Biology subjects

Vorhauser, J.

Publications and source records attributed to Vorhauser, J..

4 recordsLinked to original sources

bioRxiv2024

The mitotic CIP2A-TOPBP1 axis facilitates mitotic pathway choice between MiDAS and MMEJ

Mitotic DNA double-strand breaks (DSBs) accumulate in response to replication stress or BRCA1/2 deficiency posing a significant threat to genome stability as repair by non-homologous end-joining (NHEJ) and homologous recombination (HR) is inactivated in mitosis. Mitotic cells instead rely on the mechanisms of microhomology mediated end-joining (MMEJ) and mitotic DNA synthesis (MiDAS). However, how these pathways are regulated in mitosis remains unknown. Here we reveal the CIP2A-TOPBP1 complex facilitates recruitment of SMX complex components to mitotic chromatin marked by CIP2A, through a CDK1-dependent interaction between TOPBP1 BRCT 1/2 and SLX4 phospho-threonine1260, that drives MiDAS. Furthermore, CIP2A promotes the recruitment of Pol{theta} to facilitate mitotic MMEJ. This defines a mechanistic framework for mitotic DSB repair, where simultaneous disruption of MiDAS and MMEJ pathways underpins the synthetic lethality observed in BRCA1/2-deficient cells following CIP2A depletion. These findings provide critical insights into mitotic DNA repair and highlights therapeutic opportunities in HR deficient tumours.

molecular biology↗

bioRxiv2024

Cell cycle-dependent S-sulfenyl proteomics uncover a redox switch in p21-CDK feedback governing the proliferation-senescence decision

Reactive oxygen species (ROS) influence cell proliferation and fate decisions by oxidizing cysteine residues (S-sulfenylation) of proteins, but specific targets and underlying regulatory mechanisms remain poorly defined. Here, we employ redox proteomics to identify cell cycle-coordinated S-sulfenylation events and investigate their functional role in proliferation control. Although ROS levels rise during cell cycle progression, overall oxidation of the proteome remains constant with dynamic S-sulfenylation restricted to a subset of cysteines. Among these, we identify a critical redox-sensitive cysteine residue (C41) in the cyclin-dependent kinase (CDK) inhibitor p21. C41 oxidation regulates the interaction of p21 with CDK2 and CDK4, controlling a double-negative feedback loop that determines p21 stability. When C41 remains reduced, p21s half-life increases in G2 phase resulting in more p21 inheritance to daughter cells suppressing proliferation and promoting senescence after irradiation. Notably, we identify dynamic S-sulfenylation on further cell cycle regulators implying coordination of cell cycle and redox control.

cell biology↗

bioRxiv2024

High resolution profiling of cell cycle-dependent protein and phosphorylation abundance changes in non-transformed cells

The cell cycle governs a precise series of molecular events, regulated by coordinated changes in protein and phosphorylation abundance, that culminates in the generation of two daughter cells. Here, we present a proteomic and phosphoproteomic analysis of the human cell cycle in hTERT-RPE-1 cells using deep quantitative mass spectrometry by isobaric labelling. Through analysing non-transformed cells, and improving the temporal resolution and coverage of key cell cycle regulators, we present a dataset of cell cycle-dependent protein and phosphorylation site oscillation that offers a foundational reference for investigating cell cycle regulation. These data reveal uncharacterised regulatory intricacies including proteins and phosphorylation sites exhibiting previously unreported cell cycle-dependent oscillation, and novel proteins targeted for degradation during mitotic exit. Integrated with complementary resources, our data link cycle-dependent abundance dynamics to functional changes and are accessible through the Cell Cycle database (CCdb), an interactive web-based resource for the cell cycle community. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=196 SRC="FIGDIR/small/599917v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@bb2a69org.highwire.dtl.DTLVardef@1dd55ecorg.highwire.dtl.DTLVardef@34073eorg.highwire.dtl.DTLVardef@1c7a8c9_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

A ROS-dependent mechanism to drive progression through S phase

Long considered as cytotoxic reagents, reactive oxygen species (ROS) at the right concentration promote cell proliferation in cell culture, stem cells and model organisms. However, how ROS signaling is coordinated with cell cycle progression and integrated into the cell cycle control machinery on the molecular level remains unsolved. Here, we report oscillations of mitochondrial ROS during the cell cycle that target cyclin-dependent kinase 2 (CDK2). Chemical and metabolic interference with ROS production decrease T-loop phosphorylation on CDK2, impeding its full activation and thus efficient DNA replication. ROS regulate CDK2 activity through oxidation of a conserved cysteine residue in close proximity to the T-loop, which prevents binding of the T-loop phosphatase KAP. Together our data reveal how ROS couple mitochondrial metabolism to DNA replication and cell cycle progression, and provide a solution to the longstanding conundrum of how KAP activity towards CDKs can be cell cycle-regulated.

cell biology↗