Objective: To determine the effects of nuclear factor-alpha B (NF-alpha B) on peroxisome proliferator activated receptor gamma (PPAR gamma) expression in the murine macrophage cell line Ana-1, based on the investigation of the PPAR gamma expression stimulated by lipopolysaccharide (LPS).
Methods: Ana-1 cells were divided randomly into seven groups: control group, LPS groups (cells were activated by 0.1 mg/L LPS for 1, 2, 4, 8 hours respectively), SN50 group (cells were stimulated by 50 mg/L SN50 for 4 hours) and NF-alpha B high expression plasmid transfected group. PPAR gamma and tumor necrosis factor-alpha(TNF-alpha) mRNA levels were assayed by reverse transcription-polymerase chain reaction (RT-PCR) and the TNF-alpha protein was measured by enzyme linked immunosorbent assay (ELISA) after being activated by LPS. The eukaryotic expression vector of murine NF-alpha B p65 gene was constructed and stably transfected into Ana-1 cells with DOTAP liposome . The PPAR gamma expression and NF-alpha B p65 translocation as stimulated by LPS and SN50 were assayed by Western blotting.
Results: Expressions of both PPAR gamma mRNA and protein were downregulated when cells were stimulated by LPS, which were accompanied with the activity of NF-alpha B and TNF-alpha in Ana-1 cells (all P<0.05). The eukaryotic expression vectors containing murine p65 gene were successfully constructed and stably transfected into Ana-1 cells. LPS stimulation and NF-alpha B p65 gene overexpression resulting in upregulation of p65 could downregulate PPAR gamma expression in Ana-1 cells (r=-0.913, P<0.05).But downregulation of NF-alpha B by SN50 could upregulate PPAR gamma expression in the nucleus (r=-0.959, P<0.05).
Conclusion: LPS can markedly decrease the expression of PPAR gamma in Ana-1 cells, which may be related to its activity of enhancing NF-alpha B. NF-alpha B p65 gene can control PPAR gamma expression in the reverse direction in Ana-1 cells.