Role of postsynaptic transmitter receptors in influencing presynaptic neurotransmitter identity

公元前3世纪，希腊人和中国人率先提出了确保长距离信息传输安全的逆行信号。在远处的一座塔上，观察者可以看到夜间的信号灯和白天产生的烟雾信号，然后他们点燃信号火或产生烟雾信号，以确认信号的接收。一连串的信号塔可以可靠地远距离传输信号。包含用于发送反向确认信号的机制对于现代电信的安全非常重要。大多数关于突触在大脑中的功能的研究都集中在信息从突触前细胞流向突触后细胞的机制上。该项目测试了一种假设，即来自突触后神经递质受体的逆行信号稳定了非洲爪蛙(非洲爪蛙)顺行突触前神经递质系统的表达。该项目将揭示逆行信息信号在调节信号系统稳定性方面的作用，并可能解释与突触信号稳定性缺陷具体相关的神经或精神障碍。这个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中代表性不足的群体。这个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库拉雷是否通过局部阻断内源性乙酰胆碱受体而导致幼虫神经肌肉接头(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，这种情况与内源性递质乙酰胆碱的不稳定一致。由于这些MN通常在发育早期短暂表达神经递质γ-氨基丁酸(GABA)，我们还将在发育过程中的功能获得实验中研究GABA受体(GABAA受体α、β和伽马)在心肌细胞中的异位表达是否导致突触前胆碱能MN中GABA表达在后期稳定。初步数据表明，GABA存在于支配轴突的终末和脊髓的细胞体中，MN标记HB9、ChAT和Lim3的共同表达证实了它们的初步MN身份。根据谷氨酸脱羧酶67(GAD67)和囊泡状GABA转运体(VGAT)在这些MN中的出现，从心肌细胞中记录到GABA能微型终板电位(MEPP)。这些结果与先前表达的递质GABA的稳定性一致。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梁的分子(Lrp4和Lfhpl4)的作用，这些分子将突触后受体与突触前稳定蛋白联系起来。导致这些分子表达下降的初步结果概括了功能丧失实验，并阻碍了功能获得实验的结果。受体介导的突触逆行信号可能是维持递质表达的确认信号。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.