RBL-2H3 Proliferation is Modulated by Treatments that Shift Transition Temperatures in Isolated Plasma Membrane Vesicles

Abstract

Giant plasma membrane vesicles (GPMVs) isolated from a variety of cell types appear homogeneous at physiological temperatures but separate into distinct liquid-ordered and liquid-disordered phases below their transition temperature (Tmix). Previous work in the lab has shown that Tmix is higher in GPMVs isolated from sparsely plated cells than those plated at a higher density (Gray et al. PLoS One 10(9):e0137741 (2015)). Since these cells are also contact inhibited, we hypothesize that differences in Tmix are related to their different growth rates. This previous study also found that Tmix is elevated in GPMVs isolated from cells preparing to undergo cell division compared to cells in other phases of the cell cycle. Based on these past results, we hypothesized that compounds which shift GPMV Tmix also affect the rate of cell growth when incubated with intact cells. To test this hypothesis, we incubated intact RBL-2H3 cells in n-alcohols and combinations of n-alcohols which we have previously shown to alter Tmix when added to isolated GPMVs (Machta et al. Biophys. J. 111(3):537-45 (2016)). We find that these treatments also alter cell growth as measured by counting cells present after 24h of incubation with compounds in complete media at 37°C. Specifically, fewer cells are counted in dishes containing n-alcohols that lower Tmix in GPMVs than that of a control, whereas an even greater number of cells are counted in dishes containing an n-alcohol that raises Tmix in GPMVs. In addition, we find that cells adapt their membrane composition to compensate for the effect of n-alcohols on GPMV Tmix when incubated with n-alcohols for 24h. Ongoing experiments are being conducted to illuminate the biochemical pathways underlying the observed changes in cell proliferation.