TIP60, a key lysine acetyltransferase, acts as a wound-induced factor essential for efficient wound response in planaria

Abstract

Chromatin modifiers are essential regulators of gene expression, DNA repair, replication, and cell division. Among them, histone acetyltransferases (HATs) such as TIP60 play a central role in modulating chromatin dynamics through acetylation of histone and non-histone proteins. TIP60, a member of the MYST family of HATs, is known to regulate key cellular processes, including transcriptional activation, DNA damage response, and cell cycle progression. Although TIP60s role in stem cell maintenance and differentiation is well established, its function in stem cell-driven regeneration has remained unexplored. In this study, we characterize the role of the TIP60 homolog, SMED-TIP60, in the planarian Schmidtea mediterranea, a model organism renowned for its regenerative capacity. Biochemical assays confirmed SMED-TIP60s acetyltransferase and auto-acetylation activity. RNAi-mediated knockdown of Smed-tip60 resulted in severe defects in tissue homeostasis, survival, and regeneration, including impaired blastema formation and failure to regenerate tissues. In situ hybridization and immunofluorescence analyses revealed a marked reduction in stem cell populations and mitotic activity. Western blotting showed a peak in SMED-TIP60 expression at 5 days post-amputation, suggesting a role during regeneration. RNA-seq analysis revealed widespread dysregulation of gene expression at both anterior and posterior wounds, correlating with increased TIP60 expression post-injury. Notably, wound-response gene expression was aberrant in Smed-tip60 RNAi animals, indicating TIP60s essential role in initiating wound responses and resetting positional cues. Together, these findings establish TIP60 as a critical regulator of stem cell-mediated regeneration and wound healing in planarians.