Stretch-activated ion channel Piezo1 directs lineage choice in human neural stem cells

TRIM25 facilitates ferroptosis in ovarian cancer through promoting PIEZO1 K63-linked ubiquitination and degradation

BACKGROUND

Ovarian cancer represents a significant threat to women's health. and ferroptosis is recognized as a potential natural inhibitor in cancer therapy, the regulatory mechanism of TRIM25 in ovarian cancer and its potential for regulating ferroptosis as a treatment remain unclear.

METHODS

The role of TRIM25 in ovarian cancer was examined through functional gain- and loss-of-function assays both in vitro and in vivo, while its target genes were identified. The stability and ubiquitination sites of PIEZO1 were analyzed using protein docking and ubiquitination experiments.

RESULTS

TRIM25 is highly expressed in ovarian cancer and promotes the growth and metastasis of ovarian cancer cells both in vivo and in vitro. Mechanistically, it facilitates PIEZO1 degradation through ubiquitination-dependent proteasome activity, inhibits ferroptosis, and stimulates ovarian cancer cell growth.

CONCLUSION

Our study clearly shows that TRIM25 stimulates ovarian cancer by inducing K63-linked ubiquitination of PIEZO1, which suppresses ferroptosis and promotes excessive proliferation of ovarian cancer cells. Further research identified the ubiquitination modification site on PIEZO1, providing insights for ovarian cancer treatment.

Opposing Calcium-Dependent Effects of GsMTx4 in Acute Lymphoblastic Leukemia: In Vitro Proliferation vs. In Vivo Survival Advantage

Mechanogated (MG) ion channels play a crucial role in mechano-transduction and immune cell regulation, yet their impact on blood cancers, particularly acute lymphoblastic leukemia (ALL), remains poorly understood. This study investigates the pharmacological effects of GsMTx4, an MG channel inhibitor, in human ALL cells both in vitro and in vivo. Unexpectedly, we found that GsMTx4 remarkably increased basal calcium (Ca2+) levels in ALL cells through constitutive Ca2+ entry and enhanced store-operated Ca2⁺ influx upon thapsigargin stimulation. This increase in basal Ca2+ signaling promoted ALL cell viability and proliferation in vitro. Notably, chelating intracellular Ca2+ with BAPTA-AM reduces GsMTx4-mediated leukemia cell viability and proliferation. However, in vivo, GsMTx4 decreases cytosolic Ca2+ levels in Nalm-6 GFP⁺ cells isolated from mouse blood, effectively countering leukemia progression and significantly extending survival in NSG mice transplanted with leukemia cells (median survival: GsMTx4 vs. control, 37.5 days vs. 29 days, p = 0.0414). Our results highlight the different properties of GsMTx4 activity in in vitro and in vivo models. They also emphasize that Ca2+ signaling is a key vulnerability in leukemia, where its precise modulation dictates disease progression. Thus, targeting Ca2+ channels could offer a novel therapeutic strategy for leukemia by exploiting Ca2+ homeostasis.

Mechanosensitive ion channel Piezo1 modulates the response of rat hippocampus neural stem cells to rapid stretch injury

Traumatic brain injury (TBI) is one of the primary causes of long-term brain disabilities among military personnel and civilians, regardless of gender. A plethora of secondary events are triggered by a primary brain insult, increasing the complexity of TBI. One of the most affected brain regions is the hippocampus, where neurogenesis occurs throughout life due to the presence of neural stem cells (NSC). Preclinical models have been extensively used to better understand TBI and develop effective treatments. Among these, rapid stretch injury has been used to mimic the effect of mechanical stress produced by a TBI on neurons and glia in vitro. In this study, we aimed to determine the impact of rapid stretch on the viability, proliferation, and differentiation of NSC isolated from rat hippocampus (Hipp-NSC) and to determine the role of the stretch-activated ion channel Piezo-1 in modulating their response to mechanical stress. We found that while rapid stretch (30 and 50 PSI) reduced Hipp-NSC viability (measured as a function of LDH release), it did not change their proliferation and differentiation potentials. Interestingly, rapid stretch in the presence of a selective Piezo-1 inhibitor, GsMTx4, or Piezo1 targeting siRNA, directed Hipp-NSC differentiation toward a neurogenic lineage. Additionally, we found that inhibiting Piezo1 with the addition of a rapid stretch injury increased the expression of miRNAs known to regulate neurogenesis. This work uses a novel approach for studying the effect of mechanical stress on NSC in vitro and points to the critical role the stretch-activated ion channel Piezo-1 has in modulating the impact of TBI on hippocampal neurogenesis.

Tuina promotes nerve myelin regeneration in SNI rats through Piezo1/YAP/TAZ pathway

PURPOSE

The changes in the mechanical environment of local nerves after peripheral nerve injury (PNI) can cause a series of mechanical electrochemical signal reactions that affect the process of nerve regeneration and functional recovery. Piezo1/YAP/TAZ is an important transduction pathway that affects myelin regeneration. Our previous studies showed that Tuina could treat PNI in a variety of ways, including promoting nerve repair. However, whether Tuina as a kind of benign mechanical stimulation could promote nerve repair by changing the neuromechanical environment and causing changes in the mechanical electrochemical signal transduction pathway Piezo1/YAP/TAZ is unknown.

METHODS

The rats were divided into 4 groups, Sham group, sciatic nerve injury (SNI) group, Tuina group and Tuina + GsMTx4 group, with 6 rats in each group. We established an SNI model. Sciatic nerves at the mid-thigh level were exposed and crushed using a pair of non-serrated forceps for 5 s and the damage points about 2 mm. We used a Tuina manipulation emulator designed by our team to intervent. According to the "Three-Manipulation and Three-Acupoint": the emulator was used to perform the Dian, Bo, and Rou methods on Yinmen (BL37), Chengshan (BL57) and Yanglingquan (GB34) sequentially on the affected side. Each Tuina method was applied for 1 min on each acupoint respectively. Tuina treatment was administered once daily for 20 days. And we observed Somatic Functional Index (SFI), Mechanical Withdrawal Threshold (MWT), electrophysiological test and Shear wave elastography (SWE) examination in each group. Toluidine blue staining was performed to observe nerve fibers. The expression of Piezo1, Yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), Myelin basic protein (MBP), Neurofilament 200 (NF200), S100 calcium-binding protein β(S100β) and Ca2+ were detected using Immunofluorescence (IF), Western Blot (WB), Real-Time Quantitative PCR (RT-PCR) and Calcium Assay Kit.

RESULTS

Tuina improved the SFI, MWT, and compound action potential (CMAP) changes after SNI. The SWE results showed that Tuina reduced Emax and Smax. Piezo1, Ca2+ expression were reduced, YAP, TAZ, MBP, NF200, S100β expression were enhanced by Tuina.

CONCLUSION

The activation of Schwann cells (SCs) and the regeneration of injured nerve myelin post-Tuina intervention are associated with alterations in the Piezo1/YAP/TAZ signaling pathway within SCs, induced by the mechanical forces generated through Tuina.

Smooth muscle cell Piezo1 is essential for phenotypic switch and neointimal hyperplasia

BACKGROUND AND PURPOSE

Disturbed blood flow is a critical factor in activation of vascular smooth muscle cells (VSMCs) and initiation of neointimal hyperplasia. The Piezo1 channel is a recent yet well-characterised mechanosensor that plays a vital role in vascular development and homeostasis. However, the role of VSMC Piezo1 in neointima development remains largely unknown. The purpose of this study is to investigate the functional role of Piezo1 channel in neointimal hyperplasia.

EXPERIMENTAL APPROACH

We measured the expression of Piezo1 in VSMC-rich neointima from human coronary artery samples and two mouse neointimal hyperplasia models which were induced by cast implantation or guidewire injury. We utilised VSMC-specific Piezo1 knockout mice to explore its function and the underlying mechanism of neointimal hyperplasia, both in vivo and in vitro.

KEY RESULTS

In human and mouse neointima samples, we observed a significant up-regulation of Piezo1 expression in the VSMC-rich neointima compared to the medial layer. VSMC-specific knockout of Piezo1 significantly reduced neointimal hyperplasia in both animal models. Activation of Piezo1 facilitates, whereas Piezo1 deficiency inhibits disturbed flow-induced cell proliferation, migration and synthetic phenotype switch. Mechanistic studies suggest that Piezo1 activates YAP and TAZ through Ca2+ and its downstream effectors calmodulin kinase II and calcineurin, which in turn drive VSMC proliferation and migration, thereby facilitating neointimal hyperplasia.

CONCLUSIONS AND IMPLICATIONS

These findings demonstrate a critical role of mechanosensitive Piezo1 channel in neointimal hyperplasia via modulating VSMC phenotype. Piezo1 channels may represent a novel therapeutic target for maladaptive vascular remodelling and occlusive vascular diseases.

Pancreatic stellate cell: Update on molecular investigations and clinical translation in pancreatic cancer

Pancreatic cancer is a particularly aggressive tumor, distinguished by the presence of a prominent collagenous stroma and desmoplasia that envelops the tumor cells. Pancreatic stellate cell (PSC) contributes to the formation of a dense fibrotic stroma and has been demonstrated to facilitate tumor progression. As the significance of PSCs is increasingly revealed, more explorations are focused on the complex molecular mechanisms and tumor-stromal crosstalk in order to guide potential therapeutic approaches through deactivating or reprogramming PSCs. Nevertheless, significant challenges persist in translating preclinical discoveries into clinical applications. In this review, we expect to offer a comprehensive overview of the latest molecular advancements in PSCs, along with new insights into the clinical therapeutic strategies targeting PSCs.

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.

Mechanical cues rewire lipid metabolism and support chemoresistance in epithelial ovarian cancer cell lines OVCAR3 and SKOV3

Epithelial ovarian cancer (EOC) is one of the deadliest cancers in women, and acquired chemoresistance is a major contributor of aggressive phenotypes. Overcoming treatment failure and disease recurrence is therefore an ambitious goal. Ovarian cancer develops in a biophysically challenging environment where the cells are constantly exposed to mechanical deformation originating in the abdomen and shear stress caused by the accumulation of ascitic fluid in the peritoneal cavity. Therefore, mechanical stimulation can be seen as an inseparable part of the tumor microenvironment. The role of biomechanics in shaping tumor metabolism is emerging and promises to be a real game changer in the field of cancer biology. Focusing on two different epithelial ovarian cancer cell lines (SKOV3 and OVCAR3), we explored the impact of shear stress on cellular behavior driven by mechanosensitive transcription factors (TFs). Here, we report data linking physical triggers to the alteration of lipid metabolism, ultimately supporting increased chemoresistance. Mechanistically, shear stress induced adaptation of cell membrane and actin cytoskeleton which were accompanied by the regulation of nuclear translocation of SREBP2 and YAP1. This was associated with increased cholesterol uptake/biosynthesis and decreased sensitivity to the ruthenium-based anticancer drug BOLD-100. Overall, the present study contributes to shedding light on the molecular pathways connecting mechanical cues, tumor metabolism and drug responsiveness.

Mechanotransduction in Development: A Focus on Angiogenesis

Cells respond to external mechanical cues and transduce these forces into biological signals. This process is known as mechanotransduction and requires a group of proteins called mechanosensors. This peculiar class of receptors include extracellular matrix proteins, plasma membrane proteins, the cytoskeleton and the nuclear envelope. These cell components are responsive to a wide spectrum of physical cues including stiffness, tensile force, hydrostatic pressure and shear stress. Among mechanotransducers, the Transient Receptor Potential (TRP) and the PIEZO family members are mechanosensitive ion channels, coupling force transduction with intracellular cation transport. Their activity contributes to embryo development, tissue remodeling and repair, and cell homeostasis. In particular, vessel development is driven by hemodynamic cues such as flow direction and shear stress. Perturbed mechanotransduction is involved in several pathological vascular phenotypes including hereditary hemorrhagic telangiectasia. This review is conceived to summarize the most recent findings of mechanotransduction in development. We first collected main features of mechanosensitive proteins. However, we focused on the role of mechanical cues during development. Mechanosensitive ion channels and their function in vascular development are also discussed, with a focus on brain vessel morphogenesis.

PIEZO1 Drives Trophoblast Fusion and Placental Development

PIEZO1, a mechanosensor1,2 in endothelial cells, plays a critical role in fetal vascular development during embryogenesis3,4. However, its expression and function in placental trophoblasts remain unexplored. Here, we demonstrate that PIEZO1 is expressed in placental villus trophoblasts, where it is essential for trophoblast fusion and placental development. Mice with trophoblast-specific PIEZO1 knockout exhibit embryonic lethality without obvious vascular defects. Instead, PIEZO1 deficiency disrupts the formation of the syncytiotrophoblast layer in the placenta. Mechanistically, PIEZO1-mediated calcium influx activates TMEM16F lipid scramblase, facilitating the externalization of phosphatidylserine, a key "fuse-me" signal for trophoblast fusion5,6. These findings reveal PIEZO1 as a crucial mechanosensor in trophoblasts and highlight its indispensable role in trophoblast fusion and placental development, expanding our understanding of PIEZO1's functions beyond endothelial cells during pregnancy.

The mechanosensitive channel ELKIN1 regulates cellular adaptations to simulated microgravity

In conditions of microgravity the human body undergoes extensive alterations in physiological function. However, it has proven challenging to determine how these changes are mediated at the molecular and cellular level. Here, we investigated whether ELKIN1, a mechanically activated ion channel, regulates changes in cellular and molecular structures in conditions of simulated microgravity. Deletion of ELKIN1 inhibited the simulated microgravity-induced alterations of cellular structure and attachment. In addition, cells lacking ELKIN1 did not exhibit changes in focal adhesion structures and redistribution of the YAP1 transcription factor in response to simulated microgravity, consistent with wild type cells. Finally, melanoma cell invasion of a collagen gel, from organotypic spheroids, was reduced in simulated microgravity, in an ELKIN1 dependent manner. Thus, the force sensing molecule, ELKIN1, modulates the impact of microgravity at both the molecular and cellular levels, revealing one of the molecular mechanisms that underpins cellular adaptations to conditions of microgravity.

Piezo1 Ion Channels Regulate the Formation and Spreading of Human Endometrial Mesenchymal Stem Cell Spheroids

Mesenchymal stem cells obtained from desquamated endometrium (eMSCs) are considered as reliable and promising objects for stem cell-based therapy. eMSCs aggregated into three-dimensional (3D) spheroids demonstrate greater efficiency compared to monolayer 2D eMSCs. However, molecular processes and specific mechanisms regulating the effectiveness of spheroids remain unknown. Regulation of a number of physiological reactions in MSCs is associated with the functioning of Ca2+-permeable mechanosensitive Piezo1 channels. In our previous study, we showed that selective Piezo1 activation by its selective agonist Yoda1 controls the migratory activity of 2D eMSCs. Here, we aimed to determine the effect of Yoda1 on eMSC spheroid formation and spreading. PIEZO1 mRNA expression was lower in spheroids compared to 2D culture. Spheroids formed with Yoda1 or spread in the presence of Yoda1 demonstrated lower spreading rates compared to control (Yoda1-free) spheroids. The spreading rates of control spheroids depended on the substrate stiffness, whereas spheroids formed with Yoda1 had similar spreading rates regardless of the surface properties. Our results demonstrate several Piezo1-dependent reactions of eMSC spheroids that could be modulated by selective Piezo1 activation.

Actin-based deformations of the nucleus control mouse multiciliated ependymal cell differentiation

Ependymal cells (ECs) are multiciliated cells in the brain that contribute to cerebrospinal fluid flow. ECs are specified during embryonic stages but differentiate later in development. Their differentiation depends on genes such as GEMC1 and MCIDAS in conjunction with E2F4/5 as well as on cell-cycle-related factors. In the mouse brain, we observe that nuclear deformation accompanies EC differentiation. Tampering with these deformations either by decreasing F-actin levels or by severing the link between the nucleus and the actin cytoskeleton blocks differentiation. Conversely, increasing F-actin by knocking out the Arp2/3 complex inhibitor Arpin or artificially deforming the nucleus activates differentiation. These data are consistent with actin polymerization triggering nuclear deformation and jump starting the signaling that produces ECs. A player in this process is the retinoblastoma 1 (RB1) protein, whose phosphorylation prompts MCIDAS activation. Overall, this study identifies a role for actin-based mechanical inputs to the nucleus as controlling factors in cell differentiation.

Piezo1 promotes intervertebral disc degeneration through the Ca2+/F-actin/Yap signaling axis

BACKGROUND

Piezo1 is a mechanically sensitive cation channel expressed in various tissues of the human body and has multiple roles in both physiological and pathological processes. However, its role in the occurrence and development of intervertebral disc degeneration (IVDD) is not fully understood.

METHODS

In the present study, an IVDD mouse model and Piezo1 small interfering (si)RNA was used to investigate the role of Piezo1 in IVDD progression. Furthermore, the Ca2+ inhibitor, BAPTA-AM, and the F-actin cytoskeleton polymerization inhibitor, Latrunculin A, were employed to examine the roles of Ca2+ influx and cytoskeleton dynamics in Piezo1-mediated IVDD progression. Additionally, Yes-associated protein (Yap) small interfering (si)RNA was used to investigate the involvement of Yap in Piezo1-induced IVDD progression.

RESULTS

The findings of the present study indicated that Piezo1 was positively associated with IVDD and that Piezo1 upregulation promoted IVDD via facilitating cartilage endplate (CEP) degeneration and calcification. The Ca2+ inhibitor, BAPTA-AM, and the F-actin cytoskeleton polymerization inhibitor, Latrunculin A, inhibited Piezo1-mediated extracellular matrix degradation and CEP chondrocyte degeneration. Moreover, it was found that Piezo1 activated Yap through an F-actin-mediated non-canonical pathway and that Yap siRNA inhibited Piezo1 upregulation-induced IVDD progression.

CONCLUSION

Overall, the results of the present study indicate that increased expression of Piezo1 is closely related to the occurrence and development of IVDD and that the Piezo1-mediated Ca2+/F-actin/Yap axis contributes to this process. Thus, targeting Piezo1 may provide a new strategy for the treatment of IVDD.

Substrate stiffness modulates osteogenic and adipogenic differentiation of osteosarcoma through PIEZO1 mediated signaling pathway

Most osteosarcoma (OS) cases exhibit poor differentiation at the histopathological level. Disruption of the normal osteogenic differentiation process results in the unregulated proliferation of precursor cells, which is a critical factor in the development of OS. Differentiation therapy aims to slow disease progression by restoring the osteogenic differentiation process of OS cells and is considered a new approach to treating OS. However, there are currently few studies on the mechanism of differentiation of OS, which puts the development of differentiation therapeutic drugs into a bottleneck. Substrate stiffness can regulate differentiation in mesenchymal stem cells. Evidence supports that mesenchymal stem cells and osteoblast precursors are the origin of OS. In this study, we simulated different stiffnesses in vitro to investigate the mechanism of substrate stiffness affecting differentiation of OS. We demonstrate that Piezo type mechanosensitive ion channel component 1 (PIEZO1) plays a critical regulatory role in sensing substrate stiffness in osteogenic and adipogenic differentiation of OS. When OS cells are cultured on the stiff substrate, integrin subunit beta 1 (ITGB1) increases and cooperates with PIEZO1 to promote Yes-Associated Protein (YAP) entering the nucleus, and may inhibit EZH2, thereby inhibiting H3K27me3 and increasing RUNX2 expression, and cells differentiate toward osteogenesis. Our results provide new insights for research on differentiation treatment of OS and are expected to help identify new targets for future drug design.

PIEZO channels as multimodal mechanotransducers

All living beings experience a wide range of endogenous and exogenous mechanical forces. The ability to detect these forces and rapidly convert them into specific biological signals is essential to a wide range of physiological processes. In vertebrates, these fundamental tasks are predominantly achieved by two related mechanosensitive ion channels called PIEZO1 and PIEZO2. PIEZO channels are thought to sense mechanical forces through flexible transmembrane blade-like domains. Structural studies indeed show that these mechanosensory domains adopt a curved conformation in a resting membrane but become flattened in a membrane under tension, promoting an open state. Yet, recent studies suggest the intriguing possibility that distinct mechanical stimuli activate PIEZO channels through discrete molecular rearrangements of these domains. In addition, biological signals downstream of PIEZO channel activation vary as a function of the mechanical stimulus and of the cellular context. These unique features could explain how PIEZOs confer cells the ability to differentially interpret a complex landscape of mechanical cues.

In vitro stretch modulates mitochondrial dynamics and energy metabolism to induce smooth muscle differentiation in mesenchymal stem cells

The smooth muscle cells (SMCs) located in the vascular media layer are continuously subjected to cyclic stretching perpendicular to the vessel wall and play a crucial role in vascular wall remodeling and blood pressure regulation. Mesenchymal stem cells (MSCs) are promising tools to differentiate into SMCs. Mechanical stretch loading offers an opportunity to guide the MSC-SMC differentiation and mechanical adaption for function regeneration of blood vessels. This study shows that cyclic stretch induces the expression of SMC markers α-SMA and SM22 in MSCs. These cells exhibit contractile ability in vitro and facilitate angiogenesis in the Matrigel plug assay in vivo. The contraction of SMCs requires remodeling of their energy metabolism. However, the underlying mechanism in the differentiation of MSCs into SMCs remains to be revealed. Cyclic stretch training promotes glycolysis, oxidative phosphorylation, and mitochondrial fusion and modulates mitochondrial dynamics-related proteins (MFN1, MFN2, DRP1) expression, thereby contributing to MSCs differentiation. Yes-associated protein (YAP) affects mitochondrial dynamics, oxidative phosphorylation, and glycolysis to regulate stretch-mediated differentiation into SMCs. Additionally, Piezo-type mechanosensitive ion channel component 1 (Piezo1) impacts energy metabolism and MSCs differentiation by regulating intracellular Ca2+ levels and YAP nuclear localization. It indicates that YAP can integrate stretch force and energy metabolism signals to regulate the differentiation of MSCs into SMCs.

Motile cilia modulate neuronal and astroglial activity in the zebrafish larval brain

The brain uses a specialized system to transport cerebrospinal fluid (CSF), consisting of interconnected ventricles lined by motile ciliated ependymal cells. These cells act jointly with CSF secretion and cardiac pressure gradients to regulate CSF dynamics. To date, the link between cilia-mediated CSF flow and brain function is poorly understood. Using zebrafish larvae as a model system, we identify that loss of ciliary motility does not alter progenitor proliferation, brain morphology, or spontaneous neural activity despite leading to an enlarged telencephalic ventricle. We observe altered neuronal responses to photic stimulations in the optic tectum and hindbrain and brain asymmetry defects in the habenula. Finally, we investigate astroglia since they contact CSF and regulate neuronal activity. Our analyses reveal a reduction in astroglial calcium signals during both spontaneous and light-evoked activity. Our findings highlight a role of motile cilia in regulating brain physiology through the modulation of neural and astroglial networks.

Mechanical force receptor Piezo1 regulates TH9 cell differentiation

Interleukin (IL)-9-producing CD4+ T cells (TH9) are essential for mediating antitumor immunity, but the mechanisms of TH9 cell differentiation remain unclear. Here, we found that the mechanical force receptor Piezo1 is critical for regulating TH9 cell differentiation. Piezo1 deficiency in CD4+ T cells intrinsically inhibited TH9 cell differentiation, whereas ectopic Piezo1 expression promoted this process. Notably, Piezo1 deficiency inhibited TH9 cell differentiation and contributed to tumor development. Mechanistically, Piezo1 deficiency inhibits TH9 cell differentiation mainly through the SIRT3-succinate dehydrogenase A (SDHA)-oxidative phosphorylation (OXPHOS) pathway. SIRT3 deficiency or blockade of SDHA-OXPHOS signaling activity reversed the TH9 cell differentiation induced by Piezo1 deficiency. Moreover, HIF1α signaling is responsible for the TH9 cell differentiation induced by Piezo1 deficiency. Thus, our findings identify a redox metabolism signaling mechanism regulated by the mechanical force receptor Piezo1 that limits the mitochondrial SIRT3-SDHA-dependent OXPHOS pathway and triggers HIF1α-IL-9 to reprogram TH9 cell differentiation, with implications for future immunotherapy approaches.

Visualizing PIEZO1 Localization and Activity in hiPSC-Derived Single Cells and Organoids with HaloTag Technology

PIEZO1 is critical to numerous physiological processes, transducing diverse mechanical stimuli into electrical and chemical signals. Recent studies underscore the importance of visualizing endogenous PIEZO1 activity and localization to understand its functional roles. To enable physiologically and clinically relevant studies on human PIEZO1, we genetically engineered human induced pluripotent stem cells (hiPSCs) to express a HaloTag fused to endogenous PIEZO1. Combined with advanced imaging, our chemogenetic platform allows precise visualization of PIEZO1 localization dynamics in various cell types. Furthermore, the PIEZO1-HaloTag hiPSC technology facilitates the non-invasive monitoring of channel activity across diverse cell types using Ca2+-sensitive HaloTag ligands, achieving temporal resolution approaching that of patch clamp electrophysiology. Finally, we used lightsheet imaging of hiPSC-derived neural organoids to achieve molecular scale imaging of PIEZO1 in three-dimensional tissue organoids. Our advances offer a novel platform for studying PIEZO1 mechanotransduction in human cells and tissues, with potential for elucidating disease mechanisms and targeted therapeutic development.

PIEZO1-mediated mechanotransduction regulates collagen synthesis on nanostructured 2D and 3D models of fibrosis

Progressive fibrosis can lead to tissue malfunction and organ failure due to the pathologic accumulation of a collagen-rich extracellular matrix. In vitro models provide useful tools for deconstructing the roles of specific biomechanical or biological mechanisms, such as substrate micro- and nanoscale architecture, in these processes for identifying potential therapeutic targets. Here, we investigated how the mechanosensitive ion channel PIEZO1 influences fibrotic gene and protein expression in adipose-derived stem cells (hASCs). Specifically, we examined the role of PIEZO1 and the mechanosensitive transcription factors YAP/TAZ in sensing aligned or non-aligned substrate architecture to regulate collagen formation. We utilized both 2D microphotopatterned substrates and 3D electrospun polycaprolactone (PCL) substrates to study the role of culture dimensionality. We found that PIEZO1 regulates collagen synthesis in hASCs in a manner that is sensitive to substrate architecture. Activation of PIEZO1 induced significant morphological changes in hASCs, particularly when cultured on aligned substrates, leading to a 30-40 % reduction in cell spreading area and increased cell elongation, in 3D-aligned cultures. Picrosirius Red staining and immunoblotting revealed that PIEZO1 activation reduced collagen accumulation in 3D culture. While YAP translocated to the cytoplasm following PIEZO1 activation, depleting YAP and TAZ did not change collagen expression significantly downstream of PIEZO1 activation, implying that YAP/TAZ translocation from the nucleus and decreased collagen synthesis may be independent consequences of PIEZO1 activation. Our studies demonstrate a role for PIEZO1 in cellular mechanosensing of substrate architecture and provide targetable pathways for treating fibrosis and for enhancing tissue-engineered and regenerative approaches for fibrous tissue repair. STATEMENT OF SIGNIFICANCE: This study examines how cells sense and respond to their physical environment via PIEZO1 mechanotransduction. We discovered that cells use PIEZO1 to detect the alignment of surrounding structures, influencing the production of collagen - a key component in fibrosis. Our study used both 2D and 3D models to mimic different tissue environments, providing new insights into how cellular responses change in more complex settings. Importantly, we found that activating PIEZO1 alters cell shape and collagen production, especially on aligned surfaces. Interestingly, while PIEZO1 activation caused YAP translocation to the cytoplasm, this translocation did not directly affect collagen production. This work advances our understanding of fibrosis development and identifies PIEZO1 as a potential target for new therapies.

Deciphering mechanical cues in the microenvironment: from non-malignant settings to tumor progression

The tumor microenvironment functions as a dynamic and intricate ecosystem, comprising a diverse array of cellular and non-cellular components that precisely orchestrate pivotal tumor behaviors, including invasion, metastasis, and drug resistance. While unraveling the intricate interplay between the tumor microenvironment and tumor behaviors represents a tremendous challenge, recent research illuminates a crucial biological phenomenon known as cellular mechanotransduction. Within the microenvironment, mechanical cues like tensile stress, shear stress, and stiffness play a pivotal role by activating mechanosensitive effectors such as PIEZO proteins, integrins, and Yes-associated protein. This activation initiates cascades of intrinsic signaling pathways, effectively linking the physical properties of tissues to their physiological and pathophysiological processes like morphogenesis, regeneration, and immunity. This mechanistic insight offers a novel perspective on how the mechanical cues within the tumor microenvironment impact tumor behaviors. While the intricacies of the mechanical tumor microenvironment are yet to be fully elucidated, it exhibits distinct physical attributes from non-malignant tissues, including elevated solid stresses, interstitial hypertension, augmented matrix stiffness, and enhanced viscoelasticity. These traits exert notable influences on tumor progression and treatment responses, enriching our comprehension of the multifaceted nature of the microenvironment. Through this innovative review, we aim to provide a new lens to decipher the mechanical attributes within the tumor microenvironment from non-malignant contexts, broadening our knowledge on how these factors promote or inhibit tumor behaviors, and thus offering valuable insights to identify potential targets for anti-tumor strategies.

Single-particle tracking reveals heterogeneous PIEZO1 diffusion

The mechanically activated ion channel PIEZO1 is critical to numerous physiological processes, and is activated by diverse mechanical cues. The channel is gated by membrane tension and has been found to be mobile in the plasma membrane. We employed single-particle tracking (SPT) of endogenous, tdTomato-tagged PIEZO1 using total internal reflection fluorescence microscopy in live cells. Application of SPT unveiled a surprising heterogeneity of diffusing PIEZO1 subpopulations, which we labeled "mobile" and "immobile." We sorted these trajectories into the two aforementioned categories using trajectory spread. To evaluate the effects of the plasma membrane composition on PIEZO1 diffusion, we manipulated membrane composition by depleting or supplementing cholesterol, or by adding margaric acid to stiffen the membrane. To examine effects of channel activation on PIEZO1 mobility, we treated cells with Yoda1, a PIEZO1 agonist, and GsMTx-4, a channel inhibitor. We collected thousands of trajectories for each condition, and found that cholesterol removal and Yoda1 incubation increased the channel's propensity for mobility. Conversely, we found that GsMTx-4 incubation and cholesterol supplementation resulted in a lower chance of mobile trajectories, whereas margaric acid incubation did not have a significant effect on PIEZO1 mobility. The mobile trajectories were analyzed further by fitting the time-averaged mean-squared displacement as a function of lag time to a power law model, revealing that mobile PIEZO1 puncta exhibit anomalous subdiffusion. These studies illuminate the fundamental properties governing PIEZO1 diffusion in the plasma membrane and set the stage to determine how cellular processes and interactions may influence channel activity and mobility.

The mechanisms of exercise improving cardiovascular function by stimulating Piezo1 and TRP ion channels: a systemic review

Mechanosensitive ion channels are widely distributed in the heart, lung, bladder and other tissues, and plays an important role in exercise-induced cardiovascular function promotion. By reviewing the PubMed databases, the results were summarized using the terms "Exercise/Sport", "Piezo1", "Transient receptor potential (TRP)" and "Cardiovascular" as the keywords, 124-related papers screened were sorted and reviewed. The results showed that: (1) Piezo1 and TRP channels play an important role in regulating blood pressure and the development of cardiovascular diseases such as atherosclerosis, myocardial infarction, and cardiac fibrosis; (2) Exercise promotes cardiac health, inhibits the development of pathological heart to heart failure, regulating the changes in the characterization of Piezo1 and TRP channels; (3) Piezo1 activates downstream signaling pathways with very broad pathways, such as AKT/eNOS, NF-κB, p38MAPK and HIPPO-YAP signaling pathways. Piezo1 and Irisin regulate nuclear localization of YAP and are hypothesized to act synergistically to regulate tissue mechanical properties of the cardiovascular system and (4) The cardioprotective effects of exercise through the TRP family are mostly accomplished through Ca2+ and involve many signaling pathways. TRP channels exert their important cardioprotective effects by reducing the TRPC3-Nox2 complex and mediating Irisin-induced Ca2+ influx through TRPV4. It is proposed that exercise stimulates the mechanosensitive cation channel Piezo1 and TRP channels, which exerts cardioprotective effects. The activation of Piezo1 and TRP channels and their downstream targets to exert cardioprotective function by exercise may provide a theoretical basis for the prevention of cardiovascular diseases and the rehabilitation of clinical patients.

Characterization of Mesenchymal and Neural Stem Cells Response to Bipolar Microsecond Electric Pulses Stimulation

In the tissue regeneration field, stem cell transplantation represents a promising therapeutic strategy. To favor their implantation, proliferation and differentiation need to be controlled. Several studies have demonstrated that stem cell fate can be controlled by applying continuous electric field stimulation. This study aims to characterize the effect of a specific microsecond electric pulse stimulation (bipolar pulses of 100 µs + 100 µs, delivered for 30 min at an intensity of 250 V/cm) to induce an increase in cell proliferation on mesenchymal stem cells (MSCs) and induced neural stem cells (iNSCs). The effect was evaluated in terms of (i) cell counting, (ii) cell cycle, (iii) gene expression, and (iv) apoptosis. The results show that 24 h after the stimulation, cell proliferation, cell cycle, and apoptosis are not affected, but variation in the expression of specific genes involved in these processes is observed. These results led us to investigate cell proliferation until 72 h from the stimulation, observing an increase in the iNSCs number at this time point. The main outcome of this study is that the microsecond electric pulses can modulate stem cell proliferation.

Physical modulation and peripheral nerve regeneration: a literature review

Peripheral nerve injury (PNI) usually causes severe motor, sensory and autonomic dysfunction. In addition to direct surgical repair, rehabilitation exercises, and traditional physical stimuli, for example, electrical stimulation, have been applied in promoting the clinical recovery of PNI for a long time but showed low efficiency. Recently, significant progress has been made in new physical modulation to promote peripheral nerve regeneration. We hereby review current progress on the mechanism of peripheral nerve regeneration after injury and summarize the new findings and evidence for the application of physical modulation, including electrical stimulation, light, ultrasound, magnetic stimulation, and mechanical stretching in experimental studies and the clinical treatment of patients with PNI.

The Role of Mechanosensitive Piezo Channels in Chronic Pain

Purpose of Review

Mechanosensitive Piezo channels are ion channels activated by mechanical stimuli, playing a crucial role in mechanotransduction processes and mechanical hypersensitivity. When these channels are subjected to mechanical loading, membrane currents rise instantaneously, depolarizing and activating voltage-gated calcium channels. This results in an increase in intracellular Ca2+, which contributes to heightened sensitivity to mechanical stimuli. This review delves into the characteristics and mechanisms of Piezo channels in chronic pain.

Recent Findings

The findings suggest that Piezo channels are integral to the occurrence and development of chronic pain, including neuropathic pain, visceral pain, musculoskeletal pain, headache or orofacial pain, and inflammatory pain. Piezo channels significantly impact pain perception and transmission. These channels' critical involvement in various pain types highlights their potential as promising targets for chronic pain therapy.

Summary

This review discusses the role of Piezo channels in chronic pain. By understanding these pain mechanisms, new therapeutic strategies can be developed to alleviate chronic pain, offering hope for patients suffering from these debilitating conditions.

Forkhead box C1 promotes the pathology of osteoarthritis in subchondral bone osteoblasts via the Piezo1/YAP axis

Subchondral bone sclerosis is a key characteristic of osteoarthritis (OA). Prior research has shown that Forkhead box C1 (FoxC1) plays a role in the synovial inflammation of OA, but its specific role in the subchondral bone of OA has not been explored. Our research revealed elevated expression levels of FoxC1 and Piezo1 in OA subchondral bone tissues. Further experiments on OA subchondral bone osteoblasts with FoxC1 or Piezo1 overexpression showed increased cell proliferation activity, expression of Yes-associated Protein 1 (YAP) and osteogenic markers, and secretion of proinflammatory factors. Mechanistically, the overexpression of FoxC1 through Piezo1 activation, in combination with downstream YAP signaling, led to increased levels of alkaline phosphatase (ALP), collagen type 1 (COL1) A1, RUNX2, Osteocalcin, matrix metalloproteinase (MMP) 3, and MMP9 expression. Notably, inhibition of Piezo1 reversed the regulatory function of FoxC1. The binding of FoxC1 to the targeted area (ATATTTATTTA, residues +612 to +622) and the activation of Piezo1 transcription were verified by the dual luciferase assays. Additionally, Reduced subchondral osteosclerosis and microangiogenesis were observed in knee joints from FoxC1-conditional knockout (CKO) and Piezo1-CKO mice, indicating reduced lesions. Collectively, our study reveals the significant involvement of FoxC1 in the pathologic process of OA subchondral bone via the Piezo1/YAP signaling pathway, potentially establishing a novel therapeutic target.

Force versus Response: Methods for Activating and Characterizing Mechanosensitive Ion Channels and GPCRs

Mechanotransduction is the process whereby cells convert mechanical signals into electrochemical responses, where mechanosensitive proteins mediate this interaction. To characterize these critical proteins, numerous techniques have been developed that apply forces and measure the subsequent cellular responses. While these approaches have given insight into specific aspects of many such proteins, subsequent validation and cross-comparison between techniques remain difficult given significant variations in reported activation thresholds and responses for the same protein across different studies. Accurately determining mechanosensitivity responses for various proteins, however, is essential for understanding mechanotransduction and potential physiological implications, including therapeutics. This critical review provides an assessment of current and emerging approaches used for mechanosensitive ion channel and G-Coupled Receptors (GPCRs) stimulation and measurement, with a specific focus on the ability to quantitatively measure mechanosensitive responses.

Sonogenetics in the Treatment of Chronic Diseases: A New Method for Cell Regulation

Sonogenetics is an innovative technology that integrates ultrasound with genetic editing to precisely modulate cellular activities in a non-invasive manner. This method entails introducing and activating mechanosensitive channels on the cell membrane of specific cells using gene delivery vectors. When exposed to ultrasound, these channels can be manipulated to open or close, thereby impacting cellular functions. Sonogenetics is currently being used extensively in the treatment of various chronic diseases, including Parkinson's disease, vision restoration, and cancer therapy. This paper provides a comprehensive review of key components of sonogenetics and focuses on evaluating its prospects and potential challenges in the treatment of chronic disease.

PIEZO-dependent mechanosensing is essential for intestinal stem cell fate decision and maintenance

Stem cells perceive and respond to biochemical and physical signals to maintain homeostasis. Yet, it remains unclear how stem cells sense mechanical signals from their niche in vivo. In this work, we investigated the roles of PIEZO mechanosensitive channels in the intestinal stem cell (ISC) niche. We used mouse genetics and single-cell RNA sequencing analysis to assess the requirement for PIEZO channels in ISC maintenance. In vivo measurement of basement membrane stiffness showed that ISCs reside in a more rigid microenvironment at the bottom of the crypt. Three-dimensional and two-dimensional organoid systems combined with bioengineered substrates and a stretching device revealed that PIEZO channels sense extracellular mechanical stimuli to modulate ISC function. This study delineates the mechanistic cascade of PIEZO activation that coordinates ISC fate decision and maintenance.

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.

Mechanisms of mechanotransduction and physiological roles of PIEZO channels

Mechanical force is an essential physical element that contributes to the formation and function of life. The discovery of the evolutionarily conserved PIEZO family, including PIEZO1 and PIEZO2 in mammals, as bona fide mechanically activated cation channels has transformed our understanding of how mechanical forces are sensed and transduced into biological activities. In this Review, I discuss recent structure-function studies that have illustrated how PIEZO1 and PIEZO2 adopt their unique structural design and curvature-based gating dynamics, enabling their function as dedicated mechanotransduction channels with high mechanosensitivity and selective cation conductivity. I also discuss our current understanding of the physiological and pathophysiological roles mediated by PIEZO channels, including PIEZO1-dependent regulation of development and functional homeostasis and PIEZO2-dominated mechanosensation of touch, tactile pain, proprioception and interoception of mechanical states of internal organs. Despite the remarkable progress in PIEZO research, this Review also highlights outstanding questions in the field.

Piezo1: the key regulators in central nervous system diseases

The occurrence and development of central nervous system (CNS) diseases is a multi-factor and multi-gene pathological process, and their diagnosis and treatment have always posed a serious challenge in the medical field. Therefore, exploring the relevant factors in the pathogenesis of CNS and improving the diagnosis and treatment rates has become an urgent problem. Piezo1 is a recently discovered mechanosensitive ion channel that opens in response to mechanical stimuli. A number of previous studies have shown that the Piezo channel family plays a crucial role in CNS physiology and pathology, especially in diseases related to CNS development and mechanical stimulation. This article comprehensively describes the biological properties of Piezo1, focuses on the potential association between Piezo1 and CNS disorders, and explores the pharmacological roles of Piezo1 agonists and inhibitors in treating CNS disorders.

Single-Cell Hypertrophy Promotes Contractile Function of Cultured Human Airway Smooth Muscle Cells via Piezo1 and YAP Auto-Regulation

Severe asthma is characterized by increased cell volume (hypertrophy) and enhanced contractile function (hyperresponsiveness) of the airway smooth muscle cells (ASMCs). The causative relationship and underlying regulatory mechanisms between them, however, have remained unclear. Here, we manipulated the single-cell volume of in vitro cultured human ASMCs to increase from 2.7 to 5.2 and 8.2 × 103 μm3 as a simulated ASMC hypertrophy by culturing the cells on micropatterned rectangular substrates with a width of 25 μm and length from 50 to 100 and 200 μm, respectively. We found that as the cell volume increased, ASMCs exhibited a pro-contractile function with increased mRNA expression of contractile proteins, increased cell stiffness and traction force, and enhanced response to contractile stimulation. We also uncovered a concomitant increase in membrane tension and Piezo1 mRNA expression with increasing cell volume. Perhaps more importantly, we found that the enhanced contractile function due to cell volume increase was largely attenuated when membrane tension and Piezo1 mRNA expression were downregulated, and an auto-regulatory loop between Piezo1 and YAP mRNA expression was also involved in perpetuating the contractile function. These findings, thus, provide convincing evidence of a direct link between hypertrophy and enhanced contractile function of ASMCs that was mediated via Piezo1 mRNA expression, which may be specifically targeted as a novel therapeutic strategy to treat pulmonary diseases associated with ASMC hypertrophy such as severe asthma.

Measuring Piezo1 and Actin Polarity in Chemokine-Stimulated Jurkat Cells During Live-Cell Imaging

The process of T-lymphocyte migration involves a complex interplay of chemical and mechanical signals. Mechanotransduction mechanisms in T lymphocytes enable them to efficiently navigate through diverse architectural and topographical features of the dynamic tissue macro- and micro-niches encountered during immune responses. Piezo1 mechanosensors are crucial for driving optimal T-cell migration by driving actin-cytoskeletal remodeling. Chemokine-stimulated T lymphocytes demonstrate significant asymmetry or polarity of Piezo1 and actin along the cell axis. The establishment and maintenance of polarity in migrating cells are paramount for facilitating coordinated and directional movements along gradients of chemokine signals. Live-cell imaging techniques are widely employed to study the trajectories of migrating cells. Our approach expands upon current methodologies by not only tracking migrating cells but also imaging fluorescently labeled cellular components. Specifically, our method enables measurement of protein enrichment in the front and rear halves of the moving cell by analyzing the temporal direction of cell trajectories, subsequently bisecting the cell into front-back halves, and measuring the intensities of the fluorescent signals in each cell half at each time frame. Our protocol also facilitates the quantification of the angular distribution of fluorescent signals, enabling visualization of the spatial distribution of signals relative to the direction of cell migration. The protocol describes the examination of polarity in chemokine-treated Jurkat cells transfected with Piezo1-mCherry and actin-GFP constructs. This approach can be extended to live-cell imaging and polarity assessment of other fluorescently labeled proteins. Key features • This experimental protocol allows real-time imaging of Jurkat cells expressing two fluorescent proteins (Piezo1 mCherry and actin-GFP). • Measures cell polarity by examining spatial enrichment of Piezo1 and actin proteins within the front and rear halves of a moving Jurkat cell. • The protocol enables analysis of cell polarity in 2D tracks of moving cells. • Polarity analysis includes measuring fluorescent signal intensities in front-rear halves of a moving cell and calculation of signal polarization angles relative to the cell trajectory.

Piezo channels modulate human lung fibroblast function

Bronchial airways and lung parenchyma undergo both static and dynamic stretch in response to normal breathing as well as in the context of insults such as mechanical ventilation (MV) or in diseases such as asthma and chronic obstructive pulmonary disease (COPD) which lead to airway remodeling involving increased extracellular matrix (ECM) production. Here, the role of fibroblasts is critical, but the relationship between stretch- and fibroblast-induced ECM remodeling under these conditions is not well-explored. Piezo (PZ) channels play a role in mechanotransduction in many cell and organ systems, but their role in mechanical stretch-induced airway remodeling is not known. To explore this, we exposed human lung fibroblasts to 10% static stretch on a background of 5% oscillations for 48 h, with no static stretch considered controls. Collagen I, fibronectin, alpha-smooth muscle actin (α-SMA), and Piezo 1 (PZ1) expression was determined in the presence or absence of Yoda1 (PZ1 agonist) or GsMTx4 (PZ1 inhibitor). Collagen I, fibronectin, and α-SMA expression was increased by stretch and Yoda1, whereas pretreatment with GsMTx4 or knockdown of PZ1 by siRNA blunted this effect. Acute stretch in the presence and absence of Yoda1 demonstrated activation of the ERK pathway but not Smad. Measurement of [Ca2+]i responses to histamine showed significantly greater responses following stretch, effects that were blunted by knockdown of PZ1. Our findings identify an essential role for PZ1 in mechanical stretch-induced production of ECM mediated by ERK phosphorylation and Ca2+ influx in lung fibroblasts. Targeting PZ channels in fibroblasts may constitute a novel approach to ameliorate airway remodeling by decreasing ECM deposition.NEW & NOTEWORTHY The lung is an inherently mechanosensitive organ that can respond to mechanical forces in adaptive or maladaptive ways, including via remodeling resulting in increased fibrosis. We explored the mechanisms that link mechanical forces to remodeling using human lung fibroblasts. We found that mechanosensitive Piezo channels increase with stretch and mediate extracellular matrix formation and the fibroblast-to-myofibroblast transition that occurs with stretch. Our data highlight the importance of Piezo channels in lung mechanotransduction toward remodeling.

Mobilization of Endogenous CD34+/CD133+ Endothelial Progenitor Cells by Enhanced External Counter Pulsation for Treatment of Refractory Angina

Adult stem cell therapy via intramyocardial injection of autologous CD34+ stem cells has been shown to improve exercise capacity and reduce angina frequency and mortality in patients with refractory angina (RA). However, the cost of such therapy is a limitation to its adoption in clinical practice. Our goal was to determine whether the less costly, less invasive, and widely accessible, FDA-approved alternative treatment for RA patients, known as enhanced external counterpulsation (EECP), mobilizes endogenous CD34+ stem cells and whether such mobilization is associated with the clinical benefits seen with intramyocardial injection. We monitored changes in circulating levels of CD34+/CD133+ and CD34+/KDR+ cells in RA patients undergoing EECP therapy and in a comparator cohort of RA patients undergoing an exercise regimen known as cardiac rehabilitation. Changes in exercise capacity in both cohorts were monitored by measuring treadmill times (TT), double product (DP) scores, and Canadian Cardiovascular Society (CCS) angina scores between pre- and post-treatment treadmill stress tests. Circulating levels of CD34+/CD133+ cells increased in patients undergoing EECP and were significant (β = -2.38, p = 0.012) predictors of improved exercise capacity in these patients. CD34+/CD133+ cells isolated from RA patients could differentiate into endothelial cells, and their numbers increased during EECP therapy. Our results support the hypothesis that mobilized CD34+/CD133+ cells repair vascular damage and increase collateral circulation in RA patients. They further support clinical interventions that can mobilize adult CD34+ stem cells as therapy for patients with RA and other vascular diseases.

The mechanics of the retina: Müller glia role on retinal extracellular matrix and modelling

The retina is a highly heterogeneous tissue, both cell-wise but also regarding its extracellular matrix (ECM). The stiffness of the ECM is pivotal in retinal development and maturation and has also been associated with the onset and/or progression of numerous retinal pathologies, such as glaucoma, proliferative vitreoretinopathy (PVR), age-related macular degeneration (AMD), epiretinal membrane (ERM) formation or uveitis. Nonetheless, much remains unknown about the biomechanical milieu of the retina, and specifically the role that Müller glia play as principal mechanosensors and major producers of ECM constituents. So far, new approaches need to be developed to further the knowledge in the field of retinal mechanobiology for ECM-target applications to arise. In this review, we focus on the involvement of Müller glia in shaping and altering the retinal ECM under both physiological and pathological conditions and look into various biomaterial options to more accurately replicate the impact of matrix stiffness in vitro.

Matrix Viscoelasticity Tunes the Mechanobiological Behavior of Chondrocytes

In articular cartilage, the pericellular matrix acting as a specialized mechanical microenvironment modulates environmental signals to chondrocytes through mechanotransduction. Matrix viscoelastic alterations during cartilage development and osteoarthritis (OA) degeneration play an important role in regulating chondrocyte fate and cartilage matrix homeostasis. In recent years, scientists are gradually realizing the importance of matrix viscoelasticity in regulating chondrocyte function and phenotype. Notably, this is an emerging field, and this review summarizes the existing literatures to the best of our knowledge. This review provides an overview of the viscoelastic properties of hydrogels and the role of matrix viscoelasticity in directing chondrocyte behavior. In this review, we elaborated the mechanotransuction mechanisms by which cells sense and respond to the viscoelastic environment and also discussed the underlying signaling pathways. Moreover, emerging insights into the role of matrix viscoelasticity in regulating chondrocyte function and cartilage formation shed light into designing cell-instructive biomaterial. We also describe the potential use of viscoelastic biomaterials in cartilage tissue engineering and regenerative medicine. Future perspectives on mechanobiological comprehension of the viscoelastic behaviors involved in tissue homeostasis, cellular responses, and biomaterial design are highlighted. Finally, this review also highlights recent strategies utilizing viscoelastic hydrogels for designing cartilage-on-a-chip.

Interface-Mediated Neurogenic Signaling: The Impact of Surface Geometry and Chemistry on Neural Cell Behavior for Regenerative and Brain-Machine Interfacing Applications

Nanomaterial advancements have driven progress in central and peripheral nervous system applications such as tissue regeneration and brain-machine interfacing. Ideally, neural interfaces with native tissue shall seamlessly integrate, a process that is often mediated by the interfacial material properties. Surface topography and material chemistry are significant extracellular stimuli that can influence neural cell behavior to facilitate tissue integration and augment therapeutic outcomes. This review characterizes topographical modifications, including micropillars, microchannels, surface roughness, and porosity, implemented on regenerative scaffolding and brain-machine interfaces. Their impact on neural cell response is summarized through neurogenic outcome and mechanistic analysis. The effects of surface chemistry on neural cell signaling with common interfacing compounds like carbon-based nanomaterials, conductive polymers, and biologically inspired matrices are also reviewed. Finally, the impact of these extracellular mediated neural cues on intracellular signaling cascades is discussed to provide perspective on the manipulation of neuron and neuroglia cell microenvironments to drive therapeutic outcomes.

Mapping the unicellular transcriptome of the ascending thoracic aorta to changes in mechanosensing and mechanoadaptation during aging

Aortic stiffening is an inevitable manifestation of chronological aging, yet the mechano-molecular programs that orchestrate region- and layer-specific adaptations along the length and through the wall of the aorta are incompletely defined. Here, we show that the decline in passive cyclic distensibility is more pronounced in the ascending thoracic aorta (ATA) compared to distal segments of the aorta and that collagen content increases in both the medial and adventitial compartments of the ATA during aging. The single-cell RNA sequencing of aged ATA tissues reveals altered cellular senescence, remodeling, and inflammatory responses accompanied by enrichment of T-lymphocytes and rarefaction of vascular smooth muscle cells, compared to young samples. T lymphocyte clusters accumulate in the adventitia, while the activation of mechanosensitive Piezo-1 enhances vasoconstriction and contributes to the overall functional decline of ATA tissues. These results portray the immuno-mechanical aging of the ATA as a process that culminates in a stiffer conduit permissive to the accrual of multi-gerogenic signals priming to disease development.

Substrate stress relaxation regulates neural stem cell fate commitment

Adult neural stem cells (NSCs) reside in the dentate gyrus of the hippocampus, and their capacity to generate neurons and glia plays a role in learning and memory. In addition, neurodegenerative diseases are known to be caused by a loss of neurons and glial cells, resulting in a need to better understand stem cell fate commitment processes. We previously showed that NSC fate commitment toward a neuronal or glial lineage is strongly influenced by extracellular matrix stiffness, a property of elastic materials. However, tissues in vivo are not purely elastic and have varying degrees of viscous character. Relatively little is known about how the viscoelastic properties of the substrate impact NSC fate commitment. Here, we introduce a polyacrylamide-based cell culture platform that incorporates mismatched DNA oligonucleotide-based cross-links as well as covalent cross-links. This platform allows for tunable viscous stress relaxation properties via variation in the number of mismatched base pairs. We find that NSCs exhibit increased astrocytic differentiation as the degree of stress relaxation is increased. Furthermore, culturing NSCs on increasingly stress-relaxing substrates impacts cytoskeletal dynamics by decreasing intracellular actin flow rates and stimulating cyclic activation of the mechanosensitive protein RhoA. Additionally, inhibition of motor-clutch model components such as myosin II and focal adhesion kinase partially or completely reverts cells to lineage distributions observed on elastic substrates. Collectively, our results introduce a unique system for controlling matrix stress relaxation properties and offer insight into how NSCs integrate viscoelastic cues to direct fate commitment.

Piezo 1 and Piezo 2 in the Chemosensory Organs of Zebrafish (Danio rerio)

The ion channels Piezo 1 and Piezo 2 have been identified as membrane mechano-proteins. Studying mechanosensitive channels in chemosensory organs could help in understanding the mechanisms by which these channels operate, offering new therapeutic targets for various disorders. This study investigates the expression patterns of Piezo proteins in zebrafish chemosensory organs. For the first time, Piezo protein expression in adult zebrafish chemosensory organs is reported. In the olfactory epithelium, Piezo 1 immunolabels kappe neurons, microvillous cells, and crypt neurons, while Calretinin is expressed in ciliated sensory cells. The lack of overlap between Piezo 1 and Calretinin confirms Piezo 1's specificity for kappe neurons, microvillous cells, and crypt neurons. Piezo 2 shows intense immunoreactivity in kappe neurons, one-ciliated sensory cells, and multi-ciliated sensory cells, with overlapping Calretinin expression, indicating its olfactory neuron nature. In taste buds, Piezo 1 immunolabels Merkel-like cells at the bases of cutaneous and pharyngeal taste buds and the light and dark cells of cutaneous and oral taste buds. It also marks the dark cells of pharyngeal taste buds and support cells in oral taste buds. Piezo 2 is found in the light and dark cells of cutaneous and oral taste buds and isolated chemosensory cells. These findings provide new insights into the distribution of Piezo channels in zebrafish chemosensory organs, enhancing our understanding of their sensory processing and potential therapeutic applications.

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.

FGF signaling modulates mechanotransduction/WNT signaling in progenitors during tooth root development

Stem/progenitor cells differentiate into different cell lineages during organ development and morphogenesis. Signaling pathway networks and mechanotransduction are important factors to guide the lineage commitment of stem/progenitor cells during craniofacial tissue morphogenesis. Here, we used tooth root development as a model to explore the roles of FGF signaling and mechanotransduction as well as their interaction in regulating the progenitor cell fate decision. We show that Fgfr1 is expressed in the mesenchymal progenitor cells and their progeny during tooth root development. Loss of Fgfr1 in Gli1+ progenitors leads to hyperproliferation and differentiation, which causes narrowed periodontal ligament (PDL) space with abnormal cementum/bone formation leading to ankylosis. We further show that aberrant activation of WNT signaling and mechanosensitive channel Piezo2 occurs after loss of FGF signaling in Gli1-CreER;Fgfr1fl/fl mice. Overexpression of Piezo2 leads to increased osteoblastic differentiation and decreased Piezo2 leads to downregulation of WNT signaling. Mechanistically, an FGF/PIEZO2/WNT signaling cascade plays a crucial role in modulating the fate of progenitors during root morphogenesis. Downregulation of WNT signaling rescues tooth ankylosis in Fgfr1 mutant mice. Collectively, our findings uncover the mechanism by which FGF signaling regulates the fate decisions of stem/progenitor cells, and the interactions among signaling pathways and mechanotransduction during tooth root development, providing insights for future tooth root regeneration.

Osr2 functions as a biomechanical checkpoint to aggravate CD8+ T cell exhaustion in tumor

Alterations in extracellular matrix (ECM) architecture and stiffness represent hallmarks of cancer. Whether the biomechanical property of ECM impacts the functionality of tumor-reactive CD8+ T cells remains largely unknown. Here, we reveal that the transcription factor (TF) Osr2 integrates biomechanical signaling and facilitates the terminal exhaustion of tumor-reactive CD8+ T cells. Osr2 expression is selectively induced in the terminally exhausted tumor-specific CD8+ T cell subset by coupled T cell receptor (TCR) signaling and biomechanical stress mediated by the Piezo1/calcium/CREB axis. Consistently, depletion of Osr2 alleviates the exhaustion of tumor-specific CD8+ T cells or CAR-T cells, whereas forced Osr2 expression aggravates their exhaustion in solid tumor models. Mechanistically, Osr2 recruits HDAC3 to rewire the epigenetic program for suppressing cytotoxic gene expression and promoting CD8+ T cell exhaustion. Thus, our results unravel Osr2 functions as a biomechanical checkpoint to exacerbate CD8+ T cell exhaustion and could be targeted to potentiate cancer immunotherapy.

Deformability of Heterogeneous Red Blood Cells in Aging and Related Pathologies

Aging is interrelated with changes in red blood cell parameters and functionality. In this article, we focus on red blood cells (RBCs) and provide a review of the known changes associated with the characterization of RBC deformability in aging and related pathologies. The biophysical parameters complement the commonly used biochemical parameters and may contribute to a better understanding of the aging process. The power of the deformability measurement approach is well established in clinical settings. Measuring RBCs' deformability has the advantage of relative simplicity, and it reflects the complex effects developing in erythrocytes during aging. However, aging and related pathological conditions also promote heterogeneity of RBC features and have a certain impact on the variance in erythrocyte cell properties. The possible applications of deformability as an early biophysical biomarker of pathological states are discussed, and modulating PIEZO1 as a therapeutic target is suggested. The changes in RBCs' shape can serve as a proxy for deformability evaluation, leveraging single-cell analysis with imaging flow cytometry and artificial intelligence algorithms. The characterization of biophysical parameters of RBCs is in progress in humans and will provide a better understanding of the complex dynamics of aging.

Piezo1 - Serine/threonine-protein phosphatase 2A - Cofilin1 biochemical mechanotransduction axis controls F-actin dynamics and cell migration

This study sheds light on a ground-breaking biochemical mechanotransduction pathway and reveals how Piezo1 channels orchestrate cell migration. We observed an increased cell migration rate in HEK293T (HEK) cells treated with Yoda1, a Piezo1 agonist, or in HEK cells overexpressing Piezo1 (HEK + P). Conversely, a significant reduction in cell motility was observed in HEK cells treated with GsMTx4 (a channel inhibitor) or upon silencing Piezo1 (HEK-P). Our findings establish a direct correlation between alterations in cell motility, Piezo1 expression, abnormal F-actin microfilament dynamics, and the regulation of Cofilin1, a protein involved in severing F-actin microfilaments. Here, the conversion of inactive pCofilin1 to active Cofilin1, mediated by the serine/threonine-protein phosphatase 2A catalytic subunit C (PP2AC), resulted in increased severing of F-actin microfilaments and enhanced cell migration in HEK + P cells compared to HEK controls. However, this effect was negligible in HEK-P and HEK cells transfected with hsa-miR-133b, which post-transcriptionally inhibited PP2AC mRNA expression. In summary, our study suggests that Piezo1 regulates cell migration through a biochemical mechanotransduction pathway involving PP2AC-mediated Cofilin1 dephosphorylation, leading to changes in F-actin microfilament dynamics.

Magnetogenetics as a promising tool for controlling cellular signaling pathways

Magnetogenetics emerges as a transformative approach for modulating cellular signaling pathways through the strategic application of magnetic fields and nanoparticles. This technique leverages the unique properties of magnetic nanoparticles (MNPs) to induce mechanical or thermal stimuli within cells, facilitating the activation of mechano- and thermosensitive proteins without the need for traditional ligand-receptor interactions. Unlike traditional modalities that often require invasive interventions and lack precision in targeting specific cellular functions, magnetogenetics offers a non-invasive alternative with the capacity for deep tissue penetration and the potential for targeting a broad spectrum of cellular processes. This review underscores magnetogenetics' broad applicability, from steering stem cell differentiation to manipulating neuronal activity and immune responses, highlighting its potential in regenerative medicine, neuroscience, and cancer therapy. Furthermore, the review explores the challenges and future directions of magnetogenetics, including the development of genetically programmed magnetic nanoparticles and the integration of magnetic field-sensitive cells for in vivo applications. Magnetogenetics stands at the forefront of cellular manipulation technologies, offering novel insights into cellular signaling and opening new avenues for therapeutic interventions.