Sequence and expression analysis of the cytoplasmic pattern recognition receptor melanoma differentiation-associated gene 5 from the barbel chub Squaliobarbus curriculus.

Abstract

MDA5 is a cytoplasmic viral double-stranded RNA recognition receptor that plays a pivotal role in the aquatic animal innate immune system. To decipher the role of MDA5 of Squaliobarbus curriculus (ScMDA5) in the immune response, full-length cDNA of ScMDA5 was cloned using the RACE technology, mRNA and protein expression levels of ScMDA5 signalling pathway members in response to stimulation were detected and effects of overexpression of ScMDA5 on the immune response were investigated. ScMDA5 comprises 3597 bp and is composed of an open reading frame (2958 nucleotides long) that translates into a putative peptide of 985 amino acid residues. ScMDA5 possesses two N-terminal caspase-recruiting domains, DEAD-like helicases superfamily, helicase superfamily C-terminal and RIG-I_C-RD domains, and differences in these domains among species were mainly observed with respect to their length and location. ScMDA5 was closely clustered with those of Carassius auratus, Ctenopharyngodon idellus and Mylopharyngodon piceus. ScMDA5 transcripts were most abundant in the spleen and the lowest in the liver. Expression levels of ScMDA5 in healthy tissues were significantly correlated with those of ScIRF3, ScIRF7 and ScIFN. Besides, mRNA expression levels of ScIRF3 were significantly correlated with those of ScIRF7 (0.956, P < 0.01). Expression level changes, including downregulation, upregulation and initial upregulation followed by downregulation, were found in ScMDA5 signalling pathway molecules in tissues after grass carp reovirus infection. Protein levels of ScMDA5 were the highest in the liver and the lowest in the spleen in detected healthy tissues. Overexpression of ScMDA5 led to significantly enhanced CiIRF7 and CiMx transcription in grass carp ovary cells (P < 0.05). The results of this study helped to clarify the role of ScMDA5 in the immune reaction against grass carp reovirus and provided fundamental information for fish breeding to achieve strong resistance to infection.

• Authors: Yaoguo Li, Shengzhen Jin, Xin Zhao, Hong Luo, Rui Li, Dongfang Li, Tiaoyi Xiao
• Journal: Fish & shellfish immunology (Fish Shellfish Immunol) Vol. 94 Pg. 485-496 (Nov 2019) ISSN: 1095-9947 [Electronic] England
• PMID: 31494278 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 Elsevier Ltd. All rights reserved.

Chemical References

• Fish Proteins
• Interferon-Induced Helicase, IFIH1

Topics

• Amino Acid Sequence
• Animals
• Base Sequence
• Cyprinidae (genetics, immunology)
• Fish Diseases (immunology)
• Fish Proteins (chemistry, genetics, immunology)
• Gene Expression Profiling (veterinary)
• Gene Expression Regulation (immunology)
• Immunity, Innate (genetics)
• Interferon-Induced Helicase, IFIH1 (chemistry, genetics, immunology)
• Phylogeny
• Reoviridae (physiology)
• Reoviridae Infections (immunology, veterinary)
• Sequence Alignment (veterinary)