Biology subjects

Luca, V. C.

Publications and source records attributed to Luca, V. C..

7 recordsLinked to original sources

bioRxiv2026

Dual stimulation of CD40 and 41BB pathways during ex-vivo TIL expansion enhances CD8+ T cell expansion

BackgroundTumor-infiltrating lymphocyte (TIL) therapy has demonstrated clinical efficacy in malignant melanoma; however, inefficient ex vivo expansion remains a major limitation. We previously showed that stimulation of tumor-infiltrating B cells via CD40-CD40L axis improves TIL expansion, and that direct activation of the 41BB-41BBL pathway on T cells enhances CD8 T cell outgrowth. We hypothesized that adding simultaneous targeting of both pathways would augment the growth and activity of CD8+ cytotoxic T cells. We conducted a study with the objective of determining the feasibility of dual stimulation with human tumors as justification for a Phase I trial. MethodsCD40L variants were generated by yeast display selection and evaluated for B cell binding and activation. The effects of CD40L variants on TIL expansion were evaluated using tumors derived from standard of care resections using fragment method. Based on these findings, a bi-specific molecule was designed and generated fusing a CD40L variant and 41BB to the N- and C-termini of a trimeric leucine zipper. The effects of the bi-specific molecule (termed CD40LEPC6-41BBL) on TIL expansion were evaluated in TIL cultures derived from lung tumor and melanoma fragments. TIL phenotypes were assessed by flow cytometry, including high-dimensional FlowSOM analysis, and tumor reactivity by autologous tumor co-culture assays. ResultsEach of our engineered CD40L variants bound B cells and induced CD80/CD86 expression at levels comparable to wild-type CD40L. Supplementation of TIL cultures with CD40L variants increased the success rate of TIL expansion compared to control. We then developed a bi-specific CD40LEPC6-41BBL molecule capable of binding to both B and T cells. Addition of CD40LEPC6-41BBL significantly increased total TIL yield and improved expansion success rates in both lung tumor and melanoma cultures. In particular, CD40LEPC6-41BBL promoted preferential expansion of CD8 T cells. High-dimensional analysis revealed enrichment of CD8 T cell clusters expressing CD39, CD69, TIM3, and CD56 in cultures supplemented with CD40LEPC6-41BBL. Furthermore, treated cultures displayed increased frequencies of CD27 CD4 T cells. Functional assessment suggested a trend toward enhanced tumor reactivity in melanoma-derived TIL products expanded with CD40LEPC6-41BBL. ConclusionsSimultaneous stimulation of CD40 and 41BB pathways using a novel bi-specific molecule resulted in qualitative and quantitative enhancement of TIL products. These findings support dual targeting of tumor-infiltrating B cells and T cells as a promising strategy to optimize TIL manufacturing for adoptive cell therapy in Phase I trials.

immunology↗

bioRxiv2024

Engineering synthetic agonists for targeted activation of Notch signaling

Notch signaling regulates cell fate decisions and has context-dependent tumorigenic or tumor suppressor functions. Although there are several classes of Notch inhibitors, the mechanical force requirement for Notch receptor activation has hindered attempts to generate soluble agonists. To address this problem, we engineered synthetic Notch agonist (SNAG) proteins by tethering affinity-matured Notch ligands to antibodies or cytokines that internalize their targets. This bispecific format enables SNAGs to "pull" on mechanosensitive Notch receptors, triggering their activation in the presence of a desired biomarker. We successfully developed SNAGs targeting six independent surface markers, including the tumor antigens PDL1, CD19, and HER2, and the immunostimulatory receptor CD40. SNAGs targeting CD40 increase expansion of central memory {gamma}{delta} T cells from peripheral blood, highlighting their potential to improve the phenotype and yield of low-abundance T cell subsets. These insights have broad implications for the pharmacological activation of mechanoreceptors and will expand our ability to modulate Notch signaling in biotechnology.

synthetic biology↗

bioRxiv2022

Notch engagement by Jag1 nanoscale clusters indicates a force-independent mode of activation

The Notch signaling pathway is a cell-cell communication system with fundamental roles in embryonic development and the nervous system. The model of Notch receptor activation that is currently most accepted, involves a force-induced conformation change at the negative regulatory region of the receptor, the subsequent recruitment of ADAM metalloproteases and a cleavage cascade that releases the Notch intracellular domain. Here, we define conditions that enable force-independent Notch activation through the formation of soluble, long-lived, multivalent ligand-receptor complexes. To investigate how ligand valency affects activation of Notch receptors, we treated iPSc-derived neuroepithelial stem-like (lt-NES) cells with different spatially defined, molecularly precise ligand nanopatterns on DNA origami nanostructures. Our data indicate that Notch signaling is activated via stimulation with multivalent clusters of the ligand Jag1, and even multivalent chimeric structures where some Jag1 proteins are replaced by other binders that do not target Notch. The findings are corroborated by systematic elimination, through experimental control, of several confounding factors that potentially could generate forces, including electrostatic interactions, endocytosis and non-specific binding. Taken together, our data suggest a model where Jag1 ligands are able to activate Notch receptors upon prolonged binding, which subsequently triggers downstream signaling in a force independent manner. These findings reveal a distinct mode of activation of Notch and could lay the foundation for the development of soluble Notch agonists that currently remain elusive.

cell biology↗

bioRxiv2022

Functional Comparison Between Endogenous and Synthetic Notch Systems

The Notch pathway converts receptor-ligand interactions at the cell surface into a transcriptional response in the receiver cell. In recent years, synthetic Notch systems (SynNotch) that respond to different inputs and transduce different transcriptional responses have been engineered. One class of synNotch systems uses antibody-antigen interactions at the cell surface to induce the proteolytic cleavage cascade of the endogenous Notch autoregulatory core and the consequent release of a synNotch intracellular domain (ICD), converting surface antigen detection into a cellular response. However, whereas the activation of endogenous Notch requires ubiquitylation and subsequent endocytosis of the ligand ICD, these synNotch systems do not seem to have such a requirement because the synNotch ligands completely lack an ICD. This observation raises questions about existing models for the Notch activation mechanism. Here, we test how different structural and biochemical factors affect the dependence of endogenous and synthetic Notch activation on ligand ICD. We compare the behavior of antibody-antigen synNotch (aa-synNotch) to that of endogenous Notch, and to a synNotch system that uses induced FKBP-FRB dimerization with rapamycin (ff-synNotch), which still requires a ligand ICD. We found that differences in receptor-ligand affinity, in the identity of the transmembrane domain, or in the presence or absence of extracellular EGF repeats cannot explain the differences in ligand ICD requirement that distinguishes aa-synNotch from endogenous Notch or ff-synNotch. These findings suggest that the aa-SynNotch systems bypass the ligand ICD requirement because antigen-antibody pairs are able to promote other adhesive cell-cell interactions that provide the mechanical tension needed for ligand activation.

molecular biology↗

bioRxiv2022

An affinity-matured DLL4 ligand for broad-spectrum activation and inhibition of Notch signaling

The Notch pathway regulates cell fate decisions and is an emerging target for regenerative and cancer therapies. Recombinant Notch ligands are attractive candidates for modulating Notch signaling; however, their intrinsically low receptor-binding affinity restricts their utility in biomedical applications. To overcome this limitation, we evolved variants of the ligand Delta-like 4 (DLL4) with enhanced affinity and cross-reactivity. A consensus variant with maximized binding affinity, DeltaMAX, engages human and murine Notch receptors with 500- to 1000-fold increased affinity compared to wild-type human DLL4. DeltaMAX also potently activates human Notch in plate-bound, bead-bound, and cellular formats. When administered as a soluble decoy, DeltaMAX inhibits Notch activation in response to either Delta-like (DLL) or Jagged (Jag) ligands, highlighting its utility as both an agonist and antagonist. Finally, we demonstrate that DeltaMAX stimulates increased proliferation and expression of effector mediators in primary activated human T cells. Taken together, our data defines DeltaMAX as a versatile biotechnological tool for broad-spectrum activation or inhibition of Notch signaling.

bioengineering↗

bioRxiv2020

Structural basis of bile acid receptor activation and Gs coupling

G protein-coupled bile acid receptor (GPBAR) is a membrane receptor that senses bile acids to regulate diverse functions through Gs activation. Here, we report the cryo-EM structures of GPBAR-Gs complexes stabilized by either high-affinity P395 or the semisynthesized bile acid derivative INT-777 at 3-[A] resolution. These structures revealed a large oval-shaped ligand pocket with several sporadic polar groups to accommodate the amphipathic cholic core of bile acids. A fingerprint of key residues recognizing diverse bile acids in the orthosteric site, a putative second bile acid binding site with allosteric properties and structural features contributing to bias property were identified through structural analysis and mutagenesis studies. Moreover, structural comparison of GPBAR with other GPCRs uncovered an atypical mode of receptor activation and G-protein- coupling, featuring a different set of key residues connecting the ligand binding pocket to the Gs coupling site, and a specific interaction motif localized in intracellular loop 3. Overall, our study not only provides unique structural features of GPBAR in bile acid recognition, allosteric effects and biased signaling, but also suggests that distinct allosteric connecting mechanisms between the ligand binding pocket and the G protein binding site exist in the GPCR superfamily.

biochemistry↗

bioRxiv2018

Surrogate R-spondin agonists for tissue-specific potentiation of Wnt signaling

Secreted R-spondin1-4 proteins (RSPO1-4) orchestrate stem cell renewal and tissue homeostasis by potentiating Wnt/{beta}-catenin signaling. RSPOs induce the turnover of negative Wnt regulators RNF43 and ZNRF3 through a process that requires RSPO interactions with either Leucine-rich repeat containing G-protein coupled receptors (LGRs) or heparin sulfate proteoglycans (HSPGs). Here, we describe the engineering of surrogate RSPOs that function independently of LGRs and HSPGs to enhance Wnt signaling on cell types expressing a target surface marker. These bispecific proteins were generated by fusing an RNF43- or ZNRF3-specific single chain antibody variable fragment (scFv) to the immune cytokine IL-2. Surrogate RSPOs mimic the function of natural RSPOs by crosslinking the extracellular domain (ECD) of RNF43 or ZNRF3 to the ECD of the IL-2 receptor CD25, which sequesters the complex and results in highly selective amplification of Wnt signaling on CD25+ cells. Furthermore, surrogate RSPOs were able substitute for wild type RSPO in a colon organoid growth assay when intestinal stem cells were transduced to express CD25. Our results provide proof-of-concept for a technology that may be adapted for use on a broad range of cell- or tissue-types and will open new avenues for the development of Wnt-based therapeutics for regenerative medicine.

molecular biology↗