title: Centrosomal nucleolin is required for microtubule network organization.
abstract: Nucleolin is a pleiotropic protein involved in a variety of cellular processes. Although multipolar spindle formation has been observed after nucleolin depletion, the roles of nucleolin in centrosome regulation and functions have not been addressed. Here we report using immunofluorescence and biochemically purified centrosomes that nucleolin co-localized only with one of the centrioles during interphase which was further identified as the mature centriole. Upon nucleolin depletion, cells exhibited an amplification of immature centriole markers surrounded by irregular pericentrin staining; these structures were exempt from maturation markers and unable to nucleate microtubules. Furthermore, the microtubule network was disorganized in these cells, exhibiting frequent non-centrosomal microtubules. At the mature centriole a reduced kinetics in the centrosomal microtubule nucleation phase was observed in live silenced cells, as well as a perturbation of microtubule anchoring. Immunoprecipitation experiments showed that nucleolin belongs to protein complexes containing 2 key centrosomal proteins, γ-tubulin and ninein, involved in microtubule nucleation and anchoring steps. Altogether, our study uncovered a new role for nucleolin in restricting microtubule nucleation and anchoring at centrosomes in interphase cells.
authors.affiliation: a Université de Lyon; Ecole Normale Supérieure de Lyon; CNRS USR 3010; Laboratoire Joliot-Curie ; Lyon , France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Gaume
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Tassin
authors.forename: Iva
authors.initials: I
authors.lastname: Ugrinova
authors.forename: Fabien
authors.initials: F
authors.lastname: Mongelard
authors.forename: Karine
authors.initials: K
authors.lastname: Monier
authors.forename: Philippe
authors.initials: P
authors.lastname: Bouvet
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002502:Centrioles / Q000378:metabolism; D018385:Centrosome / Q000378:metabolism*; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D008870:Microtubules / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D058105:Polymerization; D016601:RNA-Binding Proteins / Q000378:metabolism*; D000097796:Nucleolin
chemical_list: D015415:Biomarkers; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D000097796:Nucleolin
keywords: centrosome; interphase; mature centriole; microtubules; nucleolin