Biology subjects

Steinbach, A. M.

Publications and source records attributed to Steinbach, A. M..

3 recordsLinked to original sources

bioRxiv2026

Bayesian Stacking of Quantitative Adverse Outcome Pathways Isolates Primary Drivers of Liver Steatosis

The quantification of adverse outcome pathways (qAOPs) involving multiple converging pathways remains a fundamental challenge in toxicology. This difficulty is worsened by small in vitro datasets with missing values and heteroscedasticity, which limit the estimation of non-linear response functions and the robust estimation of uncertainty. To overcome these limitations, we developed a framework for estimating a Bayesian qAOP Ensemble (Bayesian qAOPE) that combines heteroscedastic dose-response functions with continuous splines and linear models. By combining multiple converging non-linear pathways through Bayesian stacking, the most meaningful pathways are identified, and strongly correlated responses are naturally accounted for. Applying our approach to a hepatic steatosis dataset, we demonstrate by exact Bayesian leave-one-out cross-validation that our framework yields an exceptional predictive performance suitable for the derivation of a probabilistically weighted Benchmark Dose (BMD). Our framework is highly adaptable and provides a chemical-agnostic, mathematically founded blueprint for integrating multiple converging pathways in a Bayesian network.

pharmacology and toxicology↗

bioRxiv2023

Cross-family small GTPase ubiquitination by the intracellular pathogen Legionella pneumophila

The intracellular bacterial pathogen Legionella pneumophila (L.p.) manipulates eukaryotic host ubiquitination machinery to form its replicative vacuole. While nearly 10% of L.p.s arsenal of [~]330 secreted effector proteins have been biochemically characterized as ubiquitin ligases or deubiquitinases, a comprehensive measure of temporally resolved changes in the endogenous host ubiquitinome during infection has not been undertaken. To elucidate how L.p hijacks ubiquitin signaling within the host cell, we undertook a proteome-wide analysis of changes in protein ubiquitination during infection. We discover that L.p. infection results in increased ubiquitination of host proteins regulating subcellular trafficking and membrane dynamics, most notably 63 of [~]160 mammalian Ras superfamily small GTPases. We determine that these small GTPases predominantly undergo non-degradative monoubiquitination, and link ubiquitination to recruitment to the Legionella-containing vacuole membrane. Finally, we find that the bacterial effectors SidC/SdcA play a central, but likely indirect, role in cross-family small GTPase ubiquitination. This work highlights the extensive reconfiguration of host ubiquitin signaling by bacterial effectors during infection and establishes simultaneous ubiquitination of small GTPases across the Ras superfamily as a novel consequence of L.p. infection. This work positions L.p. as a tool to better understand how small GTPases can be regulated by ubiquitination in uninfected contexts.

microbiology↗

bioRxiv2018

Chimeric antigen receptors that trigger phagocytosis

Chimeric antigen receptors (CARs) are synthetic receptors that reprogram T cells to kill cancer. The success of CAR-T cell therapies highlights the promise of programmed immunity, and suggests that applying CAR strategies to other immune cell lineages may be beneficial. Here, we engineered a family of Chimeric Antigen Receptors for Phagocytosis (CAR-Ps) that direct macrophages to engulf specific targets, including cancer cells. CAR-Ps consist of an extracellular antibody fragment, which can be modified to direct CAR-P activity towards specific antigens. By screening a panel of engulfment receptor intracellular domains, we found that the cytosolic domains from Megf10 and FcR{gamma} robustly triggered engulfment independently of their native extracellular domain. We show that CAR-Ps drive specific engulfment of antigen-coated synthetic particles and whole cancer cells. Addition of a tandem PI3K recruitment domain increased cancer cell engulfment. Finally, we show that CAR-P expressing macrophages reduce cancer cell number in co-culture by over 40%.\n\nSummaryWe report the first Chimeric Antigen Receptors for Phagocytosis (CAR-Ps) that promote engulfment of antigen-coated particles and cancer cells.

cell biology↗