Dynamic Proteomic Profiles of In Vivo- and In Vitro-Produced Mouse Postimplantation Extraembryonic Tissues and Placentas1

Abstract

As the interface between the mother and the developing fetus, the placenta is believed to play an important role in assisted reproductive technology (ART)-induced aberrant intrauterine and postnatal development. However, the mechanisms underlying aberrant placentation remain unclear, especially during extraembryonic tissue development and early stages of placental formation. Using a mouse model, this investigation provides the first comparative proteomic analysis of in vivo (IVO) and in vitro-produced (IVP) extraembryonic tissues and placentas after IVO fertilization and development, or in vitro fertilization and culture, respectively. We identified 165 and 178 differentially expressed proteins (DEPs) between IVO and IVP extraembryonic tissues and placentas on Embryonic Day 7.5 (E7.5) and E10.5, respectively. Many DEPs were functionally associated with genetic information processing, such as impaired de novo DNA methylation, as well as posttranscriptional, translational and posttranslational dysregulation. These novel findings were further confirmed by global hypomethylation, and a lower level of correlation was found between the transcriptome and proteome in the IVP groups. In addition, numerous DEPs were involved in energy and amino acid metabolism, cytoskeleton organization and transport, and vasculogenesis and angiogenesis. These disturbed processes and pathways are likely to be associated with embryonic intrauterine growth restriction, an enlarged placenta, and impaired labyrinth morphogenesis. This study provides a direct and comprehensive reference for the further exploration of the placental mechanisms that underlie ART-induced developmental aberrations.

Morphologic and molecular changes in the placenta: what we can learn from environmental exposures

“…Approximately one quarter of the genes identified were dysregulated at both times. Similar to what was observed in gene expression changes (16), the altered proteins were associated with regulation of gene and protein expression, transport, hematopoiesis/angiogenesis, cytoskeleton, energy metabolism, and immunity (12). In human ART placenta, proteome analyses identified genes associated with membrane traffic, metabolism, nucleic acid processing, stress response, and cytoskeletal functions (12).…”

“…Similar to what was observed in gene expression changes (16), the altered proteins were associated with regulation of gene and protein expression, transport, hematopoiesis/angiogenesis, cytoskeleton, energy metabolism, and immunity (12). In human ART placenta, proteome analyses identified genes associated with membrane traffic, metabolism, nucleic acid processing, stress response, and cytoskeletal functions (12). Also, ART placentas have been shown to have significantly higher steroid metabolizing enzyme activity, resulting in a higher clearance capability (10,42).…”

“…Intriguingly, the procedure of transferring blastocyst stage embryos alone can increase overall placental weight, strongly sμggesting that relatively brief procedures can contribute to placental phenotypes (14). In addition to overall increased placental weight, mouse IVF placentas also exhibit disproportionate overgrowth of the junctional zone, a tissue that secretes factors that may influence the growth of the placental vasculature (12–16). This disproportion is observed in E12.5 IVF concepti, meaning this morphological change is already detectable soon after placental formation (16).…”

“…A global reduction in DNA methylation was detected in ART term mouse placentas using luminometric methylation assay (LUMA), an assay that measures the relative amount of global CpG methylation using methylation sensitive and methylation insensitive restriction enzymes (14). A global reduction in DNA methylation was also detected in ART extraembryonic tissues at E7.5 using methylated DNA immunoprecipitation (MeDIP) (12). Similar to results of imprinted genes, human ART placentas also demonstrate lower CpG methylation at select non-imprinted genes (31,38).…”

“…Sui and colleagues have conducted proteomic analyses of E7.5 and E10.5 extraembryonic tissues of ART mouse concepti (12). The majority of genes that were affected were downregulated by comparison with control placenta.…”