The in vivo functional significance of PUF hub partnerships in C. elegans germline stem cells

Development. 2023 May 1;150(9):dev201705. doi: 10.1242/dev.201705. Epub 2023 May 9.

Abstract

PUF RNA-binding proteins are conserved stem cell regulators. Four PUF proteins govern self-renewal of Caenorhabditis elegans germline stem cells together with two intrinsically disordered proteins, LST-1 and SYGL-1. Based on yeast two-hybrid results, we previously 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 in vivo functional significance of the LST-1-PUF partnership. Tethered LST-1 requires this 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 in vivo. Comparison of LST-1-PUF and Nanos-Pumilio reveals fundamental molecular differences, making LST-1-PUF a distinct paradigm for PUF partnerships.

Keywords: CNOT complex; Intrinsically disordered proteins; Network hub; RNA repression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Caenorhabditis elegans Proteins* / genetics
  • Caenorhabditis elegans Proteins* / metabolism
  • Caenorhabditis elegans* / genetics
  • Caenorhabditis elegans* / metabolism
  • Germ Cells / metabolism
  • RNA / metabolism
  • Stem Cells / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • RNA
  • LST-1 protein, C elegans