Fig. 9. Schematic models illustrating dynamic gene expressions during induction of adipogenic differentiation and roles of stomatin in promoting fatty acid uptake and lipid droplet enlargement in adipocytes.
a Dynamics expression patterns of stomatin, adipogenic genes C/EBPβ, C/EBPδ, C/EBPα, and PPARγ along the adipogenic differentiation process are depicted. Stomatin progressively increases during adipogenesis and may participate in modulation of other adipogenic gene. By inhibiting pERK, stomatin activates PPARγ, as a prelude to adipogenesis. Stomatin may also directly activate PPARγ pathway through currently unknown mechanisms. b Stomatin and calveolin-1 are known to associated with lipid raft (shadowed red). Stomatin proteins are present on the surfaces of LDs, together with perilipin. Stomatin can promote enlargement of LDs through facilitating LD-LD fusion (a → b → c). The presence of LCFAs outside the cell, through currently unknown mechanisms, relocates stomatin proteins from LDs to lipid rafts on the plasma membrane (1→2), where they interact with CD36 and possibly other FABPs, to promote uptake of LCFAs (3), resulting in increase of intracellular triglycerides, which are transported and stored in LDs (4).