tailieunhanh - Báo cáo khoa học: Lipid droplet and milk lipid globule membrane associated placental protein 17b (PP17b) is involved in apoptotic and differentiation processes of human epithelial cervical carcinoma cells

The intracellular role of placental protein 17b (PP17b)/ TIP47has been controversial, because it is considered tobe a protein required for mannose 6-phosphate receptor trans-port from endosome totrans-Golgi as well as a neutral lipid similaritybetween theamino acid sequences of PP17 variants, adipophilin and perilipins, andbetween their gene structures indicate that PP17baswell as other alternatively spliced PP17 variants belong to the lipid storage droplet protein family, containing also some differentiation factors | Eur. J. Biochem. 270 1176-1188 2003 FEBS 2003 doi Lipid droplet and milk lipid globule membrane associated placental protein 17b PP17b is involved in apoptotic and differentiation processes of human epithelial cervical carcinoma cells Nandor G. Than1 2. Balazs Sumegi2 Szabolcs Bellvei2. Timea Berki3 Gvorgv Szekeres4. Tamas Janakv5. . Andras Szigeti2 Hans Bohn6 and Gabor N. Than7 1 First Department of Obstetrics and Gynecology Semmelweis University Budapest Hungary Departments of 2Biochemistry and Medical Chemistry Immunology and Biotechnology and Obstetrics and Gynecology University of Pecs Hungary 4Histopathology Ltd Pecs Hungary 5Department of Medical Chemistry University of Szeged Szeged Hungary 6Behringwerke AG MarburgỊLahn Germany The intracellular role of placental protein 17b PP17b TIP47 has been controversial because it is considered to be a protein required for mannose 6-phosphate receptor transport from endosome to trans-Golgi as well as a neutral lipid droplet-associated protein. The similarity between the amino acid sequences of PP17 variants adipophilin and perilipins and between their gene structures indicate that PP17b as well as other alternatively spliced PP17 variants belong to the lipid storage droplet protein family containing also some differentiation factors. Using a specific antibody PP17b was detected in lipid droplet fractions and co-localized with neutral lipid droplets stained by Nile red and fluorescently labelled PP17 antibody in HeLa cells with confocal microscopy. PP17b was also detected in milk associated to milk lipid globule membranes. Cytostatic agents induced apoptosis and PP17b synthesis in HeLa cells which was significantly inhibited by protein kinase C PKC inhibitor indicating the involvement of NF-kB and AP-1 transcription factors in this process while protein kinase A PKA inhibitor had only a modest inhibitory effect. Cell differentiation induced by dibutyryl cyclic AMP or phorbol myristate .