Oocyte Meiotic Competence in the Domestic Cat Model: Novel Roles for Nuclear Proteins BRD2 and NPM1

Abstract

To participate in fertilization and embryo development, oocytes stored within the mammalian female ovary must resume meiosis as they are arrested in meiotic prophase I. This ability to resume meiosis, known as meiotic competence, requires the tight regulation of cellular metabolism and chromatin configuration. Previously, we identified nuclear proteins associated with the transition from the pre-antral to the antral follicular stage, the time at which oocytes gain meiotic competence. In this study, the objective was to specifically investigate three candidate nuclear factors: bromodomain containing protein 2 (BRD2), nucleophosmin 1 (NPM1), and asparaginase-like 1 (ASRGL1). Although these three factors have been implicated with folliculogenesis or reproductive pathologies, their requirement during oocyte maturation is unproven in any system. Experiments were conducted using different stages of oocytes isolated from adult cat ovaries. The presence of candidate factors in developing oocytes was confirmed by immunostaining. While BRD2 and ASRGL1 protein increased between pre-antral and the antral stages, changes in NPM1 protein levels between stages were not observed. Using protein inhibition experiments, we found that most BRD2 or NPM1-inhibited oocytes were incapable of participating in fertilization or embryo development. Further exploration revealed that inhibition of BRD2 and NPM-1 in cumulus-oocyte-complexes prevented oocytes from maturing to the metaphase II stage. Rather, they remained at the germinal vesicle stage or arrested shortly after meiotic resumption. We therefore have identified novel factors playing critical roles in domestic cat oocyte meiotic competence. The identification of these factors will contribute to improvement of domestic cat assisted reproduction and could serve as biomarkers of meiotically competent oocytes in other species.

Proteomic analysis of fipronil-induced molecular defects in spermatozoa

“…2 A, 3 , and 5 ). ASRGL1 is an enzyme that catalyzes the hydrolysis of l -asparagine that was previously found to be expressed during oocyte development 41 and in the sperm tail of rats and humans. Hashemitabar et al 42 also found that ASRGL1 was highly expressed in cases of asthenozoospermia.…”

Transfer of Galectin-3-Binding Protein via Epididymal Extracellular Vesicles Promotes Sperm Fertilizing Ability and Developmental Potential in the Domestic Cat Model

“…After 26 h incubation, LGALS3BP protein inhibition was achieved by transfecting anti-LGALS3BP antibodies into COCs as previously described [ 57 , 58 ], using the Chariot peptide nanoparticle transfection reagent (Active motif, Carlsbad, CA, USA). Antibody-Chariot complexes were made according to manufacturer’s instructions.…”

Genomic Identification, Evolution, and Expression Analysis of Bromodomain Genes Family in Buffalo

“…This suggests that BRD may have a context-dependent function in cellular homeostasis. Moreover, BRD-containing proteins can regulate downstream gene expression, which makes them valuable targets for the study of fertility, neurological and immunological diseases, and cancer therapy [ 11 , 12 , 13 , 14 , 15 ].…”