Affiliations: Dipartimento di Medicina, Chirurgia e Odontoiatria, Sezione di Genetica Medica, Università di Milano, Milan, Italy | Dipartimento di Scienze Neurologiche, Università di Milano, Milan, Italy
Note: [] Corresponding author: Lidia Larizza, Dipartimento di Medicina, Chirurgia e Odontoiatria, Sezione di Genetica Medica, Università di Milano, Polo San Paolo, via di Rudinì, 8, 20142 Milan, Italy. Tel.: +39 02 50323206; Fax: +39 02 50323026; E-mail: lidia.larizza@unimi.it.
Abstract: Background: We have previously shown that the sustained expression of MARK4L transcripts in glioma and neural progenitors (NHNPs) declines after exposure to antisense MARK4L oligonucleotides in glioblastoma cell lines. Array-CGH confirmed the genomic duplication of MARK4L identified by FISH in a glioblastoma cell line. This background together with literature data on the exogenous association of MARK4 with interphase centrosome prompted us to investigate the sub-cellular localization of the endogenous MARK4L protein aiming at achieving insights on its possible role in the pathomechanisms of glioma. Methods: Immunodetection was carried out to validate the specificity of MARK4L antibody in gliomas and NHNPs. Mass spectrometry was applied for MARK4L protein identification in a representative glioblastoma cell line. Combined biochemical fractionation and immunodetection analyses were performed to confirm the sub-cellular localization of MARK4L achieved by immunofluorescence in glioma cell lines. Results: By assigning MARK4L protein within the band immunoprecipitated by the specific antibody we validated our anti-MARK4L antibody. We demonstrated that the endogenous MARK4L: (i) colocalizes with centrosomes at all mitotic stages and resides in centrosome-enriched fractions; (ii) associates with the nucleolus and the midbody and respective fractions, and (iii) co-stains the aberrant centrosome configurations observed in glioma cell lines. Conclusion: The overall data merge on the multiplex entry of MARK4L into the cell cycle and link it to the aberrant centrosomes in glioma cell lines suggesting a possible role of this kinase in the abnormal mitotic processes of human glioma.
