Optical microscopy approach to investigate changes in chromatin organization during adipocyte differentiation and hypertrophy.

The adipose tissue is the physiological energy and fat store acting also in endocrine regulation of metabolic homeostasis. Adipocyte hypertrophy occurring in obesity refers to an increase in adipocyte size due to lipid droplets enlargement. Our aim is to investigate the nuclear architecture and epigenetics during adipocyte differentiation and hypertrophy using an $in vitro$ model of 3T3-L1 preadipocytes firstly differentiated into mature adipocytes, then cultured with fatty acids to induce hypertrophy. On mature and hypertrophic adipocytes, we assessed lipid accumulation as a marker of hypertrophy. Through confocal and super-resolution STED microscopy we assessed the remodelling of nuclear architecture. By immunoassay we quantified the average changes in the DNA methylation (5-mc). Confocal and STED analyses show appreciable differences in the nuclear architecture DNA methylation average between mature and hypertrophic adipocytes. Taken together, these preliminary results indicate a remodelling of both epigenome and nuclear organization during adipocyte differentiation and hypertrophy thus paving the way toward new strategies to treat/prevent obesity and its metabolic complication.