Renju S. Raj

Implantation Failure in Female Kiss1−/− Mice Is Independent of Their Hypogonadic State and Can Be Partially Rescued by Leukemia Inhibitory Factor

The hypothalamic kisspeptin signaling system is a major positive regulator of the reproductive neuroendocrine axis, and loss of Kiss1 in the mouse results in infertility, a condition generally attributed to its hypogonadotropic hypogonadism. We demonstrate that in Kiss1(-/-) female mice, acute replacement of gonadotropins and estradiol restores ovulation, mating, and fertilization; however, these mice are still unable to achieve pregnancy because embryos fail to implant. Progesterone treatment did not overcome this defect. Kiss1(+/-) embryos transferred to a wild-type female mouse can successfully implant, demonstrating the defect is due to maternal factors. Kisspeptin and its receptor are expressed in the mouse uterus, and we suggest that it is the absence of uterine kisspeptin signaling that underlies the implantation failure. This absence, however, does not prevent the closure of the uterine implantation chamber, proper alignment of the embryo, and the ability of the uterus to undergo decidualization. Instead, the loss of Kiss1 expression specifically disrupts embryo attachment to the uterus. We observed that on the day of implantation, leukemia inhibitory factor (Lif), a cytokine that is absolutely required for implantation in mice, is weakly expressed in Kiss1(-/-) uterine glands and that the administration of exogenous Lif to hormone-primed Kiss1(-/-) female mice is sufficient to partially rescue implantation. Taken together, our study reveals that uterine kisspeptin signaling regulates glandular Lif levels, thereby identifying a novel and critical role for kisspeptin in regulating embryo implantation in the mouse. This study provides compelling reasons to explore this role in other species, particularly livestock and humans.

Influenza, immune system, and pregnancy.

Influenza is a major health problem worldwide. Both seasonal influenza and pandemics take a major toll on the health and economy of our country. The present review focuses on the virology and complex immunology of this RNA virus in general and in relation to pregnancy. The goal is to attempt to explain the increased morbidity and mortality seen in infection during pregnancy. We discuss elements of innate and adaptive immunity as well as placental cellular responses to infection. In addition, we delineate findings in animal models as well as human disease. Increased knowledge of maternal and fetal immunologic responses to influenza is needed. However, enhanced understanding of nonimmune, pregnancy-specific factors influencing direct interaction of the virus with host cells is also important for the development of more effective prevention and treatment options in the future.

Impact of Experimental Diabetes on the Maternal Uterine Vascular Remodeling During Rat Pregnancy

Normal pregnancy is associated with an increase in uteroplacental blood flow in part due to growth and remodeling of the maternal uterine vasculature. In this study, we characterized the effect of diabetic pregnancy on vascular growth of the maternal uterine vasculature and on the passive mechanical properties of the uterine resistance arteries. Diabetes was induced in pregnant rats by injection of streptozotocin and confirmed by development of hyperglycemia. Fetuses of diabetic rats were significantly smaller and placentas larger compared to controls. Pregnancy-induced axial elongation of the mesometrial uterine vasculature was not altered by diabetes. Vascular wall thickness was unchanged between groups. Wall distensibility was increased and the rate constant of an exponential function fitted to stress–strain curve was significantly reduced demonstrating decreased wall stiffness in diabetic uterine radial arteries compared to controls. We conclude that experimental diabetes in rat pregnancy does not compromise the growth of maternal uterine vasculature but alters passive mechanical properties of the uterine radial arteries.

Regulators of Ovarian Preantral Follicle Development

Preantral follicle development has become an increasingly recognized area of study in the last two decades. Factors that regulate the growth survival and differentiation of these small, yet complex structures have been identified. The field of fertility preservation and a need for increased numbers of mature oocytes for stem cell research revealed how little we knew of how follicles got from the primordial stage to the antral stage with a healthy and competent oocyte inside. This work discusses the role of gonadotropins in regulating preantral follicles and also the role of the TGF-β family members and their associated Smad signaling molecules in preantral follicle development. Preantral follicle development is a necessary step to fertility in females and further understanding of this process is essential for progress in both infertility care and the enlarging field of in vitro folliculogenesis.

Generalized Disturbance of DNA Methylation in the Uterine Decidua in the CBA/J × DBA/2 Mouse Model of Pregnancy Failure

ABSTRACT Nonchromosomal pregnancy failure is a common but poorly understood phenomenon. Because recent data have suggested that epigenetic abnormalities such as abnormal placental DNA methylation may play a role in human pregnancy failure, we undertook experiments to test whether decidual and/or placental DNA methylation abnormalities are present in a mouse model of pregnancy failure. A large number of studies have shown that crosses between CBA/J female mice and DBA/2 males result in pregnancies with a high rate of failure/resorption, whereas other crosses with CBA/J females produce normal pregnancies. Although the CBA/J × DBA/2 mouse has frequently been used as a model for miscarriage, a detailed explanation for the pregnancy failure phenotype is lacking. We performed timed matings between CBA/J female and DBA/2 male mice as well as between DBA/2 female and CBA/J male mice. Decidual caps were isolated at Embryonic Day (E) 9.5 from both crosses, and a microarray-based method was used to comparatively assess genomic methylation at approximately 16 000 loci on mouse chromosome 7. In comparison with decidual caps from DBA/2 × CBA/J pregnancies, CBA/J × DBA/2 decidual caps were characterized by widely and apparently randomly disturbed methylation. In another set of analogous experiments, genomic methylation of placental DNA from E8.5 pregnancies was assessed using the same microarray-based method. This analysis revealed that in contrast to the decidua, placental DNA methylation from CBA/J × DBA/2 pregnancies was indistinguishable from that of normal controls. We conclude that abnormal DNA methylation in the uterine decidua likely plays a role in the CBA/J × DBA/2 model of pregnancy failure. To our knowledge, these experiments are the first to demonstrate that epigenetic abnormalities of the decidua are associated with pregnancy failure, and they set the stage for future efforts to understand the role of DNA methylation at the maternal-fetal interface.

Cost-Effectiveness of Single Embryo Transfers Relative to Higher Embryo Transfer Policies in Clinical Practice: A Population-Based Analysis

Objective To determine whether singleton live birth rates and avoided multiple gestations following single embryo transfers (or alternative transfer policies) justify their additional costs.

An Extra Arm May Impair the Open Hand

In the paper, “Inhibin Biosynthesis and Activity Are Limited by a Prodomain-Derived Peptide,” Walton et al (1) purport that processing of inhibin-α can result in a 43-amino acid pro-α peptide from an alternate cleavage site. This propeptide is projected to have an amphipathic α-helical structure that can wrap around the open hand or butterfly-shaped mature inhibin protein, thereby hindering inhibin association with β-glycan. The function of this proinhibin α-peptide is investigated as an inhibitor of mature inhibin action. The inhibins and activins are produced as prepro-proteins in which nonactive domains that are important to protein folding and dimerization of the molecules are cleaved, releasing the final active products. The β-subunits for inhibin and activin have only one classical cleavage site, but the α-inhibin subunit has another cleavage site between the pro-α-peptide and the N-peptide (Figure 1A). Uncleaved or incompletely cleaved inhibins have been described for many years as high-molecular-weight or big inhibins, with varying demonstrations of bioactivity (2,–4). A free α-subunit in association with the C portion, without the N portion, has also been described and is produced at high levels by a variety of normal and abnormal tissues (5, 6), but this is the first evaluation of a functional small prodomain cleavage peptide for inhibin. Figure 1. A, Inhibin precursor with the cleavage sites. Note the two cleavage sites on the α-subunit and the single cleavage site on the β-subunit. B, Inhibin A/B binding to β-glycan. C, Pro-α-peptide intercalating between inhibin ... The authors also noted some time ago that three hydrophobic amino acids in the prodomain of the inhibin α-subunit were critical to proper folding and secretion of mature inhibins (7). In that work they used mutagenesis evidence to propose a model of interaction of the N-terminal prodomain with a region near the C terminus of the proprotein to hold it in a coiled conformation that would allow the covalent bonds with the similarly held β-proprotein subunits and promote further processing. In that work they also proposed that the entire cleaved prodomain could remain associated with the active inhibin in a noncovalent way, such as the fact that the latency-associated peptide remains associated with TGFβ (8). In this work they have focused on the role of the small 43-amino acid propeptide. Not only do they demonstrate the necessity of cleavage of this promolecule from the N and C regions of inhibin for production of mature peptide to occur, but they also provide strong evidence for a role of this unassuming peptide in modulating the bioactivity of the mature inhibins. Yet it does not seem to interfere with activin activity. Thus, inhibin protein may come along with its own tiny inhibitor after processing, with the little associated prodomain peptide intercalating itself between the interface with inhibin A or B and the β-glycan receptor (Figure 1, B and C). Yet a function of β-glycan is to inhibit the activation of the activin receptor signaling cascade (9, 10). So the inhibitor is packaged with its own inhibitor, like a functional mini-me, providing direct modulation of inhibin function. This has profound implications biologically if this relationship is shown to occur in vivo. Activin action is already known to be tightly regulated on many levels, both directly and indirectly. From the expression of excess inhibin α-subunits (favoring inhibin production over activin), to follistatin or α-macroglobin binding, to production of inhibitory smads that can directly modulate the activin signaling cascade; the action of activin is tightly regulated in tissue-specific ways, and its effects are profoundly concentration and tissue specific (11, 12). Entry into this already complex system regulating activin, the action of a small amphipathic molecule that could be delivered to a specific site to block inhibin and thereby increase activin action and possibly result in increased unbound β-glycan may have great usefulness clinically and as a research tool across several overlapping fields of endocrinology.