Mechanosensitive

Sukharev, S. and Corey, D. P. Mechanosensitive channels multiplicity of families and gating paradigms. Sci. STKE... 

The molecular nature of the neuronal receptors is now becoming understood with the advent of molecular biological techniques. The molecular structure of the mechanosensitive channels has been established only recently. In principle mechanosensitive channels must be opened by mechanical deformation of the neural membrane in which they are em-... 

S. Sukharev and A. Anishkin. Mechanosensitive channels what can we learn from simple model systems TINS 27(6), 2004. 

Mechanosensitive ion channels can be looked at as membrane-embedded mechano-electrical switches. They play a critical role in transducing physical stresses at the cell membrane (e.g. lipid bilayer deformations) into an electrochemical response. Two types of stretch-activated channels have been reported the mechanosensitive channels of large conductance (MscL) and mechanosensitive channels of small conductance (MscS). 

Sukharev, S. (1999). Mechanosensitive channels in bacteria as membrane tension reporters, FASEB J., 13 (Suppl.), S55-S61. 

Bass, R. B., Strop, P., Barclay, M. and Rees, D. C. (2002). Crystal structure of Escherichia coli MscS, a voltage-modulated and mechanosensitive channel, Science, 298, 1582-1587. 

Sanderson MJ, Dirksen ER (1989) Mechanosensitive and beta-adrenergic control of the ciliary beat frequency of mammalian respiratory tract cells in culture. Am Rev Respir Dis 139(2) 432 140. 

GsMtx mechanosensitive toxin from spider Grammostola spatulata... 

The most important stimulus to the release of ANP from the heart is atrial stretch via mechanosensitive ion channels. ANP release is also increased by volume expansion, changing from the standing to the supine position, and exercise. ANP release can also be increased by sympathetic stimulation via aiA-adrenoceptors, endothelins via the -receptor subtype (see below), glucocorticoids, and vasopressin. Plasma ANP concentration increases in various pathologic states, including heart failure, primary aldosteronism, chronic renal failure, and inappropriate ADH secretion syndrome. 

Figure 2. A proposed model demonstrating several different prominent calcium-related pathways whose activity may be altered in dystrophic muscle. Increased activity of mechanosensitive channels (MS) and store-activated channels (SOC), which are likely derived from the same gene product (TRPC), and the calcium leak channel, which could represent a proteolyzed TRPC SOC channel. Decreased mechanical coupling between L-type VGCC and ryanodine receptors may increase basal calcium release from calcium stores (not shown). Further, increased IP, and IP, receptor levels may also enhance basal and stimulated calcium-induced calcium release (CICR) from calcium stores. Calcium store depletion can increase translocation of SOCs from intracellular vesicles to the sarcolemma. Finally, the relationship between increased membrane fragility and tearing is less certain, but calcium influx through sarcolemmal tears could lead to calcium-dependent proteolysis and increased activity of calcium leak channels, as well as proteolysis of other targets, and increased release of calcium from intracellular stores through CICR. This model is not meant to be comprehensive, and other calcium-related molecules are discussed in the text...

We should also note that Gu et al. (2001) showed mechanosensitivity in a Shaker-type channel, and suggest that mechanosensitivity might be a general property of multiconformational channels. Thus, the presence of mechanosensitivity might not be evidence of channel relatedness. 

Franco-Obregon, A., Jr., and Lansman, J.B., 1994, Mechanosensitive ion channels in skeletal muscle from normal and dystrophic mice, J Physiol, 481 ( Pt 2), pp 299-309. 

McBride, D.W., Jr., and Hamill, O.P., 1992, Pressure-clamp a method for rapid step perturbation of mechanosensitive channels, Pflugers Arch, 421, pp 606-612. 

Hughes S, Magnay J, Foreman M, Publicover SJ, Dobson JP, El Haj AJ. 2006. Expression of the mechanosensitive 2PK+ channel TREK-1 in human osteoblasts. J Cell Physiol 206 738—48. 

Lee HS, Millward-Sadler SJ, Wright MO, Nuki G, Salter DM. 2000. Integrin and mechanosensitive ion channel-dependent tyrosine phosphorylation of focal adhesion proteins and beta-catenin in human articular chondrocytes after mechanical stimulation. J Bone Miner Res 15 1501-9. 

Ryder KD, Duncan RL. 2001. Parathyroid hormone enhances fluid shear-induced [Ca2+]i signaling in osteoblastic cells through activation of mechanosensitive and voltage-sensitive Ca2+ channels. J Bone Miner Res 16 240-8. 

Cui, C., Smith, D.O. and Adler, J. (1995) Characterization of mechanosensitive channels in Eschericia cofi cytoplasmic cell membrane by whole-cell patch clamp recording. Journal of Membrane Biology 144 31-42... 

Morris, C.E. (1990) Mechanosensitive ion channels. Journal of Membrane Biology 113 93-107... 

Petrov, A.G. and Usherwood, P.N. (1994) Mechanosensitivity of cell membranes. Ion channels, lipid matrix and cytoskeleton. European Biophysics 23 1-19... 

Sackin, H. (1995) Mechanosensitive channels. Annual Review of Physiology 57 333-353... 

The baroreflex system consists of mechanosensitive receptors in the aorta and carotid sinus that detect changes in blood pressure. The receptors give rise to afferent nerve fibers that relay impulses to the CNS. Within the CNS, the afferent signals are processed and ultimately transmitted to efferent sympathetic and parasympathetic fibers to the vasculature and heart. Increases in blood pressure will increase baro-receptors activity leading to an inhibition of sympathetic impulses to the blood vessels (thereby relaxing them) and to the heart (decreasing heart rate and contractility). In addition, parasympathetic activity to the heart is increased leading to a reduction in heart rate and possibly contractility. 

Grammostola spatulata, which inhibits mechanosensitive ion channels ... 

Mechanosensitive channels respond to changes in membrane tension. A prokaryotic large-conductance mechanosensitive channel, MscL, opens in response to osmotic stress to form a water filled channel between 3 and 4 nm across [18]. The change in pressure on the bilayer imparts a small movement in a transmembrane helix that is then followed by a dramatic rearrangement of the transmembrane domain to a fully open state. 

Perozo E et al (2002) Open channel structure of MscL and the gating mechanism of mechanosensitive channels. Nature 418 942-948... 

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