Schematic overview of the selected lipogenic genes and their function.

Adipogenesis is characterized by the expression of PPARγ, C/EBP-family members and SREBP. Insulin, glucocorticoids or IGF stimulate the expression of C/EBPβ, which in turn stimulates the expression of EBPα and PPARγ. Upon stimulation, PPARγ forms a heterodimer with RXR and together with EBPα regulate the expression of genes involved in adipogenesis and lipogenesis [26]. C/EBPα and C/EBPβ also regulate the expression of 11β-HSD1 and 11β-HSD2 (which catalyse the activation and deactivation, respectively, of cortisol and regulate glucocorticoid metabolism) [40] and of IGF-I and IGF-II (which regulate growth, cell proliferation and development) [41, 42]. SREBP1 and ChREBP, are stimulated upon insulin and glucose secretion, respectively, and regulate synergistically the expression of the de novo lipogenesis enzymes FASn and ACCα [43] that catalyse fatty acid synthesis. SREBP1 also regulates the expression of PPARγ [44]. Fatty acid catabolism through β-oxidation in peroxisomes is catalysed by ACOX1 [45]. Excess fatty acids derived from food, break-down from stored fat or synthesized through de novo lipogenesis are converted to triglycerides through a pathway the last step of which is catalysed by the DGAT2 enzyme. The transcriptional regulation of DGAT2 is also regulated by EBPβ and to a lesser extent by EBPα [46].