The fusion of erythrocytes by fatty acids, esters, retinol and α-tocopherol

Abstract

1. The ability of a number of carboxylic acids, their esters, retinol and alpha-tocopherol to induce fusion of hen erythrocytes in vitro was investigated. 2. Some 30 different fat-soluble substances (100mug/ml) were found to cause the formation of multinucleated erythrocytes with a suspension of 3x10(8) erythrocytes/ml. The most effective agents induced fusion within 5-10min at 37 degrees C; some substances required about 1h. 3. Inclusion of Dextran 60C in the test medium minimized colloid osmotic lysis caused by exogenous lipids that induce cell fusion. 4. Cell swelling, followed by cell adhesion, was then seen to precede cell fusion. 5. Fusion occurred with C(10)-C(14) saturated carboxylic acids, with unsaturated, longer-chain carboxylic acids and their mono-esters; retinol, and to a lesser extent alpha-tocopherol, also caused cell fusion. 6. C(6)-C(9), C(15), C(16) and C(18) saturated carboxylic acids did not induce fusion within 4h; glyceryl dioleate was only weakly active, and glyceryl trioleate was inactive in the test system. 7. Fusion was facilitated by a high ratio of chemical agents to cell number and by incubation between pH5 and 6. It was inhibited by EDTA and by serum albumin. 8. Glyceryl mono-oleate caused both a similar fusion of several species of mammalian erythrocyte and the interspecific fusion of human and chicken erythrocytes. 9. The term ;fusogenic' is proposed to describe chemical, viral and physical agents that cause membranes to fuse. 10. The biochemical mechanisms involved and the possible biological significance of membrane fusion by fusogenic lipids are discussed.

Induction of membrane fusion by polysialogangliosides

“…In a case in which 3.3 mM Na2EDTA was present in the medium, the addition of glyceryl mono-oleate or GDa induced the appearance of rounded cells or of crenated or oddlyshaped cells, respectively, but neither membrane pinching off nor multinucleated cells were found. These observations indicate that as with other fusogenic agents [4][5][6] free Ca 2÷ is required for the ganglioside-induced fusion process.…”

“…1 a). VChen the fusogenic lipid glyceryl monooleate [4] was added to the basal medium the cells became rounded within 10 rain (fig.lb) and after 20-30 min bi-and multinudeated cells were seen, indicating extensive membrane fusion ( fig.1 c). Cells incubated for up to 4 h in the basal medium containing Cer, GlcCer, Gg4Cer, GMt or GM3 did not show changes with respect to the cells incubated in absence of added lipids.…”

“…Co. (London SW6). Induction of membrane fusion was carried out in a system similar to that in [4]. Briefly, washed chicken erythrocytes (approx.…”

Proteinases and cell fusion

“…was withdrawn into a sterile solution of citrate anticoagulant; erythrocytes were prepared and treated with oleoylglycerol [7] on the day of collection. (The presence of a leukocyte in the preparations used was an extremely rare event.)…”

Lipidic intramembranous particles

“…In other fusion mechanisms it has been postulated that special fusogenic lipids such as lysophosphatidylcholine [90], monoglycerides [91] or phosphotidylserine (PS) [92] play a pivotal role. In fact if there is a universal mechanism of the involvement of lipids in membrane fusion it is highly unlikely that one particular type of lipid is required in this process, both in light of high variability of lipid composition in membranes and lipid asymmetry.…”