Allosteric Inhibition of Parkinson’s-Linked LRRK2 by Constrained Peptides

Leucine-Rich Repeat
Kinase 2 (LRRK2) is a large, multidomain protein
with dual kinase and GTPase function that is commonly mutated in both
familial and idiopathic Parkinson’s Disease (PD). While dimerization
of LRRK2 is commonly detected in PD models, it remains unclear whether
inhibition of dimerization can regulate catalytic activity and pathogenesis.
Here, we show constrained peptides that are cell-penetrant, bind LRRK2,
and inhibit LRRK2 activation by downregulating dimerization. We further
show that inhibited dimerization decreases kinase activity and inhibits
ROS production and PD-linked apoptosis in primary cortical neurons.
While many ATP-competitive LRRK2 inhibitors induce toxicity and mislocalization
of the protein in cells, these constrained peptides were found to
not affect LRRK2 localization. The ability of these peptides to inhibit
pathogenic LRRK2 kinase activity suggests that disruption of dimerization
may serve as a new allosteric strategy to downregulate PD-related
signaling pathways.