Metabolic expressivity of human genetic variants: NMR metabotyping of MEN1 pathogenic mutants

Functional consequences of mutations in predisposition genes for familial cancer syndromes remain often elusive, especially when the corresponding gene products play pleiotropic functions and interact with numerous partners. Understanding the consequences of these genetic alterations requires access to their functional effects at the phenotypic level. Nuclear magnetic resonance (NMR) has emerged as a promising functional genomics probe, through its ability to monitor the consequences of genetic variations at the biochemical level. Here, we determine by NMR the metabolic perturbations associated with different disease-related mutations in the MEN1 gene, responsible for the multiple endocrine neoplasia syndrome, type 1 (MEN1), an example of hereditary cancer. The MEN1 gene encodes the Menin protein. Based on a cellular model that allows exogenous overexpression of either the wild type (WT) Menin protein or disease-related variant forms, we evaluate the feasibility of using metabolic profiles to discriminate cells with WT versus variant Menin overexpression. High-resolution magic angle spinning (HRMAS) NMR of whole cells allows to determine the metabolic features associated with overexpression of WT Menin as compared to the one of six different missense variants observed in MEN1 patients. We then identify several statistically significant individual metabolites associated with the metabolic signature of pathogenic versus WT variants. Whether such a metabolic phenotyping approach using cell lines could be exploited as a functional test in a human genetic cancer syndrome is further discussed. (C) 2013 Elsevier B.V. All rights reserved.