1. Cellular state determines the multimodal signaling response of single cells
Bernhard A. Kramer, Lucas Pelkmans
https://doi.org/10.1101/2019.12.18.880930
Numerous fundamental biological processes require individual cells to correctly interpret and accurately respond to incoming cues. How intracellular signaling networks achieve the integration of complex information from various contexts remains unclear. Here we quantify epidermal growth factor-induced heterogeneous activation of multiple signaling proteins, as well as cellular state markers, in the same single cells across multiple spatial scales. We find that the acute response of each node in a signaling network is tightly coupled to the cellular state in a partially non-redundant manner. This generates a multimodal response that senses the diversity of cellular states better than any individual response alone and allows individual cells to accurately place growth factor concentration in the context of their cellular state. We propose that the non-redundant multimodal property of signaling networks in mammalian cells underlies specific and context-aware cellular decision making in a multicellular setting.
2. Inhibition of tumor growth by a novel engineered chimeric toxin that cleaves activated mutant and wild-type RAS
Vania Vidimar, Greg L. Beilhartz, Minyoung Park, Marco Biancucci, Matthew B. Kieffer, David R. Gius, Roman A. Melnyk, Karla J Satchell
doi: https://doi.org/10.1101/2019.12.17.880187
Despite nearly four decades of effort, broad inhibition of oncogenic RAS using small molecule approaches has proven to be a major challenge. Here we describe the development of a novel pan-RAS biologic inhibitor comprised of the RAS-RAP1-specific endopeptidase fused to the protein delivery machinery of diphtheria toxin. We show that this engineered chimeric toxin irreversibly cleaves and inactivates intracellular RAS at low picomolar concentrations terminating downstream signaling in receptor-bearing cells. Further, we demonstrate in vivo target engagement and reduction of tumor burden in three mouse xenograft models driven by either wild-type or mutant RAS. Intracellular delivery of a potent anti-RAS biologic through a receptor-mediated mechanism represents a promising new approach to developing RAS therapeutics against a broad array of cancers.
3. Contrast-Enhanced, Molecular Imaging of Vascular Inflammation in the Mouse Model by Simultaneous PET/MRI
Siyi Du, Thomas S.C. Ng, Adrian House, Tang Tang, Lin Zheng, Chuqiao Tu, Janice Peake, Imelda E. Espiritu, Kwan-Liu Ma, Kent Pinkerton, Russell E. Jacobs, Angelique Y. Louie
doi: https://doi.org/10.1101/2019.12.16.878652
Despite advances in diagnosis and management, cardiovascular diseases (CVDs) remain the leading cause of death in the US. Atherosclerosis is the most common form of CVD and the vulnerability of atherosclerotic plaques to rupture is a primary determinant for risk of catastrophic ischemic events. Current imaging of atherosclerotic disease focuses on assessing plaque size and the degree of luminal stenosis, which are not good predictors of plaque stability. Functional methods to identify biomarkers of inflammation in plaques could facilitate assessment of plaque instability to allow early intervention. In this study, we validate the use of a purpose-built, magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) insert for multimodal, molecular imaging of vulnerable plaques in mice. We illustrate the application of PET to screen for inflamed regions to guide the application of MRI. Molecular MRI visualizes regions of vascular inflammation and is coupled with anatomical MRI to generate detailed maps of the inflammatory marker within the context of an individual vessel. As a testbed for this imaging methodology, we developed a multimodal, iron oxide nanoparticle (NP) targeting vascular cell adhesion molecule-1 (VCAM-1) for simultaneous PET/MRI of vascular inflammation performed on a mouse carotid ligation model. In vitro cell studies confirmed that the NPs are not cytotoxic to liver cells. In vivo simultaneous PET/MRI imaging identified regions of inflammation. Three-dimensional rendering of the MRI data facilitated high-resolution visualization of patterns of inflammation along the injured vessel. Histology validated the co-localization of the NPs with VCAM-1 expression at sites of induced inflammation. The results of this work validate the utility of the simultaneous PET/MR insert as a research tool for small animals and lays groundwork to further advance the potential clinical utility of integrated imaging systems.
