Effect of C2 ceramide on the inositol phospholipid metabolism (uptake of 32P, 3H-serine and 3H-palmitic acid) and apoptosis-related morphological changes in Tetrahymena.
Sphingomyelin metabolites have significant role in the regulation of many life processes of mammalian cells. In the present experiments the influence of phospholipid turnover and apoptosis related morphologic signs by one of this metabolite, C2 ceramide was studied, and compared to the control, untreated cells, in the unicellular Tetrahymena. The incorporation of phospholipid head group components (serine, phosphorus) show a clear time-dependence; while the incorporation of fatty acid component (palmitic acid) is very fast: no significant alterations were found between 5- and 60-min incubations. C2 ceramide treatment didn't alter 3H-palmitic acid incorporation into phospholipids, however 3H-serine incorporation was mainly inhibited. The amount of total incorporated 32P was also decreased, on the other hand the lover concentration C2 ceramide (10 microM) elevated the synthesis of inositol phospholipids. The higher concentration of C2 ceramide (50 microM) had inhibitory effect on the synthesis of each phospholipids examined. This means that in the presence of the C2 ceramide the synthesis, recovery and turnover of phospholipids, participating in signal transduction, are altered. However these observations were based the uptake of labeled phospholipid precursors, which gives information on the dynamics of the process, without using lipid mass measurements. C2 ceramide also caused the rounding off the cells, DNA degradation and nuclear condensation. These latter observations point to morphological signs of apoptosis. The results call attention to the role of sphingomyelin metabolites on signalization of unicellulars, to the cross-talk between the inositol phospholipids and sphingomyelin metabolites, and the role of these molecules in the apoptotic processes at a low evolutionary level.
Kovács
P
P
Department of Genetics, Cell and Immunobiology, Semmelweis University of Medicine, Budapest, Hungary.
Hegyesi
H
H
Köhidai
L
L
Nemes
P
P
Csaba
G
G
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002843:Chromatin / Q000378:metabolism; D053938:DNA Fragmentation; D007700:Kinetics; D019308:Palmitic Acid / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010761:Phosphorus Radioisotopes / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013768:Tetrahymena / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D014316:Tritium
D002843:Chromatin; C064769:N-acetylsphingosine; D010716:Phosphatidylinositols; D010761:Phosphorus Radioisotopes; D014316:Tritium; D019308:Palmitic Acid; D012694:Serine; D013110:Sphingosine