Genomic sequence analysis of the bovine male-enhanced antigen-1 (Mea-1) and differential localization of its transcripts and products during spermatogenesis.

The male-enhanced antigen-1 (Mea-1) gene was previously isolated from a bovine testicular cDNA library. In the present study, we cloned the full-length bovine genomic Mea-1 gene and compared this with the Mea-1 cDNA. The 1035-nucleotide bovine mRNA for Mea-1 (excluding the poly (A) tail) is encoded in three exons distributed over 3123 base pairs of the genome. Analysis of the 5' flanking sequence by primer extension mapping identified two main transcription start sites and several minor ones. The 5' region contained transcription-related sequences such as TATA/CAAT boxes, GC-rich regions, and several cis elements. When chloramphenicol acetyltransferase (CAT) activities of 5'-deleted clones were measured in CHO, TM4, and BALB/3T3 cells, a critical region for transcription was identified around -249 to -113 bp region from transcription start site. In situ hybridization and immunohistochemistry indicate that transcripts of the Mea-1 gene were localized in primary and secondary spermatocytes, and spermatids, but the protein products were detected only in spermatids. Intensive transcription of Mea-1 gene and specific localization of the gene product suggest that Mea-1 may play a important role in the late stage of spermatogenesis.