(A and B) Immunofluorescence localization of FSP27 (A) and perilipin (B) in HW adipocytes by confocal laser microscopy. TAG was stained with Bodipy 493/503. (C) Immunoblot analysis of FSP27, perilipin, and β-actin (control) in HW adipocytes 2 days after the introduction of FSP27 or perilipin siRNAs as indicated. (D) Pattern of lipid droplet accumulation in HW adipocytes 2 days after siRNA introduction as in C. TAG was stained with Bodipy 493/503. (E) Glycerol release of HW adipocytes during incubation for 4 or 8 hours, 2 days after introduction of siRNAs as in C. Data are mean ± SEM (n = 6) and are expressed relative to the value for control cells incubated for 4 hours. *P < 0.01 versus corresponding value for control siRNA; **P < 0.01 versus corresponding value for FSP27 or perilipin siRNA. (F) Glycerol release of HW adipocytes during incubation for 40 minutes with 10 μM isoproterenol 2 days after introduction of siRNAs as in C. Data are mean ± SEM (n = 5) and are expressed relative to the value for control cells. *P < 0.01 versus corresponding value for control siRNA; ^†P < 0.01 versus corresponding value for perilipin siRNA. (G) Isolated white adipocytes of wild-type or FSP27-KO mice were incubated for 60 minutes in the absence (basal) or presence of 10 μM isoproterenol, after which concentrations of FFAs (left panel) and glycerol (right panel) in the culture medium were measured. Data are mean ± SEM (n = 5 WT or 4 KO for FFAs; n = 4 for glycerol) and are expressed relative to the corresponding basal value for wild-type cells. ^§P < 0.05, ^§§P < 0.01 versus corresponding value for wild type. (H) Serum FFA (left panel) and glycerol (right panel) concentrations in wild-type and FSP27-KO mice measured 20 minutes after intraperitoneal injection of CL316,243 (0.1 mg/kg) or vehicle. Data are mean ± SEM (n = 4 WT or 3 KO) and are expressed relative to the corresponding basal value for wild-type mice. Original magnification, ×630.