In-Vitro-Generated Hypertrophic-Like Adipocytes Displaying <i>PPARG</i> Isoforms Unbalance Recapitulate Adipocyte Dysfunctions In Vivo

• Main Authors: Marianna Aprile, Simona Cataldi, Caterina Perfetto, Maria Rosaria Ambrosio, Paola Italiani, Rosarita Tatè, Matthias Blüher, Alfredo Ciccodicola, Valerio Costa
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Cells
• Subjects: hypertrophic adipocytes; <i>PPARG</i> isoforms; <i>PPARG </i>splicing; dominant-negative isoform; in vitro adipocytes; adipogenesis
• Online Access: https://www.mdpi.com/2073-4409/9/5/1284

Reduced neo-adipogenesis and dysfunctional lipid-overloaded adipocytes are hallmarks of hypertrophic obesity linked to insulin resistance. Identifying molecular features of hypertrophic adipocytes requires appropriate in vitro models. We describe the generation of a model of human hypertrophic-like adipocytes directly comparable to normal adipose cells and the pathologic evolution toward hypertrophic state. We generate in vitro hypertrophic cells from mature adipocytes, differentiated from human mesenchymal stem cells. Combining optical, confocal, and transmission electron microscopy with mRNA/protein quantification, we characterize this cellular model, confirming specific alterations also in subcutaneous adipose tissue. Specifically, we report the generation and morphological/molecular characterization of human normal and hypertrophic-like adipocytes. The latter displays altered morphology and unbalance between canonical and dominant negative (PPARGΔ5) transcripts of <i>PPARG</i>, paralleled by reduced expression of PPARγ targets, including <i>GLUT4</i>. Furthermore, the unbalance of PPARγ isoforms associates with <i>GLUT4</i> down-regulation in subcutaneous adipose tissue of individuals with overweight/obesity or impaired glucose tolerance/type 2 diabetes, but not with normal weight or glucose tolerance. In conclusion, the hypertrophic-like cells described herein are an innovative tool for studying molecular dysfunctions in hypertrophic obesity and the unbalance between PPARγ isoforms associates with down-regulation of<i> GLUT4 </i>and other PPARγ targets, representing a new hallmark of hypertrophic adipocytes.