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Maturity-Onset Diabetes of the Young (MODY) is a diabetes mellitus subtype caused by a single gene. The detection rate of the responsible gene is 27% in the United Kingdom, indicating that the causative gene remains unknown in the majority of clinically diagnosed MODY cases. To improve the detection rate, we applied comprehensive genetic testing using whole exome sequencing (WES) followed by Multiplex Ligation-dependent Probe Amplification (MLPA) and functional analyses. Twenty-one unrelated Japanese participants with MODY were enrolled in the study. To detect copy number variations (CNVs), WES was performed first, followed by MLPA analysis for participants who were negative on the basis of WES. Undetermined variants were analyzed according to their functional properties. WES identified 7 pathogenic and 3 novel likely pathogenic variants in the 21 participants. Functional analyses revealed that 1 in 3 variants was pathogenic. MLPA analysis applied to the remaining 13 undetermined samples identified 4 cases with pathogenic CNVs: 3 in HNF4A and 1 in HNF1B. Pathogenic variants were identified in 12 participants (12/21, 57.1%) - relatively high rate reported to date. Notably, one-third of the participants had CNVs in HNF4A or HNF1B, indicating a limitation of WES-only screening.
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Variaciones en el Número de Copia de ADN , Diabetes Mellitus Tipo 2 , Secuenciación del Exoma , Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/epidemiología , Pueblos del Este de Asia/genética , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Factor Nuclear 1-beta del Hepatocito/genética , Factor Nuclear 4 del Hepatocito/genética , Japón/epidemiología , Reacción en Cadena de la Polimerasa Multiplex , Mutación , PrevalenciaRESUMEN
Glucokinase is a glycolytic enzyme that catalyzes the phosphorylation of glucose to glucose-6-phospate in the first step of the glycolytic pathway. It also regulates the threshold for insulin secretion from pancreatic beta cells by catalyzing the phosphorylation of glucose and plays an important role as a glucose sensor. Pathogenic variants in the glucokinase gene (GCK) cause non-progressive but persistent mild fasting hyperglycemia, also recognized as maturity-onset diabetes of the young 2 (MODY2). This report presents the case of two Japanese siblings with MODY2, who were initially diagnosed with impaired glucose intolerance at 20 and 17 years of age, and later developed diabetes mellitus. They had no history of obesity, were negative for islet-related autoantibodies and their serum C-peptide level were within the normal range. Diabetic complications were not observed. Next-generation sequencing revealed a novel heterozygous variant in GCK (NM_000162.5: c.1088A>G, p.Asp363Gly) in both siblings. This variant has not been reported previously. In silico functional analyses, using SIFT and MutationTaster, suggested that the variant was damaging. To confirm the functional impact of the mutated GCK, the HiBiT-tagged p.Asp363Gly variant and the wild-type GCK were transiently expressed in HEK293T cells. The cells expressing the variant GCK exhibited 79% less bioluminescence, compared to those expressing the wild-type GCK, suggesting that the pathophysiology of the variant was a result of haploinsufficiency.
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Diabetes Mellitus Tipo 2 , Glucoquinasa , Humanos , Glucoquinasa/genética , Glucoquinasa/metabolismo , Mutación , Pueblos del Este de Asia , Células HEK293 , Hermanos , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/diagnóstico , GlucosaRESUMEN
OBJECTIVE: Resting energy expenditure (REE) is an important tool in nutrition management, especially in type 2 diabetes mellitus (T2DM). The predicted REE (pREE) was reported to be inaccurate, compared with measured REE (mREE) in Japanese T2DM patients. Despite the accuracy of REE, measured via indirect calorimetry (mREE), the technique is demanding. This study evaluated the associated clinical factors of the difference between pREE and mREE in Japanese patients with T2DM. METHODS: Forty-nine Japanese patients with T2DM but no severe complications (32 men and 17 women) were enrolled. mREE was determined via indirect calorimetry. RESULTS: Participants average age was 56.3 ± 11.0 years, body mass index was 25.2 ± 3.6 kg/m2, and HbA1c was 9.6 ± 1.6%. The mean mREE was 1099 ± 212 kcal/day. Age, body mass index, hemoglobin, and uric acid levels were all associated with mREE by simple regression; of these, body weight was the significant factor in the multiple regression analysis. When the patients were divided into tertiles, the average mREE values were lower than the pREE values for each group. The difference between mREE and pREE was largest in the lowest value group, whose subjects were mostly women aged over 50 years. This group of women showed significantly lower mREE (904 ± 121 kcal) in comparison with men in the same age group, with 26% overestimation of pREE, even when the equation that yielded the closest mREE value was used. CONCLUSION: The previously reported pREE overestimates mREE in Japanese patients with T2DM, especially in postmenopausal women.
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Maturity-onset diabetes of the young (MODY) is a heterozygous monogenic diabetes; more than 14 disease genes have been identified. However, the pathogenesis of MODY is not fully understood because the patients' pancreatic beta cells are inaccessible. To elucidate the pathology of MODY, we established MODY3 patient-derived iPS (MODY3-iPS) cells using non-integrating Sendai virus (SeV) vector and examined the mutant mRNA and protein of HNF1A (Hepatocyte Nuclear factor 1A) after pancreatic lineage differentiation. Our patient had a cytosine insertion in the HNF1A gene (P291fsinsC) causing frameshift and making a premature termination codon (PTC). We confirmed these MODY3-iPS cells possessed the characteristics of pluripotent stem cells. After we differentiated them into pancreatic beta cells, transcripts of HNF1A gene were cloned and sequenced. We found that P291fsinsC mutant transcripts were much less frequent than wild ones, but they increased after adding cycloheximide (CHX) to the medium. These results suggested that mutant mRNA was destroyed by nonsense-mediated mRNA decay (NMD). Moreover, we were not able to detect any band of mutant proteins in pancreatic lineage cells which were differentiated from MODY3-iPSCs by western blot (WB) analysis. A scarcity of the truncated form of mutant protein may indicate that MODY3 might be caused by a haplo-insufficiency effect rather than a dominant negative manner.
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Diabetes Mellitus Tipo 2/metabolismo , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Células Madre Pluripotentes Inducidas/patología , Células Secretoras de Insulina/patología , Mutación , ARN Mensajero/genética , Células Cultivadas , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patología , Femenino , Haploinsuficiencia , Factor Nuclear 1-alfa del Hepatocito/genética , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Células Secretoras de Insulina/metabolismo , ARN Mensajero/metabolismoRESUMEN
AIMS/INTRODUCTION: Resting energy expenditure was associated with a serum bone turnover marker in postmenopausal women with type 2 diabetes (T2DMPW) in the present cross-sectional study. To clarify the fundamental pathological factor for the correlation of bone metabolism and basal metabolism in type 2 diabetes, a 6-month prospective follow-up study was carried out with supplementation of vitamin D. MATERIALS AND METHODS: A total of 44 T2DMPW were enrolled. The following factors were evaluated at the beginning and the end of the summer: procollagen type 1 N-terminal propeptide, carboxy-terminal collagen crosslinks-1, intact parathyroid hormone and 25-hydroxyvitamin D (25[OH]D), as well as diabetic complications, body composition, respiratory quotient and resting energy expenditure. A total of 23 patients with low 25(OH)D levels (Ë20 ng/mL) were instructed to increase vitamin D levels by lifestyle change. Among them, 15 patients with osteoporosis were also administered alfacalcidol. RESULTS: Serum 25(OH)D increased in 25 patients and decreased in 19 patients. Patients who did not receive the study intervention at the start tended to have a decreased 2525(OH)D level; therefore, the average 25(OH)D level of all patients was not changed. Changes in resting energy expenditure were positively correlated with those of procollagen type 1 N-terminal propeptide/carboxy-terminal collagen crosslinks-1. Changes in the respiratory quotient correlated with the mean glycated hemoglobin levels; procollagen type 1 N-terminal propeptide levels positively correlated with serum 25(OH)D after the intervention. These correlations were prominent in patients with increased 25(OH)D and those with alfacalcidol supplementation. CONCLUSIONS: Restoration of vitamin D level might be a prerequisite for a normal correlation between bone and basal metabolism in T2DMPW. Lifestyle intervention for retention of vitamin D level is important even in summer, in T2DMPW.
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Huesos/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/metabolismo , Metabolismo Energético , Posmenopausia , Vitamina D/sangre , Anciano , Biomarcadores/sangre , Diabetes Mellitus Tipo 2/complicaciones , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Osteoporosis Posmenopáusica/sangre , Osteoporosis Posmenopáusica/etiología , Estudios ProspectivosRESUMEN
The recent advent of noninvasive prenatal testing (NIPT) has had a significant impact in the field of prenatal testing. Although reports on pregnant women who used NIPT have accumulated, little is known about the experiences of their male partners. In this study, we assessed the experiences of couples who were expecting a child and undergoing NIPT, with a focus on both the pregnant women and their partners. Questionnaires were administered to 282 participants focusing on their specific experiences at three time points: after pre-test counseling (first visit), when undergoing NIPT (second visit), and when results were received (third visit). Responses were analyzed to assess the differences between pregnant women and their partners. We found that more partners selected "family" as their first information source about NIPT and "my partner" as the first person to request NIPT than did pregnant women (35.6 vs. 5.9 %; p < 0.001 and 19.3 vs.1.5 %; p < 0.001). However, pregnant women more often consulted others including family and friends until undergoing NIPT than their partners (89.1 vs. 54.6 %; p < 0.001). Our findings suggest that it is important to encourage male partners to be actively involved in the NIPT decision-making process. Differences between pregnant women and their partners should be seriously considered when providing genetic counseling.
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Asesoramiento Genético , Pruebas Genéticas , Diagnóstico Prenatal , Esposos , Adulto , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , EmbarazoRESUMEN
The hepatocyte nuclear factor 1ß gene (HNF1B) is responsible for maturity-onset diabetes of the young type 5 (MODY5), which is characterized by early-onset diabetes mellitus and urogenital malformations. HNF1B is expressed during visceral endoderm formation. We identified a disruption of the great pancreatic artery in a patient with MODY5 with no pancreatic body or tail. Our finding supports the significance of HNF1B in the development of the pancreas.
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OBJECTIVE: Diabetes is a risk factor for osteoporosis, and glycemic control is critical during osteoporosis treatment in patients with type 2 diabetes (T2D). However, diabetic therapies have potentially adverse effects on bone metabolism. Additionally, biomarkers for bone metabolism are directly affected by drug therapies for osteoporosis. This study examined resting energy expenditure (REE) and respiratory quotient (RQ) as indices of bone metabolism in postmenopausal Japanese women with T2D. METHODS: Forty-six postmenopausal Japanese women with T2D were examined. Procollagen type 1 N-terminal propeptide (P1NP, a fasting serum bone formation marker) and carboxy-terminal collagen cross-links-1 (CTX-1, a resorption marker) were evaluated, along with intact parathyroid hormone, 25-hydroxyvitamin D (25[OH]D), urine microalbumin, motor nerve conduction velocity, sensory nerve conduction velocity, R-R interval, body composition, REE, RQ, and bone mineral density at the nondominant distal radius. RESULTS: The mean T-score was low with high variance (-1.7 ± 1.6), and 18 patients (39%) met the criteria for osteoporosis. REE was positively correlated with body mass index (ß = 0.517; r(2) = 0.250), serum calcium (ß = 0.624; r(2) = 0.200), glycated hemoglobin A1C for the previous 6 mo (ß = 0.395; r(2) = 0.137), and the serum P1NP/CTX-1 ratio (ß = 0.380; r(2) = 0.144). RQ was positively correlated with serum 25(OH)D (ß = 0.387; r(2) = 0.131). CONCLUSION: The basal metabolic rate and diabetic pathophysiology are interrelated with bone turnover.
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Metabolismo Basal , Densidad Ósea , Remodelación Ósea , Huesos/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Osteoporosis Posmenopáusica/etiología , Descanso/fisiología , Anciano , Biomarcadores/sangre , Índice de Masa Corporal , Calcio/sangre , Colágeno Tipo I/sangre , Diabetes Mellitus Tipo 2/metabolismo , Femenino , Hemoglobina Glucada/metabolismo , Humanos , Japón/epidemiología , Persona de Mediana Edad , Osteoporosis Posmenopáusica/epidemiología , Osteoporosis Posmenopáusica/metabolismo , Fragmentos de Péptidos/sangre , Péptidos/sangre , Posmenopausia , Procolágeno/sangre , Respiración , Vitamina D/análogos & derivados , Vitamina D/sangreRESUMEN
Maturity-onset diabetes of the young (MODY) is a heterozygous monogenic diabetes; more than 13 disease genes have been identified. However, the pathogenesis of MODY is not fully understood, because the pancreatic ß-cells of the patients are inaccessable. Therefore, we attempted to establish MODY patient-derived induced pluripotent stem cells (MODY-iPS) cells to investigate the pathogenic mechanism of MODY by inducing pancreatic ß-cells. We established MODY5-iPS cells from a Japanese patient with MODY5 (R177X), and confirmed that MODY5-iPS cells possessed the characteristics of pluripotent stem cells. In the course of differentiation from MODY5-iPS cells into pancreatic ß-cells, we examined the disease gene, HNF1B messenger ribonucleic acid. We found that the amount of R177X mutant transcripts was much less than that of wild ones, but they increased after adding cycloheximide to the medium. These results suggest that these R177X mutant messenger ribonucleic acids are disrupted by nonsense-mediated messenger ribonucleic acid decay in MODY-iPS cells during the developmental stages of pancreatic ß-cells.
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A 19-year-old Japanese woman had been diagnosed with diabetes at the age of 9 years. She had a strong family history of diabetes, and genetic screening showed she had maturity-onset diabetes of the young type 3 (MODY3). Ultrasonography of the liver and magnetic resonance imaging showed multiple nodules consistent with hepatocellular adenoma (HA). Biopsy of the liver tumors revealed hepatocyte nuclear factor (HNF) 1α-inactivated HA. HA is known as a MODY3-related disease due to mutations in HNF1α. We present the first report of HA associated with MODY3 in Japan.
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Adenoma de Células Hepáticas/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Neoplasias Hepáticas/metabolismo , Adenoma de Células Hepáticas/complicaciones , Adenoma de Células Hepáticas/genética , Femenino , Factor Nuclear 1-alfa del Hepatocito/genética , Humanos , Neoplasias Hepáticas/complicaciones , Neoplasias Hepáticas/genética , Mutación , Linaje , Adulto JovenRESUMEN
Glucagon-like peptide (GLP)-1 analog based therapies are used not only for their insulinotropic effects, but also for their pleiotropic effects that improve pancreatic ß cell function. Liraglutide is a long acting derivative of human GLP-1(7-37), which is a cleavage product encompassing amino acids 7-37 of GLP-1. In this study, we examined whether Liraglutide treatment restore the glucose-stimulated mitochondrial response of ß cells with chemically induced mitochondrial damage. We tested three GLP-1-related proteins: human GLP-1(1-37), GLP-1(7-37) and Liraglutide. To measure changes of the mitochondrial pH quantitatively in real-time, we have developed a bioengineered ß cell line. We generated a mitochondrial damaged model by treating ß cells with ethidium bromide (EtBr; 0.5 or 1 µg/mL for 48 h). EtBr treatment reduced the response to 25 mM glucose in mitochondrial pH in a dose- and time-dependent manner. GLP-1(7-37) (100 nM) enhanced the response of mitochondria to glucose stimulation in undamaged ß cells. Preincubation with Liraglutide (1 nM) or GLP-1 (100 nM) for 3h recovered the mitochondrial response to glucose in damaged ß cells, however, GLP-1(7-37) (100 nM) did not. When GLP-1(7-37) was administered in stepwise increments (i.e., starting with 20 nM to reach 100 nM in 3h), similar recovery of the mitochondrial function was observed. The results suggest that Liraglutide is effective to recover glucose-stimulated mitochondrial response in damaged ß cells.
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Péptido 1 Similar al Glucagón/análogos & derivados , Células Secretoras de Insulina/efectos de los fármacos , Membranas Mitocondriales/efectos de los fármacos , Animales , Etidio/toxicidad , Péptido 1 Similar al Glucagón/farmacología , Glucosa/farmacología , Humanos , Liraglutida , Fragmentos de Péptidos/farmacología , RatasRESUMEN
OBJECTIVE: The paper aims to explore effective measures and strategies for the promotion of ICT-enabled innovations for the elderly and people with special needs. METHODS: The paper begins by reviewing current government initiatives in the field of e-health and accessibility that are addressing challenges faced by Japan's rapidly ageing society. It then evaluates the results of Japanese government efforts in the promotion of ICT solutions for its older population against the availability of special infrastructure, device interfaces, and services and applications that meet five essential needs of the elderly with regard to quality of life in highly developed countries. RESULTS AND CONCLUSION: The results of the study suggest that more efforts are needed to exploit ICT to transform all domains of society in order to meet the challenges produced by a rapidly ageing population. For that purpose the paper proposes 12 main areas in which to facilitate ICT innovations for an ageing population. It then outlines a number of strategic directions for the formulation of specific measures that will place Japan in the forefront of societal transformation.
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Envejecimiento , Sistemas de Información , Telecomunicaciones , Anciano , Necesidades y Demandas de Servicios de Salud , Humanos , Japón , Movimiento , Calidad de Vida , SeguridadRESUMEN
Potassium inwardly rectifying channel, subfamily J, member 15 (KCNJ15) is a type 2 diabetes-associated risk gene, and Kcnj15 overexpression suppresses insulin secretion in rat insulinoma (INS1) cells. The aim of the current study was to characterize the role of Kcnj15 by knockdown of this gene in vitro and in vivo. Human islet cells were used to determine the expression of KCNJ15. Expression of KCNJ15 mRNA in islets was higher in subjects with type 2 diabetes. In INS1 cells, Kcnj15 expression was induced by high glucose-containing medium. Regulation of Kcnj15 by glucose and its effect on insulin secretion were analyzed in INS1 cells and in normal mice and diabetic mice by the inactivation of Kcnj15 using small interfering RNA. Knockdown of Kcnj15 increased the insulin secretion in vitro and in vivo. KCNJ15 and Ca(2+)-sensing receptor (CsR) interact in the kidney. Binding of Kcnj15 with CsR was also detected in INS1 cells. In conclusion, downregulation of Kcnj15 leads to increased insulin secretion in vitro and in vivo. The mechanism to regulate insulin secretion involves KCNJ15 and CsR.
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Diabetes Mellitus Tipo 2/genética , Predisposición Genética a la Enfermedad , Glucosa/administración & dosificación , Insulina/metabolismo , Canales de Potasio de Rectificación Interna/genética , Animales , Glucemia/metabolismo , Células Cultivadas , Diabetes Mellitus Tipo 2/metabolismo , Femenino , Humanos , Insulina/sangre , Secreción de Insulina , Insulinoma/metabolismo , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Canales de Potasio de Rectificación Interna/metabolismo , ARN Interferente Pequeño/administración & dosificación , Ratas , Ratas Sprague-Dawley , Receptores Sensibles al Calcio/metabolismoRESUMEN
Mitochondrial pH is a key determinant of mitochondrial energy metabolism. We have developed a new fluorescence-based ratiometric pH biosensor using a chloride-insensitive and hydrogen-sensitive probe for direct, quantitative and bleaching-free measurement in a living cell. Fusing this biosensor with a mitochondrial localization signal (MTpHGV) allowed us to determine mitochondrial pH. This new system was applied to measure mitochondrial pH in pancreatic ß-cells, in which mitochondrial function plays a pivotal role in insulin secretion. Rat INS1 cells and mouse MIN6 cells are transfected with MTpHGV stably to monitor mitochondrial pH. While carbonyl cyanide 3-chlorophenylhydrazone (CCCP) treatment rapidly decreased mitochondrial pH in cultured rat MTpHGV-INS-1 cells, MTpHGV-MIN6 cells showed a rapid increase. These data suggest that MTpHGV probe exist in matrix side in INS-1 cells, but on the outer side of mitochondrial inner membrane in MIN6 cells. Moreover, while MTpHGV-INS-1 cells showed a rapid increase of pH by glucose stimulation, mitochondrial pH decreased quickly by glucose stimulation in all MTpHGV-MIN6 cells examined and recovered smoothly. Perfusion study of glucose load in MTpHGV-MIN6 cells under aminooxyacetate (AOA) or 100µM diazoxide showed that this mitochondrial pH acidification was dependent on nicotinamide adenine dinucleotide (NADH) shuttle, but independent from KATP channel. This new system for measuring mitochondrial pH is sensitive across the range of physiologic conditions and may be a useful tool for evaluating mitochondrial function in living cells.
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Técnicas Biosensibles , Células Secretoras de Insulina/química , Mitocondrias/química , Ácido Aminooxiacético/farmacología , Animales , Calcio/metabolismo , Carbonil Cianuro m-Clorofenil Hidrazona/farmacología , Línea Celular , Diazóxido/farmacología , Glucosa/farmacología , Concentración de Iones de Hidrógeno , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Ratones , Ionóforos de Protónes/farmacología , RatasRESUMEN
UNLABELLED: Aims/Introduction: Mutations in hepatocyte nuclear factor-4α (HNF4α) lead to various diseases, among which C-terminal deletions of HNF4α are exclusively responsible for maturity onset diabetes of the young 1 (MODY1). MODY is an autosomal dominant disease characterized by a primary defect in insulin response to glucose, suggesting that the C-terminus of HNF4α is important for pancreatic ß-cell function. To clarify the role of the C-terminus of HNF4α, changes in cellular localization and the binding ability to its regulator were examined, specifically in the region containing Q268, which deletion causes MODY1. MATERIALS AND METHODS: Cellular localization of mutant HNF4α were examined in monkey kidney 7 (COS7), Chinese hamster ovary, rat insulinoma and mouse insulinoma cells, and their binding activity to other proteins were examined by fluorescence resonance energy transfer (FRET) in COS7 cells. RESULTS: Although wild-type HNF4α was localized in the nucleoplasm in transfected cultured cells, Q268X-HNF4α was located predominantly in the nucleolus. Deletion analysis of the C-terminus of HNF4α showed that the S337X-HNF4α mutant, and other mutants with shorter amino acid sequences (S337-K194), were mostly localized in the nucleolus. HNF4α mutants with amino acid sequences shorter than the W192X-HNF4α mutant gradually spread to the nucleoplasm in accordance with their lengths. The A250X-HNF4α mutant was capable of causing the accumulation of HNF4α or the small heterodimer partner (SHP), one of the HNF4α regulators, in the nucleolus. However, the R154X-HNF4α mutant did not have binding ability to wild-type HNF4α or SHP, and thus was seen in the nucleus. CONCLUSIONS: The C-terminus sites might play a key role in facilitating the nucleolar and subnucleolar localization of HNF4α. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00210.x, 2012).
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Organic cation transporter 1 (OCT1; SLC22A1) seems to play a role in the efficacy and disposition of the widely used antidiabetic drug metformin. Genetic variants in OCT1 have been identified largely in European populations. Metformin is increasingly being used in Asian populations where the incidence of type 2 diabetes (T2D) is on the rise. The goal of this study is to identify genetic variants of OCT1 in Chinese and Japanese populations, which may potentially modulate response to metformin. We used recent data from the 1000 Genomes Project (Chinese and Japanese) and direct sequencing of selected amplicons of OCT1 in 66 DNA samples from Japanese patients with T2D. A total of six nonsynonymous variants were identified. Three of them (Q97K, P117L, and R206C) had not been functionally characterized previously and had allele frequencies of 0.017, 0.023 and 0.008, respectively. The uptake of metformin in cells expressing Q97K, P117L, and R206C was significantly reduced relative to the OCT1 reference (62 ± 4.3, 55 ± 6.8, and 22 ± 1.5% for Q97K, P117L, and R206C, respectively). Kinetic studies indicated that P117L and R206C exhibited a reduced V(max), whereas Q97K showed an increased K(m). The green fluorescent protein (GFP)-tagged Q97K and P117L variants localized to the plasma membrane, whereas the GFP-tagged R206C was retained mainly in the endoplasmic reticulum. Replacement of the highly conserved R206 with different amino acids modulated the subcellular localization and function of the transporter. This study suggests that nonsynonymous variants of OCT1 in Chinese and Japanese populations may affect the differential response to metformin.
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Transportador 1 de Catión Orgánico/genética , Transportador 1 de Catión Orgánico/metabolismo , Anciano , Arginina/genética , Transporte Biológico Activo , Biotinilación , Western Blotting , Línea Celular , China/epidemiología , ADN/genética , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Femenino , Citometría de Flujo , Variación Genética , Genotipo , Proteínas Fluorescentes Verdes/genética , Humanos , Hipoglucemiantes/metabolismo , Japón/epidemiología , Cinética , Masculino , Metformina/metabolismo , Persona de Mediana Edad , Polimorfismo Genético , Polimorfismo de Nucleótido Simple , Alineación de SecuenciaRESUMEN
Recent advances in genome research have enabled the identification of new genomic variations that are associated with type 2 diabetes mellitus (T2DM). Via fine mapping of SNPs in a candidate region of chromosome 21q, the current study identifies potassium inwardly-rectifying channel, subfamily J, member 15 (KCNJ15) as a new T2DM susceptibility gene. KCNJ15 is expressed in the beta cell of the pancreas, and a synonymous SNP, rs3746876, in exon 4 (C566T) of this gene, with T allele frequency among control subjects of 3.1%, showed a significant association with T2DM affecting lean individuals in three independent Japanese sample sets (p = 2.5 x 10(-7), odds ratio [OR] = 2.54, 95% confidence interval [CI] = 1.76-3.67) and with unstratified T2DM (p = 6.7 x 10(-6), OR = 1.76, 95% CI = 1.37-2.25). The diabetes risk allele frequency was, however, very low among Europeans in whom no association between this variant and T2DM could be shown. Functional analysis in human embryonic kidney 293 cells demonstrated that the risk allele of the synonymous SNP in exon 4 increased KCNJ15 expression via increased mRNA stability, which resulted in the higher expression of protein as compared to that of the nonrisk allele. We also showed that KCNJ15 is expressed in human pancreatic beta cells. In conclusion, we demonstrated a significant association between a synonymous variant in KCNJ15 and T2DM in lean Japanese patients with T2DM, suggesting that KCNJ15 is a previously unreported susceptibility gene for T2DM among Asians.
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Diabetes Mellitus Tipo 2/etnología , Diabetes Mellitus Tipo 2/genética , Predisposición Genética a la Enfermedad , Canales de Potasio de Rectificación Interna/genética , Canales de Potasio de Rectificación Interna/fisiología , Adulto , Anciano , Pueblo Asiatico , Estudios de Casos y Controles , Cromosomas Humanos Par 21 , Femenino , Humanos , Células Secretoras de Insulina/metabolismo , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido SimpleRESUMEN
Type 1 diabetic patients who have endured their condition for prolonged periods are not uncommon, but there are few well-documented cases of type 2 diabetic patients with duration of over fifty years. In the present case study, we analyzed the history of a diabetic patient whose duration was 53 years. Her case was consequently diagnosed not as the common type 2 diabetes, but as the slowly progressive type 1 diabetes (SPIDDM) identified by Japanese medical researchers. The patient, now 73 years old, was first diagnosed with diabetes in 1953 when she was 17 years of age and started insulin injections. In 1962 she was referred to our hospital, and two years later she vaginally delivered a healthy baby (birth weight 3100 g) at the 40(th) week of gestation. She was the first case of a diabetic mother delivering an infant treated at Tokyo Women's Medical College Hospital. Her data shows that her C-peptide responses by meal tolerance test in 1978 was at least partly preserved though it decreased year by year. Her anti-GAD antibody was found to be positive in 2000 and remained so in 2009. This leads us to conclude that the etiology of her SPIDDM was most likely has insulin secretion exhaustion.
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Diabetes Mellitus Tipo 1/tratamiento farmacológico , Adolescente , Anciano , Péptido C/metabolismo , Diabetes Mellitus Tipo 1/complicaciones , Progresión de la Enfermedad , Femenino , Glutamato Descarboxilasa/inmunología , Humanos , Hipertiroidismo/etiología , Recién Nacido , Insulina/metabolismo , Insulina/uso terapéutico , Secreción de Insulina , Masculino , Embarazo , Embarazo en DiabéticasRESUMEN
Prediction of the disease status is one of the most important objectives of genetic studies. To select the genes with strong evidence of the association with type 2 diabetes mellitus, we validated the associations of the seven candidate loci extracted in our earlier study by genotyping the samples in two independent sample panels. However, except for KCNQ1, the association of none of the remaining seven loci was replicated. We then selected 11 genes, KCNQ1, TCF7L2, CDKAL1, CDKN2A/B, IGF2BP2, SLC30A8, HHEX, GCKR, HNF1B, KCNJ11 and PPARG, whose associations with diabetes have already been reported and replicated either in the literature or in this study in the Japanese population. As no evidence of the gene-gene interaction for any pair of the 11 loci was shown, we constructed a prediction model for the disease using the logistic regression analysis by incorporating the number of the risk alleles for the 11 genes, as well as age, sex and body mass index as independent variables. Cumulative risk assessment showed that the addition of one risk allele resulted in an average increase in the odds for the disease of 1.29 (95% CI=1.25-1.33, P=5.4 x 10(-53)). The area under the receiver operating characteristic curve, an estimate of the power of the prediction model, was 0.72, thereby indicating that our prediction model for type 2 diabetes may not be so useful but has some value. Incorporation of data from additional risk loci is most likely to increase the predictive power.