Polymorphic variants of the FTO (fat mass and obesity) gene associate with body mass index in humans, but the underlying molecular mechanisms have not been firmly determined. FTO is linked to energy homeostasis via amino acid sensing and is thought to activate the mammalian target of rapamycin complex 1, a negative regulator of autophagy. FTO localises both to the nucleus and the cytoplasm, and in this study we identify a functional nuclear localisation signal (NLS) in the N-terminus of FTO, as well as nuclear localization information in its very C-terminus. Inhibition of FTO nuclear transport has no effect on autophagy and in contrast to a previously proposed role of FTO in autophagy, we find no difference in starvation-induced autophagy in control cells compared to a panel of cell types depleted of FTO. Future studies that further characterise the cellular functions of FTO will be important to understand why variants in FTO are associated with body weight.
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