Deiodinase knockdown affects zebrafish eye development at the level of gene expression, morphology and function

Area of Science:

• Developmental Biology
• Endocrinology
• Neuroscience

Background:

• Thyroid hormones (THs) are essential for vertebrate retinal development.
• Local TH availability is regulated by deiodinases (Ds).

Purpose of the Study:

• To investigate the roles of deiodinases in zebrafish eye development using morpholino technology.
• To elucidate the specific functions of TH-activating and -inactivating Ds in retinal development.

Main Methods:

• Morpholino-induced knockdown of deiodinases (D1, D2, and D3b) in zebrafish.
• Transcriptome analysis at 3 days post fertilization (dpf).
• Morphological assessment of eye development from 1 to 7 dpf.
• Functional visual assessment at 4 and 5 dpf.

Main Results:

• Knockdown of T4-activating Ds (D1D2MO) or T3-inactivating D3b (D3bMO) significantly impacted phototransduction and retinoid recycling.
• Morphological defects included reduced eye size, disrupted retinal lamination, and reduced rod and cone photoreceptor populations.
• D3-deficient zebrafish exhibited more prominent and persistent defects, along with disrupted visual function and light sensitivity.

Conclusions:

• Deiodinases are critical for normal zebrafish eye development.
• D3b, a T3-inactivating deiodinase, plays a central role in regulating retinal development and visual function.