Rapid proteasomal degradation of mutant proteins is the primary mechanism leading to tumorigenesis in patients with missense AIP mutations

Hernández-Ramírez, Laura C, Martucci, Federico, Morgan, Rhodri M L, Trivellin, Giampaolo, Tilley, Daniel, Ramos-Guajardo, Nancy, Iacovazzo, Donato, D'Acquisto, Fulvio, Prodromou, Chrisostomos and Korbonits, Márta (2016) Rapid proteasomal degradation of mutant proteins is the primary mechanism leading to tumorigenesis in patients with missense AIP mutations. The Journal of clinical endocrinology and metabolism, 101 (8). 3144 -3154. ISSN 1945-7197

[img] PDF - Published Version
Available under License Creative Commons Attribution.

Download (1MB)

Abstract

CONTEXT

The pathogenic effect of AIP mutations (AIPmuts) in pituitary adenomas is incompletely understood. We have identified the primary mechanism of loss of function for missense AIPmuts.

OBJECTIVE

To analyze the mechanism/speed of protein turnover of wild-type (WT) and missense AIP variants, correlating protein half-life with clinical parameters.

DESIGN

Half-life and protein-protein interaction experiments and cross-sectional analysis of AIPmut positive patients' data were performed.

SETTING

Clinical academic research institution.

PATIENTS

Data was obtained from our cohort of pituitary adenoma patients and literature-reported cases.

INTERVENTIONS

Protein turnover of endogenous AIP in two cell lines and fifteen AIP variants overexpressed in HEK293 cells was analyzed via cycloheximide chase and proteasome inhibition. GST pull-down and quantitative mass spectrometry identified proteins involved in AIP degradation; results were confirmed by co-immunoprecipitation and gene knockdown. Relevant clinical data was collected.

MAIN OUTCOME MEASURES

Half-life of WT and mutant AIP proteins and its correlation with clinical parameters.

RESULTS

Endogenous AIP half-life was similar in HEK293 and lymphoblastoid cells (43.5 and 32.7h). AIP variants were divided in stable proteins (median 77.7h [IQR 60.7-92.9]), and those with short (27h [21.6-28.7]) or very short (7.7h [5.6-10.5]) half-life; proteasomal inhibition rescued the rapid degradation of mutant proteins. The experimental half-life significantly correlated with age at diagnosis of acromegaly/gigantism (r=0.411, P=0.002). The FBXO3-containing SCF complex was identified as the E3 ubiquitin-ligase recognizing AIP.

CONCLUSIONS

AIP is a stable protein, driven to ubiquitination by the SCF complex. Enhanced proteasomal degradation is a novel pathogenic mechanism for AIPmuts, with direct implications for the phenotype.

Item Type: Article
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology Including cancer and carcinogens
Depositing User: Chrisostomos Prodromou
Date Deposited: 06 Jun 2016 13:36
Last Modified: 06 Mar 2017 13:48
URI: http://sro.sussex.ac.uk/id/eprint/61317

View download statistics for this item

📧 Request an update