mechanosensitive channels/MSCs

GsMTx4 (5 μM) decreased Piezo1-mediated charge transfer to 38% of the starting level in HEK293 cells transfected with Piezo1 cDNA [1]. GsMTx4 (5 μM) inhibits smooth and skeletal muscle cells, cardiomyocytes, and astrocytes' cation-selective stretch-activated channels [2]. In mammary epithelial cells (MCF10A), leptin-induced AMPK and MLC-2 phosphorylation is dramatically reduced by GsMTx4 (2.5 μM, 16 hours) [3]. In organotypic cerebellar slices, GsMTx4 (500 nM, 48 h) attenuates demyelination caused by psychopyrimidine and cytotoxic lipids [4].

Stereotaxic injection (3 μM, 1 μL, single dose) reduces cerebral cortical demyelination and lysophosphatidylcholine-induced astrocyte toxicity while also having neuroprotective effects [4]. In the Von Frey test, GsMTx-4 (intraperitoneal injection, single dose 270 μg/kg) lessens mechanical allodynia brought on by inflammation and sciatic nerve damage [6].

GsMTx4 is a spider venom peptide that inhibits cationic mechanosensitive channels (MSCs). It has six lysine residues that have been proposed to affect membrane binding. We synthesized six analogs with single lysine-to-glutamate substitutions and tested them against Piezo1 channels in outside-out patches and independently measured lipid binding. Four analogs had ∼20% lower efficacy than the wild-type (WT) peptide. The equilibrium constants calculated from the rates of inhibition and washout did not correlate with the changes in inhibition. The lipid association strength of the WT GsMTx4 and the analogs was determined by tryptophan autofluorescence quenching and isothermal calorimetry with membrane vesicles and showed no significant differences in binding energy. Tryptophan fluorescence-quenching assays showed that both WT and analog peptides bound superficially near the lipid-water interface, although analogs penetrated deeper. Peptide-lipid association, as a function of lipid surface pressure, was investigated in Langmuir monolayers. The peptides occupied a large fraction of the expanded monolayer area, but that fraction was reduced by peptide expulsion as the pressure approached the monolayer-bilayer equivalence pressure. Analogs with compromised efficacy had pressure-area isotherms with steeper slopes in this region, suggesting tighter peptide association. The pressure-dependent redistribution of peptide between “deep” and “shallow” binding modes was supported by molecular dynamics (MD) simulations of the peptide-monolayer system under different area constraints. These data suggest a model placing GsMTx4 at the membrane surface, where it is stabilized by the lysines, and occupying a small fraction of the surface area in unstressed membranes. When applied tension reduces lateral pressure in the lipids, the peptides penetrate deeper acting as “area reservoirs” leading to partial relaxation of the outer monolayer, thereby reducing the effective magnitude of stimulus acting on the MSC gate.[1]

---

We have identified a 35 amino acid peptide toxin of the inhibitor cysteine knot family that blocks cationic stretch-activated ion channels. The toxin, denoted GsMTx-4, was isolated from the venom of the spider Grammostola spatulata and has <50% homology to other neuroactive peptides. It was isolated by fractionating whole venom using reverse phase HPLC, and then assaying fractions on stretch-activated channels (SACs) in outside-out patches from adult rat astrocytes. Although the channel gating kinetics were different between cell-attached and outside-out patches, the properties associated with the channel pore, such as selectivity for alkali cations, conductance ( approximately 45 pS at -100 mV) and a mild rectification were unaffected by outside-out formation. GsMTx-4 produced a complete block of SACs in outside-out patches and appeared specific since it had no effect on whole-cell voltage-sensitive currents. The equilibrium dissociation constant of approximately 630 nM was calculated from the ratio of association and dissociation rate constants. In hypotonically swollen astrocytes, GsMTx-4 produces approximately 40% reduction in swelling-activated whole-cell current. Similarly, in isolated ventricular cells from a rabbit dilated cardiomyopathy model, GsMTx-4 produced a near complete block of the volume-sensitive cation-selective current, but did not affect the anion current. In the myopathic heart cells, where the swell-induced current is tonically active, GsMTx-4 also reduced the cell size. This is the first report of a peptide toxin that specifically blocks stretch-activated currents. The toxin affect on swelling-activated whole-cell currents implicates SACs in volume regulation.[2]

Western Blot Analysis[3]
Cell Types: MCF10A Cell
Tested Concentrations: 2.5 μM
Incubation Duration: 16 hrs (hours)
Experimental Results: Leptin-induced phosphorylation of AMPK and MLC-2 was attenuated.

Animal/Disease Models: Male C57BL/6 mice (toxin induces focal demyelination in cortical brain tissue) [4]
Doses: 3 μM/1 μL, single dose.
Route of Administration: Stereotactic injection in the left and right cerebral hemispheres (sacrifice 4 days after injection)
Experimental Results: Prevented lysophosphatidylcholine (LPC)-induced enhanced increase in microglial reactivity and microglia number. Prevents LPC-mediated astrocyte toxicity by attenuating GFAP+ cells and reducing GFAP fluorescence intensity.

---

Animal/Disease Models: Male SD (SD (Sprague-Dawley)) rat sciatic nerve injury model [6]
Doses: 270 μg/kg, single dose
Route of Administration: intraperitoneal (ip) injection
Experimental Results: Reduce inflammation-induced mechanical allodynia.

[1]. GsMTx4: Mechanism of Inhibiting Mechanosensitive Ion Channels. Biophys J. 2017 Jan 10;112(1):31-45.

[2]. Identification of a peptide toxin from Grammostola spatulata spider venom that blocks cation-selective stretch-activated channels. J Gen Physiol. 2000 May;115(5):583-98.

[3]. Adipokine Leptin Co-operates With Mechanosensitive Ca 2 +-Channels and Triggers Actomyosin-Mediated Motility of Breast Epithelial Cells. Front Cell Dev Biol. 2021 Jan 6;8:607038.

[4]. Inhibition of Piezo1 attenuates demyelination in the central nervous system. Glia. 2020 Feb;68(2):356-375.

[5]. Stretch-activated ion channel Piezo1 directs lineage choice in human neural stem cells. Proc Natl Acad Sci U S A. 2014 Nov 11;111(45):16148-53.

[6]. A tarantula spider toxin, GsMTx4, reduces mechanical and neuropathic pain. Pain. 2008 Jul;137(1):208-217.

GsMTx4 is peptide that acts as a mechanosensitive ion channel blocker.
GsMtx-4 is a peptide found in tarantula venom that inhibits mechanosensitive ion channel (MSC) activity.

C185H273N49O45S6

4095.83845305443

4093.893

1209500-46-8

GsMTx4 TFA;D-GsMTx4 TFA;D-GsMTx4

90488987

H-Gly-DL-Cys(1)-DL-Leu-DL-Glu-DL-Phe-DL-Trp-DL-Trp-DL-Lys-DL-Cys(2)-DL-Asn-DL-Pro-DL-Asn-DL-Asp-DL-Asp-DL-Lys-DL-Cys(3)-DL-Cys(1)-DL-Arg-DL-Pro-DL-Lys-DL-Leu-DL-Lys-DL-Cys(2)-DL-Ser-DL-Lys-DL-Leu-DL-Phe-DL-Lys-DL-Leu-DL-Cys(3)-DL-Asn-DL-Phe-DL-Ser-DL-Phe-NH2

GCLEFWWKCNPNDDKCCRPKLKCSKLFKLCNFSF-NH2 (Disulfide bridge:Cys2-Cys17, Cys9-Cys17, Cys16-Cys30); GCLEFWWKCNPNDDKCCRPKLKCSKLFKLCNFSF

White to off-white solid powder

-12.7

52

59

75

285

9620

0

S1CC2C(NC(CCCNC(=N)N)C(N3CCCC3C(NC(C(NC(C(NC(C(NC3C(NC(C(NC(C(NC(C(NC(CC4C=CC=CC=4)C(NC(CCCCN)C(NC(CC(C)C)C(NC(C(NC(C(NC(C(NC(C(NC(C(N)=O)CC4C=CC=CC=4)=O)CO)=O)CC4C=CC=CC=4)=O)CC(N)=O)=O)CSSCC(C(N2)=O)NC(C(CCCCN)NC(C(CC(=O)O)NC(C(CC(=O)O)NC(C(CC(N)=O)NC(C2CCCN2C(C(CC(N)=O)NC(C(CSSC3)NC(C(CCCCN)NC(C(CC2=CNC3C=CC=CC2=3)NC(C(CC2=CNC3C=CC=CC2=3)NC(C(CC2C=CC=CC=2)NC(C(CCC(=O)O)NC(C(CC(C)C)NC(C(CS1)NC(CN)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)CC(C)C)=O)CCCCN)=O)CO)=O)=O)CCCCN)=O)CC(C)C)=O)CCCCN)=O)=O)=O

WVDNTWXIIKNMHY-UHFFFAOYSA-N

InChI=1S/C185H273N49O45S6/c1-98(2)72-121-160(255)203-114(54-27-33-65-188)156(251)229-141-96-284-283-95-140-178(273)225-134(84-147(195)239)184(279)234-71-39-60-144(234)182(277)224-131(83-146(194)238)170(265)222-133(86-151(245)246)172(267)223-132(85-150(243)244)171(266)206-116(56-29-35-67-190)158(253)230-142(97-285-282-94-139(177(272)221-130(82-145(193)237)169(264)218-127(79-105-46-19-12-20-47-105)166(261)226-136(91-236)174(269)211-120(152(196)247)76-102-40-13-9-14-41-102)231-163(258)124(75-101(7)8)214-153(248)112(52-25-31-63-186)204-164(259)125(77-103-42-15-10-16-43-103)217-162(257)123(74-100(5)6)213-154(249)113(53-26-32-64-187)207-173(268)135(90-235)227-179(141)274)180(275)232-138(176(271)210-119(58-37-69-199-185(197)198)183(278)233-70-38-59-143(233)181(276)209-117(155(250)212-121)57-30-36-68-191)93-281-280-92-137(202-148(240)87-192)175(270)215-122(73-99(3)4)161(256)208-118(61-62-149(241)242)159(254)216-126(78-104-44-17-11-18-45-104)165(260)219-129(81-107-89-201-111-51-24-22-49-109(107)111)168(263)220-128(80-106-88-200-110-50-23-21-48-108(106)110)167(262)205-115(157(252)228-140)55-28-34-66-189/h9-24,40-51,88-89,98-101,112-144,200-201,235-236H,25-39,52-87,90-97,186-192H2,1-8H3,(H2,193,237)(H2,194,238)(H2,195,239)(H2,196,247)(H,202,240)(H,203,255)(H,204,259)(H,205,262)(H,206,266)(H,207,268)(H,208,256)(H,209,276)(H,210,271)(H,211,269)(H,212,250)(H,213,249)(H,214,248)(H,215,270)(H,216,254)(H,217,257)(H,218,264)(H,219,260)(H,220,263)(H,221,272)(H,222,265)(H,223,267)(H,224,277)(H,225,273)(H,226,261)(H,227,274)(H,228,252)(H,229,251)(H,230,253)(H,231,258)(H,232,275)(H,241,242)(H,243,244)(H,245,246)(H4,197,198,199)

3-[77-[(2-aminoacetyl)amino]-30-[[4-amino-1-[[1-[[1-[(1-amino-1-oxo-3-phenylpropan-2-yl)amino]-3-hydroxy-1-oxopropan-2-yl]amino]-1-oxo-3-phenylpropan-2-yl]amino]-1,4-dioxobutan-2-yl]carbamoyl]-22,36,45,54,60,95-hexakis(4-aminobutyl)-4,13-bis(2-amino-2-oxoethyl)-39,86-dibenzyl-69-(3-carbamimidamidopropyl)-16,19-bis(carboxymethyl)-48-(hydroxymethyl)-89,92-bis(1H-indol-3-ylmethyl)-33,42,57,80-tetrakis(2-methylpropyl)-2,3a,5,11,14,17,20,23,32,35,38,41,44,47,50,53,56,59,62,68,71,78,81,84,87,90,93,96-octacosaoxo-a,27,28,74,75,99-hexathia-2a,3,6,12,15,18,21,24,31,34,37,40,43,46,49,52,55,58,61,67,70,79,82,85,88,91,94,97-octacosazapentacyclo[49.46.4.225,72.06,10.063,67]trihectan-83-yl]propanoic acid TFA salt

GsMTX 4; 1209500-46-8; GsMTx-4; H-Gly-DL-Cys(1)-DL-Leu-DL-Glu-DL-Phe-DL-Trp-DL-Trp-DL-Lys-DL-Cys(2)-DL-Asn-DL-Pro-DL-Asn-DL-Asp-DL-Asp-DL-Lys-DL-Cys(3)-DL-Cys(1)-DL-Arg-DL-Pro-DL-Lys-DL-Leu-DL-Lys-DL-Cys(2)-DL-Ser-DL-Lys-DL-Leu-DL-Phe-DL-Lys-DL-Leu-DL-Cys(3)-DL-Asn-DL-Phe-DL-Ser-DL-Phe-NH2; CHEBI:194078; GsMTX-4

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~50 mg/mL (~12.21 mM)
DMSO : ~50 mg/mL (~12.21 mM)

Solubility in Formulation 1: ≥ 1.25 mg/mL (0.31 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 1.25 mg/mL (0.31 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 1.25 mg/mL (0.31 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

 (Please use freshly prepared in vivo formulations for optimal results.)