title: Identification and characterization of novel NuMA isoforms.
abstract: The large nuclear mitotic apparatus (NuMA) has been investigated for over 30years with functions related to the formation and maintenance of mitotic spindle poles during mitosis. However, the existence and functions of NuMA isoforms generated by alternative splicing remains unclear. In the present work, we show that at least seven NuMA isoforms (categorized into long, middle and short groups) generated by alternative splicing from a common NuMA mRNA precursor were discovered in HeLa cells and these isoforms differ mainly at the carboxyl terminus and the coiled-coil domains. Two "hotspot" exons with molecular mass of 3366-nt and 42-nt tend to be spliced during alternative splicing in long and middle groups. Furthermore, full-length coding sequences of long and middle NuMA obtained by using fusion PCR were constructed into GFP-tagged vector to illustrate their cellular localization. Long NuMA mainly localized in the nucleus with absence from nucleoli during interphase and translocated to the spindle poles in mitosis. Middle NuMA displayed the similar cell cycle-dependent distribution pattern as long NuMA. However, expression of NuMA short isoforms revealed a distinct subcellular localization. Short NuMA were present in the cytosol during the whole cycle, without colocalization with mitotic apparatus. These results have allowed us tentatively to explore a new research direction for NuMA's various functions.
authors.affiliation: Key Laboratory for Cell Proliferation and Regulation of the Ministry of Education, Beijing Normal University, Beijing, PR China. Electronic address: petersdu2112@hotmail.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Clinical Laboratory Diagnosis, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China; Core Laboratory for Clinical Medical Research, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Key Laboratory for Cell Proliferation and Regulation of the Ministry of Education, Beijing Normal University, Beijing, PR China.
authors.forename: Dacheng
authors.initials: D
authors.lastname: He
authors.affiliation: Beijing DnaLead Science and Technology Co., LTD, Beijing, PR China. Electronic address: guantlv@126.com.
authors.forename: Guanting
authors.initials: G
authors.lastname: Lu
mesh_terms: D017398:Alternative Splicing; D034961:Antigens, Nuclear / Q000032:analysis* / Q000235:genetics*; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002460:Cell Line; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D009369:Neoplasms / Q000235:genetics; D034521:Nuclear Matrix-Associated Proteins / Q000032:analysis* / Q000235:genetics*; D000072417:Protein Domains; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger
keywords: Alternative splicing; Cell cycle; Cellular localization; Coiled-coil domain; Fusion PCR