Cytoplasmic Pink1 activity protects neurons from dopaminergic neurotoxin MPTP

*Ottawa Health Research Institute, Neuroscience Group, University of Ottawa, Ottawa, ON, Canada K1H 8M5;
^†Laboratory of Neurogenetics, National Institute on Aging, 35 Convent Drive, Bethesda, MD 20892-3707;
^§Center for Neurologic Diseases, Harvard Medical School, Boston, MA 02115; and
^‡Centre for Research in Neurodegenerative Diseases, University of Toronto, 6 Queen's Park Crescent West, Toronto, ON, Canada M5S 3H2

Edited by Tak Wah Mak, University of Toronto, Toronto, ON, Canada, and approved December 12, 2007 (received for review June 7, 2007)

Abstract

PTEN-induced putative kinase 1 (Pink1) is a recently identified gene linked to a recessive form of familial Parkinson's disease (PD). The kinase contains a mitochondrial localization sequence and is reported to reside, at least in part, in mitochondria. However, neither the manner by which the loss of Pink1 contributes to dopamine neuron loss nor its impact on mitochondrial function and relevance to death is clear. Here, we report that depletion of Pink1 by RNAi increased neuronal toxicity induced by MPP⁺. Moreover, wild-type Pink1, but not the G309D mutant linked to familial PD or an engineered kinase-dead mutant K219M, protects neurons against MPTP both in vitro and in vivo. Intriguingly, a mutant that contains a deletion of the putative mitochondrial-targeting motif was targeted to the cytoplasm but still provided protection against 1-methyl-4-phenylpyridine (MPP⁺)/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity. In addition, we also show that endogenous Pink1 is localized to cytosolic as well as mitochondrial fractions. Thus, our findings indicate that Pink1 plays a functional role in the survival of neurons and that cytoplasmic targets, in addition to its other actions in the mitochondria, may be important for this protective effect.

Footnotes

^¶To whom correspondence should be addressed. E-mail: dpark{at}uottawa.ca
Author contributions: A.T. and D.S.P. contributed equally to this work; M.E.H. and D.S.P. designed research; M.E.H., K.J.T., P.F., and M.R.C. performed research; K.J.T., C.D., S.C., T.K., R.S.S., M.R.C., and A.T. contributed new reagents/analytic tools; M.E.H., P.F., and D.S.P. analyzed data; and M.E.H. and D.S.P. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0705363105/DC1.