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Tetraspanin 3: A central endocytic membrane component regulating the expression of ADAM10, presenilin and the amyloid precursor protein
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Despite existing knowledge about the role of the A Disintegrin and Metalloproteinase 10 (ADAM10) as the α-secretase involved in the non-amyloidogenic processing of the amyloid precursor protein (APP) and Notch signalling we have only limited information about its regulation. In this study, we have identified ADAM10 interactors using a split ubiquitin yeast two hybrid approach. Tetraspanin 3 (Tspan3), which is highly expressed in the murine brain and elevated in brains of Alzheimer's disease (AD) patients, was identified and confirmed to bind ADAM10 by co-immunoprecipitation experiments in mammalian cells in complex with APP and the γ-secretase protease presenilin. Tspan3 expression increased the cell surface levels of its interacting partners and was mainly localized in early and late endosomes. In contrast to the previously described ADAM10-binding tetraspanins, Tspan3 did not affect the endoplasmic reticulum to plasma membrane transport of ADAM10. Heterologous Tspan3 expression significantly increased the appearance of carboxy-terminal cleavage products of ADAM10 and APP, whereas N-cadherin ectodomain shedding appeared unaffected. Inhibiting the endocytosis of Tspan3 by mutating a critical cytoplasmic tyrosine-based internalization motif led to increased surface expression of APP and ADAM10. After its downregulation in neuroblastoma cells and in brains of Tspan3-deficient mice, ADAM10 and APP levels appeared unaltered possibly due to a compensatory increase in the expression of Tspans 5 and 7, respectively. In conclusion, our data suggest that Tspan3 acts in concert with other tetraspanins as a stabilizing factor of active ADAM10, APP and the γ-secretase complex at the plasma membrane and within the endocytic pathway.
ADAM10 , Tetraspanin , APP , Presenilin
Seipold, L., Damme, M., Prox, J., Rabe, B., Kasparek, P., SedlaceK, R., Altmeppen, H., Willem, M., Boland, B., GlatzeL, M. and Saftig, P. (2016) ‘Tetraspanin 3: A central endocytic membrane component regulating the expression of ADAM10, presenilin and the amyloid precursor protein’, Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1864(1), pp. 217-230. doi: 10.1016/j.bbamcr.2016.11.003