Expression of retinol‐binding protein messenger RNA and retinoic acid receptors in preattachment bovine embryos

Abstract

In cattle, retinoic acid (RA) has been indirectly associated with developmental potential of the embryo. RA is transported by retinol-binding protein (RBP) and actions of RA are mediated by several subtypes of nuclear retinoic acid receptors (RAR). Bovine embryos, produced in vitro from oocytes harvested from ovaries collected at a local abattoir, were frozen in liquid nitrogen at the oocyte, 2-, 4-, 8-, 16 to 20-cell, morula, blastocyst, and hatched blastocyst stages. Employing reverse transcription polymerase chain reaction (RT-PCR) we investigated mRNA expression for RBP, RARalpha, RARbeta, RARgamma, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Total RNA was extracted from 25 pooled embryos at each stage and RT-PCR analysis was repeated thrice. GAPDH transcript was detected in all stages. Transcripts for RBP, RARalpha, and RARgamma were also detected in all stages from the oocyte through to the hatched blastocyst. Expression of RARbeta was not detected at any stage. Whole-mount immunohistochemistry was performed with intact and hatched blastocysts using polyclonal antibodies against RARalpha and RARgamma2 to investigate if these embryonic mRNAs were translated to the mature protein. Strong immunostaining was observed for both RARalpha and RARgamma2 in the inner cell mass and trophectoderm of intact and hatched blastocysts. Expression of mRNA for RBP, RARalpha, RARgamma, and of the RARalpha and RARgamma2 receptor proteins in the bovine embryo suggests that RA is likely to directly regulate gene expression during preimplantation development in that species.

Effects of retinoic acid on maturation of immature mouse oocytes in the presence and absence of a granulosa cell co-culture system

“…However, addition of RA to the granulosa co-culture could improve the maturation condition. This is probably arbitrated through a regulatory role on the microenvironment surrounding the immature oocytes by excretion of various meiosis-promoting factors within the culture medium [5,43,44]. Our results support the assumption that t-RA and granulosa cell co-cultures are two factors that enhance oocytes maturation ability.…”

Retinoid‐dependent mRNA expression and poly‐(A) contents in bovine oocytes meiotically arrested and/or matured in vitro

“…Recently, most of RA nuclear receptors, including RAR a and g, RXR a and b, retinaldehyde dehydrogenase, and peroxisome-proliferator activated receptor gamma (PPARg), were detected in bovine oocytes and embryos (Mohan et al, 2001(Mohan et al, , 2002, and in cumulus cells (Mohan et al, 2003). The oocyte's developmental competence is enhanced by retinoid support during oocyte intrafollicular growth in the cow (Shaw et al, 1995), sheep (Eberhardt et al, 1999), and gilt (Whaley et al, 1997;Whaley et al, 2000), as in rabbits that have high levels of vitamin A (Besenfelder et al, 1996).…”

Evidence for the Expression of Alcohol Dehydrogenase Class I Gene in Rat Uterus and Its Up-regulation by Progesterone

“…Locally synthesized RA may act on endometrial epithelial cells and endometrial stromal cells in an autocrine or paracrine fashion and induce the differentiation of endometrium for implantation. The expression of RARs and RXRs in early embryo and trophoblast cells is reported in several species [33][34][35][36][37]. RARs and RXRs are related to trophoblast invasion [38], hCG secretion [39] and trophoblast differentiation [33,40].…”