Compartmentally scavenging hepatic oxidants through AMPK/SIRT3-PGC1α axis improves mitochondrial biogenesis and glucose catabolism

Effect of N-Acetylcysteine in Mitochondrial Function, Redox Signaling, and Sirtuin 3 Levels in the Heart During Cardiorenal Syndrome Type 4 Development

Type 4 cardiorenal syndrome (CRS-4) is a pathology in which chronic kidney disease (CKD) triggers the development of cardiovascular disease. CKD pathophysiology produces alterations that can affect the bioenergetics of heart mitochondria, causing oxidative stress and reducing antioxidant glutathione (GSH) levels. GSH depletion alters protein function by affecting post-translational modifications such as S-glutathionylation (RS-SG), exacerbating oxidative stress, and mitochondrial dysfunction. On the other hand, N-acetylcysteine (NAC) is an antioxidant GSH precursor that modulates oxidative stress and RS-SG. Moreover, recent studies have found that NAC can activate the Sirtuin 3 (SIRT3) deacetylase in diseases. However, the role of NAC and its effects on mitochondrial function, redox signaling, and SIRT3 modifications in the heart during CRS-4 have not been studied. This study aimed to investigate the role of NAC in mitochondrial function, redox signaling, and SIRT3 in the hearts of animals with CRS-4 at two months of follow-up. Our results showed that the oral administration of NAC (600 mg/kg/day) improved blood pressure and reduced cardiac fibrosis. NACs' protective effect was associated with preserving cardiac mitochondrial bioenergetics and decreasing these organelles' hydrogen peroxide (H2O2) production. Additionally, NAC increased GSH levels in heart mitochondria and regulated the redox state, which coincided with an increase in nicotinamide adenine dinucleotide oxidized (NAD+) levels and a decrease in mitochondrial acetylated lysines. Finally, NAC increased SIRT3 levels and the activity of superoxide dismutase 2 (SOD-2) in the heart. Thus, treatment with NAC decreases mitochondrial alterations, restores redox signaling, and decreases SIRT3 disturbances during CRS-4 through an antioxidant defense mechanism.

New Insights into AMPK, as a Potential Therapeutic Target in Metabolic Dysfunction-Associated Steatotic Liver Disease and Hepatic Fibrosis

AMP-activated protein kinase (AMPK) activators have garnered significant attention for their potential to prevent the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) into liver fibrosis and to fundamentally improve liver function. The broad spectrum of pathways regulated by AMPK activators makes them promising alternatives to conventional liver replacement therapies and the limited pharmacological treatments currently available. In this study, we aim to illustrate the newly detailed multiple mechanisms of MASLD progression based on the multiple-hit hypothesis. This model posits that impaired lipid metabolism, combined with insulin resistance and metabolic imbalance, initiates inflammatory cascades, gut dysbiosis, and the accumulation of toxic metabolites, ultimately promoting fibrosis and accelerating MASLD progression to irreversible hepatocellular carcinoma (HCC). AMPK plays a multifaceted protective role against these pathological conditions by regulating several key downstream signaling pathways. It regulates biological effectors critical to metabolic and inflammatory responses, such as SIRT1, Nrf2, mTOR, and TGF-β, through complex and interrelated mechanisms. Due to these intricate connections, AMPK's role is pivotal in managing metabolic and inflammatory disorders. In this review, we demonstrate the specific roles of AMPK and its related pathways. Several agents directly activate AMPK by binding as agonists, while some others indirectly activate AMPK by modulating upstream molecules, including adiponectin, LKB1, and the AMP: ATP ratio. As AMPK activators can target each stage of MASLD progression, the development of AMPK activators offers immense potential to expand therapeutic strategies for liver diseases such as MASH, MASLD, and liver fibrosis.

Role of mitochondria in reno-cardiac diseases: A study of bioenergetics, biogenesis, and GSH signaling in disease transition

Acute kidney injury (AKI) and chronic kidney disease (CKD) are global health burdens with rising prevalence. Their bidirectional relationship with cardiovascular dysfunction, manifesting as cardio-renal syndromes (CRS) types 3 and 4, underscores the interconnectedness and interdependence of these vital organ systems. Both the kidney and the heart are critically reliant on mitochondrial function. This organelle is currently recognized as a hub in signaling pathways, with emphasis on the redox regulation mediated by glutathione (GSH). Mitochondrial dysfunction, including impaired bioenergetics, redox, and biogenesis pathways, are central to the progression of AKI to CKD and the development of CRS type 3 and 4. This review delves into the metabolic reprogramming and mitochondrial redox signaling and biogenesis alterations in AKI, CKD, and CRS. We examine the pathophysiological mechanisms involving GSH redox signaling and the AMP-activated protein kinase (AMPK)-sirtuin (SIRT)1/3-peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α) axis in these conditions. Additionally, we explore the therapeutic potential of GSH synthesis inducers in mitigating these mitochondrial dysfunctions, as well as their effects on inflammation and the progression of CKD and CRS types 3 and 4.

Peroxynitrite reduces Treg cell expansion and function by mediating IL-2R nitration and aggravates multiple sclerosis pathogenesis

T-helper 17 cells and regulatory T cells (Treg) are critical regulators in the pathogenesis of multiple sclerosis (MS) but the factors affecting Treg/Th17 balance remains largely unknown. Redox balance is crucial to maintaining immune homeostasis and reducing the severity of MS but the underlying mechanisms are unclear yet. Herein, we tested the hypothesis that peroxynitrite, a representative molecule of reactive nitrogen species (RNS), could inhibit peripheral Treg cells, disrupt Treg/Th17 balance and aggravate MS pathology by inducing nitration of interleukin-2 receptor (IL-2R) and down-regulating RAS/JNK-AP-1 signalling pathway. Experimental autoimmune encephalomyelitis (EAE) mouse model and serum samples of MS patients were used in the study. We found that the increases of 3-nitrotyrosine and IL-2R nitration in Treg cells were coincided with disease severity in the active EAE mice. Mechanistically, peroxynitrite-induced IL-2R nitration down-regulated RAS/JNK signalling pathway, subsequently impairing peripheral Treg expansion and function, increasing Teff infiltration into the central nerve system (CNS), aggravating demyelination and neurological deficits in the EAE mice. Those changes were abolished by peroxynitrite decomposition catalyst (PDC) treatment. Furthermore, transplantation of the PDC-treated-autologous Treg cells from donor EAE mice significantly decreased Th17 cells in both axillary lymph nodes and lumbar spinal cord, and ameliorated the neuropathology of the recipient EAE mice. Those results suggest that peroxynitrite could disrupt peripheral Treg/Th17 balance, and aggravate neuroinflammation and neurological deficit in active EAE/MS pathogenesis. The underlying mechanisms are related to induce the nitration of IL-2R and inhibit the RAS/JNK-AP-1 signalling pathway in Treg cells. The study highlights that targeting peroxynitrite-mediated peripheral IL-2R nitration in Treg cells could be a novel therapeutic strategy to restore Treg/Th17 balance and ameliorate MS/EAE pathogenesis. The study provides valuable insights into potential role of peripheral redox balance in maintaining CNS immune homeostasis.

Molecular crosstalk and putative mechanisms underlying mitochondrial quality control: The hidden link with methylmercury-induced cognitive impairment

Methylmercury (MeHg) is a neurotoxin associated with foetal neurodevelopmental and adult cognitive deficits. Neurons are highly dependent on the tricarboxylic acid cycle and oxidative phosphorylation to produce ATP and meet their high energy demands. Therefore, mitochondrial quality control (MQC) is critical for neuronal homeostasis. While existing studies have generated a wealth of data on the toxicity of MeHg, the complex cascades and molecular pathways governing the mitochondrial network remain to be elucidated. Here, 0.6, 1.2 and 2.4 mg/kg body weight of MeHg were administered intragastrically to pregnant Sprague Dawley rats to model maternal MeHg exposure. The results of the in vivo study revealed that MeHg-treated rats tended to perform more directionless repetitive strategies in the Morris Water Maze and fewer target-orientation strategies than control offspring. Moreover, pathological injury and synaptic toxicity were observed in the hippocampus. Transmission electron microscopy (TEM) demonstrated that the autophagosomes encapsulated damaged mitochondria, while showing a typical mitochondrial fission phenotype, which was supported by the activation of PINK1-dependent key regulators of mitophagy. Moreover, there was upregulation of DRP1 and FIS1. Additionally, MeHg compensation promoted mitochondrial biogenesis, as evidenced by the activation of the mitochondrial PGC1-α-NRF1-TFAM signalling pathway. Notably, SIRT3/AMPK was activated by MeHg, and the expression and activity of p-AMPK, p-LKB1 and SIRT3 were consistently coordinated. Collectively, these findings provide new insights into the potential molecular mechanisms regulating MeHg-induced cognitive deficits through SIRT3/AMPK MQC network coordination.

Cilostazol Attenuates Hepatic Steatosis and Intestinal Disorders in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases in the world, which begins with liver lipid accumulation and is associated with metabolic syndrome. Also, the name chosen to replace NAFLD was metabolic dysfunction-associated steatotic liver disease (MASLD). We performed focused drug screening and found that Cilostazol effectively ameliorated hepatic steatosis and might offer potential for NAFLD treatment. Our aim was to investigate the therapeutic effects of Cilostazol on the glycolipid metabolism and intestinal flora in NAFLD mice and explore the specific mechanism. In this study, 7-week-old male C57BL/6J mice were fed a high-fat diet (HFD) for 8 weeks to induce NAFLD, and then treated with intragastric administration for 12 weeks. The results showed that Cilostazol inhibited liver lipid de novo synthesis by regulating the AMPK-ACC1/SCD1 pathway and inhibited liver gluconeogenesis by the AMPK-PGC1α-G6P/PEPCK pathway. Cilostazol improved the intestinal flora diversity and intestinal microbial composition in the NAFLD mice, and specifically regulated Desulfovibrio and Akkermansia. In addition, Cilostazol increased the level of short-chain fatty acids in the NAFLD mice to a level similar to that in the blank Control group. Cilostazol reduces liver lipid accumulation in NAFLD mice by improving glucose and lipid metabolism disorders and intestinal dysfunction, thereby achieving the purpose of treating NAFLD.

Docosahexaenoic Acid Coordinating with Sodium Selenite Promotes Paraptosis in Colorectal Cancer Cells by Disrupting the Redox Homeostasis and Activating the MAPK Pathway

Tumor cells are characterized by a delicate balance between elevated oxidative stress and enhanced antioxidant capacity. This intricate equilibrium, maintained within a threshold known as redox homeostasis, offers a unique perspective for cancer treatment by modulating reactive oxygen species (ROS) levels beyond cellular tolerability, thereby disrupting this balance. However, currently used chemotherapy drugs require larger doses to increase ROS levels beyond the redox homeostasis threshold, which may cause serious side effects. How to disrupt redox homeostasis in cancer cells more effectively remains a challenge. In this study, we found that sodium selenite and docosahexaenoic acid (DHA), a polyunsaturated fatty acid extracted from marine fish, synergistically induced cytotoxic effects in colorectal cancer (CRC) cells. Physiological doses of DHA simultaneously upregulated oxidation and antioxidant levels within the threshold range without affecting cell viability. However, it rendered the cells more susceptible to reaching the upper limit of the threshold of redox homeostasis, facilitating the elevation of ROS levels beyond the threshold by combining with low doses of sodium selenite, thereby disrupting redox homeostasis and inducing MAPK-mediated paraptosis. This study highlights the synergistic anticancer effects of sodium selenite and DHA, which induce paraptosis by disrupting redox homeostasis in tumor cells. These findings offer a novel strategy for more targeted and less toxic cancer therapies for colorectal cancer treatment.

Macrod1 suppresses diabetic cardiomyopathy via regulating PARP1-NAD+-SIRT3 pathway

Diabetic cardiomyopathy (DCM), one of the most serious long-term consequences of diabetes, is closely associated with oxidative stress, inflammation and apoptosis in the heart. MACRO domain containing 1 (Macrod1) is an ADP-ribosylhydrolase 1 that is highly enriched in mitochondria, participating in the pathogenesis of cardiovascular diseases. In this study, we investigated the role of Macrod1 in DCM. A mice model was established by feeding a high-fat diet (HFD) and intraperitoneal injection of streptozotocin (STZ). We showed that Macrod1 expression levels were significantly downregulated in cardiac tissue of DCM mice. Reduced expression of Macrod1 was also observed in neonatal rat cardiomyocytes (NRCMs) treated with palmitic acid (PA, 400 μM) in vitro. Knockout of Macrod1 in DCM mice not only worsened glycemic control, but also aggravated cardiac remodeling, mitochondrial dysfunction, NAD+ consumption and oxidative stress, whereas cardiac-specific overexpression of Macrod1 partially reversed these pathological processes. In PA-treated NRCMs, overexpression of Macrod1 significantly inhibited PARP1 expression and restored NAD+ levels, activating SIRT3 to resist oxidative stress. Supplementation with the NAD+ precursor Niacin (50 μM) alleviated oxidative stress in PA-stimulated cardiomyocytes. We revealed that Macrod1 reduced NAD+ consumption by inhibiting PARP1 expression, thereby activating SIRT3 and anti-oxidative stress signaling. This study identifies Macrod1 as a novel target for DCM treatment. Targeting the PARP1-NAD+-SIRT3 axis may open a novel avenue to development of new intervention strategies in DCM. Schematic illustration of macrod1 ameliorating diabetic cardiomyopathy oxidative stress via PARP1-NAD+-SIRT3 axis.

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.

Cynarin alleviates acetaminophen-induced acute liver injury through the activation of Keap1/Nrf2-mediated lipid peroxidation defense via the AMPK/SIRT3 signaling pathway

Overdose of Acetaminophen (APAP) is a major contributor to acute liver injury (ALI), a complex pathological process with limited effective treatments. Emerging evidence links lipid peroxidation to APAP-induced ALI. Cynarin (Cyn), a hydroxycinnamic acid derivative, exhibits liver protective effects, but whether it mitigates APAP-induced ALI is unclear. Our aim was to verify the protective impact of Cyn on APAP-induced ALI and elucidate the molecular mechanisms governing this process. Herein, the regulation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) interaction was determined to be a novel mechanism underlying this protective impact of Cyn against APAP-induced ALI. Nrf2 deficiency increased the severity of APAP-induced ALI and lipid peroxidation and counteracted the protective effect of Cyn against this pathology. Additionally, Cyn promoted the dissociation of Nrf2 from Keap1, enhancing the nuclear translocation of Nrf2 and the transcription of downstream antioxidant proteins, thereby inhibiting lipid peroxidation. Molecular docking demonstrated that Cyn bound competitively to Keap1, and overexpression of Keap1 reversed Nrf2-activated anti-lipid peroxidation. Additionally, Cyn activated the adenosine monophosphate-activated protein kinase (AMPK)/sirtuin (SIRT)3 signaling pathway, which exhibits a protective effect on APAP-induced ALI. These findings propose that Cyn alleviates APAP-induced ALI by enhancing the Keap1/Nrf2-mediated lipid peroxidation defense via activation of the AMPK/SIRT3 signaling pathway.

Revitalizing Ancient Mitochondria with Nano-Strategies: Mitochondria-Remedying Nanodrugs Concentrate on Disease Control

Mitochondria, widely known as the energy factories of eukaryotic cells, have a myriad of vital functions across diverse cellular processes. Dysfunctions within mitochondria serve as catalysts for various diseases, prompting widespread cellular demise. Mounting research on remedying damaged mitochondria indicates that mitochondria constitute a valuable target for therapeutic intervention against diseases. But the less clinical practice and lower recovery rate imply the limitation of traditional drugs, which need a further breakthrough. Nanotechnology has approached favorable regiospecific biodistribution and high efficacy by capitalizing on excellent nanomaterials and targeting drug delivery. Mitochondria-remedying nanodrugs have achieved ideal therapeutic effects. This review elucidates the significance of mitochondria in various cells and organs, while also compiling mortality data for related diseases. Correspondingly, nanodrug-mediate therapeutic strategies and applicable mitochondria-remedying nanodrugs in disease are detailed, with a full understanding of the roles of mitochondria dysfunction and the advantages of nanodrugs. In addition, the future challenges and directions are widely discussed. In conclusion, this review provides comprehensive insights into the design and development of mitochondria-remedying nanodrugs, aiming to help scientists who desire to extend their research fields and engage in this interdisciplinary subject.

The potential of therapeutic strategies targeting mitochondrial biogenesis for the treatment of insulin resistance and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a persistent metabolic disorder marked by deficiencies in insulin secretion and/or function, affecting various tissues and organs and leading to numerous complications. Mitochondrial biogenesis, the process by which cells generate new mitochondria utilizing existing ones plays a crucial role in energy homeostasis, glucose metabolism, and lipid handling. Recent evidence suggests that promoting mitochondrial biogenesis can alleviate insulin resistance in the liver, adipose tissue, and skeletal muscle while improving pancreatic β-cell function. Moreover, enhanced mitochondrial biogenesis has been shown to ameliorate T2DM symptoms and may contribute to therapeutic effects for the treatment of diabetic nephropathy, cardiomyopathy, retinopathy, and neuropathy. This review summarizes the intricate connection between mitochondrial biogenesis and T2DM, highlighting the potential of novel therapeutic strategies targeting mitochondrial biogenesis for T2DM treatment and its associated complications. It also discusses several natural products that exhibit beneficial effects on T2DM by promoting mitochondrial biogenesis.

Heat Shock Protein 22 Attenuates Nerve Injury-induced Neuropathic Pain Via Improving Mitochondrial Biogenesis and Reducing Oxidative Stress Mediated By Spinal AMPK/PGC-1α Pathway in Male Rats

Heat shock protein 22 (hsp22) plays a significant role in mitochondrial biogenesis and redox balance. Moreover, it's well accepted that the impairment of mitochondrial biogenesis and redox imbalance contributes to the progress of neuropathic pain. However, there is no available evidence indicating that hsp22 can ameliorate mechanical allodynia and thermal hyperalgesia, sustain mitochondrial biogenesis and redox balance in rats with neuropathic pain. In this study, pain behavioral test, western blotting, immunofluorescence staining, quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and Dihydroethidium staining are applied to confirm the role of hsp22 in a male rat model of spared nerve injury (SNI). Our results indicate that hsp22 was significantly decreased in spinal neurons post SNI. Moreover, it was found that intrathecal injection (i.t.) with recombinant heat shock protein 22 protein (rhsp22) ameliorated mechanical allodynia and thermal hyperalgesia, facilitated nuclear respiratory factor 1 (NRF1)/ mitochondrial transcription factor A (TFAM)-dependent mitochondrial biogenesis, decreased the level of reactive oxygen species (ROS), and suppressed oxidative stress via activation of spinal adenosine 5'monophosphate-activated protein kinase (AMPK)/ peroxisome proliferative activated receptor γ coactivator 1α (PGC-1α) pathway in male rats with SNI. Furthermore, it was also demonstrated that AMPK antagonist (compound C, CC) or PGC-1α siRNA reversed the improved mechanical allodynia and thermal hyperalgesia, mitochondrial biogenesis, oxidative stress, and the decreased ROS induced by rhsp22 in male rats with SNI. These results revealed that hsp22 alleviated mechanical allodynia and thermal hyperalgesia, improved the impairment of NRF1/TFAM-dependent mitochondrial biogenesis, down-regulated the level of ROS, and mitigated oxidative stress through stimulating the spinal AMPK/PGC-1α pathway in male rats with SNI.

Recent advances in medicinal and edible homologous plant polysaccharides: Preparation, structure and prevention and treatment of diabetes

Medicinal and edible homologs (MEHs) can be used in medicine and food. The National Health Commission announced that a total of 103 kinds of medicinal and edible homologous plants (MEHPs) would be available by were available in 2023. Diabetes mellitus (DM) has become the third most common chronic metabolic disease that seriously threatens human health worldwide. Polysaccharides, the main component isolated from MEHPs, have significant antidiabetic effects with few side effects. Based on a literature search, this paper summarizes the preparation methods, structural characterization, and antidiabetic functions and mechanisms of MEHPs polysaccharides (MEHPPs). Specifically, MEHPPs mainly regulate PI3K/Akt, AMPK, cAMP/PKA, Nrf2/Keap1, NF-κB, MAPK and other signaling pathways to promote insulin secretion and release, improve glycolipid metabolism, inhibit the inflammatory response, decrease oxidative stress and regulate intestinal flora. Among them, 16 kinds of MEHPPs were found to have obvious anti-diabetic effects. This article reviews the prevention and treatment of diabetes and its complications by MEHPPs and provides a basis for the development of safe and effective MEHPP-derived health products and new drugs to prevent and treat diabetes.

Mulberry leaf flavonoids activate BAT and induce browning of WAT to improve type 2 diabetes via regulating the AMPK/SIRT1/PGC-1α signaling pathway

Mulberry (Morus alba L.) leaf is a well-established traditional Chinese botanical and culinary resource. It has found widespread application in the management of diabetes. The bioactive constituents of mulberry leaf, specifically mulberry leaf flavonoids (MLFs), exhibit pronounced potential in the amelioration of type 2 diabetes (T2D). This potential is attributed to their ability to safeguard pancreatic β cells, enhance insulin resistance, and inhibit α-glucosidase activity. Our antecedent research findings underscore the substantial therapeutic efficacy of MLFs in treating T2D. However, the precise mechanistic underpinnings of MLF's anti-T2D effects remain the subject of inquiry. Activation of brown/beige adipocytes is a novel and promising strategy for T2D treatment. In the present study, our primary objective was to elucidate the impact of MLFs on adipose tissue browning in db/db mice and 3T3-L1 cells and elucidate its underlying mechanism. The results manifested that MLFs reduced body weight and food intake, alleviated hepatic steatosis, improved insulin sensitivity, and increased lipolysis and thermogenesis in db/db mice. Moreover, MLFs activated brown adipose tissue (BAT) and induced the browning of inguinal white adipose tissue (IWAT) and 3T3-L1 adipocytes by increasing the expressions of brown adipocyte marker genes and proteins such as uncoupling protein 1 (UCP1) and beige adipocyte marker genes such as transmembrane protein 26 (Tmem26), thereby promoting mitochondrial biogenesis. Mechanistically, MLFs facilitated the activation of BAT and the induction of WAT browning to ameliorate T2D primarily through the activation of AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) signaling pathway. These findings highlight the unique capacity of MLF to counteract T2D by enhancing BAT activation and inducing browning of IWAT, thereby ameliorating glucose and lipid metabolism disorders. As such, MLFs emerge as a prospective and innovative browning agent for the treatment of T2D.

Phycocyanin as a nature-inspired antidiabetic agent: A systematic review

BACKGROUND

Nutraceuticals have been important for more than two decades for their safety, efficacy, and outstanding effects. Diabetes is a major metabolic syndrome, which may be improved using nutritional pharmaceuticals. Some microalgae species, such as spirulina, stand out by providing biomass with exceptional nutritional properties. Spirulina has a wide range of pharmacological effects, mostly related to phycocyanin. Phycocyanin is a protein compound with antidiabetic properties, known as a nutraceutical.

OBJECTIVE

This review delves into phycocyanin applications in diabetes and its complications and ascertains the mechanisms involved.

METHODS

Scopus, PubMed, Cochrane Library, Web of Science, and ProQuest databases were systematically reviewed (up to April 30, 2023), in which only animal and cellular studies were found.

RESULTS

According to animal studies, the administration of phycocyanin affected biochemical parameters (primary outcome) related to diabetes. These results showed an increase in fasting insulin serum and a decrease in fasting blood glucose, glycosylated serum protein, and glycosylated hemoglobin. In cellular studies, though, phycocyanin prevented methylglyoxal and human islet amyloid polypeptide-induced dysfunction in β-cells and induced apoptosis through different molecular pathways (secondary outcome), including activation of Nrf2, PI3K/Akt, and suppression of JNK and p38. Also, phycocyanin exerted its antidiabetic effect by affecting the pathways regulating hepatic glucose metabolism.

CONCLUSIONS

Thus, based on the available information and literature, targeting these pathways by phycocyanin may unleash an array of benefits, including positive outcomes of the antidiabetic effects of phycocyanin as a nutraceutical.

OTHER

This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) at the National Institute of Health. The registration number is CRD42022307522.

Effects of Redox Homeostasis and Mitochondrial Damage on Alzheimer's Disease

Bioenergetic mitochondrial dysfunction is a common feature of several diseases, including Alzheimer's disease (AD), where redox imbalance also plays an important role in terms of disease development. AD is an age-related disease and begins many years before the appearance of neurodegenerative symptoms. Intracellular tau aggregation, extracellular β-amyloid (Aβ) deposition in the brain, and even the APOE4 genotype contribute to the process of AD by impairing redox homeostasis and mitochondrial dysfunction. This review summarizes the evidence for the redox imbalance and mitochondrial dysfunction in AD and demonstrates the current therapeutic strategies related to mitochondrial maintenance.

Activation of PGC-1α-dependent mitochondrial biogenesis supports therapeutic effects of silibinin against type I diabetic periodontitis

AIM

To investigate whether silibinin impacts diabetic periodontitis (DP) via mitochondrial regulation.

MATERIALS AND METHODS

In vivo, rats were divided into control, diabetes, DP and DP combined with silibinin groups. Diabetes and periodontitis were induced by streptozocin and silk ligation, respectively. Bone turnover was evaluated by microcomputed tomography, histology and immunohistochemistry. In vitro, human periodontal ligament cells (hPDLCs) were exposed to hydrogen peroxide (H2 O2 ) with or without silibinin. Osteogenic function was analysed by Alizarin Red and alkaline phosphatase staining. Mitochondrial function and biogenesis were investigated by mitochondrial imaging assays and quantitative polymerase chain reaction. Activator and lentivirus-mediated knockdown of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha (PGC-1α), a critical regulator of mitochondria biogenesis, was used to explore the mitochondrial mechanisms.

RESULTS

Silibinin attenuated periodontal destruction and mitochondrial dysfunction and enhanced mitochondrial biogenesis and PGC-1α expression in rats with DP. Meanwhile, silibinin promoted cell proliferation, osteogenesis and mitochondrial biogenesis and increased the PGC-1α level in hPDLCs exposed to H2 O2 . Silibinin also protected PGC-1α from proteolysis in hPDLCs. Furthermore, both silibinin and activator of PGC-1α ameliorated cellular injury and mitochondrial abnormalities in hPDLCs, while knockdown of PGC-1α abolished the beneficial effect of silibinin.

CONCLUSIONS

Silibinin attenuated DP through the promotion of PGC-1α-dependent mitochondrial biogenesis.

SS-31 alleviated nociceptive responses and restored mitochondrial function in a headache mouse model via Sirt3/Pgc-1α positive feedback loop

Migraine is the second highest cause of disability worldwide, bringing a huge socioeconomic burden. Improving mitochondrial function has promise as an effective treatment strategy for migraine. Szeto-Schiller peptide (SS-31) is a new mitochondria-targeted tetrapeptide molecule that has been shown to suppress the progression of diseases by restoring mitochondrial function, including renal disease, cardiac disease, and neurodegenerative disease. However, whether SS-31 has a therapeutic effect on migraine remains unclear. The aim of this study is to clarify the treatment of SS-31 for headache and its potential mechanisms. Here we used a mouse model induced by repeated dural infusion of inflammatory soup (IS), and examined roles of Sirt3/Pgc-1α positive feedback loop in headache pathogenesis and mitochondrial function. Our results showed that repeated IS infusion impaired mitochondrial function, mitochondrial ultrastructure and mitochondrial homeostasis in the trigeminal nucleus caudalis (TNC). These IS-induced damages in TNC were reversed by SS-31. In addition, IS-induced nociceptive responses were simultaneously alleviated. The effects of SS-31 on mitochondrial function and mitochondrial homeostasis (mainly mitochondrial biogenesis) were attenuated partially by the inhibitor of Sirt3/Pgc-1α. Overexpression of Sirt3/Pgc-1α increased the protein level of each other. These results indicated that SS-31 alleviated nociceptive responses and restored mitochondrial function in an IS-induced headache mouse model via Sirt3/Pgc-1α positive feedback loop. SS-31 has the potential to be an effective drug candidate for headache treatment.

Biodegradable Hollow Nanoscavengers Restore Liver Functions to Reverse Insulin Resistance in Type 2 Diabetes

Type 2 diabetes (T2D) results from the cells' insulin resistance, and to date, insulin therapy and diabetes medications targeting glycemic management have failed to reverse the increase in T2D prevalence. Restoring liver functions to improve hepatic insulin resistance by reducing oxidative stress is a potential strategy for T2D treatment. Herein, the liver-targeted biodegradable silica nanoshells embedded with platinum nanoparticles (Pt-SiO₂) are designed as reactive oxygen species (ROS) nanoscavengers and functional hollow nanocarriers. Then, 2,4-dinitrophenol-methyl ether (DNPME, mitochondrial uncoupler) is loaded inside Pt-SiO₂, followed by coating a lipid bilayer (D@Pt-SiO₂@L) for long-term effective ROS removal (platinum nanoparticles scavenge overproduced ROS, while DNPME inhibits ROS production) in the liver tissue of T2D models. It is found that D@Pt-SiO₂@L reverses elevated oxidative stress, insulin resistance, and impaired glucose consumption in vitro, and significantly improves hepatic steatosis and antioxidant capacity in diabetic mice models induced by a high-fat diet and streptozotocin. Moreover, intravenous administration of D@Pt-SiO₂@L indicates therapeutic effects on hyperlipidemia, insulin resistance, hyperglycemia, and diabetic nephropathy, which provides a promising approach for T2D treatment by reversing hepatic insulin resistance through long-term ROS scavenging.

BaoShenTongLuo formula protects against podocyte injury by regulating AMPK-mediated mitochondrial biogenesis in diabetic kidney disease

BACKGROUND

Mitochondrial dysfunction is considered to be an important contributor in podocyte injury under diabetic conditions. The BaoShenTongLuo (BSTL) formula has been shown to reduce podocyte damage and postpone the progression of diabetic kidney disease (DKD). The potential mechanisms underlying the effects of BSTL, however, have yet to be elucidated. In this study, we aimed to investigate whether the effects of BSTL are related to the regulation of mitochondrial biogenesis via the adenosine monophosphate-activated protein kinase (AMPK) pathway.

METHODS

High-Performance Liquid Chromatography Electrospray Ionization Mass Spectrometer (HPLC-ESI-MS) analysis was performed to investigate the characteristics of pure compounds in BSTL. db/db mice and mouse podocyte clone-5 (MPC5) cells were exposed to high glucose (HG) to induce DKD and podocyte damage. Body weight, random blood glucose, urinary albumin/creatinine ratio (UACR), indicators of renal function and renal histological lesions were measured. Markers of podocyte injury, mitochondrial morphology, mitochondrial deoxyribonucleic acid (mtDNA) content, mitochondrial respiratory chain complexes activities, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP) levels were assessed. Protein expressions of AMPK, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), transcription factor A (TFAM), mitochondrial fusion protein 2 (MFN2) and dynamin-related protein 1 (DRP1) were also detected. MPC5 cells were transfected with AMPKα small interfering RNA (AMPKα siRNA) to determine the underlying mechanisms of BSTL improvement of mitochondrial function under diabetic conditions.

RESULTS

In vivo, treatment with BSTL reduced the UACR levels, reversed the histopathological changes in renal tissues, and alleviated the podocyte injury observed in db/db mice. After BSTL treatment, the decreased mtDNA content and mitochondrial respiratory chain complex I, III, and IV activities were significantly improved, and these effects were accompanied by maintenance of the protein expression of p-AMPKαT172, PGC-1α, TFAM and MFN2. The in vitro experiments also showed that BSTL reduced podocyte apoptosis, suppressed excessive cellular ROS production, and reversed the decreased in MMP that were observed under HG conditions. More importantly, the effects of BSTL in enhancing mitochondrial biogenesis and reducing podocyte apoptosis were inhibited in AMPKα siRNA-treated podocytes.

CONCLUSION

BSTL plays a crucial role in protecting against podocyte injury by regulating the AMPK-mediated mitochondrial biogenesis in DKD.

Remote ischemic preconditioning protects against spinal cord ischemia-reperfusion injury in mice by activating NMDAR/AMPK/PGC-1α/SIRT3 signaling

BACKGROUND

To study the protective effects of delayed remote ischemic preconditioning (RIPC) against spinal cord ischemia-reperfusion injury (SCIRI) in mice and determine whether SIRT3 is involved in this protection and portrayed its upstream regulatory mechanisms.

METHODS

In vivo, WT or SIRT3 global knockout (KO) mice were exposed to right upper and lower limbs RIPC or sham ischemia. After 24 h, the abdominal aorta was clamped for 20 min, then re-perfused for 3 days. The motor function of mice, number of Nissl bodies, apoptotic rate of neurons, and related indexes of oxidative stress in the spinal cord were measured to evaluate for neuroprotective effects. The expression and correlation of SIRT3 and NMDAR were detected by WB and immunofluorescence. In vitro, primary neurons were exacted and OGD/R was performed to simulate SCIRI in vivo. Neuronal damage was assessed by observing neuron morphology, detecting LDH release ratio, and flow cytometry to analyze the apoptosis. MnSOD and CAT enzyme activities, GSH and ROS level were also measured to assess neuronal antioxidant capacity. NMDAR-AMPK-PGC-1α signaling was detected by WB to portray upstream regulatory mechanisms of RIPC regulating SIRT3.

RESULTS

Compared to the SCIRI mice without RIPC, mice with RIPC displayed improved motor function recovery, a reduced neuronal loss, and enhanced antioxidant capacity. To the contrary, the KO mice did not exhibit any effect of RIPC-induced neuroprotection. Similar results were observed in vitro. Further analyses with spinal cord tissues or primary neurons detected enhanced MnSOD and CAT activities, as well as increased GSH level but decreased MDA or ROS production in the RIPC + I/R mice or NMDA + OGD/R neurons. However, these changes were completely inhibited by the absence of SIRT3. Additionally, NMDAR-AMPK-PGC-1α signaling was activated to upregulate SIRT3 levels, which is essential for RIPC-mediated neuroprotection.

CONCLUSIONS

RIPC enhances spinal cord ischemia tolerance in a SIRT3-dependent manner, and its induced elevated SIRT3 levels are mediated by the NMDAR-AMPK-PGC-1α signaling pathway. Combined therapy targeting SIRT3 is a promising direction for treating SCIRI.

A unique insight for Xiaoyao San exerts antidepressant effects by modulating hippocampal glucose catabolism using stable isotope-resolved metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine (TCM) theory, depression is an emotional disease, which is thought to be related to stagnation of liver qi and dysfunction of the spleen in transport. Xiaoyao San (XYS) is considered to have the effects of soothing liver-qi stagnation and invigorating the spleen. The spleen has the function to transport and transform nutrients. The liver has also termed the center of energy metabolism in the body. Therefore, exploring the antidepressant effects of XYS from the perspective of energy metabolism may reveal new findings.

AIM OF THE STUDY

Glucose catabolism is an important part of energy metabolism. In recent years, several researchers have found that XYS can exert antidepressant effects by modulating abnormalities in glucose catabolism-related metabolites. The previous research of our research group found that the hippocampus glucose catabolism was disordered in depression. However, the antidepressant potential of XYS through modulating the disorders of hippocampal glucose catabolism and the specific metabolic pathways and targets of XYS action were still unknown. The aim of this study was to address the above scientific questions.

MATERIALS AND METHODS

In this research, the CUMS (chronic unpredictable mild stress) model was used as the animal model of depression. The antidepressant effect of XYS was evaluated by behavioral indicators. The specific pathways and targets of XYS modulating the disorders of glucose catabolism in the hippocampus of CUMS rats were obtained by stable isotope-resolved metabolomics. Further, the isotope tracing results were also verified by molecular biology and electron transmission electron microscopy.

RESULTS

The results demonstrated that XYS pretreatment could significantly improve the depressive symptoms induced by CUMS. More importantly, it was found that XYS could modulate the disorders of glucose catabolism in the hippocampus of CUMS rats. Stable isotope-resolved metabolomics and enzyme activity tests showed that Lactate dehydrogenase (LDH), Pyruvate carboxylase (PC), and Pyruvate dehydrogenase (PDH) were targets of XYS for modulating the disorders of glucose catabolism in the hippocampus of CUMS rats. The Succinate dehydrogenase (SDH) and mitochondrial respiratory chain complex V (MRCC-Ⅴ) were targets of XYS to improve abnormal mitochondrial oxidative phosphorylation in the hippocampus of CUMS rats. XYS was also found to have the ability to improve the structural damage of mitochondria and nuclei in the hippocampal caused by CUMS.

CONCLUSIONS

This study was to explore the antidepressant effect of XYS from the perspective of glucose catabolism based on a strategy combining stable isotope tracing, molecular biology techniques, and transmission electron microscopy. We not only obtained the specific pathways and targets of XYS to improve the disorders of glucose catabolism in the hippocampus of CUMS rats, but also revealed the specific targets of the pathways of XYS compared with VLF.

FFAR4 improves the senescence of tubular epithelial cells by AMPK/SirT3 signaling in acute kidney injury

Acute kidney injury (AKI) is a serious clinical complication with high morbidity and mortality rates. Despite substantial progress in understanding the mechanism of AKI, no effective therapy is available for treatment or prevention. We previously found that G protein-coupled receptor (GPCR) family member free fatty acid receptor 4 (FFAR4) agonist TUG891 alleviated kidney dysfunction and tubular injury in AKI mice. However, the versatile role of FFAR4 in kidney has not been well characterized. In the study, the expression of FFAR4 was abnormally decreased in tubular epithelial cells (TECs) of cisplatin, cecal ligation/perforation and ischemia/reperfusion injury-induced AKI mice, respectively. Systemic and conditional TEC-specific knockout of FFAR4 aggravated renal function and pathological damage, whereas FFAR4 activation by TUG-891 alleviated the severity of disease in cisplatin-induced AKI mice. Notably, FFAR4, as a key determinant, was firstly explored to regulate cellular senescence both in injured kidneys of AKI mice and TECs, which was indicated by senescence-associated β-galactosidase (SA-β-gal) activity, marker protein p53, p21, Lamin B1, phospho-histone H2A.X, phospho-Rb expression, and secretory phenotype IL-6 level. Mechanistically, pharmacological activation and overexpression of FFAR4 reversed the decrease of aging-related SirT3 protein, where FFAR4 regulated SirT3 expression to exhibit anti-senescent effect via Gq subunit-mediated CaMKKβ/AMPK signaling in cisplatin-induced mice and TECs. These findings highlight the original role of tubular FFAR4 in cellular senescence via AMPK/SirT3 signaling and identify FFAR4 as a potential drug target against AKI.

Emerging roles of Sirtuins in alleviating alcoholic liver Disease: A comprehensive review

Sirtuins (SIRTs), a NAD⁺ family of dependent deacetylases, are involved in the regulation of various human diseases. Recently, accumulating evidence has uncovered number of substrates and crucial roles of SIRTs in the pathogenesis of alcoholic liver disease (ALD). However, systematic reports are still lacking, so this review provides a comprehensive profile of the crucial physiological functions of SIRTs and its role in attenuating ALD, including alcoholic liver steatosis, steatohepatitis, and fibrosis. SIRTs play beneficial roles in energy/lipid metabolism, oxidative stress, inflammatory response, mitochondrial homeostasis, autophagy and necroptosis of ALD via regulating multiple signaling transduction pathways such as AMPK, LKB1, SREBP1, Lipin1, PGC-1α, PPARα/γ, FoxO1/3a, Nrf2/p62, mTOR, TFEB, RIPK1/3, HMGB1, NFATc4, NF-κB, TLR4, NLRP3, P2X7R, MAPK, TGF1β/Smads and Wnt/β-catenin. In addition, the mechanism and clinical application of natural/ synthetic SIRTs agonists in ALD are summarized, which provide a new idea for the treatment of ALD and basic foundation for further studies into target drugs.

Curcumin alleviates hepatic steatosis by improving mitochondrial function in postnatal overfed rats and fatty L02 cells through the SIRT3 pathway

Postnatal overfeeding could increase the risk of non-alcoholic fatty liver disease (NAFLD) in adulthood. This study investigated the effects of curcumin (CUR) on hepatic steatosis in postnatal overfed rats and elucidated potential mechanisms in mitochondrial functions. Male rats were adjusted to ten (normal litter, NL) or three (small litter, SL) at postnatal day 3. After weaning, NL rats were fed with normal diet (NL) or a high-fat diet (NH) for 10 weeks. SL rats were fed with normal diet (SL), a high-fat diet (SH), a normal diet supplemented with 2% CUR (SL-CUR) or a high-fat diet supplemented with 2% CUR (SH-CUR). At week 13, compared with NL rats, SL and NH rats showed increased body weight, glucose intolerance, dyslipidemia and hepatic lipid accumulation, and these changes were more obvious in SH rats. The opposite trends were observed in SL-CUR and SH-CUR rats. Moreover, CUR could preserve mitochondrial biogenesis and antioxidant response in postnatal overfed rats, and upregulated the mRNA and protein levels of SIRT3. In vitro, L02 cells were exposed to free fatty acids and/or CUR. CUR decreased the levels of cellular lipids and mitochondrial reactive oxygen species, and increased the mitochondrial DNA copy number and superoxide dismutase activity in fatty L02 cells. However, these effects were blocked after SIRT3 silencing. It was concluded that postnatal overfeeding damaged mitochondrial biogenesis and antioxidant response, and increased hepatic lipids and the severity of high-fat-induced NAFLD, while CUR alleviated hepatic steatosis, at least partially, by enhancing mitochondrial function through SIRT3.

AMPK signaling in diabetes mellitus, insulin resistance and diabetic complications: A pre-clinical and clinical investigation

Diabetes mellitus (DM) is considered as a main challenge in both developing and developed countries, as lifestyle has changed and its management seems to be vital. Type I and type II diabetes are the main kinds and they result in hyperglycemia in patients and related complications. The gene expression alteration can lead to development of DM and related complications. The AMP-activated protein kinase (AMPK) is an energy sensor with aberrant expression in various diseases including cancer, cardiovascular diseases and DM. The present review focuses on understanding AMPK role in DM. Inducing AMPK signaling promotes glucose in DM that is of importance for ameliorating hyperglycemia. Further investigation reveals the role of AMPK signaling in enhancing insulin sensitivity for treatment of diabetic patients. Furthermore, AMPK upregulation inhibits stress and cell death in β cells that is of importance for preventing type I diabetes development. The clinical studies on diabetic patients have shown the role of AMPK signaling in improving diabetic complications such as brain disorders. Furthermore, AMPK can improve neuropathy, nephropathy, liver diseases and reproductive alterations occurring during DM. For exerting such protective impacts, AMPK signaling interacts with other molecular pathways such as PGC-1α, PI3K/Akt, NOX4 and NF-κB among others. Therefore, providing therapeutics based on AMPK targeting can be beneficial for amelioration of DM.

XJB-5-131 Is a Mild Uncoupler of Oxidative Phosphorylation

BACKGROUND

Mitochondria (MT) are energy "powerhouses" of the cell and the decline in their function from oxidative damage is strongly correlated in many diseases. To suppress oxygen damage, we have developed and applied XJB-5-131 as a targeted platform for neutralizing reactive oxygen species (ROS) directly in MT. Although the beneficial activity of XJB-5-131 is well documented, the mechanism of its protective effects is not yet fully understood.

OBJECTIVE

Here, we elucidate the mechanism of protection for XJB-5-131, a mitochondrial targeted antioxidant and electron scavenger.

METHODS

The Seahorse Flux Analyzer was used to probe the respiratory states of isolated mouse brain mitochondria treated with XJB-5-131 compared to controls.

RESULTS

Surprisingly, there is no direct impact of XJB-5-131 radical scavenger on the electron flow through the electron transport chain. Rather, XJB-5-131 is a mild uncoupler of oxidative phosphorylation. The nitroxide moiety in XJB-5-131 acts as a superoxide dismutase mimic, which both extracts or donates electrons during redox reactions. The electron scavenging activity of XJB-5-131 prevents the leakage of electrons and reduces formation of superoxide anion, thereby reducing ROS.

CONCLUSION

We show here that XJB-5-131 is a mild uncoupler of oxidative phosphorylation in MT. The mild uncoupling property of XJB-5-131 arises from its redox properties, which exert a protective effect by reducing ROS-induced damage without sacrificing energy production. Because mitochondrial decline is a common and central feature of toxicity, the favorable properties of XJB-5-131 are likely to be useful in treating Huntington's disease and a wide spectrum of neurodegenerative diseases for which oxidative damage is a key component. The mild uncoupling properties of XJB-5-131 suggest a valuable mechanism of action for the design of clinically effective antioxidants.

Mitochondrial Sirtuins in Reproduction

Mitochondria act as hubs of numerous metabolic pathways. Mitochondrial dysfunctions contribute to altering the redox balance and predispose to aging and metabolic alterations. The sirtuin family is composed of seven members and three of them, SIRT3-5, are housed in mitochondria. They catalyze NAD+-dependent deacylation and the ADP-ribosylation of mitochondrial proteins, thereby modulating gene expression and activities of enzymes involved in oxidative metabolism and stress responses. In this context, mitochondrial sirtuins (mtSIRTs) act in synergistic or antagonistic manners to protect from aging and aging-related metabolic abnormalities. In this review, we focus on the role of mtSIRTs in the biological competence of reproductive cells, organs, and embryos. Most studies are focused on SIRT3 in female reproduction, providing evidence that SIRT3 improves the competence of oocytes in humans and animal models. Moreover, SIRT3 protects oocytes, early embryos, and ovaries against stress conditions. The relationship between derangement of SIRT3 signaling and the imbalance of ROS and antioxidant defenses in testes has also been demonstrated. Very little is known about SIRT4 and SIRT5 functions in the reproductive system. The final goal of this work is to understand whether sirtuin-based signaling may be taken into account as potential targets for therapeutic applications in female and male infertility.