Loss of receptor activity-modifying protein 2 in mice causes placental dysfunction and alters PTH1R regulation

Receptor activity-modifying protein 2 (Ramp2) is a single-pass transmembrane protein that heterodimerizes with several family B G-protein coupled receptors to alter their function. Ramp2 has been primarily characterized in association with calcitonin receptor-like receptor (Calcrl, CLR), forming the canonical receptor complex for the endocrine peptide adrenomedullin (Adm, AM). However, we previously demonstrated that Ramp2+/- female mice display a constellation of endocrine-related phenotypes that are distinct from those of Adm+/- and Calcrl+/- mice, implying that RAMP2 has physiological functions beyond its canonical complex. Here, we localize Ramp2 expression in the mouse placenta, finding that Ramp2 is robustly expressed in the fetal labyrinth layer, and then characterize the effects of loss of Ramp2 on placental development. Consistent with the expression pattern of Ramp2 in the placenta, Ramp2-/- placentas have a thinner labyrinth layer with significantly fewer trophoblast cells secondary to a reduction in trophoblast proliferation. We also find that absence of Ramp2 leads to failed spiral artery remodeling unaccompanied by changes in the uterine natural killer cell population. Furthermore, we assess changes in gene expression of other RAMP2-associated G-protein coupled receptors (GPCRs), concluding that Ramp2 loss decreases parathyroid hormone 1 receptor (Pthr1) expression and causes a blunted response to systemic parathyroid hormone (PTH) administration in mice. Ultimately, these studies provide in vivo evidence of a role for RAMP2 in placental development distinct from the RAMP2-CLR/AM signaling paradigm and identify additional pathways underlying the endocrine and fertility defects of the previously characterized Ramp2 heterozygous adult females

Orphan Gpr182 suppresses ERK-mediated intestinal proliferation during regeneration and adenoma formation

Orphan GPCRs provide an opportunity to identify potential pharmacological targets, yet their expression patterns and physiological functions remain challenging to elucidate. Here, we have used a genetically engineered knockin reporter mouse to map the expression pattern of the Gpr182 during development and adulthood. We observed that Gpr182 is expressed at the crypt base throughout the small intestine, where it is enriched in crypt base columnar stem cells, one of the most active stem cell populations in the body. Gpr182 knockdown had no effect on homeostatic intestinal proliferation in vivo, but led to marked increases in proliferation during intestinal regeneration following irradiation-induced injury. In the ApcMin mouse model, which forms spontaneous intestinal adenomas, reductions in Gpr182 led to more adenomas and decreased survival. Loss of Gpr182 enhanced organoid growth efficiency ex vivo in an EGF-dependent manner. Gpr182 reduction led to increased activation of ERK1/2 in basal and challenge models, demonstrating a potential role for this orphan GPCR in regulating the proliferative capacity of the intestine. Importantly, GPR182 expression was profoundly reduced in numerous human carcinomas, including colon adenocarcinoma. Together, these results implicate Gpr182 as a negative regulator of intestinal MAPK signaling–induced proliferation, particularly during regeneration and adenoma formation

Взаимосвязь понятий «стиль» и «имидж» как эстетическая проблема

<div><p>The intestinal microbiota influences the development and function of myeloid lineages such as neutrophils, but the underlying molecular mechanisms are unresolved. Using gnotobiotic zebrafish, we identified the immune effector Serum amyloid A (Saa) as one of the most highly induced transcripts in digestive tissues following microbiota colonization. Saa is a conserved secreted protein produced in the intestine and liver with described effects on neutrophils <i>in vitro</i>, however its <i>in vivo</i> functions remain poorly defined. We engineered <i>saa</i> mutant zebrafish to test requirements for Saa on innate immunity <i>in vivo</i>. Zebrafish mutant for <i>saa</i> displayed impaired neutrophil responses to wounding but augmented clearance of pathogenic bacteria. At baseline, <i>saa</i> mutants exhibited moderate neutrophilia and altered neutrophil tissue distribution. Molecular and functional analyses of isolated neutrophils revealed that Saa suppresses expression of pro-inflammatory markers and bactericidal activity. Saa’s effects on neutrophils depended on microbiota colonization, suggesting this protein mediates the microbiota’s effects on host innate immunity. To test tissue-specific roles of Saa on neutrophil function, we over-expressed <i>saa</i> in the intestine or liver and found that sufficient to partially complement neutrophil phenotypes observed in <i>saa</i> mutants. These results indicate Saa produced by the intestine in response to microbiota serves as a systemic signal to neutrophils to restrict aberrant activation, decreasing inflammatory tone and bacterial killing potential while simultaneously enhancing their ability to migrate to wounds.</p></div

Decoy Receptor CXCR7 Modulates Adrenomedullin-Mediated Cardiac and Lymphatic Vascular Development

Atypical 7-transmembrane receptors, often called decoy receptors, act promiscuously as molecular sinks to regulate ligand bioavailability and consequently temper the signaling of canonical G protein-coupled receptor (GPCR) pathways. Loss of mammalian CXCR7, the most recently described decoy receptor, results in postnatal lethality due to aberrant cardiac development and myocyte hyperplasia. Here, we provide the molecular underpinning for this proliferative phenotype by demonstrating that the dosage and signaling of adrenomedullin (Adm = gene, AM = protein)—a mitogenic peptide-hormone required for normal cardiovascular development—is tightly controlled by CXCR7. To this end, Cxcr7−/− mice exhibit gain-of-function cardiac and lymphatic vascular phenotypes which can be reversed upon genetic depletion of adrenomedullin ligand. In addition to identifying a biological ligand accountable for the phenotypes of Cxcr7−/− mice, these results reveal a previously underappreciated role for decoy receptors as molecular rheostats in controlling the timing and extent of GPCR-mediated cardiac and vascular development

Fetal-derived adrenomedullin mediates the innate immune milieu of the placenta

The remodeling of maternal uterine spiral arteries (SAs) is an essential process for ensuring low-resistance, high-capacitance blood flow to the growing fetus. Failure of SAs to remodel is causally associated with preeclampsia, a common and life-threatening complication of pregnancy that is harmful to both mother and fetus. Here, using both loss-of-function and gain-of-function genetic mouse models, we show that expression of the pregnancy-related peptide adrenomedullin (AM) by fetal trophoblast cells is necessary and sufficient to promote appropriate recruitment and activation of maternal uterine NK (uNK) cells to the placenta and ultimately facilitate remodeling of maternal SAs. Placentas that lacked either AM or its receptor exhibited reduced fetal vessel branching in the labyrinth, failed SA remodeling and reendothelialization, and markedly reduced numbers of maternal uNK cells. In contrast, overexpression of AM caused a reversal of these phenotypes with a concomitant increase in uNK cell content in vivo. Moreover, AM dose-dependently stimulated the secretion of numerous chemokines, cytokines, and MMPs from uNK cells, which in turn induced VSMC apoptosis. These data identify an essential function for fetal-derived factors in the maternal vascular adaptation to pregnancy and underscore the importance of exploring AM as a biomarker and therapeutic agent for preeclampsia

Loss of receptor activity-modifying protein 2 in mice causes placental dysfunction and alters PTH1R regulation.

Receptor activity-modifying protein 2 (Ramp2) is a single-pass transmembrane protein that heterodimerizes with several family B G-protein coupled receptors to alter their function. Ramp2 has been primarily characterized in association with calcitonin receptor-like receptor (Calcrl, CLR), forming the canonical receptor complex for the endocrine peptide adrenomedullin (Adm, AM). However, we previously demonstrated that Ramp2+/- female mice display a constellation of endocrine-related phenotypes that are distinct from those of Adm+/- and Calcrl+/- mice, implying that RAMP2 has physiological functions beyond its canonical complex. Here, we localize Ramp2 expression in the mouse placenta, finding that Ramp2 is robustly expressed in the fetal labyrinth layer, and then characterize the effects of loss of Ramp2 on placental development. Consistent with the expression pattern of Ramp2 in the placenta, Ramp2-/- placentas have a thinner labyrinth layer with significantly fewer trophoblast cells secondary to a reduction in trophoblast proliferation. We also find that absence of Ramp2 leads to failed spiral artery remodeling unaccompanied by changes in the uterine natural killer cell population. Furthermore, we assess changes in gene expression of other RAMP2-associated G-protein coupled receptors (GPCRs), concluding that Ramp2 loss decreases parathyroid hormone 1 receptor (Pthr1) expression and causes a blunted response to systemic parathyroid hormone (PTH) administration in mice. Ultimately, these studies provide in vivo evidence of a role for RAMP2 in placental development distinct from the RAMP2-CLR/AM signaling paradigm and identify additional pathways underlying the endocrine and fertility defects of the previously characterized Ramp2 heterozygous adult females

Loss of <i>Ramp2</i> alters mRNA expression of RAMP2-associating GPCRs, including <i>Pthr1</i>.

<p>(A) mRNA expression of RAMP2-interacting GPCRs from e13.5 wild type and <i>Ramp2</i>^<i>-/-</i> placentas (n≥3 placentas per genotype). (B) PTH1R protein expression by immunoblot of e13.5 tissue lysates from wild type and <i>Ramp2</i>^<i>-/-</i> placentas. (C and D), Immunofluorescence for PTH1R in the labyrinth of wild type and <i>Ramp2</i>^<i>-/-</i> placentas. Scale bars, 100 μm. <i>Pth1r</i>, parathyroid hormone receptor 1; <i>Casr</i>, calcium-sensing receptor; <i>Ctr</i>, calcitonin receptor; <i>Calcrl</i>, calcitonin receptor-like receptor; <i>Gcgr</i>, glucagon receptor; <i>Vpac1r</i>, vasoactive intestinal peptide receptor 1; <i>Crhr1</i>, corticotrophin releasing hormone receptor 1. *p<0.01.</p

Loss of <i>Ramp2</i> leads to a proliferation defect in the labyrinth layer.

<p>(A and B) Immunofluorescence for BrdU in e13.5 placentas. Scale bars, 500<b>μ</b>m. (C and D) Immunofluorescence for Ki67 in the labyrinth of e13.5 placentas. Scale bars, 500 μm. (E) Ratio of <i>Bax</i> to <i>Bcl2</i> mRNA expression normalized to <i>Gapdh</i> as measured by qRT-PCR (n≥5 placentas per genotype). lb, labyrinth; jz, junctional zone; dec, decidua.</p

<i>Ramp2</i> is essential for proper development of the labyrinth layer of the placenta.

<p>(A and B), Hematoxylin and eosin staining of e13.5 wild type and <i>Ramp2</i>^<i>-/-</i> littermate placentas. Horizontal and vertical lines are representative of axes measured in panels (C) and (D) Scale bars, 1 mm. (C and D), Quantification of width and thickness of wild type and <i>Ramp2-/-</i> labyrinth layers (n≥6 placentas per genotype). (E and F), Immunofluorescence for cytokeratin in wild type and <i>Ramp2</i>^<i>-/-</i> placentas, showing trophoblast cells in the fetal compartment of the placenta. Scale bar, 500<b>μ</b>m. (G) Quantitation of labyrinth trophoblast cells, identified by histology (n = 3 fields per animal, n≥3 placentas per genotype). (H and I) Representative images of wild type and <i>Ramp2</i>^<i>-/-</i> placentas with pseudocolored maternal (yellow) and fetal (blue) sinuses. (J) Comparison of the total area of the non-vascular region and of the maternal sinuses in wild type and <i>Ramp2</i>^<i>-/-</i> placentas (n≥2 fields per placenta from multiple placentas per genotype). cp, chorionic plate; lb, labyrinth; jz, junctional zone; dec, dedicua; myo, myometrium. *p<0.05, **p<0.01, ***p<0.001</p