Molecular aspects of mucin biosynthesis and mucus formation in the bovine cervix during the periestrous period

Abstract

Mucus within the cervical canal represents a hormonally regulated barrier that reconciles the need to exclude the vaginal microflora from the uterus during progesterone dominance, while permitting sperm transport at estrus. Its characteristics change during the estrous cycle to facilitate these competing functional requirements. Hydrated mucin glycoproteins synthesized by the endocervical epithelium form the molecular scaffold of this mucus. This study uses the bovine cervix as a model to examine functional groups of genes related to mucin biosynthesis and mucus production over the periestrous period when functional changes in cervical barrier function are most prominent. Cervical tissue samples were collected from 30 estrus synchronized beef heifers. Animals were slaughtered in groups starting 12 h after the withdrawal of intravaginal progesterone releasing devices (controlled internal drug releases) until 7 days postonset of estrus (luteal phase). Subsequent groupings represented proestrus, early estrus, late estrus, metestrus, and finally the early luteal phase. Tissues were submitted to next generation RNA-seq transcriptome analysis. We identified 114 genes associated with biosynthesis and intracellular transport of mucins, and postsecretory modifications of cervical; 53 of these genes showed at least a twofold change in one or more experimental group in relation to onset of estrus, and the differences between groups were significant (P < 0.05). The majority of these genes showed the greatest alteration in their expression in the 48 h postestrus and luteal phase groups.

Proteomes of the Female Genital Tract During the Oestrous Cycle

“…The viscosity of the cervical mucus is mainly due its high content of mucins, such as the mucins 5B and 5AC (13). During the menstrual cycle in humans, the cervical production of mucins peaks midcycle (42,43) and the transcription of several mucin genes in the cervix is also increased at estrus during the bovine oestrus cycle (14). Our results in the sheep show that the amount of mucins present in the inner cervical mucus also peaks at estrus.…”

“…The comparison of previously published transcriptomes (14,20,21,33,34) and tissue proteomes (23,25) in other models with the sheep luminal proteomes from this study provided some information about the possible secretory origin of many proteins, suggesting that the regulation of the protein abundance along the cycle may be associated to a significant extent with endocrine control of the expression of several genes.…”

“…We searched for these genes in seven studies of the transcriptome or proteome of the female tract during the cycle in other species. These include the transcriptome of the bovine cervix (14), the transcriptomes of the horse (21) and bovine (20) endometrium, the proteome of human endometrium (23,25), the transcriptome of bovine oviduct epithelial cells (34), and the proteome of porcine oviduct epithelial cells (33). A total of 59 proteins were found to be regulated similarly, i.e.…”

“…The main structural components of the cervical mucus are mucins, highly glycosylated, high-molecular-weight proteins assembled into a filamentous and viscous mesh (13). The transcription of the mucin genes is increased at oestrus in the bovine cervical epithelium (14). The amount of mucins and their level of glycosylation are expected to contribute to the viscosity of the mucus (11).…”

Relación entre características físicas y contenido iónico del moco cervical con el estado de preñez al inseminar vaquillonas a celo detectado s

“…El bajo nivel de potasio encontrado en nuestro trabajo, para vacas que resultaron preñadas, coincide con estudios anteriores en los que se evaluó el contenido de potasio en sangre y secreciones vaginales de bovinos, demostrando que la concentración de K sufre una disminución marcada en el momento mismo de la ovulación o inmediatamente antes de este suceso (Guay, 1996).Por otro lado, la carga iónica de las secreciones mucosas está asociada por fuerzas electroquímicas a las mucinas sulfatadas que componen al moco y esto genera una fuerza osmótica responsable de la atracción de moléculas de agua (Alliende et al, 2008;Pluta et al, 2012). En este sentido, y considerando la relación sodio potasio intra y extracelular de fundamental importancia en la fisiología, en las vacas preñadas tal relación (Na+/K+) resultó significativamente mayor que la encontrada en las hembras vacías, esto permite suponer que guardaría relación con un mayor volumen de agua haciendo que el moco se observe más líquido o filante como se comentó anteriormente.…”