Understanding the multivalent binding properties of PWWP2A
Cell Biology
Final Report Abstract
Histone variants endow chromatin with unique properties and are involved in the control of all DNA-based processes. The evolutionary conserved H2A.Z variant participates in the regulation of transcription, cell cycle progression, chromosome stability and DNA damage repair. Recently, we have identified PWWP2A as a novel H2A.Z-nucleosome binding protein. PWWP2A is vertebrate-specific and contains two proline-rich stretches, an unusual internal region of no sequence homology to other proteins, a serine-rich stretch and a conserved PWWP domain. PWWP2A interacts with chromatin using a multivalent binding mode and regulates gene transcription, is crucial for metaphase-anaphase transition in human tissue culture cells and is responsible for proper cranial-facial development in Xenopus. In this project, we have now investigated what functional role PWWP2A plays during DNA damage repair, since we have identified H2A.XS139ph (γ-H2A.X) and MDC1, which are essential during DNA damage recognition and repair, as novel PWWP2A interactors. We applied different in vivo approaches to understand the functional relevance of PWWP2A in recognition and/or repair of DNA damage. We could show that PWWP2A is not required for H2A.X deposition and genome-wide localization. Further, PWWP2A is not involved in H2A.X-phosphorylation upon DNA damage and does not contribute to DNA-damage repair. We have now developed tools to investigate whether PWWP2A directly or indirectly via MDC1 binds γ-H2A.X nucleosomes. Additionally, we have succeeded in generating PWWP2A depleted mouse embryonic stem cells to investigate the function of PWWP2A during differentiation.
