The nuclear ceramide/diacylglycerol balance depends on the physiological state of thyroid cells and changes during UV-C radiation-induced apoptosis.
Intranuclear lipid metabolism modifications in relation to cell proliferation and/or apoptosis were demonstrated in hepatocytes. The aim of this study was to establish whether nuclear lipid metabolites influence cell function in different experimental models using a rat thyroid cell line (FRTL-5) treated with UV-C radiation. After UV-C irradiation cells proliferate and undergo apoptosis in the presence of thyrotropin, are quiescent and resistant to radiation-induced apoptosis in its absence and finally are proapoptotic for nutrition withdrawal. In nuclei purified from proliferating cells, irradiation stimulates neutral-sphingomyelinase activity and inhibits sphingomyelin-synthase, phosphatidylcholine-specific phospholipase C and phosphatidylinositol-specific phospholipase C activity with a consequent increase in the ceramide/diacylglycerol ratio. This effect is marked in proapoptotic cell nuclei and low in quiescent cell nuclei. In conclusion, UV-C radiation induces apoptosis, modifying nuclear lipid metabolism in relation to the physiological state of cells.
Albi
E
E
Department of Clinical and Experimental Medicine, Physiopathology Section, Policlinico Monteluce, Via Brunamonti, 06100 Perugia, Italy. ealbi@unipg.it
Cataldi
S
S
Rossi
G
G
Viola Magni
M
M
Toller
M
M
Casani
S
S
Perrella
G
G
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D008954:Models, Biological; D051381:Rats; D013961:Thyroid Gland / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism; D017855:Transferases (Other Substituted Phosphate Groups) / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014466:Ultraviolet Rays
D002518:Ceramides; D004075:Diglycerides; D008055:Lipids; D013972:Thyrotropin; D017855:Transferases (Other Substituted Phosphate Groups); C488077:reverse sphingomyelin-synthase, rat; D010738:Type C Phospholipases