Caprine pregnancy-associated glycoproteins (PAG): Their cloning, expression, and evolutionary relationship to other PAG

Abstract

Pregnancy‐associated glycoproteins (PAG) are structurally related to aspartic proteinases and belong to an extensive, rapidly evolving family of recently duplicated genes expressed in the placentas of artiodactyl species. The aim of the present study was to clone PAG from the goat, study their temporal and cell‐specific expression, and determine their phylogenetic relationship to PAG from other species. RT‐PCR was used to generate PAG cDNA from pooled placental RNA obtained between days 45 and 115 of pregnancy. A total of 11 cDNA, which differed by > 5% from each other, were selected for complete bidirectional sequencing from 60 clones analyzed. A group of nine (caPAG1, caPAG3–7var, caPAG9–11), which displayed > 80% sequence identity with each other, were expressed after day 45 of pregnancy and were localized to trophoblast binucleate cells. These PAG demonstrated an unusually high ratio of nonsynonymous (amino acid changing) to synonymous nucleotide differences. CaPAG2, by contrast, was detectable only in early pregnancy (days 18 and 19) and expressed throughout trophectoderm. It was of more ancient origin than the PAG1 group, but more recent than caPAG8. The latter was expressed at all stages examined (days 18 to 115). The data confirm that many PAG genes, with different patterns of temporal and spatial expression, are transcribed in the placenta of the goat. The data also suggest that the recently duplicated PAG genes are being selected for rapid diversification of function. Mol. Reprod. Dev. 57:311–322, 2000. © 2000 Wiley‐Liss, Inc.

Isolation and characterization of eight pregnancy-associated glycoproteins present at high levels in the ovine placenta between day 60 and day 100 of gestation

“…It is novel in that the studies were completed at a stage of gestation that has yet to be examined. Our study confirmed one of the most interesting features of PAGs, the switching of gene expression [13,21]. Some PAG are thought to be expressed first and then to be replaced at a later time by others.…”

Acid peptidase activity released from in vitro produced porcine embryos: A candidate marker to predict developmental competence

“…The PAGs represent a large gene family and are expressed in a host of other species such as cattle, sheep, goats, etc. (Xie et al, 1991;Garbayo et al, 2000;Green et al, 2000). Proteins somewhat related to this class are expressed in rodents (Chen et al, 2001) and equids (Green et al, 1998(Green et al, , 1999.…”

Pregnancy – associated glycoproteins as a new diagnostic tool in cattle reproduction

“…These molecules are synthesized by the mono-and binucleate trophoblastic cells and released into maternal blood starting from first weeks of pregnancy until delivery. PAGs are already detectable in placental tissue around the time of implantation Garbayo et al, 2000;Green et al, 2000;Wooding et al, 2005).…”

“…From a scientific and economic side it was a progression in the breeding of those animals. PAGs are synthesized in the outer epithelial cell layer (chorion/trophectoderm) of the placenta Green et al, 1998;Garbayo et al, 2000). Part of the molecules traffics into maternal blood and milk (Tainturier et al, 1996;Gajewski et al, 1999;Metelo et al, 2002;Lopez-Gatius et al, 2007;Gajewski et al, 2008a;Gajewski et al, 2008b).…”