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bioRxiv · 10.1101/2023.02.15.528708

Functional significance of PUF partnerships in C. elegans germline stem cells

Ferdous, A. S.·Costa Dos Santos, S. J.·Kanzler, C. R.·Shin, H.·Carrick, B. H.·Crittenden, S. L.·Wickens, M.·Kimble, J.
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Abstract

PUF RNA-binding proteins are conserved stem cell regulators. Four PUF proteins govern self-renewal of C. elegans germline stem cells together with two intrinsically disordered proteins, LST-1 and SYGL-1. Based on yeast two-hybrid results, we proposed a composite self-renewal hub in the stem cell regulatory network, with eight PUF partnerships and extensive redundancy. Here, we investigate LST-1-PUF and SYGL-1-PUF partnerships and their molecular activities in their natural context - nematode stem cells. We confirm LST-1-PUF partnerships and their specificity to self-renewal PUFs by co-immunoprecipitation and show that an LST-1(AmBm) mutant defective for PUF-interacting motifs does not complex with PUFs in nematodes. LST-1(AmBm) is used to explore the functional significance of the LST-1-PUF partnership. Tethered LST-1 requires the partnership to repress expression of a reporter RNA, and LST-1 requires the partnership to co-immunoprecipitate with NTL-1/Not1 of the CCR4-NOT complex. We suggest that the partnership provides multiple molecular interactions that work together to form an effector complex on PUF target RNAs. Comparison of PUF-LST-1 and Pumilio-Nanos reveals fundamental molecular differences, making PUF-LST-1 a distinct paradigm for PUF partnerships. Summary statementPartnerships between PUF RNA-binding proteins and intrinsically disordered proteins are essential for stem cell maintenance and RNA repression.

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Ferdous, A. S., Costa Dos Santos, S. J., Kanzler, C. R., Shin, H., Carrick, B. H., Crittenden, S. L., Wickens, M., Kimble, J.. 2023-02-16. Functional significance of PUF partnerships in C. elegans germline stem cells. https://doi.org/10.1101/2023.02.15.528708

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