Molecular Cloning and Expression Profiling of a c‐Jun N‐Terminal Kinase ( TmJNK ) in Response to Microbial Challenge in Tenebrio molitor

Abstract

Insects exclusively utilize their innate immunity to combat various types of microbial infections. As a part of conserved signaling pathways of innate immunity, the c‐Jun N‐terminal kinase (JNK) signaling pathway is engaged in the regulation of various stresses, development, and immunity. However, the roles of JNK signaling pathway in Tenebrio molitor remain unclear. Therefore, the objective of the present study was to clone, characterize, and analyze the expression pattern of TmJNK gene in T. molitor . The bioinformatics analyses showed that the protein encoded by the TmJNK gene consists of 390 amino acids and contains one conserved catalytic domain of serine/threonine kinase. The TmJNK gene was expressed throughout all developmental stages, with the highest expression levels in egg stage. Tissue‐specific expression analyses showed that TmJNK was highly expressed in hemocytes from young larvae and adults and increased in the gut from late larvae stage. In order to investigate its expression in immune response, the expression pattern of TmJNK was analyzed after the infection with three types of microorganisms, namely, Gram‐negative, Gram‐positive bacteria, and fungi. The results demonstrated that the expression pattern of TmJNK was tissue‐specific and time dependent and that the kinase was induced in the gut, integument, hemocytes, fat body, and Malpighian tubules at different time points. These data indicated that TmJNK is an important conserved signaling molecule that may be involved in stress signals and innate immunity in T. molitor .