Keratan sulfate

About: Keratan sulfate is a research topic. Over the lifetime, 1253 publications have been published within this topic receiving 57984 citations. The topic is also known as: keratan sulfate & KS.

The proteoglycans and glycosaminoglycan chains of rabbit synovium.

Abstract: The synovial lining of joint capsules is important because it controls the flow of fluid into and out of the joint cavity. Physiological studies have shown that the glycosaminoglycans, particularly hyaluronan, have an important role in the control of fluid flow. The distribution of the glycosaminoglycans and proteoglycans in the synovium and subsynovium of rabbits (approximately 12 weeks old) was, therefore, determined immunohistochemically. Hyaluronan, chondroitin-4- and chondroitin-6-sulphates and keratan sulphate are present in the synovium and subsynovium; chondroitin-4-sulphate is at higher concentrations than chondroitin-6-sulphate. The core proteins of the chondroitin sulphate proteoglycans, biglycan and decorin, and of the keratan sulphate proteoglycan, fibromodulin, are also present. To date, fibromodulin has not been located in other synovial linings, and its presence corroborates that of keratan sulphate.

Structure and Sequence of the Gene Encoding Human Keratocan

Abstract: Keratocan is one of the three major keratan sulfate proteoglycans characteristically expressed in cornea. We have isolated cDNA and genomic clones and determined the sequence of the entire human keratocan (Kera) gene. The gene is spread over 7.65 kb of DNA and contains three exons. An open reading frame starting at the beginning of the second exon encodes a protein of 352 aa. The amino acid sequence of keratocan shows high identity among mammalian species. This evolutionary conservation between the keratocan proteins as well as the restricted expression of Kera gene in cornea suggests that this molecule might be important in developing and maintaining corneal transparency.

The in vitro cell culture age and cell density of articular chondrocytes alter sulfated-proteoglycan biosynthesis.

Abstract: The effect of cell culture age and concomitant changes in cell density on the biosynthesis of sulfated-proteoglycan by rabbit articular chondrocytes in secondary monolayer culture was studied. Low density (LD, 2 d), middle density (MD, 5-7 d), and high density (HD, 12-15 d) cultures demonstrated changes in cellular morphology and rates of DNA synthesis. DNA synthesis was highest at LD to MD densities, but HD cultures continued to incorporate [3H]-thymidine. LD cultures incorporated 35SO4 into sulfated-proteoglycans at a higher rate than MD or LD cultures. The qualitative nature of the sulfated-proteoglycans synthesized at the different culture ages were analyzed by assessing the distribution of incorporated 35SO4 in associative and dissociative CsCI density gradients and by elution profiles on Sepharose CL-2B. Chondrocytes deposited into the extracellular matrix (cell-associated fraction) 35SO4-labeled proteoglycan aggregate. More aggregated proteoglycan was found in the MD and HD cultures than at LD. A 35SO4-labeled aggregated proteoglycan of smaller hydrodynamic size than that found in the cell-associated fraction was secreted into the culture medium at each culture age. The proteoglycan monomer (A1D1) of young and older cultures had similar hydrodynamic sizes at all cell culture ages and cell densities. The glycosaminoglycan chains of A1D1 were hydrodynamically larger in the younger LD cultures than in the older HD cultures and consisted of only chondroitin 6 and 4 sulfate chains. A small amount of chondroitin 4,6 sulfate was detected, but no keratan sulfate was measured. The A1D2 fractions of young LD cultures contained measurable amounts of dermatan sulfate; no dermatan sulfate was found in older MD or HD cultures. These studies indicated that chondrocytes at LD synthesized a proteoglycan monomer with many of the characteristics of young immature articular cartilage of rabbits. These results also indicated that rapidly dividing chondrocytes were capable of synthesizing proteoglycans which form aggregates with hyaluronic acid. Culture age and cell density appears primarily to modulate the synthesis of glycosaminoglycan types and chain length. Whether or not these glycosaminoglycans are found on the same or different core proteins remains to be determined.

Reversible Effects of Retinoic Acid on Glycosaminoglycan Synthesis during Differentiation of HL-60 Leukemia Cells

Abstract: Glycosaminoglycans (GAGs) play an important role in cell-cell and cell-substratum interactions, and undergo specific changes during neutrophil development. Previous studies (Luikart, S. D., Maniglia, C. A., and Sartorelli, A. C. Cancer Res., 44: 2907–2912, 1984) have shown that both dimethyl sulfoxide and 4-β-phorbol-12-β-myristate-13-α-acetate decreased GAG production by a hypoxanthine-guanine phosphoribosyl transferase-deficient clone of HL-60 promyelocytic leukemia cells prior to the appearance of a mature myeloid or monocytoid phenotype. To expand these investigations further, GAGs were analyzed by cetylpyridinium chloride precipitation and DEAE-Sephacel ion-exchange chromatography after labeling of parental HL-60 cultures with [ 35 S]sulfate and d-[ 3 H]glucosamine for 6 h, following treatment with 1 µm all- trans retinoic acid (RA). Chondroltin sulfate represented the major GAG species produced, although endo-β-galactosidase-sensitive undersulfated macromolecules which possibly might be keratan sulfate, were also identified. GAG production decreased over a time period of 144 h in culture. RA treatment reduced the amount of radiolabeled cell-associated GAGs by 50% after 48, 96, and 144 h of exposure. In contrast, commitment to myelocytic maturation of the majority ( i.e. , approximately 60%) of the cells occurred between 72 and 96 h of RA treatment. Concurrently with the appearance of mature granulocytic cells, two-thirds of the radiolabeled GAGs were recovered from the medium, compared to one-third in untreated cultures, a phenomenon that resulted in an overall alteration in the distribution of GAGs. When RA was removed by washing after either 48 h ( i.e. , precommitment to differentiation) or 96 h ( i.e. , postcommitment to differentiation), a 1.5- to 3.5-fold increase in GAG production was noted 48 h later; this increase was unrelated to the medium change or to alterations in cell cycle distribution. The amounts of endo-β-galactosidase-sensitive macromolecules were unaltered. Thus, although 1 µm RA inhibited the synthesis of chondroitin sulfate by HL-60 leukemia cells, this inhibition was reversible by removal of the drug and appeared to be unrelated to the commitment to myelocytic maturation.