Inflammation condition sensitizes Piezo1 mechanosensitive channel in mouse cerebellum astrocyte

Piezo1 is a pathogenic gene and therapeutic target for neurological diseases

Piezo1 is a ubiquitously expressed non-selective cation channel protein found across various species. It possesses the ability to detect and respond to external mechanical forces, converting mechanical cues into intracellular bioelectrical events, thereby facilitating the propagation of electrochemical signals. Within the nervous system, Piezo1 is integral to synaptogenesis and myelination, modulation of pro-inflammatory mediators, neuropathic pain, cognitive processes, angiogenesis, and the regulation of cerebral hemodynamics, consequently impacting the pathogenesis and progression of neurological disorders. This review meticulously summarizes and synthesizes existing literature to provide an exhaustive overview of Piezo1's roles and mechanisms in a spectrum of neurological diseases, including neurodegenerative disorders, cerebrovascular accidents, traumatic brain injuries, gliomas, multiple sclerosis, and epilepsy. Additionally, it explores the potential therapeutic applications of targeting Piezo1. The discussion also encompasses the current research limitations, the imperative need for future investigations, and prospective strategies. Our analysis indicates that Piezo1 is a susceptibility gene for neurological conditions, and its expression inhibition may confer therapeutic benefits. In summary, this comprehensive review offers novel insights into the involvement of Piezo1 in neurological diseases and establishes a theoretical groundwork for the future development of Piezo1-targeted therapeutic interventions.

Calcium-Dependent Signaling in Astrocytes: Downstream Mechanisms and Implications for Cognition

Astrocytes are glial cells recognized for their diverse roles in regulating brain circuit structure and function. They can sense and adapt to changes in the microenvironment due to their unique structural and biochemical properties. A key aspect of astrocytic function involves calcium (Ca2+)-dependent signaling, which serves as a fundamental mechanism for their interactions with neurons and other cells in the brain. However, while significant progress has been made in understanding the spatio-temporal properties of astrocytic Ca2+ signals, the downstream molecular pathways and exact mechanisms through which astrocytes decode these signals to regulate homeostatic and physiological processes remain poorly understood. To address this topic, we review here the available literature on the sources of intracellular Ca2+, as well as its downstream mechanisms and signaling pathways. We review the well-studied Ca2+-dependent exocytosis but draw attention to additional intracellular Ca2+-dependent mechanisms that are less understood and are, most likely, highly influential for many other cellular functions. Finally, we review how intracellular Ca2+ is thought to underlie neuron-astrocyte signaling in brain regions involved in cognitive processing.

GsMTx-4 combined with exercise improves skeletal muscle structure and motor function in rats with spinal cord injury

Motor dysfunction and muscle atrophy are typical symptoms of patients with spinal cord injury (SCI). Exercise training is a conventional physical therapy after SCI, but exercise intervention alone may have limited efficacy in reducing secondary injury and promoting nerve regeneration and functional remodeling. Our previous research found that intramedullary pressure after SCI is one of the key factors affecting functional prognosis. It has been reported that GsMTx-4, a specific blocker of the mechanosensitive ion channels Piezo1, can protect the integrity of the neuromuscular junction and promote nerve regeneration, and thus has the potential as a therapeutic agent for SCI. In this study, we observed the combined and separate therapeutic effect of GsMTx-4 and exercise on the structure of the soleus muscle and motor function in rats with SCI. At 42 days post-injury, compared with SCI rats, the Basso-Beattie-Bresnahan score (P = 0.0007) and Gait Symmetry (P = 0.0002) were significantly improved after combination therapy. On histology of rat soleus muscle, compared with SCI rats, the combined treatment significantly increased the wet weight ratio, muscle fiber cross-sectional area and acetylcholinesterase (all P<0.0001). On histology of rat spinal tissue, compared with SCI rats, the combined treatment significantly increased neuron counts and BDNF levels, and significantly reduced the percentage of TUNEL-positive cells (all P<0.0001). On physiology of rat soleus muscle, compared with SCI rats, the combined treatment increased the succinate dehydrogenase expression (P<0.0001), while the expression of α-glycerophosphate dehydrogenase (P<0.0001) and GDF8 protein (P = 0.0008) decreased. Results indicate the combination therapy effectively improves histopathology of spinal cord and soleus muscle in SCI rats, enhancing motor function. This study was conducted on animal models, it offers insights for SCI treatment, advancing understanding of lower limb muscle pathology post-SCI. Further research is needed for clinical validation in the future.

GsMTx4 Combined with Exercise Exerts Neuroprotective Effects by Regulating Neuronal Autophagy in Rats with Spinal Cord Injury

A sharp increase in intramedullary pressure after spinal cord injury (SCI) can aggravate secondary injury and lead to severe neurological deficits. Unfortunately, effective treatment options are currently lacking. The mechanosensitive ion channel Piezo1 plays an important role in the pathological process of SCI by transducing mechanical stress. The Piezo1 inhibitor GsMTx4 has been shown to have neuroprotective effects and may hold therapeutic potential for SCI. Given that single drug treatment strategy has limited effect on functional recovery after SCI, we explored the efficacy of combining GsMTx4 with exercise training in treating SCI in rats and investigated the underlying mechanisms. We used the T10 SCI rat model, administered GsMTx4 immediately after injury, and performed 4 weeks of body weight supported treadmill training starting (BWSTT) 2 weeks post injury. Subsequently, HE and LFB staining were used to observe the morphology of spinal cord tissue, WB was used to detect autophagy and apoptosis-related proteins, biochemical detection of calcium ion concentration and CTSD activity, IHC detection of LAMP1 expression, immunofluorescence labeling of NeuN and ChAT-positive motor neurons, as well as MBP and GFAP, and BBB scores were used to evaluate rat motor function. We found that the combined treatment of GsMTx4 drug and exercise training was more effective than single treatment alone. The combined treatment reduced calcium ion concentration, improved lysosomal function, enhanced autophagic flux, reduced cell apoptosis, and significantly improved the motor function of rats. This combined treatment regimen may pave the way for developing more comprehensive treatment strategies for SCI in the future.

DISTINCT PATTERNS OF ENDOTHELIAL CELL ACTIVATION PRODUCED BY EXTRACELLULAR HISTONES AND BACTERIAL LIPOPOLYSACCHARIDE

ABSTRACT

Objective : Vascular endothelial cells (ECs) sense and respond to both trauma factors (histone proteins) and sepsis signals (bacterial lipopolysaccharide, LPS) with elevations in calcium (Ca 2+ ), but it is not clear if the patterns of activation are similar or different. We hypothesized that within seconds of exposure, histones but not LPS would produce a large EC Ca 2+ response. We also hypothesized that histones would produce different spatio-temporal patterns of Ca 2+ events in veins than in arteries. Methods : We studied cultured ECs (EA.hy926) and native endothelial cells from surgically opened murine blood vessels. High-speed live cell imaging of Ca 2+ events were acquired for 5 min before and after stimulation of cultured ECs with histones or LPS alone or in combination. Histone-induced EC Ca 2+ events were also compared in native endothelial cells from resistance-sized arteries and veins. Ca 2+ activity was quantified as "Ca 2+ prevalence" using custom spatiotemporal analysis. Additionally, cultured ECs were collected after 6 h of exposure to histones or LPS for RNA sequencing. Results : ECs-both in culture and in blood vessels-rapidly increased Ca 2+ activity within seconds of histone exposure. In contrast, LPS exposure produced only a slight increase in Ca 2+ activity in cultured ECs and no effect on blood vessels over 5-min recording periods. Histones evoked large aberrant Ca 2+ events (>30 s in duration) in both veins and arteries, but with different spatio-temporal patterns. Ca 2+ activity in arterial ECs often appeared as "rosettes", with Ca 2+ events that propagated from one cell to all adjacent surrounding cells. In veins, ECs responded individually without spreading. Surprisingly, exposure of cultured ECs to LPS for 5 min before histones potentiated EC Ca 2+ activity by an order of magnitude. Exposure of ECs to histones or LPS both increased gene expression, but different mRNAs were induced. Conclusions : LPS and histones activate ECs through mechanisms that are distinct and additive; only histones produce large aberrant Ca 2+ events. ECs in arteries and veins display different patterns of Ca 2+ responses to histones.

Research progress on the immunological functions of Piezo1 a receptor molecule that responds to mechanical force

The human immune system is capable of defending against, monitoring, and self-stabilizing various immune cells. Differentiation, proliferation, and development of these cells are regulated by biochemical signals. Moreover, biophysical signals, such as mechanical forces, have been found to affect immune cell function, thus introducing a new area of immunological research. Piezo1, a mechanically sensitive ion channel, was awarded the Nobel Prize for Physiology and Medicine in 2021. This channel is present on the surface of many cells, and when stimulated by mechanical force, it controls calcium (Ca2+) inside the cells, leading to changes in downstream signals and thus regulating cell functions. Piezo1 is also expressed in various innate and adaptive immune cells and plays a major role in the immune function. In this review, we will explore the physiological functions and regulatory mechanisms of Piezo1 and its impact on innate and adaptive immunity. This may offer new insights into diagnostics and therapeutics for the prevention and treatment of diseases and surgical infections.

Satellite Glial Cells Bridge Sensory Neuron Crosstalk in Visceral Pain and Cross-Organ Sensitization

Following colonic inflammation, the uninjured bladder afferent neurons are also activated. The mechanisms and pathways underlying this sensory neuron cross-activation (from injured neurons to uninjured neurons) are not fully understood. Colonic and bladder afferent neurons reside in the same spinal segments and are separated by satellite glial cells (SGCs) and extracellular matrix in dorsal root ganglia (DRG). SGCs communicate with sensory neurons in a bidirectional fashion. This review summarizes the differentially regulated genes/proteins in the injured and uninjured DRG neurons and explores the role of SGCs in regulation of sensory neuron crosstalk in visceral cross-organ sensitization. The review also highlights the paracrine pathways in mediating neuron-SGC and SGC-neuron coupling with an emphasis on the neurotrophins and purinergic systems. Finally, I discuss the results from recent RNAseq profiling of SGCs to reveal useful molecular markers for characterization, functional study, and therapeutic targets of SGCs. SIGNIFICANCE STATEMENT: Satellite glial cells (SGCs) are the largest glial subtypes in sensory ganglia and play a critical role in mediating sensory neuron crosstalk, an underlying mechanism in colon-bladder cross-sensitization. Identification of novel and unique molecular markers of SGCs can advance the discovery of therapeutic targets in treatment of chronic pain including visceral pain comorbidity.

Microglial Piezo1 mechanosensitive channel as a therapeutic target in Alzheimer's disease

Microglia are the resident macrophages of the central nervous system (CNS) that control brain development, maintain neural environments, respond to injuries, and regulate neuroinflammation. Despite their significant impact on various physiological and pathological processes across mammalian biology, there remains a notable gap in our understanding of how microglia perceive and transmit mechanical signals in both normal and diseased states. Recent studies have revealed that microglia possess the ability to detect changes in the mechanical properties of their environment, such as alterations in stiffness or pressure. These changes may occur during development, aging, or in pathological conditions such as trauma or neurodegenerative diseases. This review will discuss microglial Piezo1 mechanosensitive channels as potential therapeutic targets for Alzheimer's disease (AD). The structure, function, and modulation of Piezo1 will be discussed, as well as its role in facilitating microglial clearance of misfolded amyloid-β (Aβ) proteins implicated in the pathology of AD.

ω3-PUFA alleviates neuroinflammation by upregulating miR-107 targeting PIEZO1/NFκB p65

BACKGROUND

MiR-107 is reduced in sepsis and associated with inflammation regulation. Dietary supplementation with polyunsaturated fatty acids (ω3-PUFA) can increase the expression of miR-107; this study investigated whether the ω3-PUFA can effectively inhibit neuroinflammation and improve cognitive function by regulating miR-107 in the brain.

METHODS

The LPS-induced mouse model of neuroinflammation and the BV2 cell inflammatory model were used to evaluate the effects of ω3-PUFA on miR-107 expression and inflammation. Intraventricular injection of Agomir and Antagomir was used to modulate miR-107 expression. HE and Nissl staining for analyzing hippocampal neuronal damage, immunofluorescence analysis for glial activation, RT-qPCR, and Western blot were conducted to examine miR-107 expression and inflammation signalling.

RESULTS

The result shows that LPS successfully induced the mouse neuroinflammation model and BV2 cell inflammation model. Supplementation of ω3-PUFA effectively reduced the secretion of pro-inflammatory factors TNFα, IL1β, and IL6 induced by LPS, improved cognitive function impairment, and increased miR-107 expression in the brain. Overexpression of miR-107 in the brain inhibited the nuclear factor κB (NFκB) pro-inflammatory signalling pathway by targeting PIEZO1, thus suppressing microglial and astrocyte activation and reducing the release of inflammatory mediators, which alleviated neuroinflammatory damage and improved cognitive function in mice. miR-107, as an intron of PANK1, PANK1 is subject to PPAR α Adjust. ω3-PUFA can activate PPARα, but ω3-PUFA upregulates brain miR-107, and PPARα/PANK1-related pathways may not be synchronized, and further research is needed to confirm the specific mechanism by which ω3-PUFA upregulates miR-107.

CONCLUSION

The miR-107/PIEZO1/NFκB p65 pathway represents a novel mechanism underlying the improvement of neuroinflammation by ω3-PUFA.

Pharmacological Activation of Piezo1 Channels Enhances Astrocyte-Neuron Communication via NMDA Receptors in the Murine Neocortex

The Piezo1 mechanosensitive ion channel is abundant on several elements of the central nervous system including astrocytes. It has been already demonstrated that activation of these channels is able to elicit calcium waves on astrocytes, which contributes to the release of gliotransmitters. Astrocyte- and N-methyl-D-aspartate (NMDA) receptor-dependent slow inward currents (SICs) are hallmarks of astrocyte-neuron communication. These currents are triggered by glutamate released as gliotransmitter, which in turn activates neuronal NMDA receptors responsible for this inward current having slower kinetics than any synaptic events. In this project, we aimed to investigate whether Piezo1 activation and inhibition is able to alter spontaneous SIC activity of murine neocortical pyramidal neurons. When the Piezo1 opener Yoda1 was applied, the SIC frequency and the charge transfer by these events in a minute time was significantly increased. These changes were prevented by treating the preparations with the NMDA receptor inhibitor D-AP5. Furthermore, Yoda1 did not alter the spontaneous EPSC frequency and amplitude when SICs were absent. The Piezo1 inhibitor Dooku1 effectively reverted the actions of Yoda1 and decreased the rise time of SICs when applied alone. In conclusion, activation of Piezo1 channels is able to alter astrocyte-neuron communication. Via enhancement of SIC activity, astrocytic Piezo1 channels have the capacity to determine neuronal excitability.

Piezo1 as a potential player in intracranial hemorrhage: from perspectives on biomechanics and hematoma metabolism

Intracranial hemorrhage (ICH) causes numerous neurological deficits and deaths worldwide each year, leaving a significant health burden on the public. The pathophysiology of ICH is complicated, and involves both primary and secondary injury. Hematoma, as the prime pathology of ICH, undergoes metabolism and triggers biochemical and biomechanical alterations in the brain, leading to secondary injury. Past endeavors mainly aimed at biochemical-initiated mechanisms for causing secondary injury have made limited progress in recent years, although ICH itself is also highly biomechanics-related. The discovery of the mechanical-activated cation channel Piezo1 provides a new avenue to further explore underlying mechanisms of secondary injury. The current article reviews the structure and gating mechanisms of Piezo1, its roles in the physiology/pathophysiology of neurons, astrocytes, microglia, and bone-marrow-derived macrophages, and especially its roles in erythrocytic turnover and iron metabolism, revealing a potential interplay between the biomechanics and biochemistry of hematoma in ICH. Collectively, these advances provide deeper insights into the secondary injury of ICH and lay the foundations for future research.

Mechanosensitive Piezo1 channel in physiology and pathophysiology of the central nervous system

Since the discovery of the mechanosensitive Piezo1 channel in 2010, there has been a significant amount of research conducted to explore its regulatory role in the physiology and pathology of various organ systems. Recently, a growing body of compelling evidence has emerged linking the activity of the mechanosensitive Piezo1 channel to health and disease of the central nervous system. However, the exact mechanisms underlying these associations remain inadequately comprehended. This review systematically summarizes the current research on the mechanosensitive Piezo1 channel and its implications for central nervous system mechanobiology, retrospects the results demonstrating the regulatory role of the mechanosensitive Piezo1 channel on various cell types within the central nervous system, including neural stem cells, neurons, oligodendrocytes, microglia, astrocytes, and brain endothelial cells. Furthermore, the review discusses the current understanding of the involvement of the Piezo1 channel in central nervous system disorders, such as Alzheimer's disease, multiple sclerosis, glaucoma, stroke, and glioma.