Objective/Rationale:
Mutations in the ATP13A2 gene lead to the Kufor-Rakeb syndrome, a severe early-onset form of Parkinson’s disease (PD) with dementia. The ATP13A2 protein is targeted to cellular structures known as lysosomes and belongs to the family of P-type ATPases. All known members of this family are transporters, performing energy-dependent translocations of a specific substrate within the cell. For ATP13A2, the substrate remains unknown. We aim to uncover the substrate to find out how its impaired transport causes PD.
Project Description:
We will first specify the distribution within the cell of three known ATP13A2 variants to get insights in which cellular functions these proteins might be involved. Since the membrane-associated parts of ATP13A2 hold the site for substrate transport, we will explore which fragments of ATP13A2 are associated with the membrane. To uncover the substrate, ATP13A2 will be expressed in yeast and purified. The purified ATP13A2 protein will facilitate the substrate screen, which might either be a lipid or an ion such as Mn2+. Once the substrate is known, a biochemical transport assay can be developed to study the activity of ATP13A2 or disease-associated mutants. As an alternative approach, the impact of normal and mutated ATP13A2 on PD-related conditions, such as α-synuclein or Mn2+ overload, will be assessed in mammalian cells via lentiviral overexpression.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
To understand the central role of ATP13A2 in Parkinson’s disease, it is imperative to specify its transported substrate. Once this is known, one can hope to correct the affected transport systems during neurodegeneration by either impacting on the protein activity or on factors affecting the levels of the transported substrate. It will also become possible to test whether certain sporadic genetic mutations in the ATP13A2 gene impact the activity of the protein and may be a risk factor to develop PD.
Anticipated Outcome:
The first and main outcome of the project would be to gain fundamental insight in the cellular role of ATP13A2 under normal and pathological conditions. Finding the transported substrate of ATP13A2 will also remove a crucial bottleneck for understanding the affected cellular activities during neurodegeneration. Our research might therefore open the path to design novel therapeutic approaches for Parkinson’s disease.