|Page Contents: Abstract|
Song, Lin, Rijal, Ramesh, Karow, Malte, Stumpf, Maria, Hahn, Oliver, Park, Laura, Insall, Robert, Schroder, Rolf, Hofmann, Andreas, Clemen, CS Christoph S, Eichinger, Ludwig, (2018)
' Expression of N471D strumpellin leads to defects in the endolysosomal system. '
Dis Model Mech
|Abstract:Hereditary Spastic Paraplegias (HSP) are genetically diverse and clinically characterized by lower limb weakness and spasticity. The N471D and several other point mutations of human strumpellin (Str), a member of the WASH (Wiskott-Aldrich Syndrome Protein and SCAR Homologue) complex, have been shown to cause HSP type 8 (SPG8). To investigate the molecular functions of wild type and N417D Str, we generated Dictyostelium Str- cells and ectopically expressed Strwt-GFP or StrN471D-GFP in Str- and wt cells. Overexpression of both proteins apparently caused a defect in cell division as we observed a clear increase in multinucleate cells. Real time PCR analyses revealed no transcriptional changes in WASH complex subunits in Str- cells, but Western blots showed a two-fold decrease in the SWIP subunit. GFP-trap experiments in conjunction with mass-spectrometric analysis revealed many previously known as well as new Str interacting proteins and also proteins that did no longer bind to StrN471D On the cellular level, Str- cells displayed defects in cell growth, phagocytosis, macro-pinocytosis, exocytosis and lysosomal function. Expression of Strwt-GFP in Str- cells rescued all observed defects. In contrast, expression of StrN471D-GFP could not rescue lysosome morphology and exocytosis of indigestible material. Our results underscore a key role for the WASH complex and its core subunit Str in the endo-lysosomal system and highlight the fundamental importance of the Str N471 residue for maintaining lysosome morphology and dynamics. Our data indicate that the SPG8-causing N471D mutation leads to a partial loss of Strumpellin function in the endo-lysosomal system.|
|Status:||aheadofprint||Type:||Journal article||Source:||PUBMED||PubMed ID:||30061306|