Stretch‐activated single ion channel currents in tissue‐cultured embryonic chick skeletal muscle.

Guharay, F; Sachs, Frederick

doi:10.1113/jphysiol.1984.sp015317

Cited by 931 publications

(500 citation statements)

References 41 publications

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“…A functional interaction between actin filament organization and stretch-activated channels has previously been recognized (53)(54)(55). The fact that rENaC directly interacts with cytoskeletal elements also supports its reported mechanosensitivity (23,32).…”

Section: Discussionsupporting

confidence: 53%

Regulation of Epithelial Sodium Channels by Short Actin Filaments

Berdiev

Prat

Cantiello

et al. 1996

Journal of Biological Chemistry

149

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Cytoskeletal elements play an important role in the regulation of ion transport in epithelia. We have studied the effects of actin filaments of different length on the ␣, ␤, ␥-rENaC (rat epithelial Na ؉ channel) in planar lipid bilayers. We found the following. 1) Short actin filaments caused a 2-fold decrease in unitary conductance and a 2-fold increase in open probability (P o ) of ␣,␤,␥-rENaC. 2) ␣,␤,␥-rENaC could be transiently activated by protein kinase A (PKA) plus ATP in the presence, but not in the absence, of actin. 3) ATP in the presence of actin was also able to induce a transitory activation of ␣,␤,␥-rENaC, although with a shortened time course and with a lower magnitude of change in P o . 4) DNase I, an agent known to prohibit elongation of actin filaments, prevented activation of ␣,␤,␥-rENaC by ATP or PKA plus ATP. 5) Cytochalasin D, added after rundown of ␣,␤,␥-rENaC activity following ATP or PKA plus ATP treatment, produced a second transient activation of ␣,␤,␥-rENaC. 6) Gelsolin, a protein that stabilizes polymerization of actin filaments at certain lengths, evoked a sustained activation of ␣,␤,␥-rENaC at actin/gelsolin ratios of <32:1, with a maximal effect at an actin/gelsolin ratio of 2:1. These results suggest that short actin filaments activate ␣,␤,␥-rENaC. PKA-mediated phosphorylation augments activation of this channel by decreasing the rate of elongation of actin filaments. These results are consistent with the hypothesis that cloned ␣,␤,␥-rENaCs form a core conduction unit of epithelial Na ؉ channels and that interaction of these channels with other associated proteins, such as short actin filaments, confers regulation to channel activity.Membrane transport protein-cytoskeleton interactions are thought to be important not only for restricting various transporters to specific membrane domains, especially in epithelia, but also for regulating transport activity (1, 2). Actin networks interact with the plasma membrane either by direct binding (3, 4) or through anchoring proteins, including actin-binding protein (filamin), spectrin (fodrin, the non-erythroid form of spectrin), and ankyrin (5-8). The actin cytoskeleton has been shown to interact with a variety of transmembrane proteins, including ion transport molecules such as the band 3 anion exchanger (9), the epithelial Na ϩ /K ϩ -ATPase (6, 10), rat brain voltage-sensitive Na ϩ channels (11, 12), the Na ϩ -K ϩ -Cl Ϫ cotransporter (13), and the Na ϩ -H ϩ exchanger (14). Recently, functional interactions between the actin cytoskeleton and ion channels have been demonstrated for Na ϩ channel activity in epithelial cells (15), N-methyl-D-aspartic acid-activated channels in neurons (16), the Na ϩ /K ϩ -ATPase (17), a renal K ϩ channel (18), and two epithelial anion channels (namely, a renal Cl Ϫ channel (19) and the cystic fibrosis transmembrane conductance regulator (20, 21)). Apically located, renal amiloride-sensitive Na ϩ channels have also been shown to be associated directly with the actin-based membrane cytoskeleton (15, 22). Moreov...

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Section: Discussionsupporting

confidence: 53%

Regulation of Epithelial Sodium Channels by Short Actin Filaments

Berdiev

Prat

Cantiello

et al. 1996

Journal of Biological Chemistry

149

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“…It is worth noting in this respect that applying suction to patches showing spontaneous activity did not increase channel activity further in a graded manner like that shown in Fig. 5 The channels in C2 myoblasts and myotubes are similar to the stretch-activated channels in adult skeletal muscle (Brehm, Kullberg & Moody-Corbett, 1984;Guharay & Sachs, 1984, 1985. They are cation-selective and have a conductance in Na+-containing saline of 30-35 pS.…”

Section: Discussionmentioning

confidence: 65%

“…5A, however, suggests the increase in open probability with pressure may result from a decrease in the longer closed periods (cf. Guharay & Sachs, 1984 (Guharay & Sachs, 1985), E. coli (Martinac, Buechner, Delcour, Adler & Kung, 1987) and yeast (Gustin, Zhou, Martinac & Kung, 1988). Figure 6 shows a recording from a cell-attached patch on a myoblast before and after applying 20 mmHg of suction at + 40 mV (top traces) and -60 mV (bottom traces).…”

Section: Stretch-sensitive Gatingmentioning

confidence: 99%

Stretch‐sensitive channels in developing muscle cells from a mouse cell line.

Franco

Lansman

1990

The Journal of Physiology

110

121

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4. Channel openings occurred as bursts of brief openings and closings separated by much longer closed periods. Closed-time histograms were best fitted with three exponential components, while histograms of burst duration were best fitted with two exponential components, reflecting the short and long bursts in the single-channel records.5. Applying suction to the patch electrode while recording at steady negative membrane potentials produced channel openings to discrete current levels. Mean channel open probability depended linearly on the square of the applied pressure and was greater at positive membrane potentials. The permeability of the channel to monovalent and divalent cations was indistinguishable from the spontaneous activity recorded at steady negative potentials.6. Channel activity recorded from cell-attached patches in the absence of applied pressure depended on membrane potential increasing -e-fold per 38 mV with depolarization. Analysis of the kinetics of the response to membrane potential * To whom correspondence should be addressed. MS 7995A. FRANCO AND J. B. LANSMAN showed that the depolarization reduced the duration of the slowest component of the closed-time distribution.7. The lanthanide cation gadolinium (Gd) reduced the amplitude of the unitary currents in a concentration-dependent manner. The amplitudes of both inward and outward currents were reduced to the same extent suggesting block is voltageindependent. Gd produced half-maximal inhibition of the unitary current at 6 aM.8. The fraction of recordings from cell-attached patches showing stretch-activated and spontaneous channel activity was determined at morphologically identifiable stages of myogenesis. Stretch-sensitive activity was high in myoblasts plated at low density, but decreased during development. The fraction of patches showing spontaneous activity was low and remained constant during muscle differentiation.9. The results are discussed in terms of the possibility that cation channels in developing muscle cells are gated by changes in membrane tension and voltage. The role of Ca2+-permeable cation channels in providing a pathway for Ca2+ influx during the early stages of myogenesis is considered.

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“…Actual receptors for sensing pressure and movement have been described in single-celled organisms, and have parallels in mammalian sense organs. The first described mechanosensor was a stretch-activated channel that could respond directly to membrane perturbation (Guharay and Sachs, 1984). A channel of this type was purified from E. coli: the mechanosensitive channel large conductance (MscL) forms a nonselective ion channel (Sukharev et al, 1997) that responds to hyperosmotic tension.…”

Section: Candidate Mechanoreceptorsmentioning

confidence: 99%

Molecular pathways mediating mechanical signaling in bone

Rubin

Jacobs

2006

Gene

403

303

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Bone tissue has the capacity to adapt to its functional environment such that its morphology is "optimized" for the mechanical demand. The adaptive nature of the skeleton poses an interesting set of biological questions (e.g., how does bone sense mechanical signals, what cells are the sensing system, what are the mechanical signals that drive the system, what receptors are responsible for transducing the mechanical signal, what are the molecular responses to the mechanical stimuli). Studies of the characteristics of the mechanical environment at the cellular level, the forces that bone cells recognize, and the integrated cellular responses are providing new information at an accelerating speed. This review first considers the mechanical factors that are generated by loading in the skeleton, including strain, stress and pressure. Mechanosensitive cells placed to recognize these forces in the skeleton, osteoblasts, osteoclasts, osteocytes and cells of the vasculature are reviewed. The identity of the mechanoreceptor(s) is approached, with consideration of ion channels, integrins, connexins, the lipid membrane including caveolar and noncaveolar lipid rafts and the possibility that altering cell shape at the membrane or cytoskeleton alters integral signaling protein associations. The distal intracellular signaling systems on-line after the mechanoreceptor is activated are reviewed, including those emanating from G-proteins (e.g., intracellular calcium shifts), MAPKs, and nitric oxide. The ability to harness mechanical signals to improve bone health through devices and exercise is broached. Increased appreciation of the importance of the mechanical environment in regulating and determining the structural efficacy of the skeleton makes this an exciting time for further exploration of this area.

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Stretch‐activated single ion channel currents in tissue‐cultured embryonic chick skeletal muscle.

Cited by 931 publications

References 41 publications

Regulation of Epithelial Sodium Channels by Short Actin Filaments

Regulation of Epithelial Sodium Channels by Short Actin Filaments

Stretch‐sensitive channels in developing muscle cells from a mouse cell line.

Molecular pathways mediating mechanical signaling in bone

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