Eight full‐length abelson related gene (Arg) isoforms are constitutively expressed in caki‐1 cell line and cell distribution of two isoforms has been analyzed after transfection

Abstract

The human Arg (Abl2) nonreceptor tyrosine kinase has a role in cytoskeletal rearrangements by its C-terminal F-actin- and microtubule-binding sequences. We have previously identified Arg transcripts with different 5'- and 3'-ends, named respectively long and short 1A and 1B (1AL, 1AS, 1BL, 1BS) and long and short C-termini (CTL and CTS), that have different expression patterns in various cell types. The combination of the different ends permits to predict eight putative full-length Arg transcripts and corresponding proteins. By Reverse Transcription-Long PCR we show here that all eight full-length transcripts are endogenously expressed in Caki-1 cells and the two bands, approximately 10 kDa different, shown by 1-D Western blots of Hek293T and Caki-1 lysates correspond to the full-length Arg protein isoforms with different C-termini. 2-D Western blot analysis evidenced different high molecular weight and slight acidic specific spots in Hek293T and Caki-1 lysates. The cellular localization of two Arg isoforms (1BLCTL and 1BLCTS) transfected in Caki-1 and Hek293T cells was cytoplasmic, and some differences in cytoskeleton interactions have been evidenced. Moreover, in Hek293T cells only the transfected 1BLCTS isoform gives rise to a large intracytoplasmic cylindrical structure containing phalloidin-positive amorphous actin aggregates. The presence of eight full-length Arg isoforms with different cellular expression may imply a diverse functional role in normal and neoplastic cells.