Protein synthesis is suppressed in sporadic and familial Parkinson's Disease by LRRK2

Gain of function LRRK2-G2019S is the most common mutation associated with both familial and sporadic Parkinson9s disease. It is expected therefore that understanding the cellular function of LRRK2 will provide much needed insight on the pathological mechanism of sporadic Parkinson9s, which is the most common form. Here we show that constitutive LRRK2 activity represses nascent protein synthesis in rodent neurons. Specifically, enzymatic inhibition of LRRK2, gene silencing or gene knockout of Lrrk2 increase translation. In the rotenone model of Parkinson9s, LRRK2 activity increases, leading to repression of translation and dopaminergic neuron atrophy both of which are prevented by LRRK2 inhibition. This is accompanied by altered phosphorylation of eIF2α-S52(↑), eIF2s2-S2(↓) and eEF2-T57(↑) in striatum/substantia nigra in a direction that signifies inhibition of protein synthesis. Significantly, LRRK2 is activated and translation is 40% reduced in Parkinson9s patient fibroblasts (G2019S and sporadic) and LRRK2 inhibition restores normal translation. In contrast, translation is unchanged in cells from multiple system atrophy patients, implying disease specificity. These findings suggest that LRRK2-dependent repression of translation may be a proximal function of LRRK2 in Parkinson9s pathology.