The Demethylase Activity of FTO (Fat Mass and Obesity Associated Protein) Is Required for Preadipocyte Differentiation.

Meizi Zhang,Jijie Chai,Jun Ma,Wenqing Zhao,Yu Zhang,Feima Guo,Ying Zhang,Bin Zhou,Qian Cao,Renbin Zhao,Julie A Chowen

doi:10.1371/journal.pone.0133788

Abstract

FTO (fat mass and obesity associated gene) was genetically identified to be associated with body mass index (BMI), presumably through functional regulation of energy homeostasis. However, the cellular and molecular mechanisms by which FTO functions remain largely unknown. Using 3T3-L1 preadipocyte as a model to study the role of FTO in adipogenesis, we demonstrated that FTO is functionally required for 3T3-L1 differentiation. FTO knock-down with siRNA inhibited preadipocyte differentiation, whereas ectopic over-expression of FTO enhanced the process. The demethylase activity of FTO is required for differentiation. Level of N6-methyladenosine (m6A) is decreased in cells over-expressing FTO. In contrast, overexpression of R96Q, a FTO missense mutant lack of demethylase activity, had no effect on cellular m6A level and impeded differentiation. Treatment with Rosiglitazone, a PPARγ agonist, could overcome the differentiation inhibition imposed by R96Q mutant, suggesting the effect of FTO is mediated through PPARγ.

Highlights

Since the original publication of association between genetic variation in FTO and body mass index [1,2,3,4], considerable efforts have been dedicated to elucidating the molecular mechanism of FTO in modulating energy homeostasis
Over-expression of wt FTO in 3T3-L1 cells resulted in significant reduction of m6A level compared to vector transfected cells, whereas the demethylase-deficient mutant R96Q had minimum effect on m6A level (Fig 2D and 2E).These results suggest the N6-methyladenosine demethylase activity of FTO is required during adipocyte maturation
We used mouse 3T3-L1 preadipocyte as a model to study the function of FTO during adipogenesis

Summary

Introduction

Since the original publication of association between genetic variation in FTO and body mass index [1,2,3,4], considerable efforts have been dedicated to elucidating the molecular mechanism of FTO in modulating energy homeostasis. Studies of genetically engineered mouse models have highlighted the level of complexity in uncovering the role of FTO in regulating body composition and energy metabolism[5]. Global germ line KO of FTO resulted in reduced body weight and growth retardation [6,7,8]. While most germ line inactivation or over-expression models support a positive correlation between FTO activity and fat mass[7,8,9], adult onset loss of FTO resulted in increased fat mass and reduced lean mass [10]. Knock-down of FTO activity in a sub-region of hypothalamus only led to mild phenotypes comparing to global inactivation, suggesting FTO exerts function in sites beyond hypothalamus[10].

Methods

Results

Conclusion