Biology subjects

Sarret, P.

Publications and source records attributed to Sarret, P..

8 recordsLinked to original sources

bioRxiv2025

A neurotensin receptor type 1-derived pepducin acts as a biased allosteric modulator to regulate target receptor function

Pepducins are synthetic membrane-tethered lipopeptides designed to allosterically modulate G protein-coupled receptor (GPCR) signaling. Here, we characterize a series of pepducins targeting the neurotensin receptor type 1 (NTS1), revealing multifaceted modulation of this receptor class. Using BRET-based biosensors, we show that PP-001, a pepducin derived from NTS1s first intracellular loop, preferentially activates G protein over {beta}-arrestin signaling while inhibiting NT binding, NT-induced {beta}-arrestin recruitment, and NTS1 receptor internalization, thereby acting as biased allosteric agonist and negative allosteric modulator. PP-001 also promotes the formation of both homo- and heteromeric multi-receptor units. In vivo, PP-001 elicits potent, sustained hypotensive effects, reversible by the NTS1 antagonist SR48692. Finally, although the mechanism of pepducin-receptor interaction remains unclear, this study identifies a critical N-terminal RKK motif for PP-001s biological activity. Thermodenaturation assays with purified NTS1 and mutagenesis further provide evidence for the role of NTS1s H8 domain in direct pepducin-receptor interaction. This work highlights pepducins modulatory potential as pharmacological tools for GPCR-targeted drug development.

pharmacology and toxicology↗

bioRxiv2024

CCR2 silencing in sensory neurons blocks bone cancer progression

The peripheral nervous system contributes to cancer growth, in part by shaping the immunological niche of the tumor. How the nervous system influences bone cancer progression, and whether the underlying neuroimmune pathways can be targeted therapeutically, remain unclear. Here we demonstrate a profound influence of the peripheral nervous system on tumor progression that can be countered by silencing chemokine receptor signaling in sensory neurons. Axotomy of the tumor-innervating femoral nerve inhibits tumor progression in animals bearing bone cancer, whereas intrathecal delivery of the tumor-associated proinflammatory chemokine CCL2 promotes both tumor growth and allodynia. Silencing CCR2 in dorsal root ganglion (DRG) neurons with a newly developed lipid nanoparticle-formulated Dicer-substrate siRNA impedes tumor progression and pathological bone remodeling, and relieves bone cancer-associated pain. Mechanistically, bone cancer drives CCR2-dependent transport of substance P and CGRP along the tumor-innervating femoral nerve, and these neuropeptides expand the tumor-associated macrophage population; silencing CCR2 in DRG neurons normalizes the neuropeptide milieu and ameliorates altered bone remodeling. We thus define a targetable neuroimmune axis that contributes to cancer progression. HighlightsO_LICancer progression activates sensory neurons, driving pain hypersensitivity and neuropeptide release. C_LIO_LIAxotomy of the tumor-innervating femoral nerve impedes tumor progression. C_LIO_LICCL2-CCR2 signaling in DRG neurons promotes pain hypersensitivity and cancer growth. C_LIO_LISilencing CCR2 in the DRG reduces pain hypersensitivity, tumor-associated macrophage numbers and cancer growth. C_LI

neuroscience↗

bioRxiv2023

CCR2-targeting pepducins reduce T cell-nociceptor interaction driving bone cancer pain

Inhibition of the CCL2/CCR2 chemokine signaling represents a promising avenue for the development of non-opioid pain treatment, particularly for painful bone metastases. To investigate the involvement of CCR2 in cancer-induced bone pain, we generated and characterized the functional activities of a novel cell-penetrating pepducin, namely PP101, acting as an intracellular negative allosteric modulator of CCR2. In vivo, PP101 was effective in relieving neuropathic and bone cancer pain. By targeting CCR2, PP101 reduced bone cancer pain by preventing infiltration of CD4+ and CD8+ T cells and by decreasing the neuroimmune communication network within the dorsal root ganglia. Importantly, reduced neuroinflammatory milieu in the dorsal root ganglia induced by PP101 did not result in deleterious tumor progression or behavioral adverse effects. Thus, targeting the neuroimmune crosstalk through allosteric inhibition of CCR2 may represent an effective and safe avenue for the management of bone cancer pain. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/556569v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@15c2d43org.highwire.dtl.DTLVardef@9fa40corg.highwire.dtl.DTLVardef@cb457dorg.highwire.dtl.DTLVardef@13f36e1_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIBreast cancer bone metastases induce pain by activating CCR2 on sensory neurons. C_LIO_LIDRG-infiltrating CD4+ and CD8+ T cells promote the development of bone cancer pain. C_LIO_LICCR2 inhibition by PP101 suppresses DRG neuroinflammation and neuronal excitability. C_LIO_LIPP101 alleviates bone cancer pain without behavioral or physiological side effects. C_LI

neuroscience↗

bioRxiv2022

Apelin Stimulation of the Perivascular MuSC Niche Enhances Endogenous Repair in Muscular Dystrophy

Impaired skeletal muscle stem cell (MuSC) function has long been suspected to contribute to the pathogenesis of muscular dystrophy (MD). Here we describe that defects in the endothelial cell (EC) compartment of the perivascular stem cell niche in three different types of MD are associated with inefficient mobilization of MuSCs following tissue damage. Using chemoinformatic analysis, we identified the 13 amino acid form of the peptidic hormone apelin (AP-13) as a candidate for systemic stimulation of skeletal muscle ECs. In dystrophic mice, administration of AP-13 generates a pro-myogenic EC-rich niche that supports MuSC function and markedly improves tissue regeneration, muscle strength, and physical performance. Moreover, we demonstrate that EC specific knockout of the AP-13 receptor leads to regenerative defects that phenocopy major pathological features of MD. Altogether, we provide in vivo proof-of-concept that enhancing endogenous repair by targeting the perivascular niche is a viable therapeutic avenue for MD and characterize AP-13 as a novel drug candidate for systemic treatment of stem cell dysfunction.

cell biology↗

bioRxiv2021

Optogenetic stimulation of glutamatergic neurons in the cuneiform nucleus controls locomotor movements in a mouse model of Parkinson's disease

In Parkinsons disease (PD), the loss of midbrain dopaminergic cells results in severe locomotor deficits such a gait freezing and akinesia. Growing evidence indicates that these deficits can be attributed to decreased activity in the Mesencephalic Locomotor Region (MLR), a brainstem region controlling locomotion. Clinicians are exploring deep brain stimulation of the MLR as a treatment option to improve locomotor function. The results are variable, from modest to promising. However, within the MLR, clinicians have targeted the pedunculopontine nucleus exclusively, while leaving the cuneiform nucleus unexplored. To our knowledge, the effects of cuneiform nucleus stimulation have never been determined in parkinsonian conditions in any animal model. Here, we addressed this issue in a mouse model of Parkinsons disease based on bilateral striatal injection of 6-hydroxydopamine (6-OHDA), which damaged the nigrostriatal pathway and decreased locomotor activity. We show that selective optogenetic stimulation of glutamatergic neurons in the cuneiform nucleus in mice expressing channelrhodopsin in a Cre-dependent manner in Vglut2-positive neurons (Vglut2-ChR2-EYFP mice) increased the number of locomotor initiations, increased the time spent in locomotion, and controlled locomotor speed. Using deep learning-based movement analysis, we found that limb kinematics of optogenetic-evoked locomotion in pathological conditions were largely similar to those recorded in freely moving animals. Our work identifies the glutamatergic neurons of the cuneiform nucleus as a potentially clinically relevant target to improve locomotor activity in parkinsonian conditions. Our study should open new avenues to develop targeted stimulation of these neurons using deep brain stimulation, pharmacotherapy or optogenetics. SIGNIFICANCE STATEMENTIn Parkinsons disease, alleviating locomotor deficits is a challenge. Clinicians are exploring deep brain stimulation of the Mesencephalic Locomotor Region, a brainstem region controlling locomotion, but results are mixed. However, the best target in this region in Parkinsons disease remains unknown. Indeed, this region which comprises the pedunculopontine and cuneiform nuclei, contains different cell types with opposing effects on locomotor output. Here, using a mouse model where midbrain dopaminergic cells were damaged by a neurotoxin, we demonstrate that optogenetic activation of glutamatergic neurons in the cuneiform nucleus increases locomotion, controls speed, and evokes limb movements similar to those observed during spontaneous locomotion in intact animals. Our study identifies a potentially clinically relevant target to improve locomotor function in Parkinsons disease.

neuroscience↗

bioRxiv2020

Freely behaving mice can brake and turn during optogenetic stimulation of the Mesencephalic Locomotor Region

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSBackgroundC_ST_ABSStimulation of the Mesencephalic Locomotor Region (MLR) is increasingly considered as a target to improve locomotor function in Parkinsons disease, spinal cord injury and stroke. A key function of the MLR is to control the speed of forward symmetrical locomotor movements. However, the ability of freely moving mammals to integrate environmental cues to brake and turn during MLR stimulation is poorly documented. Objective/hypothesisWe investigated whether freely behaving mice could brake or turn based on environmental cues during MLR stimulation. MethodsWe stimulated the cuneiform nucleus in mice expressing channelrhodopsin in Vglut2-positive neurons in a Cre-dependent manner (Vglut2-ChR2-EYFP) using optogenetics. We detected locomotor movements using deep learning. We used patch-clamp recordings to validate the functional expression of channelrhodopsin and neuroanatomy to visualize the stimulation sites. ResultsOptogenetic stimulation of the MLR evoked locomotion and increasing laser power increased locomotor speed. Gait diagram and limb kinematics were similar during spontaneous and optogenetic-evoked locomotion. Mice could brake and make sharp turns ([~]90) when approaching a corner during MLR stimulation in an open-field arena. The speed during the turn was scaled with the speed before the turn, and with the turn angle. In a reporter mouse, many Vglut2-ZsGreen neurons were immunopositive for glutamate in the MLR. Patch-clamp recordings in Vglut2-ChR2-EYFP mice show that blue light evoked short latency spiking in MLR neurons. ConclusionMLR glutamatergic neurons are a relevant target to improve locomotor activity without impeding the ability to brake and turn when approaching an obstacle, thus ensuring smooth and adaptable navigation. HO_SCPLOWIGHLIGHTSC_SCPLOW- Mice brake and turn when approaching the arenas corner during MLR-evoked locomotion - Speed decrease is scaled to speed before the turn during MLR-evoked locomotion - Turn angle is scaled to turn speed during MLR-evoked locomotion - Gait and limb kinematics are similar during spontaneous and MLR-evoked locomotion

neuroscience↗

bioRxiv2018

Neurotensin and Dynorphin Bi-Directionally Modulates CeA Inhibition of oval BNST Neurons in Male Mice

Neuropeptides are often co-expressed in neurons but their neurophysiological effects are commonly studied individually. Multiple neuropeptides may therefore be simultaneously released to coordinate proper neural circuit function. Here, we triggered the release of endogenous neuropeptides in brain slices from male mice to better understand the modulation of central amygdala (CeA) inhibitory inputs onto oval (ov) BNST neurons. We found that locally-released neurotensin (NT) and dynorphin (Dyn) antagonistically regulated CeA inhibitory inputs onto ovBNST neurons. NT and Dyn respectively increased and decreased CeA-to-ovBNST inhibitory inputs through NT receptor 1 (NTR1) and kappa opioid receptor (KOR). Additionally, NT and Dyn mRNAs were highly co-localized in ovBNST neurons suggesting that they may be released from the same cells. Together, we showed that NT and Dyn are key modulators of CeA inputs to ovBNST, paving the way to determine whether different conditions or states can alter the neuropeptidergic regulation of this particular brain circuit.

neuroscience↗

bioRxiv2016

Analgesic effects of neurotensin agonists in a rat bone cancer pain model

Bone metastases are a source of intractable pain, resistant to conventional opioid and non-opioid analgesics. The neurotensin system represents a potential pathway toward bone cancer pain (BCP) relieve via the inhibition of its receptors NTS1 and NTS2. Capitalizing on our recent results using neurotensin analogs in inflammatory and neuropathic pain models, we here show, for the first time, a potential role for neurotensin receptors agonists in the treatment of BCP. The novel non-selective agonist JMV-2009 (300 g/kg) reversed mechanical allodynia in our rodent BCP model at both early and late stages of the disease. The NTS2-selective agonist JMV-431 (90 g/kg), in addition to anti-allodynia, also had an effect on weight bearing deficits. In parallel, we tested proven analgesics from several classes to put the effect of neurotensin analogs in perspective and found that morphine (3 mg/kg), tramadol (15 mg/kg) and amitriptyline (10 mg/kg) had mild effects on BCP while the cannabinoid nabilone (1 mg/kg) significantly reversed both allodynia and weight bearing deficits. Taken together, our results affirm the potential of the modulation of the neurotensin system for the development of new analgesics for the treatment of bone cancer pain.

pharmacology and toxicology↗