VRK1 Phosphorylates Tip60/KAT5 and Is Required for H4K16 Acetylation in Response to DNA Damage

Abstract

Dynamic remodeling of chromatin requires acetylation and methylation of histones, frequently affecting the same lysine residue. These alternative epigenetic modifications require the coordination of enzymes, writers and erasers, mediating them such as acetylases and deacetylases. In cells in G0/G1, DNA damage induced by doxorubicin causes an increase in histone H4K16ac, a marker of chromatin relaxation. In this context, we studied the role that VRK1, a chromatin kinase activated by DNA damage, plays in this early step. VRK1 depletion or MG149, a Tip60/KAT5 inhibitor, cause a loss of H4K16ac. DNA damage induces the phosphorylation of Tip60 mediated by VRK1 in the chromatin fraction. VRK1 directly interacts with and phosphorylates Tip60. Furthermore, the phosphorylation of Tip60 induced by doxorubicin is lost by depletion of VRK1 in both ATM +/+ and ATM−/− cells. Kinase-active VRK1, but not kinase-dead VRK1, rescues Tip60 phosphorylation induced by DNA damage independently of ATM. The Tip60 phosphorylation by VRK1 is necessary for the activating acetylation of ATM, and subsequent ATM autophosphorylation, and both are lost by VRK1 depletion. These results support that the VRK1 chromatin kinase is an upstream regulator of the initial acetylation of histones, and an early step in DNA damage responses (DDR).

VRK1 Depletion Facilitates the Synthetic Lethality of Temozolomide and Olaparib in Glioblastoma Cells

“…The synthetic lethality of VRK1 depletion was also detected when used in combination with ionizing radiation or doxorubicin. VRK1 depletion led to a significant reduction in the dose needed to achieve a similar effect (Campillo- Lazo, 2018, 2019;Garcia-Gonzalez et al, 2020). Recently, a pyrimidine-based inhibitor has shown high affinity and specificity for the VRK1 kinase (Serafim et al, 2019), which can be a candidate for future drug development.…”

“…The loss of H4K16ac is associated with defective DNA repair (Dhar et al, 2017). Moreover, Tip60/KAT5, which is directly phosphorylated and activated by VRK1 in response to DNA damage regulating H4K16 acetylation (Garcia-Gonzalez et al, 2020). Therefore, we studied the effect of VRK1 knockdown on H4K16ac in LN-18 and LN-229 cells that were treated with TMZ and olaparib.…”

Kinome-wide RNAi screen uncovers role of Ballchen in maintenance of gene activation by trithorax group in Drosophila

“…This interplay of VRK1, CREB and CBP is known to increase CREB target genes transcription (Radhakrishnan et al, 1998; Dyson and Wright, 2005). Recently, VRK1 is shown to positively regulate DNA damage repair by phosphorylating Tip60 (García-González et al, 2020). However, discovery of mechanistic basis of BALL mediated phosphorylation in maintenance of gene activation by trxG requires further scrutiny at molecular and biochemical levels.…”

Lysine Methyltransferase Inhibitors Impair H4K20me2 and 53BP1 Foci in Response to DNA Damage in Sarcomas, a Synthetic Lethality Strategy

“…These sequential processes involve changes in covalent modifications of histones (Polo, 2015), which are necessary for the recruitment of specific DNA repair factors. In this context, histone acetylation plays an important role in response to DNA damage, since acetylated histones H3 and H4 are recognized by chromatin remodelers and protein kinases implicated in specific DDR pathways (Deem et al, 2012;Garcia-Gonzalez et al, 2020). Among them, the acetylation of histone H4 in K16 (H4K16ac) induced by DNA damage is also associated with chromatin relaxation (Murr et al, 2006;Garcia-Gonzalez et al, 2020).…”