PRRT2 deficiency induces paroxysmal kinesigenic dyskinesia by influencing synaptic function in the primary motor cortex of rats.

Proline-rich transmembrane protein 2 (PRRT2) was identified as the causative gene of paroxysmal kinesigenic choreoathetosis (PKC) as well as various other neurological diseases. However, the molecular mechanisms of how mutant PRRT2 leads to abnormal synaptic function and triggers PKC are still obscure. We generated a Prrt2 truncated mutant rat model which shows spontaneous PKC-like attacks with a relative low frequency as well as increased susceptibility to pentylenetetrazol (PTZ)-induced seizures. We demonstrate that PRRT2 is expressed on both pre- and post-synaptic membranes in the M1 cortex. PRRT2 negatively regulates SNARE complex assembly through interaction with SNAP25, STX1A, and VAMP2. In the M1 cortex of the rat model, release of amino acid neurotransmitters is increased. Protein levels of glutamate receptor subunit GRIA1 are significantly increased in PRRT2 mutant rats, while GABA receptor subunits GABRA1 are significantly reduced. Both frequency and amplitude of mEPSC are significantly increased, while amplitude of mIPSC is decreased and the ratio of mEPSC/mIPSC is significantly increased. The balance between excitatory and inhibitory neuronal activity is disrupted, which could lead to abnormal neuronal hyperexcitability. These results provide new insights into the function of PRRT2 in synaptic transmission and movement control, as well as the pathogenic mechanism underlying PKC.