The Ahr2-Dependent wfikkn1 Gene Influences Zebrafish Transcriptome, Proteome, and Behavior

Area of Science:

• Developmental Biology
• Molecular Toxicology
• Genomics

Background:

• The aryl hydrocarbon receptor (AHR) pathway is vital for vertebrate development and is activated by environmental toxicants like PAHs and TCDD.
• While AHR activation mechanisms are understood, downstream signaling events remain largely unexplored.
• Previous transcriptomics identified wfikkn1 as coexpressed with cyp1a, a marker for AHR activation, in zebrafish exposed to PAHs and TCDD.

Purpose of the Study:

• To investigate the role of wfikkn1 in AHR signaling and its impact on zebrafish development and gene expression.
• To functionally characterize wfikkn1 using CRISPR-Cas9 gene editing.
• To assess the involvement of wfikkn1 in TCDD-induced toxicity and behavioral changes.

Main Methods:

• Generated a CRISPR-Cas9 wfikkn1 mutant zebrafish line.
• Exposed wildtype and mutant zebrafish to dimethyl sulfoxide (control) or TCDD.
• Utilized 48-hpf mRNA sequencing and mass spectrometry-based proteomics to analyze transcriptomic and proteomic changes.
• Assessed morphological and behavioral phenotypes across all life stages.

Main Results:

• wfikkn1 expression was dependent on Ahr2 in TCDD-exposed zebrafish.
• Over 700 differentially expressed genes and 325 differentially expressed proteins were identified in wfikkn1 mutants.
• Functional enrichment analysis indicated wfikkn1 involvement in skeletal muscle development and neurological pathways.
• Mutant zebrafish exhibited behavioral deficiencies, but wfikkn1 absence did not significantly alter TCDD-induced behavioral effects.

Conclusions:

• wfikkn1 plays a significant role in altering the transcriptome and proteome in developing zebrafish.
• wfikkn1 is involved in skeletal muscle and neurological pathways.
• wfikkn1 is likely a necessary functional component of the AHR signaling cascade.
• wfikkn1 does not appear to be significantly involved in TCDD's overt toxicity.