O-GlcNAcylation of FOXK1 orchestrates the E2F pathway

ABSTRACT: Gene transcription is a highly regulated process, and deregulation of transcription factors activity underlie numerous pathologies including cancer. FOXK1 and FOXK2 (FOXK1/2) transcription factors have recently emerged as important regulators of cell metabolism, autophagy and cell differentiation. While FOXK1/2 possesses many overlapping functions in normal biology, their specific functions as well as deregulation of their transcriptional activity in cancer is less clear and often contradictory. FOXK1, but less FOXK2, is known to have oncogenic properties as higher expression levels of FOXK1 has been observed in several cancers and is correlated with tumor progression, invasion, and metastasis. However, the molecular mechanism by which FOXK1 exert its oncogenic properties in caner remains unknown. Here we show that elevated expression of FOXK1, but not FOXK2, in normal human fibroblasts promotes transcription of E2F target genes associated with increased proliferation and delayed senescence entry. Fibroblasts overexpressing FOXK1 are also more prone to cellular transformation with minimal oncogenic combinations, suggesting important oncogenic proprieties of FOXK1. Mechanistically, we found that FOXK1, but not FOXK2, is specifically modified by O-GlcNAcylation. FOXK1 O-GlcNAcylation is modulated during the cell cycle and its highest levels coincides with the G1/S phase transition. Moreover, FOXK1 O-GlcNAcylation is increased following cell transformation and loss of this modification leads to decreased FOXK1 ability to promote cellular transformation and tumor growth. Cells overexpressing FOXK1 O-GlcNAcylation-defective mutants have lower E2F1 expression, cell proliferation, and tumour growth. Our results define a distinct role of FOXK1 via O-GlcNAcylation in controlling the cell cycle through the orchestration of the E2F pathway.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Eric Bonneil  

LAB HEAD: Bachir El Affar

PROVIDER: PXD050014 | Pride | 2024-06-10

REPOSITORIES: Pride