Characterization of FOXO3A 419T Variant in Fragile X Premutation-Related POF

脆性 X 前突变相关 POF 中 FOXO3A 419T 变体的表征

• 批准号: 7222968
• 负责人: Stephen C Collins
• 金额: $ 2.84万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-02 至 2010-04-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7222968
• 关键词: 5' Untranslated Regions; Affect; Age; Aging; Alanine; Alleles; Amenorrhea; Amino Acids; Binding; Biological Assay; CGG repeat; Cardiovascular Diseases; Case-Control Studies; Clinical; Code; Counseling; Daughter; Development; Early Intervention; Estrogens; Event; Exhibits; Exons; FMR1; FMR1 Gene; FOXO3A gene; Failure; Female; Fertility; Follicle Stimulating Hormone; Follicular Atresia; Fragile X Mental Retardation Protein; Fragile X Premutation; Fragile X Syndrome; Future; Gene Expression; General Population; Genes; Genetic Determinism; Genetic Polymorphism; Genotype; Gonadotropins; Heterozygote; Human; Hypermethylation; In Vitro; Individual; Infertility; Inherited; Intervention; Knock-in Mouse; Knock-out; Knockout Mice; Length; Ligands; Luciferases; Mammals; Measures; Menopause; Mental Retardation; Messenger RNA; Modeling; Molecular; Molecular Genetics; Mus; Northern Blotting; Osteoporosis; Outcome; Ovarian; Patients; Phenotype; Positioning Attribute; Predisposition; Premature Ovarian Failure; RNA-Binding Proteins; Reproductive Physiology; Research; Risk; Risk Assessment; Role; Screening procedure; Serum; Sister; Staging; Testing; Transcript; Transgenic Mice; Transgenic Organisms; Translational Regulation; Translations; Trinucleotide Repeats; Untranslated Regions; Valine; Variant; Western Blotting; Woman; base; genetic association; genetic risk factor; human tissue; improved; in vivo; insight; mouse model; normal aging; novel; promoter; reproductive; reproductive function

DESCRIPTION (provided by applicant): The menopausal transition is a particularly significant stage in the aging of women, marking the end of fertility and conferring an increased risk of osteoporosis and cardiovascular disease. Genetic determinants of menopausal age can provide insight into the molecular and cellular mechanisms of menopause. One such determinant is the fragile X premutation (i.e. the presence of 55-199 CGG repeats in the 5' UTR of the fragile X mental retardation 1 (FMR1) gene), as 20% of carrier women have premature ovarian failure (POP). While patients with fragile X syndrome have no FMR1 gene expression and a complete absence of fragile X mental retardation protein (FMRP), premutation carriers have an increased level of FMR1 mRNA but a reduced level of FMRP. It is unclear how these molecular events result in premature ovarian failure. One possible mechanism to explain premutation-related POP is altered translational regulation of FOXO3A by FMRP. FOX03A is a known mRNA ligand of FMRP and has been implicated in POF by an analogous phenotype in a knockout mouse model. To determine whether polymorphisms in FOX03A associate with premutation-related POF, we sequenced the promoter and exons of FOXO3A in ten POF subjects (menopausal age <40) and ten subjects of normal menopausal age (menopausal age >46), all of whom carried the fragile X premutation. This sequencing revealed the novel 419T variant allele, in which there is a missense C->T substitution at coding position 419, in three often POF patients but in no subjects with normal age at menopause. One of the POF patients with the FOXO3A 419T variant has an affected sister and daughter who also have the 419T variant, and an unaffected sister lacking this variant, strengthening the evidence of association. We propose to conduct a case-control study to more completely characterize the association between fragile X premutation-related POF and the FOXO3A 419T variant. To define whether the association between POF and the variant is causal, we propose to create a transgenic mouse model of the FOXO3A 419T variant. Characterization of the reproductive physiology of this mouse will provide insight into how the FOXO3A 419T variant impacts fertility in humans. The 419T variant causes an alanine to valine substitution at amino acid 140, a residue conserved in mammals, and therefore is likely to alter FOXO3A function. We propose to characterize the molecular effect of the FOXO3A 419T variant. Through characterization of the FOX03A 419T variant, we can more fully understand a potentially important genetic risk factor for premature ovarian failure. The results of this research will allow women at risk for POF to be identified early, and will yield a more complete understanding of menopause and female fertility.

描述（由申请人提供）：更年期过渡是女性衰老的一个特别重要的阶段，标志着生育能力的结束，并导致骨质疏松症和心血管疾病的风险增加。绝经年龄的遗传决定因素可以深入了解绝经的分子和细胞机制。其中一个决定因素是脆弱的 X 前突变（即脆弱的 X 智力低下 1 (FMR1) 基因的 5' UTR 中存在 55-199 个 CGG 重复），因为 20% 的携带者女性患有卵巢早衰 (POP)。虽然脆性 X 综合征患者没有 FMR1 基因表达，并且完全缺乏脆性 X 智力迟钝蛋白 (FMRP)，但前突变携带者的 FMR1 mRNA 水平升高，但 FMRP 水平降低。目前尚不清楚这些分子事件如何导致卵巢早衰。解释前突变相关 POP 的一种可能机制是 FMRP 改变 FOXO3A 的翻译调控。 FOX03A 是 FMRP 的一种已知 mRNA 配体，在敲除小鼠模型中通过类似的表型表明与 POF 有关。为了确定 FOX03A 的多态性是否与前突变相关的 POF 相关，我们对 10 名 POF 受试者（绝经年龄 <40 岁）和 10 名正常绝经年龄受试者（绝经年龄 >46 岁）的 FOXO3A 启动子和外显子进行了测序，所有这些受试者都携带脆弱的 X 前突变。该测序揭示了三名常见 POF 患者中存在新的 419T 变异等位基因，其中编码位置 419 处存在错义 C->T 替换，但没有出现在绝经年龄正常的受试者中。一名携带 FOXO3A 419T 变异的 POF 患者的一位受影响的姐妹和女儿也携带 419T 变异，而一位未受影响的姐妹则缺乏这种变异，这加强了相关性的证据。我们建议进行病例对照研究，以更全面地表征脆性 X 前突变相关 POF 与 FOXO3A 419T 变体之间的关联。为了确定 POF 与该变体之间的关联是否具有因果关系，我们建议创建 FOXO3A 419T 变体的转基因小鼠模型。该小鼠生殖生理学的表征将有助于深入了解 FOXO3A 419T 变体如何影响人类的生育能力。 419T 变体导致第 140 位氨基酸（哺乳动物中保守的残基）处的丙氨酸替换为缬氨酸，因此可能会改变 FOXO3A 功能。我们建议表征 FOXO3A 419T 变体的分子效应。通过 FOX03A 419T 变体的表征，我们可以更全面地了解卵巢早衰的潜在重要遗传风险因素。这项研究的结果将使有 POF 风险的女性能够及早发现，并将更全面地了解更年期和女性生育能力。