Berberine protects against high fat diet-induced dysfunction in muscle mitochondria by inducing SIRT1-dependent mitochondrial biogenesis

Mitochondrial Adaptation in Skeletal Muscle: Impact of Obesity, Caloric Restriction, and Dietary Compounds

PURPOSE OF REVIEW: The global obesity epidemic has become a major public health concern, necessitating comprehensive research into its adverse effects on various tissues within the human body. Among these tissues, skeletal muscle has gained attention due to its susceptibility to obesity-related alterations. Mitochondria are primary source of energy production in the skeletal muscle. Healthy skeletal muscle maintains constant mitochondrial content through continuous cycle of synthesis and degradation. However, obesity has been shown to disrupt this intricate balance. This review summarizes recent findings on the impact of obesity on skeletal muscle mitochondria structure and function. In addition, we summarize the molecular mechanism of mitochondrial quality control systems and how obesity impacts these systems. RECENT FINDINGS: Recent findings show various interventions aimed at mitigating mitochondrial dysfunction in obese model, encompassing strategies including caloric restriction and various dietary compounds. Obesity has deleterious effect on skeletal muscle mitochondria by disrupting mitochondrial biogenesis and dynamics. Caloric restriction, omega-3 fatty acids, resveratrol, and other dietary compounds enhance mitochondrial function and present promising therapeutic opportunities.

Berberine Attenuates Acetamiprid Exposure-Induced Mitochondrial Dysfunction and Apoptosis in Rats via Regulating the Antioxidant Defense System

Acetamiprid (ACMP) is a neonicotinoid insecticide that poses a significant threat to the environment and mankind. Oxidative stress and mitochondrial dysfunction are considered prime contributors to ACMP-induced toxic effects. Meanwhile, berberine (BBR) a natural plant alkaloid, is a topic of interest because of its therapeutic and prophylactic actions. Therefore, this study evaluated the effects of BBR on ACMP-mediated alterations in mitochondrial functions and apoptosis in rat liver tissue. Male Wistar rats were divided into four groups: (I) control, (II) BBR-treated, (III) ACMP-exposed, and (IV) BBR+ACMP co-treated groups. The doses of BBR (150 mg/kg b.wt) and ACMP (1/10 of LD50, i.e., 21.7 mg/kg b.wt) were given intragastrically for 21 consecutive days. The results showed that the administration of ACMP diminished mitochondrial complex activity, downregulated complex I (ND1 and ND2) and complex IV (COX1 and COX4) subunit mRNA expression, depleted the antioxidant defense system, and induced apoptosis in rat liver. BBR pre-treatment significantly attenuated ACMP-induced mitochondrial dysfunction by maintaining mitochondrial complex activity and upregulating ND1, ND2, COX1, and COX4 mRNA expression. BBR reversed ACMP-mediated apoptosis by diminishing Bax and caspase-3 and increasing the Bcl-2 protein level. BBR also improved the mitochondrial antioxidant defense system by upregulating mRNA expression of PGC-1α, MnSOD, and UCP-2 in rat liver tissue. This study is the first to evaluate the protective potential of BBR against pesticide-induced mitochondrial dysfunction in liver tissue. In conclusion, BBR offers protection against ACMP-induced impairment in mitochondrial functions by maintaining the antioxidant level and modulating the apoptotic cascade.

Berberine prevents against myocardial injury induced by acute β-adrenergic overactivation in rats

The overactivation of β-adrenergic receptors (β-ARs) can result in acute myocardial ischemic injury, culminating in myocardial necrosis. Berberine (BBR) has exhibited promising potential for prevention and treatment in various heart diseases. However, its specific role in mitigating myocardial injury induced by acute β-AR overactivation remains unexplored. This study aimed to investigate the effects and underlying mechanisms of BBR pretreatment in a rat model of acute β-AR overactivation induced by a single dose of the nonselective β-adrenergic agonist isoprenaline (ISO). Rats were pretreated with saline or BBR (100 mg/kg/day) via gavage for 14 consecutive days, followed by a subcutaneous injection of ISO or saline on the 14th day. The findings indicated that BBR pretreatment significantly attenuated myocardial injury in ISO-stimulated rats, as evidenced by reduced pathological inflammatory infiltration, necrosis, and serum markers of myocardial damage. Additionally, BBR decreased oxidative stress and inflammation in the system and heart. Furthermore, BBR pretreatment enhanced myocardial ATP levels, improved mitochondrial dysfunction through increased Drp1 phosphorylation, and augmented myocardial autophagy. In a CoCl2-induced H9c2 cell hypoxic injury model, BBR pretreatment mitigated cellular injury, apoptosis, and oxidative stress while upregulating Drp1 and autophagy-associated proteins. Mechanistically, BBR pretreatment activated AKT, AMPK, and LKB1 both in vivo and in vitro, implicating the involvement of the AKT and LKB1/AMPK signaling pathways in its cardioprotective effects. Our study demonstrated the protective effects of BBR against myocardial injury induced by acute β-AR overactivation in rats, highlighting the potential of BBR as a preventive agent for myocardial injury associated with β-adrenergic overactivation.

Resveratrol attenuates against high-fat-diet-promoted non-alcoholic fatty liver disease in rats mainly by targeting the miR-34a/SIRT1 axis

This study evaluated if miR-34a/SIRT1 signalling mediates the anti-hepatosteatotic effect of resveratrol (RSV) in high-fat-diet (HFD)-fed rats. Rats were divided into seven groups (n = 6/each) as control, control + miR-34a agomir negative control, HFD, HFD + miR-34a, HFD + RSV, HFD + RSV + Ex-527 (a SIRT1 inhibitor), and HFD + RSV + miR-34a agomir. After 8 weeks, RSV suppressed dyslipidemia, lowered fasting glucose and insulin levels, improved insulin sensitivity, and prevented hepatic lipid accumulation. These effects were associated with hepatic downregulation of SREBP1 and SREBP2, upregulation of PPARα, and acetylation of Nrf2 (activation) and NF-κβ p65 (inhibition). Also, RSV reduced the transcription of miR-34a and increased the nuclear localisation of SIRT1 in the livers, muscles, and adipose tissues of HFD-fed rats. All these effects were prevented by EX-527 and miR-34a agmir. In conclusion, RSV prevents HFD-induced insulin resistance and hepatic steatosis by suppressing miR-34a-induced activation of SIRT1.

The clinical efficacy and safety of berberine in the treatment of non-alcoholic fatty liver disease: a meta-analysis and systematic review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is becoming increasingly prevalent worldwide, emerging as a significant health issue on a global scale. Berberine exhibits potential for treating NAFLD, but clinical evidence remains inconclusive. This meta-analysis was conducted to assess the efficacy and safety of berberine for treating NAFLD.

METHODS

This study was registered with PROSPERO (No. CRD42023462338). Identification of randomized controlled trials (RCTs) involved searching 6 databases covering the period from their initiation to 9 September 2023. The primary outcomes comprised liver function markers such as glutamyl transpeptidase (GGT), alanine transaminase (ALT), aspartate transaminase (AST), lipid indices including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), homeostasis model assessment for insulin resistance (HOMA-IR) and body mass index (BMI). Review Manager 5.4 and STATA 17.0 were applied for analysis.

RESULTS

Among 10 RCTs involving 811 patients, berberine demonstrated significant reductions in various parameters: ALT (standardized mean difference (SMD) = - 0.72), 95% confidence interval (Cl) [- 1.01, - 0.44], P < 0.00001), AST (SMD = - 0.79, 95% CI [- 1.17, - 0.40], P < 0.0001), GGT (SMD = - 0.62, 95% CI [- 0.95, - 0.29], P = 0.0002), TG (SMD = - 0.59, 95% CI [- 0.86, - 0.31], P < 0.0001), TC(SMD = - 0.74, 95% CI [- 1.00, - 0.49], P < 0.00001), LDL-C (SMD = - 0.53, 95% CI [- 0.88, - 0.18], P = 0.003), HDL-C (SMD = - 0.51, 95% CI [- 0.12, 1.15], P = 0.11), HOMA-IR (SMD = - 1.56, 95% CI [- 2.54, - 0.58], P = 0.002), and BMI (SMD = - 0.58, 95% CI [- 0.77, - 0.38], P < 0.00001). Importantly, Berberine exhibited a favorable safety profile, with only mild gastrointestinal adverse events reported.

CONCLUSION

This meta-analysis demonstrates berberine's efficacy in improving liver enzymes, lipid profile, and insulin sensitivity in NAFLD patients. These results indicate that berberine shows promise as an adjunct therapy for NAFLD. Trial registration The protocol was registered with PROSPERO (No. CRD42023462338). Registered on September 27, 2023.

SIRT1 activation attenuates palmitate induced apoptosis in C2C12 muscle cells

BACKGROUND

Type 2 diabetes is characterized by insulin resistance, which manifests mainly in skeletal muscles. SIRT1 has been found to play a role in the insulin signaling pathway. However, the molecular underpinnings of SIRT1's function in palmitate fatty acid-induced apoptosis still need to be better understood.

METHODS

In this research, skeletal muscle cells are treated with palmitate to be insulin resistant. It is approached that SIRT1 is downregulated in C2C12 muscle cells during palmitate-induced apoptosis and that activating SIRT1 mitigates this effect.

RESULTS

Based on these findings, palmitate-induced apoptosis suppressed mitochondrial biogenesis by lowering PGC-1 expression, while SIRT1 overexpression boosted. The SIRT1 inhibitor sirtinol, on the other hand, decreased mitochondrial biogenesis under the same conditions. This research also shows that ROS levels rise in the conditions necessary for apoptosis induction by palmitate, and ROS inhibitors can mitigate this effect. This work demonstrated that lowering ROS levels by boosting SIRT1 expression inhibited apoptotic induction in skeletal muscle cells.

CONCLUSION

This study's findings suggested that SIRT1 can improve insulin resistance in type 2 diabetes by slowing the rate of lipo-apoptosis and boosting mitochondrial biogenesis, among other benefits.

Berberine prevents NAFLD and HCC by modulating metabolic disorders

Non-alcoholic fatty liver disease (NAFLD) is a global metabolic disease with high prevalence in both adults and children. Importantly, NAFLD is becoming the main cause of hepatocellular carcinoma (HCC). Berberine (BBR), a naturally occurring plant component, has been demonstrated to have advantageous effects on a number of metabolic pathways as well as the ability to kill liver tumor cells by causing cell death and other routes. This permits us to speculate and make assumptions about the value of BBR in the prevention and defense against NAFLD and HCC by a global modulation of metabolic disorders. Herein, we briefly describe the etiology of NAFLD and NAFLD-related HCC, with a particular emphasis on analyzing the potential mechanisms of BBR in the treatment of NAFLD from aspects including increasing insulin sensitivity, controlling the intestinal milieu, and controlling lipid metabolism. We also elucidate the mechanism of BBR in the treatment of HCC. More significantly, we provided a list of clinical studies for BBR in NAFLD. Taking into account our conclusions and perspectives, we can make further progress in the treatment of BBR in NAFLD and NAFLD-related HCC.

The significance of caloric restriction mimetics as anti-aging drugs

Aging is an intricate process characterized by the gradual deterioration of the physiological integrity of a living organism. This unfortunate phenomenon inevitably leads to a decline in functionality and a heightened susceptibility to the ultimate fate of mortality. Therefore, it is of utmost importance to implement interventions that possess the capability to reverse or preempt age-related pathology. Caloric restriction mimetics (CRMs) refer to a class of molecules that have been observed to elicit advantageous outcomes on both health and longevity in various model organisms and human subjects. Notably, these compounds offer a promising alternative to the arduous task of adhering to a caloric restriction diet and mitigate the progression of the aging process and extend the duration of life in laboratory animals and human population. A plethora of molecular signals have been linked to the practice of caloric restriction, encompassing Insulin-like Growth Factor 1 (IGF1), Mammalian Target of Rapamycin (mTOR), the Adenosine Monophosphate-Activated Protein Kinase (AMPK) pathway, and Sirtuins, with particular emphasis on SIRT1. Therefore, this review will center its focus on several compounds that act as CRMs, highlighting their molecular targets, chemical structures, and mechanisms of action. Moreover, this review serves to underscore the significant relationship between post COVID-19 syndrome, antiaging, and importance of utilizing CRMs. This particular endeavor will serve as a comprehensive guide for medicinal chemists and other esteemed researchers, enabling them to meticulously conceive and cultivate novel molecular entities with the potential to function as efficacious antiaging pharmaceutical agents.

Berberine-induced glucagon-like peptide-1 and its mechanism for controlling type 2 diabetes mellitus: a comprehensive pathway review

Introduction: A growing number of studies have thus far showed the association between type 2 diabetes mellitus (DM) and the intestinal microbiome homoeostasis. As reported, the gut microflora can be significantly different in patients with type 2 DM (T2DM) compared to those in healthy individuals.Methods: The authors collected the relevant articles published until 2022 and these are carefully selected from three scientific databases based on keywords.Discussion: This review highlights research on the anti-diabetic properties of berberine (BBR)-induced glucagon-like peptide-1 (GLP-1), as a glucose-lowering factor and a balance regulator in the microbial flora of the intestines, which plays an important role in adjusting the signalling pathways affecting insulin secretion.Results: Considering the anti-diabetic characteristics of the BBR-induced GLP-1, BBR makes a promising complementary treatment for reducing the clinical symptoms of DM by reducing the hyperglycaemia. Berberin might be a safe and effective drug for T2DM with little or no adverse effects.HighlightsBerberine induces GLP-1 insulin secretion by PLC2 pathway in the intestinalBerberine-induced GLP-1 decreases mitochondrial stress and relocates cytochrome c out of the mitochondria.Berberine induces GLP-1 secretion in the intestine by altering the bacterial profile, thus could possibly lighten diabetes symptomsBerberine-induced SCFA production, SCFA causes GLP-1 secretion from the intestinal L-Cell.Preventing mitochondrial damage, reducing adipose tissue fat, and reducing oxidative stress are thus among the results of BBR-induced GLP-1.The lower costs of BBR, and its limited side effects and higher availability, make it a promising supplementary medicine for DM.

Preservation of Mitochondrial Health in Liver Ischemia/Reperfusion Injury

Liver ischemia-reperfusion injury (LIRI) is a major cause of the development of complications in different clinical settings such as liver resection and liver transplantation. Damage arising from LIRI is a major risk factor for early graft rejection and is associated with higher morbidity and mortality after surgery. Although the mechanisms leading to the injury of parenchymal and non-parenchymal liver cells are not yet fully understood, mitochondrial dysfunction is recognized as a hallmark of LIRI that exacerbates cellular injury. Mitochondria play a major role in glucose metabolism, energy production, reactive oxygen species (ROS) signaling, calcium homeostasis and cell death. The diverse roles of mitochondria make it essential to preserve mitochondrial health in order to maintain cellular activity and liver integrity during liver ischemia/reperfusion (I/R). A growing body of studies suggest that protecting mitochondria by regulating mitochondrial biogenesis, fission/fusion and mitophagy during liver I/R ameliorates LIRI. Targeting mitochondria in conditions that exacerbate mitochondrial dysfunction, such as steatosis and aging, has been successful in decreasing their susceptibility to LIRI. Studying mitochondrial dysfunction will help understand the underlying mechanisms of cellular damage during LIRI which is important for the development of new therapeutic strategies aimed at improving patient outcomes. In this review, we highlight the progress made in recent years regarding the role of mitochondria in liver I/R and discuss the impact of liver conditions on LIRI.

The multifaceted roles of natural products in mitochondrial dysfunction

Mitochondria are the primary source of energy production in cells, supporting the metabolic demand of tissue. The dysfunctional mitochondria are implicated in various diseases ranging from neurodegeneration to cancer. Therefore, regulating dysfunctional mitochondria offers a new therapeutic opportunity for diseases with mitochondrial dysfunction. Natural products are pleiotropic and readily obtainable sources of therapeutic agents, which have broad prospects in new drug discovery. Recently, many mitochondria-targeting natural products have been extensively studied and have shown promising pharmacological activity in regulating mitochondrial dysfunction. Hence, we summarize recent advances in natural products in targeting mitochondria and regulating mitochondrial dysfunction in this review. We discuss natural products in terms of their mechanisms on mitochondrial dysfunction, including modulating mitochondrial quality control system and regulating mitochondrial functions. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products, emphasizing the potential value of natural products in mitochondrial dysfunction.

Nutraceutical activation of Sirt1: a review

The deacetylase sirtuin 1 (Sirt1), activated by calorie restriction and fasting, exerts several complementary effects on cellular function that are favourable to healthspan; it is often thought of as an 'anti-aging' enzyme. Practical measures which might boost Sirt1 activity are therefore of considerable interest. A number of nutraceuticals have potential in this regard. Nutraceuticals reported to enhance Sirt1 synthesis or protein expression include ferulic acid, tetrahydrocurcumin, urolithin A, melatonin, astaxanthin, carnosic acid and neochlorogenic acid. The half-life of Sirt1 protein can be enhanced with the natural nicotinamide catabolite N1-methylnicotinamide. The availability of Sirt1's obligate substrate NAD+ can be increased in several ways: nicotinamide riboside and nicotinamide mononucleotide can function as substrates for NAD+ synthesis; activators of AMP-activated kinase-such as berberine-can increase expression of nicotinamide phosphoribosyltransferase, which is rate limiting for NAD+ synthesis; and nutraceutical quinones such as thymoquinone and pyrroloquinoline quinone can boost NAD+ by promoting oxidation of NADH. Induced ketosis-as via ingestion of medium-chain triglycerides-can increase NAD+ in the brain by lessening the reduction of NAD+ mediated by glycolysis. Post-translational modifications of Sirt1 by O-GlcNAcylation or sulfonation can increase its activity, suggesting that administration of glucosamine or of agents promoting hydrogen sulfide synthesis may aid Sirt1 activity. Although resveratrol has poor pharmacokinetics, it can bind to Sirt1 and activate it allosterically-as can so-called sirtuin-activating compound drugs. Since oxidative stress can reduce Sirt1 activity in multiple ways, effective antioxidant supplementation that blunts such stress may also help preserve Sirt1 activity in some circumstances. Combination nutraceutical regimens providing physiologically meaningful doses of several of these agents, capable of activating Sirt1 in complementary ways, may have considerable potential for health promotion. Such measures may also amplify the benefits of sodium-glucose cotransporter-2 (SGLT2) inhibitors in non-diabetic disorders, as these benefits appear to reflect upregulation of Sirt1 and AMP-activated protein kinase activities.

Emerging Roles of NDUFS8 Located in Mitochondrial Complex I in Different Diseases

NADH:ubiquinone oxidoreductase core subunit S8 (NDUFS8) is an essential core subunit and component of the iron-sulfur (FeS) fragment of mitochondrial complex I directly involved in the electron transfer process and energy metabolism. Pathogenic variants of the NDUFS8 are relevant to infantile-onset and severe diseases, including Leigh syndrome, cancer, and diabetes mellitus. With over 1000 nuclear genes potentially causing a mitochondrial disorder, the current diagnostic approach requires targeted molecular analysis, guided by a combination of clinical and biochemical features. Currently, there are only several studies on pathogenic variants of the NDUFS8 in Leigh syndrome, and a lack of literature on its precise mechanism in cancer and diabetes mellitus exists. Therefore, NDUFS8-related diseases should be extensively explored and precisely diagnosed at the molecular level with the application of next-generation sequencing technologies. A more distinct comprehension will be needed to shed light on NDUFS8 and its related diseases for further research. In this review, a comprehensive summary of the current knowledge about NDUFS8 structural function, its pathogenic mutations in Leigh syndrome, as well as its underlying roles in cancer and diabetes mellitus is provided, offering potential pathogenesis, progress, and therapeutic target of different diseases. We also put forward some problems and solutions for the following investigations.

Berberine mitigates hepatic insulin resistance by enhancing mitochondrial architecture via the SIRT1/Opa1 signalling pathway

The aberrant changes of fussion/fission-related proteins can trigger mitochondrial dynamics imbalance, which cause mitochondrial dysfunctions and result insulin resistance (IR). However, the relationship between the inner mitochondrial membrane fusion protein optic atrophy 1 (Opa1) and hepatic IR as well as the specific molecular mechanisms of signal transduction has not been fully elucidated. In this study, we explore whether abnormalities in the Opa1 cause hepatic IR and whether berberine (BBR) can prevent hepatic IR through the SIRT1/Opa1 signalling pathway. High-fat diet (HFD)-fed mice and db/db mice are used as animal models to study hepatic IR in vivo. IR, morphological changes, and mitochondrial injury of the liver are examined to explore the effects of BBR. SIRT1/Opa1 protein expression is determined to confirm whether the signalling pathway is damaged in the model animals and is involved in BBR treatment-mediated mitigation of hepatic IR. A palmitate (PA)-induced hepatocyte IR model is established in HepG2 cells in vitro. Opa1 silencing and SIRT1 overexpression are induced to verify whether Opa1 deficiency causes hepatocyte IR and whether SIRT1 improves this dysfunction. BBR treatment and SIRT1 silencing are employed to confirm that BBR can prevent hepatic IR by activating the SIRT1/Opa1 signalling pathway. Western blot analysis and JC-1 fluorescent staining results show that Opa1 deficiency causes an imbalance in mitochondrial fusion/fission and impairs insulin signalling in HepG2 cells. SIRT1 and BBR overexpression ameliorates PA-induced IR, increases Opa1, and improves mitochondrial function. SIRT1 silencing partly reverses the effects of BBR on HepG2 cells. SIRT1 and Opa1 expressions are downregulated in the animal models. BBR attenuates hepatic IR and enhances SIRT1/Opa1 signalling in db/db mice. In summary, Opa1 silencing-mediated mitochondrial fusion/fission imbalance could lead to hepatocyte IR. BBR may improve hepatic IR by regulating the SIRT1/Opa1 signalling pathway, and thus, it may be used to treat type-2 diabetes.

Metformin attenuates osteoarthritis by targeting chondrocytes, synovial macrophages and adipocytes

OBJECTIVE

To investigate the therapeutic effect and mechanism of metformin on knee osteoarthritis (OA) in normal diet (ND) mice or high-fat diet (HFD)-induced obese mice.

METHODS

Destabilization of the medial meniscus surgery was performed in ND mice or HFD mice, and metformin was administrated in drinking water or not. The changes of OA joint structure, infiltration and polarization of synovial macrophages and circulating and local levels of leptin and adiponectin were evaluated. In vitro, the effects of metformin on chondrocytes and macrophages, and of conditioned mediums derived from mouse abdominal fat on murine chondrogenic cell line ATDC5 and murine macrophage cell line RAW264.7, were detected.

RESULTS

Metformin showed protective effects on OA, characterized by reductions on OARSI score (2.00, 95% CI [1.15-2.86] for ND mice and 3.17, 95% CI [2.37-3.96] for HFD mice) and synovitis score (1.17, 95% CI [0.27-2.06] for ND mice and 2.50, 95% CI [1.49-3.51] for HFD mice) after 10 weeks of treatment, and the effects were more significant in HFD mice than in ND mice. Mechanistically, in addition to decreasing apoptosis and matrix-degrading enzymes expression in chondrocytes as well as infiltration and pro-inflammatory differentiation of synovial macrophages, metformin reduced leptin secretion by adipose tissue in HFD mice.

CONCLUSIONS

Metformin protects against knee OA which could be through reducing apoptosis and catabolism of chondrocytes, and suppressing infiltration and pro-inflammatory polarization of synovial macrophages. For obese mice, metformin has a greater protective effect in knee OA additionally through reducing leptin secretion from adipose tissue.

Natural products: Potential therapeutic agents to prevent skeletal muscle atrophy

The skeletal muscle (SkM) is the largest organ, which plays a vital role in controlling musculature, locomotion, body heat regulation, physical strength, and metabolism of the body. A sedentary lifestyle, aging, cachexia, denervation, immobilization, etc. Can lead to an imbalance between protein synthesis and degradation, which is further responsible for SkM atrophy (SmA). To date, the understanding of the mechanism of SkM mass loss is limited which also restricted the number of drugs to treat SmA. Thus, there is an urgent need to develop novel approaches to regulate muscle homeostasis. Presently, some natural products attained immense attraction to regulate SkM homeostasis. The natural products, i.e., polyphenols (resveratrol, curcumin), terpenoids (ursolic acid, tanshinone IIA, celastrol), flavonoids, alkaloids (tomatidine, magnoflorine), vitamin D, etc. exhibit strong potential against SmA. Some of these natural products have been reported to have equivalent potential to standard treatments to prevent body lean mass loss. Indeed, owing to the large complexity, diversity, and slow absorption rate of bioactive compounds made their usage quite challenging. Moreover, the use of natural products is controversial due to their partially known or elusive mechanism of action. Therefore, the present review summarizes various experimental and clinical evidence of some important bioactive compounds that shall help in the development of novel strategies to counteract SmA elicited by various causes.

Coenzyme Q10 deficiency can be expected to compromise Sirt1 activity

For reasons that remain unclear, endogenous synthesis and tissue levels of coenzyme Q10 (CoQ10) tend to decline with increasing age in at least some tissues. When CoQ10 levels are sufficiently low, this compromises the efficiency of the mitochondrial electron transport chain, such that production of superoxide by site 2 increases and the rate of adenosine triphosphate production declines. Moreover, CoQ10 deficiency can be expected to decrease activities of Sirt1 and Sirt3 deacetylases, believed to be key determinants of health span. Reduction of the cytoplasmic and mitochondrial NAD+/NADH ratio consequent to CoQ10 deficit can be expected to decrease the activity of these deacetylases by lessening availability of their obligate substrate NAD+ The increased oxidant production induced by CoQ10 deficiency can decrease the stability of Sirt1 protein by complementary mechanisms. And CoQ10 deficiency has also been found to lower mRNA expression of Sirt1. An analysis of the roles of Sirt1/Sirt3 in modulation of cellular function helps to rationalise clinical benefits of CoQ10 supplementation reported in heart failure, hypertension, non-alcoholic fatty liver disease, metabolic syndrome and periodontal disease. Hence, correction of CoQ10 deficiency joins a growing list of measures that have potential for amplifying health protective Sirt1/Sirt3 activities.

Research progress on the pharmacological effects of berberine targeting mitochondria

Berberine is a natural active ingredient extracted from the rhizome of Rhizoma Coptidis, which interacts with multiple intracellular targets and exhibits a wide range of pharmacological activities. Previous studies have preliminarily confirmed that the regulation of mitochondrial activity is related to various pharmacological actions of berberine, such as regulating blood sugar and lipid and inhibiting tumor progression. However, the mechanism of berberine's regulation of mitochondrial activity remains to be further studied. This paper summarizes the molecular mechanism of the mitochondrial quality control system and briefly reviews the targets of berberine in regulating mitochondrial activity. It is proposed that berberine mainly regulates glycolipid metabolism by regulating mitochondrial respiratory chain function, promotes tumor cell apoptosis by regulating mitochondrial apoptosis pathway, and protects cardiac function by promoting mitophagy to alleviate mitochondrial dysfunction. It reveals the mechanism of berberine's pharmacological effects from the perspective of mitochondria and provides a scientific basis for the application of berberine in the clinical treatment of diseases.

Potencjalne możliwości wykorzystania berberyny w przeciwdziałaniu insulinooporności i w cukrzycy typu 2

Insulinooporność to stan zmniejszonej wrażliwości tkanek docelowych na działanie insuliny, mimo jej prawidłowego lub podwyższonego stężenia w surowicy krwi. Jest ważnym czynnikiem w patogenezie zespołu metabolicznego, w tym stanu przedcukrzycowego i cukrzycy typu 2, a także chorób sercowo-naczyniowych oraz zespołu policystycznych jajników. Wzrasta zainteresowanie wykorzystaniem środków pochodzenia roślinnego w leczeniu pacjentów z chorobami metabolicznymi. Jednymi z nich są rośliny z rodziny berberysowatych zawierające alkaloidy izochinolinowe, takie jak berberyna. Sugeruje się, iż berberyna może wpływać na zmniejszenie insulinooporności, gospodarkę węglowodanową oraz metabolizm lipidów. Naukowcy wykazali, że ten roślinny alkaloid może tłumić różnicowanie adipocytów i wspomagać redukcję masy ciała. Inne właściwości berberyny obejmują działanie hipotensyjne oraz ochronne wobec śródbłonka naczyniowego. W artykule skoncentrowano się przede wszystkim na przedstawieniu potencjalnych możliwości wykorzystania berberyny w przeciwdziałaniu insulinooporności w cukrzycy typu 2.

Tibetan Medicine for Diabetes Mellitus: Overview of Pharmacological Perspectives

Diabetes mellitus (DM) and its complications pose a major public health threat which is approaching epidemic proportions globally. Current drug options may not provide good efficacy and even cause serious adverse effects. Seeking safe and effective agents for DM treatment has been an area of intensive interest. As a healing system originating in Tibet, Traditional Tibetan Medicine (TTM) has been widely used by Tibetan people for the prevention and treatment of DM and its complications for hundreds of years. Tibetan Materia Medica (TMM) including the flower of Edgeworthia gardneri (Wall.) Meisn., Phyllanthi Fructus, Chebulae Fructus, Huidouba, and Berberidis Cortex are most frequently used and studied. These TMMs possess hypoglycemic, anti-insulin resistant, anti-glycation, lipid lowering, anti-inflammatory, and anti-oxidative effects. The underlying mechanisms of these actions may be related to their α-glucosidase inhibitory, insulin signaling promoting, PPARs-activating, gut microbiota modulation, islet β cell-preserving, and TNF-α signaling suppressive properties. This review presents a comprehensive overview of the mode and mechanisms of action of various active constituents, extracts, preparations, and formulas from TMM. The dynamic beneficial effects of the products prepared from TMM for the management of DM and its complications are summarized. These TMMs are valuable materia medica which have the potential to be developed as safe and effective anti-DM agents.

Pre- and Post-partum Berberine Supplementation in Dairy Goats as a Novel Strategy to Mitigate Oxidative Stress and Inflammation

As in dairy cattle, goats during the transition period face risk factors, in particular negative energy balance (NEB), inflammation, and impairment of the antioxidant response. The current study determined the effects of pre- and post-partum berberine (BBR) supplementation on antioxidant status and inflammation response during the transition period in dairy goats. Twenty-four primiparous Saanen goats were randomly divided into four groups: control (CON, without BBR) and supplemented with 1 g/day BBR (BBR1), 2 g/day BBR (BBR2), or 4 g/day BBR (BBR4). The blood samples were collected weekly from 21 days pre-partum to 21 days post-partum. Compared with CON, supplementation with either BBR2 or BBR4 decreased (P ≤ 0.05) the levels of plasma non-esterified fatty acids (NEFA) at kidding and thereafter an increased (P ≤ 0.05) the plasma levels of glucose and insulin. Following BBR ingestion, blood antioxidant status elevated throughout the transition period, so that total antioxidant capacity (TAC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase activity were increased (P ≤ 0.05) and plasma malondialdehyde (MDA) was decreased (P ≤ 0.05). Likewise, paraoxonase (PON) was reduced (P ≤ 0.05) in goats fed BBR2 and BBR4. The levels of haptoglobin, ceruloplasmin, and bilirubin were reduced (P ≤ 0.05) by BBR2 and BBR4 immediately before kidding and thereafter. The results demonstrated that supplementation of either 2 or 4 g/day BBR enhanced antioxidant capacity and immune function of transition goats and improved post-partum performance showing its beneficial effect to mitigate oxidative stress and inflammation during the transition period in dairy goats.

Berberine modulates deacetylation of PPARγ to promote adipose tissue remodeling and thermogenesis via AMPK/SIRT1 pathway

Pharmacological stimulation of adipose tissue remodeling and thermogenesis to increase energy expenditure is expected to be a viable therapeutic strategy for obesity. Berberine has been reported to have pharmacological activity in adipose tissue to anti-obesity, while the mechanism remains unclear. Here, we observed that berberine significantly reduced the body weight and insulin resistance of high-fat diet mice by promoting the distribution of brown adipose tissue and thermogenesis. We have further demonstrated that berberine activated energy metabolic sensing pathway AMPK/SIRT1 axis to increase the level of PPARγ deacetylation, which leads to promoting adipose tissue remodeling and increasing the expression of the thermogenic protein UCP-1. These findings suggest that berberine that enhances the AMPK/SIRT1 pathway can act as a selective PPARγ activator to promote adipose tissue remodeling and thermogenesis. This study proposes a new mechanism for the regulation of berberine in adipose tissue and offers a great prospect for berberine in obesity treatment

Dietary Regulation of Oxidative Stress in Chronic Metabolic Diseases

Oxidative stress is a status of imbalance between oxidants and antioxidants, resulting in molecular damage and interruption of redox signaling in an organism. Indeed, oxidative stress has been associated with many metabolic disorders due to unhealthy dietary patterns and may be alleviated by properly increasing the intake of antioxidants. Thus, it is quite important to adopt a healthy dietary mode to regulate oxidative stress and maintain cell and tissue homeostasis, preventing inflammation and chronic metabolic diseases. This review focuses on the links between dietary nutrients and health, summarizing the role of oxidative stress in ‘unhealthy’ metabolic pathway activities in individuals and how oxidative stress is further regulated by balanced diets.

Berberine elevates cardiolipin in heart of offspring from mouse dams with high fat diet-induced gestational diabetes mellitus

Berberine (BBR) is an isoquinoline alkaloid from plants known to improve cardiac mitochondrial function in gestational diabetes mellitus (GDM) offspring but the mechanism is poorly understood. We examined the role of the mitochondrial phospholipid cardiolipin (CL) in mediating this cardiac improvement. C57BL/6 female mice were fed either a Lean-inducing low-fat diet or a GDM-inducing high-fat diet for 6 weeks prior to breeding. Lean and GDM-exposed male offspring were randomly assigned a low-fat, high-fat, or high-fat diet containing BBR at weaning for 12 weeks. The content of CL was elevated in the heart of GDM offspring fed a high fat diet containing BBR. The increase in total cardiac CL was due to significant increases in the most abundant and functionally important CL species, tetralinoleoyl-CL and this correlated with an increase in the expression of the CL remodeling enzyme tafazzin. Additionally, BBR treatment increased expression of cardiac enzymes involved in fatty acid uptake and oxidation and electron transport chain subunits in high fat diet fed GDM offspring. Thus, dietary BBR protection from cardiac dysfunction in GDM exposed offspring involves improvement in mitochondrial function mediated through increased synthesis of CL.

Berberine improves dietary-induced cardiac remodeling by upregulating Kruppel-like factor 4-dependent mitochondrial function

Multiple studies have showed that berberine protects against heart diseases, including obesity-associated cardiomyopathy. However, it is not fully disclosed the potential molecular mechanisms of berberine on controlling cardiac remodeling. Kruppel-like factor (KLF) 4, identified as a critical transcriptional factor, participates in multiple cardiac injuries. The present study was to explore whether KLF4 determined the cardioprotective benefits of berberine in dietary-induced obese mice. High fat diet-induced obese mice were treated with berberine with or without lentivirus encoding Klf4 siRNA, and cardiac parameters were analyzed by multiple biological approaches. In dietary-induced obese mouse model, administration of berberine obviously increased cardiac level of KLF4, which closely correlated with improvement of cardiac functional parameters. Co-treatment of lentivirus encoding Klf4 siRNA abolished cardioprotective benefits of berberine, including induction of cardiac hypertrophy, fibrosis, functional disorders, inflammatory response and oxidative stress. Mechanistically, we found berberine improved cardiac mitochondrial biogenesis and activities, whereas silencing Klf4 decreased berberine-upregulated mitochondrial quality, ATP production and oxygen consumption. Our present study demonstrated that berberine protected against dietary-induced cardiac structural disorders and mitochondrial dysfunction dependent on cardiac KLF4 signaling. Cardiac KLF4 was one of potential therapeutic targets for obesity-induced cardiac injuries.

Berberine improves intralipid-induced insulin resistance in murine

Insulin resistance (IR) is a major metabolic risk factor even before the onset of hyperglycemia. Recently, berberine (BBR) is found to improve hyperglycemia and IR. In this study, we investigated whether BBR could improve IR independent of hyperglycemia. Acute insulin-resistant state was induced in rats by systemic infusion of intralipid (6.6%). BBR was administered via different delivery routes before or after the beginning of a 2-h euglycemic-hyperinsulinemic clamp. At the end of experiment, rats were sacrificed, gastrocnemius muscle was collected for detecting mitochondrial swelling, phosphorylation of Akt and AMPK, as well as the mitochondrial permeability regulator cyclophilin D (CypD) protein expression. We showed that BBR administration markedly ameliorated intralipid-induced IR without affecting blood glucose, which was accompanied by alleviated mitochondrial swelling in skeletal muscle. We used human skeletal muscle cells (HSMCs), AML12 hepatocytes, human umbilical vein endothelial cells, and CypD knockout mice to investigate metabolic and molecular alternations. In either HSMCs or AML12 hepatocytes, BBR (5 μM) abolished palmitate acid (PA)-induced increase of CypD protein levels. In CypD-deficient mice, intralipid-induced IR was greatly attenuated and the beneficial effect of BBR was diminished. Furthermore, we demonstrated that the inhibitory effect of BBR on intralipid-induced IR was mainly mediated by skeletal muscle, but not by intestine, liver, or microvasculature; BBR administration suppressed intralipid-induced upregulation of CypD expression in skeletal muscle. These results suggest that BBR alleviates intralipid-induced IR, which is related to the inhibition of CypD protein expression in skeletal muscle.

Methionine-chelated Zn promotes anabolism by integrating mTOR signal and autophagy pathway in juvenile yellow catfish

BACKGROUND

Amino acid-chelated zinc (Zn) can increase anabolism of animals. However, the underlying mechanisms are unclear. We aimed to examine how autophagy impact anabolism following a diet containing methionine-chelated Zn (ZnMet) compared with inorganic Zn (ZnSO₄).

METHODS

Yellow catfish (weight: 4.02 ± 0.08 g) were fed two diets containing ZnSO₄ or ZnMet for 8 wk. The differences in transcriptional responses and corresponding biological profiles were compared between the livers of fish fed the two Zn sources of diets. Hepatocytes of yellow catfish were incubated for 48 h in medium containing ZnSO₄ (10 μM ZnSO₄) or ZnMet (10 μM ZnMet) after 2 h pretreated with or without pathway inhibitors. Intracellular Zn, TG and protein contents, lipid droplet and autophagic vesicles were detected. Ultrastructural observation, enzymatic activities, qPCR assays, western blot and immunofluorescence analysis were conducted.

RESULTS

ZnMet up-regulated the expression of genes associated with anabolism and autophagy. The differentially expressed genes (DEG) analysis indicated that both mTOR and autophagy pathways were activated. ZnMet-induced activation of autophagy was mTOR-independent. In this process, forkhead box class O was deacetylated and activated, and induced autophagy, which provided substrates for energy generation.

CONCLUSIONS

ZnMet increased anabolism through integrating mTOR signal and autophagy pathway in yellow catfish. The present study unravels a novel mechanism for amino acid-chelated minerals improving anabolism.

Supplemental Berberine in a High-Fat Diet Reduces Adiposity and Cardiac Dysfunction in Offspring of Mouse Dams with Gestational Diabetes Mellitus

BACKGROUND

There are few evidence-based strategies to attenuate the risk of metabolic syndrome in offspring exposed to gestational diabetes mellitus (GDM). Berberine (BBR) is an isoquinoline alkaloid extracted from Chinese herbs and exhibits glucose lowering properties.

OBJECTIVES

We hypothesized that dietary BBR would improve health outcomes in the mouse offspring of GDM dams.

METHODS

Wild-type C57BL/6 female mice were fed either a Lean-inducing low-fat diet (L-LF,10% kcal fat, 35% kcal sucrose) or a GDM-inducing high-fat diet (GDM-HF, 45% kcal fat, 17.5% sucrose) for 6 wk prior to breeding with wild-type C57BL/6 male mice throughout pregnancy and the suckling period. The resulting Lean and GDM-exposed male and female offspring were randomly assigned an LF (10% kcal fat, 35% kcal sucrose), HF (45% kcal fat, 17.5% sucrose), or high-fat berberine (HFB) (45% kcal fat, 17.5% sucrose diet) containing BBR (160 mg/kg/d, HFB) at weaning for 12 wk. The main outcome was to evaluate the effects of BBR on obesity, pancreatic islet function, and cardiac contractility in GDM-exposed HF-fed offspring. Significance between measurements was determined using a 2 (gestational exposure) × 3 (diet) factorial design by a 2- way ANOVA using Tukey post-hoc analysis.

RESULTS

In the GDM-HF group, body weights were significantly increased (16%) compared with those in baseline (L-LF) animals (P < 0.05). Compared with the L-LF animals, the GDM-HF group had a reduction in pancreatic insulin glucose-stimulated insulin secretion (74%) and increased cardiac isovolumetric contraction time (IVCT; ∼150%) (P < 0.05). Compared with GDM-HF animals, the GDM-HFB group with the dietary addition of BBR had significantly reduced body weight (16%), increased glucose-stimulated insulin secretion from pancreatic islets (254%), and reduced systolic heart function (46% IVCT) (P < 0.05).

CONCLUSIONS

In a mouse model of GDM, dietary BBR treatment provided protection from obesity and the development of pancreatic islet and cardiac dysfunction.

Mitochondrial Bioenergetic Assays as a Standard Protocol for Toxicological and Metabolic Assessment

Mitochondria are the center for all metabolic pathways within the eukaryotic cell. Being responsible for the production of over 95% of the cell's requirement of adenosine triphosphate any effect on the function of mitochondria is sure to cause disruption of cellular activity and even viability. As such, it comes as no surprise that many diseases have mitochondrial dysfunction at their core. Understanding mitochondrial function and capacity in the context of a study is key for perceiving and explaining the behavior of said disease or toxic effect. Here, we describe a wide array of simple and yet elegant assays that can be easily implemented to ascertain the function of mitochondria and thus greatly improve the understanding of how a certain disease or compound causes its effects on the cellular function.

Synergy Effects of Metformin and Berberine on Glyoxal-induced Carbonyl Stress in Isolated Rat Liver Mitochondria

Objective:

Carbonyl stress, resulting from toxic effects of alpha-dicarbonyls such as glyoxal (GO), plays an important role in mitochondrial dysfunction and subsequent development of diabetic complications. This study evaluated the ability of metformin (MET), berberine (BBR), and their combination to prevent GO-induced carbonyl stress in isolated rat liver mitochondria.

Methods:

Mitochondria (0.5 mg protein/mL) were isolated from the Wistar rat liver and incubated with various concentrations of GO (1, 2.5, 5, 7.5, and 10 mM) for 30 minutes and IC50 for GO was calculated. The suspensions of mitochondria were incubated with various concentrations of MET (2.5, 5, 10, and 20 mM) or BBR (2.5, 5, 10, and 20 μM) for 30 min and then GO in a dose of IC50 at 37 ºC for 30 min. Mitochondrial complex II activity, mitochondrial membrane potential (MMP), MDA level, reactive oxygen species (ROS) formation, reduced glutathione (GSH) content, and protein carbonylation were assessed. The combination index and isobologram of MET and BBR on GO toxicity were calculated.

Results:

IC50 of GO was assigned approximately 3 mM. GO disrupted the electron transfer chain and significantly increased mitochondrial ROS formation, protein carbonylation, and MDA level. GO decreased mitochondrial viability, MMP, and GSH content. Pre-treatment with MET and BBR could potentially reverse GO-induced deleterious effects in a concentration-dependent manner. Results of the drug combination indicated that CI for Fa 0.5 (Effect 50 %) was 0.83.

Conclusion:

These results suggest that BBR in combination with MET has a moderate synergistic effect on GO-induced carbonyl stress in isolated rat liver mitochondria.

Berberine Ameliorates Hepatic Insulin Resistance by Regulating microRNA-146b/SIRT1 Pathway

OBJECTIVE

Hepatic insulin resistance is a major initiating factor for type 2 diabetes mellitus. In previous study, Gegen Qinlian Decoction containing berberine could enhance hepatic insulin sensitivity by SIRT1-dependent deacetylation of FOXO1. However, it is not clear whether berberine also can improve hepatic insulin sensitivity by SIRT1/FOXO1 pathway. This study aimed to evaluate the efficacy of berberine for improving hepatic insulin resistance and the possible molecular mechanisms involved.

METHODS

In vitro, HepG2 cells were induced with palmitic acid, and glycogen synthesis was examined. In vivo, a high-fat diet (HFD)-fed mouse model was established, and metabolic parameters were assessed. The expressions of miR-146b and sirtuin 1 (SIRT1) in liver were also examined. The relationship between miR-146b and SIRT1 was examined by the dual-luciferase reporter gene assay.

RESULTS

Serum biochemical parameters, such as glucose and HOMA-IR index, were increased in HFD mice; miR-146b and SIRT1 were abnormally expressed in HFD mice and palmitic acid-treated HepG2 cells. Interestingly, berberine reduced body weight and caused a significant improvement in glucose tolerance and HOMA-IR index without altering food intake in mice. Overexpression of miR-146b abolished the protective effect of berberine on palmitic acid-induced impaired glycogen synthesis in HepG2 cells. Luciferase assay showed that miR-146b directly targeted SIRT1.

CONCLUSION

The present findings suggest that berberine could attenuate hepatic insulin resistance through the miR-146b/SIRT1 pathway, which may represent a potential therapeutic target for the prevention and treatment of metabolic diseases, particularly diabetes.

Berberine protects human and rat cardiomyocytes from hypoxia/reoxygenation-triggered apoptosis

Berberine (BBR) confers potential cardioprotective effects. However, the relevant mechanisms underlying its regulation of cardiomyocyte survival following hypoxia/reoxygenation (H/R) treatment remain unknown. The present study investigated whether BBR could protect H/R by suppressing apoptosis and explored how TGF-β/Smad4 signaling pathway influenced H/R in vitro. Two cardiomyocyte cell lines-AC16 and H9c2- were treated with H/R and BBR. The survival and apoptosis of these two cell lines were assessed using the MTT and BrdU assays and western blotting (WB) and flow cytometry. Mitochondrial reactive oxygen species (ROS) and caspase (Cas)-3, Cas-8, and Cas-9 activation were evaluated using enzyme-linked immunosorbent assay as well as WB. Compared to the control group, H/R resulted in notable cell apoptosis, whereas BBR treatment evidently counteracted the process. BBR also markedly suppressed H/R-triggered excessive mitochondrial ROS generation and inhibited Smad4 expression. Overexpressing Smad4 in BBR-treated H/R-exposed cardiomyocytes reversed the effect of BBR treatment on apoptosis. Therefore, BBR protects H/R-treated cardiomyocytes from apoptosis by inhibiting the TGF-β/Smad4 signaling pathway.

Huang Lian Jie Du Tang attenuates paraquat-induced mitophagy in human SH-SY5Y cells: A traditional decoction with a novel therapeutic potential in treating Parkinson's disease

Huang Lian Jie Du Tang (HLJDT) is a traditional Chinese medical decoction for heat-fire clearing and detoxication. Theoretically, the cause of Parkinson's disease (PD) has been attributed to the dysregulations of internal wind, phlegm, fire, and stasis. Thus, HLJDT has been used to treat PD. However, the molecular mechanism is unknown. Besides, paraquat (PQ) as an herbicide has been known to impair midbrain dopaminergic neurons, resemblance to the pathology of PD. Thus, the molecular mechanism of HLJDT in treating PD and PQ-induced in vitro PD model was investigated in this study. Primarily, the dose-response of PQ (0.1∼1 mM)-induced neurotoxicity for 24 h was performed in the human neuroblastoma SH-SY5Y cells. The LD₅₀ of PQ is around 0.3 mM and was applied throughout the following experiments. The neutral red assay was used to estimate cell viability. Co-transfection of the mitochondrial marker and proapoptotic factor genes were applied to measure the release of mitochondrial proapoptotic factors during PQ intoxication and HLJDT protection. The fluorescent dyes were used to detect mitochondrial membrane potential and free radical formation. Western blot and dot-blot analysis and immunocytochemistry were used to estimate the level of proteins related to apoptosis and mitophagy. PINK1 gene silencing was used to determine the significance of mitophagy during PQ intoxication. In this study, HLJDT attenuated PQ-induced apoptosis in SH-SY5Y cells. HLJDT reversed PQ-induced decreased mitochondrial membrane potential and suppressed PQ-induced increased cytosolic and mitochondrial free radical formations and mitochondrial proapoptotic factor releases. Furthermore, HLJDT mitigated PQ-induced increases in full-length PINK1, phosphorylations of Parkin and ubiquitin, mitochondrial translocation of phosphorylated Parkin, and mitophagy. PINK1 gene silencing attenuated PQ-induced neurotoxicity. Therefore, HLJDT attenuated PQ-induced cell death by regulating mitophagy.

Adipose Tissue SIRT1 Regulates Insulin Sensitizing and Anti-Inflammatory Effects of Berberine

Berberine (BBR), which is an active component of Coptis chinensis Franch, has been reported to improve glucose metabolism and insulin resistance in animal and human studies, predominantly via activation of the 5′-adenosine monophosphate kinase (AMPK) pathway and suppression of the inflammation response. However, the mechanisms underlying the effects of BBR on AMPK and inflammation remain unclear. In this present study, we found that BBR upregulated SIRT1 expression in 3T3L-1 adipocytes and adipose tissue. Inhibition of SIRT1 blunted the BBR-induced increase in glucose consumption and uptake in adipocytes. The BBR-induced activation of the AMPK pathway and AKT phosphorylation in adipocytes and adipose tissue were also attenuated by inhibition or knockout of Sirt1. The BBR-induced improvement of systemic insulin sensitivity was impaired by Sirt1 knockout in HFD-induced obese mice. The suppressing effects of BBR on systemic and local inflammatory responses, such as serum concentrations and expression of inflammatory cytokines, phosphorylation of c-Jun N-terminal kinase (JNK) and IKKβ, and the accumulation of F4/80-positive macrophages in adipose tissue were also attenuated in Sirt1 knockout mice. The BBR-induced decrease in PGC-1α acetylation was reversed by inhibition or knockout of Sirt1 in adipocytes and adipose tissue. Together, these results indicate that adipose tissue SIRT1 is a key regulator of the insulin sensitizing and anti-inflammatory effects of BBR, which contributes to the improvement of metabolic dysregulation.

Exploiting Common Aspects of Obesity and Alzheimer's Disease

Alzheimer’s disease (AD) is an example of age-related dementia, and there are still no known preventive or curative measures for this disease. Obesity and associated metabolic changes are widely accepted as risk factors of age-related cognitive decline. Insulin is the prime mediator of metabolic homeostasis, which is impaired in obesity, and this impairment potentiates amyloid-β (Aβ) accumulation and the formation of neurofibrillary tangles (NFTs). Obesity is also linked with functional and morphological alterations in brain mitochondria leading to brain insulin resistance (IR) and memory deficits associated with AD. Also, increased peripheral inflammation and oxidative stress due to obesity are the main drivers that increase an individual’s susceptibility to cognitive deficits, thus doubling the risk of AD. This enhanced risk of AD is alarming in the context of a rapidly increasing global incidence of obesity and overweight in the general population. In this review, we summarize the risk factors that link obesity with AD and emphasize the point that the treatment and management of obesity may also provide a way to prevent AD.

Berberine Promotes Cardiac Function by Upregulating PINK1/Parkin-Mediated Mitophagy in Heart Failure

Berberine has been verified to protect cardiac function in patients with heart failure (HF). However, the mechanism(s) involved in berberine-mediated cardioprotective effects has not been clearly elucidated. The aim of this study was to further investigate the mechanism(s) involved in the beneficial effects of berberine on transverse aortic contraction (TAC)-induced chronic HF. Mice were randomly divided into four groups. Berberine was administered at a dose of 50 mg/kg/day for 4 weeks via oral gavage. Our findings showed that TAC-induced pressure overload (PO) prompted cardiac dysfunction, cardiac hypertrophy, interstitial fibrosis, cardiomyocyte apoptosis and mitochondrial injury, accompanied with suppressed mitophagy, the effects of which were attenuated by berberine. Furthermore, mitophagy regulators PINK1 and mito-Parkin were downregulated in TAC-induced HF, while berberine upregulated PINK1/Parkin-mediated mitophagy. Notably, knockdown of PINK1 by small interfering RNA significantly suppressed Parkin-mediated mitochondrial ubiquitination and nullified the beneficial actions on HF exerted by berberine. Taken together, our results indicated that berberine plays a critical role in attenuating cardiac hypertrophy and preserving cardiac function from PO induced HF. The potential underlying mechanism is the activation of mitochondrial autophagy via PINK1/Parkin/Ubiquitination pathway.

Disease-specific phenotypes in iPSC-derived neural stem cells with POLG mutations

Mutations in POLG disrupt mtDNA replication and cause devastating diseases often with neurological phenotypes. Defining disease mechanisms has been hampered by limited access to human tissues, particularly neurons. Using patient cells carrying POLG mutations, we generated iPSCs and then neural stem cells. These neural precursors manifested a phenotype that faithfully replicated the molecular and biochemical changes found in patient post‐mortem brain tissue. We confirmed the same loss of mtDNA and complex I in dopaminergic neurons generated from the same stem cells. POLG‐driven mitochondrial dysfunction led to neuronal ROS overproduction and increased cellular senescence. Loss of complex I was associated with disturbed NAD⁺ metabolism with increased UCP2 expression and reduced phosphorylated SirT1. In cells with compound heterozygous POLG mutations, we also found activated mitophagy via the BNIP3 pathway. Our studies are the first that show it is possible to recapitulate the neuronal molecular and biochemical defects associated with POLG mutation in a human stem cell model. Further, our data provide insight into how mitochondrial dysfunction and mtDNA alterations influence cellular fate determining processes.

Protective role of mitoquinone against impaired mitochondrial homeostasis in metabolic syndrome

Mitochondria control various processes in cellular metabolic homeostasis, such as adenosine triphosphate production, generation and clearance of reactive oxygen species, control of intracellular Ca²⁺ and apoptosis, and are thus a critical therapeutic target for metabolic syndrome (MetS). The mitochondrial targeted antioxidant mitoquinone (MitoQ) reduces mitochondrial oxidative stress, prevents impaired mitochondrial dynamics, and increases mitochondrial turnover by promoting autophagy (mitophagy) and mitochondrial biogenesis, which ultimately contribute to the attenuation of MetS conditions, including obesity, insulin resistance, hypertension and cardiovascular disease. The regulatory effect of MitoQ on mitochondrial homeostasis is mediated through AMPK and its downstream signaling pathways, including MTOR, SIRT1, Nrf2 and NF-κB. However, there are few reviews focusing on the critical role of MitoQ as a therapeutic agent in the treatment of MetS. The purpose of this review is to summarize the mitochondrial role in the pathogenesis of MetS, especially in obesity and type 2 diabetes, and discuss the effect and underlying mechanism of MitoQ on mitochondrial homeostasis in MetS.

Berberine Improves Inflammatory Responses of Diabetes Mellitus in Zucker Diabetic Fatty Rats and Insulin-Resistant HepG2 Cells through the PPM1B Pathway

Berberine (BBR), a natural compound extracted from a Chinese herb, has been shown to effectively attenuate insulin resistance (IR) and inflammation in the clinic. However, its ameliorative mechanism against IR is not well defined. This study is aimed at investigating the effect of BBR and protein phosphatase, Mg²⁺/Mn²⁺-dependent 1B (PPM1B) on IR. Biochemical measurements and liver histopathology were detected using the biochemical analyzer and HE staining in ZDF rats, respectively. Microarray analysis of liver tissues was performed, and differentially expressed gene (DEG) levels were examined by quantitative real-time PCR (qPCR) and Western blot. Additionally, the effect of BBR was also explored in HepG2-IR cells. The glucose oxidase method and the fluorescent glucose analog were used to detect glucose consumption and uptake, respectively. The PKA inhibitor H89, ELISA, qPCR, Western blot, and immunofluorescence staining were employed to estimate the expression levels of related signaling pathways. To evaluate the roles of PPM1B, HepG2-IR cells were stably infected with lentivirus targeting PPM1B. The administration of BBR drastically decreased the body weight, urine volume, blood glucose, blood urea nitrogen (BUN), CHOL, hepatic index levels, and pathologic changes and improved ALB levels in ZDF rats with PPM1B upregulation. Furthermore, BBR effectively improves glucose consumption, uptake, and inflammation in HepG2-IR cells. The knockdown of PPM1B expression aggravated the inflammatory response and glycometabolism disorder in HepG2-IR cells. Mechanistically, a reversal in the expression of cAMP, PKA, PPM1B, PPARγ, LRP1, GLUT4, NF-κB p65, JNK, pIKKβ Ser181, IKKβ, IRS-1 Ser307, IRS-1, IRS-2 Ser731, IRS-2, PI3K p85, and AKT Ser473 contributes to ameliorate IR in HepG2-IR cells with BBR treatment. Altogether, these results suggest that BBR might regulate IR progression through the regulation of the cAMP, PKA, PPM1B, PPARγ, LRP1, GLUT4, NF-κB p65, JNK, pIKKβ Ser181, IKKβ, IRS-1 Ser307, IRS-1, IRS-2 Ser731, IRS-2, PI3K p85, and AKT Ser473 expression in the liver.

G-quadruplex-mediated reduction of a pathogenic mitochondrial heteroplasmy

Disease-associated variants in mitochondrial DNA (mtDNA) are frequently heteroplasmic, a state of co-existence with the wild-type genome. Because heteroplasmy correlates with the severity and penetrance of disease, improvement in the ratio between these genomes in favor of the wild-type, known as heteroplasmy shifting, is potentially therapeutic. We evaluated known pathogenic mtDNA variants and identified those with the potential for allele-specific differences in the formation of non-Watson-Crick G-quadruplex (GQ) structures. We found that the Leigh syndrome (LS)-associated m.10191C variant promotes GQ formation within local sequence in vitro. Interaction of this sequence with a small molecule GQ-binding agent, berberine hydrochloride, further increased GQ stability. The GQ formed at m.10191C differentially impeded the processivity of the mitochondrial DNA polymerase gamma (Pol γ) in vitro, providing a potential means to favor replication of the wild-type allele. We tested the potential for shifting heteroplasmy through the cyclical application of two different mitochondria-targeted GQ binding compounds in primary fibroblasts from patients with m.10191T>C heteroplasmy. Treatment induced alternating mtDNA depletion and repopulation and was effective in shifting heteroplasmy towards the non-pathogenic allele. Similar treatment of pathogenic heteroplasmies that do not affect GQ formation did not induce heteroplasmy shift. Following treatment, heteroplasmic m.10191T>C cells had persistent improvements and heteroplasmy and a corresponding increase in maximal mitochondrial oxygen consumption. This study demonstrates the potential for using small-molecule GQ-binding agents to induce genetic and functional improvements in m.10191T>C heteroplasmy.

miR-378a: a new emerging microRNA in metabolism

Metabolic diseases, such as type 2 diabetes or obesity, are the consequence of the disruption of the organism's metabolic pathways. The discovery of small non-coding RNAs-microRNAs (miRNAs)-as post-transcriptional gene regulators opened new doors for the development of novel strategies to combat said diseases. The two strands of miR-378a, miR-378a-3p, and miR-378a-5p are encoded in the Ppargc1b gene and have an active role in the regulation of several metabolic pathways such as mitochondrial metabolism and autophagy. Recent studies recognized miR-378a as an important regulator of energy and glucose homeostasis, highlighting it as a potential target for the improvement of metabolic dysregulation. In the present review, the current knowledge on miR-378a will be discussed with a particular emphasis on its biological functions and mechanisms of action in metabolism, mitochondria, and autophagy.

Phytopharmacology and Clinical Updates of Berberis Species Against Diabetes and Other Metabolic Diseases

The incidences of diabetic mellitus and other metabolic diseases such as hypertension and hyperlipidemia are increasing worldwide; however, the current treatment is not able to control the rapidly increasing trend in diabetes mortality and morbidity. Studies related to the effectiveness of extracts and pure compounds obtained from plants have shown promising responses in preclinical and clinical studies related to these metabolic diseases. Plants belonging to the genus Berberis (Family: Berberidaceae) are widely distributed with nearly 550 species worldwide. Extracts and compounds obtained from Berberis species, especially Berberine alkaloid, showed effectiveness in the management of diabetes and other metabolic diseases. Various pharmacological experiments have been performed to evaluate the effects of Berberis extracts, berberine, and its natural and chemically synthesized derivatives against various cell and animal disease models with promising results. Various clinical trials conducted so far also showed preventive effects of Berberis extracts and berberine against metabolic diseases. The present review focuses on i) research updates on traditional uses, ii) phytopharmacology and clinical studies on Berberis species, and iii) active metabolites in the prevention and treatment of diabetes and other metabolic diseases with a detailed mechanism of action. Furthermore, the review critically analyzes current research gaps in the therapeutic use of Berberis species and berberine and provides future recommendations.

Alteration in iron efflux affects male sex hormone testosterone biosynthesis in a diet-induced obese rat model

This study was motivated by clinical observations that dysmetabolic iron overload syndrome (DIOS) and an androgen deficiency are common features observed in obese adult men; however, the molecular mechanism underlying the effects of DIOS on androgen deficiency remains to be elucidated. We established a DIOS animal model by feeding Sprague-Dawley rats an iron/fat-enriched diet (50% fat plus 0.25, 1, or 2 g ferric iron per kg diet) for 12 weeks to induce iron dysfunction (indicated by decreased tissue iron efflux) in obese rats. Obese rats fed an iron/fat-enriched diet showed decreased levels of testicular total Testosterone (T) and iron exporter ferroportin but increased levels of testicular iron and hepcidin, and these effects were more evident with a >1 g ferric iron per kg diet. A western blot analysis showed that an iron/fat-enriched diet triggered testicular endoplasmic reticular (ER) stress but decreased mitochondrion biogenesis proteins (PGC1α and TFAM) and T-converting proteins (StAR, CYP11A, and 17β-HSD). TUNEL staining showed that >1 g ferric iron induced apoptosis mainly in germ cells and Leydig's cells. Uncontrolled testicular iron efflux may cause mitochondrial-ER dysfunction and affect T biosynthesis. Future study targeting the testicular hepcidin-ferroportin axis may offer a therapeutic tool to alleviate testicular iron retention and mitochondrial-ER stress in Leydig's cells.

Resveratrol improves left ventricular remodeling in chronic kidney disease via Sirt1-mediated regulation of FoxO1 activity and MnSOD expression

Left ventricular remodeling commonly complicates end-stage renal disease following chronic kidney disease (CKD). This study investigated the therapeutic efficacy of resveratrol (RSV), a polyphenolic compound, on left ventricular remodeling in subtotal nephrectomy rats and sought to uncover the underlying molecular mechanisms. Subtotal nephrectomy caused renal dysfunction, such as gradual increases in serum creatinine and blood urea nitrogen, glomerular sclerosis, and tubulointerstitial fibrosis. In addition, subtotal nephrectomy also resulted in significant increases in myocyte cross-sectional area, interstitial and perivascular fibrosis, and left ventricular dilatation. All these detrimental effects were alleviated in the presence of RSV. Mechanistically, RSV treatment led to the upregulation of manganese-containing superoxide dismutase (MnSOD) in the heart. Coimmunoprecipitation studies showed that silent information regulator 1 (Sirt1) bound forkhead box protein O1 (FoxO1) and thus reduced acetylated FoxO1. RSV strengthened this interaction between Sirt1 and FoxO1. Loss of one allele of Sirt1 aggravated renal damage, myocyte hypertrophy, and interstitial fibrosis in nephrectomized mice. Taken together, our data show that Sirt1 is an important mediator for the protective roles of RSV on renal and heart damage in CKD rodent model, and FoxO1 and MnSOD are likely downstream targets of Sirt1. Therefore, Sirt1 might be a potential therapeutic target for the treatment of left ventricular remodeling caused by CKD.

Berberine Ameliorates Doxorubicin-Induced Cardiotoxicity via a SIRT1/p66Shc-Mediated Pathway

Doxorubicin- (DOX-) induced cardiotoxicity is associated with oxidative stress and cardiomyocyte apoptosis. The adaptor protein p66Shc regulates the cellular redox status and determines cell susceptibility to apoptosis. This study is aimed at investigating the involvement of sirtuin 1- (SIRT1-) mediated p66Shc inhibition in DOX-induced redox signalling and exploring the possible protective mechanisms of berberine (Ber) against DOX-triggered cardiac injury in rats and a cultured H9c2 cell line. Our results showed that the Ber pretreatment markedly increased CAT, SOD, and GSH-PX activities, decreased the levels of MDA, and improved the electrocardiogram and histopathological changes in the myocardium in DOX-treated rats (in vivo). Furthermore, Ber significantly ameliorated the DOX-induced oxidative insult and mitochondrial damage by adjusting the levels of intracellular ROS, ΔΨ_m, and [Ca²⁺]_m in H9c2 cells (in vitro). Importantly, the Ber pretreatment increased SIRT1 expression following DOX exposure but downregulated p66Shc. Consistent with the results demonstrating the SIRT1-mediated inhibition of p66Shc expression, the Ber pretreatment inhibited DOX-triggered cardiomyocyte apoptosis and mitochondrial dysfunction. After exposing H9c2 cells to DOX, the increased SIRT1 expression induced by Ber was abrogated by a SIRT1-specific inhibitor (EX527) or the use of siRNA against SIRT1. Accordingly, SIRT1 inhibition significantly abrogated the suppression of p66Shc expression and protection of Ber against DOX-induced oxidative stress and apoptosis. These results suggest that Ber protects the heart from DOX injury through SIRT1-mediated p66Shc suppression, offering a novel mechanism responsible for the protection of Ber against DOX-induced cardiomyopathy.