G2019S-LRRK2 Expression Augments α-Synuclein Sequestration into Inclusions in Neurons

J Neurosci. 2016 Jul 13;36(28):7415-27. doi: 10.1523/JNEUROSCI.3642-15.2016.


Pathologic inclusions define α-synucleinopathies that include Parkinson's disease (PD). The most common genetic cause of PD is the G2019S LRRK2 mutation that upregulates LRRK2 kinase activity. However, the interaction between α-synuclein, LRRK2, and the formation of α-synuclein inclusions remains unclear. Here, we show that G2019S-LRRK2 expression, in both cultured neurons and dopaminergic neurons in the rat substantia nigra pars compact, increases the recruitment of endogenous α-synuclein into inclusions in response to α-synuclein fibril exposure. This results from the expression of mutant G2019S-LRRK2, as overexpression of WT-LRRK2 not only does not increase formation of inclusions but reduces their abundance. In addition, treatment of primary mouse neurons with LRRK2 kinase inhibitors, PF-06447475 and MLi-2, blocks G2019S-LRRK2 effects, suggesting that the G2019S-LRRK2 potentiation of inclusion formation depends on its kinase activity. Overexpression of G2019S-LRRK2 slightly increases, whereas WT-LRRK2 decreases, total levels of α-synuclein. Knockdown of total α-synuclein with potent antisense oligonucleotides substantially reduces inclusion formation in G2019S-LRRK2-expressing neurons, suggesting that LRRK2 influences α-synuclein inclusion formation by altering α-synuclein levels. These findings support the hypothesis that G2019S-LRRK2 may increase the progression of pathological α-synuclein inclusions after the initial formation of α-synuclein pathology by increasing a pool of α-synuclein that is more susceptible to forming inclusions.

Significance statement: α-Synuclein inclusions are found in the brains of patients with many different neurodegenerative diseases. Point mutation, duplication, or triplication of the α-synuclein gene can all cause Parkinson's disease (PD). The G2019S mutation in LRRK2 is the most common known genetic cause of PD. The interaction between G2019S-LRRK2 and α-synuclein may uncover new mechanisms and targets for neuroprotection. Here, we show that expression of G2019S-LRRK2 increases α-synuclein mobility and enhances aggregation of α-synuclein in primary cultured neurons and in dopaminergic neurons of the substantia nigra pars compacta, a susceptible brain region in PD. Potent LRRK2 kinase inhibitors, which are being developed for clinical use, block the increased α-synuclein aggregation in G2019S-LRRK2-expressing neurons. These results demonstrate that α-synuclein inclusion formation in neurons can be blocked and that novel therapeutic compounds targeting this process by inhibiting LRRK2 kinase activity may slow progression of PD-associated pathology.

Keywords: LRRK2; Lewy body; Lewy neurite; Parkinson's; synuclein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Gene Expression Regulation / genetics
  • Humans
  • Inclusion Bodies / pathology*
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 / genetics*
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mutation / genetics*
  • Neurons / metabolism*
  • Oligoribonucleotides, Antisense / pharmacology
  • Photobleaching
  • Rats
  • Synucleins / metabolism
  • Transcytosis / genetics
  • Transcytosis / physiology*
  • Tubulin / metabolism
  • Voltage-Dependent Anion Channels / genetics
  • Voltage-Dependent Anion Channels / metabolism
  • alpha-Synuclein / metabolism*


  • Oligoribonucleotides, Antisense
  • Synucleins
  • Tubulin
  • Voltage-Dependent Anion Channels
  • alpha-Synuclein
  • beta3 tubulin, mouse
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
  • Lrrk2 protein, mouse