Showing papers by "Gregory A. Johnson published in 2015"

Amino acids and conceptus development during the peri-implantation period of pregnancy.

Abstract: The dialogue between the mammalian conceptus (embryo/fetus and associated membranes) involves signaling for pregnancy recognition and maintenance of pregnancy during the critical peri-implantation period of pregnancy when the stage is set for implantation and placentation that precedes fetal development. Uterine epithelial cells secrete and/or transport a wide range of molecules, including nutrients, collectively referred to as histotroph that are transported into the fetal-placental vascular system to support growth and development of the conceptus. The availability of uterine-derived histotroph has long-term consequences for the health and well-being of the fetus and the prevention of Developmental Origins of Health and Disease (DOHAD). Although mechanisms responsible for differential growth and development of the conceptus resulting in DOHAD phenomena remain unclear, epigenetic events involving methylation of DNA are likely mechanisms. Histotroph includes serine and methionine which can contribute to the one carbon pool, and arginine, lysine and histidine residues which may be targets of methylation. It is also clear that supplementing the diet with arginine enhances fetal-placental development in rodents, swine and humans through mechanisms that remain to be elucidated. However, molecules secreted by conceptuses such as interferon tau in ruminants, estrogens and interferons in pigs and chorionic gonadotrophin, along with progesterone, regulate expression of genes for nutrient transporters. Understanding mechanisms whereby select nutrients regulate expression of genes in cell signaling pathways critical to conceptus development, implantation and placentation is required for improving successful establishment and maintenance of pregnancy in mammals.

Aquaporins in the female reproductive system of mammals.

Abstract: Water and ion accumulation is the driving force for rapid expansion of the amnion and allantois of mammalian placentae during early gestation, and, therefore, essential for embryonic/fetal growth and survival. Aquaporins (AQP) are a family of small integral plasma membrane proteins that primarily transport water across the plasma membrane. To date, thirteen AQP isoforms (AQP 0-12) have been identified in mammals. AQP 1, 2, 3, 4, 5, 6, 7, 8, 9, and 11 are expressed in the female reproductive tract. Based on their structural and functional properties, AQPs are divided into three subgroups: classical aquaporins (AQP 0, 1, 2, 4, 5, 6, and 8), aquaglyceroporins (AQP 3, 7, 9, and 10), and superaquaporins (AQP 11 and 12). Expression of AQPs in the uterus and placenta is regulated by hormones and nutrients to maintain fluid homeostasis in the conceptus. The underlying mechanisms may involve signal transduction pathways mediated by cAMP, MAPK, PKC, and PI3K/Akt/mTOR. Such new knowledge will advance basic understanding of mammalian reproductive biology to enhance embryonic/fetal survival, growth and development in women and livestock.

Implantation and Establishment of Pregnancy in the Pig.

Abstract: Establishment of pregnancy in the pig is initiated through the release of estrogens from the rapidly elongating conceptuses. Release of estrogens from the developing conceptuses alters the movement of endometrial prostaglandin F2α from being released into the vasculature (endocrine secretion) to sequestering in the uterine lumen (exocrine secretion). Rapid trophoblast elongation, which is unique to the pig, may be triggered through production of interleukin 1β2 (IL1B2) by conceptuses. Trophoblast elongation through the uterine horns provides the mechanism to allow conceptus–endometrial interactions essential for the implantation, placentation, and maintenance of pregnancy in the pig. This chapter provides current information on conceptus signaling pathways and endometrial responses to those conceptus factors leading to establishment of pregnancy.

Proteome Differences in Placenta and Endometrium between Normal and Intrauterine Growth Restricted Pig Fetuses

Abstract: Uteroplacental tissue plays a key role in substance exchanges between maternal and fetal circulation, and, therefore, in the growth and development of fetuses. In this study, proteomics and western blotting were applied to investigate the changes of proteome in the placenta and endometrium of normal and intrauterine growth restriction (IUGR) porcine fetuses during mid to late pregnancy (D60, 90, and 110 of gestation). Our results showed that proteins participating in cell structure, energy metabolism, stress response, cell turnover, as well as transport and metabolism of nutrients were differentially expressed in placenta and endometrium between normal and IUGR fetuses. Analysis of functions of these proteins suggests reductions in ATP production and nutrients transport, increases in oxidative stress and apoptosis, and impairment of cell metabolism in IUGR fetuses. Collectively, our findings aid in understanding of the mechanisms responsible for uteroplacental dysfunction in IUGR fetus, and are expected to provide new strategies to reduce fetal growth restriction in pigs and other mammals.