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Regulatory O-GlcNAcylation sites on FoxO1 are yet to be identified

Yann Fardini1, Yobana Perez-Cervera2, Luc Camoin3

  • 1INSERM, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.

Biochemical and Biophysical Research Communications
|May 7, 2015
PubMed

Insights

Researchers investigated O-GlcNAcylation sites on the FoxO1 protein. Mutating known sites did not reduce FoxO1 activity, suggesting other regulatory sites remain undiscovered.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Post-translational Modifications

Background:

  • O-GlcNAcylation is a dynamic post-translational modification regulating protein function.
  • Previous studies identified four O-GlcNAcylation sites on human FOXO1, but their individual roles in activity were unclear.
  • The impact of mutating all known O-GlcNAcylation sites on FOXO1 activity was not previously assessed.

Purpose of the Study:

  • To investigate the functional significance of known O-GlcNAcylation sites in mouse Foxo1.
  • To identify novel O-GlcNAcylation sites on Foxo1.
  • To determine the effect of mutating identified O-GlcNAcylation sites on Foxo1's transcriptional activity.

Main Methods:

  • Site-directed mutagenesis of identified O-GlcNAcylation residues in mouse Foxo1.
  • Mass spectrometry (High-energy Collisional Dissociation) to identify O-GlcNAcylated peptides.
  • Assessment of O-GlcNAcylation status and transcriptional activity following mutagenesis.

Main Results:

  • Mutation of the four previously identified O-GlcNAcylation sites in mouse Foxo1 did not decrease, and potentially increased, its O-GlcNAcylation and transcriptional activity.
  • A novel O-GlcNAcylation site, T646, was identified on Foxo1.
  • Mutagenesis of T646, individually or combined with other sites, did not impair Foxo1 O-GlcNAcylation or transcriptional activity.

Conclusions:

  • The identified O-GlcNAcylation sites (T317, S550, T648, S654, and T646) are not solely responsible for regulating Foxo1 activity via O-GlcNAcylation.
  • Key regulatory sites controlling Foxo1 activity through O-GlcNAcylation remain to be identified.
  • Further research is needed to elucidate the complete O-GlcNAcylation-dependent regulatory network of Foxo1.
Keywords:
Forkhead transcription factor box OO-GlcNAc glycosylationO-GlcNAc transferasePost-translational modificationSite-directed mutagenesisTranscriptional activity

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