Protein phosphatase 1 isoforms, human de novo mutations and synaptic functions

可逆磷酸化是脊柱形态发生、突触形成的关键调控机制 传递、长时程增强(LTP)和记忆形成。蛋白磷酸酶1(PP1)参与了 然而，几乎一半的丝氨酸/苏氨酸磷酸化在哺乳动物细胞中的作用不同 这些过程中的Pp1亚型(Pp1α，β，γ)定义不清。 Pp1β在中枢神经系统功能中不起作用。另一方面，pp1α和pp1γ是否发挥作用 在突触中的功能从未被直接确定。通过使用条件性基因敲除小鼠模型，我们 研究发现，PP1LTP抑制突触传递和脊髓成熟，而促进β诱导和记忆 队形。另一方面，我们发现，pp1γ增加了突触传递，而pp1α起代偿作用 Pp1γ。 这一应用的主要假设是肌球蛋白磷酸酶靶向1(MYPT1)和神经肽 (NRb)分别介导Pp1β和Pp1γ/α对突触功能的不同影响。具体来说，我们将测试 我们在目标1中的假设是PP1MYPT1全酶抑制非肌肉肌球蛋白IIB介导的F-肌动蛋白 收缩抑制脊椎成熟和突触传递。我们将在目标2中确定pp1γ，in 与pp1α结合，通过与主要的NRB相互作用促进脊柱成熟，突触传递 突触支架蛋白。我们还将测试我们的预测，即pp1γ/α通过去磷酸化实现这些目标 NRB在Ser200。在目标3中，我们将检验我们的预测，即pp1β抑制LTD诱导，促进LTP诱导和 记忆形成，而Pp1γ/α起相反的作用。 我们将确定Pp1β在突触传递中的结构-突触功能关系 和可塑性，重点是pp1βC末端，其中一个人pp1β从头突变驻留。 这些研究将提供PP1异构体的信号机制和结构决定因素。 调节它们在突触功能上的不同作用。

Reversible phosphorylation is a critical regulatory mechanism for spine morphogenesis, synaptic transmission, long-term potentiation (LTP) and memory formation. Protein phosphatase 1 (PP1) contributes to almost half of the serine/threonine phosphorylation in the mammalian cells, however, the role of three different PP1 isoforms (PP1α, β, γ) in these processes is ill defined. PP1β is not believed to play a role in CNS function. On the other hand, whether PP1α and PP1γ play a role in synaptic functions have never been determined directly. By using conditional knockout mouse models, we found that PP1β inhibits synaptic transmission and spine maturation while promotes LTP induction and memory formation. On the other hand, we found that PP1γ increases synaptic transmission, with PP1α compensating PP1γ. The overarching hypothesis of this application is that myosin phosphatase targeting 1 (MYPT1) and neurabin (Nrb) mediate the distinct effects of PP1β and PP1γ/α on synaptic function, respectively. In detail, we will test our hypothesis in Aim 1 that PP1β-MYPT1 holoenzyme inhibits non-muscle myosin IIB-mediated F-actin contraction in inhibiting spine maturation and synaptic transmission. We will determine in Aim 2 that PP1γ, in combination with PP1α, promotes spine maturation, synaptic transmission by interaction with Nrb, a major synaptic scaffolding protein. We will also test our prediction that PP1γ/α achieves these via dephosphorylating Nrb at Ser200. In Aim 3 we will test our prediction that PP1β inhibits LTD induction, promotes LTP induction and memory formation while PP1γ/α plays an opposite role. We will determine the structure-synaptic function relationship in the roles of PP1β in synaptic transmission and plasticity, with an emphasis on PP1β C-termini in which one of the human PP1β de novo mutations resides. These studies will provide signaling mechanisms of, and structure determinants on, PP1 isoforms in regulating their distinct roles on synaptic functions.