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Titolo:
EFFECT OF LONG-TERM TREATMENT OF 3T3-L1 ADIPOCYTES WITH CHLORATE ON THE SYNTHESIS, GLYCOSYLATION, INTRACELLULAR-TRANSPORT AND SECRETION OF LIPOPROTEIN-LIPASE
Autore:
MASUNO H; SAKAYAMA K; OKUDA H;
Indirizzi:
EHIME COLL HLTH SCI,DEPT MED LAB TECHNOL TOBE EHIME 79121 JAPAN EHIME UNIV,SCH MED,DEPT ORTHOPED SURG SHIGENOBU EHIME 79102 JAPAN EHIME UNIV,SCH MED,DEPT BIOCHEM MED SHIGENOBU EHIME 79102 JAPAN
Titolo Testata:
Biochemical journal
, volume: 329, anno: 1998,
parte:, 3
pagine: 461 - 468
SICI:
0264-6021(1998)329:<461:EOLTO3>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
CULTURED BROWN ADIPOCYTES; BREFELDIN-A; OLIGOSACCHARIDE CHAINS; RADIATION INACTIVATION; ENDOPLASMIC-RETICULUM; CATALYTIC ACTIVITY; GOLGI PROTEINS; CELLS; BIOSYNTHESIS; CASTANOSPERMINE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
H. Masuno et al., "EFFECT OF LONG-TERM TREATMENT OF 3T3-L1 ADIPOCYTES WITH CHLORATE ON THE SYNTHESIS, GLYCOSYLATION, INTRACELLULAR-TRANSPORT AND SECRETION OF LIPOPROTEIN-LIPASE", Biochemical journal, 329, 1998, pp. 461-468

Abstract

Lipoprotein lipase (LPL) is synthesized and glycosylated in the endoplasmic reticulum (ER), transported through the Golgi to the cell surface, and finally secreted. To examine the role of heparan sulphate proteoglycans (HSPG) in the synthesis, activity, intracellular transport and secretion of LPL, 3T3-L1 adipocytes were cultured for 7 days in thepresence of 20 mM chlorate, an inhibitor of sulphation of HSPG. Treatment of cells with 20 mM chlorate for 7 days caused a 55 % decrease inLPL activity in the intracellular compartment and a 79 % decrease in the cell-surface compartment. The synthetic rate of LPL in chlorate-treated cells was identical with that in control cells as determined by biosynthetic labelling. The study with endoglycosidase H (endo H) showed that the treatment with chlorate increased the proportion of LPL subunits which were totally endo H-sensitive. The study with a heparin-Sepharose column showed that 3T3-L1 adipocytes contained three forms ofLPL. The first form, accounting for 35 % of the LPL, did not bind to the heparin-Sepharose column and had little or no activity; the secondform, accounting for 32 %, bound to the column and was eluted with 0.4-0.75 M NaCl but had no activity; the third form, accounting for 33 %, bound to the column and was eluted with 0.8-1.2 M NaCl and had activity. In chlorate-treated cells, the first form accounted for 66 % of the LPL, the second form 15 % and the third form 19 %. When cells were incubated for 1 h with brefeldin A, which translocates Golgi proteins to the ER [J. Lippincott-Schwartz, L. C. Yuan, J. S. Banifacino and R. D. Klausner (1989) Cell 56, 801-813; J. Lippincott-Schwartz, J. Glickman, J. E. Donaldson, J. Robbins, T. E. Kreis, K. B. Seamen, M. P. Sheetz and R. D. Klausner (1991) J. Cell Biol. 112, 567-577], the chlorate-induced decrease in cellular LPL activity was restored. These findings indicate that LPL synthesized in chlorate-treated cells can be processed to be fully active, but chlorate-treated cells are unable to transport LPL to the Golgi and accumulate inactive LPL with a lower affinity for heparin in the ER. The treatment with chlorate decreased the proportion of LPL subunits that were endo H-resistant, indicating that the processing of oligosaccharide chains of LPL in the trans-Golgi wasimpaired in chlorate-treated cells. The amount of S-35-labelled LPL secreted by chlorate-treated cells was identical with that secreted by control cells, whereas the level of LPL activity in the medium of chlorate-treated cells was 25 % of that in the medium of control cells, indicating that most of the LPL secreted by chlorate-treated cells was inactive.

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Documento generato il 30/09/20 alle ore 04:47:25