Association between basal metabolic function and bone metabolism in postmenopausal women with type 2 diabetes.

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.

[Hepatocyte nuclear factor 1α-inactivated hepatocellular adenomatosis in a patient with maturity-onset diabetes of the young type 3: case report and literature review].

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.

Inhibition of glucose-stimulated insulin secretion by KCNJ15, a newly identified susceptibility gene for type 2 diabetes.

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.

Impact of variants in the VEGF gene on progression of proliferative diabetic retinopathy.

BACKGROUND: The development of diabetic retinopathy is associated with the duration of diabetes and HbA1c levels. However, the familial aggregation of diabetic retinopathy is consistent with genetic susceptibility. Recently, a -634C/G polymorphism in the vascular endothelial growth factor (VEGF) gene was shown to be associated with diabetic retinopathy. To clarify the contribution of the VEGF gene in the development of diabetic retinopathy we analyzed variants in this gene among 469 Japanese patients with type 2 diabetes. METHODS: DNA from each patient was typed for -634C/G and -2578C/A polymorphisms using conventional polymerase chain reaction techniques. The vitreous fluid samples were obtained from 40 patients with PDR for measurement of VEGF levels. RESULTS: We found a significantly higher frequency of the A allele in the group with proliferative diabetic retinopathy (PDR) than in the control group at -2578C/A polymorphism (p = 0.036). Moreover, if the subjects were grouped according to the duration of diabetes and status of diabetic retinopathy (a first group consisting of subjects with longer duration (>20 y) of diabetes without any retinopathy (n = 102), and a second group of those with shorter diabetes (<15 y) but having retinopathy (n = 35), the genotype distribution at -2578 C/A polymorphism was again significantly higher in the second group (p = 0.005) and differed significantly (p = 0.002) in a recessive model. The risk of the AA for PDR was 7.7 (95%, CI: 1.8-30.9). CONCLUSIONS: The AA genotype at -2578C/A polymorphism in the VEGF gene is associated with proliferative diabetic retinopathy. No significant association with -634 C/G polymorphism was confirmed.

Genetic variants in the calpain-10 gene and the development of type 2 diabetes in the Japanese population.

Variation in the gene encoding the cysteine protease calpain-10 has been linked and associated with risk of type 2 diabetes. We have examined the effect of three polymorphisms in the calpain-10 gene (SNP-43, Indel-19, and SNP-63) on the development of type 2 diabetes in the Japanese population in a pooled analysis of 927 patients and 929 controls. We observed that SNP-43, Indel-19, and SNP-63 either individually or as a haplotype were not associated with altered risk of type 2 diabetes with the exception of the rare 111/221 haplogenotype (odds ratio (OR) =3.53, P=0.02). However, stratification based on the median age-at-diagnosis in the pooled study population (<50 and > or =50 years) revealed that allele 2 of Indel-19 and the 121 haplotype were associated with reduced risk in patients with later age-at-diagnosis (age-at-diagnosis > or =50 years OR=0.82 and 0.80, respectively; P=0.04 and 0.02). Thus, variation in the calpain-10 gene may affect risk of type 2 diabetes in Japanese, especially in older individuals.

Nuclear translocation of SHP and visualization of interaction with HNF-4alpha in living cells.

Mutations in small heterodimer partner (SHP) and hepatocyte nuclear factor 4alpha (HNF4alpha) are associated with mild obesity and diabetes mellitus, respectively. Both receptors work together to determine the normal pancreatic beta-cell function. We examined their subcellular localization and interaction in living cells by tagging them with yellow and cyan variants of green fluorescent protein (GFP) variants. Expressed SHP resided only in the cytoplasm in COS-7 cells which lacks HNF4alpha, but predominantly in the nucleus in insulinoma cells (MIN6). HNF4alpha was localized exclusively in the nuclei of both cells, coexpressed with HNF4alpha in COS-7 cells, redistributed in the nucleus, depending on the amount of HNF4alpha. We found fluorescence resonance energy transfer between GFP-tagged SHP and HNF4alpha, indicating a specific close association between them in the nucleus. The results strongly suggest that SHP exists primarily in the cytoplasm and is translocated into the nucleus on interacting with its nuclear receptor partner HNF4alpha.