Testing molecular models of SPG11 function in the fruitfly Drosophila

Dr Cahir O'Kane

Department of Genetics,
University of Cambridge,
Downing Street,
Cambridge CB2 3EH,
United Kingdom

Email: c.okane@gen.cam.ac.uk


SPG11 loss-of-function mutations are the most common cause of autosomal recessive HSP with thin-corpus callosum (ARHSP-TCC). Since most SPG11 phenotypes are loss-of-function, elucidating the cellular function of SPG11 is essential to understand its role, and how its loss can lead to degeneration. SPG11 was recently implicated in the endolysosomal and autophagy pathways; loss-of-func­tion mutations abolish autophagic lysosome reformation (ALR), causing enlarged autolysoso­mes and fewer free lysosomes. Since autophagy has a number of potentially druggable control points (14), understanding SPG11 action in autophagic trafficking may have concrete outcomes for therapeutic strategies.   Identification of binding partners can help reveal how SPG11 protein acts. Recently Drosophila SPG11 was found to bind the trafficking protein Rab7, and we have found abnormalities in Rab7 localization in Drosophila spg11 mutants, suggesting that SPG11 might function at least partly via effects on Rab7. Through sequence comparisons we have also detected unexpected conservation of part of the SPG11 protein to another family of membrane trafficking proteins. This homology makes certain predictions about the binding partners that we might expect to find for this domain. The purpose of our TWS project is to test these predictions using yeast two-hybrid assays, as well as unbiased identification of binding partners by mass spectrometry. Assessment of these binding partners will allow us to develop further concrete models of how SPG11 might affect endolysosomal or autophagic trafficking

The o'Kane Team

Cahir O'Kane; Lu ("Lulu") Zhao; Belgin Yalçin; Megan Oliva; Juanjo Perez Moreno; Alex Patto