The Notch pathway in Metazoa: a comparative analysis across cnidarians and beyond

Area of Science:

• Evolutionary developmental biology
• Comparative genomics
• Cell signalling

Background:

• The Notch signalling pathway regulates key cellular processes in Metazoa.
• Its evolutionary history in early branching lineages like cnidarians and myxozoans is poorly understood.
• Parasitic myxozoans exhibit extreme genomic and morphological reduction.

Purpose of the Study:

• To investigate the presence and structural diversity of Notch pathway components in early diverging metazoans.
• To focus on Myxozoa and understand their Notch pathway evolution.
• To explore the phylogenetic relationships and structural variations of Notch components.

Main Methods:

• Comparative genomic analysis across 58 metazoan species.
• Phylogenetic analyses of Notch receptors and ligands (Delta, Jagged).
• Immunolocalization studies in Sphaerospora molnari.

Main Results:

• Core Notch components are broadly conserved but show losses in several early lineages.
• Myxozoa possess a reduced set of 14 out of 28 canonical components, lacking MAML, Hes/Hey, and DVL.
• Structural divergence in Notch receptors and early diversification of Delta ligands were observed.
• The Notch receptor is active in proliferative Sphaerospora molnari cells.

Conclusions:

• The Notch pathway has undergone significant evolutionary changes and reductions in early branching metazoans, particularly in Myxozoa.
• Structural variations in Notch components reflect lineage-specific adaptations.
• The conserved role of Notch signalling in development is evident across diverse early metazoan groups.