Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.36 (hyaluronidase)
 4,606 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deposition of glycosaminoglycan is one of the histological features of Graves' ophthalmopathy. Although retroocular tissue fibroblasts are considered to be responsible for glycosaminoglycan accumulation, it is not known what is stimulating the fibroblasts. There are studies which are in support of and against the role of anti-TSH receptor antibodies in the pathogenesis of Graves' ophthalmopathy. TSH-receptor antibodies increase cAMP as a second messenger in thyroid cells. We studied the effects of dibutyryl cyclic AMP (Bt2 cAMP) on glycosaminoglycan synthesis by retroocular tissue fibroblasts in order to known whether cAMP can modulate glycosaminoglycan synthesis. Retroocular tissue fibroblasts mainly synthesize hyaluronan, the large chondroitin sulfate proteoglycan and the small chondroitin sulfate proteoglycan as glycosaminoglycan in cell culture. The amount of hyaluronan synthesis was measured as [3H]glucosamine incorporation into macromolecule susceptible to hyaluronidase digestion (from Streptomyces hyaluronlyticus). The amount of proteoglycan synthesis was measured as [35S]sulfate incorporation into macromolecules in medium and cell layer fraction. Proteoglycans in medium were further separated into the large proteoglycan and the small proteoglycan on a Superose 6 column. Bt2 cAMP increased both hyaluronan and proteoglycan synthesis by retroocular tissue fibroblasts, especially stimulating the secretion of the large proteoglycan synthesis by retroocular tissue fibroblasts, especially stimulating the secretion of the large proteoglycan. Effects of Bt2 cAMP on glycosaminoglycan synthesis were then compared with those in adult skin fibroblasts. Although the magnitude of response between the two was indistinct, the stimulation of the large proteoglycan synthesis by Bt2 cAMP was more prominent in retroocular tissue fibroblasts. The results suggest that the regulation of glycosaminoglycan synthesis by retroocular tissue fibroblasts is different from that by adult skin fibroblasts. Although further studies are required to determine its actual role, cAMP stimulates glycosaminoglycan synthesis by retroocular tissue fibroblasts and underlies the mechanism in Graves' ophthalmopathy.
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PMID:Effects of dibutyryl cyclic AMP on hyaluronan and proteoglycan synthesis by retroocular tissue fibroblasts in culture. 770 88

Leukoregulin, a 50-kDa glycoprotein lymphokine, can regulate the extracellular matrix in dermal fibroblasts. Here we investigate the effects of leukoregulin on the synthesis of glycosaminoglycans in human orbital fibroblasts. We demonstrate that leukoregulin enhances the incorporation of [3H]glucosamine into glycosaminoglycans. The effect is dose dependent in the concentration range tested (0.1-2 U/ml), is maximal at 1 U/ml, and is time dependent. [3H]glycosaminoglycan accumulation is enhanced 7.67 +/- 1.23-fold (SE, n = 7) in orbital fibroblast strains. Pulse-chase studies indicate that this enhanced accumulation is not a result of a decreased rate of macromolecular degradation. Radiolabeled material induced by leukoregulin is sensitive to Streptomyces hyaluronidase digestion. Dexamethasone (10(-8) M) and cycloheximide (10 micrograms/ml) can block the cytokine's stimulation of hyaluronan synthesis. [35S]sulfate incorporation into glycosaminoglycan is unaffected by leukoregulin. In dermal fibroblasts, leukoregulin increased hyaluronan synthesis 3.66 +/- 0.37-fold (n = 5 strains, P < 0.02 compared with orbit). The increase in hyaluronan synthesis in orbital fibroblasts is substantially greater than that observed previously with other cytokines, making leukoregulin a candidate molecular trigger in Graves' ophthalmopathy.
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PMID:Leukoregulin is a potent inducer of hyaluronan synthesis in cultured human orbital fibroblasts. 786 77

Thyroid eye disease (TED) is a debilitating disorder characterized by the accumulation of adipocytes and hyaluronan (HA). Production of HA by fibroblasts leads to remarkable increases in tissue volume and to the anterior displacement of the eyes. Prostaglandin D(2) (PGD(2)), mainly produced by mast cells, promotes orbital fibroblast adipogenesis. The mechanism by which PGD(2) influences orbital fibroblasts and their synthesis of HA is poorly understood. We report here that mast cell-derived PGD(2) is a key factor that promotes HA biosynthesis by orbital fibroblasts. Primary orbital fibroblasts from TED patients were isolated and used to test the effects of PGD(2), prostaglandin J(2), as well as prostaglandin D receptor (DP) agonists and antagonists on HA synthesis. The expression of HA synthase (HAS), hyaluronidase, DP1, and DP2 mRNA levels was assessed by PCR. Small interfering RNAs against HAS1 or HAS2 were used to assess the importance of HAS isoforms on HA production. Treatment of human orbital fibroblasts with PGD(2) and PGJ(2) increased HA synthesis and HAS mRNA. HAS2 was the dominant isoform responsible for HA production by PGD(2). The effect of PGD(2) on HA production was mimicked by the selective DP1 agonist BW245C. The DP1 antagonist MK-0524 completely blocked PGD(2)-induced HA synthesis. Human mast cells (HMC-1) produced PGD(2). Co-culture of HMC-1 cells with orbital fibroblasts induced HA production and inhibition of mast cell-derived PGD(2) prevented HA synthesis. Mast cell-derived PGD(2) increased HA production via activation of DP1. Selectively targeting the production of PGD(2) and/or activation of DP1 may prevent pathological changes associated with TED.
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PMID:Mast cell-derived prostaglandin D2 controls hyaluronan synthesis in human orbital fibroblasts via DP1 activation: implications for thyroid eye disease. 2030 56