Sex Hormone-binding Globulin Protein Research Articles

Susceptibility of Human Spermatozoa to Titanium Dioxide Nanoparticles: Evaluation of DNA Damage and Biomarkers.

Nowadays, developing countries have seen a reduction in male reproductive parameters, and it has been linked to the exposure of endocrine disrupting chemicals (EDCs), which are able to mimic or disrupt steroid hormone actions. Also, nanoparticles have shown effects on the male reproductive system, in particular the use of TiO2-NPs in drugs, cosmetics, and food as pigment additives, and, thanks to their small size (1-100 nm), provide themselves the opportunity to be internalized by the body and pass the blood-testis barrier (BTB). Therefore, TiO2-NPs can act on spermatogenesis and spermatozoa. In this study, we carried out an in vitro assay on human spermatozoa to evaluate the effects of TiO2-NPs at the concentrations of 500, 250, 100, and 50 ppm. Exposure did not statistically alter sperm parameters (e.g., motility and viability) but induced damage to sperm DNA and the expression of biomarkers by spermatozoa. This immunofluorescence investigation showed a positivity for biomarkers of stress (HSP70 and MTs) on the connecting piece of spermatozoa and also for sex hormone binding globulin (SHBG) biomarkers. The SHBG protein acts as a carrier of androgens and estrogens, regulating their bioavailability; therefore, its expression in the in vitro assay did not rule out the ability of TiO2-NPs to act as endocrine disruptors.

Hormonal biomarkers and preterm birth: insights from a study of pregnant women in Lahore, Pakistan.

Objective. Reduced calciferol (vitamin D) levels in pregnant women have been associated with an increased risk to infant health. Progesterone sustains pregnancy and reduces the risk of premature birth through its metabolites affecting myometrial contractility. Sex hormone-binding globulin protein (SHBG) is a biomarker of premature birth. The present study aimed to find out if early pregnancy levels of vitamin D, SHBG, and progesterone metabolites may predict preterm birth risk. Methods. Five hundred pregnant women aged 18-43 years during their 2nd and 3rd trimesters from multiple civilian regional medical centers in Lahore participated in the study. Blood samples taken from participants were used to determine vitamin D, SHBG, 11-deoxycorticosterone (DOC), and 16α-hydroxyprogesterone (16α-OHP) levels using specific ELISA kits. Statistical analysis was performed by one-way ANOVA using the latest GraphPad Prism software. Results. A significant decrease in vitamin D, DOC, and SHBG levels (p<0.001, p<0.001, and p<0.05, respectively) in the preterm birth cohorts in the 2nd and 3rd trimester was found compared to the corresponding control groups. Furthermore, 16α-OHP levels in the preterm birth cohorts in the 2nd and 3rd trimesters were significantly increased (p<0.001 and p=0.0062, respectively) compared to their control cohorts. Conclusion. The results of our study confirm that calciferol deficiency in pregnant women is associated with an increased risk of premature birth and indicate that SHBG and progesterone metabolites may be useful biomarkers for the early identification and prediction of preterm birth.

Sex hormone-binding globulin promotes the osteogenic differentiation potential of equine adipose-derived stromal cells by activating the BMP signaling pathway.

Musculoskeletal injuries and chronic degenerative diseases pose significant challenges in equine health, impacting performance and overall well-being. Sex Hormone-Binding Globulin (SHBG) is a glycoprotein determining the bioavailability of sex hormones in the bloodstream, and exerting critical metabolic functions, thus impacting the homeostasis of many tissues including the bone. In this study, we investigated the potential role of SHBG in promoting osteogenesis and its underlying mechanisms in a model of equine adipose-derived stromal cells (ASCs). An SHBG-knocked down model has been established using predesigned siRNA, and cells subjected to osteogenic induction medium in the presence of exogenous SHBG protein. Changes in differentiation events where then screened using various analytical methods. We demonstrated that SHBG treatment enhances the expression of key osteoconductive regulators in equine ASCs CD34+ cells, suggesting its therapeutic potential for bone regeneration. Specifically, SHBG increased the cellular expression of BMP2/4, osteocalcin (OCL), alkaline phosphatase (ALP), and osteopontin (OPN), crucial factors in early osteogenesis. Furthermore, SHBG treatment maintained adequate apoptosis and enhanced autophagy during osteogenic differentiation, contributing to bone formation and remodeling. SHBG further targeted mitochondrial dynamics, and promoted the reorganization of the mitochondrial network, as well as the expression of dynamics mediators including PINK, PARKIN and MFN1, suggesting its role in adapting cells to the osteogenic milieu, with implications for osteoblast maturation and differentiation. Overall, our findings provide novel insights into SHBG's role in bone formation and suggest its potential therapeutic utility for bone regeneration in equine medicine.

Sex hormone-binding globulin improves lipid metabolism and reduces inflammation in subcutaneous adipose tissue of metabolic syndrome-affected horses.

Equine metabolic syndrome (EMS) is a steadily growing endocrine disorder representing a real challenge in veterinary practice. As a multifactorial condition, EMS is characterized by three main metabolic abnormalities including insulin resistance, increased adiposity or obesity and hoof laminitis. Adipose tissue dysfunction is recognized as a core pathophysiological determinant of EMS, as it strongly participates to lipotoxicity and systemic metaflammation, both of which have been closely linked to the development of generalized insulin resistance. Besides, sex hormone binding globulin (SHBG) is an important sex steroids transporters that has been recently proposed as an important metabolic mediator. Therefore, the aim of this study was to verify whether SHBG treatment may ameliorate subcutaneous adipose tissue metabolic failure under EMS condition in terms of lipidome homeostasis, lipid metabolism programs, insulin signalling and local inflammation. Subcutaneous adipose tissue (SAT) biopsies were collected post-mortem from healthy (n = 3) and EMS (n = 3) slaughtered horses. SHBG protein has been applied to SAT samples from EMS horses for 24h at a final concentration of 50nM, while control groups (healthy and untreated EMS) were cultured in the presence of SHBG-vehicle only. Tissues from all groups were afterwards secured for downstream analysis of gene expression using RT-qPCR, protein levels by Western blot and ELISA assay and lipidomics through GC-MS technique. Obtained results showcased that SHBG intervention efficiently normalized the altered fatty acids (FAs) profiles by lowering the accumulation of saturated and trans FAs, as well as the pro-inflammatory arachidonic and linoleic acids. Moreover, SHBG showed promising value for the regulation of adipocyte lipolysis and engorgement by lowering the levels of perilipin-1. SHBG exerted moderated effect toward SCD1 and FASN enzymes expression, but increased the LPL abundance. Interestingly, SHBG exhibited a negative regulatory effect on pro-adipogenic stimulators and induced higher expression of KLF3, IRF3 and β-catenin, known as strong adipogenesis repressors. Finally, SHBG protein showed remarkable ability in restoring the insulin signal transduction, IR/IRS/Pi3K/AKT phosphorylation events and GLUT4 transporter abundance, and further attenuate pro-inflammatory response by lowering IL-6 tissue levels and targeting the PDIA3/ERK axis. Overall, the obtained data clearly demonstrate the benefice of SHBG treatment in the regulation of adipose tissue metabolism in the course of EMS and provide new insights for the development of molecular therapies with potential translational application to human metabolic disorders.

Genetic regulation of testosterone level in overweight males from the Kazakh population and its association with hypogonadism.

Male hypogonadism and erectile dysfunction in different populations are associated with excess body weight. A key aspect in most studies is the metabolism of sexual hormones, primarily testosterone. At the same time, the binding protein sex hormone binding globulin (SHBG) can play a large role, as it determines the ratio of total and bioavailable testosterone in blood, i.e. both the hormone content and level of its production. Recent research has identified common mutations that affect SHBG levels, such as the rs727428 polymorphic locus, which is associated with alterations in histone protein function, affecting the regulation of ribonucleic acid (RNA) protein SHBG synthesis. Similar relationships have been observed for prevalent mutations, including rs5934505 and rs10822184, in diverse populations. This study involved 300 individuals of Kazakh nationality from the Eastern Kazakhstan region, examining three polymorphic variants of the SHBG gene (rs727428, rs5934505, and rs10822184). The participants were categorized into three groups: individuals with hypogonadism and obesity (group 1, n=85), those with excess body weight but no hypogonadism (group 2, n=70), and individuals with neither excess body weight nor hypogonadism (group 3, n=145). The frequency of mutant gene alleles impacting GPS (SHBG) synthesis in the Kazakh population was notably high, comparable to European and South-East Asian populations. However, the association between excess body weight and these mutations exhibited varying patterns. Hypogonadism was linked to decreased GPS levels, strongly correlating with total testosterone but not bioavailable testosterone. The retention of sexual functions in overweight men was not always directly related to BMI levels and GPS concentrations.

Sex Hormone-Binding Globulin (SHBG) Maintains Proper Equine Adipose-Derived Stromal Cells (ASCs)’ Metabolic Functions and Negatively Regulates their Basal Adipogenic Potential

BackgroundSex hormone binding globulin (SHBG) deteriorated expression has been recently strongly correlated to increased level of circulating pro-inflammatory cytokines and insulin resistance, which are typical manifestations of equine metabolic syndrome (EMS). Despite previous reports demonstrated the potential therapeutic application of SHBG for liver-related dysfunctions, whether SHBG might modulate equine adipose-derived stem/stromal cells (EqASCs) metabolic machinery remains unknown. Therefore, we evaluated for the first time the impact of SHBG protein on metabolic changes in ASCs isolated from healthy horses.MethodsBeforehand, SHBG protein expression has been experimentally lowered using a predesigned siRNA in EqASCs to verify its metabolic implications and potential therapeutic value. Then, apoptosis profile, oxidative stress, mitochondrial network dynamics and basal adipogenic potential have been evaluated using various molecular and analytical techniques.ResultsThe SHBG knockdown altered the proliferative and metabolic activity of EqASCs, while dampening basal apoptosis via Bax transcript suppression. Furthermore, the cells treated with siRNA were characterized by senescent phenotype, accumulation of reactive oxygen species (ROS), nitric oxide, as well as decreased mitochondrial potential that was shown by mitochondrial membrane depolarization and lower expression of key mitophagy factors: PINK, PARKIN and MFN. The addition of SHBG protein reversed the impaired and senescent phenotype of EMS-like cells that was proven by enhanced proliferative activity, reduced apoptosis resistance, lower ROS accumulation and greater mitochondrial dynamics, which is proposed to be related to a normalization of Bax expression. Crucially, SHBG silencing enhanced the expression of key pro-adipogenic effectors, while decreased the abundance of anti-adipogenic factors namely HIF1-α and FABP4. The addition of exogenous SHBG further depleted the expression of PPARγ and C/EBPα and restored the levels of FABP4 and HIF1-α evoking a strong inhibitory potential toward ASCs adipogenesis.ConclusionHerein, we provide for the first time the evidence that SHBG protein in importantly involved in various key metabolic pathways governing EqASCs functions, and more importantly we showed that SHBG negatively affect the basal adipogenic potential of tested ASCs through a FABP4-dependant pathway, and provide thus new insights for the development of potential anti-obesity therapeutic approach in both animals and humans.Graphical

Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology.

According to the free hormone hypothesis, biological activity of a certain hormone is best reflected by free rather than total hormone concentrations. A crucial element in this theory is the presence of binding proteins, which function as gatekeepers for steroid action. For testosterone, tissue exposure is governed by a delicate equilibrium between free and total testosterone which is determined through interaction with the binding proteins sex hormone-binding globulin and albumin. Ageing, genetics and various pathological conditions influence this equilibrium, hereby possibly modulating hormonal exposure to the target tissues. Despite ongoing controversy on the subject, strong evidence from recent in vitro, in vivo and human experiments emphasizes the relevance of free testosterone. Currently, however, clinical possibilities for free hormone diagnostics are limited. Direct immunoassays are inaccurate, while gold standard liquid chromatography with tandem mass spectrometry (LC-MS/MS) coupled equilibrium dialysis is not available for clinical routine. Calculation models for free testosterone, despite intrinsic limitations, provide a suitable alternative, of which the Vermeulen calculator is currently the preferred method. Calculated free testosterone is indeed associated with bone health, frailty and other clinical endpoints. Moreover, the added value of free testosterone in the clinical diagnosis of male hypogonadism is clearly evident. In suspected hypogonadal men in whom borderline low total testosterone and/or altered sex hormone-binding globulin levels are detected, the determination of free testosterone avoids under- and overdiagnosis, facilitating adequate prescription of hormonal replacement therapy. As such, free testosterone should be integrated as a standard biochemical parameter, on top of total testosterone, in the diagnostic workflow of male hypogonadism.

Could Hormone Levels Impact the Severity of Clitoral Phimosis?

ABSTRACT Introduction Clitoral adhesions (CA) occur when the prepuce adheres to the glans clitoris. CA can be classified as mild, moderate, or severe, based on if more than 75%, 25% to 75%, or less than 25% of the glans clitoris is exposed. Symptoms of CA include pain, difficulty with arousal, and muted or absent orgasm. There is a paucity of information on how hormone levels may contribute to the formation of CA. We hypothesize that patients with lower levels of free and total testosterone, and higher levels of the blood transport protein sex hormone binding globulin (SHBG) could have more severe adhesions. Higher free and total testosterone can yield more oily skin, which may break up or prevent adhesions. Additionally, with higher SHBG, there is less free testosterone available to be used by tissues in the body. Objective To determine if patients with lower free and total testosterone, and higher SHBG have more severe adhesions. Methods Charts of females with CA who underwent the non-surgical lysis procedure at one sexual medicine practice were considered for this study. 24 charts contained information on the severity of phimosis before lysis, total and free testosterone levels, as well as SHBG levels around the time of lysis. The study group consisted of patients with mild (n=9), moderate (n=8), or severe (n=7) CA. Results The average calculated free testosterone among patients with mild, moderate, and severe CA was 0.23ng/dL, 0.35ng/dL, and 0.14ng/dL. The average total testosterone among patients with mild, moderate, and severe CA was 24.79ng/dL, 27.81ng/dL, and 20.26ng/dL. The average SHBG among patients with mild, moderate, and severe CA was 98.69nmol/L, 95.76nmol/L, and 109.40nmol/L. Conclusions We predicted that patients with more severe adhesions would have lower levels of free and total testosterone, as well as higher levels of SHBG, yet this trend did not appear overall in this data among patients with mild, moderate, or severe adhesions. Additional studies with larger sample sizes are needed to explore the potential impact of free and total testosterone, as well as SHBG levels on the development and severity of CA. Studies could also compare levels of these hormones in patients with and without adhesions, or consider patients with recurrence of adhesions. Insight into a hormonal etiology could be important to patients with altered levels of these hormones - for example, patients with medical conditions such as PCOS, patients taking medications such as oral contraceptive pills, and menopausal women on oral estrogen (as increased estrogen raises levels of SHBG) could be at an increased risk for developing CA. Further studies could also consider if the clitoides of transgender males on gender-affirming hormone therapy with testosterone have lower incidences of CA. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Sprout (Raleigh, NC), Absorption Pharmaceuticals

Association of Macronutrients Composition, Physical Activity and Serum Androgen Concentration in Young Women with Polycystic Ovary Syndrome.

The roles of dietary macronutrients and physical activity (PA) in patients with PCOS have not been sufficiently reported, especially in adolescent girls. To address this knowledge gap, we evaluated the associations between serum concentrations of total testosterone (tT), free testosterone (fT), androstenedione (A), dehydroepiandrosterone-sulfate (DHEA-S), sex hormone-binding globulin (SHBG) and dietary macronutrients intake as well as different types and levels of PA. The study population consisted of 96 girls of Caucasian ancestry, aged 14–18 years: 61 participants with polycystic ovary syndrome (PCOS) and 35 healthy controls. Serum tT, fT, A, DHEA-S, and SHBG were determined in fasting blood. Macronutrient intake and PA levels were assessed by using the three-day food record method and the Beliefs and Eating Habits Questionnaire (KomPAN), respectively. We found several positive correlations between dietary macronutrients such as total fat, saturated fatty acids (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), and hormonal parameters across the entire cohort and in healthy girls. A positive correlation between SHBG and total protein consumption as well as an inverse correlation between SHBG and carbohydrate intake could be determined. No correlation between androgens and macronutrients was found in the PCOS group. In contrast, we observed an inverse correlation between androgen concentrations (except of DHEA-S) and “work/school” and/or “leisure time” PA only in PCOS patients. Moreover, the hormone levels differed according to PA intensity. In conclusion, the impact of diet and PA was strikingly different in adolescents with and without PCOS. These findings indicate that disturbed hormonal homeostasis in PCOS, at least in the youngest patients, likely “overtrump” dietary influences, and otherwise, PA offers a therapeutic potential that requires further evaluation of the long-term effects in randomized studies. (ClinicalTrial.gov Identifier: NCT04738409.)

Gynecomastia as a presenting symptom of Graves' disease in a 49-year-old man.

SummaryGynecomastia is a symptom with a potential high disease burden. It has a variety of underlying causes, such as malignant, drug-related or hormonal. The presence of gynecomastia can be explained in thyrotoxicosis due to a concomitant disbalance of sex hormones. Interestingly, it rarely is the presenting symptom of Graves’ disease. A 49-year-old man presented to our outpatient clinic with right-sided gynecomastia. After thorough history taking, more symptoms of thyrotoxicosis were present. Treatment was started with thiamazole and later levothyroxine. Three months after this treatment the gynecomastia and other symptoms resolved completely. A disbalance of sex hormones due to an increased expression of the protein sex hormone-binding globulin (SHBG) caused by thyrotoxicosis could result in gynecomastia. In vitro and in vivo research in mice suggest that the pathophysiology of thyrotoxicosis-associated gynecomastia is due to upregulation of hepatocyte nuclear factor-4α (HNF4A) in liver cells. Subsequent increase of SHBG results in a decrease of free testosterone levels.Learning points Gynecomastia is a common finding (up to almost 40%) on physical examination in patients with hyperthyroidism. In gynecomastia, thyroid function tests should be examined on initial presentation because of the relative simple treatment. The pathophysiology of thyrotoxicosis-associated gynecomastia is well understood by a sex-hormonal disbalance due to an increased expression of SHBG. Due to the well explainable pathophysiology, reduction of symptoms can be expected after treatment. The underlying mechanism of an increased expression of SHBG is not well understood. However, in vitro and in vivo research in mice suggests that thyrotoxicosis causes an increased expression of HNF4A in liver cells. Thus, upregulating the expression of SHBG. Interestingly, HNF4A is suspected to play an important role in MODY. Future research will clarify the importance of this gene and might open up new insights for therapy.

Serum Decorin and Biglycan as Potential Biomarkers to Predict PPROM in Early Gestation

Preterm birth is a leading cause of neonatal mortality in the US and globally, with preterm premature rupture of fetal membranes (PPROM) accounting for one third of preterm births. Currently no predictive diagnostics are available to precisely assess risk and potentially reduce the incidence of PPROM. Bigycan and decorin, the main proteoglycans present in human fetal membranes, are involved in the physiological maturation of fetal membranes as well as in the pathophysiology of preterm birth. The serum protein sex hormone-binding globulin (SHBG) has recently been identified as a predictor of spontaneous preterm birth. We hypothesize that the balance between serum decorin and biglycan on one hand and SHBG on the other hand may provide insight into the status of the fetal membranes in early pregnancy, thereby predicting PPROM prior to symptoms. Using chart review, 18 patients with confirmed cases of PPROM were identified from 2013-2016. Second trimester residual serum was retreived from freezer storage for these cases along with 5 matched controls for each case. The biomarkers biglycan, decorin and SHBG were analyzed first separately, then in combination to determine their ability to predict PPROM. The predictive score for the combined model displays an AUC = 0.774. The ROC curve of the predicted score has an optimal threshold of 0.238 and a sensitivity and specificity of 0.72 and 0.84 respectively. This prenatal serum panel is a promising serum screening-based biochemical model to predict PPROM in asymptomatic women.

Serum Decorin and Biglycan as Potential Biomarkers to Predict PPROM in Early Gestation.

Preterm birth is a leading cause of neonatal mortality in the US and globally, with preterm premature rupture of fetal membranes (PPROM) accounting for one third of preterm births. Currently no predictive diagnostics are available to precisely assess risk and potentially reduce the incidence of PPROM. Bigycan and decorin, the main proteoglycans present in human fetal membranes, are involved in the physiological maturation of fetal membranes as well as in the pathophysiology of preterm birth. The serum protein sex hormone-binding globulin (SHBG) has recently been identified as a predictor of spontaneous preterm birth. We hypothesize that the balance between serum decorin and biglycan on one hand and SHBG on the other hand may provide insight into the status of the fetal membranes in early pregnancy, thereby predicting PPROM prior to symptoms. Using chart review, 18 patients with confirmed cases of PPROM were identified from 2013-2016. Second trimester residual serum was retreived from freezer storage for these cases along with 5 matched controls for each case. The biomarkers biglycan, decorin and SHBG were analyzed first separately, then in combination to determine their ability to predict PPROM. The predictive score for the combined model displays an AUC = 0.774. The ROC curve of the predicted score has an optimal threshold of 0.238 and a sensitivity and specificity of 0.72 and 0.84 respectively. This prenatal serum panel is a promising serum screening-based biochemical model to predict PPROM in asymptomatic women.

Testosterone, sex hormone-binding globulin and risk of cardiovascular events: A report from the Outcome Reduction with an Initial Glargine Intervention trial.

Testosterone and its binding protein sex hormone-binding globulin have been associated with cardiovascular disease and dysglycaemia. However, information on the prognostic implication in patients at high cardiovascular risk with dysglycaemia is inconsistent. The study objective was to determine whether testosterone and/or sex hormone-binding globulin predict cardiovascular events or death in dysglycaemic patients. Dysglycaemic males at high cardiovascular risk ( n = 5553) who participated in the Outcome Reduction with an Initial Glargine Intervention (ORIGIN) trial and provided baseline blood samples were studied. Testosterone and sex hormone-binding globulin were measured at baseline and used to estimate free testosterone. Low levels of total and free testosterone were defined as ≤300 ng/dl and ≤7 ng/dl, respectively. Patients were followed for six years for cardiovascular events (defined as the composite of cardiovascular death, non-fatal myocardial infarction or stroke) and all-cause mortality. The mean total and free testosterone levels were 416.6 ng/dl and 8.4 ng/dl, and low levels were present in 13% and 37% of the patients. The median sex hormone-binding globulin level was 35 nmol/l. In Cox regression models adjusted for age, previous diseases and pharmacological treatment, neither total nor free testosterone predicted cardiovascular events. However, a one-standard-deviation increase in sex hormone-binding globulin predicted both cardiovascular events (hazard ratio 1.07; 95% confidence interval 1.00-1.14; p = 0.03) and all-cause mortality (hazard ratio 1.13; 95% confidence interval 1.06-1.21; p < 0.01). Sex hormone-binding globulin, but not total testosterone, predicts cardiovascular disease and all-cause mortality in dysglycaemic males at high cardiovascular risk.

Effect of placental sex hormone-binding globulin single nucleotide polymorphism rs6259 on protein and function in gestational diabetes mellitus.

Sex hormone-binding globulin (SHBG) has a key role in the occurrence and development of the gestational diab-etes mellitus(GDM). Single nucleotide polymorphism(SNP) rs6259 is a functional site in SHBGgene, which is suspected to regulate the SHBG level. The present study explored the placental SHBGSNPrs6259 distribution in Chinese pregnant women and the influence on placental SHBG concentrations, to assess the relationship of SHBGrs6259 in the occurrence and development of GDM. We screened the SHBG rs6259 allele in 210healthy and 180GDM gravidas by PCR-RFLP and restriction enzyme and measured placental SHBG concentrations in each genotypic group with western blot analysis. The mechanisms of SHBGrs6259 function were analyzed by cell culture, recombinant lentivirus transfection, real-time PCR, and western blot analysis. We found the differences of SHBGAsn327 allele frequency and the genotype distribution in GDM and control groups were statistically significant (P<0.05). Western blot analysis results showed that the Asn327 allele group was associated with a higher placental SHBG level than the Asp327 allele homozygote group (P<0.05). In HTR8-SVneo cell transfection, the positive transfection groups (SHBG-rs6259Asn) led to an obviously higher tendency of SHBG mRNA and protein expression than the negative control groups (SHBG-rs6259Asp), the normal cell group, and the blank control group (blank lentivirus LV-5)(P<0.05). Our data, therefore, reflected that SHBGSNPrs6259 causes changes in placental SHBG concentration and may play a functional role in the molecular mechanisms of GDM etiology.

SHBG expression is correlated with PI3K/AKT pathway activity in a cellular model of human insulin resistance

Decreased sex hormone-binding globulin (SHBG) expression is an independent risk factor for gestational diabetes mellitus(GDM).However, the mechanisms that link low SHBG expression and insulin resistance in GDM is unclear. In this study, we investigated the placenta SHBG in the PI3K/AKT pathway to reveal the mechanism that links decreased SHBG to insulin resistance. A insulin resistance cells model was established by the method of insulin stimulation. Two groups were set up, HTR8/Svneo cells and insulin-resistance cells of HTR8/SVneo. The expression of SHBG and PI3K/AKT associated factors were detected using real-time PCR and western blotting and their correlations were analyzed. The results showed that SHBG protein and mRNA levels in insulin resistance cells were both significantly lower. Along with decreased SHBG expression, the mRNA and protein levels of IRS-1, IRS-2, PI3Kp85α and GLUT-3, GLUT-4 decreased significantly. However, the expression of GLUT-1 increased significantly. Pearson correlation analysis showed that SHBG mRNA expression was positively correlated with IRS-1, IRS-2 and PI3Kp85α mRNA levels. According to the results, low SHBG expression not only participates in the development of local insulin resistance, but may also play an important role in PI3K/AKT pathway-mediated systemic insulin resistance and gestational diabetes.

Modulation of SHBG binding to testosterone and estradiol by sex and morbid obesity.

Sex hormone-binding globulin (SHBG) binds and transports testosterone and estradiol in plasma. The possibility that SHBG is a mixture of transporting proteins has been postulated. We analyzed in parallel the effects of obesity status on the levels and binding capacity of circulating SHBG and their relationship with testosterone and estradiol. Anthropometric measures and plasma were obtained from apparently healthy young (i.e. 35 ± 7 years) premenopausal women (n = 32) and men (n = 30), with normal weight and obesity (BMI >30 kg/m2). SHBG protein (Western blot), as well as the plasma levels of testosterone, estradiol, cortisol and insulin (ELISA) were measured. Specific binding of estradiol and testosterone to plasma SHBG was analyzed using tritium-labeled hormones. Significant differences in SHBG were observed within the obesity status and gender, with discordant patterns of change in testosterone and estradiol. In men, testosterone occupied most of the binding sites. Estrogen binding was much lower in all subjects. Lower SHBG of morbidly obese (BMI >40 kg/m2) subjects affected testosterone but not estradiol. The ratio of binding sites to SHBG protein levels was constant for testosterone, but not for estradiol. The influence of gender was maximal in morbid obesity, with men showing the highest binding/SHBG ratios. The results reported here are compatible with SHBG being a mixture of at least two functionally different hormone-binding globulins, being affected by obesity and gender and showing different structure, affinities for testosterone and estradiol and also different immunoreactivity.

Expression and correlation of sex hormone-binding globulin and insulin signal transduction and glucose transporter proteins in gestational diabetes mellitus placental tissue

ObjectiveThe aim of the present study was to investigate the probable pathogenesis of gestational diabetes mellitus (GDM) by analyzing the correlation between sex hormone-binding globulin (SHBG) secreted by the placenta during pregnancy and insulin signaling components and glucose transporter proteins (GLUTs) in the placental tissue. Design and methodsPlacental tissue was collected from full-term and non-obese [body mass index <25kg/m2] pregnant women; 10 diagnosed with GDM and 10 with normal pregnancy. We used real-time polymerase chain reaction (PCR), immunohistochemistry and western blotting to detect expression of protein and mRNA of SHBG and insulin signaling components and GLUTs in placental tissue. ResultsIn the placental tissue of non-obese women, there was a decrease in expression of SHBG protein and mRNA, with a concurrent decrease in expression of GLUT-4 protein and mRNA in women with GDM compared with normal controls. There was a decrease in GLUT-3 and insulin receptor substrate (IRS)-1 protein expression and lower IRS-2 mRNA expression was also observed in GDM placental tissue. Linear correlation analyses showed a positive correlation between SHBG and IRS-2 mRNA (P=0.038, R2=0.2178, y=0.249x+1.4208); positive correlation between SHBG and phosphatidylinositol 3-kinase (PI3K) p85α mRNA (P=0.035, R2=0.224, y=0.3506x+0.7433); positive correlation between SHBG and GLUT-4 mRNA (P=0.000, R2=0.5174, y=1.3822+1.7811x); positive correlation between IRS-2 and GLUT-4 mRNA (P=0.002, R2=0.4064, y=−0.8272+2.9592x); negative correlation between IRS-1 and PI3K p85α mRNA (P=0.005, R2=0.366, y=2.4492–0.1929x); negative correlation between IRS-1 and GLUT-3 mRNA (P=0.027, R2=0.243, y=0.9254–0.0714x); and positive correlation between IRS-2 and GLUT-1 mRNA (P=0.004, R2=0.3794, y=0.0225+0.6298x). ConclusionThe results confirm that defective receptors for insulin signal transduction and GLUT proteins are present in GDM placental tissue. Decreasing expression of SHBG may participate in regulation of insulin signaling, leading to a concomitant decrease in expression of relevant insulin signaling components in placental tissue, implying insulin resistance and eventual development of GDM.

The effect of sex hormone-binding globulin (SHBG) protein polymorphism on the levels of SHBG, testosterone, and insulin in healthy Indonesian men

Background: Sex hormone-binding globulin (SHBG) is a protein. The synthesis of SHBG protein is encoded by SHBG gene. Protein polymorphism of SHBG can occur because of a mutation of D327N exon 8 in SHBG gene. D327N mutation causes the addition of glycosylation so that molecular weight of SHBG protein increases. Protein polymorphism of SHBG is suspected to affect the levels of SHBG, testosterone, and insulin in the blood circulation. Objective: To determine the effect of protein polymorphism of SHBG on the levels of SHBG, testosterone, and insulin in healthy adult men. Materials and Methods: Serum samples were collected from 179 healthy adult men. Electrophoresis and western blotting were performed to determine the phenotype of SHBG. All subjects were divided into two groups based on SHBG phenotype; group I (normal SHBG phenotype) n = 159 subjects and group II (variant SHBG phenotype) n = 38 subjects. Result: The levels of serum SHBG, testosterone, and insulin were measured using radioimmunoassay method. The levels of SHBG, total testosterone, and free testosterone between normal SHBG phenotype do not differ with variant SHBG phenotype (p > 0.05), but insulin levels between normal SHBG phenotype compared with variant SHBG phenotype was different (p < 0.05). Conclusion: Protein polymorphisms of SHBG was not found to affect the levels of SHBG, total testosterone, and free testosterone. Protein polymorphism of SHBG was found to affect the insulin levels in the blood serum.

Association of sex hormone-binding globulin and free testosterone with mortality in men with type 2 diabetes mellitus

Low circulating testosterone levels have been associated with increased mortality in men. We hypothesized that the prognostic role of testosterone in men with type 2 diabetes mellitus (T2DM) is influenced by its carrier protein sex hormone-binding globulin (SHBG). We conducted a prospective cohort study at a tertiary referral centre. In total, 531 men with T2DM presenting to a diabetes clinic in 2004-2005 were followed prospectively until death, or July 31, 2014, and a survival analysis was performed. The main outcome measure was all cause mortality. Over a mean (S.D.) follow up of 7.6 years (2.6) 175 men (33%) died. In Cox proportional hazard models both higher SHBG (Hazard Ratio (HR) 1.012 (95% CI 1.002-1.022), P=0.02) and lower calculated free testosterone (cFT) (HR 0.995 (95% CI 0.993-0.998), P=0.001) were risk factors for all cause mortality independently of age, BMI, presence of macro- and microvascular disease, duration of T2DM, hemoglobin, renal function, insulin use, C-reactive protein and homeostatic model of insulin resistance. By contrast, the inverse association of total testosterone (TT) with mortality weakened after these adjustments (P=0.11). SHBG remained associated with mortality (P<0.001) both if substituted for or added to TT in the multivariable model. In the fully adjusted model, an increase of SHBG by 17.3 nmol/l (1 S.D.) increased mortality by 22% and a decrease in cFT by 81 pmol/l (1 S.D.) increased mortality by 45%. The association of SHBG with mortality in men with T2DM is novel. Whether SHBG acts via regulation of testosterone, has intrinsic biological roles, or is a marker of poor health requires further study.

Age-Dependent Sex Hormone-Binding Globulin Expression in Male Rat

Sex hormone binding globulin (SHBG) is known as a carrier protein, classically thought to be mainly synthesized in the liver and then secreted into the circulating system, where it binds to sex steroids with a high affinity and modulates the bioavailability of these hormones. In humans, the organs other than the liver known to produce SHBG include the brain, uterus, testis, prostate, breast and ovary, and the locally expressed SHBG is considered to play an important role in various physiological and pathological processes. A few studies of SHBG in rats were reported, but systemic SHBG studies in consideration of different organs and aging are currently missing. So we examined the SHBG expression in the brain, liver, prostate, and serum in 40 Sprague–Dawley male rats in four different groups (newborn, 2, 6, and 12 months old, respectively) with 10 in each group by immunohistochemistry, immunofluorescience microscopy, qRT-PCR, ELISA, western blotting, and laser confocal microscopy. We discovered that SHBG was increasingly expressed in all the three tissues along with age, and the SHBG protein expression was observed in the cytoplasm and membrane of neurons, hepatocyte, and prostate epithelial cells. The ELISA assay of the sera also supported an increasing SHBG level along with age. It is concluded that the locally synthesized SHBG in the liver, brain, and prostate and the circulating SHBG of male SD rats are positively associated with age, further indicating a potential role of SHBG in aging.