The gene TSGA14, adjacent to the imprinted gene MEST, escapes genomic imprinting

We identified the gene TSGA14, encoding the testis-specific protein A14 and located 50 kb proximal to the imprinted gene MEST in a head-to-head orientation. TSGA14 has at least two transcripts: a long-type (l-type) transcript, and a short-type (s-type) transcript. Since the COPG2IT1 gene in the vicinity of MEST has been reported to be imprinted, we presumed that TSGA14 might also be imprinted. We thus analyzed the imprinting status of TSGA14 l-type and s-type transcripts in various fetal tissues. TSGA14 l-type transcript, which consists of 11 exons and encodes a l-type isoform with 373 amino acids, is biallelically expressed in the fetal tissues including the testis. TSGA14 s-type transcript, which consists of three exons and encodes a s-type isoform with 54 amino acids, also showed biallelic expression in the fetal brain and liver. No allele-specific methylation in the TSGA14 CpG island was detected. The fact that COPG2 and TSGA14, both neighbors of MEST, escape genomic imprinting suggests that the 7q32 imprinted region may be small and not similar to other imprinted domains, such as those at 15q11-13 and 11p15.5.