitochondrial function and oxidative stress regulators were significantly altered across the groups (p<0.05). CBA/HFSD decreased expression of peroxisome proliferator-activated receptor-gamma coactivator-1 beta (p=0.04) and nuclear respiratory factor 2 (p=0.04) compared to control. Both HFSD and CBA/HFSD decreased peroxisome proliferator-activated receptor alpha expression compared to control (p=0.01, 0.01). HFSD decreased superoxide dismutase 2 (SOD2) expression compared to control (p=0.01) and increased uncoupling protein 2 (p=0.01). SOD2 expression was increased only in CBA/HFSD compared to HFSD (p=0.01). These results reveal marked HFSD-mediated increases in markers of inflammation and CBA/HFSD-mediated changes in markers of mitochondrial function regulation and oxidative stress regulation. These findings suggest a greater impact of calorie-dense diets than CBA on hepatic inflammation and a combined impact of CBA and HFSD on mitochondrial regulation. Ongoing studies will examine oxidative phosphorylation complex protein activities and expression to elucidate and integrate HFSD or CBA mediated changes in hepatic bioenergetic capacity. Supported by F30AA030910, P60AA009803, and T32AA007577. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Selected humanization of yeast U1 snRNP leads to global suppression of pre-mRNA splicing and mitochondrial dysfunction in the budding yeast.

The recognition of 5' splice site (5' ss) is one of the earliest steps of pre-mRNA splicing. To better understand the mechanism and regulation of 5' ss recognition, we selectively humanized components of the yeast U1 snRNP to reveal the function of these components in 5' ss recognition and splicing. We targeted U1C and Luc7, two proteins that interact with and stabilize the yeast U1 (yU1) snRNA and the 5' ss RNA duplex. We replaced the Zinc-Finger (ZnF) domain of yU1C with its human counterpart, which resulted in a cold-sensitive growth phenotype and moderate splicing defects. We next added an auxin-inducible degron to yLuc7 protein (to mimic the lack of Luc7Ls in human U1 snRNP) and found that Luc7-depleted yU1 snRNP resulted in the concomitant loss of PRP40 and Snu71 (two other essential yeast U1 snRNP proteins), and further biochemical analyses suggest a model of how these three proteins interact with each other in the U1 snRNP. The loss of these proteins resulted in a significant growth retardation accompanied by a global suppression of pre-mRNA splicing. The splicing suppression led to mitochondrial dysfunction as revealed by a release of Fe2+ into the growth medium and an induction of mitochondrial reactive oxygen species. Together, these observations indicate that the human U1C ZnF can substitute that of yeast, Luc7 is essential for the incorporation of the Luc7-Prp40-Snu71 trimer into yeast U1 snRNP, and splicing plays a major role in the regulation of mitochondrial function in yeast.

Modulating Nitric Oxide: Implications for Cytotoxicity and Cytoprotection.

Despite the significant progress in the fields of biology, physiology, molecular medicine, and pharmacology; the designation of the properties of nitrogen monoxide in the regulation of life-supporting functions of the organism; and numerous works devoted to this molecule, there are still many open questions in this field. It is widely accepted that nitric oxide (•NO) is a unique molecule that, despite its extremely simple structure, has a wide range of functions in the body, including the cardiovascular system, the central nervous system (CNS), reproduction, the endocrine system, respiration, digestion, etc. Here, we systematize the properties of •NO, contributing in conditions of physiological norms, as well as in various pathological processes, to the mechanisms of cytoprotection and cytodestruction. Current experimental and clinical studies are contradictory in describing the role of •NO in the pathogenesis of many diseases of the cardiovascular system and CNS. We describe the mechanisms of cytoprotective action of •NO associated with the regulation of the expression of antiapoptotic and chaperone proteins and the regulation of mitochondrial function. The most prominent mechanisms of cytodestruction-the initiation of nitrosative and oxidative stresses, the production of reactive oxygen and nitrogen species, and participation in apoptosis and mitosis. The role of •NO in the formation of endothelial and mitochondrial dysfunction is also considered. Moreover, we focus on the various ways of pharmacological modulation in the nitroxidergic system that allow for a decrease in the cytodestructive mechanisms of •NO and increase cytoprotective ones.

Progress of Mitochondrial Function Regulation in Cardiac Regeneration.

Heart failure and myocardial infarction, global health concerns, stem from limited cardiac regeneration post-injury. Myocardial infarction, typically caused by coronary artery blockage, leads to cardiac muscle cell damage, progressing to heart failure. Addressing the adult heart's minimal self-repair capability is crucial, highlighting cardiac regeneration research's importance. Studies reveal a metabolic shift from anaerobic glycolysis to oxidative phosphorylation in neonates as a key factor in impaired cardiac regeneration, with mitochondria being central. The heart's high energy demands rely on a robust mitochondrial network, essential for cellular energy, cardiac health, and regenerative capacity. Mitochondria's influence extends to redox balance regulation, signaling molecule interactions, and apoptosis. Changes in mitochondrial morphology and quantity also impact cardiac cell regeneration. This article reviews mitochondria's multifaceted role in cardiac regeneration, particularly in myocardial infarction and heart failure models. Understanding mitochondrial function in cardiac regeneration aims to enhance myocardial infarction and heart failure treatment methods and insights.

Mitochondrial Kinase Signaling for Cardioprotection.

Myocardial ischemia/reperfusion injury is reduced by cardioprotective adaptations such as local or remote ischemic conditioning. The cardioprotective stimuli activate signaling cascades, which converge on mitochondria and maintain the function of the organelles, which is critical for cell survival. The signaling cascades include not only extracellular molecules that activate sarcolemmal receptor-dependent or -independent protein kinases that signal at the plasma membrane or in the cytosol, but also involve kinases, which are located to or within mitochondria, phosphorylate mitochondrial target proteins, and thereby modify, e.g., respiration, the generation of reactive oxygen species, calcium handling, mitochondrial dynamics, mitophagy, or apoptosis. In the present review, we give a personal and opinionated overview of selected protein kinases, localized to/within myocardial mitochondria, and summarize the available data on their role in myocardial ischemia/reperfusion injury and protection from it. We highlight the regulation of mitochondrial function by these mitochondrial protein kinases.

AAV-mediated upregulation of VDAC1 rescues the mitochondrial respiration and sirtuins expression in a SOD1 mouse model of inherited ALS.

Mitochondrial dysfunction represents one of the most common molecular hallmarks of both sporadic and familial forms of amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder caused by the selective degeneration and death of motor neurons. The accumulation of misfolded proteins on and within mitochondria, as observed for SOD1 G93A mutant, correlates with a drastic reduction of mitochondrial respiration and the inhibition of metabolites exchanges, including ADP/ATP and NAD+/NADH, across the Voltage-Dependent Anion-selective Channel 1 (VDAC1), the most abundant channel protein of the outer mitochondrial membrane. Here, we show that the AAV-mediated upregulation of VDAC1 in the spinal cord of transgenic mice expressing SOD1 G93A completely rescues the mitochondrial respiratory profile. This correlates with the increased activity and levels of key regulators of mitochondrial functions and maintenance, namely the respiratory chain Complex I and the sirtuins (Sirt), especially Sirt3. Furthermore, the selective increase of these mitochondrial proteins is associated with an increase in Tom20 levels, the receptor subunit of the TOM complex. Overall, our results indicate that the overexpression of VDAC1 has beneficial effects on ALS-affected tissue by stabilizing the Complex I-Sirt3 axis.

Linking triphenylphosphonium cation to a bicyclic hydroquinone improves their antiplatelet effect via the regulation of mitochondrial function

Platelets are the critical target for preventing and treating pathological thrombus formation. However, despite current antiplatelet therapy, cardiovascular mortality remains high, and cardiovascular events continue in prescribed patients. In this study, first results were obtained with ortho-carbonyl hydroquinones as antiplatelet agents; we found that linking triphenylphosphonium cation to a bicyclic ortho-carbonyl hydroquinone moiety by a short alkyl chain significantly improved their antiplatelet effect by affecting the mitochondrial functioning. The mechanism of action involves uncoupling OXPHOS, which leads to an increase in mitochondrial ROS production and a decrease in the mitochondrial membrane potential and OCR. This alteration disrupts the energy production by mitochondrial function necessary for the platelet activation process. These effects are responsive to the complete structure of the compounds and not to isolated parts of the compounds tested. The results obtained in this research can be used as the basis for developing new antiplatelet agents that target mitochondria.

Gene Expression Profiling Reveals Fundamental Sex-Specific Differences in SIRT3-Mediated Redox and Metabolic Signaling in Mouse Embryonic Fibroblasts.

Sirt-3 is an important regulator of mitochondrial function and cellular energy homeostasis, whose function is associated with aging and various pathologies such as Alzheimer's disease, Parkinson's disease, cardiovascular diseases, and cancers. Many of these conditions show differences in incidence, onset, and progression between the sexes. In search of hormone-independent, sex-specific roles of Sirt-3, we performed mRNA sequencing in male and female Sirt-3 WT and KO mouse embryonic fibroblasts (MEFs). The aim of this study was to investigate the sex-specific cellular responses to the loss of Sirt-3. By comparing WT and KO MEF of both sexes, the differences in global gene expression patterns as well as in metabolic and stress responses associated with the loss of Sirt-3 have been elucidated. Significant differences in the activities of basal metabolic pathways were found both between genotypes and between sexes. In-depth pathway analysis of metabolic pathways revealed several important sex-specific phenomena. Male cells mount an adaptive Hif-1a response, shifting their metabolism toward glycolysis and energy production from fatty acids. Furthermore, the loss of Sirt-3 in male MEFs leads to mitochondrial and endoplasmic reticulum stress. Since Sirt-3 knock-out is permanent, male cells are forced to function in a state of persistent oxidative and metabolic stress. Female MEFs are able to at least partially compensate for the loss of Sirt-3 by a higher expression of antioxidant enzymes. The activation of neither Hif-1a, mitochondrial stress response, nor oxidative stress response was observed in female cells lacking Sirt-3. These findings emphasize the sex-specific role of Sirt-3, which should be considered in future research.

Hippocampal Pyk2 regulates specific social skills: Implications for schizophrenia

Pyk2 has been shown previously to be involved in several psychological and cognitive alterations related to stress, Huntington's disease, and Alzheimer's disease. All these disorders are accompanied by different types of impairments in sociability, which has recently been linked to improper mitochondrial function. We hypothesize that Pyk2, which regulates mitochondria, could be associated with the regulation of mitochondrial dynamics and social skills. In the present manuscript, we report that a reduction of Pyk2 levels in mouse pyramidal neurons of the hippocampus decreased social dominance and aggressivity. Furthermore, social interactions induced robust Pyk2-dependent hippocampal changes in several oxidative phosphorylation complexes. We also observed that Pyk2 levels were increased in the CA1 pyramidal neurons of schizophrenic subjects, occurring alongside changes in different direct and indirect regulators of mitochondrial function including DISC1 and Grp75. Accordingly, overexpressing Pyk2 in hippocampal CA1 pyramidal cells mimicked some specific schizophrenia-like social behaviors in mice. In summary, our results indicate that Pyk2 might play a role in regulating specific social skills likely via mitochondrial dynamics and that there might be a link between Pyk2 levels in hippocampal neurons and social disturbances in schizophrenia.

Oxidative Stress in Spinocerebellar Ataxia Type 3 and Its Attenuation by Herbal Remedies in Traditional Chinese Medicine: A Systematic Review.

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder that gives rise to motor incoordination and progressive functional disabilities. Although pharmacological interventions have revealed promising prospects in the management of SCA3, adverse effects may become unbearable. The use of herbal remedies in traditional Chinese medicine (TCM) may serve as potential alternative medicines to delay the progression of the disease. This systematic review is intended to identify, appraise, and summarize the findings of studies pertaining to the therapeutic roles of herbal remedies in TCM targeting oxidative stress in the management of SCA3. A literature search for relevant articles published from 1 January 2013 to 30 June 2023 in three databases, namely PubMed, Web of Science, and Scopus, was carried out according to the procedures of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A total of ten preclinical studies met the inclusion criteria of the systematic review. We recognized the therapeutic potential of Brassica napus, Codonopsis pilosula, Curcuma sp., Gardenia jasminoides, Gastrodia elata, Ginkgo biloba, Glycyrrhiza inflata, Hericium erinaceus, Hyptis sp., Paeonia lactiflora, Panax ginseng, Poria cocos, Pueraria lobata, Rehmannia glutinosa, and Scrophularia ningpoensis. We identified the types of preclinical models expressing polyglutamine (polyQ) expanded mutant protein (mATXN3), inducers of oxidative stress that mimic the SCA3 pathogenesis, and effective doses of the herbal remedies. The modes of action contributing to the attenuation of oxidative stress are activation of antioxidant pathways, ubiquitin-proteasome system and autophagy, regulation of apoptosis, proinflammatory signaling pathway and chaperones, regulation of mitochondrial function and biogenesis, and restoration of neurotransmission and synaptic plasticity. In conclusion, herbal remedies in TCM may possibly delay the progression of SCA3, therefore providing justification for clinical trials.

Vitamin D Protects Against Cardiac Hypertrophy Through the Regulation of Mitochondrial Function in Aging Rats.

Cardiac aging is defined as mitochondrial dysfunction of the heart. Vitamin D (VitD) is an effective agent in ameliorating cardiovascular disorders. In this study, we indicated the protective effects of VitD against cardiac aging. Male Wistar rats were randomly divided into four groups: control (CONT), D-galactose (D-GAL): aged rats induced by D-GAL, D-GAL + Ethanol: aged rats treated with ethanol, and D-GAL + VitD aged rats treated with VitD. Aging was induced by D-GAL at 150 mg/kg via intraperitoneal injection for 8 weeks. Aged rats were treated with VitD (D-GAL + VitD) by gavage for 8 weeks. The serum samples were used to evaluate biochemical factors, and heart tissues were assessed to determine oxidative stress and gene expression. The D-GAL rats exhibited cardiac hypertrophy, which was associated with decreased antioxidant enzyme activity, enhanced oxidative marker, and changes in the expression of mitochondrial genes in comparison with the control rats. Co-treatment with VitD ameliorated all these changes. In conclusion, VitD could protect the heart against D-GAL-induced aging via enhancing antioxidant effects, and the expression of mitochondrial genes.

The Roles of Cystatin B in the Brain and Pathophysiological Mechanisms of Progressive Myoclonic Epilepsy Type 1.

Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessive disorder, also known as Unverricht-Lundborg disease (ULD). EPM1 patients suffer from photo-sensitive seizures, stimulus-sensitive myoclonus, nocturnal myoclonic seizures, ataxia and dysarthria. In addition, cerebral ataxia and impaired GABAergic inhibition are typically present. EPM1 is caused by mutations in the Cystatin B gene (CSTB). The CSTB protein functions as an intracellular thiol protease inhibitor and inhibits Cathepsin function. It also plays a crucial role in brain development and regulates various functions in neurons beyond maintaining cellular proteostasis. These include controlling cell proliferation and differentiation, synaptic functions and protection against oxidative stress, likely through regulation of mitochondrial function. Depending on the differentiation stage and status of neurons, the protein localizes either to the cytoplasm, nucleus, lysosomes or mitochondria. Further, CSTB can also be secreted to the extracellular matrix for interneuron rearrangement and migration. In this review, we will review the various functions of CSTB in the brain and discuss the putative pathophysiological mechanism underlying EPM1.

Glutamine Metabolism Promotes Renal Fibrosis through Regulation of Mitochondrial Energy Generation and Mitochondrial Fission.

Fibroblast activation and proliferation is an essential phase in the progression of renal fibrosis. Despite the recognized significance of glutamine metabolism in cellular growth and proliferation, its precise pathophysiological relevance in renal fibrosis remains uncertain. Therefore, this study aims to investigate the involvement of glutamine metabolism in fibroblast activation and its possible mechanism. Our findings highlight the importance of glutamine metabolism in fibroblast activation and reveal that patients with severe fibrosis exhibit elevated serum glutamine levels and increased expression of kidney glutamine synthetase. Furthermore, the deprivation of glutamine metabolism in vitro and in vivo could inhibit fibroblast activation, thereby ameliorating renal fibrosis. It was also detected that glutamine metabolism is crucial for maintaining mitochondrial function and morphology. These effects may partially depend on the metabolic intermediate α-ketoglutaric acid. Moreover, glutamine deprivation led to upregulated mitochondrial fission in fibroblasts and the activation of the mammalian target of rapamycin / mitochondrial fission process 1 / dynamin-related protein 1 pathway. Thus, these results provide compelling evidence that the modulation of glutamine metabolism initiates the regulation of mitochondrial function, thereby facilitating the progression of renal fibrosis. Consequently, targeting glutamine metabolism emerges as a novel and promising avenue for therapeutic intervention and prevention of renal fibrosis.

Effect of Talatisamine and its Derivate 14-O-Benzoyltalatisamine on Functional State of Rat Liver and Heart Mitochondria

Dysfunction of the mitochondria of various tissues causes the development of most pathological processes, including ischemia. In recent years, great attention has been paid to the use of plant biologically active substances in the prevention and treatment of pathological processes related to mitochondrial dysfunction. This is very relevant in relation to ischemic diseases and is of scientific and practical importance in the search for new pharmacological agents that correct the functions of damaged mitochondria for their treatment. The mitochondrial permeability transition pore (mPTP) actively participates in the regulation of mitochondrial functions, in the development of various pathological conditions and, at the same time, targets for various drugs and some biologically active substances. In vitro experiments evaluated the effects of alkaloids talatisamine and 14-O-benzoyltalatisamine on rat liver and heart Ca2+-dependent mPTP and lipid peroxidation (LPO) induced by Fe2+/ascorbate system. The investigated diterpenealkaloids inhibited the opening of the Ca2+-dependent mPTP in the membranes of rat liver and heart mitochondria. It was found that 14-O-benzoyltalatizamine inhibits the Ca2+-dependent conductance pore of rat liver and heart mitochondria more strongly than talatisamine. To compare the effects of 14-O-benzoyltalatisamine on rat liver and heart mPTP, concentrations from 1 μM to 200 μM were investigated. At these concentrations, liver mPTP was reliably inhibited by 10% to 81% and heart mPTP by 3.6% to 71.5% relative to control. The high sensitivity of diterpene alkaloids to the Ca2+-dependent permeability transition pore of liver mitochondria compared to heart mitochondria indicates their tissue specificity. The investigated alkaloids exhibited antioxidant properties by inhibiting Fe2+/ascorbate-induced mitochondrial suppression (LPO process) and MDA formation in membranes. LPO induced by Fe2+/ascorbate system in mitochondrial membranes was more actively inhibited by 14-O-benzoyltalatisamine. According to the results of the research, acylation of the hydroxyl group at the C-14 position of talatisamine by benzoyl chloride caused a rise in molecular activity of the derivative due to the introduction of the benzoyl group.

Valine improves mitochondrial function and protects against oxidative stress.

Among the branched-chain amino acids, leucine and isoleucine have been well studied for their roles in improving mitochondrial function and reducing oxidative stress. However, role of valine in mitochondrial function regulation and oxidative stress management remains elusive. This study investigated valine effect on mitochondrial function and oxidative stress in vitro. Valine increased expression of genes involved in mitochondrial biogenesis and dynamics. It upregulates mitochondrial function at complexes I, II, and IV levels of electron transport chain. Flow cytometry studies revealed, valine reduced oxidative stress by significantly lowering mitochondrial reactive oxygen species and protein expression of 4-hydroxynonenal. Functional role of valine against oxidative stress was analyzed by XFe96 Analyzer. Valine sustained oxidative phosphorylation and improved ATP generation rates during oxidative stress. In conclusion, our findings shed more light on the critical function of valine in protecting mitochondrial function thereby preventing mitochondrial/cellular damage induced by oxidative stress.

New Insights into the LANCL2-ABA Binding Mode towards the Evaluation of New LANCL Agonists.

The lanthionine synthetase C-like (LANCL) proteins include LANCL2, which is expressed in the central nervous system (CNS) and in peripheral tissues. LANCL2 exhibits glutathionylation activity and is involved in the neutralization of reactive electrophiles. Several studies explored LANCL2 activation as a validated pharmacological target for diabetes and inflammatory bowel disease. In this context, LANCL2 was found to bind the natural product abscisic acid (ABA), whose pre-clinical effectiveness in different inflammatory diseases was reported in the literature. More recently, LANCL2 attracted more attention as a valuable resource in the field of neurodegenerative disorders. ABA was found to regulate neuro-inflammation and synaptic plasticity to enhance learning and memory, exhibiting promising neuroprotective effects. Up until now, a limited number of LANCL2 ligands are known; among them, BT-11 is the only compound patented and investigated for its anti-inflammatory properties. To guide the design of novel putative LANCL2 agonists, a computational study including molecular docking and long molecular dynamic (MD) simulations of both ABA and BT-11 was carried out. The results pointed out the main LANCL2 ligand chemical features towards the following virtual screening of a novel putative LANCL2 agonist (AR-42). Biochemical assays on rat H9c2 cardiomyocytes showed a similar, LANCL2-mediated stimulation by BT-11 and by AR-42 of the mitochondrial proton gradient and of the transcriptional activation of the AMPK/PGC-1α/Sirt1 axis, the master regulator of mitochondrial function, effects that are previously observed with ABA. These results may allow the development of LANCL2 agonists for the treatment of mitochondrial dysfunction, a common feature of chronic and degenerative diseases.