Elucidation of the role of the molecular chaperone AIP in familial acromegaly
Lead Research Organisation:
Queen Mary University of London
Department Name: William Harvey Research Institute
Abstract
Recently abnormal changes (mutations) in the AIP (aryl-hydrocarbon receptor-interacting protein) gene have been shown to result in familial pituitary tumours with excess growth hormone causing abnormally tall stature (gigantism) or enlargement of the hands, feet and other organs(acromegaly). This project will investigate the function of AIP and the exact way by which mutations in the AIP gene results in acromegaly. The project will study the characteristics and function of normal and mutated AIP protein in cell lines and tissues. We will make cells with elevated levels of both normal and abnormal AIP. We will also reduce AIP levels in cells. In both instances we will compare the characteristics to normal cells. We will further characterise our familial acromegaly patients, one of the largest collections in the world, in terms of clinical features and the type of tumour they have. We believe that exploring how this gene works in this relatively rare familial disease will allow us to understand the physiology and pathophysiology of pituitary cells and possibly the more common sporadic pituitary adenomas. This project therefore will provide a balanced training both in laboratory science and in clinical research, allowing the applicant to learn essential skills, which will be valuable for his long-term goal of working in academic medicine.
Technical Summary
Aims of the project
1. to characterise the effect of wild-type and mutant AIP on cell proliferation
2. to dissect the mechanisms by which mutation of AIP leads to somatotroph adenomas
3. to clinically characterise our cohort of familial pituitary adenoma patients and a geographical cluster of patients with acromegaly.
Mutations have been identified in the AIP (aryl-hydrocarbon receptor (AhR)-interacting protein) gene in patients with familial pituitary adenomas, especially familial acromegaly. This proposal focuses on the mechanism by which a lack of AIP results in tumorigenesis. First, we will establish that AIP has an effect on cell proliferation and that this effect is abolished by mutations identified in patients. The effect of inhibition of endogenous AIP using siRNA will then be studied in GH3 cells. We hypothesise that AIP will stimulate Zac1, a gene known to be involved in pituitary tumorigenesis and influenced by somatostatin. We will study Zac1 expression and promoter activity in response to wild-type and mutant AIP. The cAMP-pathway, known to be critical in somatotroph cell tumorigenesis, is involved in the activation and nuclear-shuttling of AhR and influenced by a phosphodiesterase-AIP complex, and therefore the cellular localisation in the presence of wild-type and mutated AIP will be studied with confocal microscopy. This project will provide an insight into the signalling pathways of AIP-related tumour formation through a balanced training in molecular biology, and the clinical characterisation of our unique familial acromegaly cohort will provide experience in clinical research.
1. to characterise the effect of wild-type and mutant AIP on cell proliferation
2. to dissect the mechanisms by which mutation of AIP leads to somatotroph adenomas
3. to clinically characterise our cohort of familial pituitary adenoma patients and a geographical cluster of patients with acromegaly.
Mutations have been identified in the AIP (aryl-hydrocarbon receptor (AhR)-interacting protein) gene in patients with familial pituitary adenomas, especially familial acromegaly. This proposal focuses on the mechanism by which a lack of AIP results in tumorigenesis. First, we will establish that AIP has an effect on cell proliferation and that this effect is abolished by mutations identified in patients. The effect of inhibition of endogenous AIP using siRNA will then be studied in GH3 cells. We hypothesise that AIP will stimulate Zac1, a gene known to be involved in pituitary tumorigenesis and influenced by somatostatin. We will study Zac1 expression and promoter activity in response to wild-type and mutant AIP. The cAMP-pathway, known to be critical in somatotroph cell tumorigenesis, is involved in the activation and nuclear-shuttling of AhR and influenced by a phosphodiesterase-AIP complex, and therefore the cellular localisation in the presence of wild-type and mutated AIP will be studied with confocal microscopy. This project will provide an insight into the signalling pathways of AIP-related tumour formation through a balanced training in molecular biology, and the clinical characterisation of our unique familial acromegaly cohort will provide experience in clinical research.