Skip to main content
ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #430654
Research Project: Improving the Efficiency of Salmonid Aquaculture

Location: Cool and Cold Water Aquaculture Research

Title: Transcriptomic response to loss of functional IGFBP-2b in rainbow trout

Author
item Cleveland, Beth
item Radler, Lisa
item MUNETAKA, SHIMIZU - Hokkaido University

Submitted to: Physiological Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Insulin-like growth factor (IGF)-1 is an anabolic hormone that circulates in blood and promotes growth of muscle and bone tissue. Insulin-like growth factor binding proteins (IGFBP) regulate IGF signaling, but IGFBP-specific functions are not well characterized in fish. Scientists developed a line of rainbow trout without the IGFBP-2b protein, which transports IGF-1 in the bloodstream. The absence of the protein increased appetite and enhanced muscle growth by increasing IGF-1 signaling, while also influencing liver processes related to fats, sugars, and immune responses through different mechanisms. This study provides valuable insights that could inform strategies for improving growth rates in farmed fish populations.

Technical Abstract: In teleosts, insulin-like growth factor binding protein-2b (IGFBP-2b) is the major carrier of serum insulin-like growth factor (IGF). A line of gene edited rainbow trout (2bKO) was produced that lack a functional IGFBP-2b and associated phenotypes of reduced serum IGF-1, increased appetite, and faster growth compared to wild type controls (WT). Transcriptomic analysis was completed in liver and muscle from fed and feed deprived fish from the 2bKO and WT line; the DEG profiles were used to identify biological functions and pathways affected by the loss of IGFBP-2b and predict IGF-dependent and IGF-independent mechanisms regulated by IGFBP-2b. In general, DEGs reflected down-regulation of hepatic functions and signaling pathways in 2bkO liver, while an overall up-regulation was observed in muscle. A predicted increase in IGF-1 signaling in muscle of fed fish likely facilitated an up-regulation in myogenic mechanisms. IGF-independent responses in both liver and muscle are consistent with IGFBP-2b interacting with Type II nuclear receptors such as HNF4A, PPARG, LXR, and PXR, thus mediating changes in lipid, glucose, and sterol metabolism. In liver, immune and cytokine systems were inhibited (TNF-a, NF-kB, IL-1B), supporting that IGFBP-2b plays a central role in regulating the crosstalk between systems that modulate the balance of energy between growth and immune function. In summary, loss of IGFBP-2b increased muscle growth, likely through enhanced IGF-1 signaling, while modulations in nutrient metabolism and cytokine signaling appear to be mediated by IGF-independent mechanisms, providing insight into the functional role of IGFBP-2b in rainbow trout.