scholarly journals Receptor-mediated endocytosis of retinol-binding protein by liver parenchymal cells: interference by radioactive iodination

1993 ◽  
Vol 291 (1) ◽  
pp. 187-191 ◽  
Author(s):  
L Malaba ◽  
G M Kindberg ◽  
K R Norum ◽  
T Berg ◽  
R Blomhoff
Keyword(s):  
Binding Protein ◽  
The Other ◽  
Retinol Binding Protein ◽  
Lag Phase ◽  
Steady Increase ◽  
Release Process ◽  
Liver Parenchymal ◽  
Cell Association ◽  
Higher Temperature ◽  
Parenchymal Cells

Retinol-binding protein (RBP) was iodinated directly by radio-iodine substitution on the tyrosyl residues by the sodium hypochlorite (NaOCl) or the Enzymobead (EB) methods, or indirectly by linkage of 125I-tyramine-cellobiose (TC) or 125I-N-succinimidyl-3-(4- hydroxyphenyl)propionic acid ester (SHPP) adduct on to free amino residues of RBP. Binding, uptake and degradation of iodinated RBP were studied in isolated rat and rabbit liver parenchymal cells. The amount of ligand bound to cells at 4 degrees C was dependent on the type of labelling, in that the 125I-TC ligand was bound to a lesser extent than NaClO-labelled 125I-RBP, EB-labelled 125I-RBP and 125I-SHPP-RBP. At 37 degrees C, the 125I-SHPP-RBP and the EB-labelled 125I-RBP became cell-associated more rapidly than the other two ligands. The higher cell association at 37 degrees C than at 4 degrees C suggests that internalization of the ligand occurred at the higher temperature. The degradation of the ligands was also different. The EB-labelled 125I-RBP, the 125I-TC-RBP and the 125I-SHPP-RBP showed an apparent lag phase before a steady increase in acid-soluble radioactivity was observed. Much less of EB-labelled 125I-RBP and 125I-TC-RBP were degraded (about 6%) than of the other two ligands (about 16%) after 120 min. About 50% of the acid-soluble radioactivity in these experiments could be accounted for by degradation in the medium, suggesting that about half of the degradation observed was intracellular. The present study therefore shows that the different labelling techniques yield varying estimates of the cellular handling of RBP. In addition, a rapid release of RBP was observed in experiments where cells were pulsed with radioactive RBP at 4 degrees C, washed and incubated further at 37 degrees C. Between 50% and 70% was released after 5 min of incubation. By increasing the temperature during the pulse to 37 degrees C, or by lowering the temperature during the chase to 4 degrees C, much less RBP was released from the cells. These data suggest that the release process represents recycling of internalized ligand from an early endosome.

Retinol uptake from retinol-binding protein (RBP) by liver parenchymal cells in vitro does not specifically depend on its binding to RBP

Biochemistry ◽  
1993 ◽  
Vol 32 (7) ◽  
pp. 1727-1733 ◽  
Author(s):  
Ariette M. Van Bennekum ◽  
William S. Blaner ◽  
Ingrid Seifert-Bock ◽  
Maria Moukides ◽  
Adriaan Brouwer ◽  
...  
Keyword(s):  
Binding Protein ◽  
Retinol Binding Protein ◽  
Liver Parenchymal ◽  
Parenchymal Cells

scholarly journals Serum retinol binding protein 4 is not decreased in congenital generalized lipodystrophy: a case series

2011 ◽  
Vol 55 (4) ◽  
pp. 279-283
Author(s):  
Amélio F. Godoy-Matos ◽  
Rodrigo O. Moreira ◽  
Renata MacDowell ◽  
Izidro Bendet
Keyword(s):  
Adipose Tissue ◽  
Binding Protein ◽  
Case Series ◽  
The Other ◽  
Retinol Binding Protein ◽  
Control Group ◽  
Serum Retinol ◽  
Retinol Binding Protein 4 ◽  
Congenital Generalized Lipodystrophy ◽  
Healthy Control

INTRODUCTION: Previous studies have suggested that Retinol Binding Protein 4 (RPB4), a protein produced by the adipose tissue, is associated with insulin resistance (IR). Congenital Generalized Lipodystrophy (CGL) is a rare disease characterized by IR and paucity of adipose tissue. Our objective was to determine RBP4 levels in patients with CGL. SUBJECTS AND METHODS: Six (6) patients with CGL and a healthy control group were selected to participate in the study. Anthropometric and biochemical variables were compared between groups. RESULTS: No difference was observed in RBP4 levels between the two groups (CGL 42.5 [12.5 - 127] vs. control 57.4 [15.9 - 165]; p = 0.78). On the other hand, leptin levels were significantly lower in CGL patients (CGL 0.65 [0.2 - 0.7] vs. control 10.9 [0.9 - 38.6]; p = 0.015). No correlation was found between RBP-4 and waist circunference (r = 0.18, p = 0.57), or BMI (r = 0.24, p = 0.45). CONCLUSION: RBP4 is not decreased in CGL. These results suggest that adipose tissue may not be the main source of RBP4.

The Application of Quantitative Stereology to the Study of Adenohypophyseal Cells

1976 ◽  
Vol 34 ◽  
pp. 124-125
Author(s):  
Max C. Poole ◽  
V.B. Mahesh ◽  
Allen Costoff
Keyword(s):  
Anterior Pituitary ◽  
Cell Types ◽  
The Other ◽  
Vaginal Smears ◽  
Prolactin Cells ◽  
Estrous Cycles ◽  
Liver Parenchymal ◽  
Quantitative Stereology ◽  
Parenchymal Cells ◽  
Different Cell Types

Quantitative stereology of liver parenchymal cells has previously been reported (1,2), but there have been few studies of morphometry applied to a heterogenous tissue (3). Due to the presence of several different cell types, it is difficult to study the synthesis and secretion of hormones in cells of the anterior pituitary by conventional biochemical means. In this study prolactin cells were analyzed using morphometry during different times of the rat estrous cycle, and were correlated with changing levels of prolactin in the serum and pituitary gland.Vaginal smears of 60 day old Holtzman rats were monitored through three estrous cycles, and only four day cycling rats were used. Groups of six animals were decapitated at 4 P.M., 6 P.M., 10 P.M. and 12 midnight of proestrus and one half of the pituitary was processed for electron microscopy and the other half for assay.

scholarly journals Immunocytochemical studies on the localization of plasma and of cellular retinol-binding proteins and of transthyretin (prealbumin) in rat liver and kidney.

1984 ◽  
Vol 98 (5) ◽  
pp. 1696-1704 ◽  
Author(s):  
M Kato ◽  
K Kato ◽  
D S Goodman
Keyword(s):  
Rat Liver ◽  
Binding Protein ◽  
Cell Types ◽  
Retinol Binding Protein ◽  
Specific Staining ◽  
Intense Staining ◽  
Cytoplasmic Staining ◽  
Liver And Kidney ◽  
Diffuse Cytoplasmic Staining ◽  
Parenchymal Cells

The immunocytochemical localization of cellular retinol-binding protein (CRBP), of plasma retinol-binding protein (RBP), and of plasma transthyretin (TTR) was studied in rat liver and kidney. The studies employed normal rats, retinol-deficient rats, and rats fed excess retinol. Antisera were prepared in rabbits against purified rat CRBP, RBP, and TTR. The primary antibodies and goat anti-rabbit IgG were purified by immunosorbent affinity chromatography, using the respective pure antigen coupled to Sepharose as the immunosorbent. This procedure effectively removed cross-reactive and heterophile antibodies, which permitted the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. CRBP was found to be localized in two cell types in the liver, the parenchymal cells and the fat-storing cells. Diffuse cytoplasmic staining for CRBP was seen in all the parenchymal cells. Much more intense staining for CRBP was seen in the fat-storing cells. The prominence of the CRBP-positive fat-storing cells changed markedly with vitamin A status. Thus, these cells were most prominent, and appeared most numerous, in liver from rats fed excess retinol. Both RBP and TTR were localized within liver parenchymal cells. The intensity of RBP staining increased markedly in retinol-deficient rat liver, consistent with previous biochemical observations. With the methods employed, specific staining for RBP or TTR was not seen in cells other than the parenchymal cells. In the kidney, all three proteins (CRBP, RBP, and TTR) were localized in the proximal convoluted tubules of the renal cortex. Staining for RBP was much more intense in normal kidney than in kidney from retinol-deficient rats. These findings reflect the fact that RBP in the tubules represents filtered and reabsorbed RBP. The pattern of specific staining for CRBP among the various tubules was very similar to that seen for RBP on adjacent, serial sections of kidney. The function of CRBP in the kidney is not known.

scholarly journals Effect of protein nutrition on the mRNA content of insulin-like growth factor-binding protein-1 in liver and kidney of rats

1993 ◽  
Vol 69 (1) ◽  
pp. 73-82 ◽  
Author(s):  
Asako Takenaka ◽  
Mitsuko Hirosawa ◽  
Masamichi Mori ◽  
Sanae Yamada ◽  
Yutaka Miura ◽  
...  
Keyword(s):  
Growth Factor ◽  
Binding Protein ◽  
Insulin Like Growth Factor ◽  
Casein Diet ◽  
Liver Parenchymal ◽  
Factor Binding ◽  
Mrna Content ◽  
Liver And Kidney ◽  
Protein Free Diet ◽  
Parenchymal Cells

Effect of quantity and nutritional quality of dietary proteins on the content of mRNA of insulin-like growth factor-binding protein-1 (IGFBP-1) was studied in rat liver and kidney. IGFBP-1 mRNA content per unit RNA increased in liver and kidney of rats fed on a protein-free diet and in those of fasted rats compared with that in the rats fed on a casein diet. When rats were given a gluten diet for 7 d, IGFBP-1 mRNA content in liver did not change significantly but that in kidney increased considerably compared with that in those organs of the rats fed on the casein diet. Because IGFBP-1 mRNA has been demonstrated both in liver parenchymal and non-parenchymal cells (Takenaka et al. 1991), the effect of the protein-free diet on these two types of cells has been studied. An increase in IGFBP-1 mRNA content under protein deprivation was observed in both liver parenchymal and non-parenchymal cells, suggesting that these two types of cells are regulated in a similar mode as far as IGFBP-1 mRNA content is concerned. The physiological and nutritional significance of the previously stated results on protein anabolism are discussed when considered together with our previous observations on the plasma concentrations of IGF-1 (Takahashi et al. 1990) and IGFBP (Umezawa et al. 1991) and insulin-like growth factor-1 mRNA content in liver (Miura et al. 1991).

scholarly journals Cytochemical localization of beta-NADPase in rat hepatocytes and Kupffer cells. Comparison with thiamine pyrophosphatase (TPPase).

1984 ◽  
Vol 32 (5) ◽  
pp. 541-546 ◽  
Author(s):  
S Angermüller ◽  
H D Fahimi
Keyword(s):  
Golgi Apparatus ◽  
Kupffer Cells ◽  
Intracellular Localization ◽  
Rat Hepatocytes ◽  
The Other ◽  
Cytochemical Localization ◽  
Liver Parenchymal ◽  
Thiamine Pyrophosphatase ◽  
The Difference ◽  
Parenchymal Cells

The intracellular localization of beta-NADPase in rat hepatocytes and Kupffer cells has been studied and compared with the pattern of TPPase in these cells. The reaction product for beta-NADPase is present in some but not all hepatocytes in two cisternae on the trans aspect of the Golgi apparatus. It is absent from the trans-most lamella and the GERL of hepatocytes. TPPase, on the other hand, is limited to the first Golgi cisterna on the trans aspect with sprinkles of reaction product in the second lamella. Considering that TPPase is a marker of the trans Golgi lamella and hepatocyte Golgi stacks contain usually 2-4 lamellae, our observations suggest that beta-NADPase is localized in the trans as well as in the intermediate Golgi lamellae of liver parenchymal cells. In Kupffer cells, the reaction product for both beta-NADPase and TPPase was found in some but not in all cells. The enzyme beta-NADPase was localized in the rigid lamella and the tubulovacuolar system of GERL. This pattern differed significantly from that for TPPase, which was found in 2-3 cisternae at the trans aspect of the Golgi complex in Kupffer cells. These observations demonstrate the difference in the localization of beta-NADPase in hepatocytes and Kupffer cells. Such differences should be taken into consideration in studies of Golgi fractions, when phosphatase reactions are used as specific markers of Golgi components.

EFFECT OF ARTIFICIAL PHOTOPERIODS ON PLASMA THYROXINE-BINDING PREALBUMIN AND RETINOL-BINDING PROTEIN IN JAPANESE QUAIL

1982 ◽  
Vol 92 (2) ◽  
pp. 163-173 ◽  
Author(s):  
D. J. HEAF ◽  
M. EL-SAYED ◽  
B. PHYTHIAN ◽  
J. CARROLL ◽  
J. GLOVER
Keyword(s):  
Japanese Quail ◽  
Binding Protein ◽  
Time Lag ◽  
The Other ◽  
Retinol Binding Protein ◽  
Molar Ratio ◽  
Cyclic Change ◽  
Minimum Level ◽  
Solar Lighting ◽  
Short Days

Variations in thyroxine-binding prealbumin (TBPA) and retinol-binding protein (RBP) concentrations in plasma were determined in Japanese quail subjected to a shortened solar lighting cycle lasting 4 months of real time. The concentration of TBPA varied inversely with the length of daily photoperiod up to 15 h (correlation coefficient r = −0·99) when a minimum level was reached of about 50% of that obtained under short days consisting of 8 h light: 16 h darkness (8L : 16D). A slight reversal in the concentration of TBPA occurred with photoperiods in excess of 16 h. The time-lag in response of the cyclic change in TBPA after the change in the lighting cycle was 8 days. The concentration of holoRBP, on the other hand, showed little change with photoperiods <15 h, but between 15 and 17·5 h it passed through peak values which were 24% and approximately 10% higher than the initial concentrations in female and male birds respectively. Total immunoreactive RBP concentrations in plasma peaked similarly in females but in males the apparent changes were not significant. The molar ratio of the two proteins (TBPA: RBP) which form a 1:1 complex in plasma also changed inversely with photoperiod from 1·6 on short (8L : 16D) to 0·6 on long (16L : 8D) days. When the ratio declined below 1·0 it was noted that rapid growth of the gonads took place and when this ratio returned to > 1·0 regression set in. The changes in plasma TBPA concentration were examined in Japanese quail subjected to sudden changes in photoperiod from short (8L : 16D) to long (20L : 4D) days and vice versa. In the group of birds transferred from short to long days the plasma level declined significantly (P<0·05) within 3 days, whereas birds changed from long to short days were more refractory in that a significant increase was seen only after 30 days. The synthesis of TBPA in liver is closely controlled by photoperiod and it seems that this protein plays an important role in the peripheral distribution of thyroxine and perhaps also influences the cyclical supply of retinol to the gonads.

The localization of retinol-binding protein in rat liver by immunofluorescence microscopy

1975 ◽  
Vol 19 (2) ◽  
pp. 379-394
Author(s):  
A.R. Poole ◽  
J.T. Dingle ◽  
A.K. Mallia ◽  
D.S. Goodman
Keyword(s):  
Vitamin A ◽  
Rat Liver ◽  
Immunofluorescence Microscopy ◽  
Binding Protein ◽  
Normal Liver ◽  
Retinol Binding Protein ◽  
Cytoplasmic Staining ◽  
Cytoplasmic Vesicles ◽  
Tissue Antigens ◽  
Parenchymal Cells

The localization of immunoreactive retinol-binding protein (RBP) in rat liver was studied by immunofluorescence microscopy. The study employed specific antisera to rat RBP prepared in a rabbit and in a sheep. The indirect, two-stage method of localizing tissue antigens was employed, and livers of both normal and vitamin A-deficient rats were examined. Fab' fragments of immunoglobulins were used, to minimize non-specific labelling of the frozen sections of liver. With these techniques, the specific immune staining of RBP was observed within liver parenchymal cells. This staining appeared as both particulate and diffuse within the cytoplasm of the parenchymal cells, and was not concentrated within one region of the liver cell or lobule. Staining for RBP was not observed in nuclei or in cells other than parenchymal cells. Similar particulate and diffuse immune staining for RBP was observed in liver sections from both vitamin A-deficient and normal rats. More intense immune staining appeared to be present in the sections of vitamin A-deficient animals, in good correlation with the expected higher levels of RBP in deficient as compared to normal liver. When liver sections were exposed to an antiserum to rat albumin, instead of one to rat RBP, immune cytoplasmic staining was observed which was entirely of a diffuse nature, and did not appear particulate or granular. The findings suggest that RBP, unlike albumin, is localized in part within cytoplasmic vesicles or granules which are large enough to be detected with immunofluorescence, and which are present in livers of both normal and vitamin A-deficient animals. The nature of these putative RBP-containing particles remains to be explored.

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