243 - Adiponectin enhances apolipoprotein A-1 gene expression in HepG2 cells: the studying of AdipoR1 and AdipoR2-dependent signaling pathways. (ID 739)
- Dmitry Tanyanskiy, Russian Federation
- Vladimir S. Shavva, Russian Federation
- Ella Dizhe, Russian Federation
- Galina Oleinikova, Russian Federation
- Alexey V. Lizunov, Russian Federation
- Ekaterina V. Nekrasova, Russian Federation
- Sergey V. Orlov, Russian Federation
- Alexander Denisenko, Russian Federation
Abstract
Background and Aims
Adipose tissue hormone adiponectin is involved in pathogenesis of metabolic syndrome and atherosclerosis. Earlier it was shown that adiponectin increases the expression of apolipoprotein A-1 (apoA-1) gene in human hepatoma cells, HepG2, but signaling mechanisms of this effect remain unknown. The study is dedicated to resolving this issue.
Methods
The study is performed in HepG2 cells, cultivating in standard for this cell type conditions. The expression level of apoA-1 was determined by using RT-PCR and ELISA. For evaluating the signaling pathways, RNA interference was applied. Transfections of the cells with plasmids, containing native or mutant hepatic enhancer, the apoA-1 regulatory element, following by luciferase reporter gene, were performed as well.
Results
Adiponectin and AMP-dependent protein kinase (AMPK) activator AICAR increased the mRNA content of apoA-1 in HepG2 cells. siRNA-knockdown of adiponectin receptors AdipoR1 or AdipoR2 or both abrogated the effect of adiponectin on apoA-1 mRNA level. siRNA-knockdown of AdipoRs’ down-stream signaling molecules AMPK and PPARα, as well as LXRα and LXRβ also prevented adiponectin’s effect on apoA-1 gene transcription. Adiponectin stimulated activity of native hepatic enhancer, but not mutant constructs in sites A and C, which bind PPARα and LXRs, respectively.
Conclusions
Both types of adiponectin receptors, AMPK, PPARα, and LXRs participate in adiponectin-dependent stimulation of apoA-1 gene expression in HepG2 cells.
