Molecular cloning and the involvement of IRE1 alpha-XBP1s signaling pathway in palmitic acid induced - Inflammation in primary hepatocytes from large yellow croaker (Larimichthys crocea)

摘要

Apart from mitigating endoplasmic reticulum (ER) stress, vast studies have demonstrated the crucial role of inositol-requiring transmembrane kinase and endonuclease 1 alpha (IRE1 alpha) - spliced X-box binding protein 1 (XBP1s) signaling pathway in inflammatory response in mammals. In addition, palmitic acid (PA)-induced inflammation has been verified in large yellow croaker (Larimichthys crocea). However, whether the IRE1 alpha 2-XBP1s signaling pathway is involved in inflammatory response caused by PA remains poorly studied in fish. The present study was aimed at elucidating the role of the IRE1 alpha-XBP1s signaling pathway in inflammatory response induced by PA in primary hepatocytes from large yellow croaker. In the present study, the full-length cDNA of ire1 alpha and xbp1s were cloned and comprised 3793 bp and 1789 bp with an open reading frame of 3279 bp and 1170 bp, encoding 1093 and 390 amino acids, respectively. IRE1 alpha protein possessed a protein kinase and endoribonuclease domain and XBP1s protein possessed a basic-leucine zipper domain. The IRE1 alpha protein and XBP1s protein located to the ER membrane and nucleus respectively. The ire1 alpha and xbp1s were widely transcribed in various tissues with the higher level in intestine, liver, adipose and head kidney. The ER stress-inducing agent tunicamycin (Tm) and PA treatment significantly activated the IRE1 alpha-XBP1s signaling pathway and increased the pro-inflammatory genes expression including tumor necrosis factor alpha (tnfa), interleukin 6 (il-6) and interleukin 1 beta (il-1 beta) (P < 0.05). When KIRA6, the IRE1 alpha kinase inhibitor, was used to block the IRE1 alpha-XBP1s signaling pathway, the Tm and PA-induced pro-inflammatory genes expression was significantly suppressed (P < 0.05). These data indicated that the IRE1 alpha-XBP1s signaling pathway was involved in the PA-induced inflammatory response in large yellow croaker.