Loss of Atoh8 Affects Neurocranial and Axial Skeleton Development in Zebrafish

Area of Science:

• Developmental Biology
• Genetics
• Skeletal Biology

Background:

• The transcription factor atonal homologue 8 (Atoh8) is involved in various developmental processes across species.
• Its precise role in zebrafish skeletal development remains unclear, with conflicting results from previous studies.
• Mammalian studies suggest Atoh8 influences skeletal size.

Purpose of the Study:

• To investigate the phenotypic effects of Atoh8 disruption on zebrafish skeletogenesis using a CRISPR/Cas9-generated mutant.
• To analyze the expression pattern of Atoh8 in wildtype zebrafish during skeletal development.

Main Methods:

• Generated a CRISPR/Cas9-mediated permanent knockout of the Atoh8 gene in zebrafish.
• Conducted detailed morphometric analysis of craniofacial and axial skeletal elements at 12 days post-fertilization.
• Examined Atoh8 gene expression patterns in wildtype zebrafish.

Main Results:

• Homozygous Atoh8 mutant zebrafish are viable and display no overt morphological defects.
• Despite Atoh8 expression in skeletal structures, morphometric analysis revealed only subtle effects.
• Orbital cartilage formation and chordacentra mineralization were negatively impacted by Atoh8 loss.

Conclusions:

• Atoh8 is involved in zebrafish skeletal development, albeit with subtle phenotypic consequences.
• Mild effects may be due to compensatory mechanisms, such as nonsense-mediated mRNA decay.
• Atoh8's role is critical at developmental interfaces involving multiple cell lineages for bone and cartilage formation.