Multiple gene and transcript variants encoding trout C-polysaccharide binding proteins are differentially but...

Area of Science:

• Immunology
• Molecular Biology
• Aquaculture

Background:

• Two trout C-polysaccharide-binding proteins (TCBP1 and TCBP2) are implicated in early inflammatory responses.
• The specific functions and molecular characteristics of these proteins, particularly TCBP1, remain largely unelucidated.

Purpose of the Study:

• To characterize the cDNA sequences and transcript variants of TCBP1 and TCBP2 in rainbow trout (Oncorhynchus mykiss).
• To investigate the expression patterns of TCBP1 and TCBP2 in different tissues and under bacterial infection.
• To explore the cellular function of TCBP1, specifically its role in NF-κB signaling and apoptosis.

Main Methods:

• cDNA sequencing and analysis of TCBP1 and TCBP2 in rainbow trout.
• Identification and characterization of multiple TCBP1 mRNA transcript variants.
• Quantitative expression profiling of TCBP1 and TCBP2 mRNA in liver, spleen, and head kidney tissues.
• Green fluorescent protein (GFP) tagging and overexpression studies in HEK-293 cells to visualize TCBP1 function.

Main Results:

• Multiple TCBP1 transcript variants were identified, generated through alternative splicing or exon exclusion, with varying protein-coding potential.
• TCBP2 mRNA was found at higher concentrations than all TCBP1 isoforms combined in healthy trout tissues.
• Hepatic TCBP1 levels significantly increased upon Aeromonas salmonicida infection, while TCBP2 levels showed a moderate rise.
• Overexpression of TCBP1 in HEK-293 cells led to increased active NF-κB factors and induced cell death, suggesting a role in apoptosis.

Conclusions:

• Distinct evolutionary paths and protein domains separate TCBP1 and TCBP2.
• TCBP1 variants exhibit differential expression in response to bacterial infection, implicating them in the trout immune response.
• TCBP1 plays a role in proapoptotic NF-κB-dependent signaling pathways, contributing to cellular defense mechanisms.