Biology subjects

Miller, L. N.

Publications and source records attributed to Miller, L. N..

4 recordsLinked to original sources

bioRxiv2025

NGN2 Expression and Regional Patterning Allow Rapid Differentiation from hiPSCs to DRG-Like Neurons Responsive to Type 2 Cytokines

Itch or pruritus, is a sensation that elicits scratching behaviour and is a major symptom and cause of morbidity in skin diseases such as atopic dermatitis (AD), allergic contact dermatitis (ACD), prurigo nodularis (PN), and urticaria. Itch is often triggered by inflammatory stimuli in the skin including type 2 cytokines such as IL-4, IL-13, and/or IL-31. Several therapies targeting type 2 immune pathways have been developed to treat pruritus; however, itch improvement in many patients remains to be improved. Thus, additional approaches to modulate sensory neuron activity are needed. Ex vivo or even in vitro study of the molecular mechanisms underlying primary sensory neuron activation is challenging since harvesting neurons from dorsal root ganglia (DRG) in patients can only be done from cadavers. Herein, we describe rapid human sensory neurons generation (2 days to precursor cells) by in vitro differentiation of human induced pluripotent stem cells (hiPSC) from simultaneous application of patterning factors with NGN2 overexpression. We show that these hiPSC-derived sensory neurons possess key characteristics of primary sensory neurons. They express key neuronal markers, such as TRKA receptors, TRPV1 and TRPA1 channels, and functionally respond to the TRPV1 agonist capsaicin. In addition, they express key type 2 cytokine receptors such as interleukin (IL)-4R and IL31-R, known to promote itch in AD and PN. Moreover, these cells are functional as our sensory neurons respond to IL-4, IL-13 and IL-31 stimulation. Collectively, these data demonstrate that our protocol generates a phenotypic profile consistent with native somatosensory neurons that can facilitate development of novel approaches to model and treat pruritic disease.

neuroscience↗

bioRxiv2023

Neural stem and progenitor cells support and protect adult hippocampal function via vascular endothelial growth factor secretion.

Adult neural stem and progenitor cells (NSPCs) reside in the dentate gyrus (DG) of the hippocampus throughout the lifespan of most mammalian species. In addition to generating new neurons, NSPCs may alter their niche via secretion of growth factors and cytokines. We recently showed that adult DG NSPCs secrete vascular endothelial growth factor (VEGF), which is critical for maintaining adult neurogenesis. Here, we asked whether NSPC-derived VEGF alters hippocampal function independent of adult neurogenesis. We found that loss of NSPC-derived VEGF acutely impaired hippocampal memory, caused neuronal hyperexcitability and exacerbated excitotoxic injury. We also found that NSPCs generate substantial proportions of total DG VEGF and VEGF disperses broadly throughout the DG, both of which help explain how this anatomically-restricted cell population could modulate function broadly. These findings suggest that NSPCs actively support and protect DG function via secreted VEGF, thereby providing a non-neurogenic functional dimension to endogenous NSPCs.

neuroscience↗

bioRxiv2020

Identification and characterization of diverse OTU deubiquitinases in bacteria

Manipulation of host ubiquitin signaling is becoming an increasingly apparent evolutionary strategy among bacterial and viral pathogens. By removing host ubiquitin signals, for example, invading pathogens can inactivate immune response pathways and evade detection. The Ovarian Tumor (OTU) family of deubiquitinases regulates diverse ubiquitin signals in humans. Viral pathogens have also extensively co-opted the OTU fold to subvert host signaling, but the extent to which bacteria utilize the OTU fold was unknown. We have predicted and validated a set of OTU deubiquitinases encoded by several classes of pathogenic bacteria. Biochemical assays highlight the ubiquitin and polyubiquitin linkage specificities of these bacterial deubiquitinases. By determining the ubiquitin-bound structures of two examples, we demonstrate the novel strategies that have evolved to both thread an OTU fold and to recognize a ubiquitin substrate. With these new examples, we perform the first cross-kingdom structural analysis of the OTU fold that highlights commonalities among distantly-related OTU deubiquitinases.

biochemistry↗

bioRxiv2019

Second Harmonic Generation Spectroscopy of Membrane Probe Dynamics in Gram-Positive Bacteria

Bacterial membranes are complex mixtures with dispersity that is dynamic over scales of both space and time. In order to capture adsorption onto and transport within these mixtures, we conduct simultaneous second harmonic generation (SHG) and two photon fluorescence measurements on two different gram-positive bacterial species as the cells uptake membrane-specific probe molecules. Our results show that SHG can not only monitor the movement of small molecules across membrane leaflets, but is also sensitive to higher-level ordering of the molecules within the membrane. Further, we show that the membranes of Staphylococcus aureus remain more dynamic after longer times at room temperature in comparison to Enterococcus faecalis. Our findings provide insight into the variability of activities seen between structurally similar molecules in gram-positive bacteria while also demonstrating the power of SHG to examine these dynamics.\n\nSTATEMENT OF SIGNIFICANCEBacterial membranes are highly adept at discerning and modifying their interactions with different small molecules in their environment. Here we show how second harmonic generation (SHG) spectroscopy can track the dynamics of structurally similar membrane probes in two gram-positive bacterial species. Our results reveal behavior that is dependent on both the probe molecule and the membrane composition. Specifically, we observe flip-flop between leaflets for one molecule, while the other molecule produces a signal indicative of larger scale ordering in the membrane. These phenomena can all be explained by considering potential differences in the membrane fluidity and surface charge between the two bacterial species. Overall, our work highlights the dynamic differences between bacterial membranes and SHGs sensitivity to probing these systems.

biophysics↗