Loss of function effect of RET mutations causing Hirschsprung disease

15nononeWe have introduced three Hirschsprung (HSCR) mutations localized in the tyrosine kinase domain of RET into the RET/PTC2 chimaeric oncogene which is capable of transforming NIH3T3 mouse fibroblasts and of differentiating pC12 rat pheochromocytoma cells. The three HSCR mutations abolished the biological activity of RET/PTC2 in both cell types and significantly decreased its tyrosine phosphorylation. By contrast, a rare polymorphism in exon 18 does not alter the transforming capability of RET/PTC2 or its tyrosine phosphorylation. These data suggest a loss of function effect of HSCR mutations which might act through a dominant negative mechanism. Our model system is therefore capable of discriminating between causative HSCR mutations and rare polymorphisms in the tyrosine kinase domain of RET.nonePASINI, B; BORRELLO, M.G. ; GRECO, A.; BONGARZONE, I.; YIN, L.; MONDELLINI, P.; ALBERTI, L.; MIRANDA, C.; ARIGHI, E.; BOCCIARDI, R.; SERI, M.; BARONE, V. ; RADICE, M.T. ; ROMEO, G.; PIEROTTI, M.A.Pasini, B; Borrello, M. G.; Greco, A.; Bongarzone, I.; Yin, L.; Mondellini, P.; Alberti, L.; Miranda, C.; Arighi, E.; Bocciardi, R.; Seri, M.; Barone, V.; Radice, M. T.; Romeo, G.; Pierotti, M. A