Lipopolysaccharides selectively inhibit mouse placental lactogen-II secretion through stimulation of interleukin-1 alpha (IL-1 alpha) and IL-6 production

Genes and signals regulating murine trophoblast cell development

A fundamental step in embryonic development is cell differentiation whereby highly specialised cell types are developed from a single undifferentiated, fertilised egg. One of the earliest lineages to form in the mammalian conceptus is the trophoblast, which contributes exclusively to the extraembryonic structures that form the placenta. Trophoblast giant cells (TGCs) in the rodent placenta form the outermost layer of the extraembryonic compartment, establish direct contact with maternal cells, and produce a number of pregnancy-specific cytokine hormones. Giant cells differentiate from proliferative trophoblasts as they exit the cell cycle and enter a genome-amplifying endocycle. Normal differentiation of secondary TGCs is a critical step toward the formation of the placenta and normal embryonic development. Trophoblast development is also of particular interest to the developmental biologist and immunobiologist, as these cells constitute the immediate cellular boundary between the embryonic and maternal tissues. Abnormalities in the development of secondary TGCs results in severe malfunction of the placenta. Herein we review new information that has been accumulated recently regarding the molecular and cellular regulation of trophoblast and placenta development. In particular, we discuss the molecular aspects of murine TGC differentiation. We also focus on the role of growth and transcription factors in TGC development.

Murine serum cytokines throughout the estrous cycle, pregnancy and post partum period

Cytokines are pleiotropic glycoproteins participating in many aspects of mammalian reproductive physiology. Although murine models have been established to study normal and pathological pregnancy, the small volume of retrievable sample has hampered investigations into the role of cytokines in these processes. These problems were overcome by using fluid-phase multiplex immunoassays to monitor the serum profiles of 18 cytokines in single animals throughout normal murine reproduction: estrus, diestrus, post coitum, preimplantation, implantation, mid-pregnancy, late pregnancy and post partum. Most cytokines were detectable throughout all stages studied. Modest changes in profile were associated with estrous cyclicity and early pregnancy while virtually all cytokine levels increased markedly in mid- to late pregnancy and either fell slightly or levelled off post partum. The functional interrelationships between the various cytokines and the hormonal milieu are discussed with respect to gestational stage. Although certain profiles supported the 'conventional' Th1:Th2 cytokine paradigm of pregnancy, many of the changes recorded were orchestrated around IL-12 (p40) and (p70). The present findings suggest that the traditional cytokine dichotomy poorly describes complex immunological processes like pregnancy.

Calcyclin in the mouse decidua: expression and effects on placental lactogen secretion

Placental lactogens are protein hormones produced by the placentas of many mammals. These hormones have diverse reproductive functions and are structurally similar to the pituitary hormones growth hormone and prolactin. Isolated decidual cells were previously shown to release a protein that stimulates mouse placental lactogen (mPL)-II release from mouse trophoblast cells in culture. Partial amino acid sequence data suggested that this protein shared sequence identity with mouse calcyclin. In the present study the sequence identity of this protein was determined by sequencing reverse transcription-polymerase chain reaction (RT-PCR) products. The sequence matched that of mouse calcyclin. The distribution of calcyclin message was determined in the conceptus by in situ hybridization, and a gestational profile of calcyclin mRNA was determined by Northern blot analysis. Calcyclin was localized primarily to cells that exhibited a uterine natural killer cell morphology within the decidua and to glycogen cells of the labyrinth and junctional zone. Although calcyclin was detectable by RT-PCR in midterm placentas, isolated trophoblast cells in culture did not contain detectable quantities of calcyclin by RT-PCR. Calcyclin stimulated secretion of mPL-II from isolated trophoblast cells in vitro but did not affect mPL-I secretion.