Membrane mobility agents. A new class of biologically active molecules

Kosower, Edward M.; Kosower, Nechama S.; Faltin, Zahava; Diver, Adrianna; Saltoun, Gilda; Frensdorff, Asher

doi:10.1016/0005-2736(74)90065-0

Cited by 44 publications

(13 citation statements)

References 14 publications

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“…Fusion can be induced experimentally by certain viruses (3) and chemical agents (4,5). Membrane-mobility agents are long-chain esters designed to promote motion of molecules in cell membranes.…”

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confidence: 99%

“…Membrane-mobility agents are long-chain esters designed to promote motion of molecules in cell membranes. Membrane-mobility agents, which enter cells via the small particles formed on dispersion in aqueous medium, promote the lateral mobility of certain ligand-membrane receptor complexes and inhibit cytokinesis in some types of cells (5)(6)(7)(8)(9). Membrane-mobility agents, especially 2-(2-methoxyethoxy)ethyl cis-8-(2-octylcyclopropyl)octanoate (A2C), are efficient promoters of cell fusion; the results obtained using a defined agent such as A2C have allowed the identification of stages in the overall fusion process and the formulation of a molecular mechanism for membrane fusion (10)(11)(12)(13).…”

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Membrane-mobility agent-promoted fusion of erythrocytes: fusibility is correlated with attack by calcium-activated cytoplasmic proteases on membrane proteins.

Kosower¹,

Glaser²,

Kosower³

1983

Proc. Natl. Acad. Sci. U.S.A.

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Rat, but not human, erythrocytes undergo fusion promoted by the membrane-mobility agent 2-(2-methoxyethoxy)-ethyl cis-8-(2-octylcyclopropyl)octanoate (A2C). The difference in behavior is correlated with rat erythrocyte membrane protein degradation caused by Ca2+-activated proteases. The human erythrocyte is deficient in such protease activity. Membrane protein degradation is a necessary, but not sufficient, requirement for membrane fusion. Membrane protein degradation probably releases membrane components from certain constraints. In addition, the motion of membrane components precedes fusion and must be promoted by reagents such as A2C, leading to the creation of fusion-potent lipid areas. This sequence of chemical and physical events occurs in other fusion processes.Membrane fusion is a ubiquitous cellular process, mediating such phenomena as fertilization, exocytosis, endocytosis, phagocytosis, and turnover of intracellular organelles (1, 2). Fusion can be induced experimentally by certain viruses (3) and chemical agents (4, 5). Membrane-mobility agents are long-chain esters designed to promote motion of molecules in cell membranes. Membrane-mobility agents, which enter cells via the small particles formed on dispersion in aqueous medium, promote the lateral mobility of certain ligand-membrane receptor complexes and inhibit cytokinesis in some types of cells (5-9). Membrane-mobility agents, especially 2-(2-methoxyethoxy)ethyl cis-8-(2-octylcyclopropyl)octanoate (A2C), are efficient promoters of cell fusion; the results obtained using a defined agent such as A2C have allowed the identification of stages in the overall fusion process and the formulation of a molecular mechanism for membrane fusion (10-13).We have previously found differences in the occurrence of A2C-induced fusion among various mammalian non-nucleated erythrocytes as well as among avian nucleated erythrocytes (12, 13): erythrocytes of some species fuse easily, whereas those of others do not. "Mixed fusion," that between fusible erythrocytes from different species, is promoted by A2C. Moreover, the potential for fusion is a transferable characteristic, fusion being induced by A2C in otherwise nonfusible cells if mixed with fusible erythrocytes (13). The molecular basis for the differences observed among the erythrocytes of various species and for the transfer of fusibility has not yet been clarified.We now show that the difference between fusible rat erythrocytes and the nonfusible human cells is correlated with proteolytic activity; degradation of rat cell membrane proteins is caused by a Ca2'-activated cytoplasmic protease(s). The human erythrocyte is deficient in this protease activity. Membrane protein degradation is shown to be a necessary, but not sufficient, prerequisite for membrane fusion. Release of membrane components from constraints imposed by the cytoskeleton, allowing membrane component mobility, is proposed as one of the steps in the fusion process. Furthermore, the mobility of the membrane components must be promoted by...

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confidence: 99%

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confidence: 99%

Membrane-mobility agent-promoted fusion of erythrocytes: fusibility is correlated with attack by calcium-activated cytoplasmic proteases on membrane proteins.

Kosower¹,

Glaser²,

Kosower³

1983

Proc. Natl. Acad. Sci. U.S.A.

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“…Interestingly, unsaturated fatty acids have been reported to influence the properties of mammalian cell membrane in vitro (29).…”

Section: Discussionmentioning

confidence: 99%

Effect of streptococcal lipids on Ehrlich ascites tumor cells.

Kigoshi

Kitajima

1981

Jpn.J.Pharmacol

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Abstract-The lipids extracted from group A hemolytic streptococci (strain Su, Blackmore and C203U) were examined for their antitumor effect against Ehrlich ascites carcinoma in mice. Total lipids were extracted from strep tococcal cells according to the method of Folch et al, and separated into 9 lipid fractions by thin-layer chromatography, using various solvent systems.Three fractions were compound lipids (diphosphatidyl glycerols, monoglucosyl diglycerides and diglucosyl diglycerides), and the remaining 6 fractions were neutral lipids such as free fatty acids, glycerides, sterols and sterol esters.For biological testing, the lipid fractions suspended in physiological saline containing Tween 20 (0.02%) were incubated with Ehrlich tumor cells at 37°C for 90 min, and the cell mixture was given intraperitoneally into mice thereafter. Among 9 lipid fractions, free fatty acids and monoglycerides from the streptococci examined were highly active in suppressing the development of ascites carcinoma in mice. Dipho sphatidyl glycerols from two strains of streptococci (Blackmore and C203U) were also effective in suppressing the tumor growth in mice. However, the other lipid fractions had little effect on the tumor growth.

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“…It has been suggested that it may be necessary, in addition to other requirements, for lipids in natural membranes to be in a fluid condition for fusion to occur [4,5]. Kosower et al, have suggested that some increase in local fluidity favours cell fusion [7] from work involving membrane mobility agents which promote motion through cell membranes [8] by inducing local disorder and which actively promote the fusion of hen erythrocytes under similar conditions to those used by Lucy et al In the present communication evidence will be presented which indicates that treatment of human erythrocyte ghost membranes with the fusogenic lipid glycerol mono-oleate leads to an increase in the fluidity of the membrane lipids, whereas the chemically related nonfusogenic lipid glycerol monostearate has no effect.…”

Section: Introductionmentioning

confidence: 99%