Functional analyses of the novel H2A.Z chaperone/remodeler complex members MBTD1 and JAZF1

• Applicant: Professorin Dr. Sandra Brigitte Hake
• Subject Area: General Genetics and Functional Genome Biology ; Biochemistry
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269853135

Chromatin is the biochemical template for all DNA-related eukaryotic cellular processes and its structural conformation needs to be tightly regulated. Important players in these regulatory mechanisms are specialized histone variant proteins. H2A.Z is an essential and evolutionary highly conserved histone variant implicated in gene regulation, DNA repair and chromosome stability. In humans, three H2A.Z variants exist that are deposited into chromatin by two large chaperone/remodeling complexes, p400/NuA4/TIP60 (p400) and SRCAP. When analyzing H2A.Z-associated complexes in quantitative mass spectrometry (qMS), we identified MBTD1 and JAZF1, whose biological functions are not well understood. Reciprocal qMS analysis of the MBTD1 and JAZF1 interactomes revealed that they both belong to a share p400 sub-complex that lacks ANP32E, and that they do not bind to the SRCAP chaperone complex. Furthermore, our unpublished studies provide evidence that JAZF1 and MBTD1 are found at micrococcal nuclease inaccessible chromatin regions. Using domain deletion constructs in microscopic assays and FRAP studies, we were able to identify the domains needed for MBTD1 and JAZF1 proper nuclear targeting and chromatin or complex binding. Furthermore, preliminary data hint towards a role of these proteins in gene regulation and DNA damage repair. Our aim is to determine how MBTD1 and JAZF1 interact with p400 complex members and/or each other and what their roles in H2A.Z deposition, gene regulation and DNA damage repair are. With this work we hope to shed light on the function of two proteins that are not well-characterized yet and might play important novel roles in epigenetic processes involving the essential histone variant H2A.Z that we and other have shown to be an important driver of different types of cancer.

• DFG Programme: Research Grants