Identification of Two Major Histocompatibility Complex Class Ib Genes, Q7 and Q9, as the Ped Gene in the Mouse1

Abstract

The Ped (preimplantation embryonic development) gene influences the rate of preimplantation embryonic development and subsequent embryonic survival. The protein product of the Ped gene, the Qa-2 protein, is a major histocompatibility complex (MHC) class Ib protein. There are two alleles of the Ped gene, fast (Qa-2 [+]) and slow (Qa-2 [-]). Qa-2 is encoded by four very similar MHC class Ib genes: Q6, Q7, Q8, and Q9. Recent research in our laboratory has shown that the Ped phenotype is potentially encoded by the Q7 and/or Q9 gene because the Q7 and Q9 genes, but not the Q6 or Q8 gene, are expressed during preimplantation mouse embryonic development. In this study we utilized microinjection of transgenes to assess the functional roles of both the Q7 and Q9 genes in control of the rate of preimplantation development. The Q7 gene, the Q9 gene, and a combination of the Q7 and Q9 genes were microinjected into Ped slow zygotes, and the Ped phenotype and cell surface expression of Qa-2 protein were assayed after a 72-h or 96-h incubation period. We found that the microinjected individual Q7 and Q9 genes increased the rate of preimplantation development. Simultaneous injection of the Q7 and Q9 genes did not have a synergistic effect on the Ped phenotype. Microinjection of the Q7 and/or Q9 genes resulted in protein expression in 10-25% of the microinjected embryos. These results show that both the Q7 and Q9 genes encode the mouse Ped phenotype.

Mouse oocytes and preimplantation embryos bear the two sub‐units of interferon‐gamma receptor

“…Indeed it modulates the expression of the mouse preimplantation embryonic development (Ped) genes (actually the Q7 and/or Q9 MHC class I genes), which govern the swiftness of preimplantation development (McElhinny et al, 1998;Wu et al, 1999). A similar mechanism seems to operate in humans, the nonclassical MHC class I gene, HLA-G, being a possible homologue of the mouse Ped gene (Jurisicova et al, 1996).…”

Influence of the Preimplantation Embryo Development (Ped) Gene on Embryonic Platelet-Activating Factor (PAF) Levels

“…The Ped gene also has a role in blastocyst differentiation (7). The product of the Ped gene, the Qa-2 protein, is a mouse major histocompatibility complex (MHC) class Ib protein encoded by two almost identical genes (one nucleotide difference), Q7 and Q9 (6,8). However, other genes, in addition to the MHC encoded Ped, gene, play a role in the control of the rate of early preimplantation embryonic cleavage (9).…”

Early transcription from the maternal genome controlling blastomere integrity in mouse two-cell-stage embryos

“…The Ped gene, a class Ib MHC component called the Qa-2 antigen (a glycosylphosphatidylinositol-linked cell surface protein encoded in the Q region of the mouse MHC), is associated with enhanced cleavage rate, larger blastocyst cell numbers, and greater midgestation survival (34,48,(53)(54)(55)(56). Previous reports concluded that the Ped phenotype is directed by the Q7 or Q9 genes, because Q6 and Q8 expression was undetected by RT-PCR (58,59). Our data indicate that the expression of H2-Q8 is low but detectable on arrays, leaving open the possibility that this gene may affect early cleavage rate.…”