Mechanical signal transduction are crucial for chondrocyte in response to mechanical cues during the growth, development and osteoarthritis (OA) of articular cartilage. Extracellular matrix (ECM) turnover regulates the matrix mechanical microenvironment of chondrocytes. Thus, understanding the mechanotransduction mechanisms during chondrocyte sensing the matrix mechanical microenvironment can develop effective targeted therapy for OA. In recent decades, growing evidences are rapidly advancing our understanding of the mechanical force-dependent cartilage remodeling and injury responses mediated by TRPV4 and PIEZOs. In this review, we highlighted the mechanosensing mechanism mediated by TRPV4 and PIEZOs during chondrocytes sensing mechanical microenvironment of the ECM. Additionally, the latest progress in the regulation of OA by inflammatory signals mediated by TRPV4 and PIEZOs was also introduced. These recent insights provide the potential mechanotheraputic strategies to target these channels and prevent cartilage degeneration associated with OA. This review will shed light on the pathogenesis of articular cartilage, searching clinical targeted therapies, and designing cell-induced biomaterials.
Chondrocytes ; TRPV Cation Channels ; Mechanotransduction, Cellular ; Biocompatible Materials ; Cartilage, Articular

Microenvironmental biophysical factors play a fundamental role in controlling cell behaviors including cell morphology, proliferation, adhesion and differentiation, and even determining the cell fate. Cells are able to actively sense the surrounding mechanical microenvironment and change their cellular morphology to adapt to it. Although cell morphological changes have been considered to be the first and most important step in the interaction between cells and their mechanical microenvironment, their regulatory network is not completely clear. In the current study, we generated silicon-based elastomer polydimethylsiloxane (PDMS) substrates with stiff (15:1, PDMS elastomer vs. curing agent) and soft (45:1) stiffnesses, which showed the Young's moduli of ~450 kPa and 46 kPa, respectively, and elucidated a new path in cytoskeleton re-organization in chondrocytes in response to changed substrate stiffnesses by characterizing the axis shift from the secreted extracellular protein laminin β1, focal adhesion complex protein FAK to microfilament bundling. We first showed the cellular cytoskeleton changes in chondrocytes by characterizing the cell spreading area and cellular synapses. We then found the changes of secreted extracellular linkage protein, laminin β1, and focal adhesion complex protein, FAK, in chondrocytes in response to different substrate stiffnesses. These two proteins were shown to be directly interacted by Co-IP and colocalization. We next showed that impact of FAK on the cytoskeleton organization by showing the changes of microfilament bundles and found the potential intermediate regulators. Taking together, this modulation axis of laminin β1-FAK-microfilament could enlarge our understanding about the interdependence among mechanosensing, mechanotransduction, and cytoskeleton re-organization.
Cell Adhesion ; Chondrocytes ; Cytoskeleton/metabolism* ; Elastomers/metabolism* ; Laminin/metabolism* ; Mechanotransduction, Cellular

Mechanical stimulus is critical to cardiovascular development during embryogenesis period.The mechanoreceptors of endocardial cells and cardiac myocytes may sense mechanical signals and initiate signal transduction that induce gene expression at a cellular level,and then translate molecular-level events into tissue-level deformations,thus guiding embryo development.This review summarizes the regulatory roles of mechanical signals in the early cardiac development including the formation of heart tube,looping,valve and septal morphogenesis,ventricular development and maturation.Further,we discuss the potential mechanical transduction mechanisms of platelet endothelial cell adhesion molecule 1-vascular endothelial-cadherin-vascular endothelial growth factor receptor 2 complex,primary cilia,ion channels,and other mechanical sensors that affect some cardiac malformations.
Animals ; Heart/embryology* ; Humans ; Mechanotransduction, Cellular ; Myocytes, Cardiac/physiology* ; Vascular Endothelial Growth Factor A/metabolism*

The reconstruction of tactile function during the repair of skin damage caused by factors including burns is inseparable from the functional regeneration of tactile receptor Merkel cells. Merkel cells mainly exist in the basal layer of the epidermis and are closely connected with nerves to form Merkel cell-nerve complexes, which play an important role in biological organisms. A large number of studies have shown that Merkel cells conduct precise transmission of mechanical force stimuli through the mechanically gated ion channels PIEZO2, and perform the function of tactile receptors. In this paper, we discussed the characteristics of Merkel cells and analyzed the different subgroups that may possibly exist in this type of cells and their functions, at the same time, we investigated the animal model research of touch-related diseases and the clinical diseases related to touch, revealing the importance of Merkel cell function research.
Animals ; Ion Channels/metabolism* ; Mechanotransduction, Cellular/physiology* ; Merkel Cells/physiology* ; Skin/metabolism* ; Touch/physiology*

Mechanosensitive (MS) channels are extensively studied membrane protein for maintaining intracellular homeostasis through translocating solutes and ions across the membrane, but its mechanisms of channel gating and ion selectivity are largely unknown. Here, we identified the YnaI channel as the Na/K cation-selective MS channel and solved its structure at 3.8 Å by cryo-EM single-particle method. YnaI exhibits low conductance among the family of MS channels in E. coli, and shares a similar overall heptamer structure fold with previously studied MscS channels. By combining structural based mutagenesis, quantum mechanical and electrophysiological characterizations, we revealed that ion selective filter formed by seven hydrophobic methionine (YnaI) in the transmembrane pore determined ion selectivity, and both ion selectivity and gating of YnaI channel were affected by accompanying anions in solution. Further quantum simulation and functional validation support that the distinct binding energies with various anions to YnaI facilitate Na/K pass through, which was defined as binding-block mechanism. Our structural and functional studies provided a new perspective for understanding the mechanism of how MS channels select ions driven by mechanical force.
Cryoelectron Microscopy ; Escherichia coli Proteins ; chemistry ; isolation & purification ; metabolism ; ultrastructure ; Ion Channels ; chemistry ; isolation & purification ; metabolism ; ultrastructure ; Mechanotransduction, Cellular ; Models, Molecular ; Quantum Theory

The sense of mechanical stimuli (e.g. force or deformation) in the environment underlies several important physiological processes, for example the perception of sound, touch, pain and acceleration. The key step in mechanosensation is to convert the extracellular mechanical stimuli into cellular electrical or chemical signals. This process is termed as mechanotransduction. Based on mechanical and electrophysiological measurements, "Gating-Spring" theory was proposed as a general model to describe the cell biological mechanism of mechanotransduction. However, despite efforts made in several model organisms, the molecular basis of the "Gating-Spring" model remains elusive. In recent years, several key progresses have been made using the mechanoreceptors of Drosophila melanogaster as the models. This article introduces the "Gating-Spring" theory and reviews the recent research progresses on the fly mechanotransduction.
Animals ; Drosophila melanogaster ; Mechanoreceptors ; Mechanotransduction, Cellular

Cells sense various in vivo mechanical stimuli, which initiate downstream signaling to mechanical forces. While a body of evidences is presented on the impact of limited mechanical regulators in past decades, the mechanisms how biomechanical responses globally affect cell function need to be addressed. Complexity and diversity of in vivo mechanical clues present distinct patterns of shear flow, tensile stretch, or mechanical compression with various parametric combination of its magnitude, duration, or frequency. Thus, it is required to understand, from the viewpoint of mechanobiology, what mechanical features of cells are, why mechanical properties are different among distinct cell types, and how forces are transduced to downstream biochemical signals. Meanwhile, those in vitro isolated mechanical stimuli are usually coupled together in vivo, suggesting that the different factors that are in effect individually could be canceled out or orchestrated with each other. Evidently, omics analysis, a powerful tool in the field of system biology, is advantageous to combine with mechanobiology and then to map the full-set of mechanically sensitive proteins and transcripts encoded by its genome. This new emerging field, namely mechanomics, makes it possible to elucidate the global responses under systematically-varied mechanical stimuli. This review discusses the current advances in the related fields of mechanomics and elaborates how cells sense external forces and activate the biological responses.
Biomechanical Phenomena ; Gene Expression Regulation ; Humans ; Mechanotransduction, Cellular ; Models, Biological ; Proteome ; genetics ; metabolism ; Stress, Physiological ; Transcriptome

Pinch-3 protein is an important constituent of cell membranes, which directly affects the cell morphology and mechanical properties. We observed and compared the change of morphology and cell traction force of glomerular podocytes before and after Pinch-3 gene inhibition by gene interference technology in this experiment. We found that a number of pores appeared on the cell surface, and the cell projected area were increased at the same time, with an approximate average about an increase of 40% after Pinch-3 gene inhibition. The results showed that the cell traction force of glomerular podocytes was significantly reduced, with an approximate average decrease of 40%, the maximum value of the cell traction force was reduced and the distribution of cell traction force became dispersive. All this suggested that after Pinch-3 gene inhibition, some pores created on the cell surface influenced the physical properties of glomerular podocytes and then affected the cell projected area and influenced the formation and distribution of cell traction force of the glomerular podocytes as well.
Adaptor Proteins, Signal Transducing ; genetics ; physiology ; Biomechanical Phenomena ; Cell Movement ; Genetic Engineering ; Humans ; Kidney Glomerulus ; cytology ; LIM Domain Proteins ; genetics ; physiology ; Mechanotransduction, Cellular ; physiology ; Membrane Proteins ; genetics ; physiology ; Podocytes ; cytology ; physiology ; Stress, Mechanical

Mechanical force has essential effects on cellular behaviors such as proliferation, migration and differentiation, and the mechanism of mechanotransduction is still one of the hot spots in mechanobiology study. Traditional methods could not provide accurate evaluation of the protein activation signal upon mechanical stress application. The development of fluorescence protein technology greatly promoted the understanding of mechanotransduction. In particular, genetically-encoded biosensors based on fluorescence resonance energy transfer (FRET) technique has achieved a real-time dynamic observation of living cell signal protein activity, which provides a powerful tool for the in-depth study of biomechanics. In this paper, we provide a summary on recent progress of FRET application in biomechanics. Firstly we introduce the FRET technology, and then we summarize three methods to integrate the mechanical stimulation with the FRET imaging system on cell experiments. After that, the important progress of biomechanical research on signal pathway made by FRET technology, such as cytoskeleton, Rho family, calcium and cellular physical stress visualization, are also discussed. Finally, we point out the bottleneck of the future development in FRET technology, and also make the prospect of the application of FRET in mechanotransduction. In summary, FRET technology provides a powerful tool for the studies of mechanotransduction, which will advance our systematic understanding on the molecular mechanisms about how cells respond to mechanical stimulation.
Biomechanical Phenomena ; Biosensing Techniques ; Fluorescence Resonance Energy Transfer ; Humans ; Luminescent Proteins ; chemistry ; Mechanotransduction, Cellular ; Microscopy, Fluorescence ; Signal Transduction ; Stress, Mechanical

Although the basic principles for the function of peripheral auditory system have been known for many years, the molecular mechanisms which affect deafness are not clear. In recent years, the study of hereditary deafness associated mouse models has revealed the molecular basis which is related with the formation and function of the hair bundle and the mechanosensory organelle of hair cell. This review focused on the role of protein network, which is formed by the proteins encoded by the Usher syndrome type 1 genes, in hair-bundle development and mechanotransducer channel gating. And the review also showed how the stereocilia rootlets contribute to the hair bundle's mechanical properties and how the hair bundle produces suppressive masking. Finally, the review revealed multiple roles of the tectorial membrane and extracellular matrix in the hair bundles stimulating in the cochlea.
Animals ; Cochlea ; physiopathology ; Disease Models, Animal ; Extracellular Matrix ; physiology ; Hair Cells, Auditory ; pathology ; Hearing Loss, Sensorineural ; genetics ; Humans ; Mechanotransduction, Cellular ; Mice ; Usher Syndromes ; genetics