0000000001333633
AUTHOR
Taverna, Simona
nCDase and SphK-1 localization in vesicles shed by tumour cells and their biological roles.
Sphingolipid metabolism is a dynamic process resulting in the formation of a number of bioactive metabolites including ceramide, ceramide-1-phosphate, sphingosine e sphingosine-1-phosphate (S1P). (Pyne and Pyne; Biochem. J. 2000; 349:385-402). Following sphingomyelinase activation, sphingomyelin is hydrolyzed to ceramide, which is considered to be an inducer of cell growth arrest, differentiation and apoptosis. (Hannun et. al 1996; Science: 274:1855-1859). Ceramidase catalyzes the deacylation of ceramide to produce a free fatty acid and sphingosine. The enzyme sphingosine kinase (SphK) catalyzes the formation of S1P from sphingosine and ATP (Olivera et al. J.Biol.Chem. 1998; 273:12576- 1258…
Shed vesicles are involved in the release of some leaderless proteins.
Most proteins destined for secretion in the extracellular matrix are characterized by the presence of N-terminal signal peptides which direct their translocation into the endoplasmic reticulum, they are subsequently transferred to the Golgi apparatus and then secreted in the extracellular space. A growing number of secreted proteins, are being identified which, however, lack signal peptides allowing their entrance into the endoplasmic reticulum. They include the inflammatory cytokine interleukin 1b, galactins, macrophage migration inhibitory factor (MIF), acid and basic fibroblast growth factors (FGF-1, FGF-2) and Sphingosine kinase1(SphK-1). These proteins are secreted from the cell by unc…