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Title: Proteoglycan biosynthesis in murine monocytic leukemic (M1) cells before and after differentiation

Journal Article · · Journal of Biological Chemistry; (USA)
OSTI ID:5607776
; ; ;  [1]
  1. National Institute of Dental Research, Bethesda, MD (USA)

Murine monocytic leukemic (M1) cells were cultured in the presence of ({sup 3}H)glucosamine and ({sup 35}S)sulfate. Labeled proteoglycans were purified by anion exchange chromatography and characterized by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in combination with chemical and enzymatic degradation. M1 cells synthesize a single predominant species of proteoglycan which distributes almost equally between the cell and medium after 17 h labeling. The cell-associated proteoglycan has an overall size of about 135 kDa and contains three to five chondroitin sulfate chains (28-31 kDa each) attached to a chondroitinase-generated core protein of 28 kDa. The synthesis and subsequent secretion of this proteoglycan was enhanced 4-5-fold in cells induced to differentiate into macrophages. This was not a phenomenon of arrest in the G0/G1 stage of the cell cycle, since density inhibited undifferentiated cells arrested at this stage did not increase proteoglycan synthesis. The chondroitin sulfate chains contained exclusively chondroitin 4- and 6-sulfate; however, the ratio of these two disaccharides differed between the medium- and cell-associated proteoglycans, and changed during progression of the cells into a fully differentiated phenotype. Pulse-chase kinetics indicate the presence of two distinct pools of proteoglycan; one that is secreted very rapidly from the cell after a approximately 1-h lag, and a second pool that is turned over in the cell with a half-time of approximately 3.5 h. Subtle differences in the glycosylation patterns of the medium- and cell-associated species are consistent with synthesis of two pools. Papain digestion suggests that the chondroitin sulfate chains are clustered on a small protease resistant peptide. The data suggest that this proteoglycan is similar to the serglycin proteoglycan family.

OSTI ID:
5607776
Journal Information:
Journal of Biological Chemistry; (USA), Vol. 264:22; ISSN 0021-9258
Country of Publication:
United States
Language:
English

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