NAIP EXPRESSION INCREASES IN RAT’S LIVER REGENERATION

Background and objectives: NAIP (NLR family apoptosis inhibitory protein) belongs to the IAP (Inhibitor of Apoptosis Protein) and NLR (NOD-Like Receptor protein) families. As a receptor of pathogen/damaged associated molecular patterns (PAMPs/ DAMPs), NAIP is involved in the innate immune response, and is also a fundamental component of the NLRC4 inflammasome. As such, NAIP participates in caspase-1 activation leading to inflammatory cytokine secretion. Recently, our research group has reported the implication of NAIP in cell proliferation. The aim of this study was to analyze NAIP expression in the hepatic regenerative process. Methods: Eight female Wistar rats weighing 260 g were used. The major liver lobe of the rats was removed. Hepatectomized rats were sacrificed 3 days (n=4) and 7 days (n=4) after surgery, and pieces from both regenerated and healthy liver were taken. Total RNA and proteins were extracted and analyzed by qRT-PCR and western blotting, respectively. Results: NAIP mRNA showed a 3-fold increase at day 3 after hepatectomy, and a 2-fold increase at day 7 after hepatectomy. NAIP protein levels exhibited a 2-fold higher expression in the regenerating liver lobe compared with the intact lobe from the same animal 3 days after hepatectomy. Conclusions: This study shows the implication of NAIP in liver regeneration. Further studies are needed to elucidate the role of NAIP in both cell cycle progression and liver regeneration.