Biology subjects

Warner, H.

Publications and source records attributed to Warner, H..

4 recordsLinked to original sources

bioRxiv2025

Tetraspanin CD82 reduces the formation of CADM1 oligomers

CD82 is a member of the tetraspanin protein superfamily and known as a metastasis suppressor. We identified cell adhesion molecule 1 (CADM1) as an interaction partner of CD82. CADM1 mediates cell adhesion by forming cis and trans oligomers that connect membranes. We show that CD82 reduces the formation of CADM1 oligomers when solubilized by detergent, on liposomes and in cellulo using Jurkat T-cells. Our data is consistent with a 1:1 complex of CD82 and CADM1 in cis that leaves the CADM1 trans-interaction site accessible. Cryo-electron microscopy of the CD82:CADM1 heterodimer suggests an interaction site between the large-extracellular loop of CD82 and an Ig-like domain of CADM1. Consistently, liposomes coupled with CADM1 ectodomain show reduced clustering when reconstituted with CD82. We hypothesize that CD82 may affect spacing of the transmembrane helices of CADM1, possibly by interacting with the extracellular Ig-like domains and hence disrupting CADM1 oligomerization between membranes.

biochemistry↗

bioRxiv2025

Inhibition of SHP-1 /2 blocks antigen cross-presentation by human macrophages and dendritic cells

PD-1 immune checkpoint therapy aims to stimulate T-cell responses against cancer, but faces challenges due to resistance, rendering it ineffective for a significant subset of patients. Inhibitors of SHP-1 and SHP-2, widely expressed protein tyrosine phosphatases known for their pro-cancer and immunosuppressive properties, have attracted attention for their potential to enhance therapy efficacy and overcome resistance when combined with immune checkpoint PD-1 blockade. However, how SHP-1/2 inhibition affects antigen presenting cells is incompletely understood. In this study, we evaluated the effect of SHP-1/2 inhibition on antigen cross-presentation by human monocyte-derived macrophages and dendritic cells, using T cell reporter cell lines specific for epitopes derived from cancer antigens NY-ESO-1 and gp100. Our findings indicate that SHP-1/2 inhibitor NSC-87877 significantly reduces the cross-presentation efficiency of both antigens. Mechanistically, we show that SHP-1/2 inhibition blocks endo/lysosomal acidification and the activation of cathepsin proteases. The reduction of antigen cross-presentation upon SHP-1/2 inhibition potentially limits the effectiveness of the combination therapy with immune checkpoint inhibition.

immunology↗

bioRxiv2025

CIP2A is required for mitotic recruitment of the SLX1/XPF/MUS81 tri-nuclease complex to replication stress-induced DNA lesions to maintain genome integrity

Perturbed DNA replication can lead to incompletely replicated DNA when cells enter mitosis and can interfere with chromosome segregation. Cells therefore require mechanisms to resolve these lesions during mitosis. The CIP2A-TOPBP1 complex is described to function as a molecular tether that connects fragmented DNA molecules. However, whether CIP2A also functions in processing of incompletely replicated DNA remained unclear. We show that CIP2A-TOPBP1 forms large filamentous structures at sites of incomplete DNA replication during mitosis, which recruit the SMX tri-nuclease complex members SLX4, MUS81 and ERCC1/XPF. These structures form in proximity to sites of mitotic DNA synthesis, although CIP2A is not required for mitotic DNA synthesis. In addition to its globular and coiled-coil domain, the unstructured C-terminal domain of CIP2A is essential for CIP2A-TOPBP1 filamentous structure formation and recruitment of the SMX complex. BRCA1-/- and BRCA2-/- cells have increased mitotic DNA lesions that recruit CIP2A and SLX4. We show that the C-terminal part of CIP2A is required for survival of BRCA2-/- cells. Moreover, SLX4 is crucial for genome stability in BRCA2-/- cells. Combined, we demonstrate that CIP2A-TOPBP1 recruits the SMX complex during mitosis, which is required to resolve mitotic DNA lesions, allows faithful chromosome segregation and maintain viability of BRCA2-/- cells.

cell biology↗

bioRxiv2023

Cofilin-Driven Nuclear Deformation Drives Dendritic Cell Migration through the Extracellular Matrix

To mount an adaptive immune response, dendritic cells must process antigens, migrate to lymph nodes and form synapses with T cells. Critical to 3D migration and mechano-sensing is the nucleus, which is the size-limiting barrier for navigation through gaps in the extracellular matrix. Here, we show that inflammatory activation of dendritic cells leads to the nucleus becoming spherically deformed, adopting a raison-like shape and enables dendritic cells to overcome the typical 2 - 3-micron pore limit for 3D-migration. We show that the nuclear shape-change is partially attained through reduced cell adhesion, whereas improved migration through extracellular matrix is achieved through reprogramming of the actin cytoskeleton. Specifically we show that cofilin-1 is phosphorylated at serine 41 drives the assembly of a Cofilin-ActoMyosin (CAM)-ring proximal to the nucleus and enhancing migration through 3D collagen gels. In summary, these data describe novel signaling events through which dendritic cells simultaneously deform their nucleus and enhance their migratory capacity; molecular events that may be re-capitulated in other contexts such as wound healing and cancer.

cell biology↗