Sexually dimorphic Argonaute localization underlies sex-specificity of small RNA pathways during germ cell development

Meiosis, a specialized form of cell division that produces haploid gametes, requires precise gene regulation to mediate proper germ cell development. Utilized during both oogenesis and spermatogenesis, small RNA pathways tune expression during germ cell development using functional Argonaute (AGO) proteins. AGOs mediate gene expression by both licensing genes required for meiosis and epigenetic inheritance, while simultaneously silencing deleterious genomic elements. The function and localization of AGOs during C. elegans oogenesis has been extensively characterized but less is known about mechanisms of AGO-mediated gene regulation during spermatogenesis, and if they differ from egg development. Here, I demonstrate that the cytoplasmic Argonaute proteins, WAGO-1 and WAGO-4, are sexually dimorphic in their localization throughout egg and sperm development, and that function of WAGO-1 protein structural features affects sex-specific gene regulation during C. elegans germ cell development. Using a whole germline image analysis pipeline, I characterize the morphology of WAGO-1 and WAGO-4 foci, as well as co-localization with germ granule components PGL-1 and ZNFX-1, through all stages of meiotic prophase I. These analyses highlight the highly dynamic properties of AGOs, and how these biophysical attributes differ between oogenesis and spermatogenesis at distinct stages of germ cell development. I further reveal that native WAGO-1 and WAGO-4 structures are required for sex-specific maintenance of germ granule structure during oogenesis and spermatogenesis. Finally, I link WAGO-1-mediated disruption of germ granule structure to sex-specific regulation of mRNA expression and small RNA profiles. Overall, these data highlight that sexual dimorphism in WAGO-1and WAGO-4 structure are imperative for mediating germ granule structure, and mutations to WAGO-1 disrupt not only the germ granule, but also gene regulation in a sexually dimorphic manner. Taken together my thesis work provides a foundation for our understanding of sex-specific roles of conserved Argonaute proteins in properly regulating gene expression and maintaining germ granule structure during oogenesis and spermatogenesis.This dissertation includes previously unpublished co-authored material.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Department of Biology

Grantor dc:publisher

University of Oregon

Year dc:date.issued

2025

Author dc:creator

• DiNardo, Acadia

Advisor dc:contributor.advisor

• Libuda, Diana

• Germ Cells
• RNA

Statement dc:rights

• All Rights Reserved.

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/1794/31502

OAI record oai:identifier

https://scholarsbank.uoregon.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Ascholarsbank.uoregon.edu%3A1794%2F31502