Mitochondria as chi

Bu zhong Yiqi Decoction ameliorates mild cognitive impairment by improving mitochondrial oxidative stress damage via the SIRT3/MnSOD/OGG1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bu-Zhong-Yi-Qi Decoction(BZYQD) is a traditional formula commonly used in China, known for its effects in tonifying Qi and raising Yang. It can relieve symptoms of cognitive impairment such as forgetfulness and lack of concentration caused by qi deficiency, which is common in aging and debilitating. However, much of the current research on BZYQD has been focused on its impact on the digestive system, leaving its molecular mechanisms in improving cognitive function largely unexplored.

AIM OF THE STUDY

Cognitive decline in the aging central nervous system is intrinsically linked to oxidative damage. This study aims to investigate the therapeutic mechanism of BZYQD in treating mild cognitive impairment caused by qi deficiency, particularly through repair of mitochondrial oxidative damage.

MATERIALS AND METHODS

A rat model of mild cognitive impairment (MCI) was established by administering reserpine subcutaneously for two weeks, followed by a two-week treatment with BZYQD/GBE. In vitro experiments were conducted to assess the effects of BZYQD on neuronal cells using a H2O2-induced oxidative damage model in PC12 cells. The open field test and the Morris water maze test evaluated the cognitive and learning memory abilities of the rats. HE staining and TEM were employed to observe morphological changes in the hippocampus and its mitochondria. Mitochondrial activity, ATP levels, and cellular viability were measured using assay kits. Protein expression in the SIRT3/MnSOD/OGG1 pathway was analyzed in tissues and cells through western blotting. Levels of 8-OH-dG in mitochondria extracted from tissues and cells were quantified using ELISA. Mitochondrial morphology in PC12 cells was visualized using Mito Red, and mitochondrial membrane potential was assessed using the JC-1 kit.

RESULTS

BZYQD treatment significantly improved cognitive decline caused by reserpine in rats, as well as enhanced mitochondrial morphology and function in the hippocampus. Our findings indicate that BZYQD mitigates mtDNA oxidative damage in rats by modulating the SIRT3/MnSOD/OGG1 pathway. In PC12 cells, BZYQD reduced oxidative damage to mitochondria and mtDNA in H2O2-induced conditions and was associated with changes in the SIRT3/MnSOD/OGG1 pathway.

CONCLUSION

BZYQD effectively counteracts reserpine-induced mild cognitive impairment and ameliorates mitochondrial oxidative stress damage through the SIRT3/MnSOD/OGG1 pathway.

Validation of mitochondrial biomarkers and immune dynamics in polycystic ovary syndrome

PROBLEM

Polycystic ovary syndrome (PCOS), a prevalent endocrine-metabolic disorder, presents considerable therapeutic challenges due to its complex and elusive pathophysiology.

METHOD OF STUDY

We employed three machine learning algorithms to identify potential biomarkers within a training dataset, comprising GSE138518, GSE155489, and GSE193123. The diagnostic accuracy of these biomarkers was rigorously evaluated using a validation dataset using area under the curve (AUC) metrics. Further validation in clinical samples was conducted using PCR and immunofluorescence techniques. Additionally, we investigate the complex interplay among immune cells in PCOS using CIBERSORT to uncover the relationships between the identified biomarkers and various immune cell types.

RESULTS

Our analysis identified ACSS2, LPIN1, and NR4A1 as key mitochondria-related biomarkers associated with PCOS. A notable difference was observed in the immune microenvironment between PCOS patients and healthy controls. In particular, LPIN1 exhibited a positive correlation with resting mast cells, whereas NR4A1 demonstrated a negative correlation with monocytes in PCOS patients.

CONCLUSION

ACSS2, LPIN1, and NR4A1 emerge as PCOS-related diagnostic biomarkers and potential intervention targets, opening new avenues for the diagnosis and management of PCOS.

Arsenic-Induced Cardiovascular Diseases and their Correlation with Mitochondrial DNA Copy Number, Deletion, and Telomere Length in Bangladeshi Population

Arsenic contamination is a global health concern, primarily through contaminated groundwater and its entry into the food chain. The association between arsenic exposure and cardiovascular diseases (CVDs) is particularly alarming due to CVDs being the leading cause of death worldwide. Arsenic exposure has also been linked to changes in telomere length, mitochondrial DNA copy number (mtDNAcn), and deletion, further increasing the risk of CVDs. We aimed to determine whether arsenic exposure alters telomere length and mtDNAcn and deletion in a total of 50 CVD patients who underwent open heart surgery hailed from known arsenic-affected and unaffected areas in Bangladesh. Amount of arsenic was determined from the collected nails and cardiac tissues. Relative telomere length and mtDNAcn and deletion were quantified by qRT-PCR. The patients from arsenic-contaminated areas had higher average arsenic deposits in their fingers and toenails (P < 0.05) and higher cardiac tissue injury scores (P < 0.05). Moreover, approximately 1.5-fold shorter telomere length (P < 0.05, r =  - 0.775), 1.2-fold decreased mtDNAcn (P < 0.05, r = - 0.797), and an 81-fold higher amount of mitochondrial DNA deletion (P < 0.05, r = 0.784) were observed in the patients who had higher arsenic deposition in their nails. Higher levels of arsenic exposure were found to be linked to shorter telomere length, decreased mtDNAcn, and increased mitochondrial DNA deletion in the patients from As-affected areas. It can also be anticipated that the correlation of arsenic exposure with telomere length, mtDNAcn, and deletion can be used as biomarkers for early diagnosis of arsenic-induced cardiovascular diseases.

Mitochondria as the Essence of Yang Qi in the Human Body

The concept of Yang Qi in Traditional Chinese Medicine (TCM) has many similarities with mitochondria in modern medicine. Both are indispensable to human beings and closely related to life and death. This article discusses the similarities in various aspects between mitochondria and Yang Qi, including body temperature, aging, newborns, circadian rhythm, immunity, and meridian. It is well-known that Yang Qi is vital for human health. Interestingly, decreased mitochondrial function is thought to be key to the development of various diseases. Here, we further explain diseases induced by Yang Qi deficiency, such as cancer, chronic fatigue syndrome, sleep disorder, senile dementia, and metabolic diseases, from the perspective of mitochondrial function. We aim to establish similarities and connections between two important concepts, and hope our essay can stimulate further discussion and investigation on unifying important concepts in western medicine and alternative medicine, especially TCM, and provide unique holistic insights into understanding human health.

Mechanisms of Mitochondrial Malfunction in Alzheimer’s Disease: New Therapeutic Hope

Mitochondria play a critical role in neuron viability or death as it regulates energy metabolism and cell death pathways. They are essential for cellular energy metabolism, reactive oxygen species production, apoptosis, Ca⁺⁺ homeostasis, aging, and regeneration. Mitophagy and mitochondrial dynamics are thus essential processes in the quality control of mitochondria. Improvements in several fundamental features of mitochondrial biology in susceptible neurons of AD brains and the putative underlying mechanisms of such changes have made significant progress. AD's etiology has been reported by mitochondrial malfunction and oxidative damage. According to several recent articles, a continual fusion and fission balance of mitochondria is vital in their normal function maintenance. As a result, the shape and function of mitochondria are inextricably linked. This study examines evidence suggesting that mitochondrial dysfunction plays a significant early impact on AD pathology. Furthermore, the dynamics and roles of mitochondria are discussed with the link between mitochondrial malfunction and autophagy in AD has also been explored. In addition, recent research on mitochondrial dynamics and mitophagy in AD is also discussed in this review. It also goes into how these flaws affect mitochondrial quality control. Furthermore, advanced therapy techniques and lifestyle adjustments that lead to improved management of the dynamics have been demonstrated, hence improving the conditions that contribute to mitochondrial dysfunction in AD.

Next-Generation Sequencing to Characterize Mitochondrial Genomic DNA Heteroplasmy

Mitochondria play a very important role in many crucial cellular functions. Each eukaryotic cell contains hundreds of mitochondria with hundreds of mitochondrial genomes. Mutant and wild-type mitochondrial DNA (mtDNA) may co-exist as heteroplasmy and cause human disease. The purpose of the protocols in this article is to simultaneously determine the mtDNA sequence and quantify the heteroplasmy level using parallel sequencing. The protocols include mitochondrial genomic DNA PCR amplification of two full-length products using two distinct sets of PCR primers. The PCR products are mixed at an equimolar ratio, and the samples are then barcoded and sequenced with high-throughput next-generation sequencing technology. This technology is highly sensitive, specific, and accurate in determining mtDNA mutations and the degree/level of heteroplasmy. © 2022 Wiley Periodicals LLC. Basic Protocol 1: PCR amplification of mitochondrial DNA Basic Protocol 2: Analysis of next-generation sequencing of mitochondrial DNA Basic Protocol 3: Mutect2 pipeline for automated sample processing and large-scale data analysis.

Molecular mechanisms of coronary microvascular endothelial dysfunction in diabetes mellitus: focus on mitochondrial quality surveillance

Coronary microvascular endothelial dysfunction is both a culprit and a victim of diabetes, and can accelerate diabetes-related microvascular and macrovascular complications by promoting vasoconstrictive, pro-inflammatory and pro-thrombotic responses. Perturbed mitochondrial function induces oxidative stress, disrupts metabolism and activates apoptosis in endothelial cells, thus exacerbating the progression of coronary microvascular complications in diabetes. The mitochondrial quality surveillance (MQS) system responds to stress by altering mitochondrial metabolism, dynamics (fission and fusion), mitophagy and biogenesis. Dysfunctional mitochondria are prone to fission, which generates two distinct types of mitochondria: one with a normal and the other with a depolarized mitochondrial membrane potential. Mitochondrial fusion and mitophagy can restore the membrane potential and homeostasis of defective mitochondrial fragments. Mitophagy-induced decreases in the mitochondrial population can be reversed by mitochondrial biogenesis. MQS abnormalities induce pathological mitochondrial fission, delayed mitophagy, impaired metabolism and defective biogenesis, thus promoting the accumulation of unhealthy mitochondria and the activation of mitochondria-dependent apoptosis. In this review, we examine the effects of MQS on mitochondrial fitness and explore the association of MQS disorders with coronary microvascular endothelial dysfunction in diabetes. We also discuss the potential to treat diabetes-related coronary microvascular endothelial dysfunction using novel MQS-altering drugs.

Circulating cell-free mitochondrial DNA in brain health and disease: A systematic review and meta-analysis

OBJECTIVES

Circulating cell-free mitochondrial DNA (ccf-mtDNA) are detectable fragments of mtDNA released from the cell as a result of mitochondrial dysfunction or apoptosis. The brain is one of the most energy demanding organs in the human body, and many neuropsychiatric and non-psychiatric neurological diseases have mitochondrial dysfunction associated with disease pathophysiology. Thus, we aimed to assess ccf-mtDNA as a potential biomarker for brain diseases.

METHODS

We conducted a systematic review and meta-analyses of studies that examined peripheral and/or cerebrospinal fluid (CSF) ccf-mtDNA relevant to neuropsychiatric conditions, which we define as disorders of affect, behaviour and mood, and non-psychiatric neurological diseases, which consist of neurological diseases not related to psychiatry including neurodegenerative diseases.

RESULTS

The results of the sensitivity analysis investigating the levels of peripheral ccf-mtDNA in neuropsychiatric studies showed no significant difference between cases and controls (Z = 1.57; p = 0.12), whereas the results of the sensitivity analysis investigating the levels of CSF ccf-mtDNA in non-psychiatric neurological diseases showed a decreasing trend in cases compared with controls (Z = 2.32; p = 0.02). Interestingly, the results indicate an overall mitochondrial stress associated mainly with non-psychiatric neurological diseases.

CONCLUSIONS

Our study supports the involvement of mitochondrial stress, here defined as ccf-mtDNA, in brain diseases and encourage further investigation of ccf-mtDNA among patients with brain diseases.

Licorice (Glycyrrhiza glabra) Extracts-Suitable Pharmacological Interventions for COVID-19? A Review

Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms.

Yoga versus massage in the treatment of aromatase inhibitor-associated knee joint pain in breast cancer survivors: a randomized controlled trial

Aromatase inhibitors (AIs) are standard adjuvant therapy for postmenopausal women with oestrogen receptor-positive, early-stage, and metastatic breast cancer. Although effective, the risk of falls due to AI-associated knee joint pain significantly increased. The aim of this study was to evaluate the therapeutic effects of yoga and massage on AI-associated knee joint pain. Breast cancer survivors were randomly assigned to a 6-week yoga intervention-2-week rest-6-week massage exposure (Yoga first, n = 30) or a 6-week massage intervention-2-week rest-6-week yoga exposure (Massage first, n = 30). Evaluations of the treatment efficacy were made at baseline, post-intervention, and post-exposure using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale, plasma cytokine levels, and changes in meridian energy. The results showed that yoga, superior to massage intervention, significantly reduced AI-associated knee joint pain, as demonstrated by the WOMAC pain score. The yoga intervention improvements were also associated with changes in plasma cytokine levels and meridian energy changes. In conclusion, this study provides scientific evidence that yoga was more effective than massage for reducing AI-associated knee joint pain. Meridian energy changes may provide another scientific, objective, non-invasive way to monitor the therapeutic effects of yoga and investigate another alternative, complementary medicine.

Hydroxysafflor yellow A alleviates cerebral ischemia reperfusion injury by suppressing apoptosis via mitochondrial permeability transition pore

BACKGROUND

Mitochondria are key cellular organelles that are essential for cell fate decisions. Hydroxysafflor yellow A (HSYA) has displayed an impressively essential role in protection of cerebral ischemia/reperfusion (I/R). However, the mitochondrial effect of HSYA on Brain Microvascular Endothelial Cells (BMECs) under I/R remains to be largely unclear.

PURPOSE

To evaluate the protective effects of HSYA-mediated mitochondrial permeability transition pore (mPTP) on cerebral I/R injury and its mechanism.

METHODS

Cerebral I/R injury was established by the model of Middle cerebral artery occlusion (MCAO) in rats. Furthermore, to further clarify the relevant mechanism of HSYA's effects on mPTP, inhibition of extracellular regulated protein kinases (ERK) with U0126 and transfect with Cyclophilin D (CypD) SiRNA to reversely verified whether the protective effects of HSYA were exerted by regulating the Mitogen-activated protein kinase kinase (MEK)/ERK/CypD pathway.

RESULTS

HSYA treatment significantly increased BMECs viability, decreased the generation of ROS, opening of mPTP and translocation of cytochrome c after OGD/R. In addition to inhibited CypD, HSYA potentiated MEK and increased phosphorylation of ERK expression in BMECs, inhibited apoptosis mediated by mitochondrial. Notably, HSYA also significantly ameliorated neurological deficits and decreased the infarct volume in rats.

CONCLUSION

HSYA reduced the CytC export from mitochondrial by inhibited the open of mPTP via MEK/ERK/CypD pathway, contributing to the protection of I/R. Thus, our study not only revealed novel mechanisms of HSYA for its anti-I/R function, but also provided a template for the design of novel mPTP inhibitor for the treatment of various mPTP-related diseases.

Mitochondrial Function as a Potential Tool for Assessing Function, Quality and Adulteration in Medicinal Herbal Teas

Quality control has been a significant issue in herbal medicine since herbs became widely used to heal. Modern technologies have improved the methods of evaluating the quality of medicinal herbs but the methods of adulterating them have also grown in sophistication. In this paper we undertook a comprehensive literature search to identify the key analytical techniques used in the quality control of herbal medicine, reviewing their uses and limitations. We also present a new tool, based on mitochondrial profiling, that can be used to measure medicinal herbal quality. Besides being fundamental to the energy metabolism required for most cellular activities, mitochondria play a direct role in cellular signalling, apoptosis, stress responses, inflammation, cancer, ageing, and neurological function, mirroring some of the most common reasons people take herbal medicines. A fingerprint of the specific mitochondrial effects of medicinal herbs can be documented in order to assess their potential efficacy, detect adulterations that modulate these effects and determine the relative potency of batches. Furthermore, through this method it will be possible to assess whole herbs or complex formulas thus avoiding the issues inherent in identifying active ingredients which may be complex or unknown. Thus, while current analytical methods focus on determining the chemical quality of herbal medicines, including adulteration and contamination, mitochondrial functional analysis offers a new way of determining the quality of plant derived products that is more closely linked to the biological activity of a product and its potential clinical effectiveness.

Polycystic Ovarian Syndrome and Fertility

Polycystic ovary syndrome (PCOS) is a common endocrinopathy that has been associated with impaired fertility. This chapter reviews the underlying pathophysiology of PCOS and the associated fertility barriers of the condition. Psychologic concerns, hypothalamic-pituitary, ovarian, and mitochondria dysfunction, obesity, and the role of vitamin D in PCOS are considered with respect to fertility. Lastly, pregnancy risk factors associated with PCOS are also reviewed.

Exploring the Biochemical Basis of the Meridian Tropism Theory for the Qi-Invigorating Traditional Chinese Medicine Herb Panax ginseng

We examined the effect of the Qi-invigorating Traditional Chinese Medicines (TCM) herb Panax ginseng (P.G.) on mitochondrial functions and cellular antioxidant capacity in different organs of mice. We found that the P.G. extracts had a significant effect on tissues of mice, with the generation of total adenylate pool (TAP) enhanced in all visceral tissues, but not for the brain. The mitochondrial membrane potential (MMP) and antioxidant capacity reflected by superoxide dismutase (SOD) and glutathione (GSH) increased only for the meridian tissues that P.G. belongs to including Heart, Spleen and Lung. Reactive oxygen species (ROS), as a combined result of the increased energy metabolism and antioxidant capacity, varied in different organs. We concluded that: 1) the Qi-invigorating TCM herb P.G. had a significant effect on mice by enhancing TAP production in all of the visceral tissues examined, except for the brain; 2) for the meridional tissues of P.G. (Heart, Spleen and Lung), the P.G. extracts not only promoted the TAP production, but also boosted the antioxidant capacity demonstrated by the simultaneous increase in TAP, and SOD and GSH.

The role and mechanism of mitochondrial functions and energy metabolism in the function regulation of the mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells that show self-renewal, multi-directional differentiation, and paracrine and immune regulation. As a result of these properties, the MSCs have great clinical application prospects, especially in the regeneration of injured tissues, functional reconstruction, and cell therapy. However, the transplanted MSCs are prone to ageing and apoptosis and have a difficult to control direction differentiation. Therefore, it is necessary to effectively regulate the functions of the MSCs to promote their desired effects. In recent years, it has been found that mitochondria, the main organelles responsible for energy metabolism and adenosine triphosphate production in cells, play a key role in regulating different functions of the MSCs through various mechanisms. Thus, mitochondria could act as effective targets for regulating and promoting the functions of the MSCs. In this review, we discuss the research status and current understanding of the role and mechanism of mitochondrial energy metabolism, morphology, transfer modes, and dynamics on MSC functions.

Differential regulation of mitochondrial complex I and oxidative stress based on metastatic potential of colorectal cancer cells

Mitochondria serve a vital role in cellular homeostasis as they regulate cell proliferation and death pathways, which are attributed to mitochondrial bioenergetics, free radicals and metabolism. Alterations in mitochondrial functions have been reported in various diseases, including cancer. Colorectal cancer (CRC) is one of the most common metastatic cancer types with high mortality rates. Although mitochondrial oxidative stress has been associated with CRC, its specific mechanism and contribution to metastatic progression remain poorly understood. Therefore, the aims of the present study were to investigate the role of mitochondria in CRC cells with low and high metastatic potential and to evaluate the contribution of mitochondrial respiratory chain (RC) complexes in oncogenic signaling pathways. The present results demonstrated that cell lines with low metastatic potential were resistant to mitochondrial complex I (C-I)-mediated oxidative stress, and had C-I inhibition with impaired mitochondrial functions. These adaptations enabled cells to cope with higher oxidative stress. Conversely, cells with high metastatic potential demonstrated functional C-I with improved mitochondrial function due to coordinated upregulation of mitochondrial biogenesis and metabolic reprogramming. Pharmacological inhibition of C-I in high metastatic cells resulted in increased sensitivity to cell death and decreased metastatic signaling. The present findings identified the differential regulation of mitochondrial functions in CRC cells, based on CRC metastatic potential. Specifically, it was suggested that a functional C-I is required for high metastatic features of cancer cells, and the role of C-I could be further examined as a potential target in the development of novel therapies for diagnosing high metastatic cancer types.

Central and Peripheral Metabolic Defects Contribute to the Pathogenesis of Alzheimer's Disease: Targeting Mitochondria for Diagnosis and Prevention

Significance: Epidemiological studies indicate that metabolic disorders are associated with an increased risk for Alzheimer's disease (AD). Metabolic remodeling occurs in the central nervous system (CNS) and periphery, even in the early stages of AD. Mitochondrial dysfunction has been widely accepted as a molecular mechanism underlying metabolic disorders. Therefore, focusing on early metabolic changes, especially from the perspective of mitochondria, could be of interest for early AD diagnosis and intervention. Recent Advances: We and others have identified that the levels of several metabolites are fluctuated in the periphery before their accumulation in the CNS, which plays an important role in the pathogenesis of AD. Mitochondrial remodeling is likely one of the earliest signs of AD, linking nutritional imbalance to cognitive deficits. Notably, by improving mitochondrial function, mitochondrial nutrients efficiently rescue cellular metabolic dysfunction in the CNS and periphery in individuals with AD. Critical Issues: Peripheral metabolic disorders should be intensively explored and evaluated for the early diagnosis of AD. The circulating metabolites derived from mitochondrial remodeling represent novel potential diagnostic biomarkers for AD that are more readily detected than CNS-oriented biomarkers. Moreover, mitochondrial nutrients provide a promising approach to preventing and delaying AD progression. Future Directions: Abnormal mitochondrial metabolism in the CNS and periphery is involved in AD pathogenesis. More clinical studies provide evidence for the suitability and reliability of circulating metabolites and cytokines for the early diagnosis of AD. Targeting mitochondria to rewire cellular metabolism is a promising approach to preventing AD and ameliorating AD-related metabolic disorders.

Insights Into the Role of Mitochondrial Ion Channels in Inflammatory Response

Mitochondria are the source of many pro-inflammatory signals that cause the activation of the immune system and generate inflammatory responses. They are also potential targets of pro-inflammatory mediators, thus triggering a severe inflammatory response cycle. As mitochondria are a central hub for immune system activation, their dysfunction leads to many inflammatory disorders. Thus, strategies aiming at regulating mitochondrial dysfunction can be utilized as a therapeutic tool to cure inflammatory disorders. Two key factors that determine the structural and functional integrity of mitochondria are mitochondrial ion channels and transporters. They are not only important for maintaining the ionic homeostasis of the cell, but also play a role in regulating reactive oxygen species generation, ATP production, calcium homeostasis and apoptosis, which are common pro-inflammatory signals. The significance of the mitochondrial ion channels in inflammatory response is still not clearly understood and will need further investigation. In this article, we review the different mechanisms by which mitochondria can generate the inflammatory response as well as highlight how mitochondrial ion channels modulate these mechanisms and impact the inflammatory processes.

Mitochondrial haplogroups and lifespan in a population isolate

Physiochemical differences between mitochondrial DNA (mtDNA) haplogroups that favor oxidative phosphorylation efficiency during periods of caloric limitation can lead to lifespan lengthening when food calories are less abundant. For example, prior work demonstrated that older female haplogroup H carriers had modestly lengthened lifespans beyond 60 years during the Great Depression, a time of caloric limitation in North America. The objective of the current study is to replicate the prior findings in an independent cohort that includes both sexes and younger ages. By determining and cross-referencing the mtDNA genotypes of a culturally homogeneous population isolate to the lifespans of their ancestors, we found that between 1930 and 1939, haplogroup H compared to haplogroup U carriers had a modestly lengthened lifespan (3 years) past 60 years (hazard ratio 2.35; CI₉₅ 1.41-3.90; p-value: 0.0029). The lifespan-lengthening association was apparent in both sexes but only after the age of 60. Our results provide further support for the role of mitochondrial genetics in lengthening human lifespan.

The spatio-temporal features of chicken mitochondrial ND2 gene heteroplasmy and the effects of nutrition factors on this gene

Mitochondrial heterogeneity is the presence of two or more types of mitochondrial (mt)DNA in the same individual/tissue/cell. It is closely related to animal health and disease. ND2 is a protein-coding gene in mtDNA, which participates in mitochondrial respiratory chain and oxidative phosphorylation. In previous studies, we observed that the mt.A5703T and mt.T5727G sites in the ND2 gene were the heteroplasmic variation sites. We used pyrophosphate sequencing technology to examine chicken mt.A5703T and mt.T5727G heteroplasmic sites in the ND2 gene, in different tissues and at different development stages in chickens. We also investigated whether nutritional factors could affect the mt.A5703T and mt.T5727G heteroplasmy. Our results showed that chicken mt.A5703T and mt.T5727G heteroplasmy had clear spatio-temporal specificities, which varied between tissues/development stages. The mtDNA heterogeneity was relatively stable upon nutrition intervention, 30% dietary energy restriction (from 18 to 48 days old) and different types of dietary fats (at 5% concentration, from 1 to 42 days old) did not change the breast muscle heteroplasmy of broilers at the mt.A5703T and mt.T5727G sites. In addition, multiple potential heteroplasmic sites were detected by clone sequencing in the ND2 region, which potentially reflected abundant heteroplasmy in the chicken mitochondrial genome. These results provide an important reference for further research on heteroplasmy in chicken mitochondria.

Deregulated Mitochondrial DNA in Diseases

Mitochondria play various important roles in energy production, metabolism, and apoptosis. Mitochondrial dysfunction caused by alterations in mitochondrial DNA (mtDNA) can lead to the initiation and progression of cancers and other diseases. These alterations include mutations and copy number variations. Especially, the mutations in D-loop, MT-ND1, and MT-ND5 affect mitochondrial functions and are widely detected in various cancers. Meanwhile, several other mutations have been correlated with muscular and neuronal diseases, especially MT-TL1 is deeply related. These pieces of evidence indicated mtDNA alterations in diseases show potential as a novel therapeutic target. mtDNA repair enzymes are the target for delaying or stalling the mtDNA damage-induced cancer progression and metastasis. Moreover, some mutations reveal a prognosis ability of the drug resistance. Current efforts aim to develop mitochondrial transplantation technique as a direct cure for deregulated mitochondria-associated diseases. This review summarizes the implications of mitochondrial dysfunction in cancers and other pathologies; and discusses the relevance of mitochondria-targeted therapies, along with their contribution as potential biomarkers.

Electron transport chain biogenesis activated by a JNK-insulin-Myc relay primes mitochondrial inheritance in Drosophila

Oogenesis features an enormous increase in mitochondrial mass and mtDNA copy number, which are required to furnish mature eggs with an adequate supply of mitochondria and to curb the transmission of deleterious mtDNA variants. Quiescent in dividing germ cells, mtDNA replication initiates upon oocyte determination in the Drosophila ovary, which necessitates active mitochondrial respiration. However, the underlying mechanism for this dynamic regulation remains unclear. Here, we show that an feedforward insulin-Myc loop promotes mitochondrial respiration and biogenesis by boosting the expression of electron transport chain subunits and of factors essential for mtDNA replication and expression, and for the import of mitochondrial proteins. We further reveal that transient activation of JNK enhances the expression of the insulin receptor and initiates the insulin-Myc signaling loop. This signaling relay promotes mitochondrial biogenesis in the ovary, and thereby plays a role in limiting the transmission of deleterious mtDNA mutations. Our study demonstrates cellular mechanisms that couple mitochondrial biogenesis and inheritance with oocyte development.

Polycystic ovary syndrome and mitochondrial dysfunction

Polycystic ovary syndrome (PCOS) is a prevalent hormonal disorder of premenopausal women worldwide and is characterized by reproductive, endocrine, and metabolic abnormalities. The clinical manifestations of PCOS include oligomenorrhea or amenorrhea, hyperandrogenism, ovarian polycystic changes, and infertility. Women with PCOS are at an increased risk of suffering from type 2 diabetes; me\tabolic syndrome; cardiovascular events, such as hypertension, dyslipidemia; gynecological diseases, including infertility, endometrial dysplasia, endometrial cancer, and ovarian malignant tumors; pregnancy complications, such as premature birth, low birthweight, and eclampsia; and emotional and mental disorders in the future. Although numerous studies have focused on PCOS, the underlying pathophysiological mechanisms of this disease remain unclear. Mitochondria play a key role in energy production, and mitochondrial dysfunction at the cellular level can affect systemic metabolic balance. The recent wide acceptance of functional mitochondrial disorders as a correlated factor of numerous diseases has led to the presupposition that abnormal mitochondrial metabolic markers are associated with PCOS. Studies conducted in the past few years have confirmed that increased oxidative stress is associated with the progression and related complications of PCOS and have proven the relationship between other mitochondrial dysfunctions and PCOS. Thus, this review aims to summarize and discuss previous and recent findings concerning the relationship between mitochondrial dysfunction and PCOS.

Mitochondrial Dysfunctions: A Thread Sewing Together Alzheimer's Disease, Diabetes, and Obesity

Metabolic disorders are severe and chronic impairments of the health of many people and represent a challenge for the society as a whole that has to deal with an ever-increasing number of affected individuals. Among common metabolic disorders are Alzheimer's disease, obesity, and type 2 diabetes. These disorders do not have a univocal genetic cause but rather can result from the interaction of multiple genes, lifestyle, and environmental factors. Mitochondrial alterations have emerged as a feature common to all these disorders, underlining perhaps an impaired coordination between cellular needs and mitochondrial responses that could contribute to their development and/or progression.

Molecular alterations of mitochondrial D-loop in oral leukoplakia

BACKGROUND

Over the years, numerous studies proposed a crucial role of mutations of nuclear DNA in the carcinogenesis process. Of late, many researchers suppose that alterations of mitochondrial DNA should not be excepted from this analysis. Mutational analysis of mitochondrial DNA displayed that mitochondrial D-loop is assessed as a hotspot for molecular alterations in various types of malignant tumors encompassing oral squamous cell carcinoma. Squamous cell carcinoma is believed to emerge through precancerous stages, which might be merely morphologic aspects of cumulative genetic variations.

METHODS

In keeping with this model of molecular tumor progression, this study aimed to investigate the qualitative and quantitative alterations that might occur in mitochondrial D-loop in oral leukoplakia whether dysplastic or not by semiquantitation of a product of the polymerase chain reaction and sequence analyses of mitochondrial D-loop gene.

RESULTS

Statistically significant increases in the mean values of D-loop concentrations were observed across the dysplasia gradient of oral leukoplakia. Sequence analyses revealed the presence of point mutations in both dysplastic and nondysplastic oral leukoplakia but not in normal mucosa.

CONCLUSION

The results of this study suggested that quantitative and qualitative alterations in mitochondrial D-loop could be a promising molecular marker for early detection and progression of the malignancy.

MiR-1a-3p mitigates isoproterenol-induced heart failure by enhancing the expression of mitochondrial ND1 and COX1

MicroRNAs (miRNAs) have become potential targets for the treatment of heart failure (HF). It has been shown that miR-1 can reverse cardiac hypertrophy during the compensatory phase of HF development, but it is unknown whether miR-1 can still reverse cardiac dysfunction and improve cardiac remodeling after HF progresses to the decompensation stage. We established a mouse model of isoproterenol-induced HF and then injected miR-1a-3p agomir (agomir-1) into the tail vein. Echocardiography showed that the mice treated with agomir-1 had significantly increased ejection fraction and fractional shortening. These mice also showed a decrease in the N-terminal pro-B type natriuretic peptide (NT-proBNP) levels, but this remained higher than in controls. Cardiac hypertrophy, myocardial fibrosis, apoptosis, and glycogen deposition were reduced in mice treated with agomir-1. Furthermore, we found that supplementation of agomir-1 increased the expression of two mitochondrial DNA-encoded proteins, mitochondrially encoded NADH dehydrogenase 1 (ND1) and mitochondrially encoded cytochrome c oxidase I (COX1). In conclusion, our study found that miR-1a-3p alleviated the symptoms of ISO-induced HF in mice by enhancing mitochondrial ND1 and COX1. The results of this work may provide new therapeutic strategies for the treatment of HF patients.

PINK1 Inhibits Local Protein Synthesis to Limit Transmission of Deleterious Mitochondrial DNA Mutations

We have previously proposed that selective inheritance, the limited transmission of damaging mtDNA mutations from mother to offspring, is based on replication competition in Drosophila melanogaster. This model, which stems from our observation that wild-type mitochondria propagate much more vigorously in the fly ovary than mitochondria carrying fitness-impairing mutations, implies that germ cells recognize the fitness of individual mitochondria and selectively boost the propagation of healthy ones. Here, we demonstrate that the protein kinase PINK1 preferentially accumulates on mitochondria enriched for a deleterious mtDNA mutation. PINK1 phosphorylates Larp to inhibit protein synthesis on the mitochondrial outer membrane. Impaired local translation on defective mitochondria in turn limits the replication of their mtDNA and hence the transmission of deleterious mutations to the offspring. Our work confirms that selective inheritance occurs at the organelle level during Drosophila oogenesis and provides molecular entry points to test this model in other systems.

Gene annotation errors are common in the mammalian mitochondrial genomes database

Background

Although animal mitochondrial DNA sequences are known to evolve rapidly, their gene arrangements often remain unchanged over long periods of evolutionary time. Therefore, comparisons of mitochondrial genomes may result in significant insights into the evolution both of organisms and of genomes. Mammalian mitochondrial genomes recently published in the GenBank database of NCBI show numerous rearrangements in various regions of the genome, from which it may be inferred that the mammalian mitochondrial genome is more dynamic than expected. However, it is alternatively possible that these are errors of annotation and, if so, are misleading our interpretations. In order to verify these possible errors of annotation, we performed a comparative genomic analysis of mammalian mitochondrial genomes available in the NCBI database.

Results

Using a combination of bioinformatics methods to carefully examine the mitochondrial gene arrangements in 304 mammalian species, we determined that there are only two sets of gene arrangements, one that is shared by all of the marsupials and another that is shared by all of the monotremes and eutherians, with these two arrangements differing only by the positions of tRNA genes in the region commonly designated as “WANCY” for the genes it comprises. All of the 68 other cases of reported gene rearrangements are errors. We note that there are also numerous errors of impossibly short, incorrect gene annotations, cases where genomes that are reported as complete are actually missing portions of the sequence, and genes that are clearly present but were not annotated in these records.

Conclusions

We judge that the application of simple bioinformatic tools in the verification of gene annotation, particularly for organelle genomes, would be a very useful enhancement for the curation of genome sequences submitted to GenBank.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5447-1) contains supplementary material, which is available to authorized users.

Jian-Pi-Yi-Shen Formula ameliorates chronic kidney disease: involvement of mitochondrial quality control network

BACKGROUND

Jian-Pi-Yi-Shen Formula (JPYSF), a Chinese herbal decoction with the efficacies of 'fortify the spleen and tonify the kidney' and 'activate blood and resolve stasis', is effective for the treatment of chronic kidney disease in clinic. However, the underlying mechanism remains unclear. The aim of this study was to investigate the therapeutic effects and possible mechanisms of JPYSF on retarding chronic kidney disease progression in 5/6 nephrectomized (5/6 Nx) rats.

METHODS

Perindopril (4 mg/kg/d) and JPYSF (2.72 g/kg/d) were administrated by gavage to 5/6 Nx rats daily for 6 weeks. The therapeutic effects of JPYSF were evaluated by renal function, pathological injury, and fibrosis. The protein levels associated with mitochondrial quality control network were measured by Western blot and immunofluorescence analysis.

RESULTS

5/6 Nx rats showed obvious decline in renal function as evidenced by increased serum creatinine, blood urea nitrogen, and urinary protein excretion, and significant injury in kidney structure as evidenced by glomerular hypertrophy, tubular atrophy, and interstitial fibrosis. Administration of JPYSF for 6 weeks could improve renal function and ameliorate kidney structure injury in 5/6 Nx rats. Furthermore, the remnant kidneys of 5/6 Nx rats showed unbalanced mitochondrial quality control network manifested as decreased mitochondrial biogenesis, fusion, and mitophagy, and increased mitochondrial fission. Treatment of JPYSF could restore aforesaid aspects of mitochondrial quality control network.

CONCLUSIONS

These results indicate that JPYSF can notably ameliorate 5/6 Nx-induced chronic kidney disease, which may be related with modulation of mitochondrial quality control network.

The Mitochondrial Endonuclease M20 Participates in the Down-Regulation of Mitochondrial DNA in Pollen Cells

Maintaining the appropriate number of mitochondrial DNA (mtDNA) molecules is crucial for supporting mitochondrial metabolism and function in both plant and animal cells. For example, a substantial decrease in mtDNA levels occurs as a key part of pollen development. The molecular mechanisms regulating mtDNA copy number are largely unclear, particularly with regard to those that reduce mtDNA levels. Here, we identified and purified a 20-kD endonuclease, M20, from maize (Zea mays) pollen mitochondria. We found M20 to be an His-Asn-His/Asn (H-N-H/N) nuclease that degrades linear and circular DNA in the presence of Mg²⁺ or Mn²⁺ Arabidopsis (Arabidopsis thaliana) AtM20, which shared high sequence similarity with maize M20, localized to the mitochondria, had a similar H-N-H/N structure, and degraded both linear and circular DNA. AtM20 transcript levels increased during pollen development, in parallel with a rapid reduction in mtDNA. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 genome-editing techniques were used to generate knockout lines of AtM20 (atm20), which exhibited a significant delay in the reduction in mtDNA levels in pollen vegetative cells but normal mtDNA levels in somatic cells. The delayed reduction in pollen mtDNA levels was rescued by the transgenic expression of AtM20 in atm20 plants. This study thus uncovers an endonucleolytic DNase in plant mitochondria and its crucial role in reducing mtDNA levels, pointing to the complex mechanism regulating mtDNA levels in plants.

The traditional uses, phytochemistry, and pharmacology of Atractylodes macrocephala Koidz.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Atractylodes macrocephala Koidz. (called Baizhu in China) is a medicinal plant that has long been used as a tonic agent in various ethno-medical systems in East Asia, especially in China, for the treatment of gastrointestinal dysfunction, cancer, osteoporosis, obesity, and fetal irritability.

AIM OF THE REVIEW

This review aims to provide a systematic summary on the botany, traditional uses, phytochemistry, pharmacology, pharmacokinetics, and toxicology of A. macrocephala to explore the future therapeutic potential and scientific potential of this plant.

MATERIALS AND METHODS

A literature search was performed on A. macrocephala using scientific databases including Web of Science, Google Scholar, Baidu Scholar, Springer, PubMed, SciFinder, and ScienceDirect. Information was also collected from classic books of Chinese herbal medicine, Ph.D. and M.Sc. dissertations, unpublished materials, and local conference papers on toxicology. Plant taxonomy was confirmed to the database "The Plant List" (www.theplantlist.org).

RESULTS

More than 79 chemical compounds have been isolated from A. macrocephala, including sesquiterpenoids, triterpenoids, polyacetylenes, coumarins, phenylpropanoids, flavonoids and flavonoid glycosides, steroids, benzoquinones, and polysaccharides. Crude extracts and pure compounds of A. macrocephala are used to treat gastrointestinal hypofunction, cancer, arthritis, osteoporosis, splenic asthenia, abnormal fetal movement, Alzheimer disease, and obesity. These extracts have various pharmacological effects, including anti-tumor activity, anti-inflammatory activity, anti-aging activity, anti-oxidative activity, anti-osteoporotic activity, neuroprotective activity, and immunomodulatory activity, as well as improving gastrointestinal function and gonadal hormone regulation.

CONCLUSIONS

A. macrocephala is a valuable traditional Chinese medicinal herb with multiple pharmacological activities. Pharmacological investigations support the traditional use of A. macrocephala, and may validate the folk medicinal use of A. macrocephala to treat many chronic diseases. The available literature shows that much of the activity of A. macrocephala can be attributed to sesquiterpenoids, polysaccharides and polyacetylenes. However, there is a need to further understand the molecular mechanisms and the structure-function relationship of these constituents, as well as their potential synergistic and antagonistic effects. Further research on the comprehensive evaluation of medicinal quality, the understanding of multi-target network pharmacology of A. macrocephala, as well as its long-term in vivo toxicity and clinical efficacy is recommended.

The Root of Atractylodes macrocephala Koidzumi Prevents Obesity and Glucose Intolerance and Increases Energy Metabolism in Mice

Targeting energy expenditure offers a strategy for treating obesity more effectively and safely. In previous studies, we found that the root of Atractylodes macrocephala Koidzumi (Atractylodis Rhizoma Alba, ARA) increased energy metabolism in C2C12 cells. Here, we investigated the effects of ARA on obesity and glucose intolerance by examining energy metabolism in skeletal muscle and brown fat in high-fat diet (HFD) induced obese mice. ARA decreased body weight gain, hepatic lipid levels and serum total cholesterol levels, but did not modify food intake. Fasting serum glucose, serum insulin levels and glucose intolerance were all improved in ARA treated mice. Furthermore, ARA increased peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) expression, and the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle tissues, and also prevented skeletal muscle atrophy. In addition, the numbers of brown adipocytes and the expressions of PGC1α and uncoupling protein 1 (UCP1) were elevated in the brown adipose tissues of ARA treated mice. Our results show that ARA can prevent diet-induced obesity and glucose intolerance in C5BL/6 mice and suggests that the mechanism responsible is related to the promotion of energy metabolism in skeletal muscle and brown adipose tissues.

Proliferation Cycle Causes Age Dependent Mitochondrial Deficiencies and Contributes to the Aging of Stem Cells

In addition to chronological aging, stem cells are also subject to proliferative aging during the adult life span. However, the consequences of proliferative cycle and their contributions to stem cells aging have not been well investigated. Using Drosophila female germ line stem cells as a model, we found that the replication cycle leads to the age dependent decline of female fecundity, and is a major factor causing developmental abnormalities in the progeny of old females. The proliferative aging does not cause telomere shortening, but causes an accumulation of mitochondrial DNA (mtDNA) mutations or rearrangements at the control region. We propose that damaging mutations on mtDNA caused by accumulation of proliferation cycles in aged stem cells may disrupt mitochondrial respiration chain and impair mtDNA replication and represent a conserved mechanism underlying stem cell aging.

Polymorphisms in the TFAM and PGC1-α genes and their association with polycystic ovary syndrome among South Indian women

We investigated the link between polymorphisms in genes involved in mitochondrial biogenesis, mitochondrial transcription factor A (TFAM) and Peroxisome proliferator activated receptor gamma coactivator-1 alpha (PGC-1α) and further studied the role of these genes on the pathophysiology of polycystic ovary syndrome (PCOS). This case-control study was carried out in 118 PCOS cases and 110 controls. In the present study we genotyped three polymorphisms of PGC1-α gene (rs8192678-Gly482Ser, rs13131226 and rs2970856) and polymorphism of TFAM gene (rs1937-+35G/C) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. In addition, to better understand genetic contributions to the pathophysiology of PCOS, mtDNA copy number (MCN) was quantified using a qRT-PCR assay in the subjects. The results revealed that the distribution of genotypes and allele frequency of the PGC-1α Gly482Ser polymorphism in PCOS patients was statistically significant from those of the control group respectively (OR-2.488; 95% CI-1.0673 to 5.7998; P=0.047), (OR-1.6091; 95% CI-1.0955 to 2.3634; P=0.015) indicating that the presence of 'A' allele might confer risk to PCOS. Patients with the 'AA' genotype showed significantly lower levels of MCN compared with patients with other genotypes. In addition, patients carrying CT genotype of PGC1-α rs2970856 demonstrated significantly higher levels of LH (P=0.030) than TT and CC genotypes. In conclusion, our study indicates that carriers of the PGC-1α rs8192678 'Ser' allele have increased risk of developing PCOS.

Association of mitochondrial DNA in peripheral blood with depression, anxiety and stress- and adjustment disorders in primary health care patients

Mitochondrial dysfunction may result in a variety of diseases. The objectives here were to examine possible differences in mtDNA copy number between healthy controls and patients with depression, anxiety or stress- and adjustment disorders; the association between mtDNA copy number and disease severity at baseline; and the association between mtDNA copy number and response after an 8-week treatment (mindfulness, cognitive based therapy). A total of 179 patients in primary health care (age 20-64 years) with depression, anxiety and stress- and adjustment disorders, and 320 healthy controls (aged 19-70 years) were included in the study. Relative mtDNA copy number was measured using quantitative real-time PCR on peripheral blood samples. We found that the mean mtDNA copy number was significantly higher in patients compared to controls (84.9 vs 75.9, p<0.0001) at baseline. The difference in mtDNA copy number between patients and controls remained significant after controlling for age and sex (ß=8.13, p<0.0001; linear regression analysis). The mtDNA copy number was significantly associated with Patient Health Questionnaire (PHQ-9) scores (β=0.57, p=0.02) at baseline. After treatment, the change in mtDNA copy number was significantly associated with the treatment response, i.e., change in Hospital Anxiety and Depression Scale (HADS-D) and PHQ-9 scores (ß=1.00, p=0.03 and ß=0.65, p=0.04, respectively), after controlling for baseline scores, age, sex, BMI, smoking status, alcohol drinking and medication. Our findings show that mtDNA copy number is associated with symptoms of depression, anxiety and stress- and adjustment disorders and treatment response in these disorders.

No effect of mitochondrial genotype on reproductive plasticity following exposure to a non-infectious pathogen challenge in female or male Drosophila

Mitochondrial genetic variation shapes the expression of life-history traits associated with reproduction, development and survival, and has also been associated with the prevalence and progression of infectious bacteria and viruses in humans. The breadth of these effects on multifaceted components of health, and their link to disease susceptibility, led us to test whether variation across mitochondrial haplotypes affected reproductive success following an immune challenge in the form of a non-infectious pathogen. We test this, by challenging male and female fruit flies (Drosophila melanogaster), harbouring each of three distinct mitochondrial haplotypes in an otherwise standardized genetic background, to either a mix of heat-killed bacteria, or a procedural control, prior to measuring their subsequent reproductive performance. The effect of the pathogen challenge on reproductive success did not differ across mitochondrial haplotypes; thus there was no evidence that patterns of reproductive plasticity were modified by the mitochondrial genotype following a non-infectious pathogen exposure. We discuss the implications of our data, and suggest future research avenues based on these results.

Selection on the mitochondrial ATP synthase 6 and the NADH dehydrogenase 2 genes in hares (Lepus capensis L., 1758) from a steep ecological gradient in North Africa

Background

Recent studies of selection on mitochondrial (mt) OXPHOS genes suggest adaptation due mainly to environmental variation. In this context, Tunisian hares that display several external phenotypes with phylogenetically rather homogenous gene pool and shallow population structure provide a good precondition to detect positive selection on mt genes related to environmental/climatic variation, specifically ambient temperature and precipitation.

Results

We used codon-based methods along with population genetic data to test for positive selection on ATPase synthase 6 (ATP6) and NADH dehydrogenase 2 (ND2) of cape hares (Lepus capensis) collected along a steep ecological gradient in Tunisia. We found significantly higher differentiation at the ATP6 locus across Tunisia, with sub-humid Mediterranean, semi-arid, and arid Sahara climate than for fourteen unlinked supposedly neutrally evolving nuclear microsatellites and mt control region sequences. This suggested positive selection on ATP6 sequences, which was confirmed by several codon-based tests for one sequence site that together with a second site translated into four different amino acids. Positive selection on ND2 sequences was also confirmed by several codon-based tests. The corresponding frequencies of the two most prevalent variants at each locus varied significantly across climate regions, and our logistic general linear models of occurrence of those proteins indicated significant effects of mean annual temperature for ATP6 and mean minimum temperature of the coldest month of the year for ND2, independent of geographical location, annual precipitation, and the respective co-occurring protein at the second locus. Moreover, presence of the ancestral ATP6 protein, as inferred from phylogenetic networks, was positively affected by the simultaneous presence of the derived ND2 protein and vice versa, independent of temperature, precipitation, or geographic location. Finally, we obtained a significant coevolution signal for the ancestral ATP6 and derived ND2 sequences and vice versa.

Conclusions

positive selection was strongly suggested by the population genetic approach and the codon-based tests in both mtDNA genes. Moreover, the two most prevalent proteins at the ATP6 locus were distributed at significantly varying frequencies across the study area with a significant effect of mean annual temperature on the occurrence of the ATP6 proteins independent of geographical coordinates and the co-occuring ND2 protein variant. For ND2, occurrence of the two most frequent protein variants was significantly influenced by the mean minimum temperature of the coldest month, independent of the co-occurring ATP6 protein variant and geographical coordinates. This strongly suggests direct involvement of ambient temperature in the adaptation of the studied mtOXPHOS genes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0896-0) contains supplementary material, which is available to authorized users.

Characterization of Bombyx mori mitochondrial transcription factor A, a conserved regulator of mitochondrial DNA

In the present study, we initially cloned and characterized a mitochondrial transcription factor A (Tfam) homologue in the silkworm, Bombyx mori. Bombyx mori TFAM (BmTFAM) localized to mitochondria in cultured silkworm and human cells, and co-localized with mtDNA nucleoids in human HeLa cells. In an immunoprecipitation analysis, BmTFAM was found to associate with human mtDNA in mitochondria, indicating its feature as a non-specific DNA-binding protein. In spite of the low identity between BmTFAM and human TFAM (26.5%), the expression of BmTFAM rescued mtDNA copy number reductions and enlarged mtDNA nucleoids in HeLa cells, which were induced by human Tfam knockdown. Thus, BmTFAM compensates for the function of human TFAM in HeLa cells, demonstrating that the mitochondrial function of TFAM is highly conserved between silkworms and humans. BmTfam mRNA was strongly expressed in early embryos. Through double-stranded RNA (dsRNA)-based RNA interference (RNAi) in silkworm embryos, we found that the knockdown of BmTFAM reduced the amount of mtDNA and induced growth retardation at the larval stage. Collectively, these results demonstrate that BmTFAM is a highly conserved mtDNA regulator and may be a good candidate for investigating and modulating mtDNA metabolism in this model organism.

Changes in mitochondrial homeostasis and redox status in astronauts following long stays in space

The effects of long-term exposure to extreme space conditions on astronauts were investigated by analyzing hair samples from ten astronauts who had spent six months on the International Space Station (ISS). Two samples were collected before, during and after their stays in the ISS; hereafter, referred to as Preflight, Inflight and Postflight, respectively. The ratios of mitochondrial (mt) to nuclear (n) DNA and mtRNA to nRNA were analyzed via quantitative PCR. The combined data of Preflight, Inflight and Postflight show a significant reduction in the mtDNA/nDNA in Inflight, and significant reductions in the mtRNA/nRNA ratios in both the Inflight and Postflight samples. The mtRNA/mtDNA ratios were relatively constant, except in the Postflight samples. Using the same samples, the expression of redox and signal transduction related genes, MnSOD, CuZnSOD, Nrf2, Keap1, GPx4 and Catalase was also examined. The results of the combined data from Preflight, Inflight and Postflight show a significant decrease in the expression of all of the redox-related genes in the samples collected Postflight, with the exception of Catalase, which show no change. This decreased expression may contribute to increased oxidative stress Inflight resulting in the mitochondrial damage that is apparent Postflight.

Translational regulation of mitochondrial biogenesis

Mitochondria are generated by the expression of genes on both nuclear and mitochondrial genome. Mitochondrial biogenesis is highly plastic in response to cellular energy demand, developmental signals and environmental stimuli. Mechanistic target of rapamycin (mTOR) pathway regulates mitochondrial biogenesis to co-ordinate energy homeostasis with cell growth. The local translation of mitochondrial proteins on the outer membrane facilitates their efficient import and thereby allows prodigious mitochondrial biogenesis during rapid cell growth and proliferation. We postulate that the local translation may also allow cells to promote mitochondrial biogenesis selectively based on the fitness of individual organelle. MDI–Larp complex promotes the biogenesis of healthy mitochondria and thereby is essential for the selective transmission of healthy mitochondria. On the other hand, PTEN-induced putative kinase 1 (PINK1)–Pakin activates protein synthesis on damaged mitochondria to maintain the organelle homeostasis and activity. We also summarize some recent progress on miRNAs' regulation on mitochondrial biogenesis.

The rise of mitochondria in medicine

Once considered exclusively the cell's powerhouse, mitochondria are now recognized to perform multiple essential functions beyond energy production, impacting most areas of cell biology and medicine. Since the emergence of molecular biology and the discovery of pathogenic mitochondrial DNA defects in the 1980's, research advances have revealed a number of common human diseases which share an underlying pathogenesis involving mitochondrial dysfunction. Mitochondria undergo function-defining dynamic shape changes, communicate with each other, regulate gene expression within the nucleus, modulate synaptic transmission within the brain, release molecules that contribute to oncogenic transformation and trigger inflammatory responses systemically, and influence the regulation of complex physiological systems. Novel mitopathogenic mechanisms are thus being uncovered across a number of medical disciplines including genetics, oncology, neurology, immunology, and critical care medicine. Increasing knowledge of the bioenergetic aspects of human disease has provided new opportunities for diagnosis, therapy, prevention, and in connecting various domains of medicine. In this article, we overview specific aspects of mitochondrial biology that have contributed to - and likely will continue to enhance the progress of modern medicine.

The hepatoprotective effect of the combination use of Fructus Schisandrae with statin--A preclinical evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Schisandrae is traditionally used as a liver-toning Chinese herb. Recent studies suggested Fructus Schisandrae could prevent high-fat diet-induced hepatic steatosis as well as improving anti-oxidative status within the liver, which is a proposed mechanism against statin-induced liver toxicity.

AIM

The aim of the present study was to determine if the combination use of Atorvastatin (AS) and Fructus Schisandrae aqueous extract (FSE) could (a) exert potent therapeutic effects not only on high-fat diet-induced hyperlipidemia, but also on hepatomegaly (enlarge of liver size) and hepatic steatosis (fatty liver); and (b) reduce side effects caused by intake of statin alone including increased incidence of elevated liver enzymes and liver toxicity in Sprague Dawley rats.

MATERIALS AND METHODS

We studied 5 groups of Sprague Dawley rats that were given the following treatment for 8 weeks: (i) Normal-chow diet; (ii) High-fat diet (contains 21% fat and 0.15% cholesterol); (iii) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.3% Atorvastatin; (iv) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.45% FSE; (v) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.3% Atorvastatin+0.45% FSE. After 8 weeks of treatment, body weight, adipose tissue and liver mass were measured, and liver and plasma lipid levels were determined to evaluate to effect of FSE with or without AS treatment on diet-induced obesity, hyperlipidemia and hepatic steatosis. Liver enzyme activities, anti-oxidative status and membrane permeability transition were also assessed to determine if FSE could reduce the side effects induced by AS.

RESULTS

From the results, FSE treatment alone resulted in significant inhibitory effect on diet-induced increase in: (a) body weight; (b) fat pad mass (epididymal, perirenal and inguinal fat); (c) liver weight; (d) total liver lipid; (e) liver triglyceride and cholesterol levels; and (f) plasma lipid levels, suggesting FSE has a potential preventive beneficial effect on weight control and lipid metabolism in Sprague Dawley rats with diet-induced obesity. However, FSE supplementation exerted no further beneficial effect on diet-induced metabolic syndrome when it is combined with AS treatment, compared with rats given AS-treatment alone. At the dose of 0.45%, dietary FSE supplementation resulted in: (a) reduced liver enzymes (ALT and AST) levels; (b) reduced macrophage infiltration (CD68); (c) improved liver glutathione levels (anti-oxidative status); (d) reduced liver reactive oxidative species; (e) a trend to reduce calcium-induced membrane permeability transition within the liver. Most importantly, these improvements induced by FSE treatment were not only observed in the livers of rats given high-fat-diet, but also in high-fat-fed rats with atorvastatin-induced hepatotoxicity.

CONCLUSIONS

Taken together, these data suggested FSE has a potential beneficial effect on weight control and lipid metabolism in Sprague Dawley rats with diet-induced obesity, and the combination use of FSE with AS could significantly prevent liver toxicity and anti-oxidative status induced by AS alone.

Age-related decrease in mtDNA content as a consequence of mtDNA 4977 bp deletion

As one of the most frequent somatic mutations accumulated during aging in human mitochondrial DNA, the 4977 bp deletion has intrigued scientific interest in recent years. Although many studies have shown a significant increase in the amount of 4977 bp deletion, the findings with respect to an age-dependent escalate of ΔmtDNA4977 bp in blood are still disputatious. Therefore, we investigated the presence of common deletion and mtDNA deletion level in whole blood samples of 100 old individuals (60-90 years). We detected the accumulation of common deletion in 46 old individuals. Consequently, there was statistically significant difference between the aged and young individuals in mitochondrial content (p = 0.01) and deletion levels ranged from 2% to 17% of the total mtDNA (mean: 10% ± 0.02%). We conclude that common deletion has decreased the mtDNA content; however, it is not clearly detectable in the blood as one of the fast replicating tissues comparing with tissues with low mitotic activity.

Cardiovascular Disease, Mitochondria, and Traditional Chinese Medicine

Recent studies demonstrated that mitochondria play an important role in the cardiovascular system and mutations of mitochondrial DNA affect coronary artery disease, resulting in hypertension, atherosclerosis, and cardiomyopathy. Traditional Chinese medicine (TCM) has been used for thousands of years to treat cardiovascular disease, but it is not yet clear how TCM affects mitochondrial function. By reviewing the interactions between the cardiovascular system, mitochondrial DNA, and TCM, we show that cardiovascular disease is negatively affected by mutations in mitochondrial DNA and that TCM can be used to treat cardiovascular disease by regulating the structure and function of mitochondria via increases in mitochondrial electron transport and oxidative phosphorylation, modulation of mitochondrial-mediated apoptosis, and decreases in mitochondrial ROS. However further research is still required to identify the mechanism by which TCM affects CVD and modifies mitochondrial DNA.

An integrated mechanism of pediatric pseudotumor cerebri syndrome: evidence of bioenergetic and hormonal regulation of cerebrospinal fluid dynamics

Pseudotumor cerebri syndrome (PTCS) is defined by the presence of elevated intracranial pressure (ICP) in the setting of normal brain parenchyma and cerebrospinal fluid (CSF). Headache, vision changes, and papilledema are common presenting features. Up to 10% of appropriately treated patients may experience permanent visual loss. The mechanism(s) underlying PTCS is unknown. PTCS occurs in association with a variety of conditions, including kidney disease, obesity, and adrenal insufficiency, suggesting endocrine and/or metabolic derangements may occur. Recent studies suggest that fluid and electrolyte balance in renal epithelia is regulated by a complex interaction of metabolic and hormonal factors; these cells share many of the same features as the choroid plexus cells in the central nervous system (CNS) responsible for regulation of CSF dynamics. Thus, we posit that similar factors may influence CSF dynamics in both types of fluid-sensitive tissues. Specifically, we hypothesize that, in patients with PTCS, mitochondrial metabolites (glutamate, succinate) and steroid hormones (cortisol, aldosterone) regulate CSF production and/or absorption. In this integrated mechanism review, we consider the clinical and molecular evidence for each metabolite and hormone in turn. We illustrate how related intracellular signaling cascades may converge in the choroid plexus, drawing on evidence from functionally similar tissues.