Mixed-Lineage Leukaemia Gene Regulates Glucose-Sensitive Gene Expression and Insulin Secretion in Pancreatic Beta Cells.

The escalating prevalence of diabetes mellitus underscores the need for a comprehensive understanding of pancreatic beta cell function. Interest in glucose effectiveness has prompted the exploration of novel regulatory factors. The myeloid/lymphoid or mixed-lineage leukaemia gene (MLL) is widely recognised for its role in leukemogenesis and nuclear regulatory mechanisms through its histone methyltransferase activity in active chromatin. However, its function within pancreatic endocrine tissues remains elusive. Herein, we unveil a novel role of MLL in glucose metabolism and insulin secretion. MLL knockdown in ßHC-9 pancreatic beta cells diminished insulin secretion in response to glucose loading, paralleled by the downregulation of the glucose-sensitive genes SLC2a1 and SLC2a2. Similar observations were made in MLL heterozygous knockout mice (MLL+/-), which exhibited impaired glucose tolerance and reduced insulin secretion without morphological anomalies in pancreatic endocrine cells. The reduction in insulin secretion was independent of changes in beta cell mass or insulin granule morphology, suggesting the regulatory role of MLL in glucose-sensitive gene expression. The current results suggest that MLL interacts with circadian-related complexes to modulate the expression of glucose transporter genes, thereby regulating glucose sensing and insulin secretion. Our findings shed light on insulin secretion control, providing potential avenues for therapeutics against diabetes.

A case of insulinoma-induced hypoglycemia managed by Dexcom G4 Platinum.

This report details the case of a 41-year-old woman who was diagnosed with insulinoma. As the patient developed severe life-threatening hypoglycemia, we introduced Dexcom G4 Platinum (DG4P), a modern continuous glucose-monitoring system (CGM). The algorithm of the sensor glucose (SG) values of CGM is based on patients with diabThis report details the case of a 41-year-old woman who was diagnosed with insulinoma. As the patient developed severe life-threatening hypoglycemia, we introduced Dexcom G4 Platinum (DG4P), a modern continuous glucose-monitoring system (CGM). The algorithm of the sensor glucose (SG) values of CGM is based on patients with diabetes; therefore, we evaluated the accuracy of DG4P in this patient. The mean absolute relative differences and absolute differences between SG of DG4P and self-monitoring of blood sugar values were 10.8%±8.3% and 6.8±5.7 mg/dL, respectively, in the hypoglycemic region, which verifies DG4P's accuracy. DG4P was found to be useful for monitoring hypoglycemia not only in patients with diabetes but also in those with insulinoma.etes; therefore, we evaluated the accuracy of DG4P in this patient. The mean absolute relative differences and absolute differences between SG of DG4P and self-monitoring of blood sugar values were 10.8%±8.3% and 6.8±5.7 mg/dL, respectively, in the hypoglycemic region, which verifies DG4P's accuracy. DG4P was found to be useful for monitoring hypoglycemia not only in patients with diabetes but also in those with insulinoma.

Resolvin E3 ameliorates high-fat diet-induced insulin resistance via the phosphatidylinositol-3-kinase/Akt signaling pathway in adipocytes.

Obesity-associated type 2 diabetes mellitus is associated with the development of insulin resistance. Among several metabolites, resolvins that are metabolites of eicosapentaenoic acid have been shown to exert insulin-sensitizing effects; however, the role of resolvin E3 (RvE3) in glucose metabolism has not been studied. In this study, the effect of RvE3 on glucose metabolism in mice with high-fat diet-induced obesity and 3T3L1 adipocytes was studied. C57BL/6 mice fed a high-fat diet were administered RvE3, for which insulin tolerance, oral glucose tolerance tests, and the homeostasis model assessment of insulin resistance, were performed. RvE3 treatment significantly improved insulin sensitivity and glucose tolerance and regulated protein kinase B (Akt) phosphorylation in the adipose tissue. Moreover, RvE3 treatment enhanced the insulin-stimulated glucose transporter 4 (Glut4) translocation, glucose uptake, phosphatidylinositol-3-kinase (PI3K) activity, and Akt phosphorylation in 3T3L1 adipocytes, whereas a PI3K inhibitor inhibited the enhanced insulin-stimulated glucose uptake induced by RvE3. These findings indicate that RvE3 likely improves insulin sensitivity, resulting in the upregulation of glucose uptake in adipocytes by activating the PI3K/Akt signaling pathways. Collectively, the findings of this study show that RvE3 may play a role in glucose homeostasis and could be used as a potential therapeutic target for developing treatments for obesity-associated diabetes.

Superior Mesenteric Artery Syndrome Accompanied by Acute-onset Type 1 Diabetes Complicated with Graves' Disease.

A 35-year-old man experienced general fatigue and could not eat solid food because of nausea and vomiting. His weight abruptly decreased from 49 to 45 kg after 2 weeks. A detailed examination indicated superior mesenteric artery syndrome (SMAS) accompanied by acute-onset type 1 diabetes complicated by Graves' disease, referred to as autoimmune polyglandular syndrome type 3A (APS3A). Although SMAS has a good prognosis, some cases require emergency surgery, especially when complicated by gastric perforation. In our case, APS3A and SMAS developed rapidly and at approximately the same time, resulting in a cycle of mutual exacerbation.

TBC1D8B, a GTPase-activating protein, is a novel apoptosis inducer.

Overexpressed TBC1D8B, a GTPase-activating protein, significantly reduced cultured HCT116 human colon cancer cell number. We tested N-terminal TBC1D8B, which is identical to wild type TBC1D8B from amino acid positions 1 to 427 and possesses a modified sequence from position 428 to 435 (ECGGLFLL) because of the introduction of a premature stop codon at position 436 to narrow down the minimum requirement element. The N-terminal TBC1D8B contains two GRAM domains but not the TBC domain essential for Rab-GTPase activity. The N-terminal TBC1D8B overexpression significantly reduced the cultured HCT116 cell number. When we tested C-terminal TBC1D8B, containing the portion of TBC1D8B absent in the N-terminal TBC1D8B, the cell number reduction was not observed. The N-terminal TBC1D8B overexpression significantly increased the coronin 1B expression and reduced the phosphorylation of serine 51 in eIF2α, respective markers of apoptosis and cell death/survival. Also, caspase 3 and poly ADP-ribose polymerase increased cleavage in suspended cells overexpressing the N-terminal TBC1D8B. Taken together, it is not the TBC domain for Rab-GTPase activity, but amino acids 1 to 435, including the two GRAM domains, that is enough for TBC1D8B to cause spontaneous apoptosis. TBC1D8B could be a potential anticancer therapeutic molecule.

SFPQ associated with a co-activator for PPARγ, HELZ2, regulates key nuclear factors for adipocyte differentiation.

We recently isolated a novel co-activator of peroxisome proliferator-activated receptor γ, helicase with zinc finger 2 (HELZ2). HELZ2 null mice were resistant to diet-induced obesity and NAFFL/NASH, and HELZ2 was phosphorylated at tyrosine residues. In order to find a factor related to HELZ2, we analyzed products co-immunoprecipitated with phosphorylated HELZ2 by mass spectrometry analyses. We identified proline- and glutamine-rich (SFPQ) as a protein associating with tyrosine-phosphorylated HELZ2. The knockdown of SFPQ in 3T3-L1 cells downregulated mRNA levels of transcription factors including Krox20, Cebpß, and Cebpδ: key factors for early-stage adipocyte differentiation. In addition, knockdown of SFPQ inhibited 3T3-L1 cell differentiation to mature adipocytes. These findings demonstrated that SFPQ associating with HELZ2 is an important novel transcriptional regulator of adipocyte differentiation.

Late-onset non-islet cell tumor hypoglycemia: A case report.

BACKGROUND: Hypoglycemia due to non-insulin-producing tumors is referred to as non-islet cell tumor hypoglycemia (NICTH). As NICTH is a rare lesion, the natural course of NICTH is not well understood. We report a case of NICTH that was observed 30 years before the onset of hypoglycemia. CASE SUMMARY: A 50-year-old man was diagnosed with an abnormal right chest shadow during a routine X-ray examination, but no further examination was undertaken because the lesion appeared benign. Thirty years after the tumor discovery, the patient was admitted to the hospital with symptoms of severe hypoglycemia, which was diagnosed as NICTH based on a complete examination. The tumor was resected and found to be a solitary fibrous mass (15.6 cm × 13.7 cm × 10.4 cm); thereafter, the patient's blood glucose levels normalized and he completely recovered. CONCLUSION: NICTH can have an acute onset, even if the tumor has been present and asymptomatic over a long time period.

FAM83G Is a Novel Inducer of Apoptosis.

The family with sequence similarity 83 (FAM83) protein family G (FAM83G) possesses a predicted consensus phosphorylation motif for serine/threonine-protein kinase D1/protein kinase C mu (PKD1/PKCµ) at serine residue 356 (S356). In this study, overexpressed wild-type FAM83G coimmunoprecipitated with PKD1/PKCµ in Chinese hamster ovary (CHO) cells inhibited heat shock protein 27 (HSP27) phosphorylation at S82 and reduced the living cell number. The expression of a FAM83G phosphorylation-resistant mutant (S356A-FAM83G) had no effect on the living cell number or the induction of spontaneous apoptosis. By contrast, the introduction of a synthetic peptide encompassing FAM83G S356 into HCT116 and HepG2 cells decreased HSP27 S15 and S82 phosphorylation and induced spontaneous apoptosis. On the other hand, the introduction of FAM83G phosphorylation-resistant mutant synthesized peptides (S356A-AF-956 and S356A-AG-066) did not reduce the living cell number or induce spontaneous apoptosis. The endogenous expression of HSP27 and FAM83G was apparently greater in HCT116 and HepG2 cells compared with in CHO cells. In various types of lung cancer cell lines, the FAM83G messenger RNA (mRNA) level in non-small lung cancer cells was at a similar level to that in non-cancerous cells. However, the FAM83G mRNA level in the small cell lung cancer cell lines was variable, and the HSP27 mRNA level in FAM83G mRNA-rich types was greater than that in FAM83G mRNA-normal range types. Taken together, these data demonstrate that FAM83G S356 phosphorylation modulates HSP27 phosphorylation and apoptosis regulation and that HSP27 is a counterpart of FAM83G.

Transcriptional Regulation of the Angptl8 Gene by Hepatocyte Nuclear Factor-1 in the Murine Liver.

Brief refeeding times (~60 min) enhanced hepatic Angptl8 expression in fasted mice. We cloned the mouse Angptl8 promoter region to characterise this rapid refeeding-induced increase in hepatic Angptl8 expression. Deletion of the -309/-60 promoter region significantly attenuated basal promoter activity in hepatocytes. A computational motif search revealed a potential binding motif for hepatocyte nuclear factor 1α/1ß (HNF-1α/ß) at -84/-68 bp of the promoter. Mutation of the HNF-1 binding site significantly decreased the promoter activity in hepatocytes, and the promoter carrying the mutated HNF-1 site was not transactivated by co-transfection of HNF-1 in a non-hepatic cell line. Silencing Hnf-1 in hepatoma cells and mouse primary hepatocytes reduced Angptl8 protein levels. Electrophoretic mobility-shift assays confirmed direct binding of Hnf-1 to its Angptl8 promoter binding motif. Hnf-1α expression levels increased after short-term refeeding, paralleling the enhanced in vivo expression of the Angptl8 protein. Chromatin immunoprecipitation (ChIP) confirmed the recruitment of endogenous Hnf-1 to the Angptl8 promoter region. Insulin-treated primary hepatocytes showed increased expression of Angptl8 protein, but knockdown of Hnf-1 completely abolished this enhancement. HNF-1 appears to play essential roles in the rapid refeeding-induced increases in Angptl8 expression. HNF-1α may therefore represent a primary medical target for ANGPTL8-related metabolic abnormalities. The study revealed the transcriptional regulation of the mouse hepatic Angptl8 gene by HNF-1.

Dapagliflozin Inhibits Cell Adhesion to Collagen I and IV and Increases Ectodomain Proteolytic Cleavage of DDR1 by Increasing ADAM10 Activity.

Dapagliflozin, empagliflozin, tofogliflozin, selective inhibitors of sodium-glucose cotransporter 2 (SGLT2), is used clinically to reduce circulation glucose levels in patients with type 2 diabetes mellitus by blocking the reabsorption of glucose by the kidneys. Dapagliflozin is metabolized and inactivated by UGT1A9. Empagliflozin is metabolized and inactivated by UGT1A9 and by other related isoforms UGT2B7, UGT1A3, and UGT1A8. Tofogliflozin is metabolized and inactivated by five different enzymes CYP2C18, CYP3A4, CYP3A5, CYP4A11, and CYP4F3. Dapagliflozin treatment of HCT116 cells, which express SGLT2 but not UGT1A9, results in the loss of cell adhesion, whereas HepG2 cells, which express both SGLT2 and UGT1A9, are resistant to the adhesion-related effects of dapagliflozin. PANC-1 and H1792 cells, which do not express either SGLT2 or UGT1A9, are also resistant to adhesion related effects of dapagliflozin. On the other hand, either empagliflozin or tofogliflozin treatment of HCT116, HepG2, PANC-1, and H1792 cells are resistant to the adhesion-related effects as observed in dapagliflozin treated HCT116 cells. Knockdown of UGT1A9 by shRNA in HepG2 cells increased dapagliflozin sensitivity, whereas the overexpression of UGT1A9 in HCT116 cells protected against dapagliflozin-dependent loos of cell adhesion. Dapagliflozin treatment had no effect on cellular interactions with fibronectin, vitronectin, or laminin, but it induced a loss of interaction with collagen I and IV. In parallel, dapagliflozin treatment reduced protein levels of the full-length discoidin domain receptor I (DDR1), concomitant with appearance of DDR1 cleavage products and ectodomain shedding of DDR1. In line with these observations, unmetabolized dapagliflozin increased ADAM10 activity. Dapagliflozin treatment also significantly reduced Y792 tyrosine phosphorylation of DDR1 leading to decrement of DDR1 function and detachment of cancer cells. Concomitant with these lines of results, we experienced that CEA in patients with colon cancer, which express SGLT2 but not UGT1A9, and type 2 diabetes mellitus treated by dapagliflozin in addition to chemotherapy was decreased (case 1). CEA in patients with colon cancer, which express SGLT2 but not UGT1A9, and type 2 diabetes mellitus was treated by dapagliflozin alone after radiation therapy was decreased but started to rise after cessation of dapagliflozin (case 2). CA19-9 in two of patients with pancreatic cancer and type 2 diabetes mellitus was resistant to the combination therapy of dapagliflozin and chemotherapy (case 3 and 4 respectively). PIVKAII in patients with liver cancer and type 2 diabetes mellitus, and CYFRA in patients with squamous lung cancer and type 2 diabetes mellitus was also resistant the combination therapy of dapagliflozin and chemotherapy (case 5 and 6 respectively). Taken together, these data suggest a potential role for dapagliflozin anticancer therapy against colon cancer cells that express SGLT2, but not UGT1A9.

Regulation of the KCNJ5 gene by SF-1 in the adrenal cortex: Complete genomic organization and promoter function.

Activating mutations in the KCNJ5 gene are responsible for the significant number of aldosterone-producing adenomas. To elucidate the molecular mechanisms underlying KCNJ5 expression, we characterized the entire human KCNJ5 gene. The gene spanned approximately 29.8 kb and contained three exons and two introns. The strongest expression of KCNJ5 mRNA was observed in the adrenal gland. The promoter region contained a putative binding site for SF-1 at -1782 bp. A construct containing -2444 bp of the promoter region exhibited the strongest promoter activity in adrenal H295R cells, and the introduction of a mutation in the SF-1 binding site almost completely abolished promoter activity. Furthermore, deletion mutation, EMSA, and knockdown analyses revealed that SF-1 bound to this element and was functional. Immunochemistry showed that KCNJ5 was predominantly expressed in the zona glomerulosa, while SF-1 was ubiquitously expressed in the adrenal cortex. These results demonstrated that SF-1 mediates the expression of human KCNJ5 in the adrenal cortex.

Influence of Smoking on Thyroid Function in Japanese Subjects: Longitudinal Study for One Year of On-Off Smoking.

CONTEXT: We previously identified factors affecting thyroid status, including sex, age, and smoking. OBJECTIVE: In the current study, we increased the number of subjects examined and investigated the effects of these factors, particularly smoking and the thyroid peroxidase antibody (TPO-Ab), in Japanese patients with euthyroxinemia and serum free T4 levels within the normal range. PARTICIPANTS: A total of 12,289 subjects who underwent health checkups were analyzed in a cross-sectional and longitudinal study. RESULTS: The mean age of subjects was 50 ± 10 years (age range: 21 to 88 years). Serum TSH levels and the prevalence of positivity for TPO-Ab increased with age in Japanese subjects with euthyroxinemia. Mean serum TSH levels were significantly lower in the smoking group than in the nonsmoking group except for women older than 50 years. Serum TSH levels were significantly higher in subjects with positivity for TPO-Ab than in those with negativity at all ages and in both sexes; however, smoking did not affect free T4 levels or positivity for TPO-Ab. Among men, the rate of smokers was significantly higher in patients with subclinical hyperthyroidism (25%) than in those with subclinical hypothyroidism (10%; P < 0.05). Furthermore, the results of the longitudinal study revealed a significant decrease in serum TSH levels 1 year after the start of smoking in men (P < 0.05). CONCLUSION: Because smoking appeared to lower serum TSH levels in Japanese subjects with euthyroxinemia, their smoking status warrants careful consideration when evaluating subclinical thyroid function.

In situ condensation of an anti-cancer drug into fibrin gel enabling effective inhibition of tumor cell growth.

We show herein the highly effective inhibition of tumor cell growth using a gel consisting of a fibrin polymer formed with the in situ condensation of a camptothecin (CPT) derivative as an anti-cancer drug, which is efficiently conveyed with a carrier aptamer from a solution to the gel in a phenomenon, called selective oligonucleotide entrapment in fibrin polymers (SOEF).

Dapagliflozin rescues endoplasmic reticulum stress-mediated cell death.

The new type 2 diabetes drug, dapagliflozin, reduces blood glucose levels and body weight by inhibiting sodium glucose transporter 2 (SGLT2) in proximal tubular cells. SGLT2 inhibitors might modulate glucose influx into renal tubular cells, thereby regulating the metabolic conditions that cause endoplasmic reticulum (ER) stress in the cells. In this study, we examined the effect of dapagliflozin on ER stress in the HK-2 proximal tubular cell line and in the kidney of db/db mice to characterise its function in diabetic nephropathy (DN). We found that dapagliflozin regulated ER stress-mediated apoptosis in vitro and in vivo. Only the elf2α-ATF4-CHOP pathway was regulated under these conditions. Notably, the drug rescued C2 ceramide-induced ER stress-mediated apoptosis and ER stress-mediated apoptosis, which might occur in DN, in db/db mice. Our study shows a novel role for dapagliflozin as an inhibitor of ER stress and suggests that dapagliflozin might be useful for the prevention of DN.

Basal Autophagy Deficiency Causes Thyroid Follicular Epithelial Cell Death in Mice.

Autophagy is a catabolic process that involves the degradation of cellular components through the lysosomal machinery, relocating nutrients from unnecessary processes to more pivotal processes required for survival. It has been reported that systemic disruption of the Atg5 or Atg7 gene, a component of autophagy, is lethal and that its tissue-specific disruption causes tissue degeneration in several organs. However, the functional significance of autophagy in the thyroid glands remains unknown. Our preliminary data imply the possible involvement of dysfunctional autophagy in radiation-induced thyroid carcinogenesis. Therefore, we evaluated the effect of Atg5 gene knockout (KO) on thyroid morphology and function. To this end, Atg5flox/flox mice were crossed with TPO-Cre mice, yielding the thyroid follicular epithelial cell (thyrocyte)‒specific ATG5-deficient mice (Atg5thyr-KO/KO). Atg5 gene KO was confirmed by a lack of ATG5 expression, and disruption of autophagy was demonstrated by a decrease in microtubule-associated protein 1 light chain 3-II puncta and an increase in p62. Atg5thyr-KO/KO mice were born normally, and thyroid morphology, thyroid weights, and serum T4 and TSH levels were almost normal at 4 months. However, at 8 and 12 months, a decrease in the number of thyrocytes and an increase in TUNEL+-thyrocytes were observed in Atg5thyr-KO/KO mice even though thyroid function was still normal. The number of irregularly shaped (gourd-shaped) follicles was also increased. Excess oxidative stress was indicated by increased 8-hydroxy-2'-deoxyguanosine and 53BP1 foci in Atg5thyr-KO/KO mice. These data demonstrate that thyrocytes gradually undergo degradation/cell death in the absence of basal levels of autophagy, indicating that autophagy is critical for the quality control of thyrocytes.

Central Hypothyroidism Related to Pituitary Adenomas: Low Incidence of Central Hypothyroidism in Patients With Acromegaly.

CONTEXT: The most frequent cause of central hypothyroidism (CeH) is pituitary adenomas, but the mechanisms remain unclear. OBJECTIVE: We investigated serum thyroid levels and GH/IGF-1 in central hypothyroidism in untreated patients with pituitary nonfunctioning and GH-secreting adenomas. DESIGN: This was a retrospective cross-sectional study of cases collected from Gunma University and Toranomon Hospitals between 2007 and 2016. PATIENTS: One-hundred thirty-nine cases of nonfunctioning pituitary adenoma (NFPA) and 150 cases of GH-secreting pituitary adenoma (GHPA) were analyzed. MAIN OUTCOME MEASURES: The correlations between thyroid levels, several clinicopathological parameters, and GH/IGF-1 were examined. RESULTS: Twenty-four percent of NFPA patients had CeH. The severity did not correlate with tumor size, age, or sex, and all cases had normal TSH levels. In contrast, only 8.7% of GHPA patients had CeH; approximately half had normal TSH levels and approximately half had low TSH levels. Serum TSH levels in GHPA patients were significantly lower and free T4 (FT4) and free T3 levels were higher than those in patients with NFPA. Furthermore, approximately one-fourth of GHPA patients had normal FT4 and low TSH levels. In addition, serum FT4 levels and serum TSH levels were positively and negatively correlated, respectively, with serum IGF-1 levels. Furthermore, IGF-1 levels in patients with GHPA decreased with age. CONCLUSIONS: (i) NFPA patients with CeH had TSH levels within a normal range. (ii) GHPA patients had a low incidence of CeH, which may be a result of stimulated thyroid function by GH/IGF-1. (iii) We found an age-dependent decrease in serum IGF-1 levels in patients with GHPA.

Age-Dependent Progression of Renal Dysfunction After Adrenalectomy for Aldosterone-Producing Adenomas in Japan.

CONTEXT: In patients with aldosterone-producing adenomas (APAs), adrenalectomy causes a rapid decrease in blood pressure and increase in blood potassium levels; however, the effects of these intensive metabolic changes on kidney function with age have not yet been examined in Japan. OBJECTIVE: To investigate factors related to the progression of kidney dysfunction after adrenalectomy in different age groups. PARTICIPANTS: Fifty Japanese patients with APAs and 27,572 health checkup patients as controls were examined. MAIN OUTCOME MEASURES: We investigated changes in estimated glomerular filtration rate (eGFR) after adrenalectomy and characterized patients who progressed to chronic kidney disease (CKD). RESULTS: The postoperative cutoff age of CKD is 50 years and age is a unique factor for the progression of CKD after adrenalectomy. Among preoperative patients, CKD was 6% for those <50 years old and 40% for those ≥50 years old, indicating a higher prevalence of CKD with APAs than in control subjects. Median eGFR <50 mL/min/1.73 m2 did not significantly change after adrenalectomy but decreased from 67 to 42 mL/min/1.73 m2 in those with APAs ≥50 years old. Patients with APAs ≥50 years old who progressed to CKD showed higher preoperative aldosterone/renin ratios, lower potassium and chloride levels, lower body mass index, and a higher incidence of a history of cardiovascular events and KCNJ5 mutation rates. CONCLUSION: Age is the most important predictor of the progression of kidney dysfunction after adrenalectomy in Japanese patients with APAs, particularly those with a history of cardiovascular events and positivity for KCNJ5 mutations.

Transducin ß-like 1, X-linked and nuclear receptor co-repressor cooperatively augment the ligand-independent stimulation of TRH and TSHß gene promoters by thyroid hormone receptors.

Mutations in TBL1X, a component of the nuclear receptor co-repressor (N-CoR) and silencing mediator of retinoic acid and thyroid hormone receptor co-repressor complexes, have recently been implicated in isolated central hypothyroidism (CeH). However, the mechanisms by which TBL1X mutations affect negative feedback regulation in the hypothalamus-pituitary-thyroid axis remain unclear. N-CoR was previously reported to paradoxically enhance the ligand-independent stimulation of TRH and TSHß gene promoters by thyroid hormone receptors (TR) in cell culture systems. We herein investigated whether TBL1X affects the unliganded TR-mediated stimulation of the promoter activities of genes negatively regulated by T3 in cooperation with N-CoR. In a hypothalamic neuronal cell line, the unliganded TR-mediated stimulation of the TRH gene promoter was significantly enhanced by co-transfected TBL1X, and the co-transfection of TBL1X with N-CoR further enhanced promoter activity. In contrast, the knockdown of endogenous Tbl1x using short interfering RNA significantly attenuated the N-CoR-mediated enhancement of promoter activity in the presence of unliganded TR. The co-transfection of N365Y or Y458C, TBL1X mutants identified in CeH patients, showed impaired co-activation with N-CoR for the ligand-independent stimulation of the TRH promoter by TR. In the absence of T3, similar or impaired enhancement of the TSHß gene promoter by the wild type or TBL1X mutants, respectively, was observed in the presence of co-transfected TR and N-CoR in CV-1 cells. These results suggest that TBL1X is needed for the full activation of TRH and TSHß gene promoters by unliganded TR. Mutations in TBL1X may cause CeH due to the impaired up-regulation of TRH and/or TSHß gene transcription despite low T3 levels.

Continuous or Transient High Level of Glucose Exposure Differentially Increases Coronary Artery Endothelial Cell Proliferation and Human Colon Cancer Cell Proliferation.

We studied effect of high glucose levels on coronary artery endothelial cell proliferation and human colon cancer cell proliferation. To examine the long-term effect of glucose exposure on cell growth, cells were cultured for 14 days in the absence or presence of 183 mg/dL D-glucose addition in the culture medium. Short effect of elevated glucose levels was examined by addition of 183 mg/dL D-glucose addition in the culture medium for just one hour per day followed by changing the culture to standard medium (5.5 mM D-glucose) during the next 23-hours period. Cell proliferation was estimated by 2,3-Bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carbox-anilide (XTT) assay and phosphor-Erk western blot analysis. We found that coronary artery endothelial cell proliferation was significantly increased in the culture medium with the acute one-hour addition of 183 mg/dL D-glucose compared to the absence or chronic presence of 183 mg/dL D-glucose addition in the culture medium. In contrast, colon cancer cell proliferation was significantly increased in the continuous presence of 183 mg/dL D-glucose addition in the culture medium compared to the acute one-hour addition of glucose. The extent of Erk2 phosphorylation paralleled with the relative changes in cellular proliferation in both cell types. Taken together, these results suggested that continuous or transient high level of glucose exposure differentially effects coronary artery endothelial and human colon cancer cell proliferation.

Characteristics of Japanese aldosterone-producing adenomas with KCNJ5 mutations.

Somatic mutations in KCNJ5 gene have been identified in patients with adrenal aldosterone-producing adenomas (APAs). We previously reported that Japanese patients with APAs had distinct characteristics from patients in Western countries; i.e. they had a high frequency of KCNJ5 mutations and exhibited a frequent association with cortisol co-secretion. Therefore, APAs among Japanese patients may have different features from those in Western countries. We added recent cases, examined 47 cases (43% male) of APAs, including clinicopathological features, KCNJ5 mutations, and the mRNA levels of several steroidogenic enzymes, and compared the results obtained to those reported in other countries. While the prevalence of KCNJ5 mutations is approximately 40% in Western countries, 37 APA cases (78.7%) showed mutations: 26 with p.G151R and 11 with p.L168R. Although a significant gender difference has been reported in the frequency of KCNJ5 mutations in Europe, we did not find any gender difference. However, the phenotypes of Japanese patients with mutations were similar to those of patients in Western countries; patients were younger and had higher plasma aldosterone levels, lower potassium levels, and higher diastolic blood pressure. Reflecting these phenotypes, APAs with mutations had higher CYP11B2 mRNA levels. However, in contrast to APAs in Western countries, Japanese APAs with mutations showed lower CYP11B1, CYP17A1, and CYP11A1 mRNA levels. These findings demonstrated that Japanese APA patients may have distinct features including a higher prevalence of KCNJ5 mutations, no gender difference in the frequency of these mutations, and characteristics similar to the zona glomerulosa.