David H. Geller

Epigenetic mechanism underlying the development of polycystic ovary syndrome (PCOS)-like phenotypes in prenatally androgenized rhesus monkeys

The pathogenesis of polycystic ovary syndrome (PCOS) is poorly understood. PCOS-like phenotypes are produced by prenatal androgenization (PA) of female rhesus monkeys. We hypothesize that perturbation of the epigenome, through altered DNA methylation, is one of the mechanisms whereby PA reprograms monkeys to develop PCOS. Infant and adult visceral adipose tissues (VAT) harvested from 15 PA and 10 control monkeys were studied. Bisulfite treated samples were subjected to genome-wide CpG methylation analysis, designed to simultaneously measure methylation levels at 27,578 CpG sites. Analysis was carried out using Bayesian Classification with Singular Value Decomposition (BCSVD), testing all probes simultaneously in a single test. Stringent criteria were then applied to filter out invalid probes due to sequence dissimilarities between human probes and monkey DNA, and then mapped to the rhesus genome. This yielded differentially methylated loci between PA and control monkeys, 163 in infant VAT, and 325 in adult VAT (BCSVD P<0.05). Among these two sets of genes, we identified several significant pathways, including the antiproliferative role of TOB in T cell signaling and transforming growth factor-β (TGF-β) signaling. Our results suggest PA may modify DNA methylation patterns in both infant and adult VAT. This pilot study suggests that excess fetal androgen exposure in female nonhuman primates may predispose to PCOS via alteration of the epigenome, providing a novel avenue to understand PCOS in humans.

State of the Art Review: Emerging Therapies: The Use of Insulin Sensitizers in the Treatment of Adolescents with Polycystic Ovary Syndrome (PCOS)

PCOS, a heterogeneous disorder characterized by cystic ovarian morphology, androgen excess, and/or irregular periods, emerges during or shortly after puberty. Peri- and post-pubertal obesity, insulin resistance and consequent hyperinsulinemia are highly prevalent co-morbidities of PCOS and promote an ongoing state of excess androgen. Given the relationship of insulin to androgen excess, reduction of insulin secretion and/or improvement of its action at target tissues offer the possibility of improving the physical stigmata of androgen excess by correction of the reproductive dysfunction and preventing metabolic derangements from becoming entrenched. While lifestyle changes that concentrate on behavioral, dietary and exercise regimens should be considered as first line therapy for weight reduction and normalization of insulin levels in adolescents with PCOS, several therapeutic options are available and in wide use, including oral contraceptives, metformin, thiazolidenediones and spironolactone. Overwhelmingly, the data on the safety and efficacy of these medications derive from the adult PCOS literature. Despite the paucity of randomized control trials to adequately evaluate these modalities in adolescents, their use, particularly that of metformin, has gained popularity in the pediatric endocrine community. In this article, we present an overview of the use of insulin sensitizing medications in PCOS and review both the adult and (where available) adolescent literature, focusing specifically on the use of metformin in both mono- and combination therapy.

Adipose tissue insulin resistance in peripubertal girls with first-degree family history of polycystic ovary syndrome.

OBJECTIVE To assess metabolic and endocrine defects in girls genetically predisposed to polycystic ovary syndrome (PCOS). DESIGN Controlled cross-sectional study. SETTING University hospital. PATIENT(S) Nine girls, aged 8-14 years, having a first-degree relative diagnosed with PCOS (PCOSr) and 10 age-matched girls without a family history of PCOS. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Insulin sensitivity (IS(FSIVGTT)) determined by frequently sampled IV glucose tolerance testing (GTT) and insulin-induced nonesterified fatty acid (NEFA) suppression, estimated by the log-linear slope of NEFA levels during the first 20 minutes of GTT. RESULT(S) In comparison to controls, PCOSr had higher body mass index (BMI) Z-score, waist circumference, and waist-to-height ratio. Levels of the androgen 17α-hydroxyprogesterone (17-OHP) were significantly increased in PCOSr, independent of adiposity, and inversely correlated with IS(FSIVGTT). The IS(FSIVGTT) was decreased and the NEFA suppression was less steep in PCOSr compared with controls, independent of BMI and 17-OHP. The NEFA suppression was more pronounced with increasing IS(FSIVGTT), independent of adiposity. CONCLUSION(S) Girls at high risk of developing PCOS display increased adiposity and 17-OHP levels, but are mainly characterized by global insulin resistance and resistance to insulin-induced suppression of lipolysis that were independent of adiposity and 17-OHP levels. Therefore, genetic predisposition to PCOS may be related to early insulin resistance and adipocyte dysfunction.

Detecting and treating hyperlipidemia in children with type 1 diabetes mellitus: are standard guidelines applicable to this special population?*

Glaser NS, Geller DH, Haqq A, Gitelman S, Malloy M. Detecting and treating hyperlipidemia in children with type 1 diabetes mellitus: are standard guidelines applicable to this special population?

Altered glucose disposition and insulin sensitivity in peri-pubertal first-degree relatives of women with polycystic ovary syndrome

BackgroundFirst-degree relatives (FDRs) of women with PCOS are at increased risk for impaired insulin sensitivity and diabetes mellitus. Glucose tolerant FDR have evidence of insulin resistance and hyperinsulinemia prior to emergence of frank PCOS.AimTo study insulin dynamics parameters in the early adolescent FDR of women with PCOS.MethodsThis is a cross-sectional study involving 18 adolescents whose mothers or sisters had been diagnosed with PCOS and 21 healthy, age-matched control adolescents without FDR. Subjects underwent anthropometric measurements, steroid profiling and frequently sampled Intravenous Glucose Tolerance Test (IVGTT), Homeostasis Model Assessment (HOMA) index, Glucose Disposal Index (GDI), Acute Insulin Response (AIR) and Quantitative insulin sensitivity check index (QUICKI) were derived from IVGTT results.ResultsFDRs showed significantly higher mean HOMA and lower GDI. There were no differences in mean age or BMI Z-score between the cohorts. No differences in sex steroids or AIR were identified between groups.ConclusionFemale adolescent FDR of women with PCOS have higher HOMA index and lower QUICKI, reflecting altered insulin sensitivity and lower GDI reflecting poorer beta-cell function. The presence of multiple risk factors for type 2 diabetes suggests that aggressive screening of the early adolescent FDR of women with PCOS is indicated.

Ovarian and Adrenal Androgen Biosynthesis and Metabolism

The pathways of adrenal and ovarian steroid biosynthesis use the same enzymes for the initial steps of steroidogenesis but express different enzymes that convert steroid precursors to the final active products. Both the adrenal and ovary produce dehydroepiandrosterone (DHEA), the principal precursor of androgens and estrogens. The key enzyme in DHEA production is P450c17, which catalyzes both 17α-hydroxylation and 17,20-lyase activities. The 17,20-lyase activity of human P450c17 strongly favors 17-hydroxypregnenolone rather than 17-hydroxyprogesterone (17-OHP) as a substrate, producing abundant DHEA, so that most human androgens and estrogens derive from DHEA. Understanding the biochemistry of P450c17 is central to understanding the hyperandrogenism of polycystic ovary syndrome (PCOS). Rare genetic disorders of steroidogenesis provide human genetic knockout experiments of nature, yielding important information about the biosynthesis and physiological roles of steroids.

THE MOLECULAR BASIS OF ISOLATED 17,20 LYASE DEFICIENCY. • 519

Human P450c17 catalyzes the 17alpha-hydroxylation of pregnenolone to 17OH pregnenolone and of progesterone to 17alpha-OH progesterone; the same P450c17 enzyme also catalyzes 17,20 lyase activity on the same active site, converting 17OH-pregnenolone to DHEA. Rodent and porcine P450c17 also catalyze 17,20 lyase activity with delta4 substrates, converting 17OH-progesterone to delta4 androstenedione, but human P450c17 catalyzes this reaction very inefficiently, so that virtually all human C19 sex steroids are made via 17OH pregnenolone and DHEA. P450c17 is encoded by a single gene and a single species of mRNA. Many mutations of this gene have been described, but until recently all of these either entirely eliminated both 17alpha-hydroxylase and 17,20 lyase activity, or affected each activity equivalently. We have identified and characterized the first patients with P450c17 mutations that selectively ablate 17,20 lyase activity while retaining 17alpha-hydroxylase activity. Through a combination of enyzmologic experiments in transfected mammalian cells and in genetically manipulated yeast, plus a computer model of human P450c17, we have proven that the responsible mutations, R347H and R358Q lie in the redox-partner binding site of P450c17. This site, through which P450c17 interacts with P450 oxidoreductase to receive the electrons needed for catalysis, can be allosterically influenced by cytochrome b5. These two mutations have contributed substantially to our understanding of the mechanisms by which 17alpha-hydroxylase and 17,20 lyase activities are regulated independently, and thus have contributed to the study of regulated 17,20 lyase activity in adrenarche, aging, and the polycystic ovary syndrome.

Enzymologic Defect in the R347H and R358Q Mutations in P450c17 that Cause Selective 17,20-Lyase Deficiency • 425

Enzymologic Defect in the R347H and R358Q Mutations in P450c17 that Cause Selective 17,20-Lyase Deficiency • 425