Biology subjects

Boekhout, M.

Publications and source records attributed to Boekhout, M..

5 recordsLinked to original sources

bioRxiv2024

WNT7B drives a program for pancreatic cancer subtype switching and progression

Hyperactivation of WNT signaling is a well-established hallmark of cancer. Various epithelial cancers express high levels of WNT7B and WNT10A that are not commonly expressed during tissue homeostasis, but rather associate with tissue development and regeneration. Although increased WNT7B/10A expression correlates with aggressive disease and lower patient survival rates, the mechanism by which these WNTs influence cancer progression remains unknown. Here, we use patient-derived organoids to show that tumor-intrinsic expression of WNT7B/10A drives survival and growth of advanced pancreatic ductal adenocarcinoma (PDAC). Bulk and single-cell profiling reveal that WNT7B drives proliferation and promotes expression of a poor prognosis basal-like state by preventing expression of a more differentiated, classical PDAC signature. By generating WNT7B reporter organoids, we show that heterogeneously distributed WNT-high PDAC cells are shifted towards a more basal-like phenotype and stably co-exist with WNT-low/negative lineages. Furthermore, hybrid co-cultures of WNT7B-proficient and -knockout PDAC organoids demonstrate that WNT-sending cells drive survival and proliferation of neighboring WNT-negative cells within the cancer epithelium via short range, cell contact-dependent signaling. In summary, our work uncovers a prominent role of WNT7B/10A in driving PDAC subtype heterogeneity and argues that WNT inhibition may be applied to force a class switch to a more differentiated, less aggressive cancer subtype that correlates with improved therapeutical response.

cancer biology↗

bioRxiv2023

Seeding the meiotic DNA break machinery and initiating recombination on chromosome axes

Programmed DNA double-strand break (DSB) formation is a unique meiotic feature that initiates recombination-mediated linking of homologous chromosomes, thereby enabling chromosome number halving in meiosis. DSBs are generated on chromosome axes by heterooligomeric focal clusters of DSB-factors. Whereas DNA-driven protein condensation is thought to assemble the DSB-machinery, its targeting to chromosome axes is poorly understood. We discovered in mice that efficient biogenesis of DSB-machinery clusters requires seeding by axial IHO1 platforms, which are based on a DBF4-dependent kinase (DDK)-modulated interaction between IHO1 and the chromosomal axis component HORMAD1. IHO1-HORMAD1-mediated seeding of the DSB-machinery on axes ensures sufficiency of DSBs for efficient pairing of homologous chromosomes. Without IHO1-HORMAD1 interaction, residual DSBs depend on ANKRD31, which enhances both the seeding and the growth of DSB-machinery clusters. Thus, recombination initiation is ensured by complementary pathways that differentially support seeding and growth of DSB-machinery clusters, thereby synergistically enabling DSB-machinery condensation on chromosomal axes.

cell biology↗

bioRxiv2023

Essential roles of the ANKRD31-REC114 interaction in meiotic recombination and mouse spermatogenesis

Meiotic DNA double-strand breaks (DSBs) initiate homologous recombination and are crucial for ensuring proper chromosome segregation. In mice, ANKRD31 recently emerged as a regulator of DSB timing, number, and location, with a particularly important role in targeting DSBs to the pseudoautosomal regions (PARs) of sex chromosomes. ANKRD31 interacts with multiple proteins, including the conserved and essential DSB-promoting factor REC114, so it was hypothesized to be a modular scaffold that "anchors" other proteins together and to meiotic chromosomes. To determine if and why the REC114 interaction is important for ANKRD31 function, we generated mice with Ankrd31 mutations that either reduced (missense mutation) or eliminated (C-terminal truncation) the ANKRD31- REC114 interaction without diminishing contacts with other known partners. A complete lack of the ANKRD31-REC114 interaction mimicked an Ankrd31 null, with delayed DSB formation and recombination, defects in DSB repair, and altered DSB locations including failure to target DSBs to the PARs. In contrast, when the ANKRD31- REC114 interaction was substantially but not completely disrupted, spermatocytes again showed delayed DSB formation globally, but recombination and repair were hardly affected and DSB locations were similar to control mice. The missense Ankrd31 allele showed a dosage effect, wherein combining it with the null or C-terminal truncation allele resulted in intermediate phenotypes for DSB formation, recombination, and DSB locations. Our results show that ANKRD31 function is critically dependent on its interaction with REC114, and that defects in ANKRD31 activity correlate with the severity of the disruption of the interaction. SignificanceHomologous recombination initiated by double-strand breaks (DSBs) during meiosis is a nearly universal feature of eukaryotic lifecycles, but is also dangerous because DSBs are potentially toxic or mutagenic. The vertebrate-specific protein ANKRD31 is an important regulator of DSB formation, proposed to be a scaffold protein that coordinates the activities of multiple DSB-promoting factors, including the widely conserved REC114. We test this hypothesis here through generation of targeted Ankrd31 mutations that specifically attenuate or eliminate the ANKRD31-REC114 interaction. Analysis of this allelic series demonstrates that the ANKRD31-REC114 interaction is essential for all ANKRD31 activities in vivo, providing insight into how ANKRD31 controls DSB locations, timing, and number.

genetics↗

bioRxiv2019

Ensuring meiotic DNA break formation in the mouse pseudoautosomal region

Sex chromosomes in males share only a diminutive homologous segment, the pseudoautosomal region (PAR), wherein meiotic double-strand breaks (DSBs), pairing, and crossing over must occur for correct segregation. How cells ensure PAR recombination is unknown. Here we delineate cis-and trans-acting factors that control PAR ultrastructure and make the PAR the hottest area of DSB formation in the male mouse genome. Prior to DSB formation, PAR chromosome axes elongate, sister chromatids separate, and DSB-promoting factors hyperaccumulate. These phenomena are linked to mo-2 minisatellite arrays and require ANKRD31 protein. We propose that the repetitive PAR sequence confers unique chromatin and higher order structures crucial for DSB formation, X-Y pairing, and recombination. Our findings establish a mechanistic paradigm of mammalian sex chromosome segregation during spermatogenesis.

molecular biology↗

bioRxiv2018

REC114 partner ANKRD31 controls number, timing and location of meiotic DNA breaks

Double-strand breaks (DSBs) initiate the homologous recombination that is crucial for meiotic chromosome pairing and segregation. Here we unveil mouse ANKRD31 as a lynchpin governing multiple aspects of DSB formation. Spermatocytes lacking ANKRD31 have altered DSB locations and fail to target DSBs to sex chromosomes pseudoautosomal regions (PAR). They also have delayed/fewer recombination sites but, paradoxically, more DSBs, suggesting DSB dysregulation. Unrepaired DSBs and pairing failures--stochastic on autosomes, nearly absolute on X and Y--cause meiotic arrest and sterility in males. Ankrd31-deficient females have reduced oocyte reserves. A crystal structure defines direct ANKRD31- REC114 molecular contacts and reveals a surprising pleckstrin homology domain in REC114. In vivo, ANKRD31 stabilizes REC114 association with the PAR and elsewhere. Our findings inform a model that ANKRD31 is a scaffold anchoring REC114 and other factors to specific genomic locations, promoting efficient and timely DSB formation but possibly also suppressing formation of clustered DSBs.

genetics↗