Explore the vast range of titles available.

Throughout most of pregnancy, uterine quiescence is maintained by increased progesterone receptor (PR) transcriptional activity, whereas spontaneous labor is initiated/facilitated by a concerted series of biochemical events that activate inflammatory pathways and have a negative impact on PR function. In this study, we uncovered a previously undescribed regulatory pathway whereby micro-RNAs (miRNAs) serve as hormonally modulated and conserved mediators of contraction-associated genes in the pregnant uterus in the mouse and 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 down-regulated targets, zinc finger E-box binding homeobox proteins ZEB1 and ZEB2, which act as transcriptional repressors. We also observed up-regulation of the miR-200 family and down-regulation of ZEB1 and ZEB2 in two different mouse models of preterm labor. We further demonstrated that ZEB1 is directly up-regulated by the action of progesterone (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 unique P₄/PR-mediated regulators of uterine quiescence and contractility during pregnancy and labor and shed light on the molecular mechanisms involved in preterm birth.

TRPM6 and TRPM7 are members of the melastatin-related transient receptor potential (TRPM) subfamily of ion channels. Deletion of either gene in mice is embryonically lethal. TRPM6/7 are the only known examples of single polypeptides containing both an ion channel pore and a serine/threonine kinase (chanzyme). Here we show that the C-terminal kinase domain of TRPM6 is cleaved from the channel domain in a cell type-specific fashion and is active. Cleavage requires that the channel conductance is functional. The cleaved kinase translocates to the nucleus, where it is strictly localized and phosphorylates specific histone serine and threonine (S/T) residues. TRPM6-cleaved kinases (M6CKs) bind subunits of the protein arginine methyltransferase 5 (PRMT5) molecular complex that make important epigenetic modifications by methylating histone arginine residues. Histone phosphorylation by M6CK results in a dramatic decrease in methylation of arginines adjacent to M6CK-phosphorylated amino acids. Knockout of TRPM6 or inactivation of its kinase results in global changes in histone S/T phosphorylation and changes the transcription of hundreds of genes. We hypothesize that M6CK associates with the PRMT5 molecular complex in the nucleus, directing M6CK to a specific genomic location and providing site-specific histone phosphorylation. M6CK histone phosphorylation, in turn, regulates transcription by attenuating the effect of local arginine methylation.

During pregnancy, uterine quiescence is maintained by increased progesterone receptor (PR) activity, but labor is facilitated by a series of events that impair PR function. Previously, we discovered that miR-200 family members serve as progesterone (P4)-modulated activators of contraction-associated genes in the pregnant uterus. In this study, we identified a unique role for miR-200a to enhance the local metabolism of P4 in myometrium and, thus, decrease PR function during the progression toward labor. miR-200a exerts this action by direct repression of STAT5b, a transcriptional repressor of the P4-metabolizing enzyme 20α-hydroxysteroid dehydrogenase (20α-HSD). We observed that miR-200a expression increased and STAT5b expression coordinately decreased in myometrium of mice as they progressed to labor and in laboring myometrium from pregnant women. These changes were associated with a dramatic increase in expression and activity of 20α-HSD in laboring myometrium from mouse and human. Notably, overexpression of miR-200a in cultured human myometrial cells (hTERT-HM) suppressed STAT5b and increased 20α-HSD mRNA levels. In uterine tissues of ovariectomized mice injected with P4, miR-200 expression was significantly decreased, STAT5b expression was up-regulated, and 20α-HSD mRNA was decreased, but in 15 d postcoitum pregnant mice injected with the PR antagonist RU486, preterm labor was associated with increased miR-200a, decreased STAT5b, and enhanced 20α-HSD expression. Taken together, these findings implicate miR-200a as an important regulator of increased local P4 metabolism in the pregnant uterus near term and provide insight into the importance of miR-200s in the decline in PR function leading to labor.

Chronic morphine administration (via subcutaneous pellet) decreases the size of dopamine neurons in the ventral tegmental area (VTA), a key reward region in the brain, yet the molecular basis and functional consequences of this effect are unknown. In this study, we used viral-mediated gene transfer in rat to show that chronic morphine–induced downregulation of the insulin receptor substrate 2 (IRS2)–thymoma viral proto-oncogene (Akt) signaling pathway in the VTA mediates the decrease in dopamine cell size seen after morphine exposure and that this downregulation diminishes morphine reward, as measured by conditioned place preference. We further show that the reduction in size of VTA dopamine neurons persists up to 2 weeks after morphine withdrawal, which parallels the tolerance to morphine's rewarding effects caused by previous chronic morphine exposure. These findings directly implicate the IRS2-Akt signaling pathway as a critical regulator of dopamine cell morphology and opiate reward.

The precise mechanisms that lead to parturition are incompletely defined. Surfactant protein-A (SP-A), which is secreted by fetal lungs into amniotic fluid (AF) near term, likely provides a signal for parturition; however, SP-A-deficient mice have only a relatively modest delay (~12 hours) in parturition, suggesting additional factors. Here, we evaluated the contribution of steroid receptor coactivators 1 and 2 (SRC-1 and SRC-2), which upregulate SP-A transcription, to the parturition process. As mice lacking both SRC-1 and SRC-2 die at birth due to respiratory distress, we crossed double-heterozygous males and females. Parturition was severely delayed (~38 hours) in heterozygous dams harboring SRC-1/-2-deficient embryos. These mothers exhibited decreased myometrial NF-κB activation, PGF2α, and expression of contraction-associated genes; impaired luteolysis; and elevated circulating progesterone. These manifestations also occurred in WT females bearing SRC-1/-2 double-deficient embryos, indicating that a fetal-specific defect delayed labor. SP-A, as well as the enzyme lysophosphatidylcholine acyltransferase-1 (LPCAT1), required for synthesis of surfactant dipalmitoylphosphatidylcholine, and the proinflammatory glycerophospholipid platelet-activating factor (PAF) were markedly reduced in SRC-1/-2-deficient fetal lungs near term. Injection of PAF or SP-A into AF at 17.5 days post coitum enhanced uterine NF-κB activation and contractile gene expression, promoted luteolysis, and rescued delayed parturition in SRC-1/-2-deficient embryo-bearing dams. These findings reveal that fetal lungs produce signals to initiate labor when mature and that SRC-1/-2-dependent production of SP-A and PAF is crucial for this process.

This Review highlights the key role of microRNAs and their targets in the maintenance of pregnancy and initiation of term and preterm labour. The authors review data on microRNAs as evolutionarily conserved, hormonally controlled modulators of inflammatory and contractile gene expression in the uterus during pregnancy. The maintenance of myometrial quiescence and initiation of contractility, which lead to parturition at term and preterm, involve a shifting equilibrium between anti-inflammatory and proinflammatory signalling pathways. Progesterone (P 4 ), acting through the progesterone receptor (PR), has an essential and multifaceted role in the maintenance of myometrial quiescence. This effect of P 4 –PR signalling is mediated, in part, by its anti-inflammatory actions and capacity to repress the expression of genes that encode proinflammatory cytokines, such as IL-1 and IL-6, and contraction-associated proteins, such as OXTR , GJA1 and PTGS2 . By contrast, increased expression of genes that ultimately lead to parturition is mediated by enhanced inflammatory and estradiol-17β (E 2 ) and estrogen receptor α signalling, which reduce PR function, thus further intensifying the inflammatory response. To obtain a more complete understanding of the molecular events that underlie the transition of the pregnant myometrium from a refractory to a contractile state, the roles of microRNAs, their targets, and their transcriptional and hormonal regulation have been investigated. This article reviews the actions of the miR-200 family and their P 4 -regulated targets—the transcription factors ZEB1, ZEB2 and STAT5B—in the pregnant myometrium, as well as the role of miR-199a-3p and miR-214 and their mutual target PTGS2. The central role of ZEB1 as the mediator of the opposing actions of P 4 and E 2 on myometrial contractility will be highlighted. Key Points Progesterone (P 4 ), acting via the progesterone receptor (PR), maintains uterine quiescence in part by increasing the expression of ZEB1 and ZEB2 , which inhibit the contraction-associated genes OXTR and GJA1 The initiation of myometrial contractility is mediated by an increased inflammatory response, an associated increase in 17β-estradiol (E 2 ) and estrogen receptor (ERα) signalling and a decline in PR function Near term, the myometrial inflammatory response is promoted by physical and hormonal signals from mother and fetus; in preterm labour, the increased inflammatory response is commonly induced by a bacterial infection Expression of the miR-200 family increases in mouse and human myometrium near term and suppresses ZEB1 and ZEB2 levels, which results in the de-repression of contractile genes and increased myometrial contractility Increased miR-200 expression near term also inhibits STAT5B; decreased STAT5B levels de-repress 20α-hydroxysteroid dehydrogenase and increase myometrial metabolism of P 4 Increased E 2 –ERα signalling and the decline in PR function near term mediate decreased expression of ZEB1, and of miR-199a-3p and miR-214, which contributes to the induction of PTGS2

Although the human nonclassical class Ib major histocompatibility complex (Mhc) locus, HLA-G, is known to act as an immune suppressor in immune-privileged sites, little is currently known regarding participation of the rodent class Ib Mhc in similar pathways. Here, we investigated the expression properties of the mouse nonclassical Mhc H2-Q5 k gene, previously detected in tumors and tissues associated with pregnancy. We find that H2-Q5 k is alternatively spliced into multiple novel isoforms in a wide panel of C3H tissues. Unlike other known class I MHC, it is most highly transcribed in the brain, where the classical class Ia Mhc products are scarce. The truncated isoforms are selectively enriched in sites of immune privilege and are translated into cell surface proteins in neural crest-derived transfected cells. Furthermore, we present data supporting a model whereby Q5k isoforms serve an immune-protective role by donating their Qdm leader peptide to Qa-1, in a pathway homologous to the HLA-G leader fragment binding HLA-E and inhibiting CD94/NKG2A-positive cytotoxic cells. In addition, we report a previously unknown homolog of H2-Q5 k in the C57BL/6 mouse, which encodes Qdm, but is transcribed solely into noncanonical isoforms. Collectively, these studies demonstrate that H2-Q5 k , and its homologous class I-like H2 b gene may play tissue-specific roles in regulating immune surveillance.

As pediatric populations in the United States (US) become increasingly diverse, current practices for interpreting bone density using DXA in children warrant reevaluation. The International Society for Clinical Densitometry currently recommends adjusting pediatric bone density Z-scores by race, sex, and age. However, race-based adjustments risk reinforcing disparities and perpetuating systemic inequities in pediatric bone health assessment. We conducted a scoping review of studies examining racial and ethnic differences in BMD among healthy US children, identifying 3960 records across 4 databases, of which 54 met inclusion criteria. Across these studies, reporting of race and ethnicity was inconsistent: although nearly all relied on self- or parent-report, none provided explicit definitions, and only 13% confirmed concordance across grandparents. Fifty percent of studies reported statistically significant racial differences in BMD, yet most did so without comprehensive covariate adjustment. By contrast, studies that accounted for height, lean mass, and pubertal status frequently found that differences attenuated or disappeared. These findings underscore the need to critically reconsider race-based adjustments in pediatric DXA interpretation. Developing and validating race-neutral reference standards, with attention to structural determinants and biologically relevant measures, such as stature, body composition, and pubertal timing, is essential for achieving a more equitable and clinically meaningful assessment of pediatric bone health.

Abstract Adrenal suppression is an iatrogenic form of adrenal insufficiency that occurs secondary to exogenous glucocorticoids (GCs) and is a documented cause of premature mortality among individuals with Duchenne muscular dystrophy (DMD). Adrenal suppression in DMD necessitates awareness and careful management, given that GCs are currently the mainstay of therapy for individuals living with DMD. Vamorolone, a novel GC that has recently been approved in some regions worldwide for the treatment of DMD, has also been reported to place individuals at high risk of adrenal suppression in a dose-dependent fashion, requiring health care professional awareness. Vamorolone is a mineralocorticoid receptor antagonist, which differentiates it from classic GCs, and this characteristic impacts the approach to adrenal suppression management. This contemporary perspective provides insights into the mechanisms underlying adrenal suppression due to both classic GCs and novel vamorolone therapy, followed by an overview of adrenal suppression management with a particular focus on the unique aspects of providing care for individuals treated with vamorolone. It also emphasizes the importance of educating the DMD community and health care providers about the recognition and management of adrenal suppression and outlines critical concepts for clinicians managing adrenal suppression risk, tapering GCs, and transitioning from classic GC therapy to vamorolone. The key principles of managing adrenal suppression due to classic GCs and novel vamorolone therapy highlighted in this perspective are expected to enhance clinical practice, mitigate mortality, and optimize health outcomes for individuals with DMD.

Abstract Disclosure: J. Baronas: None. U. Ahmed: None. J.N. Hirschhorn: None. N.E. Renthal: None. Development of growth plate chondrocytes is a complex process that involves a wide array of regulatory elements. Recently our laboratory conducted a genome wide CRISPR knockout (KO) screen of growth plate chondrocyte maturation to discover novel genes and gene networks in the proliferation and maturation of chondrocytes. Among targets uncovered is Protein Inhibitor of Activated STAT 1 (Pias1), an E3 SUMO ligase that plays a multi-faceted role in genetic regulation, driving post-translational modifications, directly binding to transcription factors, and functioning as a DNA-binding protein. While Pias1 has been shown to be involved in the regulation of many cellular processes across multiple tissues, its function in growth plate development and chondrocyte maturation has been previously unstudied. In our genome-wide screen, our laboratory identified that loss of Pias1 led to early maturation of chondrocytes. This project seeks to investigate the role of Pias1 in chondrocyte maturation and differentiation. We first developed a Pias1-KO chondrocyte cell line, observing upregulation of hypertrophic markers Cd200 and Col10a1 in KOs relative to control via qPCR, in addition to proliferative regulators IHH and Pth1R. Through Bulk-RNAseq of the same cell line, we identified additional chondrocyte markers as upregulated in KO, as well as osteoblast marker Sp7. Members of the HoxD family, regulators of limb development, were downregulated. Cell culture data suggests that loss of Pias1 leads to increased cell proliferation and increased matrix production, indicating dysregulation of multiple chondrocyte processes. Immunohistochemistry of micromass culture sections also suggests morphological differences between KO and control, with KO cells significantly larger in diameter. Early SUMO-1 profiling yields limited evidence of decreased global SUMOylation in KO cells, one possible mechanistic explanation for the observed dysregulation. Ongoing studies are focused on identifying specific SUMOylation targets of Pias1 in chondrocytes, analyzing proteomic differences in KO and control, seeking putative DNA-binding sites of Pias1, and observing in vivo murine Pias1-KO growth plates. Our findings suggest that PIAS1 plays a crucial role in the growth plate by prolonging growth and delaying terminal hypertrophy. Our study aims to provide a better understanding of the regulatory pathways involved in growth plate development and related phenotypes such as height, and contribute to the development of novel therapies for growth-related disorders, such as achondroplasia and hypochondroplasia. Presentation: 6/1/2024