title: Overexpression and Nucleolar Localization of γ-Tubulin Small Complex Proteins GCP2 and GCP3 in Glioblastoma.
abstract: The expression, cellular distribution, and subcellular sorting of the microtubule (MT)-nucleating γ-tubulin small complex (γTuSC) proteins, GCP2 and GCP3, were studied in human glioblastoma cell lines and in clinical tissue samples representing all histologic grades of adult diffuse astrocytic gliomas (n = 54). Quantitative real-time polymerase chain reaction revealed a significant increase in the expression of GCP2 and GCP3 transcripts in glioblastoma cells versus normal human astrocytes; these were associated with higher amounts of both γTuSC proteins. GCP2 and GCP3 were concentrated in the centrosomes in interphase glioblastoma cells, but punctate and diffuse localizations were also detected in the cytosol and nuclei/nucleoli. Nucleolar localization was fixation dependent. GCP2 and GCP3 formed complexes with γ-tubulin in the nucleoli as confirmed by reciprocal immunoprecipitation experiments and immunoelectron microscopy. GCP2 and GCP3 depletion caused accumulation of cells in G2/M and mitotic delay but did not affect nucleolar integrity. Overexpression of GCP2 antagonized the inhibitory effect of the CDK5 regulatory subunit-associated tumor suppressor protein 3 (C53) on DNA damage G2/M checkpoint activity. Tumor cell GCP2 and GCP3 immunoreactivity was significantly increased over that in normal brains in glioblastoma samples; it was also associated with microvascular proliferation. These findings suggest that γTuSC protein dysregulation in glioblastomas may be linked to altered transcriptional checkpoint activity or interaction with signaling pathways associated with a malignant phenotype.
authors.affiliation: From the Departments of Biology of Cytoskeleton (ED, VS, TS, VS, PD) and Biology of the Nucleus (MS, PH), Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic; Department of Pediatrics (LD, ET, AL, CDK), Drexel University College of Medicine, Section of Pediatric Neurology and Neurooncology Program (AL, CDK), St. Christopher's Hospital for Children, and Department of Pathology and Laboratory Medicine (NFM, CDK) Drexel University College of Medicine, Philadelphia, Pennsylvania; Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania (VC, AG); Department of Clinical Cytology, Sismanoglion General Hospital, Athens, Greece (NFM); Department of Pathology, KAT General Hospital, Athens, Greece (EM); Department of Pathology, Faculty Hospital Brno, Brno, Czech Republic (LK); and Gades Institute, Department of Pathology, University of Bergen, Haukeland Hospital, Bergen, Norway (SM).
authors.forename: Eduarda
authors.initials: E
authors.lastname: Dráberová
authors.forename: Luca
authors.initials: L
authors.lastname: D'Agostino
authors.forename: Valentina
authors.initials: V
authors.lastname: Caracciolo
authors.forename: Vladimíra
authors.initials: V
authors.lastname: Sládková
authors.forename: Tetyana
authors.initials: T
authors.lastname: Sulimenko
authors.forename: Vadym
authors.initials: V
authors.lastname: Sulimenko
authors.forename: Margaryta
authors.initials: M
authors.lastname: Sobol
authors.forename: Nicoletta F
authors.initials: NF
authors.lastname: Maounis
authors.forename: Elias
authors.initials: E
authors.lastname: Tzelepis
authors.forename: Eleni
authors.initials: E
authors.lastname: Mahera
authors.forename: Leoš
authors.initials: L
authors.lastname: Křen
authors.forename: Agustin
authors.initials: A
authors.lastname: Legido
authors.forename: Antonio
authors.initials: A
authors.lastname: Giordano
authors.forename: Sverre
authors.initials: S
authors.lastname: Mörk
authors.forename: Pavel
authors.initials: P
authors.lastname: Hozák
authors.forename: Pavel
authors.initials: P
authors.lastname: Dráber
authors.forename: Christos D
authors.initials: CD
authors.lastname: Katsetos
mesh_terms: D000818:Animals; D001001:Anura; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism*; D002645:Chickens; D004249:DNA Damage / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D021381:Protein Transport; D014404:Tubulin / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D055815:Young Adult; D015027:Zebrafish
chemical_list: D008869:Microtubule-Associated Proteins; C112305:TUBGCP2 protein, human; C112306:TUBGCP3 protein, human; D014404:Tubulin; D016159:Tumor Suppressor Protein p53