The Tip60 acetylome is a hallmark of the proliferative state in Drosophila

Abstract

The acetyltransferase KAT5/Tip60 is an epigenetic regulator of transcription and the DNA damage response. In Drosophila, Tip60 acetylates histones as part of the DOM-A complex, but it is unclear whether it has other substrates. In this work, we comprehensively studied the functions of Tip60 in a Drosophila proliferative cell model. Depletion of Tip60 arrests the cell cycle, but remaining viable cells resist mutagenic irradiation. The impaired proliferation is explained by reduced expression of critical cell cycle genes. Tip60 binds their transcription start sites and Tip60-dependent acetylation of the histone variant H2A.V correlates with transcription activity. A potentially synergistic pathway for cell cycle regulation involves the acetylation of proteins other than histones. The Tip60-dependent nuclear acetylome contains hundreds of proteins, many of which are involved in diverse aspects of cell growth and division, including replication, mitosis, gene expression, chromatin organization and ribosome biogenesis. We hypothesize that Tip60 coordinates the proliferative state through histone and non-histone effectors. Reversible acetylation of diverse effector proteins bears potential for fine-tuning energy-intensive processes in response to stresses or nutritional shortcomings. Our study portrays the DOM-A/TIP60 complex as a general promoter of cell proliferation.