SpATF2 participates in maintaining the homeostasis of hemolymph microbiota by regulating dual oxidase expression in mud crab.

Activating transcription factors 2 (ATF2) is a transcription factor of the members of ATF/CREB family that is phosphorylated and activated by the mitogen-activated protein kinase (MAPK) in responding to the stimulation of stimuli. In present study, Sp ATF2 from mud crab (Scylla paramamosain) was identified and studied. The open reading frame of Sp ATF2 with 2136 bp in length encodes a protein with 711 amino acids. The Sp ATF2 protein includes the putative zinc finger domain in the N-terminus and bZIP type DNA-binding domain in the C-terminal. Tissue distribution of Sp ATF2 transcripts showed that Sp ATF2 was ubiquitously expressed in all examined tissues of the untreated mud crabs, with the highest expression levels in muscle and hepatopancreas. The transcriptional level of Sp ATF2 was up-regulated in the hemocytes after Vibrio parahemolyticus or WSSV infection. Reporter gene assays indicated that Sp ATF2 could activate the expression of dual oxidase (Sp Duox1) in S. paramamosain. The RNA interference (RNAi) of Sp ATF2 significantly decreased the expression of Sp Duox1, and consequently reduced reactive oxygen species production thereby significantly increased the bacterial load in the hemolymph of mud crabs. Similarly, significant reduction in bacterial clearance of hemolymph was observed after the V. parahemolyticus infection in Sp ATF2 knockdown mud crabs. This study showed that Sp ATF2 played a vital role in maintaining homeostasis of the hemolymph microbiota through regulating the expression of dual oxidase of mud crab. • Sp ATF2 regulates the expression of S. paramamosain Doux1 in transcription level. • Sp ATF2 participates in maintaining the homeostasis of the hemolymph microbiota in mud crabs. • The bacterial clearance of hemolymph was significantly reduced in the Sp ATF2 knockdown crabs. [ABSTRACT FROM AUTHOR]