ROLE OF BETAGLYCAN IN INHIBIN ANTAGONISM OF ACTIVIN

Betaglycan 在激活素抑制素拮抗作用中的作用

基本信息

批准号：
7537246
负责人：
WYLIE W. VALE
金额：
$ 35.02万
依托单位：
SALK INSTITUTE FOR BIOLOGICAL STUDIES
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-12-01 至 2008-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7537246
关键词：
Activins Adrenal Gland Neoplasms Affinity Anterior Pituitary Gland Binding Binding Sites Biochemical Biological Models Bone Morphogenetic Proteins Cell Line Cell physiology Cells Complex Contraceptive methods Development Disease Endocrine Follicle Stimulating Hormone Genes Grant In Vitro Inhibin-beta Subunits Knock-out Knockout Mice Mass Spectrum Analysis Mediating Mediation Mediator of activation protein Membrane Messenger RNA Modeling Molecular Mus Phenotype Pituitary Gland Play Process Production Protein Region Protein-Serine-Threonine Kinases Proteins Recombinant Inhibin A Recruitment Activity Regulation Role Signal Transduction Surface System TGF beta type III receptor Techniques Testing Transforming Growth Factor beta Variant autocrine base cell type crosslink dimer hepatic necrosis human INHA protein improved in vivo inhibin inhibin receptor member paracrine protein expression reagent testing receptor reproductive reproductive hormone research study response sertoli cell

项目摘要

Activins and certain BMPs are members of the TGF-beta superfamily that regulate FSH production by the anterior pituitary. They and their receptors also have diverse endocrine, paracrine, and autocrine actions throughout the reproductive, endocrine and other systems and play key roles in development and in pathophysiologic processes. Inhibins oppose some, but not all actions of activin and are crucial for survival as illustrated by the lethal phenotype of inhibin alpha null mice, which suffer gonadal and adrenal tumors and liver necrosis. To exert cellular effects, activins (beta-beta dimers) bind their type II receptor serine kinases (ActRII or ActRIIB) and then recruit the type I receptor serine kinase (ALK4) to form active complexes that initiate downstream signaling. Inhibins (alpha-beta dimers) compete with activins for binding to ActRII but the inhibin/ActRII complexes do not recruit ALK4 or promote signaling. Inhibins are potent functional antagonists of activin yet the relatively low affinity of inhibins compared to activin for ActRII was not in keeping with a simple competition model. Thus other components were sought and during the past grant period we identified betaglycan (TGF-beta type III receptor) as a high affinity inhibin binding protein (co-receptor) that facilitates inhibin binding to ActRII and, thereby, greatly increases the potency of inhibin to antagonize activin signaling. In model systems we have demonstrated that inhibin can antagonize responses to some BMPs. Under Aim I, these findings will be extended to test if inhibins antagonize the effects of BMPs on pituitary cells. We will continue to characterize the binding interactions between inhibins, betaglycan, and the type II receptors, ActRII, ActRIIB and BMPRII. We will identify the betaglycan residues and regions required for inhibin binding and will produce minimized soluble betaglycan forms that will be used for biochemical and structural (with Project II) studies. Identification of the critical interactive surfaces and regions of these proteins will facilitate efforts to devise strategies for modulating inhibin responses. Aim II proposes to block betaglycan or disrupt its expression in inhibin-responsive cell types including pituitary gonadotropes. In vitro and in vivo experiments will test the importance of betaglycan as an obligate mediator of inhibin actions. Finally, under Aim III we will search for additional inhibin co-receptors. We and others have evidence for the existence of multiple inhibin binding proteins including probable variants of betaglycan, which we propose to characterize. These studies will improve our understanding of the mechanisms of inhibin action and will help identify targets for the control of fertility and management of reproductive disorders.

激活素和某些BMP是TGF-BETA超家族的成员，可通过前垂体调节FSH产生。他们和他们的受体在整个生殖，内分泌和其他系统中还具有多种内分泌，旁分泌和自分泌作用，并在发育和病理生理过程中起关键作用。抑制素反对某些但并非所有的动物作用，并且对生存至关重要，如抑制素α无效小鼠的致命表型所示，后者患有性腺和肾上腺肿瘤以及肝脏坏死。发挥作用细胞效应，激活素（β-β二聚体）结合其II型丝氨酸激酶（ACTRII或ACTRIIB），然后募集I型受体丝氨酸激酶（ALK4），形成启动下游信号传导的活性复合物。抑制素（α-β二聚体）与Activins竞争与ACTRII结合，但抑制素/ACTRII复合物不募集ALK4或促进信号传导。抑制素是激活素的有效功能拮抗剂，但与Actrii的激活素相比，抑制素的亲和力相对较低，与简单的竞争模型不符。因此，寻求其他成分，在过去的赠款期间，我们将βlycan（TGF-beta III受体）确定为高亲和力抑制蛋白结合蛋白（共受体），可促进与ACTRII的抑制素结合，从而极大地增加了抑制蛋白促进激活蛋白信号的能力。在模型系统中，我们已经证明抑制剂可以拮抗对某些BMP的反应。在AIM I下，将扩展这些发现以测试抑制素是否拮抗BMP对垂体细胞的影响。我们将继续表征抑制素，βlycan和II型受体Actrii，ActriiB和BMPRII之间的结合相互作用。我们将确定抑制素结合所需的βLycan残基和区域，并将产生最小化的可溶性β-betaglycan形式，这些形式将用于生化和结构（以及项目II）研究。识别这些蛋白质的关键交互式表面和区域将有助于设计调节抑制素反应的策略。 AIM II提议阻止βlycan或破坏其在抑制素反应性细胞类型中的表达，包括垂体性腺体。体外和体内实验将测试βlycan作为抑制素作用的强制性介体的重要性。最后，在AIM III下，我们将搜索其他抑制素共受体。我们和其他人有证据表明存在多种抑制蛋白结合蛋白，包括βlycan的可能变体，我们建议这些蛋白质来表征。这些研究将提高我们对抑制素作用机制的理解，并有助于确定控制生育能力和管理生殖疾病的目标。