Projects Offered

1 PhD project offered in the IPP winter call Molecular Mechanisms in Genome Stability & Gene Regulation

Scientific Background

The actin cytoskeleton fulfills essential functions in the context of cell migration, cell shape, mechanical signal transduction and many other aspects of cell biology. Actin is a globular protein that can undergo polymerization into so-called filamentous actin (F-actin). The dynamic nature of cytoplasmic actin polymerization and its regulation in the above-mentioned functions is well-understood based on intense research efforts from recent decades. Despite the huge knowledge we acquired on cytoplasmic actin, there is very little evidence for the existence and function of F-actin inside the nucleus. Only recently, based on technological advances, nuclear actin filaments have been observed and characterized – mainly in the context of key genome stability pathways such as DNA repair and the response to DNA replication stress. Our group is interested in nuclear F-actin-regulated processes with a strong focus on the contribution of myosins as actin-based motor proteins. 

PhD Project: Investigating the nuclear actin cytoskeleton in DNA repair

Nuclear F-actin has recently been shown to support homology-directed repair (HDR) of DNA double-strand breaks (DSBs). Although myosin I and V were identified to move DSBs along nuclear actin filaments in Drosophila, we currently have no insight into the contributions of myosins to DSB repair in human cells. 

Our group recently identified myosin VI as member of the replication protection complex. In addition, we collected preliminary data suggesting a function of myosin VI during DNA repair processes. The aim of this PhD project is to understand and characterize the molecular pathways underlying the functional contribution of the cytoskeletal protein myosin VI addressing the following main questions:

• Does myosin VI cooperate with nuclear F-actin in the resection and mobility steps of the homologous recombination repair pathway?

• How does myosin VI support DNA repair mechanistically? 

• Are other myosins and/or cytoskeletal factors/regulators involved?

Furthermore, the PhD student will work on the probes for visualization of cytoskeletal proteins inside the nucleus.

Methods involve cell culture techniques, fluorescence and high-resolution microscopy, gene editing via CRISPR\Cas9, Flow Cytometry (reporter assays) as well as standard molecular biology (cloning, SDS-PAGE, Western Blotting, etc.). In addition, we will perform specialized assays to monitor DNA repair pathway functions.

This project is pending confirmation for third party funding.

If you are interested in this project, please select Ulrich (Actin) as your group preference in the IPP application platform.

Publications relevant to this project

Shi J, Hauschulte K, Mikicic I, Maharjan S, Arz V, Strauch T, Heidelberger JB, Schaefer JV, Dreier B, Plückthun A, Beli P, Ulrich HD^# and Wollscheid HP^# (2023) Nuclear myosin VI maintains replication fork stability. Nat Commun, 14:3787 (^#indicates joint correspondence) Link

Wollscheid HP^#, Ulrich HD^# (2023) Chromatin meets the cytoskeleton: the importance of nuclear actin dynamics and associated motors for genome stability. DNA Repair (Amst). 31:103571. (^#indicates joint correspondence) Link

He F*, Wollscheid HP*, Nowicka U, Biancospino M, Valentini E, Ehlinger A, Acconcia F, Magistrati E, Polo S, Walters KJ. (2016) Myosin VI Contains a Compact Structural Motif that Binds to Ubiquitin Chains. Cell Rep. 22;14(11):2683-94 (*indicates joint authorship) Link

Wollscheid HP*, Biancospino M*, He F*, Magistrati E, Molteni E, Lupia M, Soffientini P, Rottner K, Cavallaro U, Pozzoli U, Mapelli M, Walters KJ, Polo S. (2016) Diverse functions of myosin VI elucidated by an isoform-specific α-helix domain. Nat Struct Mol Biol. 23(4):300-8 (*indicates joint authorship) Link

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