Biology subjects

Isensee, J.

Publications and source records attributed to Isensee, J..

7 recordsLinked to original sources

bioRxiv2026

Suzetrigine-evoked analgesia is potentiated by Nav1.7 null-related opioid mechanisms.

The genetic evidence for an essential role of sodium channel Nav1.7 in human pain conditions is compelling. Unfortunately, potent selective channel blockers of Nav1.7 are not useful analgesics because they have deleterious side effects, particularly on the autonomic nervous system. Here we have evaluated the downstream mechanisms induced by Nav1.7 loss in utero. Nav1.1 compensates for loss of Nav1.7 in sensory neurons and antisense Nav1.1 oligonucleotides diminish excitability in Nav1.7 embryonic null sensory neurons. Enhanced endogenous opioid signalling contributes substantially to analgesia. This is linked to altered gene expression that potentiates opioid signalling through lowered levels of proteins that terminate G-protein signalling (RGS4 and RGS8). There is also enhanced opioid drive through increased enkephalin levels linked to lowered sodium levels in Nav1.7 null neurons. Opioid signalling is the main driver of analgesia, but enhanced potassium channel expression (KCNC4 KCNK2, KCNMB2, KCNAB3) all implicated in pain control, may also contribute to the small level of naloxone-resistant analgesia. These findings suggest a potential new route to analgesia, through mimicking the events at Nav1.7 null sensory neuron terminals. Here we demonstrate potentiation of suzetrigine-evoked analgesia with RGS antagonists alone or in combination with normally inactive doses of morphine in formalin-evoked pain and CFA-induced inflammatory pain. Intriguingly, no analgesia is observed with acute pain. Cancer pain is under investigation. These data are of potential clinical interest.

neuroscience↗

bioRxiv2026

A mechanistic model of protein kinase A dynamics under pro- and anti-nociceptive inputs

Protein kinase A (PKA) is a central integrator of nociceptive signaling, yet a quantitative account of how pro- and anti-nociceptive inputs shape its dynamics remains incomplete. Here, we develop a mechanistic model of PKA activity in nociceptive neurons that explicitly links receptor activation to downstream kinase regulation. Using time-course and dose-response measurements, we infer unknown process parameters and quantify parameter and prediction uncertainties to ensure robust conclusions. The model captures the activation of PKA by serotonin and forskolin and its suppression by opioids. We show how the model can be used for the assessment of alternative circuit topologies, and demonstrate that receptor context and stimulation history reconfigure PKA responsiveness, providing testable predictions for opioid modulation under clinically relevant dosing. This framework offers a principled basis for integrating PKA with broader pain-signaling networks, supports rational exploration of combination therapies, and establishes a general strategy for disentangling neuromodulatory control of kinase activity. Author summaryPain perception is modulated by a complex network of signaling pathways activated by different receptors with opposing effects. A key player in this process is protein kinase A (PKA), whose regulation by both serotonin and opioid receptors is not yet fully understood. In this study, we developed a mathematical model to investigate how these opposing signals affect PKA activity in sensory neurons. After estimating the unknown model parameters from a comprehensive dataset, we were able to quantitatively analyze the dynamic behavior of the system and use it for comparison of alternative circuit topologies. Our model provides a valuable tool for integrating diverse molecular interactions involved in pain processing and could help guide future efforts to develop better treatments for chronic pain and reduce opioid tolerance.

systems biology↗

bioRxiv2026

Senescence-associated Cdkn1a (p21) is upregulated in rodent dorsal root ganglion neurons across lesion-based neuropathic pain models

Senescence of peripheral sensory neurons has recently been associated with increased nociceptive signalling and pain chronification. Whether this association is found across pain conditions and independent study settings remains to be investigated. In this study, we made use of publicly available whole-genome transcriptome data sets on rodent dorsal root ganglion (DRG) tissue to investigate pain-related peripheral sensory neuron senescence across pain models and independent study settings. We focused on Cdkn1a (p21) and Cdkn2a (p16) expression levels as two widely-used senescence markers, and to explore their potential role in peripheral sensory neuron senescence. We found that Cdkn1a but not Cdkn2a RNA is significantly increased across different axotomy- and lesion-based neuropathic pain models, but less consistent in other pain models including inflammatory pain. We observed a sex-dependent effect of Cdkn1a upregulation following nerve injury, with significantly increased Cdkn1a RNA levels in DRG cells from female but not male rats. Lastly, Cdkn1a RNA levels are increased among all DRG neuronal subtypes, seem to reach their maximum three to seven days following nerve injury, and afterwards go back to baseline. These data suggest that Cdkn1a upregulation in DRG neurons is a widespread response to nerve injury that is found across independent study settings. SummaryAnalysis of publicly available whole-genome transcriptome data sets shows that senescence-associated Cdkn1a but not Cdkn2a expression is upregulated in DRG neurons across neuropathic pain models.

neuroscience↗

bioRxiv2025

CaV1.2-dependent excitation-transcription coupling modulates nociception

Peripheral nociceptive sensory neurons integrate various noxious inputs, resulting in local depolarization that triggers the firing of action potentials and thus the sensation of pain. We recently reported that nociceptor depolarization itself initiates signaling by the calcium channel Cav1.2 causing acute hyperalgesia in vivo. However, whether this mechanism initiates excitation-transcription (E-T) coupling and thereby leads to long-lasting modulation of nociceptor activity remains poorly understood. Using high content imaging of dorsal root ganglion (DRG) neurons, we here found that depolarization of nociceptors induces phosphorylation of the transcription factor (TF) cAMP-response element binding protein (CREB), which was affected by inhibition of protein kinase A (PKA) and calcineurin, but not Ca2+/calmodulin-dependent protein kinases. Genetic deletion or pharmacological inhibition of Cav1.2 confirmed its role in calcium-dependent kinase signaling and CREB phosphorylation after depolarization. In line with this, pharmacological modulation of Cav1 channels affected the expression of a subset of depolarization-regulated immediate early genes known to orchestrate a broader transcriptional response. Indeed, RNA-Seq analysis of DRG neurons from mice with a tissue-specific deletion of Cav1.2 in nociceptive sensory neurons (SNS-Cacna1c-/- mice) revealed downregulation of multiple calcium and potassium channel subunits as well as proteins involved in synaptic vesicle release and cell adhesion. Furthermore, repetitive firing of action potentials and release of the neuropeptide CGRP was impaired in Cav1.2-deficient sensory neurons. SNS-Cacna1c-/- mice showed increased sensitivity to noxious heat and exacerbated inflammatory but not neuropathic pain. In conclusion, our data suggest a Cav1.2-dependent E-T coupling mechanism in nociceptors that counteracts nociception in vivo. HighlightsO_LIDepolarization induces Cav1.2- and PKA-dependent phosphorylation of the transcriptional regulator CREB in nociceptors C_LIO_LICav1.2 regulates the expression of depolarization-induced immediate early genes and induces reorganization of the signaling network in nociceptors C_LIO_LICav1.2-deficient nociceptors downregulate multiple ion channel subunits as well as proteins involved in synaptic vesicle release and cell adhesion C_LIO_LICav1.2-deficient nociceptors show impaired depolarization-induced PKA-II signaling, CREB phosphorylation, repetitive firing of action potentials, and release of the neuropeptide CGRP C_LIO_LINociceptor-specific Cav1.2-deficiency in mice increases the sensitivity to noxious heat and exacerbates inflammatory pain C_LI In briefIsensee et al. report that depolarization of nociceptors induces calcium influx through Cav1.2 channels, thereby initiating a signaling cascade that links neuronal excitation to transcriptional regulation of immediate early genes (E-T coupling). Nociceptor-specific knockout of Cav1.2 led to transcriptional changes in nociceptor-specific genes and was associated with impaired depolarization-induced signaling, action potential firing, and neuropeptide release. As the Cav1.2-deficient mice show increased noxious heat sensitivity and exacerbated inflammatory pain, these findings suggest that Cav1.2-dependent E-T coupling mechanism counteracts nociception in vivo.

neuroscience↗

bioRxiv2025

3D dynamic multiscale force and shape analysis of in-vivo elastic stress sensors

The measurement of stresses and forces at the tissue level has proven to be an indispensable tool for the understanding of complex biological phenomena such as cancer invasion, embryo development or wound healing. One of the most versatile tools for force inference at the cell and tissue level are elastic force sensors, whose biocompatibility and tunable material properties make them suitable for many different experimental scenarios. The evaluation of those forces, however, is still a bottleneck due to the numerical methods seen in literature until now, which are usually slow and render low experimental yield. Here we present Bead-Buddy, a ready-to-use platform for the evaluation of deformation and stresses from fluorescently labelled sensors within seconds. The strengths of BeadBuddy lie in the pre-computed analytical solutions of the elastic problem, the abstraction of data into Spherical Harmonics, and a simple user interface that creates a smooth workflow for force inference. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=174 SRC="FIGDIR/small/633835v3_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@80c95corg.highwire.dtl.DTLVardef@123d712org.highwire.dtl.DTLVardef@1fd1ce0org.highwire.dtl.DTLVardef@72c688_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2022

Autophagy regulates neuronal excitability by controlling cAMP/Protein Kinase A signaling

Autophagy provides nutrients during starvation and eliminates detrimental cellular components. However, accumulating evidence indicates that autophagy is not merely a housekeeping process. Here, we show that the protein AuTophaGy 5 (ATG5) functions in neurons to regulate the cAMP-dependent protein kinase A (PKA)-mediated phosphorylation of a synapse-confined proteome. This function of ATG5 is independent of bulk turnover of synaptic proteins and requires the targeting of PKA inhibitory R1 subunits to autophagosomes. Neuronal loss of ATG5 causes synaptic accumulation of PKA R1, which sequesters the PKA catalytic subunit and diminishes the cAMP/PKA-dependent phosphorylation of postsynaptic cytoskeletal proteins mediating AMPAR trafficking. Glutamatergic neurons-confined ATG5 deletion augments AMPAR-dependent excitatory neurotransmission and causes the appearance of spontaneous recurrent seizures in mice. Our findings identify a novel role of autophagy in regulating PKA signaling at glutamatergic synapses and suggest the PKA as a target for restoration of synaptic function in neurodegenerative conditions with autophagy dysfunction.

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↗