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LIN-28 and the poly(U) polymerase PUP-2 regulate let-7 microRNA processing in Caenorhabditis elegans

Nicolas J Lehrbach1, Javier Armisen, Helen L Lightfoot

  • 1Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, The Henry Wellcome Building of Cancer and Developmental Biology, Cambridge, UK.

Nature Structural & Molecular Biology
|August 29, 2009
PubMed

Insights

LIN-28 and PUP-2 regulate let-7 microRNA (miRNA) processing in C. elegans. LIN-28 blocks let-7 activity by binding pre-miRNA, while PUP-2 stabilizes it, revealing a conserved regulatory switch.

Area of Science:

  • Molecular Biology
  • Developmental Biology
  • RNA Biology

Background:

  • let-7 microRNA (miRNA) is crucial for stem cell differentiation and development.
  • LIN-28 is implicated in regulating let-7, but its precise mechanism remains unclear.
  • let-7 functions as a tumor suppressor and is vital in stem cell biology.

Purpose of the Study:

  • To elucidate the roles of LIN-28 and PUP-2 in let-7 processing and regulation in Caenorhabditis elegans.
  • To investigate the interaction between LIN-28, PUP-2, and let-7 pre-miRNA.
  • To understand the conserved regulatory mechanisms of let-7.

Main Methods:

  • In vivo studies in Caenorhabditis elegans to assess LIN-28 function.
  • Biochemical assays to study the interaction between LIN-28, PUP-2, and let-7 pre-miRNA.
  • In vitro uridylation assays to examine PUP-2 activity.

Main Results:

  • LIN-28 is necessary and sufficient to inhibit let-7 activity by directly binding let-7 pre-miRNA and preventing Dicer processing.
  • PUP-2, a poly(U) polymerase, regulates the stability of LIN-28-bound let-7 pre-miRNA.
  • LIN-28 and PUP-2 interact directly, with LIN-28 stimulating PUP-2-mediated uridylation of let-7 pre-miRNA in vitro.

Conclusions:

  • LIN-28 and let-7 form an ancient regulatory switch conserved across species.
  • PUP-2 plays a key role in LIN-28-dependent let-7 regulation during development.
  • Poly(U) polymerases like PUP-2 may represent therapeutic targets for stem cell-related and cancerous conditions.

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