Genes of cellular components of morphogenesis in porcine oocytes before and after IVM

Abstract

Proper oocyte maturation in mammals produces an oocyte capable of monospermic fertilization and embryo preimplantation. The cumulus-oocyte complexes (COCs), surrounding an oocyte, play a significant role in oocyte maturation. During this process, when the COCs undergo cumulus expansion wherein tightly compact cumulus cells (CCs) form a dispersed structure, permanent biochemical and molecular modifications occur in the maturing oocytes, indicating that the gene expression between immature and mature oocytes differs significantly. This study focuses on the genes responsible for the cellular components of morphogenesis within the developing oocyte. Brilliant cresyl blue (BCB) was used to determine the developmental capability of porcine oocytes. The immature oocytes (GV stage) were compared with matured oocytes (MII stage), using microarray and qRT-PCR analysis to track changes in the genetic expression profile of transcriptome genes. The data showed substantial upregulation of genes influencing oocyte's morphology, cellular migration and adhesion, intracellular communication, as well as plasticity of nervous system. Conversely, downregulation involved genes related to microtubule reorganization, regulation of adhesion, proliferation, migration and cell differentiation processes in oocytes. This suggests that most genes recruited in morphogenesis in porcine oocyte may have cellular maturational capability, since they have a higher level of expression before the oocyte's matured form. It shows the process of oocyte maturation and developmental capacity is orchestrated by significant cellular modifications during morphogenesis.

Significant Down-Regulation of “Biological Adhesion” Genes in Porcine Oocytes after IVM

“…These nuclear alterations, contributing to organelles reorganization in mammalian oocytes, both in vivo and in vitro, still need further investigation. As we showed previously [ 8 , 9 , 10 , 11 , 23 ], transcriptomic profile of gene expression differs significantly in porcine oocytes before and after IVM. Thus, to improve the quantity of mature and fertilizable oocytes, as well as IVF outcome, finding new molecular markers of maturation capability is highly recommended [ 24 , 25 , 26 , 27 ].…”

“…It was well recognized in several species of mammals that only properly structuralized mature oocyte (MII) may be successfully fertilized by spermatozoon, and each stage of early folliculogenesis and oogenesis influences further embryo growth and development [ 5 , 6 , 7 ]. Our previous experiments indicated an increased expression of genes involved in “Bone development”, “Cellular components of morphogenesis”, “BMP signaling pathway”, and “Cell migration”, which were intensively regulated during in vitro maturation of porcine oocytes (IVM) [ 8 , 9 , 10 , 11 , 12 ].…”

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.…”

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

“…In porcine oocytes, the vast majority of genes recruited in morphogenesis can affect cell maturation as compared to mature oocytes. This means, that during morphogenesis, the process of oocyte maturation and developmental capacity are regulated by cellular modifications [20].…”