Use of DNA array to screen blastocyst genes potentially involved in the process of murine implantation

Conceptus implantation to the mother's uterus is a complex series of events involving coordinated expression of numerous genes at both the embryonic and the uterine sides. Since there are no suitable in vivo or in vitro experimental models, sequential changes occurring during the peri-implantation periods have not been well characterized. Using GeneChip technology and a recently introduced murine in vitro model of implantation, the expression of embryonic genes was examined before and after attachment to the uterine stromal cells. Instead of RNA or mRNA, amplified cRNA was subjected to the GeneChip analysis because amounts of mRNA in each blastocyst were minimal. Among 6,500 gene transcripts examined, changes in mRNA levels for 802 genes were identified. Of these detections, transcripts previously unsuspected were changes in a group of tumor suppressor and stress-induced genes, whose transcripts increased as embryos attached to the membrane. Validity of the data was evaluated using reverse transcription-polymerase chain reaction and in situ hybridization analyses, both of which confirmed developmental changes in selected gene expressions during pre- and post-attachment periods. The present data suggest that GeneChip technology would be very useful for finding genes previously unsuspected, and this method should be used as an initial step, particularly as a screening tool, toward the dissection of complex mechanisms such as the processes of implantation.