Binding of Salmonella minnesota R-form glycolipid mR595 to rat fibroblasts and its effect on cell metabolism and cell behaviour
✍ Scribed by Réal Lallier; Michel Trudel; Carlos A. Brailovsky; Vijai N. Nigam
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- English
- Weight
- 833 KB
- Volume
- 98
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
Trypsinized normal rat embryo fibroblasts and untrypsinized and trypsinized transformed rat fibroblasts have two orders of binding sites for bacterial glycolipid mR595. The high order sites fix 1-3 pg glycolipid mR595/ lo5 cells and those of the low order fix about 6 pg glycolipid mR595/106 cells.
Ca++ is required for the low order glycolipid mR595 binding to be trypsinized but not to the untrypsinized transformed rat fibroblasts. The low order binding is temperature dependent with the transition temperature lying between 25 and 37°C. Exogenously added ganglioside and glycoproteins contained in the fetal calf serum do not inhibit fixation of glycolipid mR595. Only @-lipoprotein at high concentrations is slightly inhibitory.
Glycolipid mR595 fixation to transformed fibroblast does not alter their morphology and appears to slightly improve cell attachment to substratum. Glycolipid mR595 fixation results in a lengthening of the S-phase of the cell cycle and a reduction in 2-deoxyglucose uptake. Uptake of inorganic phosphate is not affected. Inhibition of phospholipid synthesis is observed in mR595 fixed fibroblasts whereas synthesis of cell surface glycoproteins and the content of cellular gangliosides is not affected.
In a previous publication (Bara et al., '73a), we showed that transformed rat embryo fibroblasts and trypsin or neuraminidase treated normal rat embryo fibroblasts fix bacterial glycolipid mR595 to their cell surface/cell membrane. Based on the action of trypsin and of neuraminidase, we proposed that hydrophobic fatty acid chains of the bacterial glycolipid interact with the hydrophobic portions of protein and lipid present in the membrane interior (Bara et al., '73b). It was also shown that fixation of bacterial glycolipid to transformed rat fibroblasts resulted in an increase in the intracellular cyclic AMP levels and temporary alteration in their saturation density from that of transformed phenotype to one of normal phenotype (Brailovsky et al., '73).
Considering that glycolipid mR595 fixation to transformed rat fibroblasts has an important effect of normalization of their growth pattern in vitro, we have, first, determined the conditions required for the fixation of gly-