Novel mutations in ATPase 8, ND1 and ND5 genes associated with peripheral neuropathy of diabetes

Analysis of MT-ATP8 gene variants reported in patients by modeling in silico and in yeast model organism

Defects in ATP synthase functioning due to the substitutions in its two mitochondrially encoded subunits a and 8 lead to untreatable mitochondrial diseases. Defining the character of variants in genes encoding these subunits is challenging due to their low frequency, heteroplasmy of mitochondrial DNA in patients' cells and polymorphisms of mitochondrial genome. We successfully used yeast S. cerevisiae as a model to study the effects of variants in MT-ATP6 gene and our research led to understand how eight amino acid residues substitutions impact the proton translocation through the channel formed by subunit a and c-ring of ATP synthase at the molecular level. Here we applied this approach to study the effects of the m.8403T>C variant in MT-ATP8 gene. The biochemical data from yeast mitochondria indicate that equivalent mutation is not detrimental for the yeast enzyme functioning. The structural analysis of substitutions in subunit 8 introduced by m.8403T>C and five other variants in MT-ATP8 provides indications about the role of subunit 8 in the membrane domain of ATP synthase and potential structural consequences of substitutions in this subunit.

Mitochondrial DNA abnormalities and metabolic syndrome

Metabolic syndrome (MetS) is a complex pathological condition that involves disrupted carbohydrate, protein, and fat metabolism in the human body, and is a major risk factor for several chronic diseases, including diabetes, cardiovascular disease, and cerebrovascular disease. While the exact pathogenesis of metabolic syndrome is not yet fully understood, there is increasing evidence linking mitochondrial dysfunction, which is closely related to the mitochondrial genome and mitochondrial dynamics, to the development of this condition. Recent advancements in genetic sequencing technologies have allowed for more accurate detection of mtDNA mutations and other mitochondrial abnormalities, leading to earlier diagnosis and intervention in patients with metabolic syndrome. Additionally, the identification of specific mechanisms by which reduced mtDNA copy number and gene mutations, as well as abnormalities in mtDNA-encoded proteins and mitochondrial dynamics, contribute to metabolic syndrome may promote the development of novel therapeutic targets and interventions, such as the restoration of mitochondrial function through the targeting of specific mitochondrial defects. Additionally, advancements in genetic sequencing technologies may allow for more accurate detection of mtDNA mutations and other mitochondrial abnormalities, leading to earlier diagnosis and intervention in patients with MetS. Therefore, strategies to promote the restoration of mitochondrial function by addressing these defects may offer new options for treating MetS. This review provides an overview of the research progress and significance of mitochondrial genome and mitochondrial dynamics in MetS.

Identification of Type 2 Diabetes Biomarkers From Mixed Single-Cell Sequencing Data With Feature Selection Methods

Diabetes is the most common disease and a major threat to human health. Type 2 diabetes (T2D) makes up about 90% of all cases. With the development of high-throughput sequencing technologies, more and more fundamental pathogenesis of T2D at genetic and transcriptomic levels has been revealed. The recent single-cell sequencing can further reveal the cellular heterogenicity of complex diseases in an unprecedented way. With the expectation on the molecular essence of T2D across multiple cell types, we investigated the expression profiling of more than 1,600 single cells (949 cells from T2D patients and 651 cells from normal controls) and identified the differential expression profiling and characteristics at the transcriptomics level that can distinguish such two groups of cells at the single-cell level. The expression profile was analyzed by several machine learning algorithms, including Monte Carlo feature selection, support vector machine, and repeated incremental pruning to produce error reduction (RIPPER). On one hand, some T2D-associated genes (MTND4P24, MTND2P28, and LOC100128906) were discovered. On the other hand, we revealed novel potential pathogenic mechanisms in a rule manner. They are induced by newly recognized genes and neglected by traditional bulk sequencing techniques. Particularly, the newly identified T2D genes were shown to follow specific quantitative rules with diabetes prediction potentials, and such rules further indicated several potential functional crosstalks involved in T2D.

Mitochondrial ATP6 and ND3 genes are associated with type 2 diabetic peripheral neuropathy

BACKGROUND AND AIMS

The association of mitochondrial NADH dehydrogenase gene mutations with type 2 diabetes in the Karaikudi population was previously reported. This is a case report that demonstrated rare mutations are responsible for maternally inherited peripheral neuropathy of diabetes.

METHODS

We describe a 70-year-old male and his family (n = 25) with type 2 diabetic peripheral neuropathy having four rare mutations, 8597T > C, 8699T > C, 8966T > C, 10188A > G, and 9 bp deletion in various regions of the mitochondrial genes. Mutations were identified through direct sequencing of DNA isolated from the blood of the selected individuals. Blood samples were also analyzed for glucose, hemoglobin A1c, triglyceride, total cholesterol, oxidative stress markers, antioxidant status, cytochrome-C-oxidase and mitochondrial DNA content using appropriate methods.

RESULTS

Oxidative stress markers were found elevated while the antioxidant status, mitochondrial DNA content and the activity of cytochrome C-oxidase was reduced significantly. Analysis of mtDNA showed the presence of several mutations in various regions of mitochondrial genome. However, 8597T > C, 8699T > C, 8966T > C, 10188A > G, and 9 bp deletion were observed in the patient's family including his siblings.

CONCLUSION

This study shows that the mutations observed in the patient and his family is maternally inherited and suspected to be pathogenic in developing T2D associated peripheral neuropathy.

The Mitochondrial Complex(I)ty of Cancer

Recent evidence highlights that the cancer cell energy requirements vary greatly from normal cells and that cancer cells exhibit different metabolic phenotypes with variable participation of both glycolysis and oxidative phosphorylation. NADH-ubiquinone oxidoreductase (Complex I) is the largest complex of the mitochondrial electron transport chain and contributes about 40% of the proton motive force required for mitochondrial ATP synthesis. In addition, Complex I plays an essential role in biosynthesis and redox control during proliferation, resistance to cell death, and metastasis of cancer cells. Although knowledge about the structure and assembly of Complex I is increasing, information about the role of Complex I subunits in tumorigenesis is scarce and contradictory. Several small molecule inhibitors of Complex I have been described as selective anticancer agents; however, pharmacologic and genetic interventions on Complex I have also shown pro-tumorigenic actions, involving different cellular signaling. Here, we discuss the role of Complex I in tumorigenesis, focusing on the specific participation of Complex I subunits in proliferation and metastasis of cancer cells.

Mitochondrial complex I and V gene polymorphisms in type II diabetes mellitus among high risk Mizo-Mongoloid population, Northeast India

Introduction

The study was carried out to identify the polymorphisms in mitochondrial genes (ATPase and ND1) in type 2 Diabetes Mellitus (T2DM) from Mizo population and to correlate the involvement of demographic factors.

Findings

In the present study, 58 patients and 50 healthy volunteers were considered. The mutations observed were mostly base substitutions and were similar as reported for other populations. Three mutations are unreported and were found to be novel polymorphisms for diabetic disease. One heteroplasmic variation (MT3970 C > T) was found in 36.36 % of samples. Subjects with excessive smoked meat consumption and customary habit of smoking (ORs: 4.92; 95 % CI: 0.96–25.21) were found to be more prone to T2DM. Mitochondrial genes sequence analysis revealed the genetic variability between the healthy and diabetic samples.

Conclusion

Mitochondrial ATPase and ND1 gene polymorphisms may be involved in triggering the risk for T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s41021-016-0034-z) contains supplementary material, which is available to authorized users.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicated in the diabetic neuropathies and to highlight potential commonalities. We thereby aim to contribute to the creation of a genetic-metabolic model that will help to elucidate the cause of diabetic neuropathies, evaluate a patient's risk profile, and ultimately facilitate preventative and targeted treatment for the individual.