Cysteine Analogs with a Free Thiol Group Promote Fertilization by Reducing Disulfide Bonds in the Zona Pellucida of Mice1

Abstract

Archives of cryopreserved sperm harvested from genetically engineered mice, in mouse resource centers, are a readily accessible genetic resource for the scientific community. We previously reported that exposure of oocytes to reduced glutathione (GSH) greatly improves the fertilization rate of frozen-thawed mouse sperm. Application of GSH to in vitro fertilization techniques is widely accepted as a standard protocol to produce sufficient numbers of mice from cryopreserved sperm. However, the detailed mechanism of the enhancement of fertilization mediated by GSH in vitro is not fully understood. Here we focused on the chemical by determining the effects of its amino acid constituents and cysteine analogs on the fertilization of oocytes by frozen-thawed sperm. Furthermore, we determined the stability of these compounds in aqueous solution. We show here that l-cysteine (l-Cys), d-cysteine (d-Cys), or N-acetyl-l-cysteine (NAC) increased the rate of fertilization when added to the medium but did not adversely affect embryo development in vitro or in vivo. The levels of thiol groups of proteins in the zona pellucida (ZP) and the expansion of the ZP were increased by l-Cys, d-Cys, and NAC. These effects were abrogated by the methylation of the thiol group of l-Cys. NAC was the most stable of these compounds in the fertilization medium at 4°C. These results suggest that the thiol groups of cysteine analogs markedly enhance the fertilization rate of mouse oocytes.

Effects of Supplementation with Natural Antioxidants on Oocytes and Preimplantation Embryos

“…In contrast with previous findings, two trials conducted by Murto et al failed to associate folic acid intake or good folate plasma status, together with MTHFR gene variations, to a better pregnancy outcome following infertility treatment [ 72 , 73 ]. In accordance with Murto et al [ 72 , 73 ] data, a prospective cohort study of 602 women undergoing infertility treatment, did not find association between folate and vitamin B 12 levels and likelihood of a successful pregnancy [ 74 ].…”

“…β-carotene resulted helpful in in vitro studies in promoting the cytoplasmic maturation of oocytes [ 105 , 106 ], but there is a lack of clinical data on female fertility and, as supplementation, on IVF outcomes. Folates and vitamin B 12 are the most studied B-vitamins in the human field in the context of IVF procedures [ 70 , 71 , 72 , 73 , 74 ], but sufficient evidence to support clinicians in making a decision is still lacking. The need to expand data also applies to vitamin D supplementation.…”

Leucine mediates autophagosome-lysosome fusion and improves sperm motility by activating the PI3K/Akt pathway

“…In addition, arginine, glutamic acid and methionine were found in the semen of several fish species where sperm motility was improved when spermatozoa were co-incubated with methionine [ 3 , 4 ]. In mouse, cysteine analogs can increase the fertilization of frozen-thawed sperms [ 5 ]. Hence, some essential amino acids are likely to be involved in the sperm motility of teleost fishes.…”

Preparation of GST Inhibitor Nanoparticle Drug Delivery System and Its Reversal Effect on the Multidrug Resistance in Oral Carcinoma

“…This carrier material was used as the polymer material to prepare the nanoparticles, and the PEG on its surface may ensure the nanoparticles to retain their EPR and enable them to reach to the focus as soon as possible through the venous blood [ 21 , 22 , 23 ]. The ECA with disulfide bonds designed in this study was aimed at the dissociation of ECA in the highly expressed GSH environment in tumor cells to make the ECA exert its effect as a GST inhibitor to reduce the multidrug resistance of tumor cells [ 24 , 25 ]. Due to more active groups of the ECA, the synthetic reaction at the ECA end should be minimized as far as possible.…”