Early embryonic death-associated changes in genome-wide gene expression profiles in the fetal placenta of the cow carrying somatic nuclear-derived cloned embryo

Successful somatic nuclear transfer-derived cloning has been reported in cattle; however, the cloned embryo is highly susceptible to death around day 60 of gestation leading to early embryonic loss. The early embryonic death is postulated to possibly arise in part from an atypical placentation. We have performed cDNA macroarray analysis using 3,353 of the previously cataloged 4,165 genes, in order to characterize the early embryonic death-associated changes in genome-wide gene expression profiles in the fetal placenta of the cow carrying somatic nuclear transfer-derived cloned embryo. A more marked difference in the expression profiles was observed between the fetal placentas of the cows with the cloned immotile embryo (CD) and with the cloned motile embryo (CL) or artificial insemination-derived motile embryo (AI), as compared to between the CL and AI placentas, suggesting an aberration of the expression profile in the CD placenta among the three placentas. Further, 291 and 77 genes showed more than twofold elevation and less than 50% reduction, respectively, in either or both of two CD (CD1 and CD2) placentas in comparison with the CL placenta, but no differential expression between the CL and AI placentas. The expression patterns of six genes in the AI, CL, and CD placentas were confirmed in an experiment with an additional sample for each of the three placentas. Among the placental genes showing the early embryonic death-associated changes of expression in the cow with the cloned embryo, IGF2 (elevated gene), and HBA1, HBA2, SPTB, and SPTBN1 genes (reduced gene) are intriguing in that the changes of expression in these genes were observed in an additional sample of CD placenta as well as the CD1 and CD2 placentas, and in that overexpression (for IGF2) and dysfunction or deficiency (for HBA1, HBA2, SPTB, and SPTBN1) result in embryonic lethality.