Role of Carbohydrate in the Sorting of LH and FSH

描述（由申请方提供）：人垂体促黄体生成素（LH）、促卵泡素（FSH）和促甲状腺素组成糖蛋白异源二聚体家族，由一个共同的α亚基和一个垂体特异性β亚基组成。它是唯一的β亚基，决定了每种激素的生物特异性。这些蛋白质的一个关键特征是它们独特的分泌模式。LH通过调节途径释放，即由促分泌素释放，而FSH主要组成性分泌。这些糖蛋白上的天冬酰胺连接的（N）糖蛋白是激素特异性的：LH上的末端碳水化合物是硫酸盐，而FSH是唾液酸。该提案的主要目的是解决碳水化合物结构对LH和FSH的路由和分选的作用，特别是末端硫酸盐/唾液酸与该过程的关系。这里解决的问题是末端N-连接的硫酸盐是否是分选到调节途径的信号，以及FSH的组成性释放是否与唾液酸化有关。将构建FSH β-LH β嵌合体和点突变体，以鉴定控制其独特分选模式的序列。建立的GH 3细胞系将用于筛选FSH/LH中控制调节性分泌与组成性分泌的结构特征。该细胞系来源于大鼠垂体生长激素，含有储存囊泡，对促分泌素有反应。在GH 3系中鉴定的信息性人LH和FSH变体将在缺乏内源性LH β和FSH β基因的转基因小鼠的垂体中表达，以尝试验证组织培养数据。这些实验将是至关重要的，在试图定义与细胞内运输，特别是糖蛋白激素家族的分选和包装信号所涉及的结构基序。在体内改变垂体促性腺激素的途径的能力也可以代表性腺功能障碍的一个重要模型，并可能提供一种新的方法来检查人类生殖道中的正常和最终的病理生理事件。

DESCRIPTION (provided by applicant): The human pituitary, hormones lutropin (LH), follitropin (FSH) and thyrotropin constitute a family of glycoprotein heterodimers comprised of a common alpha-subunit and a hormone-specific beta-subunit. It is the unique beta subunit that determines the biological specificity of each hormone. A critical feature of these proteins is their unique secretory patterns. LH is released through a regulated pathway, i.e, they are released by secretagogues, whereas FSH is primarily secreted constitutively. The asparagine-linked (N) otigosaccharides on these glycoproteins are hormone specific: The terminal carbohydrate on LH is sulfate, whereas for FSH it is sialic acid. The primary objective of this proposal is to address the rote of the carbohydrate structure to the routing and sorting of LH and FSH, specifically the relationship of terminal sulfate/sialic acid to this process. The question addressed here is whether terminal N-linked sulfate is a signal for sorting to the regulated pathway and constitutive release of FSH is linked to sialylation. FSHbeta-LHbeta chimeras and point mutants will be constructed to identify sequences that govern their unique sorting patterns. The established GH3 cell ling will be used to screen the structural features in FSH/LH that govern regulated vs. constitutive secretion. This cell line, which is derived from rat pituitary somatotropes, contains storage vesicles and is responsive to secretagogues. Informative human LH and FSH variants identified in the GH3 line will be expressed in pituitaries from transgenic mice lacking the endogenous LHbeta and FSHbeta genes in an attempt to verify the tissue culture data. These experiments will be critical in attempting to define the structural motifs involved with intracellular trafficking, and specifically the sorting and packaging signals for the glycoprotein hormone family. The ability to reroute the pituitary gonadotropins m vivo could also represent an important model for gonadal dysfunction and potentially provide a novel way to examine normal and ultimately pathophysiological events in the human reproductive tract.