Gene editing to investigate the role of conceptus factors in the establishment of pregnancy in the pig

Abstract

Development of viviparity in mammals required that the placenta evolve as an intermediate interface between the fetus and maternal uterus. In addition to the retention of the fetus and secretion of nutrients to support growth and development to term, it was essential that viviparous species modify or inhibit the maternal immune system from recognizing the semi-allogeneic fetus. Following blastocyst hatching from its zona pellucida, trophoblast differentiation provides the initial communication to the maternal endometrium to regulate maintenance of progesterone production from the corpus luteum and biological pathways in uterine and conceptus development necessary in establishment and maintenance of pregnancy. Many conceptus factors have been proposed to serve in the establishment and maintenance of pregnancy. CRISPR-Cas9 gene editing technology provides a specific and efficient method to generate animal models to perform loss of function studies to investigate the role of specific conceptus factors. The utilization of CRISPR-Cas9 gene editing has provided a direct approach to investigate the specific role of conceptus factors in development and establishment of pregnancy in the pig. This technology has helped address a number of questions concerning peri-implantation development and altered our understanding of maternal recognition and maintenance of pregnancy in the pig.

Metabolic pathways utilized by the porcine conceptus, uterus, and placenta

“…Nevertheless, elongation and implantation are used to describe the initial stages of placental development in pigs. Although the duration of the preimplantation period is prolonged in the pig, and the type of implantation differs from that of many other species, the initial stages of implantation are common across species and are characterized as the “adhesion cascade for implantation” (Geisert et al, 2021; Johnson et al, 2014; Waclawik et al, 2017; Zang et al, 2021; Zeng et al, 2019). This adhesion cascade begins with shedding of the zona pellucida, followed by elongation of the conceptus trophectoderm.…”

Revisiting the Transcriptome Landscape of Pig Embryo Implantation Site at Single-Cell Resolution

“…It has long been proposed that conceptus production of interleukin 1 beta 2 (IL1B2), estrogen (E 2 ), prostaglandin E2 (PGE2) and interferon gamma (IFNG) are critical for conceptus development and implantation. Recently, CRISPR-Cas9 gene-editing technology provides an easy way to test these hypothesis by performing loss-of-function studies in the pig conceptus ( Geisert et al, 2021 ). Inactivation of IL1B2 resulted in failure of rapid conceptus elongation ( Whyte et al, 2018 ).…”

Mechanisms regulating the initiation of porcine conceptus elongation

“…Scale bar = 10 mm. approaches (i.e., transcriptomics, proteomics, and metabolomics) to identify deviations of entire pathways on a comprehensive scale, and more recently CRISPR-Cas9 technologies that utilize specific loss-offunction studies to study specific conceptus factors (Geisert et al, 2021), there has been a significant increases in the understanding of the biological processes that regulate the entirety of conceptus elongation.…”

“…Although crosstalk is primarily throught to occur between the uterine endometrium and conceptus during elongation (Ostrup et al, 2011), recent evidence has demonstrated crosstalk mechanisms between the trophectoderm and embryo proper during elongation, illustrating potential paracrine signaling between various cell types of the conceptus to stimulate and progress through elongation (Geisert et al, 2014; Jeong et al, 2016; Valdez Magana et al, 2014). With recent advancement of scientific technology, particularly ‐omics approaches (i.e., transcriptomics, proteomics, and metabolomics) to identify deviations of entire pathways on a comprehensive scale, and more recently CRISPR‐Cas9 technologies that utilize specific loss‐of‐function studies to study specific conceptus factors (Geisert et al, 2021), there has been a significant increases in the understanding of the biological processes that regulate the entirety of conceptus elongation.…”