Uterine and placenta characteristics during early vascular development in the pig from day 22 to 42 of gestation.

Insufficient placenta development is one of the primary causes of fetal death and reduced fetal growth after 35 days of gestation. Between day 22 and 42 the placenta consists of a central highly vascular placenta (HVP), adjacent to the fetus, a less vascular placenta (LVP), on either side of the fetus, and necrotic tips (NT). The objective of this study was to comprehensively evaluate uterine-placenta characteristics during early gestation in the gilt and determine time points and physiological changes. Gilts (n=25) were artificially inseminated at first detection of estrus (day 0) and 24h later, and harvested at 22, 27, 32, 37 or 42 days of gestation. Litter size, 12.1±3.4, was similar for all days of gestation. Fetal and placenta weight increased with day of gestation. The greatest increase in placenta weight occurred between 37 and 42 days of gestation. The LVP zones had no measurable fold formation until day 27. Necrotic tips became apparent after 27 days of gestation. Unoccupied areas of the uterus developed folds with changes in endometrial cell size and morphology from day 32 to 42 of gestation. Limited changes occurred in either fetal growth or placenta weight from day 27 through 32 of gestation; however, significant morphological changes occur at the maternal-fetal interface, demonstrating the dynamic architecture of the developing porcine placenta during early gestation. This work establishes fundamental time points in placenta development corresponding to fetal growth and microfold formation that may influence fetal growth and impact fetal survival.

Subfertility linked to combined luteal insufficiency and uterine progesterone resistance.

Early pregnancy loss is common and can be caused by a range of factors. The Brown Norway (BN) rat exhibits reproductive dysfunction characterized by small litter size and pregnancy failure and represents a model for investigating early pregnancy loss. In this study, we investigated the establishment of pregnancy in the BN rat and gained insight into mechanisms causing its subfertility. Early stages of BN uteroplacental organization are unique. The BN primordial placenta is restricted in its development and correlates with limited BN uterine decidual development. BN uterine decidua was shown to be both structurally and functionally distinct and correlated with decreased circulating progesterone (P4) levels. Ovarian anomalies were also apparent in BN rats and included decreased ovulation rates and decreased transcript levels for some steroidogenic enzymes. Attempts to rescue the BN uterine decidual phenotype with steroid hormone therapy were ineffective. BN uteri were shown to exhibit reduced responsiveness to P4 but not to 17beta-estradiol. P4 resistance was associated with decreased transcript levels for the P4 receptor (Pgr), a P4 receptor chaperone (Fkbp4), and P4 receptor coactivators (Ncoa1 and Ncoa2). In summary, the BN rat exhibits luteal insufficiency and uterine P4 resistance, which profoundly affects its ability to reproduce.

The hinge region between two ubiquitin-like domains destabilizes recombinant ISG15 in solution.

Interferon-stimulated gene (ISG) 15 mediates antiviral responses and also is upregulated within the endometrium in response to the developing embryo during early pregnancy. Structurally, ISG15 resembles two ubiquitin domains (30% identical) that are separated by a hinge region. Recombinant (r) bovISG15 is not stable in solution. It was hypothesized that the hinge region contributed to the instability of rbovISG15. Within 24 h of dialysis, rbovISG15 formed complexes as detected by reducing and denaturing SDS-PAGE. However, chemical perturbations of cysteine prevented formation of rbovISG15 complexes over time. Furthermore, a site-directed mutant of rbovISG15 (Cys80Ser) was isomeric and more stable than rbovISG15. Neither wild-type nor mutant rbovISG15 was able to interact with the ISG15 E1 initiating enzyme, UBE1L, in an in vitro pull-down assay. Ovine (ov) ISG15 has three additional amino acids within the hinge region that were hypothesized to increase stability and the degree of interaction with UBE1L because of increased separation of the ubiquitin-like domains. Over time in solution, rovISG15 the level of rovISG15 secondary structure was diminished, whereas the Cys80Ser rovISG15 structure did not change. A GST-Cys80Ser rovISG15 fusion protein had increased structural stability and enhanced protein-protein interaction with UBE1L after dialysis for 48 h, when compared to the GST-rovISG15 fusion protein or rbovISG15. Models of bovISG15, Cys80Ser bovISG15, and ovISG15 were constructed, which confirmed that the hinge region between the two ubiquitin domains destabilizes rbovISG15 in solution.

Low blood ISG15 mRNA and progesterone levels are predictive of non-pregnant dairy cows.

ISG15 is induced by conceptus-derived interferon-tau in the endometrium on days 15-45 of pregnancy. It was hypothesized that pregnancy induces blood cell ISG15 gene expression and that low blood ISG15 mRNA levels provide an indication of non-pregnant cows on day 18. Blood was collected either on day 18 (n = 78) or on days 15-21, 25, and 32 (n = 21; serial collection) from dairy cows following artificial insemination (AI). Plasma progesterone concentration was determined using RIA. ISG15 mRNA levels were determined using real-time PCR. Pregnancy was diagnosed on day 32 using transrectal ultrasound. ISG15 mRNA levels increased after day 16, peaked at day 20 and then declined to day 16 levels by 32 days following AI. The average pregnancy rate was 43% based on blood cell ISG15 mRNA. The average pregnancy rate was 33% based on the transrectal ultrasound. Lower levels of ISG15 mRNA or progesterone during serial collections were 100% accurate in predicting non-pregnant cows based on day 32 transrectal ultrasound. However, detection of ISG15 mRNA yielded 78% accuracy in predicting pregnant cows, while progesterone yielded 58% accuracy. Average plasma progesterone based on pregnancy status according to ultrasound was consistently higher in pregnant (> 4 ng/ml) when compared with non-pregnant cows from days 15 to 32, except on day 16. It is concluded that detection of low blood ISG15 mRNA levels during serial collection from days 17 to 25 serves as an accurate indicator of cows that are not pregnant, thus allowing re-synchronization and insemination.

Isolation and sequence of an interferon-tau-inducible, pregnancy- and bovine interferon-stimulated gene product 15 (ISG15)-specific, bovine ubiquitin-activating E1-like (UBE1L) enzyme.

Bovine (bov) interferon-stimulated gene product 15 (ISG15) is produced in the endometrium in response to conceptus-secreted interferon (IFN)-tau. ISG15 conjugates to endometrial proteins through an enzymatic pathway that is similar to ubiquitinylation. Ubiquitin-activating enzyme 1-like protein (UBE1L) initiates enzymatic conjugation by forming a thioester bond with ISG15, thus preparing it for transfer to the next series of enzymes. The bovUBE1L has not been described. We hypothesized that bovUBE1L was induced by pregnancy and IFN-tau in the endometrium. A 110-kDa protein was purified from bovine endometrial (BEND) cells based on affinity with recombinant (r) glutathione S-transferase (GST)-ISG15. This protein was digested in gel with trypsin. Seven peptides were purified using HPLC, sequenced using liquid chromatography-mass spectroscopy-mass spectroscopy and found to share 43-100% identity with human UBE1L. The full-length bovUBE1L cDNA was isolated from a BEND cell cDNA library, sequenced, and found to share 83% identity with human UBE1L cDNA. Northern blot revealed two mRNAs that were detected in greater (P<0.05) concentrations in endometrium from Day 17-21 pregnant versus nonpregnant cows. Western blots using antihuman UBE1L antibody revealed a similar pattern of pregnancy-associated expression of UBE1L protein in the uterus. The bovUBE1L mRNA was localized, using in situ hybridization, primarily to glandular and luminal epithelium, with more diffuse localization to stroma of the endometrium from pregnant cows. Because bovUBE1L was purified through its interaction with rGST-ISG15 and shares significant amino acid and cDNA sequence identity with human UBE1L, it is concluded that it mediates conjugation of ISG15 to uterine proteins in response to the developing and attaching conceptus.