Fig. 1

Regulations of PLIN5 expression in pancreatic islets and INS-1 β-cells. a Upregulation of islet PLIN5 protein expression in high fat diet (HFD) fed mice (left, n = 4 pooled samples for each group) and ob/ob obesity mice (right, n = 3 samples for each group) compared with chow diet fed (CHOW) mice or control mice (Con). Pancreatic islet PLIN5 protein expression was detected from C57BL/6 J mice treated with chow food or HFD for 5 months and 16-week old ob/ob mice or the control mice. **P < 0.05 vs CHOW or control (Con). b Serum FFA levels were comparable between CHOW mice and HFD mice (n = 8 for each group). After 5-month food manipulation, serum FFA concentrations were measured using a commercial kit. c Time course of palmitate (PA) treatment on gene (left) and protein (right) expression of PLIN5. INS-1 cells were treated with 0.5 mM PA for 0, 1, 3, 6, and 12 h (n = 3 for each group in three independent experiments). Abundance of PLIN5 was detected by quantitative real-time RT-PCR (Q-PCR) and Western blot. For Q-PCR, the mRNA level was expressed as the percentage of control (0 h). Values are means ± SE. **P < 0.01 vs. 0 h. d PLIN5 is a PPAR target gene in INS-1 β-cells (n = 3 for each group in three independent experiments). Cells were exposed to 10 μM WY-14643 (PPARα agonist) or 10 μM GW501516 (PPARβ/δ agonist) or 10 μM rosiglitazone (PPARγ agonist) for 24 h and expression of PLIN5 was monitored by Western blot (upper). A luciferase reporter assay was conducted to verify the interactions between PLIN5 and PPARs (down). INS-1 cells were transfected with PLIN5-luciferase reporter vector and then treated with three PPAR agonists for 24 h, respectively. After that, luciferase activity was measured which is the ratio between firefly luciferase and Renilla control luciferase. Values are means ± SE. **P < 0.01 vs. PLIN5-Luc