Human glomerular epithelial cell proteoglycans.
Proteoglycans synthesized by cultures of human glomerular epithelial cells have been isolated and characterized. Three types of heparan sulfate were detected. Heparan sulfate proteoglycan I (HSPG-I; Kav 6B 0.04) was found in the cell layer and medium and accounted for 12% of the total proteoglycans synthesized. HSPG-II (Kav 6B 0.25) accounted for 18% of the proteoglycans and was located in the medium and cell layer. A third population (9% of the proteoglycan population), heparan sulfate glycosaminoglycan (HS-GAG; Kav 6B 0.4-0.8), had properties consistent with single glycosaminoglycan chains or their fragments and was found only in the cell layer. HSPG-I and HSPG-II from the cell layer had hydrophobic properties; they were released from the cell layer by mild trypsin treatment. HS-GAG lacked these properties, consisted of low-molecular-mass heparan sulfate oligosaccharides, and were intracellular. HSPG-I and -II released to the medium lacked hydrophobic properties. The cells also produced three distinct types of chondroitin sulfates. The major species, chondroitin sulfate proteoglycan I (CSPG-I) eluted in the excluded volume of a Sepharose CL-6B column, accounted for 30% of the proteoglycans detected, and was found in both the cell layer and medium. Cell layer CSPG-I bound to octyl-Sepharose. It was released from the cell layer by mild trypsin treatment. CSPG-II (Kav 6B 0.1-0.23) accounted for 10% of the total 35S-labeled macromolecules and was found predominantly in the culture medium. A small amount of CS-GAG (Kav 6B 0.25-0.6) is present in the cell extract and like HS-GAG is intracellular. Pulse-chase experiments indicated that HSPG-I and -II and CSPG-I and -II are lost from the cell layer either by direct release into the medium or by internalization where they are metabolized to single glycosaminoglycan chains and subsequently to inorganic sulfate.
Thomas
G J
GJ
Department of Medicine, University of Wales College of Medicine, Royal Infirmary, Cardiff, United Kingdom.
Jenner
L
L
Mason
R M
RM
Davies
M
M
D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004848:Epithelium / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007678:Kidney Glomerulus / Q000378:metabolism*; D007700:Kinetics; D011509:Proteoglycans / Q000032:analysis* / Q000096:biosynthesis / Q000302:isolation & purification; D011865:Radioisotope Dilution Technique; D013431:Sulfates / Q000378:metabolism; D013462:Sulfur Radioisotopes
D000911:Antibodies, Monoclonal; D011509:Proteoglycans; D013431:Sulfates; D013462:Sulfur Radioisotopes