Departments of Pharmacology and Systems Therapeutics, Friedman Brain Institute, and System Biology Center NY, Icahn School of Medicine at Mount Sinai, New York, NY 10029.
Proc Natl Acad Sci U S A. 2013 Sep 17;110(38):15437-42. doi: 10.1073/pnas.1311783110. Epub 2013 Aug 28.
AMPA-type glutamate receptor (AMPAR) trafficking is essential for modulating synaptic transmission strength. Prior studies that have characterized signaling pathways underlying AMPAR trafficking have identified the cAMP/PKA-mediated phosphorylation of GluA1, an AMPAR subunit, as a key step in the membrane insertion of AMPAR. Inhibition of ERK impairs AMPAR membrane insertion, but the mechanism by which ERK exerts its effect is unknown. Dopamine, an activator of both PKA and ERK, induces AMPAR insertion, but the relationship between the two protein kinases in the process is not understood. We used a combination of computational modeling and live cell imaging to determine the relationship between ERK and PKA in AMPAR insertion. We developed a dynamical model to study the effects of phosphodiesterase 4 (PDE4), a cAMP phosphodiesterase that is phosphorylated and inhibited by ERK, on the membrane insertion of AMPAR. The model predicted that PKA could be a downstream effector of ERK in regulating AMPAR insertion. We experimentally tested the model predictions and found that dopamine-induced ERK phosphorylates and inhibits PDE4. This regulation results in increased cAMP levels and PKA-mediated phosphorylation of DARPP-32 and GluA1, leading to increased GluA1 trafficking to the membrane. These findings provide unique insight into an unanticipated network topology in which ERK uses PDE4 to regulate PKA output during dopamine signaling. The combination of dynamical models and experiments has helped us unravel the complex interactions between two protein kinase pathways in regulating a fundamental molecular process underlying synaptic plasticity.
AMPA 型谷氨酸受体 (AMPAR) 的转运对于调节突触传递强度至关重要。先前研究已经确定了 AMPAR 转运的信号通路，其中 cAMP/PKA 介导的 AMPAR 亚基 GluA1 的磷酸化是 AMPAR 膜插入的关键步骤。ERK 的抑制会损害 AMPAR 膜插入，但 ERK 发挥作用的机制尚不清楚。多巴胺是 PKA 和 ERK 的激活剂，可诱导 AMPAR 插入，但在这个过程中两种蛋白激酶之间的关系尚不清楚。我们使用计算建模和活细胞成像相结合的方法来确定 ERK 和 PKA 在 AMPAR 插入中的关系。我们开发了一个动态模型来研究磷酸二酯酶 4 (PDE4)，即 cAMP 磷酸二酯酶，它被 ERK 磷酸化和抑制，对 AMPAR 膜插入的影响。该模型预测 PKA 可能是 ERK 调节 AMPAR 插入的下游效应物。我们通过实验测试了模型预测，并发现多巴胺诱导的 ERK 磷酸化并抑制 PDE4。这种调节导致 cAMP 水平升高和 PKA 介导的 DARPP-32 和 GluA1 磷酸化增加，从而导致 GluA1 向膜的转运增加。这些发现为一个意想不到的网络拓扑结构提供了独特的见解，即在多巴胺信号转导过程中，ERK 利用 PDE4 来调节 PKA 的输出。动态模型和实验的结合帮助我们揭示了两种蛋白激酶通路在调节突触可塑性基础分子过程中的复杂相互作用。
