Expression of genes associated with BMP signaling pathway in porcine oocytes before and after IVM – a microarray approach

Abstract

BackgroundThe full maturational capability of mammalian oocytes is accompanied by nuclear and cytoplasmic modifications, which are associated with proliferation and differentiation of surrounding cumulus cells. These events are regulated on molecular level by the expression of target genes involved in signal transduction pathways crucial for folliculogenesis and oogenesis. Transforming growth factor beta signaling includes several molecules that are involved in the regulation of oogenesis and embryo growth, including bone morphogenetic protein (BMP). However, the BMP-related gene expression profile in oocytes at different maturational stages requires further investigation.MethodsOocytes were isolated from pubertal crossbred Landrace gilts follicles, selected with a use of BCB staining test and analyzed before and after in vitro maturation. Gene expression profiles were examined using an Affymetrix microarray approach and validated by RT-qPCR. Database for Annotation, Visualization, and Integrated Discovery (DAVID) software was used for the extraction of the genes belonging to a BMP-signaling pathway ontology group.ResultsThe assay revealed 12,258 different transcripts in porcine oocytes, among which 379 genes were down-regulated and 40 were up-regulated. The DAVID database indicated a “BMP signaling pathway” ontology group, which was significantly regulated in both groups of oocytes. We discovered five up-regulated genes in oocytes before versus after in vitro maturation (IVM): chordin-like 1 (CHRDL1), follistatin (FST), transforming growth factor-beta receptor-type III (TGFβR3), decapentaplegic homolog 4 (SMAD4), and inhibitor of DNA binding 1 (ID1).ConclusionsIncreased expression of CHRDL1, FST, TGFβR3, SMAD4, and ID1 transcripts before IVM suggested a subordinate role of the BMP signaling pathway in porcine oocyte maturational competence. Conversely, it is postulated that these genes are involved in early stages of folliculogenesis and oogenesis regulation in pigs, since in oocytes before IVM increased expression was observed.

Fatty Acids Related Genes Expression Undergo Substantial Changes in Porcine Oviductal Epithelial Cells During Long-Term Primary Culture

“…Our previous studies revealed large set of genes influencing maturation capability of porcine oocytes. We know that the differences in gene expression before and after in vitro maturation (IVM) reflect changes in oocytes and its susceptibility for future fertilization [3][4][5]. This observation can result in development of molecular diagnostic of female gametes before proceeding to IVM.…”

Principais genes implicados na aquisição de competência oocitária

“…Embora os aspectos bioquímicos implicados neste processo ainda não estejam esclarecidos, evidências sugerem que a transição do estado transcricional inativo para ativo é determinada pelo remodelamento da cromatina (Li et al, 2010). Segundo Cho et al (2002), esta reconfiguração da cromatina é regulada por proteínas cuja síntese é estimulada pelo aumento intraoocitário de íons cálcio decorrente da fertilização.…”

“…Pelo contrário, através da síntese de fatores de crescimento, o oócito controla inúmeras funções das células da granulosa ao seu redor como proliferação, diferenciação, expressão de receptores, esteroidogênese, expansão do cumulus e, consequentemente, determina seu próprio desenvolvimento. Dentre os fatores parácrinos secretados pelo oócito considerados importantes peptídeos reguladores intraovarianos estão o GDF-9 e a BMP15 os quais pertencem à família dos fatores de crescimento transformante beta (TGFβ) e são codificados por genes específicos de mesma designação (Gilchrist et al, 2008;Gilchrist e Richani, 2013;Budna et al, 2017).…”

“…Já a BMP15 promove a ativação das proteínas SMAD 1/5 e 8 ao interagir com os receptores BMPRII e ALK6. Estas SMADs, por sua vez, quando fosforiladas se translocam para o núcleo aonde interagem com reguladores transcricionais e induzem a expressão de genes específicos implicados não apenas no processo de expansão do cumulus como também na oogênese e maturação oocitária em virtude da comunicação bidirecional (Gilchrist et al, 2008;Budna et al, 2017).…”

Cytoplasmic and nuclear maturation of oocytes in mammals – living in the shadow of cells developmental capability

“…Three main processes are distinguished in cytoplasmic maturation, including organelle movement, cytoskeleton reorganization and molecular maturation [10]. Different types of medium are supplemented by the addition of fetal calf serum (FCS), follicular fluid (FF) and other supplements in the form of gonadotropin hormones and growth factors are factors that enable maturity [11]. However, the oocytes obtained by culturing in vitro may not possess full growth potential, resulting in abnormal development of the embryo, which would then generate defects in the developing fetus.…”