Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
J Neurochem. 2012 Sep;122(6):1108-17. doi: 10.1111/j.1471-4159.2012.07865.x. Epub 2012 Aug 3.
Rapamycin-insensitive companion of TOR (Rictor) is a conserved component of target of rapamycin complex 2 (TORC2), a complex implicated in phosphorylation of a number of signal transduction-related kinases, including protein kinase Cs (PKCs) at their 'hydrophobic' site in the carboxy-terminal extension domain. In the marine mollusk, Aplysia californica, an increase in phosphorylation of the novel PKC, Apl II, at the hydrophobic site is associated with a protein synthesis-dependent increase in synaptic strength seen after continuous application of serotonin. To determine if Rictor plays a role in this increase, we cloned the Aplysia ortholog of Rictor (ApRictor). An siRNA-mediated decrease in ApRictor levels in Aplysia sensory neurons led to a decrease in the phosphorylation of PKC Apl II at the hydrophobic site suggesting a role for ApRictor in hydrophobic site phosphorylation. However, over-expression of ApRictor was not sufficient to increase phosphorylation of PKC Apl II. Continuous application of serotonin increased phosphorylation of PKC Apl II at the hydrophobic site in cultured sensory neurons, and this was blocked by Torin, which inhibits both TORC1 and TORC2. Over-expression of ApRictor did not lead to change in the magnitude of serotonin-mediated phosphorylation, but did lead to a small increase in the membrane localization of phosphorylated PKC Apl II. In conclusion, these studies implicate Rictor in phosphorylation of a novel PKC during synaptic plasticity and suggest an additional role for Rictor in regulating the localization of PKCs.
雷帕霉素不敏感的 TOR 伴侣（Rictor）是雷帕霉素靶蛋白复合物 2（TORC2）的一个保守成分，TORC2 复合物参与许多信号转导相关激酶的磷酸化，包括蛋白激酶 C（PKC）在其羧基末端延伸结构域中的“疏水性”位点。在海洋软体动物加利福尼亚海兔中，新型 PKC，Apl II 在疏水性位点的磷酸化增加与持续应用 5-羟色胺后观察到的突触强度的蛋白质合成依赖性增加有关。为了确定 Rictor 是否在此增加中起作用，我们克隆了 Aplysia 的 Rictor 同源物（ApRictor）。Aplysia 感觉神经元中 ApRictor 水平的 siRNA 介导降低导致 PKC Apl II 在疏水性位点的磷酸化减少，表明 ApRictor 在疏水性位点磷酸化中起作用。然而，ApRictor 的过表达不足以增加 PKC Apl II 的磷酸化。5-羟色胺的持续应用增加了培养感觉神经元中 PKC Apl II 在疏水性位点的磷酸化，而 Torin 抑制了 TORC1 和 TORC2，从而阻断了这一过程。ApRictor 的过表达不会导致 5-羟色胺介导的磷酸化程度发生变化，但会导致磷酸化 PKC Apl II 的膜定位略有增加。总之，这些研究表明 Rictor 在突触可塑性过程中参与了新型 PKC 的磷酸化，并表明 Rictor 在调节 PKCs 的定位方面具有额外的作用。
