Sulfation by human lung fibroblasts: SO4(2-) and sulfur-containing amino acids as sources for macromolecular sulfation

• Published in: The American journal of physiology Vol. 260; no. 6 Pt 1; p. L450
• Main Authors: Elgavish, A, Meezan, E
• Format: Journal Article
• Language: English
• Published: United States 01.06.1991
• Subjects: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid - analogs & derivatives; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid - pharmacology; beta-Alanine - analogs & derivatives; beta-Alanine - pharmacology; Biological Transport - drug effects; Cell Line; Cysteine - drug effects; Cysteine - metabolism; Fibroblasts - drug effects; Fibroblasts - metabolism; Glucosamine - metabolism; Glycosaminoglycans - biosynthesis; Humans; Kinetics; Lung; Sulfates - metabolism; Taurine - pharmacology
• ISSN: 0002-9513
• DOI: 10.1152/ajplung.1991.260.6.l450

Studies were carried out in human lung fibroblasts (IMR-90) to investigate 1) the relative contribution of two extracellular pools, inorganic sulfate and sulfur-containing amino acids, to the intracellular fraction precipitable by trichloroacetic acid and 2) the possibility that the transport of these sulfur-containing substrates at the plasma membrane may be a limiting step for macromolecular sulfation. Our studies indicate that the ability to use SO4(2-) released by intracellular catabolism of the sulfur-containing amino acid L-cysteine differs from one cell system to another. In contrast to smooth muscle cells, in the human lung fibroblast, L-cysteine contributes significantly to the intercellular pool of SO4(2-) used for sulfation at extracellular [SO4(2-)] less than 100 microM. However, under physiological conditions with respect to SO4(2-) ([SO4(2-)]0 = 300 microM), L-cysteine does not contribute greater than 30% of the sulfate incorporated into the cellular fraction. Taurine (2-aminoethanesulfonic acid) inhibits SO4(2-) incorporation into the cell-associated macromolecular fraction. However, results suggest that the effect is not due to either SO4(2-) released by its catabolism or to an effect on SO4(2-) transport into the cell. The fact that the transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibits sulfate incorporation indicates that carrier-mediated sulfate transport at the cellular plasma membrane may be a limiting step for sulfate incorporation. In conclusion, under physiological conditions with respect to SO4(2-), inorganic sulfate is a major source of sulfate for sulfation in human lung fibroblasts and macromolecular sulfation may be limited by its transport into the cells.