Nuf2 and Hec1 Are Required for Retention of the Checkpoint Proteins Mad1 and Mad2 to Kinetochores
| Autor: | Julie C. Canman, Edward D. Salmon, Bonnie Howell, Jennifer M. Hickey, Guowei Fang, Jennifer G. DeLuca |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Mad2
Mad1 Fluorescent Antibody Technique Gene Expression Cell Cycle Proteins Spindle Apparatus Biology General Biochemistry Genetics and Molecular Biology 03 medical and health sciences 0302 clinical medicine Mad2 Proteins Humans Prometaphase Kinetochores Mitosis Metaphase 030304 developmental biology 0303 health sciences Agricultural and Biological Sciences(all) Biochemistry Genetics and Molecular Biology(all) Kinetochore Calcium-Binding Proteins Nuclear Proteins Phosphoproteins Cell biology Repressor Proteins Cytoskeletal Proteins Spindle checkpoint RNA Interference General Agricultural and Biological Sciences 030217 neurology & neurosurgery HeLa Cells |
| Zdroj: | Current Biology. 13:2103-2109 |
| ISSN: | 0960-9822 |
| Popis: | Members of the Ndc80/Nuf2 complex have been shown in several systems to be important in formation of stable kinetochore-microtubule attachments and chromosome alignment in mitosis 1, 2, 3, 4, 5, 6, 7, 8 and 9. In HeLa cells, we have shown that depletion of Nuf2 by RNA interference (RNAi) results in a strong prometaphase block with an active spindle checkpoint, which correlates with low but detectable Mad2 at kinetochores that have no or few stable kinetochore microtubules [5]. Another RNAi study in HeLa cells reported that Hec1 (the human Ndc80 homolog) is required for Mad1 and Mad2 binding to kinetochores and that kinetochore bound Mad2 does not play a role in generating and maintaining the spindle assembly checkpoint [6]. Here, we show that depletion of either Nuf2 or Hec1 by RNAi in HeLa cells results in reduction of both proteins at kinetochores and in the cytoplasm. Mad1 and Mad2 concentrate at kinetochores in late prophase/early prometaphase but become depleted by 5-fold or more over the course of the prometaphase block, which is Mad2 dependent. The reduction of Mad1 and Mad2 is reversible upon spindle depolymerization. Our observations support a model in which Nuf2 and Hec1 function to prevent microtubule-dependent stripping of Mad1 and Mad2 from kinetochores that have not yet formed stable kinetochore-microtubule attachments. |
| Databáze: | OpenAIRE |
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