SUMMARYUbiquitination is essential for protein degradation and signaling and pivotal to many physiological processes. Ubiquitination of a subset of G-protein-coupled receptors (GPCRs) by the E3 ligase NEDD4–2 is required for p38 activation, but how GPCRs activate NEDD4–2 to promote ubiquitinmediated signaling is not known. Here, we report that the GPCR protease-activated receptor-1 (PAR1) stimulates c-Src-mediated tyrosine phosphorylation and activation of NEDD4–2 to promote p38 signaling and endothelial barrier disruption. Using mass spectrometry, we identified a unique phosphorylated tyrosine (Y)-485 within the 2,3-linker peptide between WW domain 2 and 3 of NEDD4–2 in agonist-stimulated cells. Mutation of NEDD4–2 Y485 impaired E3 ligase activity and failed to rescue PAR1-stimulated p38 activation and endothelial barrier permeability. The purinergic P2Y1 receptor also required c-Src and NEDD4–2 tyrosine phosphorylation for p38 activation. These studies reveal a novel role for c-Src in GPCR-induced NEDD4–2 activation, which is critical for driving ubiquitin-mediated p38 inflammatory signaling.

Abnormal uterine activity in pregnancy causes a range of important clinical disorders, including preterm birth, dysfunctional labour and post-partum haemorrhage. Uterine contractile patterns are controlled by the generation of complex electrical signals at the myometrial smooth muscle plasma membrane. To identify novel targets to treat conditions associated with uterine dysfunction, we undertook a genome-wide screen of potassium channels that are enriched in myometrial smooth muscle. Computational modelling identified Kir7.1 as potentially important in regulating uterine excitability during pregnancy. We demonstrate Kir7.1 current hyper-polarizes uterine myocytes and promotes quiescence during gestation. Labour is associated with a decline, but not loss, of Kir7.1 expression. Knockdown of Kir7.1 by lentiviral expression of miRNA was sufficient to increase uterine contractile force and duration significantly. Conversely, overexpression of Kir7.1 inhibited uterine contractility. Finally, we demonstrate that the Kir7.1 inhibitor VU590 as well as novel derivative compounds induces profound, long-lasting contractions in mouse and human myometrium; the activity of these inhibitors exceeds that of other uterotonic drugs. We conclude Kir7.1 regulates the transition from quiescence to contractions in the pregnant uterus and may be a target for therapies to control uterine contractility.

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Phosphorylation at distinct sites determines the effect of the chaperone protein HSP27 on endothelial barrier permeability.

Despite some significant differences in the first-trimester serum levels of angiogenic factors, our models suggest that these factors are not clinically useful for prediction in women who later developed PE.

Harrod JS, Rada CC, Pierce SL, England SK, Lamping KG. Altered contribution of RhoA/Rho kinase signaling in contractile activity of myometrium in leptin receptor-deficient mice. Am J Physiol Endocrinol Metab 301: E362-E369, 2011. First published May 10, 2011 doi:10.1152/ajpendo.00696.2010.-In late gestation, enhanced myometrial contractility is mediated in part through increased Rho/Rho kinase. Since leptin, which is elevated in pregnancy and obesity, can directly depress myometrial function, we hypothesized that in leptin receptor-deficient mice, myometrial contractility would be greater in late pregnancy due to increased Rho/Rho kinase activity. To test this, we correlated RhoA and Rho kinase expression to contractility in myometrium from nonpregnant (NP) and late-pregnant (P18) heterozygous leptin receptor-deficient mice (db/ϩ) vs. wild-type (WT) mice. In NP mice, KCl-induced contractions were similar between WT and db/ϩ myometrium. However, the Rho kinase-dependent component of the contractions was greater in db/ϩ mice, along with an increased expression of Rho kinase. KCl-induced contractions increased in strength in myometrium from P18 WT and db/ϩ compared with NP. Although the contribution of Rho kinase to contractions was unchanged in P18 WT mice, it was decreased in P18 db/ϩ mice. The decrease in Rho kinase-dependent contractions in P18 db/ϩ mice coincided with reduced RhoA and Rho kinase expression relative to NP db/ϩ. Addition of high-fat-induced abnormal glucose utilization prevented changes in Rho kinase function. We conclude that abnormal leptin signaling increases expression and function of Rho kinase to maintain contractile function in NP myometrium and that during pregnancy the contribution of RhoA and Rho kinase expression to myometrial function is reduced despite an increase in myometrial contractility. Thus, other signaling mechanisms appear to compensate when leptin signaling is reduced to maintain contractile function during pregnancy. pregnancy; obesity; gestational diabetes CURRENTLY IN THE US, one in five pregnant women is obese, which is associated with increased perinatal mortality and morbidity and a fivefold increase in the average cost of prenatal care and hospital stay (12,20,28). Maternal complications in both overweight and obese women include development of gestational diabetes (GDM), preeclampsia, increased miscarriages and preterm births, poor labor progression, and failed spontaneous term deliveries (15,28,44). Because of the failure to deliver spontaneously in obese mothers, the number of postterm labor inductions and cesarean deliveries is high. The increased number of cesarean sections cannot be explained by an increased infant birth weight (44). These pregnancy-associated complications observed in obese women suggest that maternal obesity has a significant impact on myometrium, which is due possibly to abnormal uterine smooth muscle function. This notion is supported by the finding that both the force and frequency of spontaneous contractions are markedly decreased in my...

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. Despite the discovery of key regulators of uterine contractility, this process is still not fully understood. Transgenic mice provide an ideal model in which to study parturition. Previously, the only method to study uterine contractility in the mouse was ex vivo isometric tension recordings, which are suboptimal for several reasons. The uterus must be removed from its physiological environment, a limited time course of investigation is possible, and the mice must be sacrificed. The recent development of radiometric telemetry has allowed for longitudinal, realtime measurements of in vivo intrauterine pressure in mice. Here, the implantation of an intrauterine telemeter to measure pressure changes in the mouse uterus from mid-pregnancy until delivery is described. By comparing differences in pressures between wild type and transgenic mice, the physiological impact of a gene of interest can be elucidated. This technique should expedite the development of therapeutics used to treat myometrial disorders during pregnancy, including preterm labor. Video LinkThe video component of this article can be found at

Rada CC, Pierce SL, Nuno DW, Zimmerman K, Lamping KG, Bowdler NC, Weiss RM, England SK. Overexpression of the SK3 channel alters vascular remodeling during pregnancy, leading to fetal demise. Am J Physiol Endocrinol Metab 303: E825-E831, 2012. First published July 11, 2012; doi:10.1152/ajpendo.00165.2012.-The maternal cardiovascular system undergoes hemodynamic changes during pregnancy via angiogenesis and vasodilation to ensure adequate perfusion of the placenta. Improper vascularization at the maternalfetal interface can cause pregnancy complications and poor fetal outcomes. Recent evidence indicates that small conductance Ca 2ϩ -activated K ϩ channel subtype 3 (SK3) contributes to vascular remodeling during pregnancy, and we hypothesized that abnormal SK3 channel expression would alter the ability of the maternal cardiovascular system to adapt to pregnancy demands and lead to poor fetal outcomes. We investigated this hypothesis using transgenic Kcnn3 tm1Jpad /Kcnn3 tm1Jpad (SK3 T/T ) mice that overexpress the channel. Isolated pressurized uterine arteries from nonpregnant transgenic SK3 T/T mice had larger basal diameters and decreased agonist-induced constriction than those from their wild-type counterparts; however, non-receptor-mediated depolarization remained intact. In addition to vascular changes, heart rates and ejection fraction were increased, whereas end systolic volume was reduced in SK3 T/T mice compared with their wild-type littermates. Uterine sonography of the fetuses on pregnancy day 14 showed a significant decrease in fetal size in SK3 T/T compared with wild-type mice; thus, SK3 T/T mice displayed an intrauterine growth-restricted phenotype. The SK3 T/T mice showed decreased placental thicknesses and higher incidence of fetal loss, losing over half of their complement of pups by midgestation. These results establish that the SK3 channel contributes to both maternal and fetal outcomes during pregnancy and point to the importance of SK3 channel regulation in maintaining a healthy pregnancy.small conductance Ca 2ϩ -activated K ϩ channel subtype 3; pregnancy; vasculature SUCCESSFUL PREGNANCY REQUIRES rapid and diverse changes in maternal cardiovascular physiology to ensure appropriate blood flow through the placenta (20). Dynamic changes in maternal heart rate, stroke volume, venous pressure, blood volume, and systemic vascular resistance result from formation of new blood vessels at the maternal-fetal interface and dilation of existing vessels (1). These adaptive changes are essential for providing oxygen and nutrients for, as well as eliminating waste from, the fetus. In humans, hemodynamic changes start at ϳ3 wk of gestation, with maximal variations from the nonpregnant state beginning in the second trimester. These two phases of hemodynamic change correlate temporally with common time frames for miscarriage and fetal loss. In mice, changes in heart rate and mean arterial pressure can be detected in the mother as early as pregnancy days 6 -8 compared with nonpregnant states (5). In both mice a...