Unravelling the role of TIP60 PXR complex in wound healing phenomenon and investigating the effect of post translational modifications affecting the intracellular dynamics and function of TIP60

Abstract

Chromatin modifiers are epigenetic enzymes that regulate gene expression by catalyzing the incorporation and removal of different chemical modifications on the chromatin. Lysine acetyltransferases are one such chromatin modifiers that catalyzes the transfer of acetyl group on lysine residues of targeted proteins. TIP60 is a member of the MYST (Moz, ybf2/Sas3, Sas2, Tip60) family of histone acetyltransferases that acetylates both histones and non-histone proteins and plays a major role in DNA damage repair, apoptosis, autophagy and cancer. TIP60 is also emerging as a nuclear receptor coregulator and has recently been shown to acetylate a class II nuclear receptor PXR (master regulator of xenobiotic metabolism) by which it modulates its intranuclear reorganization and together this complex of TIP60-PXR can promote migration and adhesion properties of the cell. In this study, we have demonstrated that the TIP60-PXR complex during wound-generated condition stimulates rapid filopodia formation which leads to enhanced cell migration, resulting in rapid wound closure. The qPCR analysis further revealed TIP60-PXR mediated increase in the expression of ROCK1 and Cdc42 transcripts, during wound-generated condition which play a crucial role in actin reorganization and filopodia formation. Also, we demonstrated that TIP60-PXR complex binds on the promoter region of ROCK1 gene and this complex can specifically acetylate H2B and H4 histones during wounded condition. Further, we also identified that autoacetylation mediated post-translational modification of TIP60 is necessary for its nuclear localization and phase separation and this phase separation of TIP60 is critical for its functions. In addition, we have identified few novel phosphorylation sites on TIP60 and could demonstrate that mutation of these putative phosphorylation residues can deregulate TIP60 s localization during mitotic phases of the cell cycle showing phosphorylation-dependent regulation of TIP60 during mitosis.