Dohn Michael R, Kooker Christopher G, Bastarache Lisa, Jessen Tammy, Rinaldi Capria, Varney Seth, Mazalouskas Matthew D, Pan Hope, Oliver Kendra H, Velez Edwards Digna R, Sutcliffe James S, Denny Joshua C, Carneiro Ana M D
Departments of Pharmacology.
Biomedical Informatics and Medicine.
J Neurosci. 2017 Nov 15;37(46):11271-11284. doi: 10.1523/JNEUROSCI.1482-17.2017. Epub 2017 Oct 16.
Engagement of integrins by the extracellular matrix initiates signaling cascades that drive a variety of cellular functions, including neuronal migration and axonal pathfinding in the brain. Multiple lines of evidence link the gene encoding the integrin β3 subunit with the serotonin (5-HT) system, likely via its modulation of the 5-HT transporter (SERT). The coding polymorphism Leu33Pro (rs5918, Pl) produces hyperactive αvβ3 receptors that influence whole-blood 5-HT levels and may influence the risk for autism spectrum disorder (ASD). Using a phenome-wide scan of psychiatric diagnoses, we found significant, male-specific associations between the Pro33 allele and attention-deficit hyperactivity disorder and ASDs. Here, we used knock-in (KI) mice expressing an variant that phenocopies the human Pro33 variant to elucidate the consequences of constitutively enhanced αvβ3 signaling to the 5-HT system in the brain. KI mice displayed deficits in multiple behaviors, including anxiety, repetitive, and social behaviors. Anatomical studies revealed a significant decrease in 5-HT synapses in the midbrain, accompanied by decreases in SERT activity and reduced localization of SERTs to integrin adhesion complexes in synapses of KI mice. Inhibition of focal adhesion kinase (FAK) rescued SERT function in synapses of KI mice, demonstrating that constitutive active FAK signaling downstream of the Pro32Pro33 integrin αvβ3 suppresses SERT activity. Our studies identify a complex regulation of 5-HT homeostasis and behaviors by integrin αvβ3, revealing an important role for integrins in modulating risk for neuropsychiatric disorders. The integrin β3 Leu33Pro coding polymorphism has been associated with autism spectrum disorders (ASDs) within a subgroup of patients with elevated blood 5-HT levels, linking integrin β3, 5-HT, and ASD risk. We capitalized on these interactions to demonstrate that the Pro33 coding variation in the murine integrin β3 recapitulates the sex-dependent neurochemical and behavioral attributes of ASD. Using state-of-the-art techniques, we show that presynaptic 5-HT function is altered in these mice, and that the localization of 5-HT transporters to specific compartments within the synapse, disrupted by the integrin β3 Pro33 mutation, is critical for appropriate reuptake of 5-HT. Our studies provide fundamental insight into the genetic network regulating 5-HT neurotransmission in the CNS that is also associated with ASD risk.
细胞外基质与整合素的结合会引发信号级联反应，从而驱动多种细胞功能，包括大脑中的神经元迁移和轴突导向。多条证据表明，编码整合素β3亚基的基因与血清素（5-HT）系统相关联，可能是通过其对5-HT转运体（SERT）的调节来实现的。编码多态性Leu33Pro（rs5918，Pl）会产生过度活跃的αvβ3受体，影响全血5-HT水平，并可能影响自闭症谱系障碍（ASD）的风险。通过对精神疾病诊断进行全表型扫描，我们发现Pro33等位基因与注意力缺陷多动障碍和ASD之间存在显著的、男性特异性的关联。在此，我们使用表达一种模拟人类Pro33变体的变体的敲入（KI）小鼠，以阐明大脑中αvβ3信号持续增强对5-HT系统的影响。KI小鼠在多种行为上表现出缺陷，包括焦虑、重复和社交行为。解剖学研究显示，中脑5-HT突触显著减少，同时KI小鼠突触中SERT活性降低，SERT向整合素黏附复合物的定位减少。抑制粘着斑激酶（FAK）可挽救KI小鼠突触中的SERT功能，表明Pro32Pro33整合素αvβ3下游的组成型活性FAK信号抑制SERT活性。我们的研究确定了整合素αvβ3对5-HT稳态和行为的复杂调节，揭示了整合素在调节神经精神疾病风险中的重要作用。整合素β3 Leu33Pro编码多态性与血液5-HT水平升高的患者亚组中的自闭症谱系障碍（ASD）相关联，将整合素β3、5-HT和ASD风险联系起来。我们利用这些相互作用来证明，小鼠整合素β3中的Pro33编码变异概括了ASD的性别依赖性神经化学和行为特征。使用最先进的技术，我们表明这些小鼠的突触前5-HT功能发生了改变，并且整合素β3 Pro33突变破坏了5-HT转运体在突触内特定区域的定位，这对5-HT的适当再摄取至关重要。我们的研究为调节中枢神经系统中5-HT神经传递的遗传网络提供了基本见解，该网络也与ASD风险相关。
