Developmental Mechanisms of Sex-Specific Ischemic Sensitivity in Neonatal Brain

新生儿脑性别特异性缺血敏感性的发育机制

• 批准号: 8281373
• 负责人: Stephanie J Murphy
• 金额: $ 23.1万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8281373
• 关键词: Address; Animals; Astrocytes; Brain; Brain Injuries; Cells; Cerebral Ischemia; Child; Coculture Techniques; DNA Methylation; DNA Methylation Regulation; DNA Methyltransferase; DNA Modification Methylases; Data; Development; Environment; Enzymes; Epigenetic Process; Event; Exposure to; Family; Female; Figs - dietary; Gene Expression; Gene Targeting; Genes; Glucose; Gonadal Steroid Hormones; In Vitro; Ischemia; Knowledge; Link; Mediating; Mediator of activation protein; MicroRNAs; Mission; Modification; Molecular; National Institute of Neurological Disorders and Stroke; Nationalities; Neonatal; Neonatal Brain Injury; Neurons; Newborn Infant; Outcome; Oxygen; Pathway interactions; Play; Public Health; Rattus; Regulation; Research; Risk; Rodent; Role; Sex Characteristics; Shapes; Staging; Stroke; Testosterone; Time; Tissues; Work; brain cell; brain morphology; cell type; cellular development; deprivation; fetal; in vitro Model; in vivo; innovation; male; neonate; nervous system disorder; novel; overexpression; programs; response; sex; sexual dimorphism

DESCRIPTION (provided by applicant): Neonatal stroke occurs more frequently in males than females across diverse ethnic backgrounds and nationalities. However, the sex steroid environment at the time of stroke does not completely explain the sexual dimorphism observed in stroke risk and outcome in children. Preliminary data indicates that sex differences in ischemic sensitivity also extends to the cellular level, as astrocytes and neurons from male neonatal rodents are more sensitive to oxygen-glucose deprivation (OGD), an in vitro model of ischemia, than cells from female neonatal rodents. Our preliminary data suggest that the sex-specific responses of astrocytes to OGD are linked to developmental reprogramming by testosterone during sexual brain differentiation. The central hypothesis is that the developing brain can assume either a "male" or "female" basal ischemic sensitivity, with males being more sensitive, and that testosterone-induced reprogramming of astrocytes during brain differentiation shapes the development of "male" rather than "female" cellular (astrocyte and neuronal) ischemic sensitivity in neonatal brain. This proposal is innovative in that it will link testosteroe exposure during brain development to sex differences in cellular ischemic sensitivity in neonatal brain via a novel astrocyte-specific mechanism involving microRNA 29 (miR-29) mediated regulation of de novo DNA methylation enzymes and subsequent epigenetic modifications and expression of genes responsible for shaping ischemic sensitivity of astrocytes directly and of neurons indirectly. To investigate this mechanism directly, we will use an innovative approach, whereby testosterone levels during brain sexual differentiation are altered in vivo in male and female rats and then sex-stratified cultures of astrocytes and neurons derived from these rats postnatally are studied in vitro separately and in co-cultures. Aim 1 will determine if increased ischemic sensitivity of male vs. female astrocytes and neurons is due to the effects of testosterone-induced reprogramming of astrocytes during brain sexual differentiation. Hypotheses are that manipulation of testosterone levels during brain sexual differentiation will reverse sex-specific sensitivity to OGD in astrocytes and neurons. Aim 2 will determine if testosterone-induced reprogramming of astrocytes during brain sexual differentiation increases cellular (astrocyte and neuronal) ischemic sensitivity by altering expression of the miR-29 family and its target genes, de novo DNA methyltransferases 3A and 3B (DNMT3A and 3B), in astrocytes. Hypotheses are that exposure to testosterone during brain differentiation leads to increased astrocyte and neuronal sensitivity to OGD via reduced miR-29 family expression and consequent increased DNMT3A and 3B expression in astrocytes. Lentiviral overexpression or knockdown of the miR-29 family will be used to link changes in the miR-29 family to molecular and ischemic outcomes in astrocytes and neurons. The proposed work is significant as it will characterize outcomes, epigenetic events, molecular pathways and cell-specific effectors underlying the development of cellular (astrocyte and neuronal) ischemic sensitivity in male vs. female neonatal brain. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because it will address gaps in our knowledge regarding sex differences in neonatal stroke by determining if the sexual dimorphism observed in neonatal stroke is in part shaped by events early in development, specifically testosterone exposure during brain sexual differentiation. Our findings will characterize a potentially key factor in determining what aspects of cellular ischemic sensitivity in neonatal brain are modifiable vs. developmentally programmed as well as in predicting whether existing or new therapies are likely to be equally efficacious in male and female neonates. The proposed studies are also relevant to the mission of NINDS to reduce the burden of neurological diseases through research on the causes and treatment of neonatal stroke.

描述（由申请人提供）：在男性中，新生儿中风比各种种族背景和国籍的女性更频繁。但是，中风时的性类固醇环境并不能完全解释儿童中风风险和结果中观察到的性二态性。初步数据表明，缺血性敏感性的性别差异也延伸至细胞水平，因为与女性毒性啮齿动物的体外细胞相比，男性新生啮齿动物的星形胶质细胞和神经元对氧气 - 葡萄糖剥夺（OGD）的氧气更敏感。我们的初步数据表明，星形胶质细胞对OGD的性别特异性反应与性脑分化过程中睾丸激素的发育重编程有关。中心假设是，发育中的大脑可以假设“男性”或“女性”基底缺血敏感性，雄性更敏感，并且在大脑分化过程中，睾丸激素诱导的星形胶质细胞在脑分化过程中的重新编程会形成“雄性”而不是“雌性”的细胞（星形胶质细胞和神经元）缺陷脑脑中的“男性”的发展。该提案具有创新性，因为它将通过一种新型的星形胶质细胞特异性机制（MirORNA 29（MIR-29）调节，对新生儿DNA甲基化酶以及对基因的表达构成的表达和随后的表达，iSCH的表达是s象的，涉及MicroRNA 29（MIR-29）调节，因此，新生儿大脑中细胞缺血性敏感性的性别差异将其连接到新生儿大脑中的性别差异与对基因表达的介导的iSCHITION和随后对基因表达的表达的调节，将其联系起来。神经元间接。为了直接研究这种机制，我们将使用一种创新的方法，从而在男性和雌性大鼠的体内改变了脑性别分化过程中的睾丸激素水平，然后在体外和神经元的性分层培养物中衍生自这些大鼠的性别分层性培养物，并在体外和共培养中分别研究。 AIM 1将确定雄性与女性星形胶质细胞和神经元的缺血性敏感性是否增加，这是由于睾丸激素引起的在脑性分化过程中星形胶质细胞重编程的影响。假设是，在大脑性分化过程中对睾丸激素水平的操纵将逆转对星形胶质细胞和神经元中的OGD的敏感性。 AIM 2将确定睾丸激素诱导的在大脑性别分化过程中的星形胶质细胞的重编程是否会通过改变miR-29家族的表达及其靶基因的表达，从而在脑部DNA甲基转移酶3A和3B（DNMT3A和3B）（DNMT3A和3B），在脑性别分化过程中会增加细胞（星形胶质细胞和神经元）缺血敏感性。假设是，在大脑分化过程中暴露于睾丸激素会导致星形胶质细胞和神经元对OGD的敏感性通过降低的miR-29家族表达，从而增加星形胶质细胞中DNMT3A和3B表达。 MiR-29家族的慢病毒过表达或敲低将用于将MiR-29家族的变化与星形胶质细胞和神经元中的分子和缺血结果联系起来。提出的工作非常重要，因为它将表征结局，表观遗传事件，分子途径和细胞特异性效应子，这是男性与新生儿大脑中细胞（星形胶质细胞和神经元）缺血敏感性发展的基础。 公共卫生相关性：拟议的研究与公共卫生有关，因为它将通过确定在新生儿中风中观察到的性二态性是否部分是由发育早期的事件（特别是脑部性别差异期间的睾丸激素暴露）来解决的，这将解决我们有关新生儿中风性别差异的差距。我们的发现将表征在确定新生儿大脑中细胞缺血敏感性方面的哪些方面的可能性因素，并且在预测现有疗法或新疗法中是否有可能有效地在雄性和女性新生儿中同样有效。拟议的研究还与Ninds的使命有关，通过研究新生儿中风的原因和治疗来减轻神经系统疾病的负担。