O-GlcNAc transferase fine-tunes MYC-dependent transcription to promote cell cycle [RNA-seq]

O-GlcNAc transferase (OGT) is overexpressed in aggressive prostate cancer. Here, we employed ChIP-seq to map chromatin-bound O-GlcNAc loci in prostate cancer cells and discovered that these overlap with sites of active transcription and MYC binding. Using RNA-seq, we show that inhibition of OGT promotes MYC-dependent transcriptional repression of mRNAs involved in G1-S transition. O-GlcNAc ChIP-seq regions are highly enriched to transcription start sites and identify the ‘GFY’-motif. Proteins binding to this motif have not been established and we use synthetic oligonucleotides as a bait to enrich protein complexes associated with this sequence. By comparing the unbiased proteomic data from oligonucleotide enrichment with proteomic data from O-GlcNAc and MYC ChIP-mass spectrometry, we identified host cell factor 1 (HCF-1) as an interaction partner of MYC. Inhibition of OGT disrupted the interaction between MYC and HCF-1, and compromised MYC’s ability to promote proliferation of prostate cancer cells in the absence of androgens. Reverse phase protein arrays identified a set of proteins involved in mitosis that are dependent on MYC and OGT activity for expression. In conclusion, we show that OGT activity regulates MYC-driven proliferation by coordinating transcription and translation of cell cycle genes. two biological replicates for prostate cancer cell line (LNCaP) overexpressing MYC gene under the control of Doxycycline. Differential expressed genes were retreaved for these cells treated for 4 and 24 hours with Doxycycline, OSMI2 (a OGT inhibitor), or a cmbination of both (combo) versus the vehicle treated cells (DMSO)