Regulation of the Serotonin Transporter Function by Integrins in the Mouse Brain

描述(由申请人提供)：合并抑郁障碍的存在增加了冠心病患者的发病率和死亡率。5-羟色胺能功能障碍被认为是导致情绪障碍的原因之一，也是心脏病的一个危险因素，这增加了5-羟色胺稳态改变导致神经精神疾病和心血管疾病共病的可能性。最近，我们在血小板中发现了5-羟色胺转运体(SERT)和整合素？3之间的物理和功能相互作用。虽然整合素？3对血小板功能是必不可少的，但SERT在神经元性5-羟色胺信号的调节中起着突出的作用。整合素？3多态Leu33Pro与心血管疾病有关，这是由于整合素信号和血小板聚集增强所致。这种？3变异也与自闭症患者的高5-羟色胺血症有关，因为它上调了SERT表面的表达和活性。我们的初步研究表明，整合素？3在突触前表达(作为二聚体？v？3)，在那里它与SERT物理上相关。更多的研究表明，？V？3信号的操纵直接影响SERT功能。这些发现导致了我的假设，即SERT/？V？3复合体代表突触SERT调节的一个关键和保守的方面，模拟其在血小板中的作用。本研究试图1)阐明V？3影响SERT的物理基础，2)确定V？3激活对SERT的调节作用，3)了解Leu33Pro？3编码变异对SERT功能的影响。在目标1中，我们重点利用生化和体外方法定位SERT中的？3结合结构域，为开发能够在体外干扰SERT/？V？3相互作用的小肽提供一条途径。在目标2中，我们利用小分子？V？3配体来描述？V？3激活对体外SERT功能以及体内5-羟色胺清除的影响。在目标3中，我们确定了Leu33Pro？3变体对血小板和大脑中5-羟色胺水平和SERT活性的影响。我们推测整合素Pro33？3的表达将导致血小板和脑中SERT功能的结构性升高。总之，这些研究是第一次有机会研究V？3对突触前的影响，并有助于阐明支持精神疾病和心血管疾病之间共病的途径。 与公共健康相关：拟议的项目旨在了解整合素如何使用分子和生化方法调节5-羟色胺系统。由于情绪障碍与信息处理受损有关，细胞黏附受体与抗抑郁药物治疗的主要靶点之间的关联揭示了情绪障碍影响的新机制。这项建议中详细研究的蛋白质复合体也是心境和心血管疾病的共同分子特征，并为理解这两种疾病之间的共病提供了线索。

DESCRIPTION (provided by applicant): The presence of a comorbid depressive disorder increases risk for morbidity and mortality in patients with coronary heart disease. Serotonergic dysfunction is thought to contribute to mood disorders and is also a risk factor for heart disease, raising the possibility that altered 5-HT homeostasis contribute to comorbidity between neuropsychiatric and cardiovascular disorders. Recently, we discovered a physical and functional interaction between 5-HT transporter (SERT) and integrin ?3 in platelets. While integrin ?3 is essential for platelet function, SERT plays a prominent role in the modulation of neuronal 5-HT signaling. The integrin ?3 polymorphism Leu33Pro is associated with cardiovascular disease due to enhanced integrin signaling and platelet aggregation. This ?3 variant is also associated with hyperserotonemia in autistic patients, due to its upregulation of SERT surface expression and activity. Our preliminary studies indicate that integrin ?3 is expressed presynaptically (as the dimer ?V?3), where it physically associates with SERT. Additional studies suggest that manipulation of ?V?3 signaling directly influences SERT function. These findings lead to my hypothesis that the SERT/ ?V?3 complex represents a critical and conserved facet of synaptic SERT regulation, mimicking its actions in platelets. This proposal seeks 1) to elucidate the physical basis by which ?V?3 influences SERT, 2) to establish the contribution of ?V?3-based activation to SERT regulation and 3) to understand the impact of Leu33Pro ?3 coding variation on SERT function. In Aim 1, we focus on mapping the ?3 binding domain in SERT utilizing biochemical and in vitro approaches, providing a route to the development of small peptides that can disrupt SERT/ ?V?3 interactions ex vivo. In Aim 2, we utilize small molecule ?V?3 ligands to delineate the influence of ?V?3 activation on SERT function ex vivo, as well as 5-HT clearance in vivo. In Aim 3, we determine the effects of the Leu33Pro ?3 variant on 5-HT levels and SERT activity in both platelets and in the brain. We hypothesize that the expression of integrin Pro33?3 will lead to constitutively- elevated SERT function in platelets and brain. Together, these studies represent the first opportunity to examine the presynaptic impact of ?V?3 and help elucidate pathways supporting comorbidity between mental illness and cardiovascular disease. PUBLIC HEALTH RELEVANCE: The proposed project aims to understand how integrins modulate the serotonin system using molecular and biochemical approaches. As mood disorders are associated with impaired information processing, the association between a cell adhesion receptor and the major target for antidepressant therapy reveals a novel mechanism affected by mood disorders. The protein complex studied in detail in this proposal is also a common molecular feature of mood and cardiovascular disease and provides clues to understanding the comorbidities between the two disorders.