endothelin-1 and Hirschsprung-Disease

Topics: Animals; Branchial Region; Cardiovascular Abnormalities; Cardiovascular System; Craniofacial Abnormalities; Endothelin-1; Hirschsprung Disease; Humans; Mice; Mice, Knockout; Neural Crest; Phenotype; Receptor, Endothelin A; Signal Transduction

Topics: Animals; Blood Pressure; Branchial Region; Disease Models, Animal; Endothelin-1; Gene Expression; Hirschsprung Disease; Mice; Mice, Knockout; Neural Crest; Organ Specificity; Receptor, Endothelin A; Receptor, Endothelin B

A series of gene targeting research have revealed novel roles of endothelins (ETs), peptides with potent vasoconstrictive and proliferative activities, in neural crest development in mammals. The phenotype of mice lacking the ET-1/ET-A receptor-mediated signalling affects cranial/cardiac neural crest-derived structures including the branchial arches and great vessels, and is highly similar to a set of the phenotypes of the avian neural crest ablation model. In contrast, mice lacking the ET-3/ET-B receptor-mediated signalling have defects in enteric neurons and melanocytes derived from trunk/vagal neural crest, resulting in megacolon and coat color spotting. Thus, both distinct pathways of the ET system seem to participate in the normal development of different neural crest lineages. Moreover, mutations in the human ET-3 and ET-B receptor genes have been identified in patients with Hirschsprung disease. As for the mechanisms involving the ET system in neural crest development, HANDs and Goosecoid, transcriptional factors essential for embryogenesis, have been suggested as key molecules downstream to the ET-mediated signalling in cranial/cardiac neural crest.

Topics: Animals; Cardiovascular Diseases; Craniofacial Abnormalities; Endothelin-1; Endothelin-3; Endothelins; Gene Expression Regulation, Developmental; Hirschsprung Disease; Humans; Mice; Mice, Knockout; Neural Crest; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin

The endothelin ETB receptor null rat (ETB(-/-)R) has an intestinal segment without ganglia, and this rat is characterised by intestinal obstruction similar to that observed in human Hirschsprung's disease. In the present study, we have examined the myogenic mechanism responsible for obstruction in the ETB(-/-)R.. The ETB(-/-)R had an enlarged belly and the average lifespan was 18.1 days. The bowel from the rectum to the lower part of the small ileum was constricted whereas the upper region was dilated with faecal stasis and thus presented as megaileum. The constricted muscle segments without ganglia had a greater increase in absolute force when stimulated by carbachol, high K+, and endothelin-1 compared with that of normal siblings. In contrast, in the dilated part with ganglia, the absolute contractile force due to these stimulants in the ETB(-/-)R was not different from that in the ETB(+/+)R. Such a functional hypertrophy of the musculature was observed in parts of the colon, caecum, and distal ileum without ganglia but not in the part of the proximal ileum and jejunum with ganglia. Morphological study demonstrated that the thickness of the circular and longitudinal muscle layers was greater in the constricted part of the intestine in the ETB(-/-)R, and these changes were associated with an increase in the number of smooth muscle cells.. Our findings suggest that both increased contractility of smooth muscle and increased thickness of the intestinal muscular wall may contribute to the intestinal obstruction in the ETB(-/-)R.

Topics: Animals; Carbachol; Cholinergic Agonists; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Hirschsprung Disease; Intestines; Muscle Contraction; Muscle, Smooth; Rats; Rats, Mutant Strains; Receptor, Endothelin B; Receptors, Endothelin

Several missense mutations of the endothelin-B receptor (EDNRB) associated with Hirschsprung disease have recently been identified. Five mutated EDNRB (A183G, W276C, R319W, M374I and P383L) cDNAs were transiently expressed in several cell lines to examine the effects of these mutations. Ligand-receptor binding experiments demonstrated that all mutants examined here accept endothelins with a high affinity. Especially, the affinity of endothelins to P383L was increased. However, the number of binding sites of A183G, W276C and P383L was markedly decreased. The subcellular localization of these mutant receptors was the same as that of wild-type EDNRB, whereas the amount of protein of each mutant receptor was decreased. All mutant receptors were impaired in intracellular Ca(2+) mobilization. These findings indicate that these missense mutations result in loss of function of EDNRB, and may provide the molecular pathological basis of Hirschsprung disease in some individuals.

Topics: Animals; Base Sequence; Calcium; COS Cells; DNA Primers; Endothelin-1; Endothelin-3; Hirschsprung Disease; Humans; Ligands; Mutation, Missense; Protein Binding; Receptor, Endothelin B; Receptors, Endothelin

Topics: Animals; Aspartic Acid Endopeptidases; Autonomic Nervous System Diseases; Blotting, Western; CHO Cells; Cricetinae; Endothelin-1; Endothelin-3; Endothelin-Converting Enzymes; Endothelins; Exons; Heart Defects, Congenital; Hirschsprung Disease; Humans; Incidence; Infant, Newborn; Metalloendopeptidases; Molecular Sequence Data; Mutation; Protein Precursors