Proteoglycan Signaling as a New Therapeutic Target for Cocaine Addiction

描述（由申请人提供）：本修订拨款提案的目标是探索调节脑蛋白聚糖syndecan-3活性以治疗可卡因滥用的策略。蛋白聚糖如多配体蛋白聚糖-3，虽然最初被鉴定为细胞外基质（ECM）的组分，但也作为生长因子和ECM蛋白的受体和共受体发挥信号传导功能。我们观察到，syndecan-3在外侧下丘脑（LH）有一个意想不到的新的作用，限制强迫性可卡因摄入。特别是，在具体目标1中，我们将研究多配体蛋白聚糖-3胞外域脱落和可卡因摄入调节中的信号转导。多配体蛋白聚糖-3胞外域的蛋白水解切割，也称为“脱落”，在配体相互作用后诱导并终止其信号传导。为了探测胞外域脱落的功能结果，我们将使用腺相关（AAV）病毒载体来递送修饰的多配体蛋白聚糖-3构建体，包括脱落抗性多配体蛋白聚糖-3、单独的多配体蛋白聚糖-3胞外域和未修饰的多配体蛋白聚糖-3。这些研究的结果将确立抑制其配体结合胞外域的蛋白水解切割的治疗潜力。Specific Aim 2中的研究将调查syndecan-3作为替代GDNF受体在syndecan-3减少可卡因自我给药能力中的作用。为此，我们将使用AAV来修饰GDNF构建体，该GDNF构建体被设计为选择性地结合多配体蛋白聚糖-3或其典型的高亲和力受体GFR-1。Specific Aim 2的结果将为未来的研究提供信息，这些研究旨在操纵syndecan-3与其两个受体系统和信号转导伙伴之间的相互作用，以增强其信号传导活性。总之，拟议的研究将增加我们对下丘脑蛋白聚糖syndecan-3作为行为调节剂的功能的理解，并将探索可卡因滥用治疗的创新治疗策略。

DESCRIPTION (provided by applicant): The goal of this revised grant proposal is to explore strategies to modulate the activity of the brain proteoglycan syndecan-3 for the therapy of cocaine abuse. Proteoglycans like syndecan-3, while originally identified as components of the extracellular matrix (ECM), also play signaling functions as receptors and co-receptors for growth factors and ECM proteins. We observed that syndecan-3 in the lateral hypothalamus (LH) has an unexpected new role in limiting compulsive cocaine intake. In particular, in Specific Aim 1 we will investigate syndecan-3 ectodomain shedding and signal transduction in the regulation of cocaine intake. The proteolytic cleavage of syndecan-3 ectodomain, also known as "shedding" is induced after ligand interaction and terminates its signaling. To probe the functional consequence of ectodomain shedding, we will use adeno-associated (AAV) viral vectors to deliver modified syndecan-3 constructs including a shedding-resistant syndecan-3, the syndecan-3 ectodomain alone, and the unmodified syndecan-3. The results of these studies will establish the therapeutic potential of inhibiting the proteolytic cleavage of its ligand-bindig ectodomain. Studies in Specific Aim 2 will investigate the role of syndecan-3 as an alternative GDNF receptor in the ability of syndecan-3 to reduce cocaine self-administration. To this end we will use AAV to transduce modified GDNF constructs designed to bind selectively either to syndecan-3 or to its canonical high-affinity receptor GFR-¿1. The results of Specific Aim 2 will inform future studies aimed at manipulating interactions between syndecan-3 and its two receptor systems and signal transduction partners to boost its signaling activity. Together, the proposed studies will increase our understanding of the functions of the hypothalamic proteoglycan syndecan-3 as a regulator of behavior and will explore innovative therapeutic strategies for the therapy of cocaine abuse.