An intronic SNP in the thyroid hormone receptor β gene is associated with pituitary cell-specific over-expression of a mutant thyroid hormone receptor β2 (R338W) in the index case of pituitary-selective resistance to thyroid hormone

<p>Abstract</p> <p>Background</p> <p>The syndrome of resistance to thyroid hormone (RTH) is caused by mutations in the thyroid hormone receptor β gene (<it>THRB</it>). The syndrome varies from asymptomatic to diffuse hypothyroidism, to pituitary-selective resistance with predominance of hyperthyroid signs and symptoms. The wide spectrum of clinical presentation is not completely attributable to specific <it>THRB </it>mutations. The <it>THRB </it>gene encodes two main isoforms, TR β1 which is widely distributed, and TR β2, whose expression is limited to the cochlea, retina, hypothalamus, and pituitary. Recent data demonstrated that in mice an intron enhancer region plays a critical role in the pituitary expression of the β2 isoform of the receptor. We thus hypothesized that polymorphisms in the human homologous region could modulate the pituitary expression of the mutated gene contributing to the clinical presentation of RTH.</p> <p>Methods</p> <p>Screening and <it>in vitro </it>characterization of polymorphisms of the intron enhancer region of the <it>THRB </it>gene in the index case of pituitary-selective RTH.</p> <p>Results</p> <p>The index case of pituitary-selective resistance is characterized by the missense R338W exon 9 mutation in <it>cis </it>with two common SNPs, rs2596623T and rs2596622C, located in the intron enhancer region of the <it>THRB </it>gene. Reporter gene assay experiments in GH3 pituitary-derived cells indicate that rs2596623T generates an increased pituitary cell-specific activity of the TR β2 promoter suggesting that rs2596623T leads to pituitary over-expression of the mutant allele.</p> <p>Conclusions</p> <p>The combined coding mutation and non-coding SNP therefore generate a tissue-specific dominant-negative condition recapitulating the patient's peculiar phenotype. This case illustrates the role of regulatory regions in modifying the clinical presentation of genetic diseases.</p

Lipids and insulin regulate mitochondrial-derived peptide (MOTS-c) in PCOS and healthy subjects

Objective: Polycystic ovarian syndrome (PCOS) is a heterogeneous endocrine disorder associated with mitochondrial dysfunction and insulin resistance (IR). MOTS-c, a mitochondrial peptide, promotes insulin sensitivity (IS) through activating AKT and AMPK-dependent pathways. The current study was designed to examine the response of MOTS-c to lipids (intralipid) followed by insulin in PCOS and healthy subjects. Methods: All subjects underwent 5-hour intralipid/saline infusion with a hyperinsulinemic-euglycaemic clamp in the final 2 hours. Plasma samples were collected to measure circulating MOTS-c using a commercial ELISA kit. Subsequently, this was repeated following an eight-week exercise intervention. Results: Intralipid significantly increased plasma MOTS-c both in controls and PCOS subjects, whilst the insulin infusion blunted the intralipid-induced response seen for both lipids and MOT-c. Intralipid elevated plasma MOTS-c to 232±124% of basal in control (P < 0.01) and to 349 ± 206% of basal in PCOS (P < 0.001) subjects. Administration of insulin suppressed intralipid-induced MOTS-c from 232 ± 124% to 165 ± 97% (NS) in control and from 349 ± 206% to 183 ± 177% (P < 0.05) in PCOS subjects, respectively. Following exercise, intralipid elevated plasma MOTS-c to 305 ± 153% of basal in control (P < 0.01) and to 215 ± 103% of basal in PCOS (P < 0.01) subjects; insulin suppressed intralipid-induced MOTS-c only in controls.ConclusionsIn conclusion, this is the first study to show increased lipid enhanced circulating MOTS-c whilst insulin attenuated the MOTS-c response in human. Further, eight weeks of moderate exercise training did not show any changes in circulating MOTS-c levels in healthy controls and in women with PCOS

Dynamic Changes in Circulating Endocrine FGF19 Subfamily and Fetuin-A in Response to Intralipid and Insulin Infusions in Healthy and PCOS Women

© Copyright © 2020 Ramanjaneya, Bensila, Bettahi, Jerobin, Samra, Aye, Alkasem, Siveen, Sathyapalan, Skarulis, Atkin and Abou-Samra. Background: The fibroblast growth factors (FGF) 19 subfamily, also referred to as endocrine FGFs, includes FGF19, FGF21, and FGF23 are metabolic hormones involved in the regulation of glucose and lipid metabolism. Fetuin-A is a hepatokine involved in the regulation of beta-cell function and insulin resistance. Endocrine FGFs and fetuin-A are dysregulated in metabolic disorders including obesity, type 2 diabetes, non-alcoholic fatty liver disease and polycystic ovary syndrome (PCOS). Our study was designed to examine the response of endocrine FGFs and fetuin-A to an acute intralipid, insulin infusion and exercise in PCOS and healthy women. Subjects and Measurements: Ten healthy and 11 PCOS subjects underwent 5-h saline infusions with a hyperinsulinemic-euglycemic clamp (HIEC) performed during the final 2 h. One week later, intralipid infusions were undertaken with a HIEC performed during the final 2 h. After an 8 week of exercise intervention the saline, intralipid, and HIEC were repeated. Plasma levels of endocrine FGFs and fetuin-A were measured. Results: Baseline fetuin-A was higher in PCOS women but FGF19, FGF21, and FGF23 did not differ and were unaffected by exercise. Insulin administration elevated FGF21 in control and PCOS, suppressed FGF19 in controls, and had no effects on FGF23 and fetuin-A. Intralipid infusion suppressed FGF19 and increased FGF21. Insulin with intralipid synergistically increased FGF21 and did not have effects on lipid-mediated suppression of FGF19 in both groups. Conclusion: Our study provides evidence for insulin and lipid regulation of endocrine FGFs in healthy and PCOS women, suggesting that FGF family members play a role in lipid and glucose metabolism. Clinical Trial Registration: www.isrctn.org, Identifier: ISRCTN42448814

Mitochondrial-Derived Peptides Are Down Regulated in Diabetes Subjects

Background: Mitochondrial dysfunction is implicated in the pathogenesis of Type 2 diabetes (T2D) and the development of diabetes related complications such as cardiovascular disease and stroke. Mitochondria produce several small polypeptides that may influence mitochondrial function and may impact on insulin sensitivity, such as humanin (HN) and the mitochondrial open reading frame of the 12S rRNA type-c (MOTS-c) that are mitochondrial derived proteins (MDP). The aim of this study was to determine MDP in normal, prediabetes and diabetes subjects.Subjects and Measurements: In this cross-sectional study, we analyzed the serum concentrations of MDP and adiponectin (ADP) in 225 subjects: normal (n = 68), pre-diabetes (n = 33), T2D less than (good control; n = 31), and greater than HbA1c 7% (poor control; n = 93) subjects. The relationship of serum MDP and ADP concentrations with biochemical and anthropometric measurements were performed and assessed by multilinear regression.Results: Serum HN concentrations were lower in T2D (p &lt; 0.0001) and negatively correlated with age (p &lt; 0.0001), HbA1c (p &lt; 0.0001), glucose (p &lt; 0.0001), triglycerides (p &lt; 0.003), ALT (p &lt; 0.004), and TG/HDL ratio (p &lt; 0.001). Circulating HN levels were positively correlated to cholesterol (p &lt; 0.017), LDL (p &lt; 0.001), and HDL (p &lt; 0.001). Linear regression analysis showed that HbA1c and ALT were two independent predictors of circulating HN. Similarly, serum MOTS-c was significantly lower in T2D subjects compared to controls (p &lt; 0.007). Circulating MOTS-c positively correlated with BMI (p &lt; 0.035), total cholesterol (p &lt; 0.0001), and LDL (p &lt; 0.001) and negatively correlated with age (p &lt; 0.002), HbA1c (p &lt; 0.001), and glucose (p &lt; 0.002). Serum ADP concentrations were lower in T2D (p &lt; 0.002) and negatively correlated with HbA1c (p &lt; 0.001), weight (p &lt; 0.032) TG (p &lt; 0.0001), and ALT (p &lt; 0.0001); and positively correlated with HDL (p &lt; 0.0001) and HN (p &lt; 0.003). Linear regression analysis showed that HbA1c and weight were two independent predictors of circulating ADP. Multilinear regression showed that HN and MOT-c correlated with each other, and only HN correlated with HbA1c.Conclusion: The MDPs HN and MOT-c, similar to ADP, are decreased in T2D and correlate with HbA1c. The data provide an additional evidence that mitochondrial dysfunction contributes to glycemic dysregulation and metabolic defects in T2D

Prognosis of Differentiated Thyroid Cancer in Relation to Serum Thyrotropin and Thyroglobulin Antibody Status at Time of Diagnosis

BACKGROUND: Serum thyrotropin (TSH) concentration and thyroid autoimmunity may be of prognostic importance in differentiated thyroid cancer (DTC). Preoperative serum TSH level has been associated with higher DTC stage in cross-sectional studies; data are contradictory on the significance of thyroid autoimmunity at the time of diagnosis. OBJECTIVE: We sought to assess whether preoperative serum TSH and perioperative antithyroglobulin antibodies (TgAb) were associated with thyroid cancer stage and outcome in DTC patients followed by the National Thyroid Cancer Treatment Cooperative Study, a large multicenter thyroid cancer registry. METHODS: Patients registered after 1996 with available preoperative serum TSH (n=617; the TSH cohort) or perioperative TgAb status (n=1770; the TgAb cohort) were analyzed for tumor stage, persistent disease, recurrence, and overall survival (OS; median follow-up, 5.5 years). Parametric tests assessed log-transformed TSH, and categorical variables were tested with chi square. Disease-free survival (DFS) and OS was assessed with Cox models. RESULTS: Geometric mean serum TSH levels were higher in patients with higher-stage disease (Stage III/IV=1.48 vs. 1.02 mU/L for Stages I/II; p=0.006). The relationship persisted in those aged ≥45 years after adjusting for sex (p=0.01). Gross extrathyroidal extension (p=0.03) and presence of cervical lymph node metastases (p=0.003) were also significantly associated with higher serum TSH. Disease recurrence and all-cause mortality occurred in 37 and 38 TSH cohort patients respectively, which limited the power for survival analysis. Positive TgAb was associated with lower stage on univariate analysis (positive TgAb in 23.4% vs. 17.8% of Stage I/II vs. III/IV patients, respectively; p=0.01), although the relationship lost significance when adjusting for age and sex (p=0.34). Perioperative TgAb was not an independent predictor of DFS (hazard ratio=1.12 [95% confidence interval=0.74-1.69]) or OS (hazard ratio=0.98 [95% confidence interval=0.56-1.72]). CONCLUSIONS: Preoperative serum TSH level is associated with higher DTC stage, gross extrathyroidal extension, and neck node metastases. Perioperative TgAb is not an independent predictor of DTC prognosis. A larger cohort is required to assess whether preoperative serum TSH level predicts recurrence or mortality

Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity

© 2015 Elsevier Inc. Dietary carbohydrate restriction has been purported to cause endocrine adaptations that promote body fat loss more than dietary fat restriction. We selectively restricted dietary carbohydrate versus fat for 6 days following a 5-day baseline diet in 19 adults with obesity confined to a metabolic ward where they exercised daily. Subjects received both isocaloric diets in random order during each of two inpatient stays. Body fat loss was calculated as the difference between daily fat intake and net fat oxidation measured while residing in a metabolic chamber. Whereas carbohydrate restriction led to sustained increases in fat oxidation and loss of 53 ± 6 g/day of body fat, fat oxidation was unchanged by fat restriction, leading to 89 ± 6 g/day of fat loss, and was significantly greater than carbohydrate restriction (p = 0.002). Mathematical model simulations agreed with these data, but predicted that the body acts to minimize body fat differences with prolonged isocaloric diets varying in carbohydrate and fat

Impaired Tethering and Fusion of GLUT4 Vesicles in Insulin-Resistant Human Adipose Cells

Systemic glucose homeostasis is profoundly influenced by adipose cell function. Here we investigated GLUT4 dynamics in living adipose cells from human subjects with varying BMI and insulin sensitivity index (S-i) values. Cells were transfected with hemagglutinin (HA)-GLUT4-green fluorescent protein (GFP)/mCherry (red fluorescence), and were imaged live using total internal reflection fluorescence and confocal microscopy. HA-GLUT4-GFP redistribution to the plasma membrane (PM) was quantified by surface-exposed HA epitope. In the basal state, GLUT4 storage vesicle (GSV) trafficking to and fusion with the PM were invariant with donor subject S-i, as was total cell-surface GLUT4. In cells from insulin-sensitive subjects, insulin augmented GSV tethering and fusion approximately threefold, resulting in a corresponding increase in total PM GLUT4. However, with decreasing S-i, these effects diminished progressively. All insulin-induced effects on GLUT4 redistribution and trafficking correlated strongly with S-i and only weakly with BMI. Thus, while basal GLUT4 dynamics and total cell-surface GLUT4 are intact in human adipose cells, independent of donor S-i, cells from insulin-resistant donors show markedly impaired GSV tethering and fusion responses to insulin, even after overnight culture. This altered insulin responsiveness is consistent with the hypothesis that adipose cellular dysfunction is a primary contributor to systemic metabolic dysfunction