Identification of five genes in endoplasmic reticulum (ER) stress-apoptosis pathways in yellow catfish Pelteobagrus fulvidraco and their transcriptional responses to dietary lipid levels

The activating transcription factor 4 (ATF4), DNA damage-inducible transcript 3 (DDIT3), growth arrest, and DNA damage-inducible protein 34 (GADD34), endoplasmic reticulum oxidoreductin 1 alpha (ERO1 alpha), and tumor necrosis factor receptor associated factor 2 (TRAF2) cDNAs were first characterized from yellow catfish Pelteobagrus fulvidraco. Compared to corresponding genes of mammals, all of these proteins shared similar conserved domains. Their mRNAs were widely expressed in various tissues, but at variable levels. Dietary lipid levels did not significantly influence ATF4 mRNA expression. mRNA expression of DDIT3 and GADD34 was highest for fish fed the low-lipid diets and lowest for fish fed middle-lipid diets. The mRNA levels of ERO1 alpha and TRAF2 declined with increasing dietary lipid levels. For the first time, we characterized the full-length cDNA sequences of ATF4, DDIT3, GADD34, ERO1 alpha, and TRAF2 and determined their tissue expression profiles and transcriptional responses to dietary lipid levels, which would contribute to our exploration into their biological functions, and providing new insights on relations between ER stress and lipid metabolism in fish.