Steroid hormones are synthesized from cholesterol in various tissues, mainly in the adrenal glands and gonads. Because these lipid-soluble steroid hormones immediately diffuse through the cells in which they are produced, their secretion directly reflects the activity of the genes related to their production. Progesterone is important not only for luteinization and maintenance of pregnancy, but also as a substrate for most other steroids. Steroidogenic acute regulatory protein (STAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3β-HSD) are well-known proteins essential for progesterone production. In addition to them, glutathione S-transferase A1-1 and A3-3 are shown to exert Δ5-Δ4 isomerization activity to produce progesterone in a cooperative fashion with 3β-HSD. 5-Aminolevulinic acid synthase 1, ferredoxin 1, and ferredoxin reductase also play a role in steroidogenesis as accessory factors. Members of the nuclear receptor 5A (NR5A) family (steroidogenic factor 1 and liver receptor homolog 1) play a crucial role in the transcriptional regulation of these genes. The NR5A family activates these genes by binding to NR5A responsive elements present within their promoter regions, as well as to the elements far from their promoters. In addition, various NR5A-interacting proteins including peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), nuclear receptor subfamily 0, group B, member 1 (DAX-1), and CCAAT/enhancer-binding proteins (C/EBP) are involved in the transcription of NR5A target genes and regulate the transcription either positively or negatively under both basal and tropic hormone-stimulated conditions. In this review, we describe the transcriptional regulation of genes related to progesterone production.
In the adrenal, the type I 3β-hydroxysteroid dehydrogenase (HSD3B1) is expressed exclusively in the zona glomerulosa (ZG), where aldosterone is produced. Angiotensin II (AngII) and potassium (K+) are the major physiological regulators of aldosterone synthesis. However, their respective roles in regulation of aldosterone synthesis are not fully defined, particularly in terms of transcriptional regulation of steroidogenic enzyme genes. We previously showed that AngII can stimulate expression of HSD3B1. But, K+ responsiveness of this gene has remained unexplored. Here, we report that K+ stimulation lacks the ability to induce HSD3B1 expression in human adrenocortical H295R cells. Both AngII and K+ were able to enhance transcription of the aldosterone synthase gene (CYP11B2). Promoter analysis revealed that although both AngII and K+ activate transcription from the Ca2+/cAMP-responsive element (CRE) located in the CYP11B2 promoter, the orphan nuclear receptor NGFIB-responsive element (NBRE) located in the HSD3B1 promoter fails to respond to K+, being only able to enhance transcription after AngII treatment. We found that induction of de novo protein synthesis of NGFIB occurs only after AngII treatment. This sharply contrasts with the phosphorylation that occurs in response to both AngII and K+ on the CREB/ATF family transcription factor ATF2. Chromatin immunoprecipitation assay confirmed that the NGFIB protein occupies the HSD3B1 promoter only after AngII, while ATF2 binds to the CYP11B2 promoter in response to both AngII and K+. These data provide evidence that downstream signals from AngII and K+ can be uncoupled in the regulation of HSD3B1 in the human adrenocortical H295R cells.
Clarifying the relationship of sex hormones to preclinical atherosclerosis could illuminate pathways by which androgens are associated with cardiovascular events and mortality. Our aim was to determine hormone profiles associated with carotid intima-media thickness (CIMT) and carotid atheroma, in men with and without known coronary artery disease (CAD). We included 492 community-based men aged 20-70 years (Group A) and 426 men with angiographically proven CAD aged <60 years (Group B). Fasting early morning sera were assayed for testosterone (T), dihydrotestosterone (DHT) and estradiol (E2) using mass spectrometry. CIMT and carotid plaque were assessed ultrasonographically. Mean (±SD) age was Group A: 53.8±12.6 and Group B: 49.6±5.1 years. Higher T was associated with reduced CIMT (-0.011 mm per 1-SD increase, p=0.042) and lower prevalence of carotid plaque (odds ratio [OR] per 1-SD increase, 0.68, p=0.012) in Group A, but not B. E2 was associated with increased CIMT in Group A (0.013 mm, p=0.011) but not B. Higher DHT and E2 were associated with reduced carotid plaque in Group B (DHT: OR=0.77, p=0.024; E2: OR=0.75, p=0.008), but not A. In community-dwelling men, higher T is associated with favourable CIMT and lower prevalence of carotid plaque, while higher E2 is associated with worse CIMT. In men with CAD, higher DHT or E2 are associated with less carotid plaque. T, DHT and E2 are differentially associated with preclinical carotid atherosclerosis in a cardiovascular phenotype-specific manner. Interventional studies are needed to examine effects of exogenous T and its metabolites DHT and E2, on atherogenesis.
Type 2 diabetes mellitus (T2DM) is one of the major health concern among the world. Several treatment options for T2DM are in clinical use, including injecting insulin, promoting insulin secretion by insulin secretagogues, and improving insulin sensitivity by insulin sensitizers. However, increasing the amount of insulin receptor in insulin-target tissues has not been explored. In order to test the efficacy of insulin receptor overexpression for improving glucose control, we established a transgenic mouse line expressing human insulin receptor (INSR). We analyzed, growth, energy balance, and glucose control of INSR-overexpressing db/db mice (INSR; db/db), which we produced by mating INSR transgenic mice with db/db mice, a genetic model of obesity due to insufficient leptin signaling. Compared to db/db mice, INSR; db/db mice were rescued from hyperphagia and obesity, leading to improved blood glucose levels. Unexpectedly, however, INSR; db/db mice presented with stunted growth, accompanied by decreased plasma levels of free IGF1 and IGFBP-3, indicating the down-regulation of GH/IGF1 axis. These phenotypes were observed in INSR; db/db mice but not in INSR littermates. Meanwhile, bone defects observed in db/db male mice were not rescued. Moreover, improved blood glucose was not accompanied by improved insulin sensitivity. Therefore, overexpression of insulin receptor improves obese and diabetic phenotypes in db/db mice, with consequences on growth.
Chromogranin A (CHGA) is a major protein in the secretory granules of chromaffin cells. CHGA also gives rise to cardiovascular/metabolism regulatory peptides, such as catestatin (CST) and pancreastatin (PST). While CST is a potent inhibitor of catecholamine secretion, PST is a potent physiological inhibitor of glucose-induced insulin secretion. Recently, several SNPs were identified in the CST and PST domains of CHGA locus in different populations. Among the discovered SNPs, CST variant allele Ser-364 was associated with blood pressure alteration and PST variant allele Ser-297 was associated with significantly higher plasma glucose level. In this study, we examined whether these CST and PST variant alleles exist and influence cardiovascular and metabolic phenotypes in Japanese population. Our study comprised of 343 Japanese subjects aged 45-85 years (143 men and 200 women, mean age 66 ± 8 years). We determined the genotypes of CST and PST by PCR-direct sequencing method and carried out genotype-phenotype association analysis. In 343 participants, the minor allele frequency of CST variant Ser-364 was 6.10%. On the other hand, we did not detect the PST variant Ser-297 in this entire study population. The presence of Ser-364 allele was associated with increased in baPWV (an index of systemic arterial stiffness) that suggests an initiation and/or progression atherogenesis and hypertension. The Ser-364 allele was also associated with elevated systolic blood pressure and pulse pressure, consistent with increased baPWV. In conclusion, the CST Ser-364 allele may increase the risk for cardiovascular diseases in Japanese population.
Patients with Cushing’s syndrome (CS) frequently develop hyperthyroidism after surgery due to SITSH (syndrome of inappropriate secretion of TSH) and this SITSH contributed to the symptoms of steroid withdrawal syndrome (SWS). However, the duration of fluctuations in thyroid hormones after surgery for CS remains unknown. The aim of this prospective study was to investigate the clinical course of fluctuation in thyroid hormone level in CS patients after surgery. Thyroid hormone levels [free T3 (FT3), free T4 (FT4) and TSH] and serum cortisol levels were measured before and 1, 3, 6 and 12 months after surgery in 8 patients with active CS (3 pituitary CS and 5 adrenal CS). FT3 levels were above the normal range in 75% of patients up to 6 months after surgery, but returned to the normal range by 12 months. However, TSH levels were not suppressed below the normal range throughout the first 12 months after surgery. Serious symptoms of SWS appeared during the 6-month period after surgery, but disappeared with normalization of thyroid function at 12 months, which was not related to the recovery of function hypothalamus-pituitary-adrenal axis after CS surgery. Therefore, T3 toxicosis could result in deterioration of SWS after surgery for CS. These results indicate that physicians need to take T3 toxicosis into consideration in the pathological evaluation of SWS within 12 months after surgery for CS.
A nationwide epidemiologic survey of fibroblast growth factor 23 (FGF23)-related hypophosphatemic diseases was conducted in 2010 to clarify the prevalence and the clinical presentations of the disorders. A questionnaire inquiring the experience of patients with these diseases was sent to randomly selected hospitals throughout Japan. The estimated annual incidence of the diseases was 117 cases (95% CI 75 - 160), 55 males (95% CI 30 - 81) and 62 females (95% CI 40 - 84). Tumor-induced osteomalacia (TIO) and X-linked hypophosphatemic rickets (XLH) were the most prevalent causes of acquired and genetic FGF23-related hypophosphatemic diseases, respectively. The estimated incidence of XLH was about 1 in 20,000. We have also collected clinical data of the patients by a secondary survey. These patients showed FGF23 levels of above 30 pg/mL by intact assay in the presence of hypophosphatemia. While complete resection of responsible tumors improved biochemical abnormalities in patients with TIO, treatment with phosphate and/or active vitamin D3 did not normalize serum phosphate and tubular maximum transport of phosphate in patients with XLH. Our results suggest that there is no racial difference in the incidence of XLH. While FGF23 measurement is useful for the diagnosis of FGF23-related hypophosphatemic diseases, the better management is necessary especially for patients with genetic hypophosphatemic rickets caused by excessive actions of FGF23.
Glycemic variability (GV) has been proposed as contributor to diabetes-related macrovascular complications. This randomized control trial evaluated a new combination therapy with continuous subcutaneous insulin infusion (CSII) plus sitagliptin (CSII + sitagliptin) vs. CSII only in terms of metabolic control, GV and β-cell function in patients with newly diagnosed type 2 diabetes (T2DM). 217 patients were randomized to two weeks of CSII (n = 108) or CSII + sitagliptin (n = 109) therapy. As a measure of GV, the coefficient of variation (CV) was computed from capillary blood glucose during the first and second week, respectively. β-cell function before and after treatment was determined with the Insulin Secretion-Sensitivity Index-2 (ISSI-2). Good metabolic controls were established with both therapies. CSII + sitagliptin therapy resulted in greater improvements in CV and ISSI-2 than CSII alone (all P = 0.000). For each group, change in CV was inversely correlated with change in ISSI-2 (r = -0.529, P = 0.000 and r = -0.433, P = 0.000, respectively). The multivariate regression analysis demonstrated that improved ISSI-2 was the only independent contributor to reduced CV in both groups (standardized β = -0.388, P = 0.004 and standardized β = -0.472, P = 0.000, respectively). Correction of β-cell function in newly diagnosed T2DM patients via use of either CSII or CSII + sitagliptin therapy was feasible in controlling GV to prevent secondary complications of T2DM. Moreover, CSII + sitagliptin therapy was superior to CSII monotherapy in terms of GV.
The objective of this study was to investigate the impact of neuropeptide Y (NPY) on preadipocyte proliferation and differentiation. Preadipocytes were incubated with a range of concentrations of NPY (10-15M - 10-7M). After NPY-induced differentiation, the extent of preadipocyte adipogenesis was evaluated. The expressions levels of related adipocyte markers such as PPARγ, C/EBPα and DLK-1 were examined by real-time PCR (RT-PCR) or western blot analysis. Furthermore, the mitogen-activated protein kinase (MAPK) signaling pathway proteins were also analyzed by western blot. Our results showed that low doses of NPY stimulated preadipocyte viability and proliferation, while high NPY doses inhibited cell viability. At high concentrations of NPY significantly promoted lipid accumulation and increased the size of lipid droplets. DLK-1 mRNA expression was inhibited, but the expression levels of PPARγ and C/EBPα were increased during differentiation with the presence of high concentration of NPY. High-dose NPY also suppressed the phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2 protein. We conclude that NPY has a biphasic effect on preadipocyte proliferation. A high dose inhibits the proliferation of 3T3-L1 cell while promotes adipocyte differentiation, increasing lipid accumulation especially enlarged lipid droplets’ size. NPY may lead to a better understanding for drug development to prevent hyperplastic obesity and hypertrophic obesity.
The objectives of this study were to examine the prevalence of overactive bladder (OAB), including both with and without urinary incontinence, in patient with diabetes, and to explore factors related to the presence of OAB. This was a single-center, cross-sectional prospective survey. Patients with diabetes aged ≥18 years were consecutively enrolled in this study. Items related to OAB symptoms, neuropathic symptoms, clinical characteristics regarding diabetes management, and demographics were collected. The presence of OAB was assessed using the Overactive Bladder Symptoms Score (OABSS). Relationships between presence of OAB and potential related factors were explored by logistic regression analysis. The prevalence of OAB in the study cohort (n=652) was 24.2%, of which 71.5% was dry OAB (without urgency incontinence). Multivariate analysis showed that age (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.07-2.50) and symptomatic diabetic polyneuropathy (DPN) (OR 2.41, 95% CI 1.64-3.54) were significantly related to the presence of OAB. The OAB prevalence in our sample of patients with diabetes was approximately 2-fold higher than that of the Japanese general population, which was based on results obtained from questionnaires similar to the present study, although the OAB prevalence of 24.2% may slightly differ from the true value due to assessment of OAB using the questionnaire only. As OAB which is deteriorated QOL can be identified and treated, screening of OAB in patients with diabetes who have DPN or aged ≥65 years may contribute to achieving the therapeutic aim of maintaining QOL.