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Loss of function effect of RET mutations causing Hirschsprung disease
B Pasini1, M G Borrello, A Greco
1Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, Genova Quarto, Italy.
Nature Genetics
|May 1, 1995
Summary
Three Hirschsprung (HSCR) mutations in the RET gene tyrosine kinase domain abolish RET/PTC2 oncogene activity. These findings suggest a dominant-negative loss-of-function mechanism for HSCR mutations.
Area of Science:
- Genetics
- Molecular Biology
- Oncology
Background:
- Hirschsprung disease (HSCR) is a congenital disorder.
- The RET proto-oncogene plays a critical role in HSCR pathogenesis.
- Mutations in the RET tyrosine kinase domain are implicated in HSCR.
Purpose of the Study:
- To investigate the functional impact of HSCR mutations in the RET tyrosine kinase domain.
- To establish a model system for distinguishing causative HSCR mutations from polymorphisms.
Main Methods:
- Introduction of three HSCR mutations and one polymorphism into the RET/PTC2 chimaeric oncogene.
- Assessment of RET/PTC2 transforming activity in NIH3T3 mouse fibroblasts.
- Evaluation of RET/PTC2 differentiation activity in PC12 rat pheochromocytoma cells.
- Measurement of RET/PTC2 tyrosine phosphorylation levels.
Main Results:
- HSCR mutations abolished RET/PTC2 transforming and differentiation activities.
- These mutations significantly decreased RET/PTC2 tyrosine phosphorylation.
- A rare exon 18 polymorphism did not affect RET/PTC2 activity or phosphorylation.
Conclusions:
- HSCR mutations in the RET tyrosine kinase domain likely exert a dominant-negative loss-of-function effect.
- The developed model system can differentiate between causative HSCR mutations and rare RET polymorphisms.