Biology subjects

Bean, B. P.

Publications and source records attributed to Bean, B. P..

7 recordsLinked to original sources

bioRxiv2026

Modulation of human dorsal root ganglion neuron excitability by Nav1.7 inhibition

Nav1.7 voltage-gated sodium channels are strongly expressed in human primary pain-sensing neurons (nociceptors) and selective Nav1.7 inhibitors have been developed as possible therapeutic agents for treating pain, so far with disappointing clinical results. In contrast, a selective Nav1.8 channel inhibitor (suzetrigine) has had successful clinical trials. Because nociceptors express both Nav1.7 and Nav1.8 channels, it is of interest to compare effects of Nav1.7 and Nav1.8 inhibitors on the excitability of human nociceptors. To compare with previous results with suzetrigine, we characterized the effects of a selective Nav.7 inhibitor, AM-2099, on action potential generation and repetitive firing of dissociated human dorsal root ganglion neurons, studied at 37{degrees}C. Inhibition of Nav1.7 channels by 600 nM AM-2099 generally produced a substantial depolarizing shift of action potential threshold, an increase in rheobase, a decrease in action potential upstroke velocity, decrease in action potential peak, and prolongation of refractory period. Compared to inhibition of Nav1.8 channels, inhibition of Nav1.7 channels had larger effects on threshold and maximal upstroke velocity, while action potential peak was reduced similarly by both. Nav1.8 inhibition produced much more dramatic reduction of repetitive firing than Nav1.7 inhibition. The results show that although the excitability of human DRG neurons is affected by inhibition of Nav1.7 channels, most notably by an increase in threshold and increase in refractory period, repetitive firing of the neurons in response to strong stimuli is little affected.

neuroscience↗

bioRxiv2023

Downregulation of the silent potassium channel Kv8.1 increases ALS motor neuron vulnerability

The Kv8.1 potassium ion channel encoded by the KCNV1 gene is a "silent" subunit whose biological function is unknown. In ALS patient-derived motor neurons carrying SOD1(A4V) and C9orf72 mutations, its expression is highly reduced, yielding increased vulnerability to cell death without a change in motor neuronal firing. Our data suggests that Kv8.1 modulates Kv2 channel function to impact neuronal metabolism and lipid/protein transport pathways, but not excitability.

neuroscience↗

bioRxiv2022

Scalable Generation of Pseudo-Unipolar Sensory Neurons from Human Pluripotent Stem Cells

Development of new non-addictive analgesics requires advanced strategies to differentiate human pluripotent stem cells (hPSCs) into relevant cell types amenable for translational research. Here, we developed a highly efficient and reproducible method that differentiates hPSCs into peptidergic and non-peptidergic nociceptors. By modulating specific cell signaling pathways, hPSCs were first converted into SOX10+ neural crest cells, followed by differentiation into sensory neurons with an in vivo-like pseudo-unipolar morphology. Detailed characterization confirmed that the hPSC-derived nociceptors displayed molecular and cellular features comparable to native dorsal root ganglion (DRG) neurons, and expressed high-threshold primary sensory neuron markers, transcription factors, neuropeptides, and over 150 ion channels and receptors, including critical pain-relevant drug targets (e.g., TRPV1, TAC1, CALCA, NAV1.7, NAV1.8). Moreover, after confirming robust functional activities and differential response to noxious stimuli and specific drugs, a robotic cell culture system was employed to produce large quantities of human sensory neurons, which can be used to develop nociceptor-selective analgesics.

developmental biology↗

bioRxiv2021

Cannabidiol activates neuronal Kv7 channels

Cannabidiol (CBD), a chemical found in the Cannabis sativa plant, is a clinically effective antiepileptic drug whose mechanism of action is unknown. Using a fluorescence-based thallium flux assay, we performed a large-scale screen and found enhancement of flux through heterologously-expressed human Kv7.2/7.3 channels by CBD. Using patch clamp recordings, we found that CBD at low concentrations activates Kv7.2/7.3 channels at subthreshold voltages, with 100 nM CBD producing a doubling of current at -50 mV. CBD shifted the voltage-dependence of channels in the hyperpolarizing direction, producing a shift in the midpoint of activation by [~]-14 mV at 300 nM. CBD also effectively enhanced native M-current in both mouse superior cervical ganglion neurons and rat hippocampal neurons. The potent enhancement of Kv2/7.3 channels by CBD seems likely to contribute to its effectiveness as an antiepileptic drug by reducing neuronal hyperexcitability.

neuroscience↗

bioRxiv2021

Bi-directional flow of the funny current (If) during the pacemaking cycle in murine sinoatrial node myocytes

Sinoatrial node myocytes (SAMs) act as cardiac pacemaker cells by firing spontaneous action potentials (APs) that initiate each heartbeat. The funny current, If, is critical for the generation of these spontaneous APs; however, its precise role during the pacemaking cycle remains unresolved. We used the AP-clamp technique to quantify If during the cardiac cycle in mouse SAMs. We found that If is persistently active throughout the sinoatrial AP, with surprisingly little voltage-dependent gating. As a consequence, it carries both inward and outward current around its reversal potential of -30 mV. Despite operating at only 2-5% of its maximal conductance, If carries a substantial fraction of both depolarizing and repolarizing net charge movement during the firing cycle. We also show that {beta}-adrenergic receptor stimulation increases the percentage of net depolarizing charge moved by If, consistent with a contribution of If to the fight-or-flight increase in heart rate. These properties were confirmed by heterologously-expressed HCN4 channels and by mathematical models of If. Modelling further suggested that the slow activation and deactivation of the HCN4 isoform underlie the persistent activity of If during the sinoatrial AP. These results establish a new conceptual framework for the role of If in pacemaking, in which it operates at a very small fraction of maximal activation but nevertheless drives membrane potential oscillations in SAMs by providing substantial driving force in both inward and outward directions. Significance StatementCardiac pacemaker cells trigger each heartbeat by virtue of spontaneous oscillations in their membrane voltage. Although the funny current (If) is critical for these oscillations and for setting heart rate, its precise role remains an enigma because it activates mostly outside of the physiological voltage range and quite slowly relative to the pacemaker cycle. Here we show that If is persistently active in pacemaker cells; once opened, the small fraction of ion channels that conduct If do not re-close. Consequently, If flows both inward and outward to help propel the voltage oscillations and it paradoxically conducts a large fraction of the net charge movement. These results establish a new conceptual framework for the role of If in driving cardiac pacemaking.

physiology↗

bioRxiv2020

Inhibiting cough by silencing large pore-expressing airway sensory neurons with a charged sodium channel blocker

Although multiple diseases of the respiratory system cause cough, there are few effective treatments for this common condition. We previously developed a strategy to treat pain and itch via the long-lasting inhibition of nociceptor sensory neurons with QX-314, a cationic sodium channel blocker that selectively enters only into activated nociceptors by permeating through the endogenous TRPV1 and TRPA1 large pore ion channels they express. In this study we design and characterize BW-031, a novel cationic compound with [~]6-fold greater potency than QX-314 for inhibiting sodium channels when introduced inside cells and with minimal extracellular activity. We show that inhalation of aerosolized BW-031 effectively inhibits citric acid-induced cough in an allergic inflammation guinea pig cough model. These data support the use of charged sodium channel blockers for the selective inhibition of airway sensory neurons with activated large pore channels as a novel targeted therapy for treating cough.

neuroscience↗

bioRxiv2020

Anthrax Toxin as a Molecular Platform to Target Nociceptive Neurons and Modulate Pain

Bacterial toxins are able to act on neurons to modulate signaling and function. Here, we find that nociceptive sensory neurons that mediate pain are enriched in the receptor for anthrax toxins, ANTXR2. Anthrax Edema Toxin (ET) induced cAMP and PKA signaling in Nav1.8+ nociceptive neurons and modulated pain in vivo. Peripherally administered ET mediated mechanical allodynia in naive mice and during B. anthracis infection. Intrathecally administered ET produced analgesic effects, potently blocking pain-like behaviors in multiple mouse models of inflammatory and chronic neuropathic pain. Nociceptor-specific ablation of ANTXR2 attenuated ET-induced signaling and analgesia. Modified anthrax toxin successfully delivered exogenous protein cargo into nociceptive neurons, illustrating utility of the anthrax toxin system as a molecular platform to target pain. ET further induced signaling in human iPSC-derived sensory neurons. Our findings highlight novel interactions between a bacterial toxin and nociceptors that may be utilized for developing new pain therapeutics. SUMMARYANTXR2 expression on nociceptive neurons allows selective targeting and modulation of pain by native and engineered anthrax toxins.

neuroscience↗