Clinical, hormonal and molecular-genetic characteristics of monogenic diabetes mellitus associated with the mutations in the <i>INS</i> gene

Background: Currently more than 50 mutations of the INS gene are known to affect the various stages of insulin biosynthesis in the beta cells of the pancreas. However only individual cases of diabetes mellitus (DM) associated with heterozygous mutations in the coding region of the INS gene were reported in Russian Federation. We report a group of patients with a clinical manifestation of DM caused by mutations in both coding and non-coding regions of the INS gene. The patients with a mutation in the intron of the INS gene are reported for the first time in Russian FederationMaterials and methods: 60 patients with an isolated course of neonatal DM (NDM), 52 patients with a manifestation of DM at the age of 7–12 months and the absence of the main autoimmune markers of type 1 DM, 650 patients with the MODY phenotype were included in the study. NGS technology was used for molecular genetic research. Author’s panel of primers (Custom DNA Panel) was used for multiplex PCR and sequencing using Ion Ampliseq™ technology. The author’s panel “­Diabetes Mellitus” included 28 genes (13 candidate genes of MODY and other genes associated with DM).Results: 13 heterozygous mutations were identified in 16 probands and 9 relatives. The majority of mutations were detected in patients with PNDM (18.75%) and in patients with an onset of DM at the age of 7–12 months (9.6%). Mutations in the INS gene were detected in 2 patients (0.3%) in the group with the MODY phenotype. Mutations in the INS gene were not detected in patients with transient NDM (TNDM). Analysis of clinical data in patients with PND and onset of diabetes at the age of 7–12 months did not show significant differences in the course of the disease. The clinical characteristics of the cases of MODY10 and diabetes caused by a mutation in the intron of the INS gene are reported in details.Conclusion: The role of INS gene mutations in NDM, MODY, and DM with an onset at the age of 7–12 months was analyzed in a large group of patients. The clinical characteristics of DM due to a mutation in the intron of the INS gene are reported for the first time in the Russian Federation

Direct reprogramming of human fibroblasts into dopaminergic neuron-like cells

Transplantation of exogenous dopaminergic neuron (DA neurons) is a promising approach for treating Parkinson's disease (PD). However, a major stumbling block has been the lack of a reliable source of donor DA neurons. Here we show that a combination of five transcriptional factors Mash1, Ngn2, Sox2, Nurr1, and Pitx3 can directly and effectively reprogram human fibroblasts into DA neuron-like cells. The reprogrammed cells stained positive for various markers for DA neurons. They also showed characteristic DA uptake and production properties. Moreover, they exhibited DA neuron-specific electrophysiological profiles. Finally, they provided symptomatic relief in a rat PD model. Therefore, our directly reprogrammed DA neuron-like cells are a promising source of cell-replacement therapy for PD

MELAS syndrome as a unusual cause of hypoparathyroidism: clinical case

MELAS syndrome belongs to the group of progressive mitochondrial diseases associated with point mutations in mitochondrial DNA, and includes mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes, which can combined with endocrine disorders (thyroid, parathyroid and pancreas). The frequency of hypoparathyroidism in the framework of the syndrome is less than 0.5%. Verification of the MELAS syndrome is associated with certain difficulties due to low incidence of the disease and variety of clinical manifestations and requires continuity in the work of doctors of various specialties: neurologists, endocrinologists and audiologists. Confirmation of the diagnosis is carried out by molecular genetic test of mitochondrial DNA in lymphocytes, in some cases muscle tissue biopsy analysis. In the article, we present a rare diagnosis case young patient with MELAS syndrome based on the presence of unclear hypoparathyroidism in combination with neurological symptoms, diabetes mellitus, lactic acidosis and hearing loss. MELAS syndrome was confirmed by a genetic blood test. In the debut of hypoparathyroidism, diabetes mellitus, hypothyroidism of the MELAS syndrome were easily compensated on replacement therapy

Three Ubiquitin Conjugation Sites in the Amino Terminus of the Dopamine Transporter Mediate Protein Kinase C–dependent Endocytosis of the Transporter

Dopamine levels in the brain are controlled by the plasma membrane dopamine transporter (DAT). The amount of DAT at the cell surface is determined by the relative rates of its internalization and recycling. Activation of protein kinase C (PKC) leads to acceleration of DAT endocytosis. We have recently demonstrated that PKC activation also results in ubiquitylation of DAT. To directly address the role of DAT ubiquitylation, lysine residues in DAT were mutated. Mutations of each lysine individually did not affect ubiquitylation and endocytosis of DAT. By contrast, ubiquitylation of mutants carrying multiple lysine substitutions was reduced in cells treated with phorbol ester to the levels detected in nonstimulated cells. Altogether, mutagenesis data suggested that Lys19, Lys27, and Lys35 clustered in the DAT amino-terminus are the major ubiquitin-conjugation sites. The data are consistent with the model whereby at any given time only one of the lysines in DAT is conjugated with a short ubiquitin chain. Importantly, cell surface biotinylation, immunofluorescence and down-regulation experiments revealed that PKC-dependent internalization of multilysine mutants was essentially abolished. These data provide the first evidence that the ubiquitin moieties conjugated to DAT may serve as a molecular interface of the transporter interaction with the endocytic machinery

Studies on the mechanism of action of dextrin−phospholipase A₂and its suitability for use in combination therapy

The bioresponsive conjugate dextrin−phospholipase A2 (PLA2) is a novel anticancer polymer therapeutic. Dextrin conjugation decreases PLA2 bioactivity, but this can be restored following triggered degradation by α-amylase. The conjugate displays reduced hemolytic activity but retains, or shows enhanced, cytotoxicity in vitro that partially correlates with epidermal growth factor receptor (EGFR) expression. Here, we investigate further the mechanism of action of dextrin−PLA2 with the aim of judging its potential for combination with tyrosine kinase inhibitors (TKI) and/or chemotherapy and selecting the first models for in vivo evaluation. The endocytic fate of Oregon Green (OG)-labeled probes was assessed in MCF-7 cells. Whereas PLA2-OG showed greatest membrane binding, the dextrin−PLA2-OG conjugate displayed higher internalization. Moreover, cells incubated with PLA2-OG and dextrin−PLA2-OG showed an altered pattern of intracellular vesicle distribution compared to dextrin−OG. When cell lines known to express different levels of EGFR were used to assess cytotoxicity, free PLA2 activity was enhanced by addition of EGF whereas the conjugate was less cytotoxic, perhaps due to differences in their PK/PD profile. Co-incubation of cells with the TKI inhibitor, gefitinib, led to reduced cytotoxicity of both PLA2 and dextrin−PLA2 suggesting a TK-mediated PLA2 mechanism of action. However, the enhanced cytotoxicity seen in the presence of doxorubicin suggested potential for development of a dextrin−PLA2/doxorubicin combination therapy