Sperm capacitation and its relationship with sperm microRNAs profile and fertility in Nellore bulls

• Grant number: 20/14918-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): August 01, 2022
• Effective date (End): August 31, 2023
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Eneiva Carla Carvalho Celeghini
• Grantee: Laura Nataly Garcia Oliveros
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Sperm capacitation is key to successful fertilization and involves cellular and molecular events. Sperm microRNAs, although they have an outstanding role in the molecular regulation of fertility in cattle, their role in the regulation of sperm capacitation is still unknown. Thus, this project aims to: (1) study the relationship between sperm capacitation and the profile of microRNAs in bulls; and (2) study the influence of microRNAs involved in sperm capacitation on the fertility of cryopreserved semen. For this, two experiments were designed. In experiment 1, four ejaculates from five bulls (n=20) will be evaluated for morphofunctional characteristics (volume, concentration, motility, morphology, plasma, acrosomal and mitochondrial membranes) and then divided into two samples. A semen sample will be divided into two treatments: induction (CAP) or not (Control; CON) to in vitro capacitation; while the other sample will be subjected to cryopreservation and after thawing also divided into two treatments: induction (CRICAP) or not (CRICON) to in vitro capacitation. After each treatment, spermatozoa will be evaluated for sperm capacitation events by the characteristics of membrane lipid fluidity, tyrosine phosphorylation, plasma membrane changes, lipid peroxidation, phosphatidylserine translocation, motility hyperactivation, and acrosomal reaction, and the profile of microRNAs. In experiment 2, three batches of semen from 10 high (n=30) and 10 low fertility (n=30) bulls will be evaluated for morphofunctional characteristics and divided into two treatments: in vitro capacitation induction (ACAP and BCAP) and not (ACON and BCON), being evaluated for sperm capacitation events for cryopreserved semen (experiment 1) and the abundance of mature microRNAs and their signaling pathways. Data will be evaluated through analysis of variance by the SAS program. The target genes and signaling pathways of microRNAs will be analyzed by the TargetScan and Metaboanalyst platforms, respectively. It is expected to find sperm microRNAs related to sperm capacitation differently detected in groups of high and low fertility bulls. In this way, the study will open new avenues for the identification of samples with high fertile potential.Keywords: sperm, tyrosine phosphorylation, plasma membrane, hyperactivation, acrosomal reaction, cryopreservation.