Project description:Type I Interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I Interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce sustained STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling and resulted in efficient elimination of vesicular stomatitis virus (VSV) in a cell culture based viral infection model using MC57 cells stimulated with synthetic type IFN ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supporting this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.
Project description:Type I interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling. Moreover, replication of vesicular stomatitis virus (VSV) in a cell culture-based viral infection model using MC57 cells was significantly inhibited after stimulation with synthetic ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supports this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.
Project description:We used RNA sequencing to measure the transcriptomic consequences of transfecting cells with SSE mimetics (compared to scrambled controls).
Project description:BH3 mimetics are used as an efficient strategy to promote mitochondrial-dependent cell death in blood malignancies, including acute myeloid leukemia (AML). Venetoclax, a potent BCL2 antagonist, is used clinically in combination with hypomethylating agents for the treatment of AML, while various compounds targeting MCL1 are in clinical trials. Yet, drug resistance eventually ensues, highlighting the urgency to understand the underlying mechanisms. Our genome-wide CRISPR/Cas9 screens revealed that loss of mitophagy regulators sensitizes AML to BH3 mimetics. One such regulator is Mitofusin-2 (MFN2), a GTPase that controls mitochondrial dynamics and the degradation of damaged mitochondria through mitophagy. Resistance to BH3 mimetics is accompanied by alterations in mitochondrial morphology, enhanced mitochondria-endoplasmic reticulum interactions, and augmented mitophagy flux. MFN2 inactivation, using a novel small molecule inhibitor, and pharmacologic inhibition of mitophagy synergizes with BH3 mimetics. Overall, targeting of mitophagy along with BCL2-family members is a promising strategy to overcome drug resistance in AML.
Project description:TPO mimetics have been shown to activate TPO receptor, the downstream JAK-STAT pathway, and induce differentiation of hematopoietic stem cells into megakaryocytes. However, the action of these TPO mimetics is initiated by binding to the transmembrane domain of the TPO receptor, which is distinct from the binding site of the native ligand, TPO. To determine whether TPO mimetics can differentiate hematopoietic stem cells into the same megakaryocytes as native TPO does, we performed a microarray experiment to compare the globe gene expression in purified CD61+ cells derived from TPO or TPO mimetic treated CD34+ bone marrow cells. Keywords: Drug Treatment
Project description:Small molecular TPO mimetics, LGD-4665 and eltrombopag, were efficacious in stimulating the formation of CD41+ cells from human bone marrow CD34+ cells. To better understand the mechanism of action of TPO mimetics, a microarray study was performed to compare global gene expression in CD34+ cells induced by small molecular TPO mimetics eltrombopag and LGD4665, to changes in response to recombinant human thrombopoietin (TPO). Keywords: Drug Treatment