The basal transcription complex component TAF3 transduces changes in nuclear phosphoinositides into transcriptional output

The aim of the experiment was to determine if changes in nuclear phosphoinositides induced by depletion of PIP4K2B impacts on gene expression through a specific phosphoinositide interaction site on TAF3. TAF3 is a core promoter complex protein that contains a PHD finger that interacts with H3K4me3. We determined that The TAF3 PHD finger also interacted with phosphoinositides and generated mutants of TAF3 that were unable to interact with phosphoinositides but still were capable of interacting with H3K4me3. PIP4K2B depletion enhances C2C12 myoblast differentiation. We depleted the endogenous TAF3 from C2C12 myoblast cells and rescued the cells with either a wild type TAF3 or a mutant unable to interact with PI (KK-TAF3). These cells were then maintained as controls or depeleted of PIP4K2B. The cells were then differentiated for two days or were treated wtih a etoposide. We aimed to identify genes that were reguated by PIP4K2B that required an intact phosphoinositide binding site.

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