Mapping of the testis gene and contribution to the study of its expression.

Summary Proteoglycans are macromolecules composed of a protein backbone on which are covalently bound particular polysaccharide chains, the glycosaminoglycans. Their role is associated with fundamental cellular processes: proliferation, adhesion and cell migration. In our laboratory, a peptide carrying chondroitin and heparan sulfate chains was isolated from human seminal plasma. The complementary dna generating this peptide was cloned, allowing the establishment of the complete deduced protein sequence of a new molecule, testis. A clone with a 112 bp insertion in the coding phase of the molecule and a shortened 3' non-coding region was characterized. The reality of this transcript was demonstrated by rt-pcr and the alternative exon coding for this insertion was characterized. The complete mapping of this gene and its chromosomal location have been established. The human testis is encoded by a single gene, located on chromosome 5q band 31 and is composed of twelve exons, for a size estimated at more than 100kb. Northern blot analysis on a representative set of human tissues revealed a majority messenger rna of 5.2kb, in the genital tract and particularly in the prostate. An antibody directed against the n-terminal region of the testis was performed. An immunohistochemical analysis allowed to localize the testis in the prostatic epithelial tissue, privileged target of neoplasia. This expression was confirmed by in situ hybridization, in healthy and cancerous tissues, for both types of transcripts. In a set of seven pathological tissues, a western analysis revealed, in only one case, a protein with unexpected electrophoretic mobility. An analysis of the gene of this patient, suffering from a severe form of hormone-independent prostate cancer, allowed to characterize, on one of the alleles, a 19 bp deletion in the alternatively spliced exon.