Grouper (Epinephelus coioides) MyD88 adaptor-like (Mal): Molecular cloning, expression, and functionality

Area of Science:

• Immunology
• Marine Biology
• Genetics

Background:

• Innate immunity relies on pathogen recognition receptors (PRRs) like Toll-like receptors (TLRs) to detect pathogen-associated molecular patterns (PAMPs).
• MyD88 adaptor-like (Mal) acts as a crucial adaptor protein, bridging TLRs to downstream signaling molecules like MyD88.

Purpose of the Study:

• To identify and characterize the Mal gene in orange-spotted grouper (Epinephelus coioides).
• To investigate the expression patterns and functional role of EcMal in the grouper immune response.

Main Methods:

• Gene cloning and sequencing to identify the EcMal open reading frame and genomic structure.
• Quantitative real-time PCR (qRT-PCR) to analyze EcMal expression in various tissues and after pathogen challenge.
• Subcellular localization studies and NF-κB activation assays in grouper spleen cells.

Main Results:

• The EcMal gene was cloned, consisting of 831 bp encoding 276 amino acids, with a genomic structure of three exons and two introns.
• EcMal showed conserved sequence identity with Mal from other species and was ubiquitously expressed in healthy grouper, with highest levels in the head kidney.
• EcMal expression was significantly upregulated in the gill and spleen following Cryptocaryon irritans infection.
• EcMal localized to both the cytoplasm and nucleus and demonstrably activated NF-κB signaling in grouper spleen cells.

Conclusions:

• EcMal is a key component of the innate immune system in orange-spotted grouper.
• EcMal plays a significant role in the immune response to Cryptocaryon irritans infection.
• EcMal functions in immune signaling pathways, including NF-κB activation, contributing to fish disease resistance.