Project description:Recent exon sequencing studies of human tumors have revealed that subunits of mSWI/SNF or BAF complexes are mutated in more than 20% of human malignancies, yet the mechanisms involved in tumor suppression is unclear. BAF chromatin remodeling complexes are polymorphic assemblies that use energy provided by ATP hydrolysis to regulate transcription through the control of chromatin structure and the placement of Polycomb (PcG) across the genome. Several proteins dedicated to this large multi-subunit complex, including SMARCA4 (BRG1) and BAF250A (ARID1A), are mutated at frequencies similar to that of many recognized tumor suppressors. In particular, the core ATPase BRG1 is mutated in 5-10% of childhood medulloblastoma (MB) and greater than 15% of Burkitt's Lymphoma (BL). Here we find a novel function of BAF complexes in decatenating newly replicated sister chromatids, which is necessary for proper chromosome segregation during mitosis. We find that deletion of Brg1, as well as the expression of Brg1 point mutants identified in human tumors leads to anaphase bridge formation (sister chromatids linked by catenated strands of DNA), and a G2/M phase block characteristic of the decatenation checkpoint. Endogenous BAF complexes directly interact with endogenous TopoIIα through BAF250a and are required for TopoIIα binding to about 12,000 sites over the genome. Our results indicate that TopoIIα’s chromatin binding is dependent on the ATPase activity of Brg1, which is compromised in oncogenic Brg1 mutants. These studies indicate that the ability of TopoIIα to prevent DNA entanglement at mitosis requires BAF complexes and suggest that this activity contributes to the role of BAF subunits as tumor suppressors. Examination of sites of TopoIIa activity in WT and Brg1-/- ES cells as defined by TopoIIa-DNA covalent adducts formed in the presence of etoposide
Project description:Tumor necrosis factor receptor 2 (TNFR2), a membrane-bound tumor necrosis factor receptor expressed by regulatory T cells (Tregs), participates in Treg proliferation. Although a specific TNFR2 pathway has been reported, the signaling mechanism has not been completely elucidated. This study sought to clarify TNFR2 signaling in human Tregs using amplicon sequencing and single-cell RNA-sequencing to assess Tregs treated with a TNFR2 agonist antibody. Pathway enrichment analysis based on differentially expressed genes highlighted tumor necrosis factor α signaling via nuclear factor-kappa B, interleukin-2 signal transducer and activator of transcription 5 signaling, interferon-γ response, and cell proliferation-related pathways in Tregs after TNFR2 activation. TNFR2-high Treg-focused analysis found that these pathways were fully activated in cancer Tregs, showing high TNFR2 expression. Collectively, these findings suggest that TNFR2 orchestrates multiple pathways in cancer Tregs, which could help cancer cells escape immune surveillance, making TNFR2 signaling a potential anticancer therapy target.
Project description:Tumor Necrosis Factor Alpha is a known pro-inflammatory cytokine that plays a key role in the pathogenesis of rheumatoid arthritis. Anti-cytokine therapies targeting Tumor Necrosis Factor Alpha have greatly succeeded in treating rheumatoid arthritis in many patients. Despite these developments, many of the mechanisms of Tumor Necrosis Factor Alpha action have yet to be uncovered. In this study, we incubated PBMCs from healthy donors and rheumatoid arthritis patients with Tumor Necrosis Factor Alpha and then performed their single-cell multi-omics analysis via BD Rhapsody. We have observed that Classical Monocytes have responded to the Tumor Necrosis Factor Alpha stimulation the most and that there was an activational threshold for such response that was dependent on the TNFR2 protein expression level. The profiling of TNFR2 protein expression level on immune cell populations can be a good predictive factor for the assessment of their activation by Tumor Necrosis Factor Alpha.
Project description:Tumor necrosis factor receptor 2 (TNFR2), a membrane-bound tumor necrosis factor receptor expressed by regulatory T cells (Tregs), participates in Treg proliferation. Although a specific TNFR2 pathway has been reported, the signaling mechanism has not been completely elucidated. This study sought to clarify TNFR2 signaling in human Tregs using amplicon sequencing and single-cell RNA-sequencing to assess Tregs treated with a TNFR2 agonist antibody. Pathway enrichment analysis based on differentially expressed genes highlighted tumor necrosis factor α signaling via nuclear factor-kappa B, interleukin-2 signal transducer and activator of transcription 5 signaling, interferon-γ response, and cell proliferation-related pathways in Tregs after TNFR2 activation. TNFR2-high Treg-focused analysis found that these pathways were fully activated in cancer Tregs, showing high TNFR2 expression. Collectively, these findings suggest that TNFR2 orchestrates multiple pathways in cancer Tregs, which could help cancer cells escape immune surveillance, making TNFR2 signaling a potential anticancer therapy target.
Project description:The inability to selectively deliver therapeutic RNAs within target cells currently hinders the development of novel treatments for cancer and other disorders. Here, we report that a tumor-targeting, cell-penetrating, and RNA-binding antibody, TMAB3, can form non-covalent antibody/RNA complexes that mediate highly specific and functional delivery of RNAs into tumors. We observed a robust anti-tumor efficacy of systemically administered 3p-hpRNA, an agonist of viral RNA sensor RIG-I, in complex with TMAB3 in animal models of pancreatic cancer, medulloblastoma, and melanoma. In pancreatic cancer models, treatment with TMAB3/3p-hpRNA tripled animal survival, decreased tumor growth, and specifically targeted malignant cells, with a 1500-fold difference in RNA delivery into tumor cells versus non-malignant cells within the tumor mass. Single-cell RNA-sequencing (scRNA-seq) and flow cytometry demonstrated that TMAB3/3p-hpRNA treatment elicited anti-tumoral immune responses against tumor cells. These studies establish that TMAB3/3p-hpRNA complexes can effectively deliver RNA payloads to malignant cells in hard-to-treat tumors to achieve anti-tumor efficacy, providing an antibody-based platform to advance RNA therapies for cancer.
Project description:Antibody-mediated rejection (AMR) accounts for >50% of kidney allograft losses. AMR is caused by donor-specific antibodies (DSA) against HLA and non-HLA antigens in the glomeruli and the tubulointerstitium, which together with high interferon gamma (IFNɣ) and tumor necrosis factor-alpha (TNFα), trigger graft injury. Unfortunately, the mechanisms governing cell-specific injury in AMR remain unclear. We studied 30 for-cause kidney biopsies with early AMR, acute cellular rejection or acute tubular necrosis (‘non-AMR’). We laser-captured microdissected glomeruli and tubulointerstitium and subjected them to unbiased proteome analysis. 120/2026 glomerular and 180/2399 tubulointerstitial proteins were significantly differentially expressed in AMR vs. non-AMR biopsies (p<0.05). Basement membrane and extracellular matrix (ECM) proteins were significantly decreased in both AMR compartments. We verified decreased glomerular and tubulointerstitial LAMC1 expression, and decreased glomerular NPHS1 and PTPRO expression in AMR. Cathepsin-V (CTSV) was predicted to cleave ECM-proteins in the AMR glomeruli, and CTSL, CTSS and LGMN in the tubulointerstitium. We identified galectin-1, an immunomodulatory protein upregulated in AMR glomeruli and linked to the ECM. Anti-HLA class-I antibodies significantly increased CTSV expression, and galectin-1 expression and secretion, in human glomerular endothelial cells. We also studied glutathione S-transferase omega-1 (GSTO1), an ECM-modifying enzyme, increased in the AMR tubulointerstitium. GSTO1 expression was significantly increased in TNFα-treated proximal tubular epithelial cells. IFNɣ and TNFα significantly increased CTSS and LGMN expression in these cells. Basement membranes are often remodeled in chronic AMR, and we demonstrated that this remodeling begins early in glomeruli and tubulointerstitium. Targeting ECM-remodeling in AMR may represent a new therapeutic opportunity.
Project description:The ability to leverage antibodies to agonize disease relevant biological pathways has the potential to unlock new drug targets for clinical investigation. While antibodies have been successful as antagonists, immune mediators, and targeting agents, they are not readily effective at recapitulating the biological activity of natural ligands. Among the important determinants of antibody agonist activity is the geometry of target receptor engagement. Herein, we describe a novel engineering approach inspired by a naturally occurring Fab-Fab homotypic interaction that constrains IgG in a unique i-shaped conformation. i-shaped antibody (iAb) engineering enables potent intrinsic agonism of five tumor necrosis factor receptor superfamily (TNFRSF) targets. When applied to bispecific antibodies against the heterodimeric IL-2 receptor pair, constrained bispecific IgG formats recapitulate IL-2 agonist activity. Thus, iAb engineering represents a new tool to tune agonist antibody function and this work provides a framework for the development of intrinsic antibody agonists with the potential for generalization across broad receptor classes.
Project description:Targeting cellular RNA by small molecules has come to the forefront of biotechnology and holds great promise for therapeutic use. Strategies to identify, validate and optimize these molecules are essential, but are still lacking in some aspects. In particular, the site-specific covalent labeling and modification of RNA in living cells poses many challenges. Here, we describe a general structure-guided approach to engineer non-covalent RNA aptamer–ligand complexes into their covalent counterparts using a molecular tether. The key is to modify the native ligand with an electrophilic handle that allows it to react specifically with a guanine at the RNA ligand binding site. We show that site-specific cross-linking between ligand and RNA is achieved in mammalian cells upon transfection of a genetically encoded version of the preQ1-I riboswitch aptamer. Further, we showcase the versatility of the tether by engineering the first covalent fluorescent light-up aptamer (coFLAP) out of the non-covalent Pepper FLAP. The coPepper system maintains strong fluorescence in live-cell imaging even after repeated washing. Thus, any background signal arising from unspecific fluorophore accumulation in the cell can be eliminated. In addition, we generated a bifunctional Pepper ligand containing a second handle for bioorthogonal chemistry to allow for easily traceable and efficient pulldown of the covalently linked target RNA. Finally, we provide evidence for the suitability of this tethering strategy for specific drug targeting. Taken together, our results show that functionalized ligands generated by rational design can cross-link site-specifically with target RNAs in cells, and hence, open up a wide range of applications in RNA biology that require irreversible small molecule binding.
Project description:Background: OX40 (CD134) is a co-stimulatory molecule of the tumor necrosis factor receptor (TNFR) superfamily, that is currently investigated as a target for cancer immunotherapy. However, despite promising results in murine tumor models, the clinical efficacy of agonistic αOX40 antibodies in treatment of cancer patients has fallen short of the high expectation in earlier stage trials. Methods: Using lymphocytes from resected tumor, tumor-free tissue and PBMC of 4 hepatocellular and colorectal cancer patients, we performed RNA-Seq to evaluate OX40-mediated transcriptional changes in CD4+ and CD8+ human tumor-infiltrating lymphocytes (TILs). Results: The transcriptional landscape of CD4+ and CD8+ TILs shifted towards a pro-survival, inflammatory and chemotactic profile upon treatment with αOX40_v12.