Evidence for a Role of CLIP-170 in the Establishment of Metaphase Chromosome Alignment

• Published in: The Journal of cell biology Vol. 141; no. 4; pp. 849 - 862
• Main Authors: Dujardin, Denis, Wacker, U. Irene, Moreau, Anne, Schroer, Trina A., Rickard, Janet E., De Mey, Jan R.
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 18.05.1998; The Rockefeller University Press
• Subjects: Animals; Antibodies; Cells; Cellular biology; Chromosomes; Chromosomes - physiology; Chromosomes, Human - physiology; COS Cells; COUP Transcription Factors; Deoxyribonucleic acid; DNA; DNA-Binding Proteins - analysis; Dynactin Complex; Dyneins - analysis; Endocytosis; HeLa Cells; Humans; Kinetochores; Metaphase; Microtubule-Associated Proteins - analysis; Microtubule-Associated Proteins - biosynthesis; Microtubule-Associated Proteins - physiology; Microtubules; Mitosis; Mitotic spindle apparatus; Neoplasm Proteins; Organelles; Phenotype; Receptors, Steroid; Recombinant Proteins - biosynthesis; Transcription Factors - analysis; Transfection; Tumor Cells, Cultured
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.141.4.849

CLIPs (cytoplasmic linker proteins) are a class of proteins believed to mediate the initial, static interaction of organelles with microtubules. CLIP-170, the CLIP best characterized to date, is required for in vitro binding of endocytic transport vesicles to microtubules. We report here that CLIP-170 transiently associates with prometaphase chromosome kinetochores and codistributes with dynein and dynactin at kinetochores, but not polar regions, during mitosis. Like dynein and dynactin, a fraction of the total CLIP-170 pool can be detected on kinetochores of unattached chromosomes but not on those that have become aligned at the metaphase plate. The COOH-terminal domain of CLIP-170, when transiently overexpressed, localizes to kinetochores and causes endogenous full-length CLIP-170 to be lost from the kinetochores, resulting in a delay in prometaphase. Overexpression of the dynactin subunit, dynamitin, strongly reduces the amount of CLIP-170 at kinetochores suggesting that CLIP-170 targeting may involve the dynein/dynactin complex. Thus, CLIP-170 may be a linker for cargo in mitosis as well as interphase. However, dynein and dynactin staining at kinetochores are unaffected by this treatment and further overexpression studies indicate that neither CLIP-170 nor dynein and dynactin are required for the formation of kinetochore fibers. Nevertheless, these results strongly suggest that CLIP-170 contributes in some way to kinetochore function in vivo.