The G2385R risk factor for Parkinson's disease enhances CHIP-dependent intracellular degradation of LRRK2.
Autosomal dominant mutations inleucine-rich repeat kinase 2(LRRK2) are associated with Parkinson's disease (PD). Most pathogenicLRRK2mutations result in amino acid substitutions in the central ROC (Ras of complex proteins)-C-terminus of ROC-kinase triple domain and affect enzymatic functions of the protein. However, there are several variants inLRRK2, including the risk factor G2385R, that affect PD pathogenesis by unknown mechanisms. Previously, we have shown that G2385R LRRK2 has decreased kinase activityin vitroand altered affinity to LRRK2 interactors. Specifically, we found an increased binding to the chaperone Hsp90 (heat shock protein 90 kDa) that is known to stabilize LRRK2, suggesting that G2385R may have structural effects on LRRK2. In the present study, we further explored the effects of G2385R on LRRK2 in cells. We found that G2385R LRRK2 has lower steady-state intracellular protein levels compared with wild-type LRRK2 due to increased protein turnover of the mutant protein. Mechanistically, this is a consequence of a higher affinity of G2385R compared with the wild-type protein for two proteins involved in proteasomal degradation, Hsc70 and carboxyl-terminus of Hsc70-interacting protein (CHIP). Overexpression of CHIP decreased intracellular protein levels of both G2385R mutant and wild-type LRRK2, while short interfering RNA CHIP knockdown had the opposite effect. We suggest that the G2385R substitution tilts the equilibrium between refolding and proteasomal degradation toward intracellular degradation. The observation of lower steady-state protein levels may explain why G2385R is a risk factor rather than a penetrant variant for inherited PD.
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A. cookson@mail.nih.gov iakov.rudenko@stonybrookmedicine.edu.
Iakov N
IN
Rudenko
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Alice
A
Kaganovich
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Rebekah G
RG
Langston
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Aleksandra
A
Beilina
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Kelechi
K
Ndukwe
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Ravindran
R
Kumaran
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Allissa A
AA
Dillman
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A.
Ruth
R
Chia
Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, NIH, 35 Convent Drive, Room 1A-116, Bethesda, MD 20892-3707, U.S.A. cookson@mail.nih.gov iakov.rudenko@stonybrookmedicine.edu.
Mark R
MR
Cookson
D055785:Gene Knockdown Techniques; D020022:Genetic Predisposition to Disease; D057809:HEK293 Cells; D006801:Humans; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 / Q000235:genetics*; D009154:Mutation; D010300:Parkinson Disease / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D059748:Proteolysis; D012307:Risk Factors; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
C467728:STUB1 protein, human; D044767:Ubiquitin-Protein Ligases; C495280:LRRK2 protein, human; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D046988:Proteasome Endopeptidase Complex
CHIP; G-proteins; Parkinson's disease; proteasome; protein stability