Regeneration of active glucocorticoids within liver and adipose tissue by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) may be of pathophysiological importance in obesity and Metabolic Syndrome and is a therapeutic target in type 2 diabetes. Polymorphisms in HSD11B1, the gene encoding 11β-HSD1, have been associated with metabolic phenotype in humans, including type 2 diabetes and hypertension. Here we have tested the functional consequences of 2 single nucleotide polymorphisms located in contexts that potentially affect tissue levels of 11β-HSD1. We report no effect of allelic variation at rs846910, a polymorphism within the 5′-flanking region of the gene on HSD11B1 promoter activity in vitro. However, compared to the common G allele, the A allele of rs13306421, a polymorphism located 2 nucleotides 5′ to the translation initiation site, gave higher 11β-HSD1 expression and activity in vitro and was translated at higher levels in in vitro translation reactions, possibly associated with a lower frequency of “leaky scanning”. These data suggest that this polymorphism may have direct functional consequences on levels of 11β-HSD1 enzyme activity in vivo. However, the rs13306421 A sequence variant originally reported in other ethnic groups may be of low prevalence as it was not detected in a population of 600 European caucasian women.
steroid metabolism; glucocorticoid; obesity; SNP; translation; regulation
The interactive nature of the 8th Annual Meeting of the Androgen Excess & PCOS Society Annual Meeting in Munich, Germany (AEPCOS 2010) and subsequent exchanges between speakers led to emerging concepts in PCOS regarding its genesis, metabolic dysfunction, and clinical treatment of inflammation, metabolic dysfunction, anovulation and hirsutism. Transition of care in congenital adrenal hyperplasia from pediatric to adult providers emerged as a potential model for care transition involving PCOS adolescents.
Developmental programming; clomiphene citrate; aromatase inhibitors; metformin; lifestyle intervention; advanced glycated end products; inflammation; statins; congenital adrenal hyperplasia; hirsutism
Polycystic ovary syndrome (PCOS) recently has been identified as a risk factor associated with type 2 diabetes. However, the evidence derives from cross-sectional observational studies, retrospective studies, or short-term prospective studies. This long-term prospective study of a large cohort of women with PCOS, followed from youth to middle age, aimed at estimating, for the first time, the incidence and potential predictors of type 2 diabetes in this population. A total of 255 women with PCOS were followed for at least 10 years (mean follow-up 16.9 years). Six women were patients with diabetes at baseline, and another 42 women developed type 2 diabetes during the follow-up. The incidence rate of type 2 diabetes in the study population was 1.05 per 100 person-years. The age-standardized prevalence of diabetes at the end of follow-up was 39.3%, which is significantly higher with respect to that of the general Italian female population of a similar age (5.8%). The likelihood of developing type 2 diabetes significantly increased as BMI, fasting glucose, and glucose area under the curve at baseline increased and significantly decreased as sex hormone–binding globulin (SHBG) levels at follow-up increased. This study demonstrates that the risk of type 2 diabetes is markedly elevated in middle-aged women with PCOS and suggests including BMI, glucose, and SHBG-circulating levels in the risk stratification.
To summarize promising areas of investigation into polycystic ovary syndrome (PCOS) and to stimulate further research in this area.
Potential areas of further research activity include the analysis of predisposing conditions that increase the risk of PCOS, particularly genetic background and environmental factors, such as endocrine disruptors and lifestyle. The concept that androgen excess may contribute to insulin resistance needs to be re-examined from a developmental perspective, since animal studies have supported the hypothesis that early exposure to modest androgen excess is associated with insulin resistance. Defining alterations of steroidogenesis in PCOS should quantify ovarian, adrenal and extraglandular contribution, as well as clearly define blood reference levels by some universal standard. Intraovarian regulation of follicle development and mechanisms of follicle arrest should be further elucidated. Finally, PCOS status is expected to have long-term consequences in women, specifically the development of type 2 diabetes, cardiovascular diseases and hormone dependent cancers. Identifying susceptible individuals through genomic and proteomic approaches would help to individualize therapy and prevention. A potential limitation of our review is that we focused selectively on areas we viewed as the most controversial.
steroids; androgens; folliculogenesis; inflammation; anovulation
Several lines of evidence suggest that novel pharmacological approaches aimed at converting white adipose tissue (WAT) into brown adipose tissue (BAT) may represent an effective therapeutic strategy for obesity and related disorders. (18)F-fluorodeoxyglucose (18F-FDG) is the only positron emission tomography (PET) tracer commonly used to study BAT function, and so far no functional tools have been described to investigate in vivo white-to-brown fat conversion. In this report, we show that the PET tracer 11C-meta-hydroxyephedrine (11C-MHED, a norepinephrine analogue) is a useful tool to investigate the sympathetic nervous system (SNS) activity in BAT of lean and dietary obese mice. Moreover, we demonstrate that 11C-MHED is a specific marker of the SNS-mediated thermogenesis in typical BAT depots, and that this tracer can detect in vivo WAT to BAT conversion.
Brown adipose tissue; Sympathetic activity; PET/CT imaging
Type 2 diabetes mellitus is the result of interaction between genetic and environmental factors, leading to heterogeneous and progressive pancreatic β-cell dysfunction. Overweight and obesity are major contributors to the development of insulin resistance and impaired glucose tolerance. The inability of β cells to secrete enough insulin produces type 2 diabetes. Abnormalities in other hormones such as reduced secretion of the incretin glucagon-like peptide 1 (GLP-1), hyperglucagonemia, and raised concentrations of other counterregulatory hormones also contribute to insulin resistance, reduced insulin secretion, and hyperglycaemia in type 2 diabetes. Clinical-overt and experimental cortisol excess is associated with profound metabolic disturbances of intermediate metabolism resulting in abdominal obesity, insulin resistance, and low HDL-cholesterol levels, which can lead to diabetes. It was therefore suggested that subtle abnormalities in cortisol secretion and action are one of the missing links between insulin resistance and other features of the metabolic syndrome. The aim of this paper is to address the role of glucocorticoids on glucose homeostasis and to explain the relationship between hypercortisolism and type 2 diabetes.
Prelamin A processing impairment is a common feature of a restricted group of rare genetic alterations/disorders associated with a wide range of clinical phenotypes. Changes in histone posttranslational modifications, alterations in non-histone chromatin proteins and chromatin disorganization have been specifically linked to impairment of specific, distinct prelamin A processing steps, but the molecular mechanism involved in these processes is not yet understood . In this study, we show that the accumulation of wild-type prelamin A detected in restrictive dermopathy (RD), as well as the accumulation of mutated forms of prelamin A identified in familial partial lipodystrophy (FPLD) and mandibuloacral dysplasia (MADA), affect the nuclear localization of barrier-to-autointegration factor (BAF), a protein able to link lamin A precursor to chromatin remodeling functions. Our findings, in accordance with previously described results, support the hypothesis of a prelamin A involvement in BAF nuclear recruitment and suggest BAF-prelamin A complex as a protein platform usually activated in prelamin A-accumulating diseases. Finally, we demonstrate the involvement of the inner nuclear membrane protein emerin in the proper localization of BAF-prelamin A complex.
BAF; BANF1; prelamin A; lamin A/C; laminopathies; emerin; EDMD1
The need for a collaborative approach to complex inherited diseases collectively referred to as laminopathies, encouraged Italian researchers, geneticists, physicians and patients to join in the Italian Network for Laminopathies, in 2009. Here, we highlight the advantages and added value of such a multidisciplinary effort to understand pathogenesis, clinical aspects and try to find a cure for Emery-Dreifuss muscular dystrophy, Mandibuloacral dysplasia, Hutchinson-Gilford Progeria and forms of lamin-linked cardiomyopathy, neuropathy and lipodystrophy.
Laminopathies; Emery-Dreifuss Muscular Dystrophy; Dilated Cardiomyopathy with Conduction Defects; Mandibuloacral Dysplasia; Familial Partial Lipodystrophy Type 2; Hutchinson-Gilford Progeria Syndrome; Rare Diseases; Networking activity; interdisciplinary approach to diseases
The prevalence of obesity and related diseases has increased enormously in the last few decades, becoming a very important medical and social issue. Because of the increasing number of people who need weight loss therapies and the high costs associated with these, the search for reliable predictors of success for weight loss and weight maintenance treatments has become a priority.
A literature review was undertaken to identify possible predictors of outcome of weight loss and weight maintenance in patients treated with antiobesity drugs.
For the majority of variables, published data are not sufficient to define their role on final outcomes. Among all considered factors, only early response to treatment appeared to be a reliable positive predictor, and diabetes a negative predictor of weight loss and maintenance.
To date, no definitive results have been obtained. Due to the great benefits of reliable predictors of outcome associated to currently available antiobesity drugs and those under development, identifying these predictors has to be supported and encouraged.
obesity; weight loss predictors; pharmacological treatment
OBJECTIVE—Cannabinoid type 1 (CB1) receptor blockade decreases body weight and adiposity in obese subjects; however, the underlying mechanism is not yet fully understood. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) induces mitochondrial biogenesis and function in adipocytes. This study was undertaken to test whether CB1 receptor blockade increases the espression of eNOS and mitochondrial biogenesis in white adipocytes.
RESEARCH DESIGN AND METHODS—We examined the effects on eNOS and mitochondrial biogenesis of selective pharmacological blockade of CB1 receptors by SR141716 (rimonabant) in mouse primary white adipocytes. We also examined eNOS expression and mitochondrial biogenesis in white adipose tissue (WAT) and isolated mature white adipocytes of CB1 receptor–deficient (CB1−/−) and chronically SR141716-treated mice on either a standard or high-fat diet.
RESULTS—SR141716 treatment increased eNOS expression in cultured white adipocytes. Moreover, SR141716 increased mitochondrial DNA amount, mRNA levels of genes involved in mitochondrial biogenesis, and mitochondrial mass and function through eNOS induction, as demonstrated by reversal of SR141716 effects by small interfering RNA–mediated decrease in eNOS. While high-fat diet–fed wild-type mice showed reduced eNOS expression and mitochondrial biogenesis in WAT and isolated mature white adipocytes, genetic CB1 receptor deletion or chronic treatment with SR141716 restored these parameters to the levels observed in wild-type mice on the standard diet, an effect linked to the prevention of adiposity and body weight increase.
CONCLUSIONS—CB1 receptor blockade increases mitochondrial biogenesis in white adipocytes by inducing the expression of eNOS. This is linked to the prevention of high-fat diet–induced fat accumulation, without concomitant changes in food intake.
The cannabinoid receptor type 1 (CB1) and its endogenous ligands, the endocannabinoids, are involved in the regulation of food intake. Here we show that the lack of CB1 in mice with a disrupted CB1 gene causes hypophagia and leanness. As compared with WT (CB1+/+) littermates, mice lacking CB1 (CB1–/–) exhibited reduced spontaneous caloric intake and, as a consequence of reduced total fat mass, decreased body weight. In young CB1–/– mice, the lean phenotype is predominantly caused by decreased caloric intake, whereas in adult CB1–/– mice, metabolic factors appear to contribute to the lean phenotype. No significant differences between genotypes were detected regarding locomotor activity, body temperature, or energy expenditure. Hypothalamic CB1 mRNA was found to be coexpressed with neuropeptides known to modulate food intake, such as corticotropin-releasing hormone (CRH), cocaine-amphetamine–regulated transcript (CART), melanin-concentrating hormone (MCH), and prepro-orexin, indicating a possible role for endocannabinoid receptors within central networks governing appetite. CB1–/– mice showed significantly increased CRH mRNA levels in the paraventricular nucleus and reduced CART mRNA levels in the dorsomedial and lateral hypothalamic areas. CB1 was also detected in epidydimal mouse adipocytes, and CB1-specific activation enhanced lipogenesis in primary adipocyte cultures. Our results indicate that the cannabinoid system is an essential endogenous regulator of energy homeostasis via central orexigenic as well as peripheral lipogenic mechanisms and might therefore represent a promising target to treat diseases characterized by impaired energy balance.
Obesity, particularly the abdominal phenotype, has been ascribed to an individual maladaptation to chronic environmental stress exposure mediated by a dysregulation of related neuroendocrine axes. Alterations in the control and action of the hypothalamic–pituitary–adrenal axis play a major role in this context, with the participation of the sympathetic nervous system. The ability to adapt to chronic stress may differ according to sex, with specific pathophysiological events leading to the development of stress-related chronic diseases. This seems to be influenced by the regulatory effects of sex hormones, particularly androgens. Stress may also disrupt the control of feeding, with some differences according to sex. Finally, the amount of experimental data in both animals and humans may help to shed more light on specific phenotypes of obesity, strictly related to the chronic exposure to stress. This challenge may potentially imply a different pathophysiological perspective and, possibly, a specific treatment.
cortisol; androgens; stress; obesity