International Journal of Obesity https://doi.org/10.1038/s41366-019-0367-3 ARTICLE Adipocyte and Cell Biology GALNT2 as a novel modulator of adipogenesis and adipocyte insulin signaling Antonella Marucci 1 ● Alessandra Antonucci 1,2 ● Concetta De Bonis 1 ● Davide Mangiacotti 1 ● Maria Giovanna Scarale 1 ● Vincenzo Trischitta 1,3 ● Rosa Di Paola 1 Received: 12 September 2018 / Revised: 25 February 2019 / Accepted: 15 March 2019 © Springer Nature Limited 2019 Abstract Background/objectives A better understanding of adipose tissue biology is crucial to tackle insulin resistance and eventually coronary heart disease and diabetes, leading causes of morbidity and mortality worldwide. GALNT2, a GalNAc-transferase, positively modulates insulin signaling in human liver cells by down-regulating ENPP1, an insulin signaling inhibitor. GALNT2 expression is increased in adipose tissue of obese as compared to that of non-obese individuals. Whether this association is secondary to a GALNT2-insulin sensitizing effect exerted also in adipocytes is unknown. We then investigated in mouse 3T3-L1 adipocytes the GALNT2 effect on adipogenesis, insulin signaling and expression levels of both Enpp1 and 72 adipogenesis-related genes. Methods Stable over-expressing GALNT2 and GFP preadipocytes (T 0 ) were generated. Adipogenesis was induced with (R +) or without (R-) rosiglitazone and investigated after 15 days (T 15 ). Lipid accumulation (by Oil Red-O staining) and intracellular triglycerides (by fluorimetric assay) were measured. Lipid droplets (LD) measures were analyzed at confocal microscope. Gene expression was assessed by RT-PCR and insulin-induced insulin receptor (IR), IRS1, JNK and AKT phosphorylation by Western blot. Results Lipid accumulation, triglycerides and LD measures progressively increased from T 0 to T 15 R- and furthermore to T 15 R+. Such increases were significantly higher in GALNT2 than in GFP cells so that, as compared to T 15 R+GFP, T 15 R- GALNT2 cells showed similar (intracellular lipid and triglycerides accumulation) or even higher (LD measures, p < 0.01) values. In GALNT2 preadipocytes, insulin-induced IR, IRS1 and AKT activation was higher than that in GFP cells. GALNT2 effect was totally abolished during adipocyte maturation and completely reversed at late stage maturation. Such GALNT2 effect trajectory was paralleled by coordinated changes in the expression of Enpp1 and adipocyte-maturation key genes. Conclusions GALNT2 is a novel modulator of adipogenesis and related cellular phenotypes, thus becoming a potential target for tackling the obesity epidemics and its devastating sequelae. Introduction Obesity and adipose tissue dysfunction are major movers of insulin resistance, thus predisposing to leading causes of morbidity and mortality [1], such as coronary heart disease and type 2 diabetes [2]. A better understanding of the mechanisms controlling adipogenesis is therefore of crucial importance. These authors contributed equally: Antonella Marucci, Alessandra Antonucci * Vincenzo Trischitta vincenzo.trischitta@operapadrepio.it * Rosa Di Paola r.dipaola@operapadrepio.it 1 Research Unit of Diabetes and Endocrine Diseases, Fondazione IRCCS “Casa Sollievo della Sofferenza”, San Giovanni Rotondo, Italy 2 Department of Molecular Medicine, Sapienza University, Rome, Italy 3 Department of Experimental Medicine, Sapienza University, Rome, Italy Supplementary information The online version of this article (https:// doi.org/10.1038/s41366-019-0367-3) contains supplementary material, which is available to authorized users. 1234567890();,: 1234567890();,: