The decreased synthesis of chondroitin sulfate-containing extracellular proteoglycans by SV40 transformed Balb/c 3T3 cells |
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Authors: | Michael Klagsbrun |
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Institution: | Department of Surgery, Children''s Hospital Medical Center and the Harvard Medical School, Boston, Mass. 02115, U.S.A. |
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Abstract: | Balb/c 3T3 cells synthesize 5–10 times more 35SO42?-labeled extracellular proteoglycan per cell than do Balb/c 3T3 cells transformed by SV40 (SV3T3). The extracellular 35SO42?-labeled proteoglycans of the Balb/c 3T3 and SV3T3 cells differ markedly in their acid mucopolysaccharide composition. Extracellular Balb/c 3T3 proteoglycans contain about 70–80% chondroitin sulfate, most of which is chondroitin 4-sulfate, and small amounts of heparan sulfate and/or heparin. On the other hand, extracellular SV3T3 proteoglycans contain 65–75% heparan sulfate and/or heparin and less than 15% chondroitin sulfate. Analysis of extracellular 35SO42?-labeled proteoglycan by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that Balb/c 3T3 alone synthesizes a class of proteoglycans capable of migrating in a 10% separating gel. This class of proteoglycans, designated as fraction C, accounts for up to 45% of the total extracellular Balb/c 3T3 35SO42?-labeled proteoglycans and contains chondroitin sulfate exclusively. It is altogether absent in the extracellular SV3T3 proteoglycans. The absence of this and other classes of chondroitin sulfate-containing proteoglycans can account for the 5–10-fold decreased synthesis of 35SO42?-labeled proteoglycans by SV3T3 cells when compared to Balb/c 3T3 cells. |
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