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Lost and Found: Piwi and Argonaute Pathways in Flatworms
Santiago Fontenla1, Gabriel Rinaldi2, Jose F Tort1
1Departamento de Genética, Facultad de Medicina, Universidad de la República (UDELAR), Montevideo, Uruguay.
Frontiers in Cellular and Infection Microbiology
|June 14, 2021
Summary
Parasitic flatworms lost Piwi RNA pathways but gained unique Argonautes, suggesting adaptations for parasitism. Free-living flatworms retain complete small RNA pathways, including Piwi proteins and a novel Fliwi Argonaute.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Genomics
Background:
- Platyhelminthes (flatworms) are highly successful parasites.
- Small non-coding RNAs regulate development in parasitic species.
- Parasitic flatworms exhibit unique Argonaute gene profiles.
Purpose of the Study:
- Compare small RNA pathways in free-living ('turbellarians') and parasitic (Neodermata) flatworms.
- Investigate evolutionary adaptations during the transition to parasitism.
- Analyze conservation and diversification of Argonaute gene families.
Main Methods:
- Comparative genomic analysis of small RNA pathway components.
- Identification and characterization of Argonaute gene families (Piwi, canonical, FL-Ago).
- Sequence conservation and functional residue analysis.
Main Results:
- Free-living flatworms possess complete miRNA and RNAi pathways, including Piwi proteins and a unique 'Fliwi' Argonaute.
- Parasitic Neodermata lack Piwi proteins but show expansion of a flatworm-specific Argonaute (FL-Ago) clade.
- FL-Agos exhibit high evolutionary rates but conserved functional residues, suggesting specialized roles.
Conclusions:
- Significant divergence in small RNA pathways between free-living and parasitic flatworms.
- Loss of Piwi pathways and gain/expansion of FL-Agos may be key adaptations to parasitism in Neodermata.
- Argonaute gene family evolution in Platyhelminthes reveals unique diversification linked to parasitic lifestyle.
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