Alsin is partially associated with centrosome in human cells.
Mutations in the ALS2 gene has recently been linked to cases of juvenile amyotrophic lateral sclerosis, juvenile primary lateral sclerosis and ascending hereditary spastic paralysis. All reported mutations predict the production of truncated forms of Alsin suggesting a loss of function mechanism for these motor neuron disorders. Here we used the tetracycline-regulated expression system to overexpress the full-length and truncated forms of Alsin in different cell lines. Alsin overexpression caused severe phenotypic changes in monkey COS-7 cells including the enlargement and accumulation of early endosomes, impairment of mitochondria trafficking and fragmentation of the Golgi apparatus. Our results further demonstrate the requirement of the Alsin VPS9 domain for occurrence of the vacuolation process and the role of Alsin as a guanine nucleotide exchange factor for Rab5. Transfected human SW13 cells exhibited an unexpected centrosomal localization for Alsin that was linked to the presence of the c-terminal part of the protein. Immunofluorescence staining revealed a colocalization of Alsin with the centrosomal markers gamma-tubulin and A kinase anchoring protein (AKAP-450). Similar results were obtained with human LA-N-2 and SK-N-SH neuronal cells. Moreover endogenous Alsin was detected in a centrosome preparation purified from human cortical brain. Considering the crucial role of centrosome in the production of microtubules required for intracellular transport, these findings are of potential relevance for unravelling the disease mechanisms linked to Alsin mutations.
Millecamps
Stéphanie
S
Research Centre of CHUQ, Department of Anatomy and Physiology, Laval University, 2705 Boulevard Laurier, Quebec, QC, Canada G1V 4G2.
Gentil
Benoît J
BJ
Gros-Louis
François
F
Rouleau
Guy
G
Julien
Jean-Pierre
JP
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002460:Cell Line; D018385:Centrosome / Q000648:ultrastructure*; D002522:Chlorocebus aethiops; D017931:DNA Primers; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D016472:Motor Neuron Disease / Q000235:genetics; D009154:Mutation; D016133:Polymerase Chain Reaction; D014162:Transfection; D014404:Tubulin / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
C438187:ALS2 protein, human; D017931:DNA Primers; D020662:Guanine Nucleotide Exchange Factors; D014404:Tubulin; D014746:Vimentin; D006160:Guanosine Triphosphate