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- Lohmander, Stefan, et al.
(författare)
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Proteoglycans of mineralizing rib and epiphyseal cartilage
- 1975
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Ingår i: Biochimica et Biophysica Acta. General Subjects. - : Elsevier BV. - 0304-4165. ; 404:1, s. 93-109
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Tidskriftsartikel (refereegranskat)abstract
- Rib cartilage from growing guinea pigs and epiphyseal cartilage from Beagle puppie were separated into three fractions, representing non-mineralized, low mineralized, and high mineralized, tissue, by centrifuging finely ground material in acetone/bromoform density gradients. Following extraction under dissociative conditions, the proteoglycans were fractionated by density gradient ultracentrifugation under associative and dissociative conditions. With the onset of mineralization, the cartilage lost approximately half its content of proteoglycans. The proteoglycans remaining in the calcified cartilage differed in composition and in size from those of nonmineralized tissue. With the increased mineral content of the tissues the ratios of protein to polysaccharide, of chondroitin sulfate to keratan sulfate, and of 4-sulfated to 6-sulfated chondroitin sulfate increased in the proteoglycan fraction. Furthermore, gel chromatograms indicated decreased proportions of very high molecular weight proteoglycans, in mineralized tissue.
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- Lohmander, S., et al.
(författare)
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Secretion of proteoglycans by chondrocytes. Influence of colchicine, cytochalasin B, and β-d-xyloside
- 1979
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 192:1, s. 148-157
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Tidskriftsartikel (refereegranskat)abstract
- Chondrocytes obtained from epiphyseal cartilage of fetal guinea pigs or ear cartilage of young rabbits were cultured in monolayer. The influence of colchicine, cytochalasin B, and p-nitrophenyl-β-d-xylopyranoside on secretion of proteoglycans was investigated. Radioactive sulfate was used as a precursor. As observed previously in other systems, β-d-xylosides initiated the synthesis of free chondroitin sulfate chains, competing with the endogenous proteoglycan core protein acceptor. The molecular weights of the chondroitin sulfate chains synthesized both on the xyloside and on the core-protein acceptor in maximally stimulated cells were similar and significantly lower than in proteoglycans synthesized in the absence of xyloside. The size of the chondroitin sulfate chains synthesized on the xyloside was inversely related to the concentration of this compound. This finding suggests that the chain length is dependent on the ratio between available acceptor and chain-lengthening enzymes or precursors. Cytochalasin B, a microfilament-modifying agent, inhibited proteoglycan synthesis, without any effect on secretion. Cells treated with cytochalasin B could be stimulated with β-d-xyloside to synthesize free chondroitin sulfate chains to the same relative degree as cells with intact microfilaments. Colchicine, an antimicrotubular agent, partially inhibited synthesis and secretion of proteoglycan. However, cells treated with colchicine could be stimulated with β-d-xyloside to synthesize and secrete free chondroitin sulfate chains to about the same relative degree as cells with intact microtubules. The data suggest that microtubules may have a facilitatory rather than an obligatory role in the secretion of proteoglycans and that at least part of the effect of colchicine is located at or after the site of glycosaminoglycan synthesis.
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- Lohmander, Stefan
(författare)
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Turnover of proteoglycans in guinea pig costal cartilage
- 1977
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 180:1, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- The turnover in vivo of proteoglycans of guinea pig costal cartilage was investigated using Na2 35SO4 as precursor. Proteoglycans were extracted with guanidine · HCl, at both low and high ionic strength, and purified and fractionated by ultracentrifugation in CsCl gradients under associative and dissociative conditions. The results suggest that the sulfate is incorporated into macromolecules of at least two major metabolic pools with half-lives of about 3 days and about 60-70 days, respectively. Molecules with a fast turnover were enriched in the low ionic strength extracts and in fractions containing small, nonaggregated proteoglycans. No substantial evidence was found for a precursor-product relationship between different fractions.
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- Madsen, Kjell, et al.
(författare)
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Production of cartilage-typic proteoglycans in cultures of chondrocytes from elastic cartilage
- 1979
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 196:1, s. 192-198
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Tidskriftsartikel (refereegranskat)abstract
- Chondrocytes from rabbit ear cartilage were isolated and cultured as monolayers in Ham's F-12 medium. The proteoglycans synthesized by short-term cultures formed a high proportion of aggregates and contained chrondroitin-4- and -6-sulfate in a 2:1 proportion. Dermatan sulfate was not present. The average molecular weight of the chondroitin sulfate was about 20,000. Keratan sulfate with an average molecular weight of about 6000 could be isolated from the proteoglycan monomers. Rabbit ear chondrocytes in culture thus produced proteoglycans comparable to those isolated from hyaline cartilage. Culture for longer periods and plating at lower density caused a decrease in the proportion of aggregated proteoglycans. Primary cultures continued to synthesize aggregated proteoglycans for at least 2 weeks, while subdivision of the cultures caused a shift toward the production of small-sized "ubiquitous proteoglycans." The synthesis of proteoglycan aggregates could, however, be partly restored by transfer of the monolayer cells to a suspension culture.
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- Madsen, Kjell, et al.
(författare)
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Proteoglycans synthesized by fetal Guinea pig chondrocytes in culture
- 1978
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Ingår i: Connective Tissue Research. - : Informa UK Limited. - 0300-8207 .- 1607-8438. ; 5:4, s. 205-210
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Tidskriftsartikel (refereegranskat)abstract
- Short term cultures were carried out with chondrocytes and tissue fragments from fetal guinea pig epiphyseal cartilage. Proteoglycans were isolated from these cultures and their properties were compared with those of pro-teoglycans from adult hyaline cartilage. It was concluded that the proteoglycans synthesized in culture were essentially similar to those present in cartilage matrix in vivo. The authors therefore suggest that fetal guinea pig chondrocytes cultured in monolayer or as aggregates in suspension constitute a useful system for the study of synthesis and secretion of proteoglycans.
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