title: Regulation of gene expression in cultured embryonic mouse mandibular mesenchyme by serotonin antagonists.
abstract: During murine embryogenesis, uptake sites for the neurotransmitter serotonin (5-HT) are transiently expressed in craniofacial epithelial structures. Based on malformations produced in cultured mouse embryos exposed to uptake inhibitors or receptor ligands, we have proposed that 5-HT acts as a dose-dependent morphogenetic signal during critical periods of craniofacial development. Several 5-HT receptor subtypes are co-distributed with tenascin and the calcium binding protein S-100 beta in developing craniofacial mesenchyme. Since these molecules are thought to be important for craniofacial development, their regulation by 5-HT could mediate some of its morphogenetic actions. Mandibular mesenchyme cells, from E12 mouse embryos (plug day = E1), grown in micromass cultures were used as an in vitro model to investigate whether 5-HT regulates expression of these molecules. Immunocytochemistry revealed expression of S-100 beta, tenascin, cartilage proteoglycan core protein (a component of the cartilage matrix) and a variety of 5-HT receptors in these cultures. To block the actions of 5-HT (from serum in the culture medium), cultures were exposed to one of these selective 5-HT receptor antagonists and effects on expression were investigated using quantitative immunobinding and in situ hybridization assays. These antagonists differentially regulated expression of cartilage core protein, S-100 beta and tenascin. Antagonism of 5-HT3 receptors by Zofran or 5-HT1A receptors by NAN-190 reduced the amount of core protein, whereas antagonism of 5-HT2A-C receptors by mianserin had no significant effect. All three antagonists stimulated levels of tenascin mRNA and protein. Expression of S-100 beta mRNA and protein was inhibited by Zofran and stimulated by mianserin, whereas NAN-190 had no significant effect. The differential effects of antagonists suggest that in vivo, 5-HT could: (1) promote expression of cartilage core protein by activation of 5-HT3 or 5-HT1A receptors, (2) inhibit production of tenascin by activation of multiple receptors, (3) promote or inhibit synthesis of S-100 beta by activation of 5-HT3 or 5-HT2 receptors, respectively. These actions may be important components of the morphogenetic functions of 5-HT during craniofacial development.
authors.affiliation: Department of Cell Biology and Anatomy, School of Medicine, University of North Carolina, Chapel Hill, 27599-7090, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Moiseiwitsch
authors.forename: J M
authors.initials: JM
authors.lastname: Lauder
mesh_terms: D053674:Aggrecans; D000818:Animals; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000187:drug effects / Q000378:metabolism; D046508:Culture Techniques; D016326:Extracellular Matrix Proteins; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D037181:Lectins, C-Type; D008334:Mandible / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008803:Mianserin / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D009414:Nerve Growth Factors; D017294:Ondansetron / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011247:Pregnancy; D011509:Proteoglycans / Q000187:drug effects / Q000378:metabolism; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000187:drug effects / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology*; D019063:Tenascin / Q000187:drug effects / Q000378:metabolism
chemical_list: C508320:Acan protein, mouse; D053674:Aggrecans; D002135:Calcium-Binding Proteins; D011508:Chondroitin Sulfate Proteoglycans; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D009414:Nerve Growth Factors; D010879:Piperazines; D011509:Proteoglycans; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D012702:Serotonin Antagonists; D019063:Tenascin; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; D008803:Mianserin; D017294:Ondansetron