Biology subjects

Meier, P.

Publications and source records attributed to Meier, P..

12 recordsLinked to original sources

bioRxiv2026

Invisible shield: Sprayable supramolecular antimicrobial microscale films for preventing wound and medical device infections

Wound and device-associated infections remain difficult to eradicate because biofilms block host immunity and antibiotics, accelerating chronicity and resistance. Here, we present a portable, low-cost dual-syringe spray that deposits an ultra-thin, self-assembling antimicrobial film directly on wounds and implant surfaces. The device co-delivers oppositely charged hyaluronic acid (HA) and a cationic antimicrobial peptide (polyarginine, PAR30), which rapidly form a conformal nanometric polyelectrolyte complex at the tissue-material interface. Molecular dynamics simulation revealed pronounced positional heterogeneity within the PAR30/HA complex and identified an N-terminal arginine as a dominant interaction hotspot. The resulting coating adheres to diverse substrates, kills bacteria on contact, prevents biofilm formation, and sustains antimicrobial efficacy. Across vitro assays and murine wound infection models, treatment produced 4 to 5 log reductions in bacterial burden against methicillin-resistant Staphylococcus aureus and Gram-negative pathogens, including Pseudomonas aeruginosa and Escherichia coli. The formulation is biocompatible, did not increase cutaneous inflammation or IL-6 levels in vivo, and reduced post-surgical pain and motor deficits in a mouse incision model. To our knowledge, this is the first antimicrobial treatment system applicable to both tissues and medical devices. Developed under a safe-and-sustainable-by-design approach, this technology combines biocompatible components, nanometric coating for minimal material use, and a simple syringe-based delivery device, offering a scalable, antibiotic-free strategy for wound care and medical device infection prevention. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=173 HEIGHT=200 SRC="FIGDIR/small/717441v1_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@49381aorg.highwire.dtl.DTLVardef@1023e64org.highwire.dtl.DTLVardef@4e282aorg.highwire.dtl.DTLVardef@12eeae4_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2026

Developing Potent and Selective TBK1 Molecular Glue Degraders for Cancer Immunotherapy

Immune checkpoint blockade (ICB) has transformed cancer therapy across multiple tumour types, yet primary and acquired resistance remain major barriers to durable benefit. TANK-binding kinase 1 (TBK1) has emerged as an attractive target to enhance anti-tumour immunity, acting as a serine/threonine kinase that restrains immunogenic cell death and downstream immune activation. Here we report the discovery of a first-in-class TBK1 molecular glue degrader (MGD), CCT412020, identified through high-throughput proteomics screening of a next-generation molecular glue library. CCT412020 induces rapid, potent and selective TBK1 degradation across a panel of breast cancer cell lines. A cryo-EM structure of CCT412020 in complex with CRBN/{Delta}BPB-DDB1 and TBK1-homodimer reveals an unexpected binding mode that bypasses the canonical G-loop and instead engages an unconventional site at the TBK1 homodimer interface. Functionally, TBK1 loss via CCT412020 sensitises tumour cells to TNF- and interferon-driven responses and reduced viability across a broad range of cancer cell lines. Together, these findings establish CCT412020 as a mechanistically distinct TBK1 degrader and provide a framework for developing TBK1-targeted degraders as immunomodulatory anti-cancer agents to overcome ICB resistance.

cancer biology↗

bioRxiv2024

RIPK1 is essential for Herpes Simplex Virus-triggered ZBP1-dependent necroptosis in human cells

Necroptosis initiated by the host sensor Z-NA Binding Protein-1 (ZBP1) is essential for host defense against a growing number of viruses, including Herpes Simplex Virus-1 (HSV-1). Studies with HSV-1 and other necroptogenic stimuli in murine settings have suggested that ZBP1 triggers necroptosis by directly complexing with the kinase RIPK3. Whether this is also the case in human cells, or whether additional co-factors are needed for ZBP1-mediated necroptosis, is unclear. Here, we show that ZBP1-induced necroptosis in human cells requires RIPK1. We have found that RIPK1 is essential for forming a stable and functional ZBP1-RIPK3 complex in human cells, but is dispensable for the formation of the equivalent murine complex. The RIP Homology Interaction Motif (RHIM) in RIPK3 is responsible for this difference between the two species, because replacing the RHIM in human RIPK3 with the RHIM from murine RIPK3 is sufficient to overcome the requirement for RIPK1 in human cells. These observations describe a critical mechanistic difference between mice and humans in how ZBP1 engages in necroptosis, with important implications for treating human diseases.

cell biology↗

bioRxiv2024

Kinases in motion: impact of protein and small molecule interactions on kinase conformations

Protein kinases act as central molecular switches in the control of cellular functions. Alterations in the regulation and function of protein kinases may provoke diseases including cancer. In this study we investigate the conformational states of such disease-associated kinases using the high sensitivity of the Kinase Conformation (KinCon)-reporter system. We [fi]rst track BRAF-kinase activity conformation changes upon melanoma drug binding. Second, we also use the KinCon reporter technology to examine the impact of regulatory protein interactions on LKB1-kinase tumor suppressor functions. Third, we explore the conformational dynamics of RIP-kinases in response to TNF-pathway activation and small molecule interactions. Finally, we show that CDK4/6 interactions with regulatory proteins alter conformations which remain unaffected in the presence of clinically applied inhibitors. Apart from its predictive value, the KinCon technology helps to identify cellular factors that impact drug efficacies. The understanding of the structural dynamics of full-length protein kinases when interacting with small molecule inhibitors or regulatory proteins is crucial for designing more effective therapeutic strategies.

biochemistry↗

bioRxiv2023

PARP inhibitors enhance reovirus-mediated cell killing through the death-inducing signaling complex (DISC) with an associated NF-kappa B-regulated immune response.

Oncolytic Reovirus type 3 Dearing (RT3D), is a naturally occurring double-stranded (ds) RNA virus that is under development as an oncolytic immunotherapy We used an unbiased high-throughput cytotoxicity screen of different targeted therapeutic agents with the aim of identifying potential drug-viral sensitizers to enhance RT3D tumour killing. Talazoparib, a clinical poly(ADP)-ribose polymerase 1 (PARP-1) inhibitor, was identified as a top hit and found to cause profound sensitisation to RT3D. This effect was not seen with other classes of oncolytic virus and was not mediated by enhanced viral replication or PARP inhibitor-related effects on the DNA damage response. RT3D interacts with retinoic acid-induced gene-1 (RIG-I) and activates PARP-1, with consequent PARylation of components of the extrinsic apoptosis pathway. Pharmacological and genetic inhibition of PARP-1 abrogates this PARylation and increases levels of extrinsic apoptosis, NF-kB signalling and pro-inflammatory cell death. Direct interaction between PARP-1 and RIG-I following RT3D/talazoparib treatment is a key factor in activating downstream signaling pathways that lead to IFN-{beta} and TNF-/TRAIL production which, in turn, amplify the therapeutic effect through positive feedback. Critically, it was possible to phenocopy the effect of RT3D through the use of non-viral ds-RNA therapy and RIG-I agonism. In in vivo studies, we demonstrated profound combinatorial efficacy of RT3D and talazoparib in human A375 melanoma in immunodeficient mice. More impressively, in immunocompetent mouse models of 4434 murine melanoma, we achieved 100% tumour control and protection from subsequent tumour rechallenge with the combination regimen. Correlative immunophenotyping confirmed significant innate and adaptive immune activation with the combination of RT3D and PARP inhibition. Taken together, these data provide a clear line of sight to clinical translation of combined regimens of PARP inhibition or ds-RNA agonism, with either viral or non-viral agents, in tumour types beyond the relatively narrow confines of current licensed indications for PARP inhibition.

cancer biology↗

bioRxiv2023

PI-(3,5)P2-mediated oligomerization of the endosomal sodium/proton exchanger NHE9

Na+/H+ exchangers are found in all cells to regulate intracellular pH, sodium levels and cell volume. Na+/H+ exchangers are physiological homodimers that operate by an elevator alternating-access mechanism. While the structure of the core ion translocation domain is fairly conserved, the scaffold domain and oligomerization show larger structural variation. The Na+/H+ exchanger NhaA from E. coli has a weak oligomerization interface mediated by a {beta}-hairpin domain and homodimerization was shown to be dependent of the lipid cardiolipin. Organellar Na+/H+ exchangers NHE6, NHE7 and NHE9 are likewise predicted to contain {beta}-hairpin domains and a recent analysis of horse NHE9 indicated that the lipid PIP2 binds at the dimerization interface. Despite predicted lipid-mediated oligomerization, their structural validation has been lacking. Here, we report cryo-EM structures of E. coli NhaA and horse NHE9 with the coordination of cardiolipin and PI(3,5)P2 binding at the dimer interface, respectively. Cell based assays confirms that NHE9 is inactive at the plasma membrane and thermal-shift assays, solid-supported membrane (SSM) electrophysiology and MD simulations, corroborates that NHE9 specifically binds the endosomal PI(3,5)P2 lipid, which stabilizes the homodimer and enhances activity. Taken together, we propose specific lipids regulate Na+/H+ exchange activity by stabilizing oligomerization and stimulating Na+ binding under lipid-specific cues.

biochemistry↗

bioRxiv2022

Cleavage of cFLIP restrains cell death during viral infection and tissue injury and favors tissue repair

Cell death coordinates repair programs following pathogen attack and tissue injury. However, aberrant cell death can interfere with such programs and cause organ failure. cFLIP is a crucial regulator of cell death and a substrate of Caspase-8. Yet, the physiological role of cFLIP cleavage by Caspase-8 remains elusive. Here, we discovered an essential role for cFLIP cleavage in restraining cell death in different pathophysiological scenarios. Mice expressing a cleavage-resistant cFLIP mutant, CflipD377A, exhibited increased sensitivity to SARS-CoV-induced lethality, impaired skin wound healing and increased tissue damage caused by Sharpin deficiency. In vitro, abrogation of cFLIP cleavage sensitizes cells to TNF-induced necroptosis and apoptosis by favoring complex-II formation. Mechanistically, the cell death-sensitizing effect of the D377A mutation depends on Gln(Q)469. These results reveal a crucial role for cFLIP cleavage in controlling the amplitude of cell death responses occurring upon tissue stress, to ensure the execution of repair programs.

cell biology↗

bioRxiv2022

CDK4/6 inhibition and dsRNA sensor agonism co-operate to enhance anti-cancer effects through ER stress and immune modulation of tumour cells

Cytoplasmic pattern recognition receptors (PRRs) for double-stranded RNA (RIG-I/MDA5) are key mediators of anti-viral responses. PRR agonists, such as dsRNA oncolytic Reovirus type 3 Dearing (Rt3D), potently activate RNA sensors. We used an unbiased cytotoxicity screen to reveal synergistic drug-virotherapy combinations and found potent effects of Rt3D combined with the CDK4/6 inhibitor, palbociclib. The combination augmented oncolytic virus-induced endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and the expression and activation/signaling of RNA sensors. Combined Rt3D-palbociclib treatment potently increased interferon production and signaling, and knockdown studies implicated key UPR proteins and the RNA sensor, RIG-I, as essential to the phenotype observed. Further experiments, using canonical RIG-I agonists and an ER stress inducer, thapsigargin, confirmed cross-talk between RNA sensing and ER stress pathways that augmented cancer cell death and interferon production. Combined Rt3D-palbociclib also increased innate immune activation within tumour cells and IFN-induced HLA expression. Analysis of the immunopeptidome revealed changes to HLA-captured peptides with Rt3D-palbociclib, including altered expression of peptides from cancer/testis antigens (CTA) and endogenous retroviral elements (ERVs). Our findings highlight cross-talk between UPR signaling and RNA-mediated PRR activation as a means of enhancing anti-cancer efficacy with potential pro-immunogenic consequences. This has implications for future clinical development of PRR agonists and oncolytic viruses, and broadens the therapeutic remit of CDK4/6 inhibitors to include roles as both ER stress and dsRNA PRR sensitizers.

cancer biology↗

bioRxiv2021

Novel biochemical, structural and systems insights into inflammatory signaling revealed by contextual interaction proteomics

Protein-protein interactions (PPI) represent the main mode of the proteome organization in the cell. In the last decade, several large-scale representations of PPI networks have captured generic aspects of the functional organization of network components, but mostly lack the context of cellular states. However, the generation of contextual representations of PPI networks is essential for structural and systems-level modeling of biological processes and remains an unsolved challenge. In this study we describe an integrated experimental/computational strategy to achieve a contextualized modeling of PPI. This strategy defines the composition, stoichiometry, spatio-temporal organization and cellular requirements for the formation of target assemblies. We used this approach to generate an integrated model of the formation principles and architecture of a large signalosome, the TNF-receptor signaling complex (TNF-RSC). Overall, we show that the integration of systems- and structure-level information provides a generic, largely unexplored link between the modular proteome and cellular function. Significance StatementIn this work, we propose a critical shift in the way we analyze, and think the study of, protein-protein interactions (PPI), and present an experimental and computational framework to model them in the cellular context. We applied this framework to the signalosome tumor necrosis factor receptor signaling complex (TNF-RSC), and generated an integrated model of its formation and architecture that provides new insights and resolved controversies regarding its organization and regulation. To achieve a contextual modelling of PPIs, we first optimized and developed, and then combined, approaches to map the composition of a target complex, its absolute stoichiometry, its spatial organization and assembly/disassembly dynamics, its temporal dependence on signaling, and its reliance on cellular resources.

systems biology↗

bioRxiv2020

drICE restrains DIAP2-mediated inflammatory signalling and intestinal inflammation

The Drosophila IAP protein, DIAP2, is a key mediator of NF-κB signalling and is required for immune activation, both locally in the intestinal epithelia and during systemic, fat body-induced responses. We have found that transgenic expression of DIAP2 induces inflammation in the intestine, but not in the fat body, indicating a need for regulating DIAP2 in microbiotic environments. We describe the Drosophila caspase drICE, a known interaction partner of DIAP2, as a regulator of DIAP2 and NF-κB signalling in the intestinal epithelium. drICE acts by cleaving, and interfering with DIAP2’s ability to ubiquitinate and, thereby, activate mediators of the NF-κB pathway. The drICE-cleaved form of DIAP2 is, moreover, unable to induce inflammation during basal conditions in the intestine. Interestingly, cleavage of DIAP2 does not interfere with pathogen-induced signalling, suggesting that drICE protects from immune responses induced by resident microbes. Accordingly, the negative regulatory effect of drICE is lost when rearing flies axenic. Hence, we show that drICE halts unwanted inflammatory signalling in the intestine by forming an inhibitory complex with DIAP2, interfering with the ability of DIAP2 to induce downstream signalling and NF-κB target gene activation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2020

Myc supercompetitor cells exploit the NMDA receptor to subdue their wild-type neighbours via cell competition

Myc is a major driver of cell growth in many cancers, but direct inhibition of Mycs oncogenic activity has been challenging. Interactions between wild-type and Myc-expressing cells cause Myc cells to acquire supercompetitor behaviour that increases their fitness and enables them to overtake the tissue by killing their wild-type neighbours through TNF-induced cell death during a process called cell competition. Here we report that the competitive behaviour of Myc, RasV12 cells, and normal epithelial cells, critically depends on the NMDA receptor. Myc cells upregulate NMDAR2 (NR2) to gain supercompetitor status and subdue their wild-type neighbours. Pharmacological inhibition or genetic depletion of NR2 changes the supercompetitor status of oncogenic Myc or RasV12 clones into superlosers, resulting in their elimination via cell competition by wild-type neighbours in a TNF-dependent manner. Our data demonstrate that that the NMDA receptor (NMDAR) determines cellular fitness during cell competition, and can be targeted to change the fitness landscape of supercompetitive Myc and RasV12 clones, converting them into superlosers.

cell biology↗

bioRxiv2019

DRP1-mediated regulation of mitochondrial dynamics determines the apoptotic response upon embryonic differentiation.

The changes that drive differentiation create a large potential for the emergence of abnormal cells that need to be removed before they contribute to further development or the germline. This removal is in part achieved by cells becoming hypersensitive to death upon exit of naive pluripotency. What causes this change in apoptotic response is unknown. Here we identify that it is controlled by the regulator of mitochondrial dynamics DRP1. We show that in mouse, naive pluripotent cells have fragmented mitochondria due to high DRP1-mediated fission, but upon differentiation, DRP1 activity decreases, inducing mitochondria to fuse and form complex networks. We demonstrate that this decrease in DRP1 activity lowers the apoptotic threshold, as mutation of DRP1 increases the sensitivity to cell death and its over-expression protects against apoptosis. Together, our findings highlight how regulation of mitochondrial dynamics allows cells to adapt their apoptotic response to the changing environment of differentiation.

developmental biology↗