Syk regulates the haemocyte autophagy through inducing the mRNA expressions of autophagy-related genes and the cleavage of Cg LC3 in oyster antibacterial immunity

Hongsheng Yao; Jiejie Sun; Tong Zhang; Lingling Wang; Linsheng Song

doi:10.1016/j.fsirep.2023.100085

Syk regulates the haemocyte autophagy through inducing the mRNA expressions of autophagy-related genes and the cleavage of Cg LC3 in oyster antibacterial immunity

Fish Shellfish Immunol Rep. 2023 Jan 16:4:100085. doi: 10.1016/j.fsirep.2023.100085. eCollection 2023 Dec.

Authors

Hongsheng Yao^{1

2}, Jiejie Sun^{1

2}, Tong Zhang^{1

2}, Lingling Wang^{1

3

2

4}, Linsheng Song^{1

3

2}

Affiliations

¹ Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, 52 Heishijiao Street, Dalian 116023, China.
² Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
³ Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China.
⁴ Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China.

Abstract

Spleen tyrosine kinase (Syk) is reported to be involved in activating the autophagy. Recently, a homologue of Syk was identified from Pacific oyster Crassostrea gigas (defined as CgSyk). In the present study, the molecular characteristics of CgSyk and its regulation mechanism in autophagy were investigated in oyster C. gigas. The full-length cDNA of CgSyk was of 4566 bp with an open reading frame (ORF) of 1989 bp. CgSyk encoded a polypeptide of 662 amino acids, containing two Src homology 2 (SH2) domains and one tyrosine kinase catalytic (TyrKc) domain. The deduced amino acid sequence of CgSyk shared low similarity with the previously identified Syks from other species. In the phylogenetic tree, CgSyk was first clustered with Crassostrea virginica CvSyk, and then classified into a branch of invertebrate Syks. In CgSyk-RNAi oysters, the mRNA expressions of CgLC3, CgP62, CgBeclin-1 and CgATG5 in haemocytes decreased significantly at 12 h after Vibrio splendidus stimulation. At the same time, the abundance of CgLC3Ⅱ in haemocytes, and the autophagy rate of haemocytes in CgSyk-RNAi oysters decreased significantly at 12 h after V. splendidus stimulation. All the results collectively suggested that CgSyk regulated the autophagy through inducing the mRNA expressions of autophagy-related genes and the cleavage of CgLC3 to defend against bacterial invasion in oysters.

Keywords: Autophagy; Crassostrea gigas; Haemocytes; Spleen tyrosine kinase; Vibrio splendidus.