Sea Anemone Membrane Attack Complex/Perforin Superfamily Demonstrates an Evolutionary Transitional State between...

Area of Science:

• Evolutionary biology
• Genomics
• Molecular biology

Background:

• Gene duplication is a key driver of evolutionary innovation, particularly in the generation of animal toxins.
• The recruitment of toxins into venom systems is well-documented, but the reverse process remains less understood.

Purpose of the Study:

• To investigate the evolutionary history and functional roles of the Membrane Attack Complex and Perforin Family (MAC) in cnidarians.
• To provide evidence for the reverse recruitment of toxins from venom to nonvenomous cellular functions.

Main Methods:

• Comparative genomics was used to analyze MAC gene families across various cnidarian species.
• The model sea anemone Nematostella vectensis was used for in-depth investigation of MAC paralogs.
• Gene knockdown experiments were performed to assess the function of endomesodermally expressed MACs.

Main Results:

• Members of the MAC family were found to be recruited into cnidocytes (venom-injecting cells) in corals and sea anemones, suggesting an ancestral role as toxins.
• Three MAC members in Nematostella vectensis underwent lineage-specific duplications and were reverse-recruited into endomesodermal cells.
• Knockdown of these endomesodermal MAC paralogs resulted in developmental abnormalities, indicating essential nonvenomous functions.

Conclusions:

• The study provides the first evidence for reverse recruitment of toxins from venom to organismal development.
• The ancestral MAC protein likely functioned as a cnidocyte-expressed toxin before its recruitment into nonvenomous developmental pathways.
• This research sheds light on the dynamic evolutionary interplay between venom systems and fundamental biological processes.