ALTERNATIVE SPLICING OF PSP94 (PROSTATIC SECRETORY PROTEIN OF 94 AMINO-ACIDS) MESSENGER-RNA IN PROSTATE TISSUE

While performing reverse transcriptase-polymerase chain reaction (RT-P CR) analysis of total mRNA from prostate cancer specimens, two forms o f PSP94 cDNA were detected, RT-PCR products were analysed by Southern blotting and probing with exon-specific oligonucleotides, In the short form of PSP94 mRNA, designated as PSP57, exon III was found to be del eted, The two mRNA forms were confirmed by cloning and sequencing of t he RT-PCR products and were found to result from alternative splicing, The alternatively spliced form, PSP57, was characterized by sequence analysis, PSP94 and PSP57 possess identical exons I and II, including identical secretion signal peptide and the 5' untranslated sequences, PSP57 has a frame-shifted exon IV and encodes a putative 57 amino acid protein with a navel, highly basic C-terminus of 41 amino acids, PSP5 7 mRNA was detected in other urogenital tissues (kidney, bladder) and in most tumor cell lines tested, but was not detectable in other tissu es such as breast and lung, In prostate tumor cell lines, PSP57 mRNA w as aberrantly spliced and localized in the nuclear fraction of the cel l, Our results suggest the possible existence of a novel PSP protein t hat originates from alternative splicing of PSP94 mRNA in urogenital t issues.