Inflammatory Signaling via PEIZO1 Engages and Enhances the LPS-Mediated Apoptosis during Clinical Mastitis.

Bovine clinical mastitis is characterized by inflammation and immune responses, with apoptosis of mammary epithelial cells as a cellular reaction to infection. PIEZO1, identified as a mechanotransduction effector channel in nonruminant animals and sensitive to both mechanical stimuli or inflammatory signals like lipopolysaccharide (LPS). However, its role in inflammatory processes in cattle has not been well-documented. The aim of this study was to elucidate the in situ expression of PIEZO1 in bovine mammary gland and its potential involvement in clinical mastitis. We observed widespread distribution and upregulation of PIEZO1 in mammary epithelial cells in clinical mastitis cows and LPS-induced mouse models, indicating a conserved role across species. In vitro studies using mammary epithelial cells (MAC-T) revealed that LPS upregulates PIEZO1. Notably, the effects of PIEZO1 artificial activator Yoda1 increased apoptosis and NLRP3 expression, effects mitigated by PIEZO1 silencing or NLRP3 inhibition. In conclusion, the activation of the PIEZO1-NLRP3 pathway induces abnormal apoptosis in mammary epithelial cells, potentially serving as a regulatory mechanism to combat inflammatory responses to abnormal stimuli.

Lithospermic acid improves liver fibrosis through Piezo1-mediated oxidative stress and inflammation.

BACKGROUND: Hepatic fibrosis is becoming an increasingly serious public health issue worldwide. Although liver transplantation is the only and definitive treatment for end-stage liver fibrosis, traditional Chinese medicine offers certain benefits in the treatment of advanced hepatic fibrosis. PURPOSE: This study aims to explore the protective effect of lithospermic acid (LA), an extraction from Salvia miltiorrhiza (the roots of S. miltiorrhiza Bunge, known as Danshen in Chinese), on liver fibrosis and investigate its potential mechanisms. METHODS AND RESULTS: Mice were treated with carbon tetrachloride (CCl4) via intraperitoneal injection for 4 weeks. LA was orally administered or colchicine (COL) was injected intraperitoneally for 3 weeks starting one week after the initial CCl4 injection. After the LA treatment, we observed a decrease in the fibrosis index and an improvement in liver function. Molecular docking results revealed that Piezo1 may be a potential pharmacological target of LA. The further experimental results showed that LA inhibited Piezo1 activation and expression in macrophages. Mechanistically, both Piezo1/Notch-mediated inflammation and oxidative stress regulated by the Piezo1/Ca2+ pathway were alleviated in fibrotic livers following LA treatment. Moreover, less oxidative stress and Notch activation were observed in the deficiency of macrophage Piezo1 (Piezo1ΔLysM) mice. In addition, Piezo1ΔLysM partially counteracted the pharmacological effects of LA on liver fibrosis. CONCLUSION: In conclusion, our present study corroborated LA limits the progression of liver fibrosis by regulating Piezo1-mediated oxidative stress and inflammation. These results indicate that LA could be a potential medication for hepatic fibrosis treatment.

Mechanical regulation of lipid and sugar absorption by Piezo1 in enterocytes.

Obesity is primarily caused by excessive intake as well as absorption of sugar and lipid. Postprandial surge in distention pressure and intestinal motility accelerates the absorption of nutrients. The response of intestinal epithelial cells to mechanical stimulation is not fully understood. Piezo1, a mechanosensitive ion channel, is widely expressed throughout the digestive tract. However, its function in intestinal nutrient absorption is not yet clear. In our study, excessive lipid deposition was observed in the duodenum of obese patients, while duodenal Piezo1-CaMKK2-AMPKα was decreased when compared to normal-weight individuals. Under high-fat diet condition, the Piezo1 iKO mice exhibited abnormally elevated sugar and lipid absorption as well as severe lipid deposition in the duodenum and liver. These phenotypes were mainly caused by the inhibition of duodenal CaMKK2-AMPKα and the upregulation of SGLT1 and DGAT2. In contrast, Yoda1, a Piezo1 agonist, was found to reduce intestinal lipid absorption in diet induced obese mice. Overexpression of Piezo1, stretch and Yoda1 inhibited lipid accumulation and the expression of DGAT2 and SGLT1, whereas knockdown of Piezo1 stimulated lipid accumulation and DGAT2 in Caco-2 cells. Our study reveals a previously unexplored mechanical regulation of nutrient absorption in intestinal epithelial cells, which may shed new light on the therapy of obesity.

Strontium zinc silicate simultaneously alleviates osteoporosis and sarcopenia in tail-suspended rats via Piezo1-mediated Ca2+ signaling.

Background: Long-term physical inactivity probably leads to a co-existence of osteoporosis and sarcopenia which result in a high risk of falls, fractures, disability and even mortality. However, universally applicable and feasible approaches are lacking in the concurrent treatment of osteoporosis and sarcopenia. In this study, we evaluated the effect of strontium zinc silicate bioceramic (SZS) extract on osteoporosis and sarcopenia and explored its underlying mechanisms. Methods: Hindlimb osteoporosis and sarcopenia were established in a tail-suspended rat model. The bones were conducted µCT scanning, histological examination, and gene expression analysis, and the muscles were conducted histological examination and gene expression analysis. In vitro, the effect of SZS extract on osteoblasts was determined by alizarin red S staining, immunofluorescence and qPCR. Similarly, the effect of SZS extract on myoblasts was determined by immunofluorescence and qPCR.. At last, the role of Piezo1 and the change of intracellular calcium ion (Ca2+) were explored through blockading the Piezo1 by GsMTx4 in MC3T3-E1 and C2C12 cells, respectively. Results: We found that SZS extract could concurrently and efficiently prevent bone structure deterioration, muscle atrophy and fibrosis in hind limbs of the tail-suspended rats. The in vivo study also showed that SZS extract could upregulate the mRNA expression of Piezo1, thereby maintaining the homeostasis of bones and muscles. In vitro study demonstrated that SZS extract could promote the proliferation and differentiation of MC3T3-E1 and C2C12 cells by increasing the intracellular Ca2+ in a Piezo1-dependent manner. Conclusion: This study demonstrated that SZS extract could increase Piezo1-mediated intracellular Ca2+, and facilitate osteogenic differentiation of osteoblast and myogenic differentiation of myoblasts, contributing to alleviation of osteoporosis and sarcopenia in a tail-suspended rat model. The translational potential of this article: The current study might provide a universally applicable and efficient strategy to treat musculoskeletal disorders based on bioactive ceramics. The verification of the role of Piezo1-modulated intracellular Ca2+ during osteogenesis and myogenesis provided a possible therapeutic target against mechanical related diseases.

Piezo1 activation on microglial cells exacerbates demyelination in sepsis by influencing the CCL25/GRP78 pathway.

BACKGROUND: In sepsis-associated encephalopathy (SAE), the activation of microglial cells and ensuing neuroinflammation are important in the underlying pathological mechanisms. Increasing evidence suggests that the protein Piezo1 functions as a significant regulator of neuroinflammation. However, the influence of Piezo1 on microglial cells in the context of SAE has not yet been determined. This study aims to investigate the role of Piezo1 in microglial cells in the context of SAE. METHODS: By inducing cecal ligation and puncture (CLP), a mouse model of SAE was established, while the control group underwent a sham surgery in which the cecum was exposed without ligation and puncture. Piezo1 knockout mice were employed in this study. Morris water maze tests were conducted between Days 14 and 18 postop to assess both the motor activity and cognitive function. A proteomic analysis was conducted to assess the SAE-related pathways, whereas a Mendelian randomization analysis was conducted to identify the pathways associated with cognitive impairment. Dual-label immunofluorescence and flow cytometry were used to assess the secretion of inflammatory factors, microglial status, and oligodendrocyte development. Electron microscopy was used to evaluate axonal myelination. A western blot analysis was conducted to evaluate the influence of Piezo1 on oligodendrocyte ferroptosis. RESULTS: The results of the bioinformatics analysis have revealed the significant involvement of CCL25 in the onset and progression of SAE-induced cognitive impairment. SAE leads to cognitive dysfunction by activating the microglial cells. The release of CCL25 by the activated microglia initiates the demyelination of oligodendrocytes in the hippocampus, resulting in ferroptosis and the disruption of hippocampal functional connectivity. Of note, the genetic knockout of the Piezo1 gene mitigates these changes. The treatment with siRNA targeting Piezo1 effectively reduces the secretion of inflammatory mediators CCL25 and IL-18 by inhibiting the p38 pathway, thus preventing the ferroptosis of oligodendrocytes through the modulation of the CCL25/GPR78 axis. CONCLUSION: Piezo1 is involved in the activation of microglia and demyelinating oligodendrocytes in the animal models of SAE, resulting in cognitive impairment. Consequently, targeting Piezo1 suppression can be a promising approach for therapeutic interventions aimed at addressing cognitive dysfunction associated with SAE.

Activation of Piezo1 channels enhances spontaneous contractions of isolated human bladder strips via acetylcholine release from the mucosa.

Enhanced spontaneous bladder contractions (SBCs) have been thought one of the important underlying mechanisms for detrusor overactivity (DO). Piezo1 channel has been demonstrated involved in bladder function and dysfunction in rodents. We aimed to investigate the modulating role of Piezo1 in SBCs activity of human bladder. Human bladder tissues were obtained from 24 organ donors. SBCs of isolated bladder strips were recorded in organ bath. Piezo1 expression was examined with reverse transcription-quantitative polymerase chain reaction and immunofluorescence staining. ATP and acetylcholine release in cultured human urothelial cells was measured. Piezo1 is abundantly expressed in the bladder mucosa. Activation of Piezo1 with its specific agonist Yoda1 (100nM to 100µM) enhanced the SBCs activity in isolated human bladder strips in a concentration-dependent manner. The effect of Yoda1 mimicked the effect of a low concentration (30nM) of carbachol, which can be attenuated by removing the mucosa, blocking muscarinic receptors with atropine (1µM), and blocking purinergic receptors with pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (10µM), but not by tetrodotoxin (1µM). Activation of urothelial Piezo1 with Yoda1 (30µM) or hypotonic solution induced the release of ATP and acetylcholine in cultured human urothelial cells. In patients with benign prostatic hyperplasia, greater Piezo1 expression was observed in bladder mucosa from patients with DO than patients without DO. We conclude that upregulation and activation of Piezo1 may contribute to DO generation in patients with bladder outlet obstruction by promoting the urothelial release of ATP and acetylcholine. Inhibition of Piezo1 may be a novel therapeutic approach in the treatment of overactive bladder.

Piezo ion channels: long-sought-after mechanosensors mediating hypertension and hypertensive nephropathy.

Recent advances in mechanobiology and the discovery of mechanosensitive ion channels have opened a new era of research on hypertension and related diseases. Piezo1 and Piezo2, first reported in 2010, are regarded as bona fide mechanochannels that mediate various biological and pathophysiological phenomena in multiple tissues and organs. For example, Piezo channels have pivotal roles in blood pressure control, triggering shear stress-induced nitric oxide synthesis and vasodilation, regulating baroreflex in the carotid sinus and aorta, and releasing renin from renal juxtaglomerular cells. Herein, we provide an overview of recent literature on the roles of Piezo channels in the pathogenesis of hypertension and related kidney damage, including our experimental data on the involvement of Piezo1 in podocyte injury and that of Piezo2 in renin expression and renal fibrosis in animal models of hypertensive nephropathy. The mechanosensitive ion channels Piezo1 and Piezo2 play various roles in the pathogenesis of systemic hypertension by acting on vascular endothelial cells, baroreceptors in the carotid artery and aorta, and the juxtaglomerular apparatus. Piezo channels also contribute to hypertensive nephropathy by acting on mesangial cells, podocytes, and perivascular mesenchymal cells.

Hyperbaric oxygen promotes bone regeneration by activating the mechanosensitive Piezo1 pathway in osteogenic progenitors.

Background: Hyperbaric oxygen (HBO) therapy is widely used to treat bone defects, but the correlation of high oxygen concentration and pressure to osteogenesis is unclear. Methods: Bilateral monocortical tibial defect surgeries were performed on 12-week-old Prrx1-Cre; Rosa26-tdTomato and Prrx1-Cre; Piezo1fl/+ mice. Daily HBO treatment was applied on post-surgery day (PSD) 1-9; and daily mechanical loading on tibia was from PSD 5 to 8. The mice were euthanized on PSD 10, and bone defect repair in their tibias was evaluated using µCT, biomechanical testing, and immunofluorescence deep-tissue imaging. The degree of angiogenesis-osteogenesis coupling was determined through spatial correlation analysis. Bone marrow stromal cells from knockout mice were cultured in vitro, and their osteogenic capacities of the cells were assessed. The activation of genes in the Piezo1-YAP pathway was evaluated using RNA sequencing and quantitative real-time polymerase chain reaction. Results: Lineage tracing showed HBO therapy considerably altered the number of Prrx1+ cells and their progeny in a healing bone defect. Using conditional knockdown mice, we found that HBO stimulation activates the Piezo1-YAP axis in Prrx1+ cells and promotes osteogenesis-angiogenesis coupling during bone repair. The beneficial effect of HBO was similar to that of anabolic mechanical stimulation, which also acts through the Piezo1-YAP axis. Subsequent transcriptome sequencing results revealed that similar mechanosensitive pathways are activated by HBO therapy in a bone defect. Conclusion: HBO therapy promotes bone tissue regeneration through the mechanosensitive Piezo1-YAP pathway in a population of Prrx1+ osteogenic progenitors. Our results contribute to the understanding of the mechanism by which HBO therapy treats bone defects. The Translational Potential of this Article: Hyperbaric oxygen therapy is widely used in clinical settings. Our results show that osteogenesis was induced by the activation of the Piezo1-YAP pathway in osteoprogenitors after HBO stimulation, and the underlying mechanism was elucidated. These results may help improve current HBO methods and lead to the formulation of alternative treatments that achieve the same functional outcomes.

PIEZO1 targeting in macrophages boosts phagocytic activity and foam cell apoptosis in atherosclerosis.

The rising incidences of atherosclerosis have necessitated efforts to identify novel targets for therapeutic interventions. In the present study, we observed increased expression of the mechanosensitive calcium channel Piezo1 transcript in mouse and human atherosclerotic plaques, correlating with infiltration of PIEZO1-expressing macrophages. In vitro administration of Yoda1, a specific agonist for PIEZO1, led to increased foam cell apoptosis and enhanced phagocytosis by macrophages. Mechanistically, PIEZO1 activation resulted in intracellular F-actin rearrangement, elevated mitochondrial ROS levels and induction of mitochondrial fragmentation upon PIEZO1 activation, as well as increased expression of anti-inflammatory genes. In vivo, ApoE-/- mice treated with Yoda1 exhibited regression of atherosclerosis, enhanced stability of advanced lesions, reduced plaque size and necrotic core, increased collagen content, and reduced expression levels of inflammatory markers. Our findings propose PIEZO1 as a novel and potential therapeutic target in atherosclerosis.

Mechanosensitive Piezo1 channels promote neurogenic bladder fibrosis via regulating TGF-ß1/smad and Hippo/YAP1 pathways.

Bladder fibrosis is the final common pathway of neurogenic bladder (NB), and its underlying mechanisms are not fully understood. The current study aims to evaluate the involvement of Piezo1, a mechanosensitive channel, in bladder fibrosis. A full-thickness bladder specimen was taken during ileocystoplasty or ureteral reimplantation from the surgical cut's edge. By chopping off the bilateral lumbar 6 (L6) and sacral 1 (S1) spinal nerves, NB rat models were produced. Utilizing both pharmacological inhibition and Piezo1 deletion, the function of Piezo1 in the TGF-ß1-induced fibrosis model of SV-HUC-1 cells was delineated. RNA-seq, immunofluorescence, immunohistochemistry (IHC), and Western blotting were used to evaluate the degrees of fibrosis and biochemical signaling pathways. Piezo1 protein expression was noticeably elevated in the human NB bladder. The abundance of Piezo1 protein in bladder of NB rats was significantly increased. RNA-seq analysis revealed that the ECM-receptor interaction signaling pathway and collagen-containing ECM were increased in spinal cord injury (SCI)-induced bladder fibrosis. Moreover, the bladder of the NB rat model showed activation of YAP1 and TGF-ß1/Smad. In SV-HUC-1 cells, siRNA suppression of Piezo1 led to profibrotic responses and activation of the TGF-ß1/Smad pathway. However, Yoda1, a Piezo1-specific agonist, significantly reduced these effects. TGF-ß1 increased Piezo1 activation and profibrotic responses in SV-HUC-1 cells. In the TGF-ß1-induced fibrosis model of SV-HUC-1 cells, the TGF-ß1/Smad pathway was activated, whereas the Hippo/YAP1 signal pathway was blocked. Inhibition of Piezo1 further prevented this process. Piezo1 is involved in the progression of NB bladder fibrosis and profibrotic alterations in SV-HUC-1 cells, likely through regulating the TGF-ß1/Smad and Hippo/YAP1 pathways.

Cyclic tensile stress promotes osteogenic differentiation via upregulation of Piezo1 in human dental follicle stem cells.

As periodontal progenitor cells, human dental follicle stem cells (hDFCs) play an important role in regenerative medicine research. Mechanical stimuli exert different regulatory effects on various functions of stem cells. Mechanosensitive ion channels can perceive and transmit mechanical signals. Piezo1 is a novel mechanosensitive cation channel dominated by Ca2+ permeation. The yes-associated protein 1 (YAP1) and mitogen-activated protein kinase (MAPK) pathways can respond to mechanical stimuli and play important roles in cell growth, differentiation, apoptosis, and cell cycle regulation. In this study, we demonstrated that Piezo1 was able to transduce cyclic tension stress (CTS) and promote the osteogenic differentiation of hDFCs by applying CTS of 2000 µstrain to hDFCs. Further investigation of this mechanism revealed that CTS activated Piezo1 in hDFCs and resulted in increased levels of intracellular Ca2+, YAP1 nuclear translocation, and phosphorylated protein expression levels of extracellular signalling-associated kinase 1/2 (ERK 1/2) and Jun amino-terminal kinase 1/2/3 (JNK 1/3) of the MAPK pathway family. However, when Piezo1 was knocked down in the hDFCs, all these increases disappeared. We conclude that CTS activates Piezo1 expression and promotes its osteogenesis via Ca2+/YAP1/MAPK in hDFCs. Appropriate mechanical stimulation promotes the osteogenic differentiation of hDFCs via Piezo1. Targeting Piezo1 may be an effective strategy to regulate the osteogenic differentiation of hDFCs, contributing to MSC-based therapies in the field of bone tissue engineering.

Role of Piezo1 in Terminal Density Reversal of Red Blood Cells.

Density reversal of senescent red blood cells has been known for a long time, yet the identity of the candidate ion transporter(s) causing the senescent cells to swell is still elusive. While performing fractionation of RBCs from healthy individuals in Percoll density gradient and characterization of the separated fractions, we identified a subpopulation of cells in low-density fraction (1.02% ± 0.47) showing signs of senescence such as loss of membrane surface area associated with a reduction in band 3 protein abundance, and Phosphatidylserine (PS) exposure to the outer membrane. In addition, we found that these cells are overloaded with Na+ and Ca2+. Using a combination of blockers and activators of ion pumps and channels, we revealed reduced activity of Plasma membrane Ca2+ ATPase and an increase in Ca2+ and Na+ leaks through ion channels in senescent-like cells. Our data revealed that Ca2+ overload in these cells is a result of reduced PMCA activity and facilitated Ca2+ uptake via a hyperactive Piezo1 channel. However, we could not exclude the contribution of other Ca2+-permeable ion channels in this scenario. In addition, we found, as a universal mechanism, that an increase in intracellular Ca2+ reduced the initially high selectivity of Piezo1 channel for Ca2+ and allowed higher Na+ uptake, Na+ accumulation, and swelling.

Mitigating aging and doxorubicin induced bone loss in mature mice via mechanobiology based treatments.

Aging leads to a reduced anabolic response to mechanical stimuli and a loss of bone mass and structural integrity. Chemotherapy agents such as doxorubicin exacerbate the degeneration of aging skeleton and further subject older cancer patients to a higher fracture risk. To alleviate this clinical problem, we proposed and tested a novel mechanobiology-based therapy. Building upon prior findings that i) Yoda1, the Piezo1 agonist, promoted bone growth in young adult mice and suppressed bone resorption markers in aged mice, and ii) moderate tibial loading protected bone from breast cancer-induced osteolysis, we hypothesized that combined Yoda1 and moderate loading would improve the structural integrity of adult and aged skeletons in vivo and protect bones from deterioration after chemotherapy. We first examined the effects of 4-week Yoda1 (dose 5 mg/kg, 5 times/week) and moderate tibial loading (4.5 N peak load, 4 Hz, 300 cycles for 5 days/week), individually and combined, on mature mice (∼50 weeks of age). Combined Yoda1 and loading was found to mitigate age-associated cortical and trabecular bone loss better than individual interventions. As expected, the non-treated controls experienced an average drop of cortical polar moment of inertia (Ct.pMOI) by -4.3 % over four weeks and the bone deterioration occurred in the majority (64 %) of the samples. Relative to no treatment, loading alone, Yoda1 alone, and combined Yoda1 and loading increased Ct.pMOI by +7.3 %, +9.5 %, +12.0 % and increased the % of samples with positive Ct.pMOI changes by +32 %, +26 %, and +43 %, respectively, suggesting an additive protection of aging-related bone loss for the combined therapy. We further tested if the treatment efficacy was preserved in mature mice following two weeks (six injections) of doxorubicin at the dose of 2.5 or 5 mg/kg. As expected, doxorubicin increased osteocyte apoptosis, altered bone remodeling, and impaired bone structure. However, the effects induced by DOX were too severe to be rescued by Yoda1 and loading, alone or combined, although loading and Yoda1 individually, or combined, increased the number of mice showing positive responsiveness by 0 %, +15 %, and +29 % relative to no intervention after doxorubicin exposure. Overall, this study supported the potentials and challenges of the Yoda1-based strategy in mitigating the detrimental skeletal effects caused by aging and doxorubicin.

The role of mechanosensitive ion channel Piezo1 in knee osteoarthritis inflammation.

Mechanosensitive ion channel Piezo1 is known to mediate a variety of inflammatory pathways and is also involved in the occurrence and development of many orthopedic diseases. Although its role in the inflammatory mechanism of knee osteoarthritis (KOA) has been reported, a systematic explanation is yet to be seen. This article aims to summarize the role of inflammatory responses in the pathogenesis of KOA and elucidate the mechanism by which the Piezo1-mediated inflammatory response contributes to the pathogenesis of KOA, providing a theoretical basis for the prevention and treatment of knee osteoarthritis. The results indicate that in the mechanism leading to knee osteoarthritis, Piezo1 can mediate the inflammatory response through chondrocytes and synovial cells, participating in the pathological progression of KOA. Piezo1 has the potential to become a new target for the prevention and treatment of this disease. Additionally, as pain is one of the most severe manifestations in KOA patients, the inflammatory response mediated by Piezo1, which causes the release of inflammatory mediators and pro-inflammatory factors leading to pain, can be further explored.

Lysis of human erythrocytes due to Piezo1-dependent cytosolic calcium overload as a mechanism of circulatory removal.

Hematopoietic stem cells surrender organelles during differentiation, leaving mature red blood cells (RBC) devoid of transcriptional machinery and mitochondria. The resultant absence of cellular repair capacity limits RBC circulatory longevity, and old cells are removed from circulation. The specific age-dependent alterations required for this apparently targeted removal of RBC, however, remain elusive. Here, we assessed the function of Piezo1, a stretch-activated transmembrane cation channel, within subpopulations of RBC isolated based on physical properties associated with aging. We subsequently investigated the potential role of Piezo1 in RBC removal, using pharmacological and mechanobiological approaches. Dense (old) RBC were separated from whole blood using differential density centrifugation. Tolerance of RBC to mechanical forces within the physiological range was assessed on single-cell and cell population levels. Expression and function of Piezo1 were investigated in separated RBC populations by monitoring accumulation of cytosolic Ca2+ and changes in cell morphology in response to pharmacological Piezo1 stimulation and in response to physical forces. Despite decreased Piezo1 activity with increasing cell age, tolerance to prolonged Piezo1 stimulation declined sharply in older RBC, precipitating lysis. Cell lysis was immediately preceded by an acute reversal of density. We propose a Piezo1-dependent mechanism by which RBC may be removed from circulation: Upon adherence of these RBC to other tissues, they are uniquely exposed to prolonged mechanical forces. The resultant sustained activation of Piezo1 leads to a net influx of Ca2+, overpowering the Ca2+-removal capacity of specifically old RBC, which leads to reversal of ion gradients, dysregulated cell hydration, and ultimately osmotic lysis.

Epithelial Piezo1 deletion ameliorates intestinal barrier damage by regulating ferroptosis in ulcerative colitis.

Ferroptosis, a recently discovered form of regulated cell death, has been implicated in the development of ulcerative colitis (UC). While Piezo1's role in inducing ferroptosis in chondrocytes and pulmonary endothelial cells is documented, its regulatory function in ferroptosis and intestinal epithelial cells in UC remains unclear. To address this, colonic tissue samples from patients with UC were examined, and specific intestinal epithelial Piezo1-deficient (Piezo1ΔIEC) mice were created to investigate Piezo1's role in UC pathogenesis. Elevated epithelial Piezo1 levels were observed in patients with UC, correlating with increased ferroptosis and tight junction (TJ) disruption. In dextran sulfate sodium (DSS)-induced colitis, Piezo1ΔIEC mice exhibited significantly reduced intestinal inflammation and improved gut barrier function compared to wild-type (WT) mice. Moreover, Piezo1 deficiency in colitis mice and lipopolysaccharide (LPS)-stimulated Caco-2 cells led to higher TJ protein levels, reduced lipid peroxidation, enhanced mitochondrial function, and altered expression of ferroptosis-associated proteins. Additionally, erastin, a ferroptosis activator, reversed the protective effect of Piezo1 silencing against LPS-induced ferroptosis in Caco-2 cells. Mechanistically, Piezo1 was found to regulate ferroptosis via the AMPK/mTOR signaling pathway. These findings highlight a novel role for Piezo1 deletion in mitigating ferroptosis in intestinal epithelial cells, suggesting Piezo1 as a potential therapeutic target for UC treatment.

Functional characterization of native Piezo1 as calcium and magnesium influx pathway in human myeloid leukemia cells.

Piezo1 is a Ca2+-permeable mechanically activated ion channel that is involved in various physiological processes and cellular responses to mechanical stimuli. The study of biophysical characteristics of Piezo1 is important for understanding the mechanisms of its function and regulation. Stretch activation, a routine approach that is applied to stimulate Piezo1 activity in the plasma membrane, has a number of significant limitations that complicate precise single-channel analysis. Here, we aimed to determine pore properties of native Piezo1, specifically to examine permeation for physiologically relevant signaling divalent ions (calcium and magnesium) in human myeloid leukemia K562 cells using Piezo1-specific chemical agonist, Yoda1. Using a combination of low-noise single-current patch-clamp recordings of Piezo1 activity in response to Yoda1, we have determined single-channel characteristics of native Piezo1 under various ionic conditions. Whole-cell assay allowed us to directly measure Piezo1 single currents carried by Ca2+ or Mg2+ ions in the absence of other permeable cations in the extracellular solutions; unitary conductance values estimated at various concentrations of Mg2+ revealed strong saturation effect. Patch clamp data complemented with fluorescent imaging clearly evidenced Ca2+ and Mg2+ entry via native Piezo1 channel in human leukemia K562 cells. Mg2+ influx via Piezo1 was detected under quasi-physiological conditions, thus showing that Piezo1 channels could potentially provide the physiological relevant pathway for Mg2+ ion transport and contribute to the regulation of Mg2+-dependent intracellular signaling.

Activation of Piezo1 or TRPV2 channels inhibits human ureteral contractions via NO release from the mucosa.

We aimed to investigate the expression and motor modulatory roles of several mechano-sensitive channels (MSCs) in human ureter. Human proximal ureters were obtained from eighty patients subjected to nephrectomy. Expression of MSCs at mRNA, protein and functional levels were examined. Contractions of longitudinal ureter strips were recorded in organ bath. A fluorescent probe Diaminofluoresceins was used to measure nitric oxide (NO). RT-PCR analyses revealed predominant expression of Piezo1 and TRPV2 mRNA in intact ureter and mucosa. Immunofluorescence assays indicate proteins of MSCs (Piezo1/Piezo2, TRPV2 and TRPV4) were mainly distributed in the urothelium. Ca2+ imaging confirmed functional expression of TRPV2, TRPV4 and Piezo1 in cultured urothelial cells. Specific agonists of Piezo1 (Yoda1, 3-300 µM) and TRPV2 (cannabidiol, 3-300 µM) attenuated the frequency of ureteral contractions in a dose-dependent manner while the TRPV4 agonist GSK1016790A (100 nM-1 µM) exerted no effect. The inhibitory effects of Piezo1 and TRPV2 agonists were significantly blocked by the selective antagonists (Dooku 1 for Piezo1, Tranilast for TRPV2), removal of the mucosa, and pretreatment with NO synthase inhibitor L-NAME (10 µM). Yoda1 (30 µM) and cannabidiol (50 µM) increased production of NO in cultured urothelial cells. Our results suggest that activation of Piezo1 or TRPV2 evokes NO production and release from mucosa that may mediate mechanical stimulus-induced reduction of ureter contractions. Our findings support the idea that targeting Piezo1 and TRPV2 channels may be a promising pharmacological strategy for ureter stone passage or colic pain relief.

The emerging role of Piezo1 in the musculoskeletal system and disease.

Piezo1, a mechanosensitive ion channel, has emerged as a key player in translating mechanical stimuli into biological signaling. Its involvement extends beyond physiological and pathological processes such as lymphatic vessel development, axon growth, vascular development, immunoregulation, and blood pressure regulation. The musculoskeletal system, responsible for structural support, movement, and homeostasis, has recently attracted attention regarding the significance of Piezo1. This review aims to provide a comprehensive summary of the current research on Piezo1 in the musculoskeletal system, highlighting its impact on bone formation, myogenesis, chondrogenesis, intervertebral disc homeostasis, tendon matrix cross-linking, and physical activity. Additionally, we explore the potential of targeting Piezo1 as a therapeutic approach for musculoskeletal disorders, including osteoporosis, muscle atrophy, intervertebral disc degeneration, and osteoarthritis.