Biology subjects

Carver, A.

Publications and source records attributed to Carver, A..

3 recordsLinked to original sources

bioRxiv2024

Molecular basis of FIGNL1 in dissociating RAD51 from DNA and chromatin

Maintaining genome integrity is an essential and challenging process. RAD51 recombinase, the central player of several crucial processes in repairing and protecting genome integrity, forms filaments on DNA. RAD51 filaments are tightly regulated. One of these regulators is FIGNL1, that prevents persistent RAD51 foci post-damage and genotoxic chromatin association in cells. The cryogenic electron microscopy structure of FIGNL1 in complex with RAD51 reveals that the FIGNL1 forms a non-planar hexamer and RAD51 N-terminus is enclosed in the FIGNL1 hexamer pore. Mutations in pore loop or catalytic residues of FIGNL1 render it defective in filament disassembly and are lethal in mouse embryonic stem cells. Our study reveals a unique mechanism for removing RAD51 from DNA and provides the molecular basis for FIGNL1 in maintaining genome stability.

biochemistry↗

bioRxiv2021

The transcription factor Roc1 is a regulator of cellulose degradation in the wood-decaying mushroom Schizophyllum commune

Wood-decaying fungi of the class Agaricomycetes (phylum Basidiomycota) are saprotrophs that break down lignocellulose and play an important role in the nutrient recycling. They secrete a wide range of extracellular plant cell wall degrading enzymes that break down cellulose, hemicellulose and lignin, the main building blocks of plant biomass. Although the production of these enzymes is regulated mainly at the transcriptional level, no activating regulators have been identified in any wood-decaying fungus in the class Agaricomycetes. We studied the regulation of cellulase expression in the wood-decaying fungus Schizophyllum commune. Comparative genomics and transcriptomics on two wild isolates revealed a Zn2Cys6-type transcription factor gene (roc1) that was highly up-regulated during growth on cellulose, when compared to glucose. It is only conserved in the class Agaricomycetes. A roc1 knockout strain showed an inability to grow on medium with cellulose as sole carbon source, and growth on cellobiose and xylan (other components of wood) was inhibited. Growth on non-wood-related carbon sources was not inhibited. Cellulase activity was reduced in the growth medium of the {Delta}roc1 strain. ChIP-Seq identified 1474 binding sites of the Roc1 transcription factor. Promoters of genes involved in lignocellulose degradation were enriched with these binding sites, especially those of LPMO (lytic polysaccharide monooxygenase) CAZymes, indicating that Roc1 directly regulates these genes. A GC-rich motif was identified as the binding site of Roc1, which was confirmed by a functional promoter analysis. Together, Roc1 is a key regulator of cellulose degradation and the first identified in wood-decaying fungi in the phylum Basidiomycota.

microbiology↗

bioRxiv2020

Podoplanin drives dedifferentiation and amoeboid invasion of melanoma

Melanoma is an aggressive skin cancer developing from melanocytes, frequently resulting in metastatic disease. Melanoma cells utilise amoeboid migration as mode of local invasion. Amoeboid invasion is characterized by rounded cell morphology and high actomyosin contractility driven by the RhoA signalling pathway. Migrastatic drugs targeting actin polymerization and contractility to inhibit invasion and metastasis are therefore a promising treatment option. To predict amoeboid invasion and metastatic potential, there is a need for biomarkers functionally linked to contractility pathways. The glycoprotein podoplanin drives actomyosin contractility in lymphoid fibroblasts, and is overexpressed in several cancer types. Here, we show that podoplanin enhances amoeboid invasion in melanoma. Expression of podoplanin in murine melanoma models drives rounded cell morphology, increasing motility and invasion in vivo. Podoplanin expression is upregulated in a subset of dedifferentiated human melanoma, and in vitro is sufficient to suppress melanogenesis and upregulate melanoma-associated markers Mitf and Pou3f2. Together, our data indicates that podoplanin is both a potential biomarker for dedifferentiated invasive melanoma and a promising migrastatic therapeutic target.

cancer biology↗