Simpson-Golabi-Behmel Syndrome Research Articles

Extra-adrenal glucocorticoids contribute to the postprandial increase of circulating leptin in mice.

Leptin, an adipokine secreted by white adipocytes, is known for its function in regulating food intake and energy expenditure, but the mechanisms regulating its circulating levels is not fully understood. Our previous findings suggest that as yet unidentified humoral factors released from enterocytes are involved. The present study tested glucocorticoids (GCs) as candidate factors. Supplementation of corticosterone and cortisol promoted leptin production in murine adipocytes from the 3T3-L1 cell strain and human adipocytes from the Simpson Golabi-Behmel syndrome (SGBS) cell strain, respectively. These changes were observed in the absence but not presence of the GC-receptor antagonist mifepristone. The cortisol concentration in conditioned medium (CM) of human enterocyte-like Caco-2 cells was increased by phorbol-12-myristate 13-acetate and decreased by metyrapone. When SGBS adipocytes were cultured in these CMs, leptin production was positively associated with cortisol concentrations. During a 2-h refeeding after fasting, plasma leptin levels continued to increase in sham-operated mice, transiently increased at 60min in adrenalectomized mice, and were unchanged in mifepristone-administered mice. These results suggest that extra-adrenal GCs contribute to the GC-receptor signaling-dependent increase of postprandial circulating leptin, whereas further studies will be required to determine whether enterocytes participate in the GCs-mediated increase of postprandial circulating leptin.

Trail (TNF-related apoptosis-inducing ligand) induces an inflammatory response in human adipocytes

High serum concentrations of TNF-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor protein family, are found in patients with increased BMI and serum lipid levels. In a model of murine obesity, both the expression of TRAIL and its receptor (TRAIL-R) is elevated in adipose tissue. Accordingly, TRAIL has been proposed as an important mediator of adipose tissue inflammation and obesity-associated diseases. The aim of this study was to investigate if TRAIL regulates inflammatory processes at the level of the adipocyte. Using human Simpson-Golabi-Behmel syndrome (SGBS) cells as a model system, we found that TRAIL induces an inflammatory response in both preadipocytes and adipocytes. It stimulates the expression of interleukin 6 (IL-6), interleukin 8 (IL-8) as well as the chemokines monocyte chemoattractant protein-1 (MCP-1) and chemokine C-C motif ligand 20 (CCL-20) in a time- and dose-dependent manner. By using small molecule inhibitors, we found that both the NFκB and the ERK1/2 pathway are crucial for mediating the effect of TRAIL. Taken together, we identified a novel pro-inflammatory function of TRAIL in human adipocytes. Our findings suggest that targeting the TRAIL/TRAIL-R system might be a useful strategy to tackle obesity-associated adipose tissue inflammation.

SGBS cells as a model of human adipocyte browning: A comprehensive comparative study with primary human white subcutaneous adipocytes

The Simpson Golabi Behmel Syndrome (SGBS) pre-adipocyte cell strain is widely considered to be a representative in vitro model of human white pre-adipocytes. A recent study suggested that SGBS adipocytes exhibit an unexpected transient brown phenotype. Here, we comprehensively examined key differences between SGBS adipocytes and primary human white subcutaneous (PHWSC) adipocytes. RNA-Seq analysis revealed that extracellular matrix (ECM)-receptor interaction and metabolic pathways were the top two KEGG pathways significantly enriched in SGBS adipocytes, which included positively enriched mitochondrial respiration and oxidation pathways. Compared to PHWSC adipocytes, SGBS adipocytes showed not only greater induction of adipogenic gene expression during differentiation but also increased levels of UCP1 mRNA and protein expression. Functionally, SGBS adipocytes displayed higher ISO-induced basal leak respiration and overall oxygen consumption rate, along with increased triglyceride accumulation and insulin-stimulated glucose uptake. In conclusion, we confirmed that SGBS adipocytes, which are considered of white adipose tissue origin can shift towards a brown/beige adipocyte phenotype. These differences indicate SGBS cells may help to identify mechanisms leading to browning, and inform our understanding for the use of SGBS vis-à-vis primary human subcutaneous adipocytes as a human white adipocyte model, guiding the selection of appropriate cell models in future metabolic research.

Collagen beta (1-O) galactosyltransferase 1 (GLT25D1) is required for the secretion of high molecular weight adiponectin and affects lipid accumulation.

Secretion of high molecular weight (HMW) adiponectin is dependent on post-translational modification (PTM) of conserved lysines in the collagenous domain. The present study aims to characterize the enzymes responsible for the PTM of conserved lysines which leads to HMW adiponectin secretion, and to define its significance in relation to obesity. Collagen beta (1-O) galactosyltransferase 1 (GLT25D1) was knocked down in HEK cells modified for the stable expression of adiponectin (adiponectin expressing human embryonic kidney cells, Adipo-HEK) as well as in Simpson Golabi-Behmel-Syndrome (SGBS) adipocytes. Knockdown of GLT25D1 caused a significant decrease in HMW adiponectin in Adipo-HEK cells with no change in total adiponectin. Knockdown in the SGBS cells caused an increase in lipid accumulation yet inhibited adipogenesis. Co-immunoprecipitation with adiponectin and mass spectrometry showed that adiponectin formed a protein complex with lysyl hydroxylase 3 (LH3) and GLT25D1. Transient overexpression of GLT25D1 showed that the intracellular retention of LH3 was dependent on GLT25D1. To determine whether changes in GLT25D1 were significant in obesity, mice were fed a standard chow or high-fat diet (HFD) for 5 weeks. GLT25D1 was significantly decreased in mice fed HFD which coincided with a decrease in HMW adiponectin. We conclude that GLT25D1 regulates HMW adiponectin secretion and lipid accumulation, consistent with changes in mice after high-fat feeding. These results suggest a novel function of GLT25D1 leading to decreased HMW adiponectin secretion in early obesity.

First reported case of Simpson–Golabi–Behmel syndrome in a female fetus diagnosed prenatally with chromosomal microarray

Key Clinical MessageSimpson–Golabi–Behmel syndrome (SGBS) is a rare X‐linked syndrome. Female carriers may have mild manifestations. Macrosomia, polyhydramnios, and kidney and urinary tract anomalies are common findings in male fetuses. We present the first case of a severely affected female fetus with stigmata of SGBS and a deletion involving the GPC3 gene.

MiR-146a-mediated suppression of the inflammatory response in human adipocytes.

The obesity-associated inflammation of white adipose tissue (WAT) is one of the factors leading to the development of related diseases such as insulin resistance and liver steatosis. Recently, microRNAs (miRNAs) were identified as important regulators of WAT functions. Herein, we cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes with macrophage-conditioned medium (MacCM) and performed an Affimetrix miRNA array to identify miRNAs differentially expressed under inflammatory conditions. We identified 24 miRNAs differentially expressed upon inflammation in human adipocytes and miR-146a was the most up-regulated miRNA species. In subcutaneous WAT, miR-146a was elevated in both human and murine obesity. Transfection of miR-146a mimics prevented the MacCM-induced inflammatory response in SGBS adipocytes as seen by reduced levels of IL-8 and MCP-1 mRNA and protein. We identified IRAK1 and TRAF6 as targets of miR-146a in human adipocytes and detected a reduced inflammation-induced activation of JNK and p38 upon miR-146a transfection. Taken together, we could show that miR-146a reduces the inflammatory response in human adipocytes. In a negative feedback loop miR-146a might contribute to the regulation of inflammatory processes in WAT and possibly prevent an overwhelming inflammatory response.

Clozapine modifies the differentiation program of human adipocytes inducing browning.

Administration of second-generation antipsychotic drugs (SGAs) often leads to weight gain and consequent cardio-metabolic side effects. We observed that clozapine but not six other antipsychotic drugs reprogrammed the gene expression pattern of differentiating human adipocytes ex vivo, leading to an elevated expression of the browning marker gene UCP1, more and smaller lipid droplets and more mitochondrial DNA than in the untreated white adipocytes. Laser scanning cytometry showed that up to 40% of the differentiating single primary and Simpson–Golabi–Behmel syndrome (SGBS) adipocytes had the characteristic morphological features of browning cells. Furthermore, clozapine significantly upregulated ELOVL3, CIDEA, CYC1, PGC1A and TBX1 genes but not ZIC1 suggesting induction of the beige-like and not the classical brown phenotype. When we tested whether browning induced by clozapine can be explained by its known pharmacological effect of antagonizing serotonin (5HT) receptors, it was found that browning cells expressed 5HT receptors 2A, 1D, 7 and the upregulation of browning markers was diminished in the presence of exogenous 5HT. Undifferentiated progenitors or completely differentiated beige or white adipocytes did not respond to clozapine administration. The clozapine-induced beige cells displayed increased basal and oligomycin-inhibited (proton leak) oxygen consumption, but these cells showed a lower response to cAMP stimulus as compared with control beige adipocytes indicating that they are less capable to respond to natural thermogenic anti-obesity cues. Our data altogether suggest that novel pharmacological stimulation of these masked beige adipocytes can be a future therapeutic target for the treatment of SGA-induced weight gain.

Accumulation of CD11c+CD163+ Adipose Tissue Macrophages through Upregulation of Intracellular 11β-HSD1 in Human Obesity.

Adipose tissue (AT) macrophages (ATMs) are key players for regulation of AT homeostasis and obesity-related metabolic disorders. However, the phenotypes of human ATMs and regulatory mechanisms of their polarization have not been clearly described. In this study, we investigated human ATMs in both abdominal visceral AT and s.c. AT and proposed an 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1)-glucocorticoid receptor regulatory axis that might dictate M1/M2 polarization in ATMs. The accumulation of CD11c+CD163+ ATMs in both visceral AT and s.c. AT of obese individuals was confirmed at the cellular level and was found to be clearly correlated with body mass index and production of reactive oxygen species. Using our in vitro system where human peripheral blood monocytes (hPBMs) were cocultured with Simpson-Golabi-Behmel syndrome adipocytes, M1/M2 polarization was found to be dependent on 11β-HSD1, an intracellular glucocorticoid reactivating enzyme. Exposure of hPBMs to cortisol-induced expression of CD163 and RU-486, a glucocorticoid receptor antagonist, significantly abrogated CD163 expression through coculture of mature adipocytes with hPBMs. Moreover, 11β-HSD1 was expressed in crown ATMs in obese AT. Importantly, conditioned medium from coculture of adipocytes with hPBMs enhanced proliferation of human breast cancer MCF7 and MDA-MB-231 cells. In summary, the phenotypic switch of ATMs from M2 to mixed M1/M2 phenotype occurred through differentiation of adipocytes in obese individuals, and upregulation of intracellular 11β-HSD1 might play a role in the process.

Simpson–Golabi–Behmel syndrome in a female: A case report and an unsolved issue

Simpson-Golabi-Behmel syndrome is an X-linked recessive overgrowth condition caused by alterations in GPC3 gene, encoding for the cell surface receptor glypican 3, whose clinical manifestations in affected males are well known. Conversely, there is little information regarding affected females, with very few reported cases, and a clinical definition of this phenotype is still lacking. In the present report we describe an additional case, the first to receive a primary molecular diagnosis based on strong clinical suspicion. Possible explanations for full clinical expression of X-linked recessive conditions in females include several mechanisms, such as skewed X inactivation or homozygosity/compound heterozygosity of the causal mutation. Both of these were excluded in our case. Given that the possibility of full expression of SGBS in females is now firmly established, we recommend that GPC3 analysis be performed in all suggestive female cases. © 2016 Wiley Periodicals, Inc.

Loss-of-function mutations and global rearrangements in GPC3 in patients with Simpson-Golabi-Behmel syndrome.

Simpson–Golabi–Behmel syndrome is a congenital malformation syndrome associated with mutations in GPC3, which is located in the Xq26 region. Three new loss-of-function mutations and a global X-chromosome rearrangement involving GPC3 were identified. A female sibling of the patient, who presented with a cleft palate and hepatoblastoma, carries the same chromosomal rearrangement and a paradoxical pattern of X-chromosome inactivation. These findings support variable GPC3 alterations, with a possible mechanism in female patients.

TRAIL (TNF-related apoptosis-inducing ligand) inhibits human adipocyte differentiation via caspase-mediated downregulation of adipogenic transcription factors.

Tumor necrosis factor-α (TNFα) and other ligands of the TNF superfamily are potent regulators of adipose tissue metabolism and play a crucial role in the obesity-induced inflammation of adipose tissue. Adipose tissue expression levels of TRAIL (TNF-related apoptosis-inducing ligand) and its receptor were shown to be upregulated by overfeeding and decreased by fasting in mice. In the present study we aimed to elucidate the impact of TRAIL on adipogenesis. To this end, human Simpson-Golabi-Behmel syndrome (SGBS) preadipocytes as well as stromal-vascular cells isolated from human white adipose tissue were used as model systems. Human recombinant TRAIL inhibited adipogenic differentiation in a dose-dependent manner. It activated the cleavage of caspase-8 and -3, which in turn resulted in a downregulation of the key adipogenic transcription factors C/EBPα, C/EBPδ, and PPARγ. The effect was completely blocked by pharmacological or genetic inhibition of caspases. Taken together we discovered a so far unrecognized function of TRAIL in the regulation of adipogenesis. Targeting the TRAIL/TRAIL receptor system might provide a novel strategy to interfere with adipose tissue homeostasis.

A role for the metalloprotease invadolysin in insulin signaling and adipogenesis.

Invadolysin is a novel metalloprotease conserved amongst metazoans that is essential for life in Drosophila. We previously showed that invadolysin was essential for the cell cycle and cell migration, linking to metabolism through a role in lipid storage and interaction with mitochondrial proteins. In this study we demonstrate that invadolysin mutants exhibit increased autophagy and decreased glycogen storage - suggestive of a role for invadolysin in insulin signaling in Drosophila. Consistent with this, effectors of insulin signaling were decreased in invadolysin mutants. In addition, we discovered that invadolysin was deposited on newly synthesized lipid droplets in a PKC-dependent manner. We examined two in vitro models of adipogenesis for the expression and localization of invadolysin. The level of invadolysin increased during both murine 3T3-L1 and human Simpson-Golabi-Behmel syndrome (SGBS), adipogenesis. Invadolysin displayed a dynamic localization to lipid droplets over the course of adipogenesis, which may be due to the differential expression of distinct invadolysin variants. Pharmacological inhibition of adipogenesis abrogated the increase in invadolysin. In summary, our results on in vivo and in vitro systems highlight an important role for invadolysin in insulin signaling and adipogenesis.

Prenatal diagnosis of Simpson-Golabi-Behmel syndrome.

Simpson-Golabi-Behmel syndrome (SGBS) is an overgrowth syndrome and it is usually diagnosed postnatally, on the basis of phenotype. Prenatal ultrasonography may show fetal alterations, but they are not pathognomonic and most of them are frequently detectable only from the 20th week of gestation. Nevertheless, early diagnosis is important to avoid neonatal complications and make timely and informed decisions about the pregnancy. We report on four fetuses from two unrelated families, in whom the application of whole exome sequencing and array-CGH allowed the identification of GPC3 alterations causing SGBS. The careful follow up of pregnancies and more sophisticated analysis of ultrasound findings led to the identification of early prenatal alterations, which will improve the antenatal diagnosis of SGBS. © 2016 Wiley Periodicals, Inc.

Redundant roles of the phosphatidate phosphatase family in triacylglycerol synthesis in human adipocytes.

Aims/hypothesisIn mammals, the evolutionary conserved family of Mg2+-dependent phosphatidate phosphatases (PAP1), involved in phospholipid and triacylglycerol synthesis, consists of lipin-1, lipin-2 and lipin-3. While mutations in the murine Lpin1 gene cause lipodystrophy and its knockdown in mouse 3T3-L1 cells impairs adipogenesis, deleterious mutations of human LPIN1 do not affect adipose tissue distribution. However, reduced LPIN1 and PAP1 activity has been described in participants with type 2 diabetes. We aimed to characterise the roles of all lipin family members in human adipose tissue and adipogenesis.MethodsThe expression of the lipin family was analysed in adipose tissue in a cross-sectional study. Moreover, the effects of lipin small interfering RNA (siRNA)-mediated depletion on in vitro human adipogenesis were assessed.ResultsAdipose tissue gene expression of the lipin family is altered in type 2 diabetes. Depletion of every lipin family member in a human Simpson–Golabi–Behmel syndrome (SGBS) pre-adipocyte cell line, alters expression levels of adipogenic transcription factors and lipid biosynthesis genes in early stages of differentiation. Lipin-1 knockdown alone causes a 95% depletion of PAP1 activity. Despite the reduced PAP1 activity and alterations in early adipogenesis, lipin-silenced cells differentiate and accumulate neutral lipids. Even combinatorial knockdown of lipins shows mild effects on triacylglycerol accumulation in mature adipocytes.Conclusions/interpretationOverall, our data support the hypothesis of alternative pathways for triacylglycerol synthesis in human adipocytes under conditions of repressed lipin expression. We propose that induction of alternative lipid phosphate phosphatases, along with the inhibition of lipid hydrolysis, contributes to the maintenance of triacylglycerol content to near normal levels.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-016-4018-0) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

Quercetin Impacts Expression of Metabolism- and Obesity-Associated Genes in SGBS Adipocytes.

Obesity is characterized by the rapid expansion of visceral adipose tissue, resulting in a hypoxic environment in adipose tissue which leads to a profound change of gene expression in adipocytes. As a consequence, there is a dysregulation of metabolism and adipokine secretion in adipose tissue leading to the development of systemic inflammation and finally resulting in the onset of metabolic diseases. The flavonoid quercetin as well as other secondary plant metabolites also referred to as phytochemicals have anti-oxidant, anti-inflammatory, and anti-diabetic effects known to be protective in view of obesity-related-diseases. Nevertheless, its underlying molecular mechanism is still obscure and thus the focus of this study was to explore the influence of quercetin on human SGBS (Simpson Golabi Behmel Syndrome) adipocytes’ gene expression. We revealed for the first time that quercetin significantly changed expression of adipokine (Angptl4, adipsin, irisin and PAI-1) and glycolysis-involved (ENO2, PFKP and PFKFB4) genes, and that this effect not only antagonized but in part even overcompensated the effect mediated by hypoxia in adipocytes. Thus, these results are explained by the recently proposed hypothesis that the protective effect of quercetin is not solely due to its free radical-scavenging activity but also to a direct effect on mitochondrial processes, and they demonstrate that quercetin might have the potential to counteract the development of obesity-associated complications.

Insulin/glucose induces natriuretic peptide clearance receptor in human adipocytes: a metabolic link with the cardiac natriuretic pathway.

Cardiac natriuretic peptides (NP) are involved in cardiorenal regulation and in lipolysis. The NP activity is largely dependent on the ratio between the signaling receptor NPRA and the clearance receptor NPRC. Lipolysis increases when NPRC is reduced by starving or very-low-calorie diet. On the contrary, insulin is an antilipolytic hormone that increases sodium retention, suggesting a possible functional link with NP. We examined the insulin-mediated regulation of NP receptors in differentiated human adipocytes and tested the association of NP receptor expression in visceral adipose tissue (VAT) with metabolic profiles of patients undergoing renal surgery. Differentiated human adipocytes from VAT and Simpson-Golabi-Behmel Syndrome (SGBS) adipocyte cell line were treated with insulin in the presence of high-glucose or low-glucose media to study NP receptors and insulin/glucose-regulated pathways. Fasting blood samples and VAT samples were taken from patients on the day of renal surgery. We observed a potent insulin-mediated and glucose-dependent upregulation of NPRC, through the phosphatidylinositol 3-kinase pathway, associated with lower lipolysis in differentiated adipocytes. No effect was observed on NPRA. Low-glucose medium, used to simulate in vivo starving conditions, hampered the insulin effect on NPRC through modulation of insulin/glucose-regulated pathways, allowing atrial natriuretic peptide to induce lipolysis and thermogenic genes. An expression ratio in favor of NPRC in adipose tissue was associated with higher fasting insulinemia, HOMA-IR, and atherogenic lipid levels. Insulin/glucose-dependent NPRC induction in adipocytes might be a key factor linking hyperinsulinemia, metabolic syndrome, and higher blood pressure by reducing NP effects on adipocytes.

Therapeutic potential of the dual peroxisome proliferator activated receptor (PPAR)α/γ agonist aleglitazar in attenuating TNF-α-mediated inflammation and insulin resistance in human adipocytes

Adipose tissue inflammation is a mechanistic link between obesity and its related sequelae, including insulin resistance and type 2 diabetes. Dual ligands of peroxisome proliferator activated receptor (PPAR)α and γ, combining in a single molecule the metabolic and inflammatory-regulatory properties of α and γ agonists, have been proposed as a promising therapeutic strategy to antagonize adipose tissue inflammation.Here we investigated the effects of the dual PPARα/γ agonist aleglitazar on human adipocytes challenged with inflammatory stimuli. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were treated with aleglitazar or ⿿ for comparison ⿿ the selective agonists for PPARα or γ fenofibrate or rosiglitazone, respectively, for 24h before stimulation with TNF-α. Aleglitazar, at concentrations as low as 10nmol/L, providing the half-maximal transcriptional activation of both PPARα and PPARγ, reduced the stimulated expression of several pro-inflammatory mediators including interleukin (IL)-6, the chemokine CXC-L10, and monocyte chemoattractant protein (MCP)-1. Correspondingly, media from adipocytes treated with aleglitazar reduced monocyte migration, consistent with suppression of MCP-1 secretion. Under the same conditions, aleglitazar also reversed the TNF-α-mediated suppression of insulin-stimulated ser473 Akt phosphorylation and decreased the TNF-α-induced ser312 IRS1 phosphorylation, two major switches in insulin-mediated metabolic activities, restoring glucose uptake in insulin-resistant adipocytes. Such effects were similar to those obtainable with a combination of single PPARα and γ agonists.In conclusion, aleglitazar reduces inflammatory activation and dysfunction in insulin signaling in activated adipocytes, properties that may benefit diabetic and obese patients. The effect of aleglitazar was consistent with dual PPARα and γ agonism, but with no evidence of synergism.

Importance of adipocyte cyclooxygenase‐2 and prostaglandin E 2 ‐prostaglandin E receptor 3 signaling in the development of obesity‐induced adipose tissue inflammation and insulin resistance

We examined the involvement of adipocyte cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2)-prostaglandin E receptor (EP)3-mediated signaling during hypertrophy and hypoxia in the development of obesity-associated adipose tissue (AT) inflammation and insulin resistance. The experiments were conducted with high-fat diet (HFD)-induced obese rats, db/db mice, human subjects, and 3T3-L1 and the human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes; the groups were treated with selective inhibitors of COX-2 [celecoxib 30 mg/kg, half maximal inhibitory concentration (IC50) ≈ 0.04 µM] and EP3 (L-798106 100 µg/kg, IC50 ≈ 0.5 µM) or a short interfering RNA. There were strong, positive correlations between adipocyte COX-2 and EP3 gene expressions and the AT TNF-α and monocyte chemotactic protein-1 contents and the homeostatic model assessment for insulin resistance in HFD-induced obese rats, as well as body mass index in human subjects. Treatment with COX-2 and EP3 inhibitors significantly reversed AT inflammatory gene and protein expressions (-50%) and impaired glucose and insulin tolerance in db/db mice. COX-2 inhibition diminished the chemotaxis of adipocytes isolated from HFD rats to macrophages and T cells. Targeting inhibition of adipocyte COX-2 and EP3 during hypertrophy and hypoxia reversed the release of the augmented proinflammatory adipokines and the diminished adiponectin and also suppressed NF-κB and hypoxia-inducible factor-1α transcription activation. These findings suggest that adipocyte COX-2 PGE2-EP3-mediated signaling is crucially involved in the development of obesity-associated AT inflammation and insulin resistance.-Chan, P.-C., Hsiao, F.-C., Chang, H.-M., Wabitsch, M., Hsieh, P. S. Importance of adipocyte cyclooxygenase-2 and prostaglandin E2-prostaglandin E receptor 3 signaling in the development of obesity-induced adipose tissue inflammation and insulin resistance.

A clinical and molecular investigation of two South African families with Simpson-Golabi-Behmel syndrome.

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked recessive overgrowth syndrome manifesting primarily in boys and characterised by macrosomia, distinctive facial features and multiple congenital abnormalities. Although this rare condition is thought to be underdiagnosed, making a diagnosis is important as affected boys have a 7.5% risk of developing visceral tumours and surveillance is warranted. Mutations in GPC3 are found in up to 70% of boys affected with SGBS. A clinical and molecular investigation of two boys with SGBS, probands B and S, and their mothers. Documentation of the clinical phenotype could assist with diagnosis in affected boys and will lead to early initiation of tumour surveillance. Hospital folders were reviewed and clinical consultations arranged for both probands and their mothers. Molecular investigations initially searched for whole-exon deletions in GPC3 followed by gene sequencing. The clinical phenotype of both probands was consistent with that previously reported in the literature. The main features pointing towards the diagnosis were macrosomia, coarse facial features and macroglossia with a midline groove in the tongue. Proband B developed a Wilms tumour. He was found to have a novel mutation causing a premature stop codon. This research represents the first published report of SGBS in South Africa. Early recognition and confirmation of this condition is important in order to institute tumour surveillance and assist families with accurate recurrence risks.

Weight loss-induced stress in subcutaneous adipose tissue is related to weight regain.

Initial successful weight loss is often followed by weight regain after the dietary intervention. Compared with lean people, cellular stress in adipose tissue is increased in obese subjects. However, the relation between cellular stress and the risk for weight regain after weight loss is unclear. Therefore, we determined the expression levels of stress proteins during weight loss and weight maintenance in relation to weight regain. In vivo findings were compared with results from in vitro cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. In total, eighteen healthy subjects underwent an 8-week diet programme with a 10-month follow-up. Participants were categorised as weight maintainers or weight regainers (WR) depending on their weight changes during the intervention. Abdominal subcutaneous adipose tissue biopsies were obtained before and after the diet and after the follow-up. In vitro differentiated SGBS adipocytes were starved for 96 h with low (0·55 mm) glucose. Levels of stress proteins were determined by Western blotting. WR showed increased expressions of β-actin, calnexin, heat shock protein (HSP) 27, HSP60 and HSP70. Changes of β-actin, HSP27 and HSP70 are linked to HSP60, a proposed key factor in weight regain after weight loss. SGBS adipocytes showed increased levels of β-actin and HSP60 after 96 h of glucose restriction. The increased level of cellular stress proteins in the adipose tissue of WR probably resides in the adipocytes as shown by in vitro experiments. Cellular stress accumulated in adipose tissue during weight loss may be a risk factor for weight regain.