STIM1 Controls Neuronal Ca²⁺ Signaling, mGluR1-Dependent Synaptic Transmission, and Cerebellar Motor Behavior

In central mammalian neurons, activation of metabotropic glutamate receptor type1 (mGluR1) evokes a complex synaptic response consisting of IP₃ receptor-dependent Ca²⁺ release from internal Ca²⁺ stores and a slow depolarizing potential involving TRPC3 channels. It is largely unclear how mGluR1 is linked to its downstream effectors. Here, we explored the role of stromal interaction molecule 1 (STIM1) in regulating neuronal Ca²⁺ signaling and mGluR1-dependent synaptic transmission. By analyzing mouse cerebellar Purkinje neurons, we demonstrate that STIM1 is an essential regulator of the Ca²⁺ level in neuronal endoplasmic reticulum Ca²⁺ stores. Both mGluR1-dependent synaptic potentials and IP₃ receptor-dependent Ca²⁺ signals are strongly attenuated in the absence of STIM1. Furthermore, the Purkinje neuron-specific deletion of Stim1 causes impairments in cerebellar motor behavior. Together, our results demonstrate that in the mammalian nervous system STIM1 is a key regulator of intracellular Ca²⁺ signaling, metabotropic glutamate receptor-dependent synaptic transmission, and motor coordination.