The Role of the Parkinson's Disease Gene PARK9 in Essential Cellular Pathways and the Manganese Homeostasis Network in Yeast
Gitler AD (2012) The Role of the Parkinson's Disease Gene PARK9 in Essential Cellular Pathways and the
Manganese Homeostasis Network in Yeast. PLoS ONE 7(3): e34178. doi:10.1371/journal.pone.0034178
The Role of the Parkinson's Disease Gene PARK9 in Essential Cellular Pathways and the Manganese Homeostasis Network in Yeast
Alessandra Chesi 0
Austin Kilaru 0
Xiaodong Fang 0
Antony A. Cooper 0
Aaron D. Gitler 0
Philipp J. Kahle, Hertie Institute for Clinical Brain Research and German Center for Neurodegenerative Diseases, Germany
0 1 Department of Genetics, Stanford University School of Medicine, Stanford University, Stanford, California, United States of America, 2 Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America, 3 Garvan Institute of Medical Research, University of New South Wales , Sydney, New South Wales , Australia
YPK9 (Yeast PARK9; also known as YOR291W) is a non-essential yeast gene predicted by sequence to encode a transmembrane P-type transport ATPase. However, its substrate specificity is unknown. Mutations in the human homolog of YPK9, ATP13A2/ PARK9, have been linked to genetic forms of early onset parkinsonism. We previously described a strong genetic interaction between Ypk9 and another Parkinson's disease (PD) protein a-synuclein in multiple model systems, and a role for Ypk9 in manganese detoxification in yeast. In humans, environmental exposure to toxic levels of manganese causes a syndrome similar to PD and is thus an environmental risk factor for the disease. How manganese contributes to neurodegeneration is poorly understood. Here we describe multiple genome-wide screens in yeast aimed at defining the cellular function of Ypk9 and the mechanisms by which it protects cells from manganese toxicity. In physiological conditions, we found that Ypk9 genetically interacts with essential genes involved in cellular trafficking and the cell cycle. Deletion of Ypk9 sensitizes yeast cells to exposure to excess manganese. Using a library of non-essential gene deletions, we screened for additional genes involved in tolerance to excess manganese exposure, discovering several novel pathways involved in manganese homeostasis. We defined the dependence of the deletion strain phenotypes in the presence of manganese on Ypk9, and found that Ypk9 deletion modifies the manganese tolerance of only a subset of strains. These results confirm a role for Ypk9 in manganese homeostasis and illuminates cellular pathways and biological processes in which Ypk9 likely functions.
-
Funding: This work was supported by National Institutes of Health Directors New Innovator Award 1DP2OD004417 awarded to ADG. By a Postdoctoral
Fellowship from the Parkinson Disease Foundation to AC. ADG is a Pew Scholar in the Biomedical Sciences, supported by The Pew Charitable Trusts and a Rita
Allen Foundation Scholar. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Ypk9 (YOR291W) is a non-essential gene in the budding yeast,
Saccahromyces cerevisiae, predicted by sequence to belong to a family
of cationic P-type transport ATPases of unknown substrate
specificity. Recently, mutations in the human homolog of Ypk9,
ATP13A2/PARK9, have been linked to Parkinsons disease (PD)
and PD-like Kufor-Rakeb syndrome [1]. PD is associated with a
spectrum of diverse genetic and environmental susceptibilities [2].
a-Synuclein (a-syn) is the best studied of the genetic factors, with
point mutations in its coding sequence or duplications and
triplications of its entire locus causing early onset autosomal
dominant forms of familial PD [3,4,5]. a-Syn plays a key role in
sporadic PD as well, being the major component of Lewy bodies,
the proteinaceous inclusions characteristic of the disease [6].
Expression of a-syn in multiple model systems including yeast,
worm, fly, and mouse is sufficient to cause neurodegeneration, and
simple experimental model systems have proven to be an
invaluable tool to gain insight into basic cellular mechanisms by
which a-syn might contribute to disease [7,8,9,10].
When expressed in yeast at low levels, a-syn localizes to the
plasma membrane, consistent with its presynaptic localization in
neurons. Increasing the level of expression causes a growth defect
and relocalization of a-syn to cytoplasmic inclusions composed of
clusters of mislocalized transport vesicles from various steps of the
endocytic and exocytic pathways [11,12,13].
We previously identified Ypk9 as a potent modifier of a-syn
toxicity in an unbiased yeast genetic screen [14,15]. Importantly,
the ability of Ypk9 to rescue a-syn toxicity is conserved and
upregulation of the mammalian PARK9 gene is sufficient to
rescue a-syn-induced neurodegeneration in multiple animal
models [14]. However, the mechanis (...truncated)