Abstract
Peroxiredoxins (PRDXs) are expressed in the ovary and during ovulation. PRDX1 activity related to the immuno-like response during ovulation is unknown. We investigated the roles of Prdx1 on TLR4 and ERK1/2 signaling from the ovulated cumulus–oocyte complex (COC) using Prdx1-knockout (K/O) and wild-type (WT) mice. Ovulated COCs were collected 12 and 16 h after pregnant mare serum gonadotropin/hCG injection. PRDX1 protein expression and COC secretion factors (Il-6, Tnfaip6, and Ptgs2) increased 16 h after ovulated COCs of the WT mice were obtained. We treated the ovulated COCs in mice with LPS (0.5 μg/mL) or hyaluronidase (Hya) (10 units/mL) to induce TLR4 activity. Intracellular reactive oxygen species (ROS), cumulus cell apoptosis, PRDX1, TLR4/P38/ERK1/2 protein expression, and COC secretion factors’ mRNA levels increased in LPS- and Hya-treated COCs. The ERK inhibitor (U0126) and Prdx1 siRNA affected TLR4/ERK1/2 expression. The number and cumulus expansion of ovulated COCs by ROS were impaired in Prdx1 K/O mice but not in WT ones. Prdx1 gene deletion induced TLR4/P38/ERK1/2 expression and cumulus expansion genes. These results show the controlling roles of PRDX1 for TLR4/P38/ERK1/2 signaling activity in ovulated mice and the interlink of COCs with ovulation.
Highlights
Published: 30 August 2021Ovulation is a complex process initiated by a luteinizing hormone surge and cumulus cell (CC) expansion in cumulus–oocyte complexes (COCs) [1]
We examined the mRNA expression of toll-like receptor4 (TLR4)-derived immune-modulatory factors or COC secretion factors (Tnfaip6, Il-6, and protein (Tnfaip6) and cyclooxygenase-2 (Ptgs2)) in ovulated COCs with LPS or
We investigated the changes in TLR4-derived ERK1/2 signaling by Western blot analysis in COCs after siRNA Prdx1 transfection to determine ERK1/2 MAP kinase signal activation of the suppressive effects of Prdx1 gene expression by siRNA Prdx1 in ovulated COCs (Figure 4B)
Summary
Ovulation is a complex process initiated by a luteinizing hormone surge and cumulus cell (CC) expansion in cumulus–oocyte complexes (COCs) [1]. CCs express innate immune cell-related proteins and cytokines, Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Such as interleukin (Il-6) and tumor necrosis factor-alpha (TNFα). The impacts of PRDXs on ovulation have been identified, the controlling mechanisms of ROS production and TLR4-mediated signaling by PRDX1, as an antioxidant enzyme, have not been reported in the ovulation process or the ovulated COCs of mice. We thought that regulation of ROS production and oxidative stress by PRDX1 may play a significant role in the ovulation and secretion function of the CCs of ovulated COCs in WT mice.
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