Biology subjects

Clevers, H. C.

Publications and source records attributed to Clevers, H. C..

4 recordsLinked to original sources

bioRxiv2024

Lgr5+ ductal cells of von Ebner's glands are stem cells for turnover of posterior tongue taste buds

Taste bud cells have a limited lifespan and must be continuously replaced along with the papilla epithelium in which they reside. Previous work has shown that expression of leucine- rich G protein-coupled receptor 5 (Lgr5), a Wnt pathway agonist, serves as a marker of adult stem/progenitor cells for taste buds located in posterior tongue (circumvallate and foliate), but not anterior tongue (fungiform), taste papillae. However, the specific location/niche of the Lgr5-expressing cells supporting renewal and their phenotypic properties have not been fully explored. To address this, the genesis and fate of Lgr5+ cells were examined in developing and adult mice using genetic reporter strains. Evidence from Lgr5-lacZ and Lgr5- GFP mice shows that, while Lgr5 is broadly expressed in the epithelium of nascent circumvallate papillae and their trenches during embryonic development, it becomes concentrated within the ducts of adjacent von Ebners salivary glands during the first postnatal week, co-incident with the appearance of differentiated taste buds. In posterior tongue taste papillae of adult animals, sites of highest Lgr5 expression are found in excretory ducts, restricted to the outer (basal) layer of the bi-layered excretory zone. These Lgr5+ cells are immunoreactive for keratin 14, like cells in the basal layer of extragemmal taste epithelium, and for Sox9, a marker of exocrine gland duct cells. Lineage tracing experiments with an Lgr5-EGFP-IRES-CreERT2;R26-mTmG reporter show that Lgr5+ ductal cells become labeled one day following Cre induction, prior to the appearance of descendent cells in taste buds and extragemmal epithelium. These data support a role for Lgr5+ ductal cells as stem cells and suggest that a cooperative interaction exists between posterior taste epithelium and its associated salivary glands in taste cell turnover.

developmental biology↗

bioRxiv2023

Binucleated human hepatocytes arise through loss of membrane anchorage to the midbody during endomitosis

Many plant and animal cells transition from canonical to non-canonical cell cycles during development, resulting in the formation of polyploid cells. Two types of non-canonical cell cycles exist: endoreplication, where cells increase their DNA content without entering M phase, and endomitosis, where cells enter M phase but exit prematurely. Although endoreplication has been extensively studied in plants and insects, much less is known on the regulation of endomitosis, which is the most common mode of polyploidization in mammals. In this study, we use fetal-derived human hepatocyte organoids (Hep-Org), to investigate how human hepatocytes initiate and execute endomitosis. We find that cells in endomitosis M phase have normal mitotic timings, but lose membrane anchorage to the midbody during cytokinesis, resulting in regression of the cytokinetic furrow and formation of binucleate cells. Using immunofluorescence, we find that three cortical anchoring proteins, RacGAP1, anillin, and citron kinase (CIT-K), lose their association with the cell cortex during cytokinetic regression. Moreover, reduction of WNT activity by withdrawal of CHIR99021, a GSK3 inhibitor, from the culturing medium increases the percentage of binucleated cells in Hep-Orgs. This effect is lost in organoids with mutations in the atypical E2F proteins, E2F7 and E2F8, which have been implicated in binucleation of rodent hepatocytes. Together, our results identify how human hepatocytes inhibit cell division in endomitosis, and highlight an evolutionary recurrent mechanism to initiate non-canonical cell cycles in mammals.

cell biology↗

bioRxiv2021

Rewiring glucose metabolism improves 5-FU efficacy in glycolytic p53-deficient colorectal tumors

5-fluorouracil (5-FU) is the backbone for chemotherapy in colorectal cancer (CRC). Response rates in patients are, however, limited to 50%. Despite the importance of 5-FU, the molecular mechanisms by which it induces toxicity remain unclear, limiting the development of strategies to improve efficacy. How fundamental aspects of cancer, such as driver mutations and phenotypic intra-tumor heterogeneity, relate to the 5-FU response is also ill-defined. This is largely due to the shortage of mechanistic studies executed in pre-clinical models that can faithfully recapitulate key CRC features. Here, we analyzed the 5-FU response in human organoids genetically engineered to reproduce the different stages of CRC progression. We find that 5-FU induces pyrimidine imbalance, which leads to DNA damage and cell death. Actively proliferating cancer (stem) cells are accordingly efficiently targeted by 5-FU. Importantly, p53 behaves as a discriminating factor for 5-FU sensitivity, whereas p53-deficiency leads to DNA damage-induced cell death, active p53 protects from these effects through inducing cell cycle arrest. Moreover, we find that targeting the Warburg effect, by rewiring glucose metabolism, enhances 5-FU toxicity by further altering the nucleotide pool and without increasing toxicity in healthy-non-transformed cells. Thus, targeting cancer metabolism in combination with replication stress-inducing chemotherapies emerges as a promising strategy for CRC treatment.

cancer biology↗

bioRxiv2020

Evaluating CRISPR-based Prime Editing for cancer modeling and CFTR repair in intestinal organoids

Prime editing is a recently reported genome editing tool employing a nickase-cas9 fused to a reverse transcriptase that directly synthesizes the desired edit at the target site. The technique holds great promise for clinical application due to its versatility. Here, we explore the use of prime editing in human intestinal organoids. Common TP53 mutations were modeled in human adult stem cell with notable efficiency differences. Next, we functionally repaired the cystic fibrosis CFTR-F508del mutation and compared prime editing to CRISPR/Cas9-mediated homology directed repair and adenine base editing on the CFTR-R785* mutation. Despite encountering varying editing efficiencies and undesired mutations, these results underline the broad applicability of prime editing for modeling oncogenic mutations and showcase the potential clinical application of this technique, pending further optimization.

genetics↗