Biochemical and Functional Characterization of Germ Line KRAS Mutations

Abstract

Germ line missense mutations in HRAS and KRAS and in genes encoding molecules that function up- or downstream of Ras in cellular signaling networks cause a group of related developmental disorders that includes Costello syndrome, Noonan syndrome, and cardiofaciocutaneous syndrome. We performed detailed biochemical and functional studies of three mutant K-Ras proteins (P34R, D153V, and F156L) found in individuals with Noonan syndrome and cardiofaciocutaneous syndrome. Mutant K-Ras proteins demonstrate a range of gain-of-function effects in different cell types, and biochemical analysis supports the idea that the intrinsic Ras guanosine nucleotide triphosphatase (GTPase) activity, the responsiveness of these proteins to GTPase-activating proteins, and guanine nucleotide dissociation all regulate developmental programs in vivo.

We are indebted to Oddmund Sovik for referring the patient with the F156L mutation for study. We are grateful to David Tuveson for critical comments. We also thank Robert Hawley for providing the MSCV vector and the Laboratory for Cell Analysis Shared resource of the UCSF Comprehensive Cancer Center for assistance with cell sorting.

This work was supported, in part, by NIH grants R37 CA72614 and R01 CA104282.