L16.    Functional evidence supporting the use of human scalp melanocytes in neurodegeneration research: cytotoxicity of amyloid beta peptides and interactions between amyloid precursor protein and the adaptor protein Fe65.
Nikolaos Papageorgiou, Elizabeth Carpenter, Desmond Tobin; Medical Biosciences, School of Life Sciences, University of Bradford, Bradford, UK.

The neurodegenerative disorder Alzheimer’s disease (AD) is an increasing financial and social burden to ageing populations of the developed world. AD pathology is associated with the extracellular deposition of amyloid beta peptides (Abeta40 and Abeta42), leading to the formation of senile plaques in affected brains. These peptides are cleaved from the amyloid precursor protein (APP) by beta- and gamma-secretases. It has been suggested that cutaneous melanocytes may be a useful proxy for neurones in neurodegeneration research due to their sharing a close embryonic origin and multiple other similarities. In this study we examined the expression of neuron-associated proteins in cultured follicular and epidermal melanocytes and tested these cells in vitro under conditions similar to those found in AD. Human scalp melanocytes were incubated with increasing concentrations (1 microM, 10 microM and 30 microM) of aggregated (confirmed by native 16%-PAGE) Abeta40 peptide. Results showed a significant reduction in melanocyte viability (MTT assay) after 24, 48 and 72 hrs with 10 microM and 30 microM Abeta40, supporting a functional similarity between melanocytes and neurones in the context of AD. As the intracellular domain fragment of amyloid beta precursor protein is thought to activate Fe65-dependent gene expression in AD, we also examined whether this may also occur in melanocytic cells by probing melanoma nuclei for the adaptor protein Fe65 and the last 15 amino acids of the C-terminus of APP (APPCT15). Studies revealed the presence of both proteins in melanoma nuclei, suggesting their potential for interaction with subsequent Fe65-dependent gene transactivation, potentially also possible in cutaneous cells. We are currently examining whether Fe65 and APPCT15 exist as a complex in melanocytes, including hair follicle melanocytes (i.e. can be co-immunoprecipitated), as this would further support the potential use of cutaneous melanocytes as a neuronal proxy in AD and neurodegeneration research.