AN ALTERNATIVE SPLICING PRODUCT OF THE LAMIN-A C GENE LACKS EXON-10/

Expression of the A-type lamins was studied in the lung adenocarcinoma cell line GLC-A1. A-type lamins, consisting of lamin A and C, are two products arising from the same gene by alternative splicing. Northern blotting showed in GLC-A1 a relatively low expression level of lamin C and an even lower expression level of lamin A as compared to other a denocarcinoma cell lines, Immunofluorescence studies revealed highly i rregular nuclear inclusions of lamin A, suggesting protein or gene exp ression abnormalities, Reverse transcriptase-polymerase chain reaction -based cDNA analysis followed by sequencing indicated the presence of an as yet unidentified alternative splicing product of the lamin A/C g ene. This product differs from lamin A by the absence of the 5' part o f exon 10 (90 nucleotides). Therefore we propose to designate this pro duct lamin A Delta 10. Deletion of the 30 amino acids encoded by exon 10 was predicted to result in a shift in pi of the protein from 7.4 to approximately 8.6, which was confirmed by two-dimensional immunoblott ing. mRNA analysis in a variety of cell lines, normal colon tissue as well as carcinomas demonstrated the presence of lamin A Delta 10 in al l samples examined, suggesting its presence in a variety of cell types .