Nucleolar association of pEg7 and XCAP-E, two members of Xenopus laevis condensin complex in interphase cells

• Published in: Journal of cell science Vol. 116; no. Pt 9; pp. 1667 - 1678
• Main Authors: Uzbekov, Rustem, Timirbulatova, Elmira, Watrin, Erwan, Cubizolles, Fabien, Ogereau, David, Gulak, Pavel, Legagneux, Vincent, Polyakov, Vladimir Ju, Le Guellec, Katherine, Kireev, Igor
• Format: Journal Article
• Language: English
• Published: England Company of Biologists 01.05.2003
• Subjects: Adenosine Triphosphatases; Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - metabolism; Animals; Biochemistry, Molecular Biology; Carrier Proteins; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell Cycle; Cell Cycle - physiology; Cell Cycle Proteins; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - metabolism; Cell Line; Cell Nucleolus; Cell Nucleolus - metabolism; Chromosomes; Chromosomes - metabolism; DNA-Binding Proteins; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; Egg Proteins; Egg Proteins - chemistry; Egg Proteins - metabolism; Genomics; Interphase; Interphase - physiology; Life Sciences; Macromolecular Substances; Microscopy, Immunoelectron; Multiprotein Complexes; Nuclear Proteins; Nuclear Proteins - chemistry; Nuclear Proteins - metabolism; RNA, Ribosomal; RNA, Ribosomal - genetics; RNA, Ribosomal - metabolism; Transcription, Genetic; Xenopus laevis; Xenopus Proteins
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.00311

Cell cycle dynamics and localization of condensins--multiprotein complexes involved in late stages of mitotic chromosome condensation--were studied in Xenopus laevis XL2 cell line. Western blot analysis of synchronized cells showed that the ratio of levels of both pEg7 and XCAP-E to beta-tubulin levels remains almost constant from G1 to M phase. pEg7 and XCAP-E were localized to the mitotic chromosomes and were detected in interphase nuclei. Immunostaining for condensins and nucleolar proteins UBF, fibrillarin and B23 revealed that both XCAP-E and pEg7 are localized in the granular component of the nucleolus. Nucleolar labeling of both proteins is preserved in segregated nucleoli after 6 hours of incubation with actinomycin D (5 mg/ml), but the size of the labeled zone was significantly smaller. The data suggest a novel interphase function of condensin subunits in spatial organization of the nucleolus and/or ribosome biogenesis.