Interferon regulatory factor-7 is required for hair cell development during zebrafish embryogenesis

Area of Science:

• Developmental Biology
• Immunology
• Genetics

Background:

• Interferon regulatory factor-7 (IRF7) is a key regulator of immune responses.
• IRF7 is expressed in zebrafish embryonic otic vesicles, but its role in hair cell development is unknown.
• Investigating IRF7's function may reveal new insights into potential deafness genes.

Purpose of the Study:

• To investigate the role of IRF7 in the development of otic vesicle hair cells in zebrafish embryos.
• To determine if IRF7 functions as a potential deafness gene regulating hair cell development.

Main Methods:

• Whole-mount in situ hybridization (WISH) and morpholino-mediated gene knockdown of irf7 in zebrafish embryos.
• RNA sequencing to analyze gene expression changes upon irf7 downregulation.
• Rescue experiments using zebrafish irf7 mRNA and atp1b2b mRNA injection.

Main Results:

• Knockdown of irf7 led to severe developmental retardation, loss of neuromasts, and hair cell damage within 3 days post fertilization.
• Coinjection of irf7 mRNA partially rescued the observed defects, and atp1b2b mRNA injection also showed partial rescue.
• Hair cell loss in irf7 morphants was not due to apoptosis.
• RNA sequencing revealed significant upregulation (2053 genes) and downregulation (2678 genes) of gene expression, with 18 genes linked to hair cell or posterior lateral line development.

Conclusions:

• IRF7 plays an essential role in zebrafish hair cell development.
• The findings suggest that IRF7 may be a novel member of the deafness gene family.