Intragenic suppression of a constitutively active allele of Gsα associated with McCune–Albright syndrome

Tobar-Rubin, Raquel; Sultan, Dahlia; Janevska, Daniela; Turcic, Kyle; Carroll, Julie M.; Ooms, Laura S.; Pals-Rylaarsdam, Robin

doi:10.1530/jme-12-0087

Cited by 3 publications

(2 citation statements)

References 26 publications

(24 reference statements)

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“…These results reinforce the usefulness of yeast expression systems for large-scale random mutagenesis when asking questions relating the structure of a protein to its function (Apanovitch et al 1998, Tobar-Rubin et al 2013). …”

Section: Discussionsupporting

confidence: 62%

“…Thus, the effects of these intragenic suppressors in the absence of the R201H mutation are important to assess in order to wisely choose potential drug targets. For example, a pilot screen from our laboratory identified a suppressor that was constitutively active on its own (Tobar-Rubin et al 2013), making that site a poor choice for drug targeting. Basal and hCG-stimulated cAMP production was measured in transfected cells expressing LHR and various mutant forms of Gs.…”

Section: Resultsmentioning

confidence: 99%

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

Turcic

Tobar-Rubin

Janevska

et al. 2014

Journal of Molecular Endocrinology

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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.

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Section: Discussionsupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

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

Turcic

Tobar-Rubin

Janevska

et al. 2014

Journal of Molecular Endocrinology

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Tuning intracellular homeostasis of human uroporphyrinogen III synthase by enzyme engineering at a single hotspot of congenital erythropoietic porphyria

Bdira

González

Pluta

et al. 2014

Human Molecular Genetics

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Congenital erythropoietic porphyria (CEP) results from a deficiency in uroporphyrinogen III synthase enzyme (UROIIIS) activity that ultimately stems from deleterious mutations in the uroS gene. C73 is a hotspot for these mutations and a C73R substitution, which drastically reduces the enzyme activity and stability, is found in almost one-third of all reported CEP cases. Here, we have studied the structural basis, by which mutations in this hotspot lead to UROIIIS destabilization. First, a strong interdependency is observed between the volume of the side chain at position 73 and the folded protein. Moreover, there is a correlation between the in vitro half-life of the mutated proteins and their expression levels in eukaryotic cell lines. Molecular modelling was used to rationalize the results, showing that the mutation site is coupled to the hinge region separating the two domains. Namely, mutations at position 73 modulate the inter-domain closure and ultimately affect protein stability. By incorporating residues capable of interacting with R73 to stabilize the hinge region, catalytic activity was fully restored and a moderate increase in the kinetic stability of the enzyme was observed. These results provide an unprecedented rationale for a destabilizing missense mutation and pave the way for the effective design of molecular chaperones as a therapy against CEP.

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Case report: Surgical treatment of McCune-Albright syndrome with hyperthyroidism and retrosternal goiter: A case report and literature review

et al. 2023

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IntroductionMcCune-Albright syndrome (MAS) is a low-incidence syndrome consisting of the clinical triad of fibrous structural dysplasia of bone, endocrine disease, and skin pigmentation. Thyroid dysfunction is the second most common endocrine dysregulation in MAS. However, there are no treatment guidelines for MAS complicated with hyperthyroidism. Notably, no case of MAS complicated with retrosternal goiter and hyperthyroidism has been reported to our knowledge.Case presentationWe report a 27-year-old man with MAS who developed the typical triad of bone fibrous dysplasia, skin pigmentation and hyperthyroidism, complaining of recent fast-growing neck mass and difficulty in breathing. Hyperthyrodism was under control by Thiamazole, and computed tomography showed an enlarged thyroid extending retrosternally. We performed a total thyroidectomy on the patient. At the 1-year follow-up, the patient's dyspnea, hyperthyroidism, and bone pain were all significantly alleviated.ReviewWe searched the literature for previous case reports concerning MAS patients complicated with thyroid dysregulation. A total of 17 articles and 22 patients were identified to form our database. Among them, 9 studies clearly mentioned surgical intervention in 11 patients, and prognoses were also reported. Surgery was the most common intervention chosen and indicated a satisfactory prognosis.ConclusionWe report a rare case of MAS patient complicated with retrosternal goiter and hyperthyroidism. Our review provides an overview of MAS cases requiring interventions on thyroid function, and total thyroidectomy should be a proper treatment for these patients.

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Intragenic suppression of a constitutively active allele of Gsα associated with McCune–Albright syndrome

Cited by 3 publications

References 26 publications

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

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

Tuning intracellular homeostasis of human uroporphyrinogen III synthase by enzyme engineering at a single hotspot of congenital erythropoietic porphyria

Case report: Surgical treatment of McCune-Albright syndrome with hyperthyroidism and retrosternal goiter: A case report and literature review

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