The pro-domain of the zebrafish Nodal-related protein Cyclops regulates its signaling activities

Area of Science:

• Molecular and Developmental Biology
• Cellular Signaling Pathways

Background:

• Nodal proteins, part of the transforming growth factor beta (TGFbeta) family, are crucial for embryonic development in vertebrates.
• Mutations in Nodal factors cause severe developmental issues, and elevated Nodal levels are linked to melanoma progression.
• The precise mechanisms by which Nodal pro-domains regulate protein activity remain largely unknown.

Purpose of the Study:

• To characterize the zebrafish Nodal-related factor Cyclops (Cyc) and elucidate the functions of its pro-domain.
• To investigate the molecular basis for Cyc's short-range signaling activities.
• To explore the role of Nodal pro-domain mutations in human diseases like congenital heterotaxia.

Main Methods:

• Characterization of the zebrafish Nodal-related factor Cyclops (Cyc).
• Identification and functional analysis of a lysosome-targeting region within the Cyc pro-domain.
• Analysis of a human NODAL (hNODAL) pro-domain mutation associated with congenital heterotaxia.

Main Results:

• A lysosome-targeting region in the Cyc pro-domain was identified, which destabilizes the precursor and restricts Cyc activity.
• Both pro- and mature-domains of Cyc were found to regulate its stability.
• A mutation in the human NODAL pro-domain linked to congenital heterotaxia was characterized, showing increased Nodal-response gene expression.

Conclusions:

• The Nodal pro-domain plays an unexpected role in regulating protein stability and activity through mechanisms like lysosomal targeting.
• This study reveals the molecular basis for Cyc's short-range signaling.
• The findings offer a potential mechanism for familial heterotaxia linked to NODAL mutations.