RESUMO
Calcitonin gene-related peptide (CGRP) and adrenomedullin 2/intermedin (AM2/IMD) play important roles in several pathologies, including cardiovascular disease, migraine and cancer. The efficacy of drugs targeting CGRP signalling axis for the treatment of migraine patients is sometimes offset by side effects (e.g. inflammation and microvascular complications, including aberrant neovascularisation in the skin). Recent studies using animal models implicate CGRP in lymphangiogenesis and lymphatic vessel function. However, whether CGRP or AM2/IMD can act directly on lymphatic endothelial cells is unknown. Here, we found that CGRP and AM2/IMD induced p44/42 MAPK phosphorylation in a time- and dose-dependent manner in primary human dermal lymphatic endothelial cells (HDLEC) in vitro, and thus directly affected these cells. These new findings reveal CGRP and AM2/IMD as novel regulators of LEC biology and warrant further investigation of their roles in the context of pathologies associated with lymphatic function in the skin and other organs, and therapies targeting CGRP signalling axis.
Assuntos
Adrenomedulina , Peptídeo Relacionado com Gene de Calcitonina , Células Endoteliais , Proteína Quinase 1 Ativada por Mitógeno , Proteína Quinase 3 Ativada por Mitógeno , Humanos , Adrenomedulina/metabolismo , Adrenomedulina/farmacologia , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Células Cultivadas , Células Endoteliais/metabolismo , Células Endoteliais/efeitos dos fármacos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Hormônios Peptídicos , Fosforilação/efeitos dos fármacosRESUMO
The G protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) mediates essential functions in several cell types and is implicated in cardiovascular pathologies, skin diseases, migraine, and cancer. To date, the network of proteins interacting with CLR ("CLR interactome") in primary cells, where this GPCR is expressed at endogenous (physiologically relevant) levels, remains unknown. To address this knowledge gap, we established a novel integrative methodological workflow/approach for conducting a comprehensive/proteome-wide analysis of Homo sapiens CLR interactome. We used primary human dermal lymphatic endothelial cells and combined immunoprecipitation utilizing anti-human CLR antibody with label-free quantitative nano LC-MS/MS and quantitative in situ proximity ligation assay. By using this workflow, we identified 37 proteins interacting with endogenously expressed CLR amongst 4902 detected members of the cellular proteome (by quantitative nano LC-MS/MS) and revealed direct interactions of two kinases and two transporters with this GPCR (by in situ proximity ligation assay). All identified interactors have not been previously reported as members of CLR interactome. Our approach and findings uncover the hitherto unrecognized compositional complexity of the interactome of endogenously expressed CLR and contribute to fundamental understanding of the biology of this GPCR. Collectively, our study provides a first-of-its-kind integrative methodological approach and datasets as valuable resources and robust platform/springboard for advancing the discovery and comprehensive characterization of physiologically relevant CLR interactome at a proteome-wide level in a range of cell types and diseases in future studies.
Assuntos
Proteína Semelhante a Receptor de Calcitonina , Proteômica , Humanos , Proteômica/métodos , Proteína Semelhante a Receptor de Calcitonina/metabolismo , Proteína Semelhante a Receptor de Calcitonina/genética , Espectrometria de Massas em Tandem/métodos , Proteoma/metabolismo , Proteoma/análise , Células Endoteliais/metabolismo , Cromatografia Líquida/métodosRESUMO
The bidirectional association between coagulation and cancer has been established. However, anticoagulant therapies have been reported to have beneficial outcomes by influencing the vascularisation of the tumours. In this study the influence of a set of anticoagulants on tumour formation, invasion and vascularisation was examined. WM-266-4 melanoma and AsPC-1 pancreatic cancer cell lines were treated with LMWH (Tinzaparin and Dalteparin), and DOAC (Apixaban and Rivaroxaban) and the rate of tumour formation, growth and invasion were measured in vitro. In addition, the influence of these anticoagulants on vascularisation was examined using the chorioallantoic membrane assay (CAM) model and compared to the outcome of treatment with Bevacizumab. Using this model the influence of pharmacological concentrations of the anticoagulant on the growth, invasion and vascularisation of tumours derived from WM-266-4 and AsPC-1 cells was also measured in vivo. Tinzaparin and Daltepain reduced tumour formation and invasion by the cell lines in vitro, but with dissimilar potencies. In addition, treatment of CAM with LMWH reduced the local vascular density beyond that achievable with Bevacizumab, particularly suppressing the formation of larger-diameter blood vessels. In contrast, treatment with DOAC was largely ineffective. Treatment of CAM-implanted tumours with LMWH also reduced tumour vascularisation, while treatment of tumours with Apixaban reduced tumour growth in vivo. In conclusion, LMWH and DOAC appear to have anti-cancer properties that are exerted through different mechanisms.
Assuntos
Coagulação Sanguínea/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Heparina de Baixo Peso Molecular/farmacologia , Neovascularização Patológica/tratamento farmacológico , Anticoagulantes/farmacologia , Testes de Coagulação Sanguínea , Linhagem Celular Tumoral , Inibidores do Fator Xa/farmacologia , Humanos , Melanoma/tratamento farmacológico , Melanoma/metabolismo , Melanoma/patologia , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Neovascularização Patológica/metabolismo , Neovascularização Patológica/patologia , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologiaRESUMO
Angiogenesis, the fundamental process by which new blood vessels form from existing ones, depends on precise spatial and temporal gene expression within specific compartments of the endothelium. However, the molecular links between proangiogenic signals and downstream gene expression remain unclear. During sprouting angiogenesis, the specification of endothelial cells into the tip cells that lead new blood vessel sprouts is coordinated by vascular endothelial growth factor A (VEGFA) and Delta-like ligand 4 (Dll4)/Notch signaling and requires high levels of Notch ligand DLL4. Here, we identify MEF2 transcription factors as crucial regulators of sprouting angiogenesis directly downstream from VEGFA. Through the characterization of a Dll4 enhancer directing expression to endothelial cells at the angiogenic front, we found that MEF2 factors directly transcriptionally activate the expression of Dll4 and many other key genes up-regulated during sprouting angiogenesis in both physiological and tumor vascularization. Unlike ETS-mediated regulation, MEF2-binding motifs are not ubiquitous to all endothelial gene enhancers and promoters but are instead overrepresented around genes associated with sprouting angiogenesis. MEF2 target gene activation is directly linked to VEGFA-induced release of repressive histone deacetylases and concurrent recruitment of the histone acetyltransferase EP300 to MEF2 target gene regulatory elements, thus establishing MEF2 factors as the transcriptional effectors of VEGFA signaling during angiogenesis.
Assuntos
Células Endoteliais/citologia , Células Endoteliais/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Fatores de Transcrição MEF2/metabolismo , Neovascularização Fisiológica/genética , Animais , Células Cultivadas , Embrião não Mamífero , Células Endoteliais/enzimologia , Elementos Facilitadores Genéticos/genética , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fatores de Transcrição MEF2/química , Fatores de Transcrição MEF2/genética , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Neovascularização Patológica/genética , Domínios e Motivos de Interação entre Proteínas , Retina/embriologia , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular/metabolismo , Peixe-ZebraRESUMO
PURPOSE: The G-protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) and its ligand peptide adrenomedullin (encoded by ADM gene) are implicated in tumor angiogenesis in mouse models but poorly defined in human cancers. We therefore investigated the diagnostic/prognostic use for CLR in human tumor types that may rely on adrenomedullin signaling and in clear cell renal cell carcinoma (RCC), a highly vascular tumor, in particular. EXPERIMENTAL DESIGN: In silico gene expression mRNA profiling microarray study (n = 168 tumors) and cancer profiling cDNA array hybridization (n = 241 pairs of patient-matched tumor/normal tissue samples) were carried out to analyze ADM mRNA expression in 13 tumor types. Immunohistochemistry on tissue microarrays containing patient-matched renal tumor/normal tissues (n = 87 pairs) was conducted to study CLR expression and its association with clinicopathologic parameters and disease outcome. RESULTS: ADM expression was significantly upregulated only in RCC and endometrial adenocarcinoma compared with normal tissue counterparts (P < 0.01). CLR was localized in tumor cells and vessels in RCC and upregulated as compared with patient-matched normal control kidney (P < 0.001). Higher CLR expression was found in advanced stages (P < 0.05), correlated with high tumor grade (P < 0.01) and conferred shorter overall survival (P < 0.01). CONCLUSIONS: In human tissues ADM expression is upregulated in cancer type-specific manner, implicating potential role for adrenomedullin signaling in particular in RCC, where CLR localization suggests autocrine/paracrine mode for adrenomedullin action within the tumor microenvironment. Our findings reveal previously unrecognized CLR upregulation in an autocrine loop with adrenomedullin in RCC with potential application for this GPCR as a target for future functional studies and drug development.
Assuntos
Adrenomedulina/metabolismo , Comunicação Autócrina , Proteína Semelhante a Receptor de Calcitonina/metabolismo , Carcinoma de Células Renais/metabolismo , Neoplasias Renais/metabolismo , Adrenomedulina/genética , Idoso , Comunicação Autócrina/genética , Proteína Semelhante a Receptor de Calcitonina/genética , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/mortalidade , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Feminino , Seguimentos , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Renais/genética , Neoplasias Renais/mortalidade , Neoplasias Renais/patologia , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Carga TumoralRESUMO
Secondary lymphedema is a debilitating condition, and genetic factors predisposing to its development remain largely unknown. Adrenomedullin (AM) is peptide encoded, together with proadrenomedullin N-terminal peptide (PAMP), by the Adm gene (adrenomedullin gene). AM and its putative receptor calcitonin receptor-like receptor (CLR) are implicated in angiogenesis and lymphangiogenesis during embryogenesis and wound healing, suggesting their possible involvement in secondary lymphedema. To investigate whether AM deficiency predisposes to secondary lymphedema, we used heterozygous adult mice with Adm gene-knockin stop mutation, which selectively abrogated AM, but preserved PAMP, expression (Adm(AM+/Δ) animals). After hind limb skin incision, Adm messenger RNA expression was upregulated in wounded tissue of both Adm(AM+/+) and Adm(AM+/Δ) mice. However, only Adm(AM+/Δ) animals developed limb swelling and histopathological lymphedematous changes, including epidermal thickening, elevated collagen fiber density, and increased microvessel diameter. Secondary lymphedema was prevented when circulating AM levels in Adm(AM+/Δ) mice were restored by systemic peptide delivery. In human skin, CLR was expressed in tissue components affected by lymphedema, including epidermis, lymphatics, and blood vessels. Our study identified a previously unrecognized role for endogenous AM as a key factor in secondary lymphedema pathogenesis and provided experimental in vivo evidence of an underlying germ-line genetic predisposition to developing this disorder.
Assuntos
Adrenomedulina/genética , Técnicas de Introdução de Genes , Predisposição Genética para Doença/genética , Haploinsuficiência/genética , Linfedema/genética , Mutação/genética , Animais , Proteína Semelhante a Receptor de Calcitonina/metabolismo , Células Cultivadas , Endotélio Linfático/metabolismo , Endotélio Vascular/metabolismo , Heterozigoto , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Fenótipo , Fatores de RiscoRESUMO
After menstruation, the endometrium has a remarkable capacity for repair, but the factors involved remain undefined. We hypothesize adrenomedullin (AM) plays a role in this process. Premenstrually progesterone levels decline, stimulating prostaglandin (PG) synthesis, vasoconstriction, and hypoxia. This study aimed to determine 1) AM expression throughout the menstrual (M) cycle and 2) its regulation by PG and hypoxia. Human endometrial biopsies (n = 51) were collected with ethical approval and consent. AM mRNA expression was examined by quantitative RT-PCR and was found to be selectively elevated in endometrium from the menstrual (M) phase (P < 0.001). AM immunohistochemical staining was maximal in M and proliferative (P) endometrium. Culture of secretory, but not P, explants with 100 nm PGF(2α) or hypoxia (0.5% O2) increased AM mRNA (P < 0.05). P explants were induced to increase AM expression using in vitro progesterone withdrawal but required the presence of hypoxia (P < 0.05). Short hairpin sequences against hypoxia-inducible factor-1α (HIF-1α) inhibited AM hypoxic up-regulation but did not alter PGF(2α)-induced expression. The AM receptor was immunolocalized to endothelial cells in both lymphatic and blood vessels. Conditioned medium from PGF(2α)-treated cells increased endothelial cell proliferation and branching (P < 0.05). This was abolished by AM receptor antagonists. In conclusion, AM is elevated at the time of endometrial repair and induces both angiogenesis and lymphangiogenesis by stimulating endothelial cell proliferation and tube formation. In the human endometrium, AM expression is up-regulated by two mechanisms: a HIF-1α-mediated hypoxic induction and a HIF-1α-independent PGF(2α) pathway. These physiological mechanisms may provide novel therapeutic targets for disorders such as heavy menstrual bleeding.
Assuntos
Adrenomedulina/metabolismo , Endométrio/fisiologia , Regulação da Expressão Gênica , Ciclo Menstrual/metabolismo , Adrenomedulina/genética , Adulto , Indutores da Angiogênese/metabolismo , Hipóxia Celular , Linhagem Celular , Proliferação de Células , Dinoprosta/metabolismo , Endométrio/irrigação sanguínea , Endométrio/citologia , Endotélio Vascular/fisiologia , Feminino , Inativação Gênica , Humanos , Fator 1 Induzível por Hipóxia/antagonistas & inibidores , Fator 1 Induzível por Hipóxia/genética , Linfangiogênese , Pessoa de Meia-Idade , Técnicas de Cultura de Órgãos , RNA Mensageiro/metabolismo , RNA Interferente Pequeno , Receptores de Adrenomedulina/antagonistas & inibidores , Receptores de Adrenomedulina/metabolismo , Receptores de Prostaglandina/metabolismoRESUMO
The vascular endothelium plays an essential role during organogenesis and in tissue homeostasis. Growing evidence also supports its essential and complex role in tumour biology and cancer progression. In particular, excessive proliferation and transformation or dysfunction of endothelial cells leads to pathological (lymph)angiogenesis or vascular malfunctions, which are hallmarks of neoplastic and malignant disorders. Reciprocal interactions between endothelial cells and the local tumour microenvironment may regulate tumour progression and resistance to anti-cancer therapies in a tumour-type-specific manner.
Assuntos
Endotélio Vascular/metabolismo , Neoplasias/metabolismo , Neovascularização Patológica/metabolismo , Animais , Resistencia a Medicamentos Antineoplásicos , Endotélio Vascular/patologia , Homeostase , Humanos , Neoplasias/patologia , Neoplasias/terapia , Neovascularização Patológica/patologia , Neovascularização Patológica/terapia , OrganogêneseRESUMO
Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma-associated herpesvirus (KSHV) and consists of proliferating spindle cells, which are related to lymphatic endothelial cells (LEC). Angiopoietin-2 (Ang2) is a secreted proangiogenic and lymphangiogenic molecule. Here, we show the expression of Ang2 protein in KS and confirm that KSHV infection up-regulates Ang2 in LEC. We show that a paracrine mechanism contributes to this up-regulation. A lentiviral library of individual KSHV-encoding genes, comprising the majority of known latent genes and a selection of lytic viral genes, was constructed to investigate the underlying mechanism of this up-regulation. Two lytic genes, viral interleukin-6 (vIL6) and viral G-protein-coupled receptor (vGPCR), up-regulated Ang2 expression in LEC. Both vIL6 and vGPCR are expressed in KSHV-infected LEC and caused up-regulation of Ang2 in a paracrine manner. KSHV, vIL6, and vGPCR up-regulated Ang2 through the mitogen-activated protein kinase (MAPK) pathway. Gene expression microarray analysis identified several other angiogenic molecules affected by KSHV, including the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis, which is also affected by vIL6 and vGPCR in LEC, and matrix metalloproteinases, which could act in concert with Ang2 to contribute to KS development. These findings support the paracrine and autocrine roles of the lytic KSHV-encoded proteins, vIL6 and vGPCR, in KS pathogenesis and identify Ang2 as a potential therapeutic target for this neoplasm.
Assuntos
Angiopoietina-2/biossíntese , Herpesvirus Humano 8/genética , Interleucina-6/genética , Receptores Acoplados a Proteínas G/genética , Sarcoma de Kaposi/virologia , Angiopoietina-2/genética , Células Endoteliais/metabolismo , Células Endoteliais/virologia , Regulação Neoplásica da Expressão Gênica , Biblioteca Gênica , Humanos , Interleucina-6/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neovascularização Patológica/genética , Neovascularização Patológica/metabolismo , Neovascularização Patológica/virologia , Receptores Acoplados a Proteínas G/metabolismo , Sarcoma de Kaposi/irrigação sanguínea , Sarcoma de Kaposi/genética , Sarcoma de Kaposi/metabolismo , Regulação para CimaRESUMO
PURPOSE: The role for the hypoxia-inducible angiogenic factor adrenomedullin (AM) in tumor growth and progression has been suggested. Calcitonin receptor-like receptor (CL) is a G protein-coupled receptor (GPCR) that mediates effects of AM, but little information is available on its expression and functional state in human tumors. The present study attempted to determine CL potential for antiangiogenic therapy of uterine leiomyoma. EXPERIMENTAL DESIGN AND RESULTS: GPCR CL is transported to the cell surface and recognized by AM only when terminally/mature glycosylated. The presence and localization of this form of the receptor in tumor and surrounding myometrial tissues obtained from leiomyoma-bearing uteri were examined using deglycosylation, immunoblotting, and immunofluorescence analysis. The mature CL glycoprotein was expressed in both tissues and localized exclusively in normal and tumor endothelium within leiomyoma-bearing uteri. The functionality of the receptor expressed in myometrial microvascular endothelial cells (MMVEC) was examined in vitro using receptor internalization and angiogenic assays. The mature CL glycoprotein expressed by primary MMVECs was functional because AM interacted with this GPCR and induced its internalization as well as angiogenic effects (proliferation and migration) in MMVECs in vitro. Finally, the levels of tissue-expressed mature CL glycoprotein as a functional form of this GPCR were analyzed by immunoblotting. The expression of this functional form of the receptor in vivo was significantly decreased (P = 0.01) in leiomyoma tissue, and this was concurrent with the decrease in microvascular density (measured by Chalkley counting) in tumor compared with surrounding myometrium (P = 0.031). CONCLUSIONS: Our findings suggest that GPCR CL mediates angiogenic effects of AM in myometrium and that further evaluation of the properties of the CL expressed in both normal and tumor endothelium in vivo may be essential before targeting this endothelial GPCR for antiangiogenic therapies.
Assuntos
Endotélio Vascular/metabolismo , Leiomioma/metabolismo , Microcirculação/patologia , Neovascularização Patológica/patologia , Receptores da Calcitonina/metabolismo , Neoplasias Uterinas/metabolismo , Adrenomedulina , Adulto , Proteína Semelhante a Receptor de Calcitonina , Endotélio Vascular/patologia , Feminino , Glicosilação , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Leiomioma/irrigação sanguínea , Leiomioma/patologia , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade , Miométrio/metabolismo , Miométrio/patologia , Peptídeos/farmacologia , Proteínas Modificadoras da Atividade de Receptores , Neoplasias Uterinas/irrigação sanguínea , Neoplasias Uterinas/patologiaRESUMO
Adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) are related peptides with distinct pharmacological profiles. Calcitonin-receptor-like receptor (CRLR, now known as CL) can function as either an AM receptor or a CGRP receptor, when cotransfected with receptor-activity-modifying proteins (RAMPs) that define ligand-binding specificity. The aim of the present study was to determine the role of endogenously expressed CL (EndoCL) in generating endogenous AM and CGRP receptors. We raised anti-human CL antibody and identified microvascular endothelial cells (MVECs) as a major CL-expressing cell type in tissues by immunohistochemistry. Cultured MVECs continue to express EndoCL as well as fully active endogenous AM- and CGRP-sensitive receptors in vitro, as demonstrated by the ability of both peptides to induce migration and Akt phosphorylation. We therefore tested the hypothesis that endothelial EndoCL can interact with both AM and CGRP by examining receptor internalisation and desensitisation (loss of the ability to induce Akt phosphorylation). We found that agonist-mediated internalisation of EndoCL occurs in response to AM but not CGRP in MVECs. However, AM-induced EndoCL internalisation was blocked by antagonists of both AM and CGRP receptors: AM(22-52) and CGRP(8-37), respectively. Furthermore, AM-induced EndoCL internalisation resulted in desensitisation not only of AM but also of CGRP receptors. Finally, CGRP also induced desensitisation of both endogenous AM and CGRP receptors, but did not mediate EndoCL internalisation despite interaction with this receptor. Thus, EndoCL interacts with both AM and CGRP, and simultaneously acts as a receptor for both peptides (i.e acting as an endogenous AM/CGRP receptor) in endothelial cells. Interaction with either ligand is sufficient to induce EndoCL desensitisation to both AM and CGRP, but differential mechanisms are involved since only AM induces EndoCL internalisation. These novel findings regarding regulation of EndoCL function in endothelial cells are likely to be of importance in conditions where AM or CGRP levels are elevated, such as cardiovascular disease, diabetes and inflammation.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Células Endoteliais/metabolismo , Peptídeos/metabolismo , Receptores da Calcitonina/metabolismo , Adrenomedulina , Proteína Semelhante a Receptor de Calcitonina , Linhagem Celular , Células Cultivadas , Células Endoteliais/citologia , Regulação da Expressão Gênica , Humanos , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Modificadoras da Atividade de Receptores , Receptores de Adrenomedulina , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/biossíntese , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/fisiologia , Receptores de Peptídeos/biossíntese , Receptores de Peptídeos/fisiologia , Sensibilidade e EspecificidadeRESUMO
Adrenomedullin is a 52 amino acid peptide originally isolated from human phaeochromocytoma in 1993. It was initially demonstrated to have profound effects on the vasculature including vasodilatation and subsequently promotion of angiogenesis. Since then it has become apparent that it has a wide range of other biological actions including regulation of cell growth and differentiation. Successful pregnancy outcome relies on establishing and maintaining throughout gestation an efficient blood supply to the fetus. This allows the exchange of nutrients, oxygenation of fetal blood and removal of cytotoxins from the fetus, such as carbon dioxide. One of the most important local adaptations to pregnancy is the change in maternal blood flow to the implantation site. Evidence now points towards a vital role for adrenomedullin in the regulation of placentation. It appears that adrenomedullin may play important roles in the regulation of fetal perfusion both in normal and in compromised pregnancies. However, most studies have focused on measuring adrenomedullin levels and studying its expression as well as that of its receptors. More functional studies are now required to elucidate the underlying mechanisms involved.