Role of postsynaptic transmitter receptors in influencing presynaptic neurotransmitter identity

为了确保长距离信息传输的安全性，古希腊人和中国人在公元前3世纪开创了逆行信号，在夜间，一个塔上产生的信号火和白天产生的烟雾信号可以被远处塔上的观察者看到，然后他们点燃信号火或产生烟雾信号来确认收到信号。信号塔链可以长距离可靠地传输信号。包含一种发送逆行确认信号的机制对于现代电信的安全性非常重要。大多数关于大脑突触功能的研究都集中在突触前细胞向突触后细胞传递信息的机制上。本项目验证了非洲爪蛙（Xenopus laevis）突触后神经递质受体的逆行信号稳定突触前神经递质系统的表达的假设。该项目将揭示逆行信息信号在调节信号系统稳定性中的作用，并可能解释与突触信号稳定性缺陷相关的神经或精神疾病。该项目还将为本科生和高中生提供高级研究培训，这些学生来自目前在科学领域代表性不足的群体。本项目测试突触后递质在调节突触前递质稳定性中的作用。我们将确定潘库溴铵或curare对内源性乙酰胆碱受体的局灶性阻断是否会导致爪蟾幼虫神经肌肉接点（NMJ）突触前运动神经元（MNs）胆碱乙酰转移酶（ChAT）的逐渐丧失。初步结果表明，这与内源性递质乙酰胆碱的不稳定一致。由于这些MNs通常在发育早期短暂表达神经递质γ -氨基丁酸（GABA），我们还将在发育期间的功能获得实验中研究肌细胞中GABA受体（GABA A受体α， β和γ）的异位表达是否会导致后期突触前胆碱能MNs中GABA表达的稳定。初步数据显示，GABA出现在神经支配轴突终末和脊髓细胞体中，MN标记Hb9、ChAT和Lim3的共同表达证实了它们的主要MN身份。与谷氨酸脱羧酶67 （GAD67）和水泡GABA转运蛋白（VGAT）在这些MNs中的出现一致，肌细胞记录了GABA能微型终板电位（mEPPs）。这些结果与先前表达的递质GABA的稳定一致。为了研究突触后递质受体调节突触前递质稳定性的机制，我们将测试被认为参与形成跨突触桥的分子（Lrp4和Lfhpl4）的作用，这些分子将突触后受体与突触前稳定蛋白连接起来。抑制这些分子表达的初步结果概括了功能丧失实验的结果，并阻碍了功能获得实验的结果。突触中受体介导的逆行信号可能是维持递质表达的确认信号。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Retrograde signaling to ensure the security of message transmission over long distances was pioneered by the Greeks and the Chinese in the 3rd century B.C. Signal fires at night and smoke signals by day generated on one tower could be seen by observers on a distant tower, who then lit signal fires or generated smoke signals to acknowledge receipt of the signal. Chains of signal towers reliably transmitted signals over long distances. Inclusion of a mechanism for sending a retrograde acknowledgement signal has been important for the security of modern telecommunication. Most studies of the function of synapses in the brain have focused on the mechanisms involved in the flow of information from the presynaptic cell to the postsynaptic cell. This project tests the hypothesis that retrograde signaling from postsynaptic neurotransmitter receptors stabilizes the expression of the anterograde presynaptic neurotransmitter system in African Clawed Frogs (Xenopus laevis). This project will reveal the role of retrograde information signals in regulating the stability of the signaling system and potentially explain neurological or psychiatric disorders specifically associated with defects in the stability of synaptic signaling. This project will also provide advanced research training for undergraduate students and high school students from groups that are currently underrepresented in science.This project tests the role of postsynaptic transmitters in regulating presynaptic transmitter stability. We will determine whether loss-of-function via focal blockade of endogenous acetylcholine receptors by pancuronium or curare results in gradual loss of choline acetyl-transferase (ChAT) in presynaptic motor neurons (MNs) at the larval Xenopus neuromuscular junction (NMJ). Preliminary results show that this is the case, consistent with destabilization of the endogenous transmitter, acetylcholine. Because these MNs normally express the neurotransmitter gamma-aminobutyric acid (GABA) transiently at earlier stages of development, we will also investigate whether ectopic expression of GABA receptors (GABA A receptors alpha, beta and gamma) in myocytes in a gain-of-function experiment during development leads to stabilization of expression of GABA in presynaptic cholinergic MNs at later stages. Preliminary data show that GABA appears in innervating axon terminals and in cell bodies in the spinal cord and co-expression of the MN markers Hb9, ChAT and Lim3 confirms their primary MN identity. In line with the appearance of glutamic acid decarboxylase 67 (GAD67) and the vesicular GABA transporter (VGAT) in these MNs, GABAergic miniature endplate potentials (mEPPs) are recorded from the myocytes. These results are consistent with stabilization of the previously expressed transmitter, GABA. Investigating the mechanism by which postsynaptic transmitter receptors may regulate presynaptic transmitter stability, we will test the role of molecules thought to be involved in forming transsynaptic bridges (Lrp4 and Lfhpl4), that link postsynaptic receptors to presynaptic stabilizing proteins. Preliminary results knocking down the expression of these molecules recapitulates the loss-of-function experiments and blocks the results of the gain-of-function experiments. Receptor-mediated retrograde signaling at the synapse may be an acknowledgment signal for maintaining transmitter expression.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.