Characterization and imprinting analysis of COPG2 and MEST genes in pigs

MEST and COPG2 in human MEST imprinted cluster are two of good candidate genes responsible for primordial growth retardation including Silver–Russell syndrome. In order to increase understanding of these genes in pigs, their cDNAs are characterized in this report. By real-time quantitative RT-PCR and polymorphism-based method, tissue and allelic expression of both genes were determined using F1 reciprocal Landrace × Rongchang pig crossbreds. The transcription levels of MEST differed between tissues and decreased as development proceeded. The gene was imprinted and paternally expressed in heart, stomach, skeletal muscle, kidney, lung, bladder,tongue and fat, while biallelic expression was detected in liver, small intestine and spleen of onemonth-old pigs. The porcine COPG2 was differentially expressed between neonatal tissues and showed biallelic expression in postnatal tissues. Furthermore, the transcript of COPG2 in bladder and small intestine increased with age. It is concluded that tissue expression of porcine MEST is similar to, while COPG2 differs from other mammalian homologues. In addition, porcine MEST has development-specific imprinting, but imprinting of COPG2 in mammals is controversial.