Characterization of Cellular DGK-θ

摘要: In this report we have summarized the data regarding regulation of DGK-θ by two phospholipids: PtdSer and PtdOH. Our previous has shown that stimulation quiescent fibroblasts with a potent mitogen (α-thrombin) leads to an increase in nuclear localized (Bregoli, L., Baldassare, J. J., Raben, D. M., 2001; Bregoli, Tu-Sekine, B., 2002), as been seen neuronal cells (Tabellini, G., Bortul, R., Santi, S., Riccio, Baldini, Cappellini, A.et al., 2003; Tabellini, Billi, A. Fala, F., A., Evagelisti, C., Manzoli, L.et 2004). Furthermore, these studies demonstrated is actually matrix 2002; 2003). As also previously PtdOH modulate activity (Tu-Sekine, Ostroski, 2006; 2007), examined phospholipid composition well intact nuclei non-nuclear membranes. This analysis revealed there are phospholipids “matrix” lipids largely resembles those other The physical form localization matrix-associated not established, though nearly identical percent membranes lend credence hypothesis at least some internal lipid derived from invaginations cellular through interior known tubules (Fricker, Hollinshead, White, N., Vaux, D., 1997; Lee, R. K., Lui, P. P., Ngan, E. Suen, Y. Chan, F.et 2006). An important finding resulting envelope enriched relative membranes, over-expression reduces both PtdEth levels envelope. While mechanism behind fluctuations unknown, consistent DGK-regulated phosphatidylcholine-dependent phosphatidylserine synthase (PSS-1) (EC 2.7.8.8) synthesis mammalian proceeds headgroup exchange PtdCho or PtdEth, catalyzed PSS-1 PSS-2, respectively. Interestingly, decrease membrane mirrors effects observed CHO-K1 mutant cell lines M.6.1.1 PSA-3, which be deficient (Vance, Steenbergen, 2005). very little information on PSS enzymes, phosphorylation regulate serine activities rat brain (Kanfer, McCartney, Hattori, H., 1988), regulates exit PKC-α nucleus (see Regulation PKC-α). To our knowledge, currently no reported study phosphatidylyserine synthases. One notable fluctuation expression plasmalogen NNM matrix. majority conducted agree almost complete dependence classical CDP-ethanolamine pathway provide for precursor synthesized peroxisome, several utilizing radiolabeled approximately 20-30% plasmalogen-PtdEth can models (Yorek, M. Rosario, T., Dudley, Spector, 1985; Xu, Z. Byers, Palmer, F. Spence, W., Cook, H. 1991). Whether PtdSer-derived present expressing evident presented here, one potential flux could At juncture only speculate cause perturbations, further work required support impacts metabolism. The physiological role remained mystery. It long recognized obvious DGKs its DAG substrate thereby modulating DAG-sensitive proteins like such many PKCs (Merida, I., Avila-Flores, Merino, E., 2008). notion suppression DGK-θ, either RhoA dominant-negative construct sustained (Figure 2). In addition PtdOH, here modulated Class I PI 3-kinase. effect various inhibitors lysates over-expressing isoform. often use pharmacologic determine selected enzymes signaling pathways. approach useful comparative analyses, pertaining DGK-θ. We found well-established PI-PLC inhibitor, {"type":"entrez-nucleotide","attrs":{"text":"U73122","term_id":"4098075","term_text":"U73122"}}U73122, but inactive analog {"type":"entrez-nucleotide","attrs":{"text":"U73343","term_id":"1688125","term_text":"U73343"}}U73343, competitively inhibits isoform respect diacylglycerol (DAG) substrate. These indicate designed examine using inhibitor should interpreted caution. Major Topics Diacylglycerol kinase DGKtheta Lipids Enzymology Diacylglycerol Phosphatidylserin Phophatidic acid Signal Transduction Kinases Enzymes Mixed Micelles Competitive Inhibition PI 3-Kinase DGK-θ RhoA ​ TABLE 1 Phospholipid embryonic fibroblasts Acknowledgements This was supported Grant GM059251 National Institutes Health (D.M.R.).