Scube2 mediates Hedgehog signalling in the zebrafish embryo

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Hedgehog (HH) proteins are crucial morphogens guiding cell fate determination in embryonic development.
• Disruption of HH signaling in zebrafish mutants, termed 'you'-type, impairs the development of Hedgehog-sensitive muscle fates.

Purpose of the Study:

• To investigate the function of the zebrafish 'you' mutant, identifying its genetic basis and role in HH signaling.
• To elucidate the molecular mechanism by which Scube2 influences HH signal transduction.

Main Methods:

• Phenotypic analysis of zebrafish mutants.
• Molecular characterization, including gene identification and sequence analysis.
• Epistatic and homology analyses to determine Scube2's position in the HH pathway.

Main Results:

• The 'you' mutant results from mutations in the zebrafish orthologue of mammalian scube2.
• Scube2 functions upstream of Smoothened (Smoh) in the HH signal transduction pathway.
• Scube2 exhibits homology to cubilin, suggesting a role in protein trafficking and HH signal reception.

Conclusions:

• Zebrafish Scube2 is essential for proper HH signal transduction during embryonic development.
• Scube2 likely acts at or before the plasma membrane, potentially mediating HH signal reception.
• The findings provide insights into the upstream regulation of the HH pathway and potential roles in protein trafficking.