Mechanisms of Pituitary Development

描述（由申请人提供）：从全垂体功能减退（功能完全丧失）到单一激素分泌群体丧失的垂体缺陷在胎儿发育中并不罕见，最常见的单一激素缺乏症是生长激素丧失，影响1/4000的新生儿。 在鸡和其他模型系统中，在Rathke囊（垂体原基）形成之前，对早期推定腺垂体（垂体前叶）的起源和模式化机制的研究非常有限，不确定和矛盾。 发育中的鸡腺垂体是研究胚胎发生过程中外胚层原基发生的复杂时空模式事件、组织相互作用和信号机制的理想模型系统。 高分辨率的命运映射，使用多种荧光染料和延时视频显微镜，连同详细的空间和时间分析的基因表达模式，使用原位杂交（ISH），将被用来确定最终的神经/非神经起源的外胚层细胞，形成腺垂体。 然后，为了确定形成腺垂体的外胚层细胞群的规格化时间和程度，以及导致规格化的诱导组织相互作用，将在胶原凝胶中培养单个候选组织。 培养后使用一些标记基因的ISH将阐明从神经化开始胚胎中贡献组织群体的特异性状态。 然后将在胶原凝胶中培养的组织重组体用于研究导致规格化的诱导组织相互作用。 最后，将研究负责细胞向腺垂体命运的特异性的分子机制。 初步研究暗示了一种新的途径参与腺垂体细胞的特化，胰岛素/胰岛素样生长因子途径。 在分别通过ISH和免疫细胞化学对胰岛素家族成员的基因表达和蛋白分布进行详细分析之后，我们将使用功能获得和功能丧失方法进行实验，开始阐明腺垂体特异性的顺序信号事件中涉及的分子机制。

DESCRIPTION (provided by applicant): Pituitary defects ranging from panhypopituitarism (total loss of function) to loss of a single hormone secreting population are not uncommon in fetal development, with the most frequent single hormone deficiency, loss of growth hormone, affecting 1 in 4000 newborns. Studies on the origin and patterning mechanisms of the early presumptive adenohypophysis (anterior pituitary gland) in chick and other model systems, prior to formation of Rathke's pouch (the pituitary anlage), are highly limited, inconclusive and contradictory. The developing chick adenohypophysis is an excellent model system to study the complex temporal and spatial patterning events, tissue interactions and signaling mechanisms that occur in ectodermal primordia during embryogenesis. High-resolution fate mapping, using multiple fluorescent dyes and time-lapse videomicroscopy, together with detailed spatial and temporal analyses of gene expression patterns, using in situ hybridization (ISH), will be used to determine conclusively the neural/non-neural origins of the ectodermal cells that form the adenohypophysis. Then, to establish the timing and extent of specification of the populations of ectodermal cells that form the adenohypophysis, and the inductive tissue interactions that lead to specification, individual candidate tissues will be cultured in collagen gels. ISH using a number of marker genes following culture will elucidate the state of specification of the contributing tissue populations in embryos from the beginning of neuralization. Tissue recombinants cultured in collagen gels then will be used to investigate the inductive tissue interactions leading to specification. Lastly, the molecular mechanisms responsible for the specification of cells to an adenohypophyseal fate will be investigated. Preliminary studies implicate a novel pathway involved in adenohypophyseal cell specification, the Insulin/Insulin-like Growth Factor pathway. Following detailed analyses of gene expression and protein distribution, by ISH and immunocytochemistry, respectively, of Insulin family members, we will conducts experiments using both gain and loss of function approaches to begin to elucidate the molecular mechanisms involved in the sequential signaling events underlying specification of the adenohypophysis.