Effects of all<i>-trans</i> retinoic acid on the <i>in vitro</i> maturation of camel (<i>Camelus dromedarius</i>) cumulus-oocyte complexes

Abstract

All- trans retinoic acid (RA) is a metabolite of vitamin A and has pleiotropic actions on many different biological processes, including cell growth and differentiation, and is involved in different aspects of fertility and developmental biology. In the current study, we investigated the effects of RA on camel ( Camelus dromedarius ) cumulus-oocyte complex in vitro maturation (IVM). IVM medium was supplemented with 0, 10, 20, and 40 µM RA. Application of 20 µM RA significantly reduced the proportion of degenerated oocytes and significantly improved oocyte meiosis and first polar body extrusion compared to the control and other experimental groups. Retinoic acid significantly reduced the mRNA transcript levels of apoptosis-related genes, including BAX and P53 , and reduced the BAX/BCL2 ratio. In addition, RA significantly reduced the expression of the Transforming growth factor beta (TGFβ) pathway-related transcripts associated with the actin cytoskeleton, ACTA2 and TAGLN ; however, RA increased TGFβ expression in cumulus cells. The small molecule SB-431542 inhibits the TGFβ pathway by inhibiting the activity of activin receptor-like kinases (ALK-4, ALK-5, and ALK-7); however, combined supplementation with RA during IVM compensated for the inhibitory effect of SB-431542 on cumulus expansion, oocyte meiosis I, and first polar body extrusion in activated oocytes. The current study shows the beneficial effects of RA on camel oocyte IVM and provides a model to study the multifunctional mechanisms involved in cumulus expansion and oocyte meiosis, particularly those involved in the TGFβ pathway.

Lipopolysaccharide and tumor necrosis factor‐alpha alter gene expression of oocytes and cumulus cells during bovine in vitro maturation

“…Of the 12 cumulus cell transcripts altered by LPS exposure only half increased, in contrast to oocyte transcript abundance in which 24 genes showed increased expression with exposure to LPS. Exposure to LPS decreased the abundance of cumulus cell transcript for the actin cytoskeleton gene, ACTA2 , in a similar manner in which retinoic acid decreased expression in cumulus cells of the camel whereas simultaneously promoting maturation of oocytes (Saadeldin et al, ). Fibroblast growth factor‐4 is involved in cell proliferation and developmental processes, and here transcript abundance of FGF4 decreased in cumulus cells following LPS exposure.…”

Effects of Short-Term Inhibition of Rho Kinase on Dromedary Camel Oocyte In Vitro Maturation

“…The degree of cumulus expansion was assessed at the end of IVM culture as described previously [8]. Briefly, cumulus layers were observed under a microscope and graded as 0, 1, or 2.…”

The Usefulness of Retinoic Acid Supplementation during In Vitro Oocyte Maturation for the In Vitro Embryo Production of Livestock: A Review

“…On the other hand, a higher level of AtRA (1000 nM) had no beneficial impacts on goat parthenogenetic blastocyst formation, embryonic division, or total cell counts [1]. Saadeldin et al [7] studied the influences of RA addition (10, 20, and 40 µM) on the in vitro maturation (IVM) of the cumulus-oocyte complex of camel ( Camelus dromedarius ); the addition of 20 µM RA led to a significant reduction in the percentage of degenerated oocytes and a marked improvement in the first polar body extrusion and oocyte meiosis compared to those in the control and other experimental groups. The authors attributed this improvement to the marked reduction in the mRNA transcript levels of apoptosis-related genes by RA.…”

“…In this line, it was reported that adding 5 nM 9-cisRA to the culture media of bovine oocytes had a beneficial influence on the cytoplasmic maturation of vitrified bovine oocytes and thus enhanced the oocyte developmental competence [34]. The presence of RA can enhance oocyte maturation through several mechanisms, including antioxidant efficacy [35]; mitogen-activated protein kinase phosphatases [36]; increased midkine expression, which inhibits the rate of apoptosis [2,37]; inhibition of tumor necrosis factor-α production [7]; upregulates luteinizing hormone receptor expression, and enhanced secretion of FSH [34,38] (Table 1).…”

“…Providing essential nutrients or survival factors to the maturation media has become a broadly applicable approach; this may have the advantages of enhancing in vitro oocyte competence and embryonic growth. In light of this, many approaches have been implemented to explore the impacts of different culture conditions enriched with antioxidants or vitamins on oocyte ripening and embryonic growth in different mammalian species [1,4,5,6,7]. The low efficiency of in vitro embryo production could be attributed to the lack of knowledge on different nutritional requirements for oocyte maturation and embryo development, ROS generation, the difference in time of cytoplasmic and nuclear maturation, the inferior characters of frozen semen, apoptosis, and/or the alteration of transcription gene expression [4,5,7].…”