Fetal cortical transcriptomic changes after oxytocin induced aberrant uterine contractility
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ABSTRACT: We report changes in the fetal brain cortical transcriptome after oxytocin-induced aberrant uterine contractility using unbiased RNA-seq analysis.
Project description:Throughout most of pregnancy, uterine quiescence is maintained by increased progesterone receptor (PR) transcriptional activity, while spontaneous labor is initiated/facilitated by a concerted series of biochemical events that activate inflammatory pathways and negatively impact PR function. In this study, we uncovered a new regulatory pathway whereby miRNAs serve as hormonally-modulated and conserved mediators of contraction-associated genes in the pregnant uterus from mouse to human. Using miRNA and gene expression microarray analyses of uterine tissues, we identified a conserved family of miRNAs, the miR-200 family, that is highly induced at term in both mice and humans, as well as two coordinately downregulated targets, zinc finger E-box binding homeobox proteins, ZEB1 and ZEB2, which act as transcriptional repressors. We also observed upregulation of the miR-200 family and downregulation of ZEB1 and ZEB2 in two different mouse models of preterm labor. We further demonstrated that ZEB1 is directly upregulated by the action of P4/PR at the ZEB1 promoter. Excitingly, we observed that ZEB1 and ZEB2 inhibit expression of the contraction- associated genes, oxytocin receptor and connexin-43 and block oxytocin-induced contractility in human myometrial cells. Together, these findings implicate the miR-200 family and their targets ZEB1 and ZEB2 as novel progesterone/PR- mediated regulators of uterine quiescence and contractility during pregnancy and labor, and shed new light on the molecular mechanisms involved in preterm birth. RNA was purified from mouse myometrium (miRNeasy kit, Qiagen). miRNA microarray was performed (LC Sciences) on 18 biological replicates of murine myometrium at 15.5 dpc and an equal number of replicates at 18.5 dpc. Gene expression microarray assays were performed (UT Southwestern Medical Center) on the same 36 samples as detailed further in SI Materials and Methods.
Project description:Uterine contractile dysfunction leads to pregnancy complications such as preterm birth and labor dystocia. Progesterone is necessary to suppress uterine contractions to prevent premature labor. As humans maintain high levels of progesterone throughout parturition, a functional progesterone withdrawal hypothesis suggests that relative levels of myometrial progesterone receptor isoforms PGR-A and PGR-B switch at parturition, where PGR-B promotes a relaxed state and PGR-A result in increased uterine contractility. Our objective is to determine the effects of altered levels of PGR-B and PGR-A in the mouse myometrium on pregnancy and parturition using transgenic mouse models in which the relative levels of these isoforms are altered specifically in the myometrium. Overexpression of PGR-B is associated with a markedly increased gestational length compared to control mice. In both ex vivo and in vivo experiments, myometrium of PGR-B overexpressing mice have prolonged labor, a significant decrease in uterine contractility, and a high incidence of labor dystocia. Conversely, overexpression of PGR-A is associated with an increase in uterine contractility without a change in gestational length. Uterine RNAseq at mid-pregnancy identified isoform-specific downstream targets and genes that were commonly regulated by both PGR isoforms. Gene signature analyses further revealed that PGR-B promotes muscle relaxation and that PGR-A is pro-inflammation. High levels of PGR-B manifest a genetic profile of a blunted phospholipase C pathway that mediates oxytocin and angiotensin II induced muscle contraction. These findings provided in vivo support that PGR isoform levels determine distinct transcriptomic landscapes and pathways in myometrial function and labor.
Project description:Throughout most of pregnancy, uterine quiescence is maintained by increased progesterone receptor (PR) transcriptional activity, while spontaneous labor is initiated/facilitated by a concerted series of biochemical events that activate inflammatory pathways and negatively impact PR function. In this study, we uncovered a new regulatory pathway whereby miRNAs serve as hormonally-modulated and conserved mediators of contraction-associated genes in the pregnant uterus from mouse to human. Using miRNA and gene expression microarray analyses of uterine tissues, we identified a conserved family of miRNAs, the miR-200 family, that is highly induced at term in both mice and humans, as well as two coordinately downregulated targets, zinc finger E-box binding homeobox proteins, ZEB1 and ZEB2, which act as transcriptional repressors. We also observed upregulation of the miR-200 family and downregulation of ZEB1 and ZEB2 in two different mouse models of preterm labor. We further demonstrated that ZEB1 is directly upregulated by the action of P4/PR at the ZEB1 promoter. Excitingly, we observed that ZEB1 and ZEB2 inhibit expression of the contraction- associated genes, oxytocin receptor and connexin-43 and block oxytocin-induced contractility in human myometrial cells. Together, these findings implicate the miR-200 family and their targets ZEB1 and ZEB2 as novel progesterone/PR- mediated regulators of uterine quiescence and contractility during pregnancy and labor, and shed new light on the molecular mechanisms involved in preterm birth.
Project description:To gain insight into the mechanism(s) by which obesogenic diet caused decreased uterine contractility at term, we collected uterine tissue from mice fed either a control (CON) or an obesogenic (DIO) diet at day 18.5 of pregnancy and performed RNA sequencing.
Project description:Context: Increased uterine stretch appears to increase the risk of preterm labour, but the mechanism is unknown. Objectives: To identify a targetable mechanism mediating the effect of stretch on human myometrium. Design: Myometrial explants, prepared from biopsies obtained at elective caesarean delivery, were either studied acutely, or were maintained in prolonged culture (up to 65 h) under tension with either a 0.6 g or 2.4 g mass, and compared using in vitro contractility, whole genome array, and qRT-PCR. Results: Increased stretch for 24 or 65 h increased potassium-induced and oxytocin-induced contractility. Gene array identified 62 differentially expressed transcripts after 65 h exposure to increased stretch. Two probes for gastrin-releasing peptide (GRP), a known stimulatory agonist of smooth muscle, were among the top five up-regulated by stretch (3.4-fold and 2.0-fold). Up-regulation of GRP by stretch was confirmed in a separate series of 10 samples using qRT-PCR (2.8-fold, P = 0.01). GRP stimulated contractions acutely when added to freshly obtained myometrial strips in 3 out of 9 cases, but Western blot demonstrated expression of the GRP receptor in 9 out of 9 cases. Prolonged incubation of stretched explants in the GRP antagonists PD-176252 or RC-3095 (65 and 24 h respectively) significantly reduced potassium chloride and oxytocin-induced contractility. Conclusion: Stretch of human myometrium increases contractility and stimulates the expression of a known smooth muscle stimulatory agonist, GRP. Incubation of myometrium in GRP receptor antagonists ameliorates the effect of stretch. GRP may be a target for novel therapies to reduce the risk of preterm birth in multiple pregnancy. 9 paired samples of human myometrium cultured under low (0.6g) or high (2.4g) tension
Project description:Desensitization of the oxytocin receptor (OXTR) in the setting of prolonged oxytocin exposure may lead to dysfunctional labor, which increases the risk for cesarean delivery, and uterine atony, which may result in postpartum hemorrhage. The molecular mechanism for OXTR desensitization is through the agonist-mediated recruitment of the multifunctional protein ?-arrestin. In addition to its desensitizing function, ?-arrestins have recently been shown to simultaneously activate downstream signaling. We tested whether oxytocin stimulation promotes ?-arrestin-mediated OXTR desensitization in vivo and activates ?-arrestin-mediated mitogen-activated protein kinase (MAPK) growth signaling. Uterine muscle strips isolated from wild-type mice exhibited diminished uterine contractility following repeated exposure to oxytocin, whereas uterine muscle strips from ?-arrestin-1 and ?-arrestin-2 knockout mice showed no desensitization. Utilizing siRNA knockdown of ?-arrestin-1 and ?-arrestin-2 in HEK-293 cells expressing the OXTR, we demonstrated oxytocin-mediated MAPK signaling that was dependent on ?-arrestin-1 and ?-arrestin-2. Wild-type and ?-arrestin-1 and ?-arrestin-2 knockout mice receiving intravenous oxytocin also demonstrated oxytocin-mediated MAPK signaling that was dependent on ?-arrestin-1 and ?-arrestin-2. Finally, to test the significance of ?-arrestin-mediated signaling from the OXTR, HEK-293 cells expressing the OXTR showed ?-arrestin-dependent proliferation in a cell migration assay following oxytocin treatment. In conclusion, ?-arrestin is a multifunctional scaffold protein that mediates both desensitization of the OXTR, leading to decreases in uterine contractility, and MAPK growth signaling following stimulation by oxytocin. The development of unique OXTR ligands that prevent receptor desensitization may be a novel approach in the treatment of adverse clinical events secondary to prolonged oxytocin therapy.
Project description:Uterine contraction, crucial for successful labor, has been proved to be enchanced by hypoxia, which underlying mechanisms are yet to be elucidated. We found blockade of HIF-1a caused contractility decrease in myometrium and myocytes in hypoxic models. ChIP-seq revealed that HIF-1α directly bound to gemone of 2 typical contraction-associated proteins, the promoter of GJA1 and intron of OXTR. Blockade of GJA1 led to significant decrease of myometrial contractions under hypoxic tissue model, whereas atosiban did not influence the contractility. The conducted research suggests that HIF-1α is required for the augmentation of myometrial contractility via regulating GJA1 under hypoxia.
Project description:Actomyosin contractility regulates cell morphology and movement. The objective of this study was to identify whether actomyosin contractility regulates gene expression in tumour cells and whether such genes are involved in cell morphology and movement. Gene expression analysis was carried out on highly contractile melanoma cell line A375M2 plated on a deformable collagen matrix under conditions where actomyosin contractility could be altered following treatment with blebbistatin, a direct inhibitor of myosin II, or Rho-kinase inhibitors Y27632 or H1152 that interfere with signalling to myosin II. 18 samples (6 x 3 biological replicates). Cells were plated on rigid or deformable matrices. Rounded cells (A375M2 melanoma cells) plated on deformable matrices were left untreated or treated with Rho-kinase inhibitors Y27632, H1152 or blebbistatin an inhibitor of mysoin II.