Biology subjects

Reitsma, J.

Publications and source records attributed to Reitsma, J..

3 recordsLinked to original sources

bioRxiv2025

Human cytomegalovirus regulates host DNA repair machinery for viral genome integrity

The DNA damage response (DDR) encompasses a multitude of interconnected pathways that serve as a cellular defense to protect genome integrity. Dysregulation or failure of these pathways results in cancers and genetic disease. DNA viruses, including the herpesvirus cytomegalovirus (CMV), activate DDR signaling during their replicative program. The mechanisms by which they commandeer these responses for replication of their genome is less well understood. Here, we define a viral protein, UL138, that modulates the activity of host DDR pathways. The loss of UL138 results in structural variants, including inversion, deletions, duplication, with signature of homology-directed repair and other DDR pathways. The actions of UL138 are due, in part, to its modulation of pathways regulated by the cellular deubiquitinating complex that targets proliferating cell nuclear antigen (PCNA) and Fanconi Anemia effectors, FANCD2 and FANCI. However, we also show that UL138 accesses pathways independent of USP1-PCNA/FANCD2/FANCI. Disruption of UL138 or these pathways impacts viral genome replication and had consequences for viral genome integrity. This work provides mechanistic insight into the long-standing questions of how DNA viruses recruit, modulate and use cellular DDR pathways. It also puts forth CMV as a model system for further defining these pathways in human cells. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/683233v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@121e55borg.highwire.dtl.DTLVardef@58d8b7org.highwire.dtl.DTLVardef@fc1628org.highwire.dtl.DTLVardef@12b32a_HPS_FORMAT_FIGEXP M_FIG C_FIG Major findingsO_LIUL138 protects HCMV genome integrity through its interaction with USP1-PCNA/FANCD2/FANCI and repeat sequence-mediated pathways C_LIO_LIUL138 protects HCMV genome integrity in the UL region by mechanisms independent of repeat sequences and USP1-PCNA/FANCD2/FANCI C_LIO_LICollectively, US and UL regions of the HCMV genome have fundamentally different pathways acting on them and UL138 modulates DNA damage and repair pathway choice. C_LI

microbiology↗

bioRxiv2025

Proteome-Wide Discovery of Degradable Proteins Using Bifunctional Molecules

Targeted protein degradation (TPD) is an emergent therapeutic strategy with the potential to circumvent challenges associated with targets unamenable to conventional pharmacological inhibition. Among TPD approaches, Proteolysis Targeting Chimeras (PROTACs) have shown marked advancement with numerous candidates in clinical development. Despite their potential, most PROTACs utilize advanced small molecule inhibitors, inherently limiting the scope of this approach. More generally, the fraction of the proteome tractable to PROTAC-type strategies is unknown. Here, we describe a chemical proteomic strategy for the agnostic discovery of degradable human proteins in cells using a new class of bifunctional degrader molecules called "AgnoTACs". Proteome-wide screening of 72 AgnoTACs in human cells uncovered downregulation events spanning >50 functionally and structurally diverse proteins, most of which lack chemical probes. Our findings highlight the potential of function-biased chemical libraries coupled with proteomic profiling to discover degrader starting points as well as furnish a blueprint for expanding our understanding of the chemically degradable proteome.

biochemistry↗

bioRxiv2022

An extracellular vesicle targeting ligand that binds to Arc proteins and facilitates Arc transport in vivo

Communication between distant cells can be mediated by extracellular vesicles (EVs) that deliver proteins and RNAs to recipient cells. Little is known about how EVs are targeted to specific cell types. Here we identify the Drosophila cell-surface protein Stranded at second (Sas) as a targeting ligand for EVs. Full-length Sas is present in EV preparations from transfected Drosophila Schneider 2 (S2 cells). Sas is a binding partner for the Ptp10D receptor tyrosine phosphatase, and Sas-bearing EVs preferentially target to cells expressing Ptp10D. We used co-immunoprecipitation and peptide binding to show that the cytoplasmic domain (ICD) of Sas binds to dArc1. dArc1 and mammalian Arc are related to retrotransposon Gag proteins. They form virus-like capsids which encapsulate Arc and other mRNAs and are transported between cells via EVs. The Sas ICD contains a motif required for dArc1 binding that is shared by the mammalian and Drosophila amyloid precursor protein (APP) orthologs, and the Sas and APP ICDs also bind to mammalian Arc. Sas facilitates delivery of dArc1 capsids bearing dArc1 mRNA into distant Ptp10D-expressing recipient cells in vivo.

cell biology↗