Evaluating protocols for embryonic stem cell differentiation into insulin-secreting beta-cells using insulin II-GFP as a specific and noninvasive reporter.

Stable and full differentiation of pluripotent stem cells into functional beta-cells offers the potential to treat type I diabetes with a theoretically inexhaustible source of replacement cells. In addition to the difficulties in directed differentiation, progress toward an optimized and reliable protocol has been hampered by the complication that cultured cells will concentrate insulin from the media, thus making it difficult to tell which, if any, cells are producing insulin. To address this, we utilized a novel murine embryonic stem cell (mESC) research model, in which the green fluorescent protein (GFP) has been inserted within the C-peptide of the mouse insulinII gene (InsulinII-GFP). Using this method, cells producing insulin are easily identified. We then compared four published protocols for differentiating mESCs into beta-cells to evaluate their relative efficiency by assaying intrinsic insulin production. Cells differentiated using each protocol were easily distinguished based on culture conditions and morphology. This comparison is strengthened because all testing is performed within the same laboratory by the same researchers, thereby removing interlaboratory variability in culture, cells, or analysis. Differentiated cells were analyzed and sorted based on GFP fluorescence as compared to wild type cells. Each differentiation protocol increased GFP fluorescence but only modestly. None of these protocols yielded more than 3% of cells capable of insulin biosynthesis indicating the relative inefficiency of all analyzed protocols. Therefore, improved beta-cells differentiation protocols are needed, and these insulin II GFP cells may prove to be an important tool to accelerate this process.

Association of the -243 A-->G polymorphism of the glutamate decarboxylase 2 gene with obesity in girls with premature pubarche.

OBJECTIVE: To test the a priori hypothesis that the frequency of a single-nucleotide polymorphism (SNP) located in the promoter region of the glutamate decarboxylase 2 (GAD2) gene (-243A-->G) would be overrepresented among children with higher body mass index (BMI) values. DESIGN: Genotype-phenotype correlation study. SETTING: University-based pediatric endocrinology practice. PATIENT(S): Eighty-seven girls with PP and 70 adolescent girls with hyperandrogenism. INTERVENTION(S): Blood was obtained for genotype analysis, glucose measurement, and hormone (Delta(4)-A, insulin, 17-hydroxyprogesterone, and T) determinations. MAIN OUTCOME MEASURE(S): Frequency of this SNP in the GAD2 gene and correlation of this SNP with BMI and hormone concentrations. RESULT(S): Among the girls followed longitudinally, the presence of one or more G alleles was associated with increased BMI at both initial and recent visits and with greater BMI z score at the initial visit. No associations were found between androgen concentrations and the G-allele variant. CONCLUSION(S): Similar to the findings among French children, this SNP in the GAD2 gene was associated with increased BMI in late childhood and adolescence in this population of girls from western Pennsylvania. Additional prospective studies that replicate our findings are crucial. Verification of our findings will encourage the use of lifestyle interventions for young girls who carry the G allele.

Association of the GAA1013-->GAG polymorphism of the insulin-like growth factor-1 receptor (IGF1R) gene with premature pubarche.

OBJECTIVE: A single-nucleotide polymorphism (SNP), the G variant in codon 1013 (GAA1013-->GAG) of the insulin-like growth factor-1 (IGF-1) receptor (IGFIR) gene, has been associated with higher IGF-1 concentrations in Caucasian subjects. Because elevated serum levels of IGF-1 have been described in children with premature pubarche (PP) and in adolescent girls with hyperandrogenism, we tested the a priori hypothesis that the frequency of the A-->G variant would be overrepresented among children with PP. DESIGN: Case-control association study. SETTING: University-based pediatric endocrinology practice. PATIENT(S): Sixty-nine children (63 girls and 6 boys) with PP, 52 adolescent girls with hyperandrogenism, and 92 healthy subjects. INTERVENTION(S): Blood was obtained for genotype analysis, glucose measurement, and hormone (A, insulin, 17-hydroxyprogesterone, and T) determinations. MAIN OUTCOME MEASURE(S): Frequency of the SNP in the IGF1R gene and correlation of this SNP with hormone concentrations. RESULT(S): Distribution of the G allele was statistically significantly different between the children with PP and the healthy control subjects, independent of insulin sensitivity. CONCLUSION(S): This common SNP in the IGF1R gene may be associated with PP caused by premature adrenarche in children. Because PP has been associated with higher IGF-1 concentrations, these data suggest a potential molecular basis for prior clinical observations of elevated IGF-1 concentrations in children with PP.

Prevalence of CYP21 mutations and IRS1 variant among women with polycystic ovary syndrome and adrenal androgen excess.

OBJECTIVE: To determine whether frequencies of the mutations in the 21-hydroxylase (CYP21) gene and the G972R variant of the insulin receptor substrate-1 (IRS1) gene are increased in women with polycystic ovary syndrome (PCOS) and adrenal androgen (AA) excess. DESIGN: Prospective case-control study. SETTING: University reproductive endocrinology laboratory and outpatient clinic. PATIENT(S): Consecutive patients of non-Hispanic white race diagnosed with PCOS (n = 114) and healthy controls (n = 95). INTERVENTION(S): Blood and DNA sampling before hormonal therapy. MAIN OUTCOME MEASURE(S): Polycystic ovary syndrome patient and healthy control genotypes, with the CYP21 and IRS1 variants. RESULT(S): Fifty-four PCOS patients with (DHEAS >3000 ng/mL) and 55 without (DHEAS <2500 ng/mL) AA excess, respectively, were studied. Of 109 patients studied, 16 (14.7%) were found to be heterozygous carriers of mutations in the CYP21 gene. Of these 16, 10 (62.5%) had excessive AA secretion (i.e., excess DHEAS levels). Fifteen patients (13.8%) were found to be heterozygous carriers of the IRS1 variant; 9 (60.0%) of these 15 had excessive AA secretion. There were no significant differences in the allele frequency of CYP21 mutations or the IRS1 variant between PCOS patients with and without AA excess, and controls. None of the subjects were found to be homozygous carriers of CYP21 mutations or the IRS1 variant. Combined heterozygosity for CYP21 mutations and the IRS1 variant was limited to women with PCOS and excessive AA (n = 3). CONCLUSION(S): The G972R variant of the IRS1 gene might represent a modifier locus among women who are heterozygous carriers of CYP21 mutations, potentially increasing their risk of developing AA excess in PCOS. Nonetheless, this IRS1 variant and CYP21 mutations seem to play a limited role in the development of PCOS in the population studied.

Mutational analysis of the melanocortin-4 receptor (MC4R) gene in children with premature pubarche and adolescent girls with hyperandrogenism.

To determine if variants in the melanocortin-4 receptor (MC4R) gene are associated with premature pubarche (PP) in children and hyperandrogenism (HA) in adolescent girls, we performed single-strand conformational polymorphism (SSCP) in 75 children (69 girls/six boys) with PP, 53 adolescent girls with HA, and 95 healthy adult control subjects. DNA sequence analysis of the conformers identified by SSCP revealed variants in six patients (two silent and one missense) and in none of the control subjects.

Increased frequency of the G972R variant of the insulin receptor substrate-1 (irs-1) gene among girls with a history of precocious pubarche.

To test the hypothesis that lower sex hormone-binding globulin (SHBG) concentrations are associated with heterozygosity for the G972R variant of the IRS-1 gene among adolescent girls with a history of precocious pubarche (PP) and hyperinsulinemic ovarian hyperandrogenism.Association study. Academic research environment. Adolescent girls with a history of PP and healthy adolescent female control subjects. Determine body mass index; measure serum androgen, insulin-like growth factor (IGF)-binding protein 1, lipids, IGF-1, and SHBG concentrations; perform glucose tolerance tests; and assay for G972R variant of the IRS-1 gene. Serum androgen, IGFBP-1, and SHBG concentrations; IRS-1 genotypes.Twenty-five of 54 (45%) girls with a history of PP developed hyperinsulinemic ovarian hyperandrogenism at adolescence. Frequency of heterozygosity for G972 was 31% among girls with a history of PP, 40% among girls with hyperinsulinemic ovarian hyperandrogenism, and 19% among healthy control subjects. Sex hormone-binding globulin concentrations were lower among girls heterozygous for G972R variant. Predictors of progression from PP to hyperinsulinemic ovarian hyperandrogenism included chronological age, insulin, low-density lipoprotein cholesterol, and IGFBP-1 concentrations. The low mean SHBG concentration found among G972R carriers suggests that this variant may be a minor locus associated with development of hyperinsulinemic insulin resistance and ovarian androgen excess in girls with a history of PP.