Summary
Filamentous fungi are powerful producers of hydrolytic enzymes for the deconstruction of plant cell wall polysaccharides. However, the central question of how these sugars are perceived in the context of the complex cell wall matrix remains largely elusive. To address this question in a systematic fashion we performed an extensive comparative systems analysis of how the model filamentous fungus Neurospora crassa responds to the three main cell wall polysaccharides: pectin, hemicellulose and cellulose. We found the pectic response to be largely independent of the cellulolytic one with some overlap to hemicellulose, and in its extent surprisingly high, suggesting advantages for the fungus beyond being a mere carbon source. Our approach furthermore allowed us to identify carbon source-specific adaptations, such as the induction of the unfolded protein response on cellulose, and a commonly induced set of 29 genes likely involved in carbon scouting. Moreover, by hierarchical clustering we generated a co-expression matrix useful for the discovery of new components involved in polysaccharide utilization. This is exemplified by the identification of lat-1, which we demonstrate to encode for the physiologically relevant arabinose transporter in Neurospora. The analyses presented here are an important step towards understanding fungal degradation processes of complex biomass.
Although chemotherapeutic agents and molecular medicine are pillars of successful treatment of cancer, the recent clinical development of immunotherapies shows compelling promise in the treatment of many tumor types. In hematologic malignancies, immunotherapies centered upon cytolytic T lymphocytes as drugs, such as chimeric antigen receptor (CAR)-T cells and bispecific T-cell engagers (BiTE) or antibodies (BsAb), are central among these advances. BiTEs and BsAbs are "offthe-shelf" drug therapies that circumvent the need for timeconsuming and expensive ex vivo manipulation of patient cells. These agents often consist of monoclonal antibodies or singlechain variable fragments in the case of BiTEs, engineered with one binding site directed toward a tumor-specific antigen and another against the T-lymphocyte activating receptor CD3epsilon. BsAbs redirect T cells to kill tumors by bringing them into physical contact and activating secretion of cytotoxic molecules (1). Due to their novel mode of action, BsAb therapeutics may provide an effective option for all patients, including those with cytogenetically high-risk or heavily pretreated disease that renders them more resistant to standard-of-care therapy.
Glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) and GITR ligand (GITRL) are members of the tumor necrosis superfamily that play a role in immune cell signaling, activation, and survival. GITR is a therapeutic target for directly activating effector CD4 and CD8 T cells, or depleting GITR-expressing regulatory T cells (Tregs), thereby promoting anti-tumor immune responses. GITR activation through its native ligand is important for understanding immune signaling, but GITR structure has not been reported. Here we present structures of human and mouse GITR receptors bound to their cognate ligands. Both species share a receptor–ligand interface and receptor–receptor interface; the unique C-terminal receptor–receptor enables higher order structures on the membrane. Human GITR–GITRL has potential to form a hexameric network of membrane complexes, while murine GITR–GITRL complex forms a linear chain due to dimeric interactions. Mutations at the receptor–receptor interface in human GITR reduce cell signaling with in vitro ligand binding assays and minimize higher order membrane structures when bound by fluorescently labeled ligand in cell imaging experiments.
The development of antibody therapeutics relies on animal models that accurately recapitulate disease biology. Syngeneic mouse models are increasingly used with new molecules to capture the biology of complex cancers and disease states, and to provide insight into the role of the immune system. The establishment of syngeneic mouse models requires the ability to generate surrogate mouse counterparts to antibodies designed for humans. In the field of bispecific antibodies, there remains a dearth of technologies available to generate native IgG-like mouse bispecific antibodies. Thus, we engineered a simple co-expression system for one-step purification of intact mouse IgG1 and IgG2a bispecific antibodies from any antibody pair. We demonstrated proof of concept with CD3/CD20 bispecific antibodies, which highlighted both the quality and efficacy of materials generated by this technology.
Bispecific
antibodies (BsAbs), with a unique mechanism of recognizing
two different epitopes or antigens, have shown potential in various
therapeutic areas. Molecular characterization of BsAbs’ epitopes
not only allows for detailed understanding of their mechanism of actions
but also guides the design and selection of drug candidate molecules.
In this study, we illustrate the practical utility of an integrated
approach, including size exclusion chromatography with multiangle
light scattering and native mass spectrometry (MS) for the biophysical
characterization of complex formation of a BsAb with two target antigens,
cluster of differentiation 3 (CD3) and B-cell maturation antigen (BCMA).
MS-based protein footprinting strategies, including hydrogen/deuterium
exchange MS, fast photochemical oxidation of proteins, and carboxyl
group footprinting with glycine ethyl ester, were further applied
to determine BsAb’s binding epitopes. This combination approach
provides molecular details on the binding mechanisms of BsAb to the
two distinct antigens with rapid output and high resolution.
T-cell engagers (TCEs) are a growing class of biotherapeutics being investigated in the clinic for treatment of a variety of hematological and solid tumor indications. However, preclinical evaluation of TCEs in vivo has been mostly limited to xenograft tumor models in human T-cell reconstituted immunodeficient mice, which have a number of limitations. To explore the efficacy of human TCEs in fully immunocompetent hosts, we developed a knock-in mouse model (hCD3E-epi) in which a 5-residue N-terminal fragment of murine CD3-epsilon was replaced with an 11-residue stretch from the human sequence that encodes for a common epitope recognized by anti-human CD3E antibodies in the clinic. T cells from hCD3E-epi mice underwent normal thymic development and could be efficiently activated upon crosslinking of the T-cell receptor with anti-human CD3E antibodies in vitro. Furthermore, a TCE targeting human CD3E and murine CD20 induced robust T-cell redirected killing of murine CD20-positive B cells in ex vivo hCD3E-epi splenocyte cultures, and also depleted nearly 100% of peripheral B cells for up to 7 days following in vivo administration. These results highlight the utility of this novel mouse model for exploring the efficacy of human TCEs in vivo, and suggest a useful tool for evaluating TCEs in combination with immuno-oncology/non-immuno-oncology agents against heme and solid tumor targets in hosts with a fully intact immune system.
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