Nuclear mitotic apparatus protein (NuMA): Spindle association, nuclear targeting and differential subcellular localization of various NuMA isoforms

Tang K. Tang*, Chieh Ju C. Tang, Yu Jane Chao, Cheng-Wen Wu Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

We have recently shown that the nuclear mitotic apparatus protein (NuMA) is composed of at least three isoforms that differ mainly at the carboxy terminus, and are generated by alternative splicing of a common mRNA precursor from a single NuMA gene. Transient expression of human NuMA-l isoform (T33/p230) in Chinese hamster ovary polyoma (CHOP) cells showed that NuMA-1 was present in interphase nuclei and was concentrated at the polar regions of the spindle apparatus in mitotic cells. However, expression of two other isoforms (NuMA-m and -s) revealed a distinct subcellular localization. NuMA-m (U4/p195) and NuMA-s (U6/p194) were present in the interphase cytosol and appeared to be mainly located at the centrosomal region. When cells entered into mitosis, however, NuMA-m and -s moved to the mitotic spindle pole. Analysis of a series of linker scanning-mutants and NuMA/β-galactosidase chimeric proteins showed that residues 1972-2007 of NuMA-1 constitute a novel nuclear localization signal (NLS) and residues 1538-2115 are necessary and sufficient for spindle association. Further analysis of the NLS by site specific mutagenesis indicated that Lys1988 is essential for nuclear targeting, whereas Arg1984 is not. These results have allowed us tentatively to assign specific biological activities to distinct structural domains of the NuMA polypeptide.

Original languageEnglish
Pages (from-to)1389-1402
Number of pages14
JournalJournal of Cell Science
Volume107
Issue number6
StatePublished - 1 Jun 1994

Keywords

  • Centrosome
  • Nuclear localization signal
  • Nuclear protein
  • NuMA
  • Spindle pole

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