Olfactory receptors are expressed in pancreatic ß-cells and promote glucose-stimulated insulin secretion.

Olfactory receptors (ORs) mediate olfactory chemo-sensation in OR neurons. Herein, we have demonstrated that the OR chemo-sensing machinery functions in pancreatic ß-cells and modulates insulin secretion. First, we found several OR isoforms, including OLFR15 and OLFR821, to be expressed in pancreatic islets and a ß-cell line, MIN6. Immunostaining revealed OLFR15 and OLFR821 to be uniformly expressed in pancreatic ß-cells. In addition, mRNAs of Olfr15 and Olfr821 were detected in single MIN6 cells. These results indicate that multiple ORs are simultaneously expressed in individual ß-cells. Octanoic acid, which is a medium-chain fatty acid contained in food and reportedly interacts with OLFR15, potentiated glucose-stimulated insulin secretion (GSIS), thereby improving glucose tolerance in vivo. GSIS potentiation by octanoic acid was confirmed in isolated pancreatic islets and MIN6 cells and was blocked by OLFR15 knockdown. While Gα olf expression was not detectable in ß-cells, experiments using inhibitors and siRNA revealed that the pathway dependent on phospholipase C-inositol triphosphate, rather than cAMP-protein kinase A, mediates GSIS potentiation via OLFR15. These findings suggest that the OR system in pancreatic ß-cells has a chemo-sensor function allowing recognition of environmental substances obtained from food, and potentiates insulin secretion in a cell-autonomous manner, thereby modulating systemic glucose metabolism.

A hepatic amino acid/mTOR/S6K-dependent signalling pathway modulates systemic lipid metabolism via neuronal signals.

Metabolism is coordinated among tissues and organs via neuronal signals. Levels of circulating amino acids (AAs), which are elevated in obesity, activate the intracellular target of rapamycin complex-1 (mTORC1)/S6kinase (S6K) pathway in the liver. Here we demonstrate that hepatic AA/mTORC1/S6K signalling modulates systemic lipid metabolism via a mechanism involving neuronal inter-tissue communication. Hepatic expression of an AA transporter, SNAT2, activates the mTORC1/S6K pathway, and markedly elevates serum triglycerides (TGs), while downregulating adipose lipoprotein lipase (LPL). Hepatic Rheb or active-S6K expression have similar metabolic effects, whereas hepatic expression of dominant-negative-S6K inhibits TG elevation in SNAT2 mice. Denervation, pharmacological deafferentation and ß-blocker administration suppress obesity-related hypertriglyceridemia with adipose LPL upregulation, suggesting that signals are transduced between liver and adipose tissue via a neuronal pathway consisting of afferent vagal and efferent sympathetic nerves. Thus, the neuronal mechanism uncovered here serves to coordinate amino acid and lipid levels and contributes to the development of obesity-related hypertriglyceridemia.

Wolfram syndrome in the Japanese population; molecular analysis of WFS1 gene and characterization of clinical features.

BACKGROUND: Wolfram syndrome (WFS) is a recessive neurologic and endocrinologic degenerative disorder, and is also known as DIDMOAD (Diabetes Insipidus, early-onset Diabetes Mellitus, progressive Optic Atrophy and Deafness) syndrome. Most affected individuals carry recessive mutations in the Wolfram syndrome 1 gene (WFS1). However, the phenotypic pleiomorphism, rarity and molecular complexity of this disease complicate our efforts to understand WFS. To address this limitation, we aimed to describe complications and to elucidate the contributions of WFS1 mutations to clinical manifestations in Japanese patients with WFS. METHODOLOGY: The minimal ascertainment criterion for diagnosing WFS was having both early onset diabetes mellitus and bilateral optic atrophy. Genetic analysis for WFS1 was performed by direct sequencing. PRINCIPAL FINDINGS: Sixty-seven patients were identified nationally for a prevalence of one per 710,000, with 33 patients (49%) having all 4 components of DIDMOAD. In 40 subjects who agreed to participate in this investigation from 30 unrelated families, the earliest manifestation was DM at a median age of 8.7 years, followed by OA at a median age of 15.8 years. However, either OA or DI was the first diagnosed feature in 6 subjects. In 10, features other than DM predated OA. Twenty-seven patients (67.5%) had a broad spectrum of recessive mutations in WFS1. Two patients had mutations in only one allele. Eleven patients (27.5%) had intact WFS1 alleles. Ages at onset of both DM and OA in patients with recessive WFS1 mutations were indistinguishable from those in patients without WFS1 mutations. In the patients with predicted complete loss-of-function mutations, ages at the onsets of both DM and OA were significantly earlier than those in patients with predicted partial-loss-of function mutations. CONCLUSION/SIGNIFICANCE: This study emphasizes the clinical and genetic heterogeneity in patients with WFS. Genotype-phenotype correlations may exist in patients with WFS1 mutations, as demonstrated by the disease onset.

Elevation of HDL-C in response to statin treatment is involved in the regression of carotid atherosclerosis.

AIM: Atherosclerosis is strongly associated with an increased mortality in subjects with diabetes. The carotid intima-media thickness (IMT) is commonly measured as a surrogate marker for cardiovascular risk. Statins are well-established protective agents against atherosclerosis and reportedly suppress IMT progression in subjects with diabetes. To clarify the effects of statins on subclinical atherosclerosis, we herein investigated changes in the carotid IMT and lipid profiles in a multi-center, prospective, randomized trial. METHODS: Hypercholesterolemic subjects with type 2 diabetes were randomly assigned to open-label treatment with either pravastatin or pitavastatin. The primary endpoint of this study was the IMT change after 36 months of statin treatment. RESULTS: A total of 97 subjects (51 pitavastatin; 46 pravastatin) completed this 36-month study. The LDL-C decreased significantly from 163.4 ± 27.9 mg/dl at baseline to 100.4 ± 19.6 mg/dl at 36 months in the pitavastatin group and from 159.7 ± 25.6 mg/dl to 118.5 ± 22.1 mg/dl in the pravastatin group. The mean IMT showed moderate regression in both the pitavastatin (-0.070 ± 0.215 mm, P<0.05) and the pravastatin (-0.067 ± 0.260 mm) group. However, there was no significant difference in the IMT change between the two groups. When the two groups were combined, the 36-month change in the mean IMT was significantly associated with HDL-C change (r=-0.24, P= 0.03). Multiple linear regression analysis revealed the change in HDL-C to be an independent variable showing a positive correlation with the carotid IMT reduction. CONCLUSION: The administration of statins for 3 years to subjects with type 2 diabetes resulted in a significant regression of the carotid IMT. An elevation of the plasma HDL-C with statin treatment was closely related to a regression of atherosclerosis.

Simultaneous copy number losses within multiple subtelomeric regions in early-onset type 2 diabetes mellitus.

Genetic factors play very important roles in the onset and progression of type 2 diabetes mellitus (T2DM). However, the genetic factors correlating with T2DM onset have not as yet been fully clarified. We previously found that copy number losses in the subtelomeric region on chromosome 4p16.3 were detected in early-onset Japanese T2DM patients (onset age <35 years) at a high frequency. Herein, we additionally found two novel copy number losses within the subtelomeric regions on chromosomes 16q24.2-3 and 22q13.31-33, which have significant associations with early-onset Japanese T2DM. The associations were statistically significant by Fisher's exact tests with P values of 5.19 × 10(-3) and 1.81 × 10(-3) and odds ratios of 5.7 and 4.4 for 16q24.2-3 and 22q13.31-33, respectively. Furthermore, copy number variation (CNV) analysis of the whole genome using the CNV BeadChip system verified simultaneous copy number losses in all three subtelomeric regions in 11 of our 100 T2DM subjects, while none of 100 non-diabetic controls showed the copy number losses in all three regions. Our results suggest that the mechanism underlying induction of CNVs is involved in the pathogenesis of early-onset T2DM. Thus, copy number losses within multiple subtelomeric regions are strongly associated with early-onset T2DM and examination of simultaneous CNVs in these three regions may lead to the development of an accurate and selective procedure for detecting genetic susceptibility to T2DM.

Baseline and 1-year interim follow-up assessment of Japanese patients initiating insulin therapy who were enrolled in the cardiovascular risk evaluation in people with type 2 diabetes on insulin therapy study: an international, multicenter, observational study.

BACKGROUND: The Cardiovascular Risk Evaluation in people with type 2 Diabetes on Insulin Therapy (CREDIT) study is an international, multicenter, observational study designed to assess metabolic parameters and cardiovascular risk of patients with type 2 diabetes mellitus (T2DM) on insulin therapy. The present report summarizes results at baseline and 1-year follow-up for the cohort of Japanese patients. METHODS: Male and female patients (n = 511), aged >40 years, with T2DM for >1 year, treated with insulin therapy for ≥1 month and <6 months were eligible for participation in the study. Glycemic and lipid parameters, duration of diabetes, diabetic complications, oral antidiabetic medications, and all hypoglycemic episodes were recorded. Effectiveness was assessed based on changes in clinical parameters and attainment of target HbA1c levels. Safety was evaluated based on episodes of hypoglycemia and weight gain. RESULTS: At baseline, the mean ± SD duration of diabetes was 11.8 ± 8.8 years. Microvascular and macrovascular diabetic complications were present in 83.4% and 25.1% of patients, respectively. At the 1-year follow-up, significant improvements were observed in mean HbA1c (10.3 ± 2.0% vs. 7.5 ± 1.3%, P < .001), fasting plasma glucose (217.3 ± 80.8 mg/dL vs. 139.0 ± 48.7 mg/dL, P < .001), and postprandial plasma glucose levels (296.1 ± 96.0 mg/dL vs. 178.2 ± 68.6 mg/dL, P < .001) compared with baseline. Mean total cholesterol (P < .001), low-density lipoprotein cholesterol (P < .001), triglycerides (P < .01), and diastolic blood pressure (P < .01) also significantly decreased. Good glycemic control (HbA1c < 7.0%) was achieved in 40% of patients at the 1-year follow-up. Glycemic control tended to be better in patients with lower baseline HbA1c levels (P < .01). Patients with a shorter duration of diabetes were more likely to achieve glycemic control and discontinue insulin for diabetes control at the 1-year follow-up (P < .05 for trend). Symptomatic hypoglycemic episodes occurred in 21.8% of patients over 6 to 12 months. CONCLUSIONS: Our results suggest that insulin treatment is an effective and safe therapeutic option in Japanese patients with T2DM, and earlier insulin initiation might be associated with better glycemic control.

Bach1 deficiency protects pancreatic ß-cells from oxidative stress injury.

BTB and CNC homology 1 (Bach1) is a transcriptional repressor of antioxidative enzymes, such as heme oxygenase-1 (HO-1). Oxidative stress is reportedly involved in insulin secretion impairment and obesity-associated insulin resistance. However, the role of Bach1 in the development of diabetes is unclear. HO-1 expression in the liver, white adipose tissue, and pancreatic islets was markedly upregulated in Bach1-deficient mice. Unexpectedly, glucose and insulin tolerance tests showed no differences in obese wild-type (WT) and obese Bach1-deficient mice after high-fat diet loading for 6 wk, suggesting minimal roles of Bach1 in the development of insulin resistance. In contrast, Bach1 deficiency significantly suppressed alloxan-induced pancreatic insulin content reduction and the resultant glucose elevation. Furthermore, TUNEL-positive cells in pancreatic islets of Bach1-deficient mice were markedly decreased, by 60%, compared with those in WT mice. HO-1 expression in islets was significantly upregulated in alloxan-injected Bach1-deficient mice, whereas expression of other antioxidative enzymes, e.g., catalase, superoxide dismutase, and glutathione peroxidase, was not changed by either alloxan administration or Bach1 deficiency. Our results suggest that Bach1 deficiency protects pancreatic ß-cells from oxidative stress-induced apoptosis and that the enhancement of HO-1 expression plays an important role in this protection.

Chronic mild stress alters circadian expressions of molecular clock genes in the liver.

Chronic stress is well known to affect metabolic regulation. However, molecular mechanisms interconnecting stress response systems and metabolic regulations have yet to be elucidated. Various physiological processes, including glucose/lipid metabolism, are regulated by the circadian clock, and core clock gene dysregulation reportedly leads to metabolic disorders. Glucocorticoids, acting as end-effectors of the hypothalamus-pituitary-adrenal (HPA) axis, entrain the circadian rhythms of peripheral organs, including the liver, by phase-shifting core clock gene expressions. Therefore, we examined whether chronic stress affects circadian expressions of core clock genes and metabolism-related genes in the liver using the chronic mild stress (CMS) procedure. In BALB/c mice, CMS elevated and phase-shifted serum corticosterone levels, indicating overactivation of the HPA axis. The rhythmic expressions of core clock genes, e.g., Clock, Npas2, Bmal1, Per1, and Cry1, were altered in the liver while being completely preserved in the hypothalamic suprachiasmatic nuculeus (SCN), suggesting that the SCN is not involved in alterations in hepatic core clock gene expressions. In addition, circadian patterns of glucose and lipid metabolism-related genes, e.g., peroxisome proliferator activated receptor (Ppar) α, Pparγ-1, Pparγ-coactivator-1α, and phosphoenolepyruvate carboxykinase, were also disturbed by CMS. In contrast, in C57BL/6 mice, the same CMS procedure altered neither serum corticosterone levels nor rhythmic expressions of hepatic core clock genes and metabolism-related genes. Thus, chronic stress can interfere with the circadian expressions of both core clock genes and metabolism-related genes in the liver possibly involving HPA axis overactivation. This mechanism might contribute to metabolic disorders in stressful modern societies.

Importance of endothelial NF-κB signalling in vascular remodelling and aortic aneurysm formation.

AIMS: Vascular remodelling and aortic aneurysm formation are induced mainly by inflammatory responses in the adventitia and media. However, relatively little is known about the mechanistic significance of endothelium in the pathogenesis of these vascular disorders. The transcription factor nuclear factor-kappa B (NF-κB) regulates the expressions of numerous genes, including those related to pro-inflammatory responses. Therefore, to investigate the roles of endothelial pro-inflammatory responses, we examined the impact of blocking endothelial NF-κB signalling on intimal hyperplasia and aneurysm formation. METHODS AND RESULTS: To block endothelial NF-κB signalling, we used transgenic mice expressing dominant-negative IκBα selectively in endothelial cells (E-DNIκB mice). E-DNIκB mice were protected from the development of cuff injury-induced neointimal formation, in association with suppressed arterial expressions of cellular adhesion molecules, a macrophage marker, and inflammatory factors. In addition, the blockade of endothelial NF-κB signalling prevented abdominal aortic aneurysm formation in an experimental model, hypercholesterolaemic apolipoprotein E-deficient mice with angiotensin II infusion. In this aneurysm model as well, aortic expressions of an adhesion molecule, a macrophage marker, and inflammatory factors were suppressed with the inhibited expression and activity of matrix metalloproteinases in the aorta. CONCLUSION: Endothelial NF-κB activation up-regulates adhesion molecule expression, which may trigger macrophage infiltration and inflammation in the adventitia and media. Thus, the endothelium plays important roles in vascular remodelling and aneurysm formation through its intracellular NF-κB signalling.

Hepatic glucokinase modulates obesity predisposition by regulating BAT thermogenesis via neural signals.

Considering the explosive increase in obesity worldwide, there must be an unknown mechanism(s) promoting energy accumulation under conditions of overnutrition. We identified a feed-forward mechanism favoring energy storage, originating in hepatic glucokinase (GK) upregulation. High-fat feeding induced hepatic GK upregulation, and hepatic GK overexpression dose-dependently decreased adaptive thermogenesis by downregulating thermogenesis-related genes in brown adipose tissue (BAT). This intertissue (liver-to-BAT) system consists of the afferent vagus from the liver and sympathetic efferents from the medulla and antagonizes anti-obesity effects of leptin on thermogenesis. Furthermore, upregulation of endogenous GK in the liver by high-fat feeding was more marked in obesity-prone than in obesity-resistant strains and was inversely associated with BAT thermogenesis. Hepatic GK overexpression in obesity-resistant mice promoted weight gain, while hepatic GK knockdown in obesity-prone mice attenuated weight gain with increased adaptive thermogenesis. Thus, this intertissue energy-saving system may contribute to determining obesity predisposition.

A case of slowly progressive type 1 diabetes with insulin independence maintained for 10 years with α-glucosidase inhibitor monotherapy.

Slowly Progressive Type 1 Diabetes (SPT1D) is characterized by the absence of insulin dependence at the onset of diabetes and persistent detection of islet cell autoantibodies. These patients with high titers of glutamic acid decarboxylase autoantibodies (GADA) are known to progress to insulin dependence within several years. Low-dose insulin injections have been reported to prevent or delay the decline of insulin secretion in SPT1D patients. We experienced the case of an SPT1D patient with preserved endogenous insulin secretion and good glycemic control achieved with α-glucosidase inhibitor (α-GI) treatment alone for 10 years despite having continuously elevated GADA titers. The details of this case suggest that α-GI treatment might have preventive effects on SPT1D progression.

Atf6α-null mice are glucose intolerant due to pancreatic ß-cell failure on a high-fat diet but partially resistant to diet-induced insulin resistance.

Activating transcription factor 6α (ATF6α) is essential for the endoplasmic reticulum (ER) stress response. Since recent studies suggested that ER stress is involved in the pathogenesis of type 2 diabetes mellitus, we have analyzed Atf6α-null (Atf6α(-/-)) mice challenged with metabolic overload or genetic manipulations. Atf6α(-/-) mice were fed a high-fat diet to create diet-induced obese (DO) mice, and were subjected to examination of glucose homeostasis with biochemical and morphological analysis of the pancreatic ß-cell and liver tissues. Atf6α-null mice were also crossed with genetic models of diabetes caused either by insulin resistance (Agouti obese mice) or by impaired insulin secretion (Ins2(WT/C96Y) mice). Atf6α(-/-) DO mice were less glucose tolerant with blunted insulin secretion compared to littermates on a high-fat diet. Pancreatic insulin content was lower in Atf6α(-/-) DO mice with the swollen ß-cell ER, a typical feature of cells with ER stress. In the liver of Atf6α(-/-) DO mice, XBP-1 splicing was increased, suggesting that higher ER stress was present. ATF6-deficient mice showed increased mRNA expressions of glucose-6-phosphatase and SREBP1c associated with a tendency for a higher degree of steatosis in the liver. However, Atf6α(-/-) DO mice exhibited higher insulin sensitivity with lower serum triglyceride levels. Similar phenotypes were observed in ATF6α-deficient Agouti mice. In addition, ATF6α-deficiency accelerated reduction in pancreatic insulin content in Ins2(WT/C96Y) mice. These data suggested that ATF6α contributes to both prevention and promotion of diabetes; it protects ß-cells from ER stress and suppresses hepatosteatosis, but plays a role in the development of hyperlipidemia and insulin resistance.

Blockade of the nuclear factor-κB pathway in the endothelium prevents insulin resistance and prolongs life spans.

BACKGROUND: Nuclear factor-κB (NF-κB) signaling plays critical roles in physiological and pathological processes such as responses to inflammation and oxidative stress. METHODS AND RESULTS: To examine the role of endothelial NF-κB signaling in vivo, we generated transgenic mice expressing dominant-negative IκB under the Tie2 promoter/enhancer (E-DNIκB mice). These mice exhibited functional inhibition of NF-κB signaling specifically in endothelial cells. Although E-DNIκB mice displayed no overt phenotypic changes when young and lean, they were protected from the development of insulin resistance associated with obesity, whether diet- or genetics-induced. Obesity-induced macrophage infiltration into adipose tissue and plasma oxidative stress markers were decreased and blood flow and mitochondrial content in muscle and active-phase locomotor activity were increased in E-DNIκB mice. In addition to inhibition of obesity-related metabolic deteriorations, blockade of endothelial NF-κB signaling prevented age-related insulin resistance and vascular senescence and, notably, prolonged life span. These antiaging phenotypes were also associated with decreased oxidative stress markers, increased muscle blood flow, enhanced active-phase locomotor activity, and aortic upregulation of mitochondrial sirtuin-related proteins. CONCLUSIONS: The endothelium plays important roles in obesity- and age-related disorders through intracellular NF-κB signaling, thereby ultimately affecting life span. Endothelial NF-κB signaling is a potential target for treating the metabolic syndrome and for antiaging strategies.

LST8 level controls basal p70 S6 kinase and Akt phosphorylations, and mTORC1 and mTORC2 negatively regulate each other by competing for association with LST8.

SUMMARY: LST8 is a component of both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Herein, to examine the role of LST8, a common component of mTOR complexes, in the regulation of mTORC1 and mTORC2, first, we showed over-expression of LST8 in HepG2 to markedly enhance basal phosphorylation levels of not only p70 S6 kinase but also Akt. In contrast, LST8 knockdown by siRNA in HepG2 decreased phosphorylation levels of both p70 S6 kinase and Akt. These results indicate the LST8 expression level to determine basal mTORC1 and mTORC2 activities, since LST8 appears to be the component present at the lowest level in both mTORC1 and mTORC2 complexes. Previously, we reported S6 kinase phosphorylation to be reduced by over-expression of the Cterminally deleted Raptor mutant (Raptor-ΔCT) not binding to mTOR or LST8, while phosphorylation levels of Akt were markedly enhanced with no alteration in IRS-1 phosphorylation or PI 3-kinase activity. Using Raptor-ΔCT, we investigated the competition for association with LST8 between mTORC1 and mTORC2. Over-expression of Raptor-ΔCT abolished formation of the Raptor, S6 kinase, mTOR and LST8 complex, while the amount of LST8 in the Rictor-mTOR complex was increased. Therefore, it is likely that Raptor-mTOR and Rictor-mTOR complexes compete for association with LST8, and this mechanism may contribute to the reciprocal negative regulations of mTORC1 and mTORC2 activities, in terms of their LST8 components.:

Hepatic peroxisome proliferator-activated receptor-γ-fat-specific protein 27 pathway contributes to obesity-related hypertension via afferent vagal signals.

AIMS: Obesity is commonly associated with hypertension. Increased sympathetic tonus in obese subjects contributes to the underlying mechanism. However, the precise mechanisms whereby obesity induces this sympathetic activation remain unclear. Hepatic peroxisome proliferator-activated receptor (PPAR)-γ2 expression, which is reportedly upregulated during obesity development, affects sympathetic activation via hepatic vagal afferents. Herein, we report involvement of this neuronal relay in obesity-related hypertension. METHODS AND RESULTS: Peroxisome proliferator-activated receptor-γ and a direct PPARγ target, fat-specific protein 27 (Fsp27), were adenovirally overexpressed or knocked down in the liver, in combination with surgical dissection or pharmacological deafferentation of the hepatic vagus. Adenoviral PPARγ2 expression in the liver raised blood pressure (BP) in wild-type but not in ß1/ß2/ß3 adrenergic receptor-deficient mice. In addition, knockdown of endogenous PPARγ in the liver lowered BP in murine obesity models. Either surgical dissection or pharmacological deafferentation of the hepatic vagus markedly blunted BP elevation in mice with diet-induced and genetically-induced obesity. In contrast, BP was not elevated in other models of hepatic steatosis, DGAT1 and DGAT2 overexpressions, in which PPARγ is not upregulated in the liver. Thus, hepatic PPARγ upregulation associated with obesity is involved in BP elevation during obesity development. Furthermore, hepatic expression of Fsp27 raised BP and the effect was blocked by hepatic vagotomy. Hepatic Fsp27 is actually upregulated in murine obesity models and its knockdown reversed BP elevation. CONCLUSION: The hepatic PPARγ-Fsp27 pathway plays important roles in the development of obesity-related hypertension via afferent vagal signals from the liver.

Cognitive decline in a patient with anti-glutamic acid decarboxylase autoimmunity; case report.

BACKGROUND: Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for producing γ-aminobutyric acid, and it has been suggested that antibodies against GAD play a role in neurological conditions and type 1 diabetes. However, it is not known whether dementia appears as the sole neurological manifestation associated with anti-GAD antibodies in the central nervous system. CASE PRESENTATION: We describe the clinical, neuropsychological, and neuroradiological findings of a 73-year-old female with cognitive dysfunction and type 1A diabetes. Observation and neuropsychological studies revealed linguistic problems, short-term memory disturbance, and frontal dysfunction. MRI showed no significant lesion except for confluent small T2-hyperintensity areas localized in the left basal ganglia. ¹8F-fluorodeoxy glucose-positron emission tomography (FDG-PET) and ¹²³I-N-isopropyl-p-iodoamphetamine-single photon emission computed tomography (IMP-SPECT) studies showed bifrontal hypometabolism and hypoperfusion. Immunomodulating therapy with intravenous high-dose immunoglobulin resulted in no remission of the cognitive symptoms. CONCLUSIONS: Cognitive dysfunction may develop as an isolated neurological manifestation in association with type 1A diabetes and anti-GAD autoimmunity. A systematic study with extensive neuropsychological assessment is indicated in patients with type 1 diabetes and anti-GAD autoimmunity.

Involvement of endoplasmic stress protein C/EBP homologous protein in arteriosclerosis acceleration with augmented biological stress responses.

BACKGROUND: The processes of arteriosclerosis, including atherosclerosis and vascular remodeling, are affected by interactions among numerous biological pathways such as responses to inflammation, oxidative stress, and endoplasmic reticulum stress. C/EBP homologous protein (CHOP), which is well known to induce cellular apoptosis in response to severe endoplasmic reticulum stress, is reportedly upregulated in plaque lesions. METHODS AND RESULTS: We examined the effects of CHOP deficiency on 2 types of arteriosclerosis: cuff injury-induced neointimal formation and hypercholesterolemia-induced atherosclerosis. Cuff injury-induced neointimal formation was markedly inhibited in CHOP(-/-) mice with suppressed aortic expression of inflammatory factors and smooth muscle cell proliferation-related proteins. A CHOP deficiency also inhibited aortic plaque formation in hypercholesterolemic apolipoprotein E(-/-) mice with suppressed aortic expression of inflammatory factors and oxidative stress markers. Bone marrow transplantation experiments revealed that recipient CHOP deficiency significantly suppressed both cuff injury-induced neointimal formation and hypercholesterolemia-induced atherosclerotic plaque formation to a greater extent than donor CHOP deficiency, suggesting the importance of CHOP in vascular cells for arteriosclerosis progression. Furthermore, in our in vitro experiments, in not only macrophages but also endothelial and smooth muscle cell lines, endoplasmic reticulum stress inducers upregulated inflammation-, adhesion-, or smooth muscle cell proliferation-related proteins, whereas decreased CHOP expression remarkably suppressed endoplasmic reticulum stress-induced upregulation of these proteins. CONCLUSIONS: In addition to the well-known signaling for apoptosis induction, CHOP may play important roles in augmenting potentially pathological biological stress responses. This noncanonical role of CHOP, especially that expressed in vascular cells, may contribute to the progression of vascular remodeling and atherosclerosis.

Frequent loss of genome gap region in 4p16.3 subtelomere in early-onset type 2 diabetes mellitus.

A small portion of Type 2 diabetes mellitus (T2DM) is familial, but the majority occurs as sporadic disease. Although causative genes are found in some rare forms, the genetic basis for sporadic T2DM is largely unknown. We searched for a copy number abnormality in 100 early-onset Japanese T2DM patients (onset age <35 years) by whole-genome screening with a copy number variation BeadChip. Within the 1.3-Mb subtelomeric region on chromosome 4p16.3, we found copy number losses in early-onset T2DM (13 of 100 T2DM versus one of 100 controls). This region surrounds a genome gap, which is rich in multiple low copy repeats. Subsequent region-targeted high-density custom-made oligonucleotide microarray experiments verified the copy number losses and delineated structural changes in the 1.3-Mb region. The results suggested that copy number losses of the genes in the deleted region around the genome gap in 4p16.3 may play significant roles in the etiology of T2DM.

Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 associates with insulin receptor substrate-1 and enhances insulin actions and adipogenesis.

Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (Pin1) is a unique enzyme that associates with the pSer/Thr-Pro motif and catalyzes cis-trans isomerization. We identified Pin1 in the immunoprecipitates of overexpressed IRS-1 with myc and FLAG tags in mouse livers and confirmed the association between IRS-1 and Pin1 by not only overexpression experiments but also endogenously in the mouse liver. The analysis using deletion- and point-mutated Pin1 and IRS-1 constructs revealed the WW domain located in the N terminus of Pin1 and Ser-434 in the SAIN (Shc and IRS-1 NPXY binding) domain of IRS-1 to be involved in their association. Subsequently, we investigated the role of Pin1 in IRS-1 mediation of insulin signaling. The overexpression of Pin1 in HepG2 cells markedly enhanced insulin-induced IRS-1 phosphorylation and its downstream events: phosphatidylinositol 3-kinase binding with IRS-1 and Akt phosphorylation. In contrast, the treatment of HepG2 cells with Pin1 siRNA or the Pin1 inhibitor Juglone suppressed these events. In good agreement with these in vitro data, Pin1 knock-out mice exhibited impaired insulin signaling with glucose intolerance, whereas adenoviral gene transfer of Pin1 into the ob/ob mouse liver mostly normalized insulin signaling and restored glucose tolerance. In addition, it was also demonstrated that Pin1 plays a critical role in adipose differentiation, making Pin1 knock-out mice resistant to diet-induced obesity. Importantly, Pin1 expression was shown to be up-regulated in accordance with nutrient conditions such as food intake or a high-fat diet. Taken together, these observations indicate that Pin1 binds to IRS-1 and thereby markedly enhances insulin action, essential for adipogenesis.