A Drosophila model of GDAP1 function reveals the involvement of insulin signalling in the mitochondria-dependent neuromuscular degeneration

[EN] Charcot-Marie-Tooth disease is a rare peripheral neuropathy for which there is no specific treatment. Some forms of Charcot-Marie-Tooth are due to mutations in the GDAP1 gene. A striking feature of mutations in GDAP1 is that they have a variable clinical manifestation, according to disease onset and progression, histology and mode of inheritance. Studies in cellular and animal models have revealed a role of GDAP1 in mitochondrial morphology and distribution, calcium homeostasis and oxidative stress. To get a better understanding of the disease mechanism we have generated models of over-expression and RNA interference of the Drosophila Gdapl gene. In order to get an overview about the changes that Gdapl mutations cause in our disease model, we have combined a comprehensive determination of the metabolic profile in the flies by nuclear magnetic resonance spectroscopy with gene expression analyses and biophysical tests. Our results revealed that both up- and down-regulation of Gdapl results in an early systemic inactivation of the insulin pathway before the onset of neuromuscular degeneration, followed by an accumulation of carbohydrates and an increase in the (3-oxidation of lipids. Our findings are in line with emerging reports of energy metabolism impairments linked to different types of neural pathologies caused by defective mitochondrial function, which is not surprising given the central role of mitochondria in the control of energy metabolism. The relationship of mitochondrial dynamics with metabolism during neurodegeneration opens new avenues to understand the cause of the disease, and for the discovery of new biomarkers and treatments.This work was supported by a project grant from the Association Francaise contre les Myopathies [AFM 18540 to M.I.G]; a collaborative grant from International Rare Diseases Research consortium (IRDiRC) and Institute de Salud Carlos III [IR11/TREAT-CMT to M.I.G. (partner 12) and F.V.P. (partner 8)]; funding from Institute de Salud Carlos III through Biomedical Network Research Center for Rare Diseases and the INGENIO 2010 program to F.V.P.; and a project grant from the Spanish Government (Secretaria de Estado de Investigacion, Desarollo e Innovacion, Ministerio de Economia y Competitividad) [SAF2014-53977-R to A.P.].Lopez Del Amo, V.; Palomino-Schätzlein, M.; Seco-Cervera, M.; Garcia-Gimenez, JL.; Pallardó-Calatayud, FV.; Pineda-Lucena, A.; Galindo-Orozco, MI. (2017). A Drosophila model of GDAP1 function reveals the involvement of insulin signalling in the mitochondria-dependent neuromuscular degeneration. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease. 1863(3):801-809. https://doi.org/10.1016/j.bbadis.2017.01.003S8018091863