Three intragenic suppressors of a GTPase-deficient allele of GNAS associated with McCune–Albright syndrome

Abstract

Gain-of-function mutations in heterotrimeric G-protein a subunits are associated with a variety of human diseases. McCune-Albright syndrome (MAS) is caused by mutations in GNAS, the gene encoding Gs. Alterations at Arg201 significantly reduce the GTPase activity of the protein, rendering it constitutively active. In this study, we have constructed a library of random mutations in a constitutively active yeast GPA1 gene carrying a mutation homologous to the McCune-Albright allele (Arg297His). Intragenic suppressors found at sites with homology to the human Gs protein were tested for their ability to suppress the constitutive activity of an Arg201His mutation in Gs. Three intragenic suppressors, at Phe142, Arg231, and Leu266, were able to suppress elevated basal cAMP responses caused by Arg201His when expressed in HEK293 cells. A range of amino acid substitutions was introduced at each of these sites to investigate the chemical requirements for intragenic suppression. The ability of Gs proteins carrying the suppressor mutations alone to mediate receptor-induced cAMP production was measured. These results offer potential sites on Gs that could serve as drug targets for MAS therapies.

Endothelin-1 Pathway Polymorphisms and Outcomes in Pulmonary Arterial Hypertension

“…Whether GNAS activity mediated by ETB stimulation is responsible for this aforementioned cascade is at present unknown. Mutations and sequence variations in this gene lead to a variety of tumors, fibrous dysplasia of bone, and McCune-Albright syndrome (72)(73)(74)(75)(76). In addition, SNPs in the GNAS gene have been shown to predict the postoperative course in solid tumors (77) and may predict benefit from platinum-based neoadjuvant chemoradiotherapy for esophageal cancer (78).…”