Functional and mechanistic analysis of the novel H2A.Z-binding protein MIER1

• Applicant: Professorin Dr. Sandra Brigitte Hake
• Subject Area: General Genetics and Functional Genome Biology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 495223705

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. Using quantitative mass spectrometry screens, we identified MIER1 as a novel H2A.Z binding protein that is able to interact with free H2A.Z-H2B dimers as well as H2A.Z-containing nucleosomes. MIER1 is vertebrate-specific, exists in several alternative spliced isoforms and contains an N-terminal glutamate (Glu)-rich region, an HDAC1-interacting ELM2 and a C-terminal SANT domain. Preliminary results indicate that MIER1 interacts with H2A.Z via its Glu-rich region and is a potential new member of the H2A.Z-specific chaperone complex SRCAP.Now, we plan to investigate whether i) MIER1 directly interacts with H2A.Z and which H2A.Z region mediates MIER1 binding, ii) MIER1 is – together with SRCAP – involved in H2A.Z deposition and iii) MIER1 regulates transcription, cell cycle control and/or cell differentiation. Here, we will apply quantitative in vitro binding assays with recombinant nucleosomes and MIER1 to determine how and with which H2A.Z regions MIER1 interacts. Additionally, we will utilize different whole genome in vivo approaches, such as ChIP-seq and RNA-seq, to understand the functional relevance of MIER1 in H2A.Z deposition, gene regulation, cell cycle control and/or stem cell differentiation. We will generate MIER knock-out and or inducible knock-down cell lines using CRISPR-Cas9 technology and tag the endogenous MIER1 locus for IP experiments.In summary, we will apply state-of-the-art experiments to understand the functional relevance of MIER1 in H2A.Z-controlled processes, such as e.g. gene regulation.

• DFG Programme: Research Grants