Review of current status of molecular diagnosis and characterization of monogenic diabetes mellitus: a focus on next-generation sequencing

Next Generation Sequencing (NGS) Target Approach for Undiagnosed Dysglycaemia

Next-generation sequencing (NGS) has revolutionized the field of genomics and created new opportunities for basic research. We described the strategy for the NGS validation of the "dysglycaemia panel" composed by 44 genes related to glucose metabolism disorders (MODY, Wolfram syndrome) and familial renal glycosuria using Ion AmpliSeq technology combined with Ion-PGM. Anonymized DNA of 32 previously genotyped cases with 33 different variants were used to optimize the methodology. Standard protocol was used to generate the primer design, library, template preparation, and sequencing. Ion Reporter tool was used for data analysis. In all the runs, the mean coverage was over 200×. Twenty-nine out of thirty three variants (96.5%) were detected; four frameshift variants were missed. All point mutations were detected with high sensitivity. We identified three further variants of unknown significance in addition to pathogenic mutations previously identified by Sanger sequencing. The NGS panel allowed us to identify pathogenic variants in multiple genes in a short time. This could help to identify several defects in children and young adults that have to receive the genetic diagnosis necessary for optimal treatment. In order not to lose any pathogenic variants, Sanger sequencing is included in our analytical protocol to avoid missing frameshift variants.

Biomarkers: Tools for Discriminating MODY from Other Diabetic Subtypes

Maturity Onset Diabetes of Young (MODY), characterized by the pancreatic b-cell dysfunction, the autosomal dominant mode of inheritance and early age of onset (often ≤25 years). It differs from normal type 1 and type 2 diabetes in that it occurs at a low rate of 1-5%, three-generational autosomal dominant patterns of inheritance and lacks typical diabetic features such as obesity. MODY patients can be managed by diet alone for many years, and sulfonylureas are also recommended to be very effective for managing glucose levels for more than 30 years. Despite rapid advancements in molecular disease diagnosis methods, MODY cases are frequently misdiagnosed as type 1 or type 2 due to overlapping clinical features, genetic testing expenses, and a lack of disease understanding. A timely and accurate diagnosis method is critical for disease management and its complications. An early diagnosis and differentiation of MODY at the clinical level could reduce the risk of inappropriate insulin or sulfonylurea treatment therapy and its associated side effects. We present a broader review to highlight the role and efficacy of biomarkers in MODY differentiation and patient selection for genetic testing analysis.

UBE2D1 and COX7C as Potential Biomarkers of Diabetes-Related Sepsis

Patients with diabetes are physiologically frail and more likely to suffer from infections and even life-threatening sepsis. This study aimed to identify and verify potential biomarkers of diabetes-related sepsis (DRS). Datasets GSE7014, GSE57065, and GSE95233 from the Gene Expression Omnibus were used to explore diabetes- and sepsis-related differentially expressed genes (DEGs). Gene set enrichment analysis (GSEA) and functional analyses were performed to explore potential functions and pathways associated with sepsis and diabetes. Weighted gene co-expression network analysis (WGCNA) was performed to identify diabetes- and sepsis-related modules. Functional enrichment analysis was performed to determine the characteristics and pathways of key modules. Intersecting DEGs that were also present in key modules were considered as common DEGs. Protein-protein interaction (PPI) network and key genes were analyzed to screen hub genes involved in DRS development. A mouse C57 BL/6J-DRS model and a neural network prediction model were constructed to verify the relationship between hub genes and DRS. In total, 7457 diabetes-related DEGs and 2606 sepsis-related DEGs were identified. GSEA indicated that gene datasets associated with diabetes and sepsis were mainly enriched in metabolic processes linked to inflammatory responses and reactive oxygen species, respectively. WGCNA indicated that grey60 and brown modules were diabetes- and sepsis-related key modules, respectively. Functional analysis showed that grey60 module genes were mainly enriched in cell morphogenesis, heart development, and the PI3K-Akt signaling pathway, whereas genes from the brown module were mainly enriched in organelle inner membrane, mitochondrion organization, and oxidative phosphorylation. UBE2D1, IDH1, DLD, ATP5C1, COX6C, and COX7C were identified as hub genes in the PPI network. Animal DRS and neural network prediction models indicated that the expression levels of UBE2D1 and COX7C in DRS models and samples were higher than control mice. UBE2D1 and COX7C were identified as potential biomarkers of DRS. These findings may help develop treatment strategies for DRS.

Which BMI for Diabetes Patients is Better? From the View of the Adipose Tissue Macrophage-Derived Exosome

PURPOSE

Diabetes, as a group of metabolic diseases, can elevate blood glucose, thus leading to the development of life-threatening complications. It is difficult to define the outcome for diabetics with different BMI. This review will illustrate the adipose tissue macrophage-derived exosome in the diabetics with different BMI.

PATIENTS AND METHODS

Insulin resistance in peripheral tissues can cause diabetes. The peripheral tissues include liver, muscle, or the adipose depots. Communication between these organs is fatal to the maintenance of glucose homeostasis. This review will illustrate this communication. Obesity is closely linked with diabetes. There are different changes in fat distribution in diabetic patients. Adipose tissue macrophages can secrete various hormones, including adiponectin, leptin, resistin and other classical cytokines, such as TNF-α and IL-6. Studies illustrated that exosomes from the adipose tissue, can modulate inter-organ cross-talk by regulating gene expression in other tissues.

RESULTS

Adipose tissue macrophages exosomes links thin and fat individuals in the development of diabetes.

CONCLUSION

The molecular pathways initiated by exosomes such as miRNA in the situations of metabolic stress could help us gain a deeper knowledge of the pathophysiology of diabetes.

Stem Cell Transplantation in the Treatment of Type 1 Diabetes Mellitus: From Insulin Replacement to Beta-Cell Replacement

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that attacks pancreatic β-cells, leading to the destruction of insulitis-related islet β-cells. Islet β-cell transplantation has been proven as a curative measure in T1DM. However, a logarithmic increase in the global population with diabetes, limited donor supply, and the need for lifelong immunosuppression restrict the widespread use of β-cell transplantation. Numerous therapeutic approaches have been taken to search for substitutes of β-cells, among which stem cell transplantation is one of the most promising alternatives. Stem cells have demonstrated the potential efficacy to treat T1DM by reconstitution of immunotolerance and preservation of islet β-cell function in recent research. cGMP-grade stem cell products have been used in human clinical trials, showing that stem cell transplantation has beneficial effects on T1DM, with no obvious adverse reactions. To better achieve remission of T1DM by stem cell transplantation, in this work, we explain the progression of stem cell transplantation such as mesenchymal stem cells (MSCs), human embryonic stem cells (hESCs), and bone marrow hematopoietic stem cells (BM-HSCs) to restore the immunotolerance and preserve the islet β-cell function of T1DM in recent years. This review article provides evidence of the clinical applications of stem cell therapy in the treatment of T1DM.

The Application of Next Generation Sequencing Maturity Onset Diabetes of the Young Gene Panel in Turkish Patients from Trakya Region

OBJECTIVE

The aim of this study was to investigate the molecular basis of maturity-onset diabetes of the young (MODY) by targeted-gene sequencing of 20 genes related to monogenic diabetes, estimate the frequency and describe the clinical characteristics of monogenic diabetes and MODY in the Trakya Region of Turkey.

METHODS

A panel of 20 monogenic diabetes related genes were screened in 61 cases. Illumina NextSeq550 system was used for sequencing. Pathogenicity of the variants were assessed by bioinformatics prediction software programs and segregation analyses.

RESULTS

In 29 (47.5%) cases, 31 pathogenic/likely pathogenic variants in the GCK, ABCC8, KCNJ11, HNF1A, HNF4A genes and in 11 (18%) cases, 14 variants of uncertain significance (VUS) in the GCK, RFX6, CEL, PDX1, KCNJ11, HNF1A, G6PC2, GLIS3 and KLF11 genes were identified. There were six different pathogenic/likely pathogenic variants and six different VUS which were novel.

CONCLUSION

This is the first study including molecular studies of twenty monogenic diabetes genes in Turkish cases in the Trakya Region. The results showed that pathogenic variants in the GCK gene are the leading cause of MODY in our population. A high frequency of novel variants (32.4%-12/37) in the current study, suggests that multiple gene analysis provides accurate genetic diagnosis in MODY.

A Comprehensive Analysis of Hungarian MODY Patients-Part I: Gene Panel Sequencing Reveals Pathogenic Mutations in HNF1A, HNF1B, HNF4A, ABCC8 and INS Genes

Maturity-onset diabetes of the young (MODY) has about a dozen known causal genes to date, the most common ones being HNF1A, HNF4A, HNF1B and GCK. The phenotype of this clinically and genetically heterogeneous form of diabetes depends on the gene in which the patient has the mutation. We have tested 450 Hungarian index patients with suspected MODY diagnosis with Sanger sequencing and next-generation sequencing and found a roughly 30% positivity rate. More than 70% of disease-causing mutations were found in the GCK gene, about 20% in the HNF1A gene and less than 10% in other MODY-causing genes. We found 8 pathogenic and 9 likely pathogenic mutations in the HNF1A gene in a total of 48 patients and family members. In the case of HNF1A-MODY, the recommended first-line treatment is low dose sulfonylurea but according to our data, the majority of our patients had been on unnecessary insulin therapy at the time of requesting their genetic testing. Our data highlights the importance of genetic testing in the diagnosis of MODY and the establishment of the MODY subtype in order to choose the most appropriate treatment.

Icariin Protects Mouse Insulinoma Min6 Cell Function by Activating the PI3K/AKT Pathway

Background

Type 2 diabetes (T2D) is characterized by β-cell dysfunction and insulin resistance. Icariin (ICA), a flavonoid from Epimedium, possesses anti-diabetic and anti-inflammatory properties. However, it is unclear whether ICA acts on pancreatic β-cells. The present study was designed to explore the effects and latent mechanism of ICA on uric acid (UA)-stimulated pancreatic β-cell dysfunction.

Material/Methods

Min6 cells were exposed to various concentrations of ICA for 24 h, and cell viability was assessed by MTT assays. Min6 cells were treated with ICA for 2 h, followed by 5 mg/dl UA for 24 h, and cell viability, apoptosis, apoptosis-associated protein levels and insulin secretion were assessed by MTT, flow cytometry, western blotting and glucose-stimulated insulin secretion assays, respectively. The effects of ICA and UA on the PI3K/Akt pathway were also analyzed by western blotting, as were the effects of the specific PI3K/Akt inhibitor LY294002.

Results

ICA was not cytotoxic toward Min6 cells. UA decreased Min6 cell viability, enhanced cell apoptosis and levels of cleaved caspase-3, and reduced pro-caspase3 levels and insulin secretion, with all of these effects reversed by ICA in a dose-dependent manner. UA inhibited the PI3K/AKT pathway, an effect reversed by ICA treatment. The specific PI3K/Akt inhibitor LY294002, however, reversed these effects of ICA on UA-treated Min6 cells.

Conclusions

ICA protected Min6 cell function, an effect likely mediated by the PI3K pathway. ICA may inhibit the progression of diabetes.

Targeting the gut microbiota by Asian and Western dietary constituents: a new avenue for diabetes

Increasing numerous diabetes annually is a great concern in public health globally. Gut microbiota recently has been suggested to be an emerging organ acting as a critical regulator in diabetes. Notably, gut microbiota is closely affected through an individual's nutrient intake and dietary pattern. Moreover, the metabolites of diets through gut microbiota are closely associated with the development of diabetes. Increasing evidence has established the association of different dietary pattern with alterations of the gut microbiota profile, in particular, the Asian diet and Western diet are typically as essential components linked to the interactions between gut microbiota and induction of obesity which is a significant risk factor for diabetes. In addition, some bacteria-related therapeutic methods including probiotics, dietary short-chain fatty acids immunotherapy, and gut microbiome transfer would be applied in the clinical prevention and control diabetes. Taken together, based on current published observations, the gut microbiota may serve as regulator or targets by the Asian diet and Western diet, contributing to the prevention or induction of diabetes eventually. In general, in the upcoming future, one of the emerging strategies for the prevention and control of diabetes may modulate gut microbiota through precise dietary strategies.