Grass carp MAP3K4 participates in the intestinal immune response to bacterial challenge

Fufa Qu; Jialing Li; Xuan Zeng; Qing She; Yurong Li; Wenjie Xie; Shenping Cao; Yonghua Zhou; Zhimin He; Jianzhou Tang; Zhuangwen Mao; Yuping Wang; Jiamei Fang; Wenqian Xu; Zhen Liu

doi:10.1016/j.fsi.2021.11.016

Grass carp MAP3K4 participates in the intestinal immune response to bacterial challenge

Fish Shellfish Immunol. 2022 Jan:120:82-91. doi: 10.1016/j.fsi.2021.11.016. Epub 2021 Nov 13.

Authors

Fufa Qu¹, Jialing Li¹, Xuan Zeng¹, Qing She¹, Yurong Li¹, Wenjie Xie¹, Shenping Cao¹, Yonghua Zhou¹, Zhimin He¹, Jianzhou Tang¹, Zhuangwen Mao¹, Yuping Wang¹, Jiamei Fang¹, Wenqian Xu¹, Zhen Liu²

Affiliations

¹ Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha 410022, China.
² Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha 410022, China. Electronic address: 25300085@qq.com.

PMID: 34780976
DOI: 10.1016/j.fsi.2021.11.016

Abstract

Mitogen-activated protein kinase kinase kinase 4 (MAP3K4) is a multifunctional mediator of the conserved MAPK signaling pathway that plays essential roles in the regulation of immune responses in mammals. However, the function of teleost MAP3K4s in innate immunity, especially in the intestinal immune system, is still poorly understood. In the current study, we identified a fish MAP3K4 homolog (CiMAP3K4) in Ctenopharyngodon idella as well as its immune function in intestine following bacterial infection in vivo and in vitro. The open reading frame (ORF) of CiMAP3K4 encodes putative peptide of 1544 amino acids containing a predicted serine/threonine protein kinase (S_TKc) domain with high identity with other fish MAP3K4s. Phylogenetic analysis revealed the CiMAP3K4 belonged to the fish cluster and showed the closest relationship to Pimephales promelas. Quantitative real-time PCR (qRT-PCR) analysis revealed that CiMAP3K4 transcripts were widely distributed in all tested tissues, especially with high expression in the muscle and intestine of healthy grass carp. In vitro, CiMAP3K4 gene expression was upregulated by bacterial PAMPs (lipolysaccharide (LPS), peptidoglycan (PGN), L-Ala-γ-D-Glu-meso-diaminopimelic acid (Tri-DAP) and muramyl dipeptide (MDP)) and pathogens (Aeromonas hydrophila and Aeromonas veronii) in primary intestinal cells. In vivo, the mRNA expression levels of CiMAP3K4 in the intestine were significantly induced by bacterial MDP challenge in a time-dependent manner; however, this effect could be inhibited by the bioactive dipeptides β-alanyl-l-histidine (carnosine) and alanyl-glutamine (Ala-Gln). Moreover, CiMAP3K4 was located primarily in the cytoplasm, and its overexpression increased the transcriptional activity of AP-1 in HEK293T cells. Collectively, these results suggested that CiMAP3K4 might play an important role in the intestinal immune response to bacterial infections, which paves the way for a better understanding of the intestinal immune system of grass carp.

Keywords: Bacterial challenge; Grass carp; Intestinal immunity; MAP3K4; Molecular characteristics.

MeSH terms

Aeromonas hydrophila
Animals
Carps* / genetics
Carps* / immunology
Fish Diseases* / immunology
Fish Diseases* / microbiology
Fish Proteins* / genetics
Gram-Negative Bacterial Infections* / immunology
Gram-Negative Bacterial Infections* / veterinary
HEK293 Cells
Humans
Immunity, Innate / genetics
Intestines / immunology
Intestines / microbiology
MAP Kinase Kinase Kinase 4* / genetics
Phylogeny

Substances

Fish Proteins
MAP Kinase Kinase Kinase 4