14-3-3 binding to LRRK2 is disrupted by multiple Parkinson's disease associated mutations and regulates cytoplasmic localisation
Résumé
The Leucine-Rich Repeat Protein Kinase 2 (LRRK2) is mutated in a significant number of Parkinson's disease patients, but still little is understood about how it is regulated or functions. Here we demonstrate that 14-3-3 isoforms interact with LRRK2. Consistent with this, endogenous LRRK2 isolated from Swiss 3T3 cells or various mouse tissues is associated with endogenous 14-3-3 isoforms. We also establish that 14-3-3 binding is mediated by phosphorylation of LRRK2 at two conserved residues (Ser910 and Ser935) located before the leucine-rich repeat domain. Our data suggests that mutation of Ser910 and/or Ser935 to disrupt 14-3-3 binding does not affect intrinsic protein kinase activity but induces LRRK2 to accumulate within discrete cytoplasmic pools perhaps resembling inclusion bodies. To investigate links between 14-3-3 binding and Parkinson's disease, we studied how 41 reported mutations of LRRK2 affected 14-3-3 binding and cellular localisation. Strikingly, we find that five of the six most common pathogenic mutations (R1441C, R1441G, R1441H, Y1699C, I2020T) display markedly reduced phosphorylation of Ser910/Ser935 thereby disrupting interaction with 14-3-3. We also demonstrate that Ser910/Ser935 phosphorylation and 14-3-3 binding to endogenous LRRK2 is significantly reduced in tissues of homozygous LRRK2[R1441C] knockin mice. Consistent with 14-3-3 regulating localisation, all of the common pathogenic mutations displaying reduced 14-3-3-binding, accumulated within inclusion bodies. We also found that three of the 41 LRRK2 mutations analysed displayed elevated protein kinase activity (R1728H ~2-fold, G2019S ~3-fold and T2031S ~4-fold). These data provide the first evidence suggesting that 14-3-3 regulates LRRK2 and that disrupting interaction of LRRK2 with 14-3-3 may be linked to Parkinson's disease.
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