The lysine acetyltransferase MOF: its interactome, role in breast cancer, and characterisation of a novel isoform

Abstract

Males absent on the first (MOF), also known as hMOF, MYST1, or KAT8, is a lysine acetyltransferase responsible for bulk acetylation of Histone H4 at lysine 16 (H4K16ac), though it has also been shown to acetylate several non-histone targets such as p53. MOF and its associated acetyltransferase activity has many roles within the cell, including activation of transcription, chromatin remodelling, mediating the DNA damage response, induction of apoptosis, and the maintenance of pluripotency in embryonic stem cells. Both MOF and H4K16ac have been repeatedly reported at reduced levels in cancer, and this loss has been correlated with a poorer disease prognosis. To further investigate the role of MOF both in the normal cell and in cancer cell transformation, a monoclonal antibody against MOF was generated in the lab. This led to the discovery of a novel MOF splice variant which does not contain the enzymatic domain and is catalytically inactive. This isoform appears to have a dominant negative effect on H4K16ac over full-length MOF. Knockout of MOF in cells by CRISPR/Cas9-mediated targeting produced a surprising result when robust H4K16ac was maintained in cells lacking MOF, contrary to all previous publications, in which generated MOF-null cells and animals led to a concurrent loss of H4K16ac. Knockout of MOF did however lead to increasing genomic instability, decreased cell adhesion, disordered growth, and perturbed e-cadherin localisation, suggesting that cells may gain a higher metastatic potential upon loss of MOF. Finally, a novel proximity biotinylation method known as BioID was employed to identify novel MOF interactors under a number of conditions. A diverse dataset was generated containing both known MOF interactors and potential novel interactors, as well as suggesting novel functions for MOF in the cell based on gene ontology analysis. Together, these results show the diversity in function of MOF within the cell and suggest a role for MOF in cancer progression.