A multicompartmental model of fluid-phase endocytosis in rabbit liver parenchymal cells

R. Blomhoff, M. S. Nenseter, Michael Henry Green, T. Berg

Research output: Contribution to journalArticle

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Abstract

Fluid-phase endocytosis was studied in isolated rabbit liver parenchymal cells by using 125I-poly(vinylpyrrolidone) (PVP) as a marker. First, uptake of 125I-PVP by cells was determined. Also, cells were loaded with 125I-PVP for 20, 60 and 120 min, and release of marker was monitored for 120-220 min. Then we used the Simulation, Analysis and Modeling (SAAM) computer program and the technique of model-based compartmental analysis to develop a mechanistic model for fluid-phase endocytosis in these cells. To fit all data simultaneously, a model with three cellular compartments and one extracellular compartment was required. The three kinetically distinct cellular compartments are interpreted to represent (1) early endosomes, (2) a prelysosomal compartment equivalent to the compartment for uncoupling of receptor and ligand (CURL) and/or multivesicular bodies (MVB), and (3) lysosomes. The model predicts that approx. 80% of the internalized 125I-PVP was recycled to the medium from the early-endosome compartment. The apparent first-order rate constant for this recycling was 0.094 min-1, thus indicating that an average 125I-PVP molecule is recycled in 11 min. The model also predicts that recycling to the medium occurs from all three intracellular compartments. From the prelysosomal compartment, 40% of the 125I-PVP molecules are predicted to recycle to the medium and 60% are transferred to the lysosomal compartment. The average time for recycling from the prelysosomal compartment to the medium was estimated to be 66 min. For 125I-PVP in the lysosomal compartment, 0.3%/min was transferred back to the medium. These results, and the model developed to interpret the data, predict that there is extensive recycling of material endocytosed by fluid-phase endocytosis to the extracellular environment in rabbit liver parenchymal cells.

Original languageEnglish (US)
Pages (from-to)605-610
Number of pages6
JournalBiochemical Journal
Volume262
Issue number2
DOIs
StatePublished - Jan 1 1989

Fingerprint

Endocytosis
Liver
Recycling
Rabbits
Fluids
Endosomes
Multivesicular Bodies
Povidone
Lysosomes
Molecules
Software
Computer program listings
Rate constants
Ligands

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Blomhoff, R. ; Nenseter, M. S. ; Green, Michael Henry ; Berg, T. / A multicompartmental model of fluid-phase endocytosis in rabbit liver parenchymal cells. In: Biochemical Journal. 1989 ; Vol. 262, No. 2. pp. 605-610.
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abstract = "Fluid-phase endocytosis was studied in isolated rabbit liver parenchymal cells by using 125I-poly(vinylpyrrolidone) (PVP) as a marker. First, uptake of 125I-PVP by cells was determined. Also, cells were loaded with 125I-PVP for 20, 60 and 120 min, and release of marker was monitored for 120-220 min. Then we used the Simulation, Analysis and Modeling (SAAM) computer program and the technique of model-based compartmental analysis to develop a mechanistic model for fluid-phase endocytosis in these cells. To fit all data simultaneously, a model with three cellular compartments and one extracellular compartment was required. The three kinetically distinct cellular compartments are interpreted to represent (1) early endosomes, (2) a prelysosomal compartment equivalent to the compartment for uncoupling of receptor and ligand (CURL) and/or multivesicular bodies (MVB), and (3) lysosomes. The model predicts that approx. 80{\%} of the internalized 125I-PVP was recycled to the medium from the early-endosome compartment. The apparent first-order rate constant for this recycling was 0.094 min-1, thus indicating that an average 125I-PVP molecule is recycled in 11 min. The model also predicts that recycling to the medium occurs from all three intracellular compartments. From the prelysosomal compartment, 40{\%} of the 125I-PVP molecules are predicted to recycle to the medium and 60{\%} are transferred to the lysosomal compartment. The average time for recycling from the prelysosomal compartment to the medium was estimated to be 66 min. For 125I-PVP in the lysosomal compartment, 0.3{\%}/min was transferred back to the medium. These results, and the model developed to interpret the data, predict that there is extensive recycling of material endocytosed by fluid-phase endocytosis to the extracellular environment in rabbit liver parenchymal cells.",
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A multicompartmental model of fluid-phase endocytosis in rabbit liver parenchymal cells. / Blomhoff, R.; Nenseter, M. S.; Green, Michael Henry; Berg, T.

In: Biochemical Journal, Vol. 262, No. 2, 01.01.1989, p. 605-610.

Research output: Contribution to journalArticle

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