Biology subjects

Bange, T.

Publications and source records attributed to Bange, T..

7 recordsLinked to original sources

bioRxiv2026

Proteomics-Based Discovery of Symmetry-Specific Readers and Antireaders of 5-Formylcytosine in Mammalian DNA

5-methylcytosine (mC) and its oxidized derivatives are epigenetic modifications of mammalian DNA that play key roles in transcription, cell differentiation, and cancer. They predominantly occur within palindromic CpG dyads, creating multiple possible combinations across the two dyad strands, each representing a chemically distinct DNA major groove mark. Among the modifications, 5-formylcytosine (fC) interacts with a large number of proteins and has been associated with important roles in chromatin regulation. However, it is poorly understood whether nuclear proteins selectively recognize the symmetry of individual fC-containing CpG dyads. Here, we report the first proteome-wide interaction profiles of symmetric and asymmetric fC modifications in mammalian DNA. Our analysis spans several human and mouse cell lines and three DNA promoter probes containing CpG dyads with five distinct combinations of fC, C, and mC nucleobases. We identify a diverse set of fC reader proteins with distinct symmetry preferences, including transcription factors (e.g., MAX, HEY1, RFX5, SIX1, SIX2, and FOXJ3) and DNA repair proteins (MPG and TDG). Notably, some proteins act as fC readers or anti-readers depending on the sequence context, suggesting a role for fC in modulating their target selection. Our data reveal widespread symmetry-specific recognition of fC by mammalian proteins and provide a rich resource for studying its potential functions in chromatin regulation. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=183 HEIGHT=200 SRC="FIGDIR/small/717454v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@10773borg.highwire.dtl.DTLVardef@103ced4org.highwire.dtl.DTLVardef@fff20eorg.highwire.dtl.DTLVardef@16c9678_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Proximity-based activation of AURORA A by MPS1 potentiates error correction

Faithfull cell division relies on mitotic chromosomes becoming bioriented with each pair of sister kinetochores bound to microtubules oriented toward opposing spindle poles. Erroneous kinetochore-microtubule attachments often form during early mitosis, but are destabilized through the phosphorylation of outer kinetochore proteins by centromeric AURORA B kinase (ABK) and centrosomal AURORA A kinase (AAK), thus allowing for re-establishment of attachments until biorientation is achieved. MPS1-mediated phosphorylation of NDC80 has also been shown to directly weaken the kinetochore-microtubule interface in yeast. In human cells, MPS1 has been proposed to transiently accumulate at end-on attached kinetochores and phosphorylate SKA3 to promote microtubule release. Whether MPS1 directly targets NDC80 and/or promotes the activity of AURORA kinases in metazoans remains unclear. Here, we report a novel mechanism involving communication between kinetochores and centrosomes, wherein MPS1 acts upstream of AAK to promote error correction. MPS1 on pole-proximal kinetochores phosphorylates the C-lobe of AAK thereby increasing its activation at centrosomes. This proximity-based activation ensures the establishment of a robust AAK activity gradient that locally destabilizes mal-oriented kinetochores near spindle poles. Accordingly, MPS1 depletion from Drosophila cells causes severe chromosome misalignment and erroneous kinetochore-microtubule attachments, which can be rescued by tethering either MPS1 or constitutively active AAK mutants to centrosomes. Proximity-based activation of AAK by MPS1 also occurs in human cells to promote AAK-mediated phosphorylation of the NDC80 N-terminal tail. These findings uncover an MPS1-AAK cross-talk that is required for efficient error correction, showcasing the ability of kinetochores to modulate centrosome outputs to ensure proper chromosome segregation.

cell biology↗

bioRxiv2024

Condensin II activation by M18BP1

Condensin complexes promote the drastic spatial rearrangement of the genome upon mitotic entry. Condensin II initiates chromosome condensation in early mitosis. To prevent chromosome condensation during interphase, condensin II is inhibited by MCPH1, but the mechanism is unknown. Through genetic and proteomic approaches, we identify M18BP1, a protein previously associated with centromere identity, as a factor required for condensin II localization to chromatin. M18BP1 directly binds condensin IIs CAP-G2 subunit and competes with MCPH1 for binding. Upon mitotic entry, CDK1 mediated phosphorylation may promote a switch from MCPH1 to M18BP1 binding to activate condensin II. Our results identify a fundamental and evolutionarily conserved mechanism of condensin II activation.

cell biology↗

bioRxiv2021

An integrative omics approach reveals posttranscriptional mechanisms underlying circadian temperature compensation

A defining property of circadian clocks is temperature compensation, characterized by the resilience of circadian free-running periods against changes in environmental temperature. As an underlying mechanism, the balance or critical reaction hypothesis have been proposed. While the former supposes a temperature-dependent balancing of reactions with opposite effects on circadian period, the latter assumes an insensitivity of certain critical period determining regulations upon temperature changes. Posttranscriptional regulations such as temperature-sensitive alternative splicing or phosphorylation have been described as underlying reactions. Here, we show that knockdown of cleavage and polyadenylation specificity factor subunit 6 (CPSF6), a key regulator of 3-end cleavage and polyadenylation, abolishes circadian temperature compensation in U-2 OS cells. We apply a combination of 3-End-RNA-seq and mass spectrometry-based proteomics to globally quantify changes in 3 UTR length as well as gene and protein expression between wild type and CPSF6 knock-down cells and their dependency on temperature. Analyzing differential responses upon temperature changes in wild type and CPSF6 knockdown cells reveals candidate genes underlying circadian temperature compensation. We identify that eukaryotic translation initiation factor 2 subunit 1 (EIF2S1) is among these candidates. EIF2S1 is known as a master regulator of cellular stress responses that additionally regulates circadian rhythms. We show that knockdown of EIF2S1 furthermore impairs temperature compensation, suggesting that the role of CPSF6 in temperature compensation may be mediated by its regulation of EIF2S1.

genomics↗

bioRxiv2020

Cdk1-dependent destabilization of long astral microtubules is required for spindle orientation

The precise execution of mitotic spindle orientation in response to cell shape cues is important for tissue organization and development. The presence of astral microtubules extending from the centrosome towards the cell cortex is essential for this process, but little is understood about the contribution of astral microtubule dynamics to spindle positioning, or how astral microtubule dynamics are regulated spatiotemporally. The mitotic regulator Cdk1-CyclinB promotes destabilization of centrosomal microtubules and increased microtubule dynamics as cells transition from interphase to mitosis, but how Cdk1 activity specifically modulates astral microtubule stability, and whether it impacts spindle positioning, is unknown. Here we uncover a mechanism revealing that Cdk1 destabilizes astral microtubules to ensure spindle reorientation in response to cell shape. Phosphorylation of the EB1-dependent microtubule plus-end tracking protein GTSE1 by Cdk1 in early mitosis abolishes its interaction with EB1 and recruitment to microtubule plus-ends. Loss of Cdk1 activity, or mutation of phosphorylation sites in GTSE1, induces recruitment of GTSE1 to growing microtubule plus-ends in mitosis. This decreases the catastrophe frequency of astral microtubules, and causes an increase in the number of long astral microtubules reaching the cell cortex, which restrains the ability of cells to reorient spindles along the long cellular axis in early mitosis. Astral microtubules must thus not only be present, but also dynamic to allow the spindle to reorient in response to cell shape, a state achieved by selective destabilization of long astral microtubules via Cdk1.

cell biology↗

bioRxiv2019

Clathrin’s adaptor interaction sites are repurposed to stabilize microtubules during mitosis

Clathrin plays an important role to ensure mitotic spindle stability and efficient chromosome alignment, independently of its well-characterized functions in vesicle trafficking. While clathrin clearly localizes to the mitotic spindle and kinetochore-fiber microtubule bundles, the mechanisms by which clathrin stabilizes microtubules have remained elusive. Here we show that clathrin adaptor interaction sites on clathrin heavy chain (CHC) are repurposed during mitosis to directly recruit the microtubule-stabilizing protein GTSE1 to the mitotic spindle. Structural analyses reveal that multiple clathrin-box motifs on GTSE1 interact directly with different clathrin adaptor interaction sites on CHC, in a manner structurally analogous to that which occurs between adaptor proteins and CHC near membranes. Specific disruption of this interaction in cells releases GTSE1 from spindles and causes defects in chromosome alignment. Surprisingly, this disruption causes destabilization of astral microtubules, but not kinetochore-microtubule attachments, and the resulting chromosome alignment defect is due to a failure of chromosome congression independent of kinetochore-microtubule attachment stability. Finally, we show that GTSE1 recruited to the spindle by clathrin stabilizes microtubules and promotes chromosome congression by inhibiting the activity of the microtubule depolymerase MCAK. This work thus uncovers a novel role of clathrin to stabilize non-kinetochore-fiber microtubules to support chromosome congression. This role is carried out via clathrin adaptor-type interactions of CHC with GTSE1, defining for the first time an important repurposing of this endocytic interaction mechanism during mitosis.

cell biology↗

bioRxiv2019

Mps1 releases Mad1 from nuclear pores to ensure a robust mitotic checkpoint and accurate chromosome segregation

The strength of the Spindle Assembly Checkpoint (SAC) depends on the amount of the Mad1-C-Mad2 heterotetramer at kinetochores but also on its binding to Megator/Tpr at nuclear pore complexes (NPCs) during interphase. However, the molecular underpinnings controlling the spatiotemporal redistribution of Mad1-C-Mad2 as cells progress into mitosis remain elusive. Here, we show that Mps1-mediated phosphorylation of Megator/Tpr abolishes its interaction with Mad1 in vitro and in Drosophila cells. Timely activation of Mps1 during prophase triggers Mad1 release from NPCs, which we find to be required for competent kinetochore recruitment of Mad1-C-Mad2 and robust checkpoint response. Importantly, preventing Mad1 binding to Megator/Tpr rescues the fidelity of chromosome segregation and aneuploidy in larval neuroblasts of Drosophila mps1-null mutants. Our findings demonstrate that the subcellular localization of Mad1 is stringently coordinated with cell cycle progression by kinetochore-extrinsic activity of Mps1. This ensures that both NPCs in interphase and kinetochores in mitosis can generate anaphase inhibitors to efficiently preserve genomic stability.

cell biology↗