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Proliferation marker pKi‐67 occurs in different isoforms with various cellular effects
Author(s) -
Schmidt Mirko H.H.,
Broll Rainer,
Bruch HansPeter,
Finniss Susan,
Bögler Oliver,
Duchrow Michael
Publication year - 2004
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.20016
Subject(s) - gene isoform , alternative splicing , biology , exon , mitosis , cell cycle , rna splicing , microbiology and biotechnology , cell growth , peripheral blood mononuclear cell , splice , gene , genetics , rna , in vitro
Abstract The Ki‐67 antigen, pKi‐67, is a commonly used proliferation marker in research and pathology. It has been recognized that the protein exists in two different splice variants that differ in one exon. In the current work, we present three new splice variants of human pKi‐67 consisting of two naturally occurring isoforms and one atypical version. Additionally, data is presented indicating that alternative splicing of the pKi‐67 N‐terminus is common in tumor cell lines. Analyzing 93 tissues mainly consisting of brain tumor specimens, we found evidence that long and short isoform can be expressed independently of each other. Induction of mitosis in human peripheral blood mononuclear cells revealed that short pKi‐67 appears earlier in the cell cycle than the long isoform and reaches its expression maximum when transcription of the latter sets in. Finally, transfection of mammalian culture cells with exon 7 (specific for the long pKi‐67 isoform and not present in the short isoform) in a tetracycline regulated expression system decreased the rate of cell proliferation without affecting the cell cycle. In summary, we present evidence that the pKi‐67 N‐terminus is differentially spliced resulting in at least five different isoforms with different functions. © 2004 Wiley‐Liss, Inc.