Site-Specific Cleavage by Topoisomerase 2: A Mark of the Core Centromere.

In addition to its roles in transcription and replication, topoisomerase 2 (topo 2) is crucial in shaping mitotic chromosomes and in ensuring the orderly separation of sister chromatids. As well as its recruitment throughout the length of the mitotic chromosome, topo 2 accumulates at the primary constriction. Here, following cohesin release, the enzymatic activity of topo 2 acts to remove residual sister catenations. Intriguingly, topo 2 does not bind and cleave all sites in the genome equally; one preferred site of cleavage is within the core centromere. Discrete topo 2-centromeric cleavage sites have been identified in α-satellite DNA arrays of active human centromeres and in the centromere regions of some protozoans. In this study, we show that topo 2 cleavage sites are also a feature of the centromere in Schizosaccharomyces pombe, the metazoan Drosophila melanogaster and in another vertebrate species, Gallus gallus (chicken). In vertebrates, we show that this site-specific cleavage is diminished by depletion of CENP-I, an essential constitutive centromere protein. The presence, within the core centromere of a wide range of eukaryotes, of precise sites hypersensitive to topo 2 cleavage suggests that these mark a fundamental and conserved aspect of this functional domain, such as a non-canonical secondary structure.

Forms of Circulating Luteinizing Hormone Human Chorionic Gonadotropin Receptor for the Prediction of Early and Late Preeclampsia in the First Trimester of Pregnancy.

OBJECTIVE: To explore the value of circulating luteinizing human chorionic gonadotropin receptor (LHCGR) forms for the prediction of preeclampsia (PE) in the first trimester of pregnancy. METHODS: Case-control study, based on a cohort of 5,759 pregnancies, including 20 early PE, 20 late PE, and 300 controls. We recorded/measured maternal characteristics, mean arterial pressure (MAP), uterine artery (UtA) Doppler, placental growth factor (PlGF), soluble Fms-like tyrosine kinase-1 (sFtl-1), and LHCGR forms (hCG-LHCGR and soluble LHCGR), and their independent predictive values were analyzed by logistic regression. RESULTS: For early PE, the model included black ethnicity, chronic hypertension, previous PE, MAP, UtA Doppler, PlGF, sFlt-1, and LHCGR forms, achieving detection rates (DR) of 83% at 10% of false-positive rates (FPR) [AUC: 0.961 (95% CI: 0.921-1)]. For late PE, the model included body mass index, previous PE, UtA Doppler, PlGF, sFlt-1, and LHCGR forms, with DR of 75% at 10% of FPR [AUC: 0.923 (95% CI: 0.871-0.976)]. In both early and late PE, LHCGR forms improved DR by 6-15%. CONCLUSIONS: LHCGR forms improved the prediction for early and late PE. These results should be confirmed in larger prospective studies.

The utility of circulating LHCGR as a predictor of Down's syndrome in early pregnancy.

BACKGROUND: Previous studies showed that soluble LHCGR/hCG-sLHCGR concentrations in serum or plasma combined with PAPP-A and free ßhCG significantly increased the sensitivity of Down's syndrome screen at early pregnancy without altering the false positive rate. The goal of the present study was to further examine the role of sLHCGR forms as combinatorial markers and to investigate whether sLHCGR could serve as an independent biomarker for Down's syndrome in first trimester pregnancy screens. METHODS: The PAPP-A, free ßhCG, and hCG-sLHCGR concentrations together with nuchal translucency (NT) were measured in 40 Down's and 300 control pregnancies. The sLHCGR concentration was analysed in 40 Down's and 206 control pregnancies. RESULTS: The hCG-LHCGR in combination with PAPP-A and free ßhCG increased the detection rate (DR) by 35% without altering the false positive rate (FPR). The sLHCGR: hCG-sLHCGR ratio alone detected 80% of Down's pregnancies in first trimester screening, with a false positive rate of 0.5%. CONCLUSIONS: While measurement of sLHCGR forms in combination with PAPP-A and free ßhCG significantly increases the detection rate of Down's syndrome at first trimester, the ratio of sLHCGR: hCG-sLHCGR acts as an independent marker with a detection rate that is significantly higher than the existing biochemical markers individually for prenatal first trimester screening of Down's syndrome.

Age-dependent female responses to a male ejaculate signal alter demographic opportunities for selection.

A central tenet of evolutionary explanations for ageing is that the strength of selection wanes with age. However, data on age-specific expression and benefits of sexually selected traits are lacking-particularly for traits subject to sexual conflict. We addressed this by using as a model the responses of Drosophila melanogaster females of different ages to receipt of sex peptide (SP), a seminal fluid protein transferred with sperm during mating. SP can mediate sexual conflict, benefitting males while causing fitness costs in females. Virgin and mated females of all ages showed significantly reduced receptivity in response to SP. However, only young virgin females also showed increased egg laying; hence, there was a narrow demographic window of maximal responses to SP. Males gained significant 'per mating' fitness benefits only when mating with young females. The pattern completely reversed in matings with older females, where SP transfer was costly. The overall benefits of SP transfer (hence opportunity for selection) therefore reversed with female age. The data reveal a new example of demographic variation in the strength of selection, with convergence and conflicts of interest between males and ageing females occurring over different facets of responses to a sexually antagonistic trait.

Quantitative ELISAs for serum soluble LHCGR and hCG-LHCGR complex: potential diagnostics in first trimester pregnancy screening for stillbirth, Down's syndrome, preterm delivery and preeclampsia.

BACKGROUND: Soluble LH/hCG receptor (sLHCGR) released from placental explants and transfected cells can be detected in sera from pregnant women. To determine whether sLHCGR has diagnostic potential, quantitative ELISAs were developed and tested to examine the correlation between pregnancy outcome and levels of serum sLHCGR and hCG-sLHCGR complex. METHODS: Anti-LHCGR poly- and monoclonal antibodies recognizing defined LHCGR epitopes, commerical anti-hCGbeta antibody, together with recombinant LHCGR and yoked hCGbeta-LHCGR standard calibrators were used to develop two ELISAs. These assays were employed to quantify serum sLHCGR and hCG-sLHCGR at first trimester human pregnancy. RESULTS: Two ELISAs were developed and validated. Unlike any known biomarker, sLHCGR and hCG-sLHCGR are unique because Down's syndrome (DS), preeclampsia and preterm delivery are linked to both low (less than or equal to 5 pmol/mL), and high (equal to or greater than 170 pmol/mL) concentrations. At these cut-off values, serum hCG-sLHCGR together with PAPP-A detected additional DS pregnancies (21%) which were negative by free hCGbeta plus PAPP-A screening procedure. Therefore, sLHCGR/hCG-sLHCGR has an additive effect on the current primary biochemical screening of aneuploid pregnancies. More than 88% of pregnancies destined to end in fetal demise (stillbirth) exhibited very low serum hCG-sLHCGR(less than or equal to 5 pmol/mL) compared to controls (median 16.15 pmol/mL, n = 390). The frequency of high hCG-sLHCGR concentrations (equal to or greater than 170 pmol/mL) in pathological pregnancies was at least 3-6-fold higher than that of the control, suggesting possible modulation of the thyrotropic effect of hCG by sLHCGR. CONCLUSIONS: Serum sLHCGR/hCG-sLHCGR together with PAPP-A, have significant potential as first trimester screening markers for predicting pathological outcomes in pregnancy.

Circulating LH/hCG receptor (LHCGR) may identify pre-treatment IVF patients at risk of OHSS and poor implantation.

BACKGROUND: Successful pregnancy via in vitro fertilization (IVF) depends on the recovery of an adequate number of healthy oocytes and on blastocyst implantation following uterine transfer. Two hormones, LH and hCG, utilize a common LH/hCG receptor (LHCGR), variations in which have profound implications in human reproduction. Soluble LHCGR (sLHCGR) is released from experimental cell lines and placental explants and it can be detected in the follicular fluid and serum. METHODS: To evaluate the impact of circulating soluble LHCGR (sLHCGR) in fertility treatment, we measured sLHCGR and LH-sLHCGR complex in serum from women seeking IVF using specifically developed quantitative enzyme-linked immunosorbent assays (ELISA). Following an IVF cycle of treatment, patients were grouped according to oocyte yield into low (lower than or equal to 7 oocytes), intermediate (8-14 oocytes) and high (greater than or equal to 15 oocytes) responders and pregnancy outcome noted. RESULTS: Pre-treatment sLHCGR identified many women at risk of ovarian hyperstimulation. Low levels of sLHCGR were associated with pregnancy in both high and low responders but sLHCGR did not significantly affect the treatment outcome of intermediate responders. Low responders who failed to become pregnant had high levels of circulating sLHCGR bound to LH (LH-sLHCGR). CONCLUSIONS: Pre-treatment measurement of sLHCGR could be used to tailor individual fertility treatment programs and improve outcomes by avoiding ovarian hyperstimulation and poor embryo implantation.