About InVivoSIM anti-human PD-L1 (Atezolizumab Biosimilar) This non-therapeutic biosimilar antibody uses the same variable regions from the therapeutic antibody Atezolizumab making it ideal for research use. This Atezolizumab biosimilar reacts with human PD-L1 (programmed death ligand 1) also known as B7-H1 or CD274. PD-L1 is a 40 kDa type I transmembrane protein that belongs to the B7 family of the Ig superfamily. PD-L1 is expressed on T lymphocytes, B lymphocytes, NK cells, dendritic cells, as well as IFNγ stimulated monocytes, epithelial cells and endothelial cells. PD-L1 binds to its receptor, PD-1, found on CD4 and CD8 thymocytes as well as activated T and B lymphocytes and myeloid cells. Engagement of PD-L1 with PD-1 leads to inhibition of TCR-mediated T cell proliferation and cytokine production. PD-L1 is thought to play an important role in tumor immune evasion. Induced PD-L1 expression is common in many tumors and results in increased resistance of tumor cells to CD8 T cell mediated lysis. Atezolizumab blocks the interaction of PD-L1 with PD-1 and CD80. InVivoSIM anti-human PD-L1 (Atezolizumab Biosimilar) Specifications IsotypeHuman IgG1 Recommended Isotype Control(s)RecombiMAb human IgG1 (N297A) isotype control, anti-hen egg lysozyme Recommended Dilution BufferInVivoPure pH 7.0 Dilution Buffer ImmunogenNot available or unknown Reported ApplicationsFlow Cytometry Western Blot FormulationPBS, pH 7.0 Contains no stabilizers or preservatives Endotoxin<1EU/mg (<0.001EU/μg) Determined by LAL gel clotting assay Aggregation<5% Determined by SEC Purity>95% Determined by SDS-PAGE Sterility0.2 μm filtration ProductionPurified from cell culture supernatant in an animal-free facility PurificationProtein A RRIDAB_2894730 Molecular Weight150 kDa StorageThe antibody solution should be stored at the stock concentration at 4°C. Do not freeze. Application ReferencesInVivoSIM anti-human PD-L1 (Atezolizumab Biosimilar) (CLONE: Atezolizumab)Zhao Y, Caron C, Chan YY, Lee CK, Xu X, Zhang J, Masubuchi T, Wu C, Bui JD, Hui E (2023). "cis-B7:CD28 interactions at invaginated synaptic membranes provide CD28 co-stimulation and promote CD8+ T cell function and anti-tumor immunity" Immunity 56(6):1187-1203.e12. PubMedB7 ligands (CD80 and CD86), expressed by professional antigen-presenting cells (APCs), activate the main co-stimulatory receptor CD28 on T cells in trans. However, in peripheral tissues, APCs expressing B7 ligands are relatively scarce. This raises the questions of whether and how CD28 co-stimulation occurs in peripheral tissues. Here, we report that CD8+ T cells displayed B7 ligands that interacted with CD28 in cis at membrane invaginations of the immunological synapse as a result of membrane remodeling driven by phosphoinositide-3-kinase (PI3K) and sorting-nexin-9 (SNX9). cis-B7:CD28 interactions triggered CD28 signaling through protein kinase C theta (PKCθ) and promoted CD8+ T cell survival, migration, and cytokine production. In mouse tumor models, loss of T cell-intrinsic cis-B7:CD28 interactions decreased intratumoral T cells and accelerated tumor growth. Thus, B7 ligands on CD8+ T cells can evoke cell-autonomous CD28 co-stimulation in cis in peripheral tissues, suggesting cis-signaling as a general mechanism for boosting T cell functionality.Sun R, Meng Z, Lee H, Offringa R, Niehrs C (2023). "ROTACs leverage signaling-incompetent R-spondin for targeted protein degradation" Cell Chem Biol 30(7):739-752.e8. PubMedProteolysis-targeting chimeras (PROTACs) are an emerging technology for therapeutic intervention, but options to target cell surface proteins and receptors remain limited. Here we introduce ROTACs, bispecific WNT- and BMP-signaling-disabled R-spondin (RSPO) chimeras, which leverage the specificity of these stem cell growth factors for ZNRF3/RNF43 E3 transmembrane ligases, to target degradation of transmembrane proteins. As a proof-of-concept, we targeted the immune checkpoint protein, programmed death ligand 1 (PD-L1), a prominent cancer therapeutic target, with a bispecific RSPO2 chimera, R2PD1. The R2PD1 chimeric protein binds to PD-L1 and at picomolar concentration induces its lysosomal degradation. In three melanoma cell lines, R2PD1 induced between 50 and 90% PD-L1 protein degradation. PD-L1 degradation was strictly dependent on ZNRF3/RNF43. Moreover, R2PD1 reactivates cytotoxic T cells and inhibits tumor cell proliferation more potently than Atezolizumab. We suggest that signaling-disabled ROTACs represent a paradigm to target cell surface proteins for degradation in a range of applications.
