Biology subjects

McKenna, S.

Publications and source records attributed to McKenna, S..

5 recordsLinked to original sources

bioRxiv2026

Sphingosine 1-phosphate lyase expressed in pulmonary epithelial cells potentiates host innate defenses and alleviates influenza pathogenicity in mice

Influenza viruses circulate in humans, causing a substantial burden on global health. Investigation of influenza-host interactions could identify host factors that regulate influenza pathogenicity. Sphingosine 1-phosphate (S1P) is a bioactive lipid mediator and regulates crucial cellular processes. S1P lyase (SPL), an enzyme that mediates S1P degradation, was shown to display anti-influenza activity in a cell culture system. Here, we constructed a mouse model to demonstrate the antiviral function of SPL in respiratory epithelial cells during influenza in vivo. Deletion of SPL from lung epithelial cells exacerbated influenza-induced weight loss and mortality. Influenza virus began to propagate more effectively in the absence of SPL at the innate immune stage. Increased virus titers were sustained during influenza and associated with enhanced accumulation of multiple immune cell types in the lungs. Single-cell RNA sequencing was conducted to further define the function of SPL in lung epithelial cells. SPL deletion increased the proportion of alveolar type 1 (AT1) cells compared to alveolar type 2 (AT2) cells with alteration of the related signaling pathways, suggesting a role of SPL in AT1/AT2 programming. Importantly, host innate defense pathways were changed in SPL-deficient lung epithelial cells upon infection, which corroborates the antiviral function of SPL. This study elucidates the host protective function of SPL in lung epithelial cells during influenza and provides gene signature profiles critical for SPL-mediated alleviation of influenza pathogenicity. The findings may contribute to development of host-directed therapeutics to better control influenza.

microbiology↗

bioRxiv2026

Spatially defined axonal guidance in neural organoids with micropatterned microfluidic channels

Three-dimensional stem cell-derived neural organoids provide a promising platform for investigating early brain development and interregional circuit formation. Although co-culture of region-specific organoids into assembloids has enabled the study of cortical and subcortical interactions, these models lack directional specificity and spatial control, limiting their ability to recapitulate canonical circuit architecture. Here, we present a microfluidic platform for constructing directional and tunable interregional circuits while preserving anatomical distinction. This system, which we term "directoids" incorporates micropatterned polydimethylsiloxane (PDMS) microstructures to control uni- and bidirectional axonal growth between cortical and thalamic organoids. We observed a 70.4% success rate of axons traversing the full channel length in the permissive direction and reaching the opposing organoid, whereas no neurites successfully crossed the probative direction. These results demonstrate robust directionally bias in axon outgrowth and establish a scalable, reproducible strategy for controlling asymmetric connectivity between anatomically distinct neural organoids. Using high-density CMOS microelectrode arrays, we further validated directional tuning of extracellular action potential propagation within directoid microchannels, a feature not observed in straight-channel connectoid controls. Directoids also exhibited significant asymmetry in firing rates between channel entry and exit sites, consistent with engineered bias in signal flow. This provides an experimental paradigm for dissecting how anatomical connectivity and functional activity converge to shape neuronal networks. Together, these findings establish a microfluidic platform for investigating the mechanisms underlying hierarchical circuit formation, regional specification, and functional integration in developing human neural organoid models at cellular resolution not possible in vivo.

bioengineering↗

bioRxiv2025

YAP/TEAD4-reagulated placental alkaline phosphatases ALPP and ALPPL2 are immunosuppressive ectonucleotidases modulated by MAPK inhibitors

Placental alkaline phosphatases ALPP and ALPPL2 (ALPP/L2) are promising clinical targets for therapies such as antibody-drug conjugates (ADCs). However, their regulation and biological functions remain unclear. Here, we identify the YAP/TEAD4 signaling axis as the primary regulator of ALPP/L2 expression in tumor cells. Importantly, we demonstrate that inhibitors targeting KRAS, MEK, and ERK upregulate ALPP/L2 expression in vitro and in vivo, thereby enhancing the efficacy of antibody-drug conjugates (ADCs) when used in combination. Moreover, our work reveals a novel immunomodulatory function of ALPP/L2 as cell surface ectonucleotidases that hydrolyze extracellular ATP, ADP, and AMP to adenosine, promoting regulatory T cell infiltration into the tumor microenvironment. Together, these findings reveal a biological function of ALPP/L2 and identify druggable regulators to enhance ALPP/L2-targeted therapies. SIGNIFICANCEThis study uncovers the YAP/TEAD pathway as a positive regulator of the clinically relevant tumor-associated antigens ALPP and ALPPL2. Kras, MEK, or ERK inhibitors enhance ALPP/L2 expression in tumor cells, thereby increasing the efficacy of ALPP/L2-targeted antibody-drug conjugates. These findings offer a promising combination strategy to overcome resistance to ALPP/L2-based therapies caused by low target expression.

cancer biology↗

bioRxiv2025

Sphingosine kinase 2 suppresses neutrophil responses to promote viral persistence while attenuating immune pathology

Chronic virus infections often suppress immune cell functions which helps in restricting immune pathology but leads to viral persistence. However, the underlying mechanisms are incompletely understood. We recently found that sphingosine kinase 2 (SphK2)-deficient (Sphk2-/-) mice succumbed to lymphocytic choriomeningitis virus (LCMV) infection due to immune pathology. In addition to heightened T cell immunity, a notable increase of neutrophils was observed in LCMV-infected Sphk2-/- mice. Depletion of neutrophils increased the viability of virus-infected Sphk2-/- mice, supporting a role of SphK2-deficient neutrophils in viral immune pathogenesis. Further, SphK2-deficient neutrophils expressed lower levels of the immune suppressive marker CD244 during infection. Importantly, adoptively transferred SphK2-deficient neutrophils demonstrated intrinsic regulation of CD244 and improved virus-specific T cell responses, resulting in diminished viral burden. Transcriptomic analysis revealed increased expression of pro-inflammatory and antiviral genes in SphK2-deficient neutrophils. These results indicate that SphK2 promotes suppressive neutrophil responses and regulates neutrophil-associated immune pathology during a persistent infection. Our findings may help design new immune therapeutics to control chronic viral diseases. SignificanceNeutrophils are the sentinels of the innate immune system; they can reshape innate and adaptive immune responses. During chronic illnesses, such as persistent viral infections, neutrophils can suppress the host immune response and help in disease progression. Here, we demonstrate regulation of neutrophil expansion and functions by sphingosine kinase 2 (SphK2) during LCMV infection. SphK2-deficient neutrophils express a reduced level of inhibitory receptor CD244, exert immune stimulatory effects on T cells, and promote virus clearance. Further, transcriptomic analysis reveals that SphK2 deficiency leads to the development of proinflammatory neutrophils. Our study identifies SphK2, a host factor, as being critical for neutrophil suppression that regulates dysfunctional T cell response and virus persistence.

immunology↗

bioRxiv2019

BAX and SMAC Regulate Bistable Properties of the Apoptotic Caspase System

The initiation of apoptosis is a core mechanism in cellular biology by which organisms control the removal of damaged or unnecessary cells. The irreversible activation of caspases is essential for apoptosis, and mathematical models have demonstrated that the process is tightly regulated by positive feedback and a bistable switch. BAX and SMAC are often dysregulated in diseases such as cancer or neurodegeneration and are two key regulators that interact with the caspase system generating the apoptotic switch. Here we present a mathematical model of how BAX and SMAC control the apoptotic switch. Formulated as a system of ordinary differential equations, the model summarises experimental and computational evidence form the literature and incorporates the biochemical mechanisms of how BAX and SMAC interact with the components of the caspase system. Using simulations and bifurcation analysis, we find that both BAX and SMAC regulate the time-delay and activation threshold of the apoptotic switch. Interestingly, the model predicted that BAX (not SMAC) controls the amplitude of the apoptotic switch. Cell culture experiments using siRNA mediated BAX and SMAC knockdowns this model prediction. We further validated the model on data of the NCI-60 cell line panel using BAX protein expression as cell-line specific parameter and show that model simulations correlated with the cellular response to DNA damaging drugs and established a defined threshold for caspase activation that could distinguish between sensitive and resistant melanoma cells. In summary, we present an experimentally validated dynamic model that summarises our current knowledge of how BAX and SMAC regulate the bistable properties of irreversible caspase activation during apoptosis.

systems biology↗