1
|
Zhang K, Wang L, Liu Z, Geng B, Teng Y, Liu X, Yi Q, Yu D, Chen X, Zhao D, Xia Y. Mechanosensory and mechanotransductive processes mediated by ion channels in articular chondrocytes: Potential therapeutic targets for osteoarthritis. Channels (Austin) 2021; 15:339-359. [PMID: 33775217 PMCID: PMC8018402 DOI: 10.1080/19336950.2021.1903184] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 02/06/2023] Open
Abstract
Articular cartilage consists of an extracellular matrix including many proteins as well as embedded chondrocytes. Articular cartilage formation and function are influenced by mechanical forces. Hind limb unloading or simulated microgravity causes articular cartilage loss, suggesting the importance of the healthy mechanical environment in articular cartilage homeostasis and implying a significant role of appropriate mechanical stimulation in articular cartilage degeneration. Mechanosensitive ion channels participate in regulating the metabolism of articular chondrocytes, including matrix protein production and extracellular matrix synthesis. Mechanical stimuli, including fluid shear stress, stretch, compression and cell swelling and decreased mechanical conditions (such as simulated microgravity) can alter the membrane potential and regulate the metabolism of articular chondrocytes via transmembrane ion channel-induced ionic fluxes. This process includes Ca2+ influx and the resulting mobilization of Ca2+ that is due to massive released Ca2+ from stores, intracellular cation efflux and extracellular cation influx. This review brings together published information on mechanosensitive ion channels, such as stretch-activated channels (SACs), voltage-gated Ca2+ channels (VGCCs), large conductance Ca2+-activated K+ channels (BKCa channels), Ca2+-activated K+ channels (SKCa channels), voltage-activated H+ channels (VAHCs), acid sensing ion channels (ASICs), transient receptor potential (TRP) family channels, and piezo1/2 channels. Data based on epithelial sodium channels (ENaCs), purinergic receptors and N-methyl-d-aspartate (NMDA) receptors are also included. These channels mediate mechanoelectrical physiological processes essential for converting physical force signals into biological signals. The primary channel-mediated effects and signaling pathways regulated by these mechanosensitive ion channels can influence the progression of osteoarthritis during the mechanosensory and mechanoadaptive process of articular chondrocytes.
Collapse
Affiliation(s)
- Kun Zhang
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Lifu Wang
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Zhongcheng Liu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Bin Geng
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Yuanjun Teng
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Xuening Liu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Qiong Yi
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Dechen Yu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Xiangyi Chen
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Dacheng Zhao
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Yayi Xia
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| |
Collapse
|
2
|
DEG/ENaC Ion Channels in the Function of the Nervous System: From Worm to Man. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:165-192. [DOI: 10.1007/978-981-16-4254-8_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
3
|
Mechanical Strain-Mediated Tenogenic Differentiation of Mesenchymal Stromal Cells Is Regulated through Epithelial Sodium Channels. Stem Cells Int 2020; 2020:5385960. [PMID: 32908542 PMCID: PMC7450316 DOI: 10.1155/2020/5385960] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/18/2020] [Accepted: 07/11/2020] [Indexed: 11/17/2022] Open
Abstract
It has been suggested that mechanical strain may elicit cell differentiation in adult somatic cells through activation of epithelial sodium channels (ENaC). However, such phenomenon has not been previously demonstrated in mesenchymal stromal cells (MSCs). The present study was thus conducted to investigate the role of ENaC in human bone marrow-derived MSCs (hMSCs) tenogenic differentiation during uniaxial tensile loading. Passaged-2 hMSCs were seeded onto silicone chambers coated with collagen I and subjected to stretching at 1 Hz frequency and 8% strain for 6, 24, 48, and 72 hours. Analyses at these time points included cell morphology and alignment observation, immunocytochemistry and immunofluorescence staining (collagen I, collagen III, fibronectin, and N-cadherin), and gene expression (ENaC subunits, and tenogenic markers). Unstrained cells at similar time points served as the control group. To demonstrate the involvement of ENaC in the differentiation process, an ENaC blocker (benzamil) was used and the results were compared to the noninhibited hMSCs. ENaC subunits' (α, β, γ, and δ) expression was observed in hMSCs, although only α subunit was significantly increased during stretching. An increase in tenogenic genes' (collagen1, collagen3, decorin, tenascin-c, scleraxis, and tenomodulin) and proteins' (collagen I, collagen III, fibronectin, and N-cadherin) expression suggests that hMSCs underwent tenogenic differentiation when subjected to uniaxial loading. Inhibition of ENaC function resulted in decreased expression of these markers, thereby suggesting that ENaC plays a vital role in tenogenic differentiation of hMSCs during mechanical loading.
Collapse
|
4
|
Matthewman C, Johnson CK, Miller DM, Bianchi L. Functional features of the "finger" domain of the DEG/ENaC channels MEC-4 and UNC-8. Am J Physiol Cell Physiol 2018; 315:C155-C163. [PMID: 29694233 DOI: 10.1152/ajpcell.00297.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNC-8 and MEC-4 are two members of the degenerin/epithelial Na+ channel (DEG/ENaC) family of voltage-independent Na+ channels that share a high degree of sequence homology and functional similarity. For example, both can be hyperactivated by genetic mutations [UNC-8(d) and MEC-4(d)] that induce neuronal death by necrosis. Both depend in vivo on chaperone protein MEC-6 for function, as demonstrated by the finding that neuronal death induced by hyperactive UNC-8 and MEC-4 channels is prevented by null mutations in mec-6. UNC-8 and MEC-4 differ functionally in three major ways: 1) MEC-4 is calcium permeable, whereas UNC-8 is not; 2) UNC-8, but not MEC-4, is blocked by extracellular calcium and magnesium in the micromolar range; and 3) MEC-6 increases the number of MEC-4 channels at the cell surface in oocytes but does not have this effect on UNC-8. We previously reported that Ca2+permeability of MEC-4 is conferred by the second transmembrane domain. We show here that the extracellular "finger" domain of UNC-8 is sufficient to mediate inhibition by divalent cations and that regulation by MEC-6 also depends on this region. Thus, our work confirms that the finger domain houses residues involved in gating of this channel class and shows for the first time that the finger domain also mediates regulation by chaperone protein MEC-6. Given that the finger domain is the most divergent region across the DEG/ENaC family, we speculate that it influences channel trafficking and function in a unique manner depending on the channel subunit.
Collapse
Affiliation(s)
- Cristina Matthewman
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine , Miami, Florida.,Neuroscience Program, University of Miami, Miller School of Medicine , Miami, Florida
| | - Christina K Johnson
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine , Miami, Florida
| | - David M Miller
- Department of Cell and Developmental Biology and Neuroscience Program, Vanderbilt University , Nashville, Tennessee
| | - Laura Bianchi
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine , Miami, Florida.,Neuroscience Program, University of Miami, Miller School of Medicine , Miami, Florida
| |
Collapse
|
5
|
Matthewman C, Miller-Fleming TW, Miller DM, Bianchi L. Ca2+ permeability and Na+ conductance in cellular toxicity caused by hyperactive DEG/ENaC channels. Am J Physiol Cell Physiol 2016; 311:C920-C930. [PMID: 27760755 DOI: 10.1152/ajpcell.00247.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/12/2016] [Indexed: 12/22/2022]
Abstract
Hyperactivated DEG/ENaC channels cause neuronal death mediated by intracellular Ca2+ overload. Mammalian ASIC1a channels and MEC-4(d) neurotoxic channels in Caenorhabditis elegans both conduct Na+ and Ca2+, raising the possibility that direct Ca2+ influx through these channels contributes to intracellular Ca2+ overload. However, we showed that the homologous C. elegans DEG/ENaC channel UNC-8(d) is not Ca2+ permeable, yet it is neurotoxic, suggesting that Na+ influx is sufficient to induce cell death. Interestingly, UNC-8(d) shows small currents due to extracellular Ca2+ block in the Xenopus oocyte expression system. Thus, MEC-4(d) and UNC-8(d) differ both in current amplitude and Ca2+ permeability. Given that these two channels show a striking difference in toxicity, we wondered how Na+ conductance vs. Ca2+ permeability contributes to cell death. To address this question, we built an UNC-8/MEC-4 chimeric channel that retains the calcium permeability of MEC-4 and characterized its properties in Xenopus oocytes. Our data support the hypothesis that for Ca2+-permeable DEG/ENaC channels, both Ca2+ permeability and Na+ conductance contribute to toxicity. However, for Ca2+-impermeable DEG/ENaCs (e.g., UNC-8), our evidence shows that constitutive Na+ conductance is sufficient to induce toxicity, and that this effect is enhanced as current amplitude increases. Our work further refines the contribution of different channel properties to cellular toxicity induced by hyperactive DEG/ENaC channels.
Collapse
Affiliation(s)
- Cristina Matthewman
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, Florida.,Neuroscience Program, University of Miami, Miller School of Medicine, Miami, Florida
| | | | - David M Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and.,Neuroscience Program, Vanderbilt University, Nashville, Tennessee
| | - Laura Bianchi
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, Florida; .,Neuroscience Program, University of Miami, Miller School of Medicine, Miami, Florida
| |
Collapse
|
6
|
Wang Y, Matthewman C, Han L, Miller T, Miller DM, Bianchi L. Neurotoxic unc-8 mutants encode constitutively active DEG/ENaC channels that are blocked by divalent cations. ACTA ACUST UNITED AC 2014; 142:157-69. [PMID: 23898007 PMCID: PMC3727304 DOI: 10.1085/jgp.201310974] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Ion channels of the DEG/ENaC family can induce neurodegeneration under conditions in which they become hyperactivated. The Caenorhabditis elegans DEG/ENaC channel MEC-4(d) encodes a mutant channel with a substitution in the pore domain that causes swelling and death of the six touch neurons in which it is expressed. Dominant mutations in the C. elegans DEG/ENaC channel subunit UNC-8 result in uncoordinated movement. Here we show that this unc-8 movement defect is correlated with the selective death of cholinergic motor neurons in the ventral nerve cord. Experiments in Xenopus laevis ooctyes confirm that these mutant proteins, UNC-8(G387E) and UNC-8(A586T), encode hyperactivated channels that are strongly inhibited by extracellular calcium and magnesium. Reduction of extracellular divalent cations exacerbates UNC-8(G387E) toxicity in oocytes. We suggest that inhibition by extracellular divalent cations limits UNC-8 toxicity and may contribute to the selective death of neurons that express UNC-8 in vivo.
Collapse
Affiliation(s)
- Ying Wang
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | | | | | | | | | | |
Collapse
|
7
|
Kamat S, Yeola S, Zhang W, Bianchi L, Driscoll M. NRA-2, a nicalin homolog, regulates neuronal death by controlling surface localization of toxic Caenorhabditis elegans DEG/ENaC channels. J Biol Chem 2014; 289:11916-11926. [PMID: 24567339 DOI: 10.1074/jbc.m113.533695] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hyperactivated DEG/ENaCs induce neuronal death through excessive cation influx and disruption of intracellular calcium homeostasis. Caenorhabditis elegans DEG/ENaC MEC-4 is hyperactivated by the (d) mutation and induces death of touch neurons. The analogous substitution in MEC-10 (MEC-10(d)) co-expressed in the same neurons is only mildly neurotoxic. We exploited the lower toxicity of MEC-10(d) to identify RNAi knockdowns that enhance neuronal death. We report here that knock-out of the C. elegans nicalin homolog NRA-2 enhances MEC-10(d)-induced neuronal death. Cell biological assays in C. elegans neurons show that NRA-2 controls the distribution of MEC-10(d) between the endoplasmic reticulum and the cell surface. Electrophysiological experiments in Xenopus oocytes support this notion and suggest that control of channel distribution by NRA-2 is dependent on the subunit composition. We propose that nicalin/NRA-2 functions in a quality control mechanism to retain mutant channels in the endoplasmic reticulum, influencing the extent of neuronal death. Mammalian nicalin may have a similar role in DEG/ENaC biology, therefore influencing pathological conditions like ischemia.
Collapse
Affiliation(s)
- Shaunak Kamat
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Shrutika Yeola
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Wenying Zhang
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Laura Bianchi
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida 33136.
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854.
| |
Collapse
|
8
|
Eastwood AL, Goodman MB. Insight into DEG/ENaC channel gating from genetics and structure. Physiology (Bethesda) 2012; 27:282-90. [PMID: 23026751 PMCID: PMC4012085 DOI: 10.1152/physiol.00006.2012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The founding members of the superfamily of DEG/ENaC ion channel proteins are C. elegans proteins that form mechanosensitive channels in touch and pain receptors. For more than a decade, the research community has used mutagenesis to identify motifs that regulate gating. This review integrates insight derived from unbiased in vivo mutagenesis screens with recent crystal structures to develop new models for activation of mechanically gated DEGs.
Collapse
Affiliation(s)
- Amy L. Eastwood
- Dept of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305-5345,
| | - Miriam B. Goodman
- Dept of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305-5345,
| |
Collapse
|