scholarly journals Effects of nonketotic streptozotocin diabetes on apolipoprotein B synthesis and secretion by primary cultures of rat hepatocytes.

1988 ◽  
Vol 82 (1) ◽  
pp. 37-43 ◽  
Author(s):  
J D Sparks ◽  
C E Sparks ◽  
M Bolognino ◽  
A M Roncone ◽  
T K Jackson ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Primary Cultures ◽  
Streptozotocin Diabetes ◽  
Rat Hepatocytes

scholarly journals Synchronized synthesis and intracellular transport of serum albumin and apolipoprotein B in cultured rat hepatocytes as studied by double immunofluorescence.

1986 ◽  
Vol 34 (9) ◽  
pp. 1223-1230 ◽  
Author(s):  
G A Keller ◽  
C Glass ◽  
D Louvard ◽  
D Steinberg ◽  
S J Singer
Keyword(s):  
Serum Albumin ◽  
Apolipoprotein B ◽  
Intracellular Transport ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Cell System ◽  
Secretory Proteins ◽  
Transport Pathway ◽  
Apo B ◽  
Normal Rat

Synthesis and intracellular transport of two secretory proteins, serum albumin (SA) and apolipoprotein B (apo B) have been synchronized in primary cultures of normal rat hepatocytes to make possible immunocytochemical study of the transport pathway. Under appropriate conditions of cycloheximide treatment, synthesis of new protein was inhibited and, by double immunofluorescent labeling, the cells were found to be largely depleted of the SA and apo B previously synthesized. Re-initiation of protein synthesis led to sequential appearance of SA and apo B, first in the endoplasmic reticulum, then in the Golgi complex, and finally at the cell surface. These results indicate that it should be feasible to use this cell system for high-resolution investigation of the sequence of structures involved in intracellular transport of SA and apo B by corresponding immunolabeling experiments as observed by electron microscopy.

scholarly journals Insulin-mediated inhibition of apolipoprotein B secretion requires an intracellular trafficking event and phosphatidylinositol 3-kinase activation: studies with brefeldin A and wortmannin in primary cultures of rat hepatocytes

1996 ◽  
Vol 313 (2) ◽  
pp. 567-574 ◽  
Author(s):  
Janet D. SPARKS ◽  
Thuy L. PHUNG ◽  
Mary BOLOGNINO ◽  
Charles E. SPARKS
Keyword(s):  
Apolipoprotein B ◽  
Enzyme Inhibitor ◽  
Primary Cultures ◽  
Brefeldin A ◽  
Rat Hepatocytes ◽  
Phosphatidylinositol 3 Kinase ◽  
Apo B ◽  
Insulin Effect ◽  
Insulin Inhibition ◽  
Phosphatidylinositol 3

Insulin inhibition of the secretion of apolipoprotein B (apo B) was studied in primary cultures of rat hepatocytes by using brefeldin A (BFA), an inhibitor of protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus, and by using the phosphatidylinositol 3-kinase (PI 3-K) inhibitor wortmannin. Incubation of hepatocytes with BFA (10 μg/ml) for 1 h inhibited the subsequent secretion of apo B, albumin and transferrin for up to 3 h. BFA treatment resulted in the time-dependent accumulation in cells of [14C]leucine-labelled proteins and apo B. Under conditions where insulin decreased total apo B (cell plus secreted), BFA blocked the insulin-dependent effect. These results suggest that export of apo B from the ER is a prerequisite for the observed insulin effect. Treatment of hepatocytes with wortmannin for 20 min abolished insulin inhibition of apo B secretion, suggesting that the insulin effect on the apo B pathway involves activation of PI 3-K. Enzyme inhibitor studies indicate that chymostatin and (+)-(2S,3S)-3-[(S)-methyl-1-(3-m e t h y l b u t y l c a r b a m o y l) - b u t y l c a r b a m o y l] - 2-oxiranecarboxylate (E-64-c) partially block insulin effects on apo B compared with leupeptin, which had no discernible effect. The cell-permeable derivative of E-64-c, EST, and N-Ac-Leu-Leu-norleucinal (ALLN) were most effective in blocking insulin effects on apo B. These results suggest that insulin action on apo B in primary rat hepatocytes involves (1) vesicular movement of apo B from the ER; (2) activation of PI 3-K and (3) a cellular protease that is either a cysteine- or calcium-activated neutral protease.

Insulin effects on apolipoprotein B lipoprotein synthesis and secretion by primary cultures of rat hepatocytes

Metabolism ◽  
1986 ◽  
Vol 35 (12) ◽  
pp. 1128-1136 ◽  
Author(s):  
Charles E. Sparks ◽  
Janet D. Sparks ◽  
Mary Bolognino ◽  
Arthur Salhanick ◽  
Paul S. Strumph ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Lipoprotein Synthesis
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