Figure 4: TSC22D4 acts via the LCN13 endocrine system.
From: Control of diabetic hyperglycaemia and insulin resistance through TSC22D4
(a) Chromatin immunoprecipitation of LCN13 promoter regions (1–3) by antibodies against TSC22D4 in livers of wild-type mice. Fold enrichment relative to negative isotype control IgG is determined by qPCR. Region 4 represents a negative PCR control (n=2–3). Similar results were obtained by using a different TSC22D4 antibody. (b) Quantitative PCR analysis of LCN13 in livers of control or TSC22D4 shRNA adenovirus-injected wild-type C57Bl/6 (left), db/db (middle), and NZO mice (below) (means± s.e.m., n≥ 6 for each experiment). (c) Serum from control (NC shRNA) or TSC22D4 (TSC shRNA) shRNA adenovirus–injected C57Bl/6 mice 7 days after injection was immunoblotted with LCN13 antibody. Albumin antibody was used as loading control. (d) Representative western blot from control (PBS) or LCN13 (200 nM)-treated C2C12 myotube extracts using indicated antibodies. LCN13 (3 h) and insulin treatment for 15 min (30 nM) indicated, respectively. Right: densitometric analysis shown. **Indicates effect of insulin; ##Indicates effect of LCN13. (e) Glucose tolerance test in control (control shRNA), LCN13 (LCN13 shRNA), TSC22D4 (TSC22D4 shRNA), TSC22D4 plus LCN13 (TSC22D4 +LCN13 shRNA) shRNA adenovirus–injected db/db mice 1 week after injection. Glucose was injected i.p. at a concentration of 1 g glucose kg−1 body weight. *Indicates significance between NC and TSC22D4 group; #Indicates significance between TSC22D4 and TSC22D4 +LCN13 group; $Indicates significance between NC and TSC22D4 +LCN13 group, (means±s.e.m., n≥6). (f) HOMA-IR index in same mice as in e. (g) Serum glucose levels in same mice as in e. (h) Body weight of mice as in e. (i) Abdominal white adipose tissue (aWAT) mass in same mice as in e. (j) Inguinal white adipose tissue (iWAT) in same mice as in e. Statistical analysis: Student’s t-test, *P≤0.05; **P≤0.01; ***P≤0.001, #P≤0.05; ##P≤0.01; ###P≤0.001, $P≤0.05; $$P≤0.01; $$$P≤0.001.
