Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study we describe a method to prepare membranes with high hyaluronan synthase activity from human glioma cells by pretreatment of the cells with both testicular hyaluronidase and 4-phorbol 12-myristate 13-acetate (PMA). A 23-fold increase in hyaluronan synthase activity was detected in comparison to untreated cells. Using isolated membranes as a source of hyaluronan synthase activity we demonstrate that chain elongation occurs at the reducing end of the hyaluronan molecule. We also present a method to solubilize hyaluronan synthase in active form with 1% digitonin. The solubilized synthase synthesized shorter hyaluronan chains than the membrane bound enzyme. Partial purification of the solubilized enzyme on a Superdex-200 column revealed a 12-fold increase in specific activity. Affinity purified polyclonal antibodies, raised against a synthetic peptide corresponding to the carboxy-terminus of the deduced protein sequence of human hyaluronan synthase recognized a 66 kDa component in the purified preparations. The elution position of the solubilized hyaluronan synthesizing activity immediately after V0 corresponding to a molecular mass of about 600 kDa, suggested that the 66 kDa enzyme forms a complex with other components which may have accessory or regulatory roles during hyaluronan synthesis.
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PMID:Characterization of hyaluronan synthase from a human glioma cell line. 955 98

In the present study we have investigated the expression of mRNAs for hyaluronan synthase isoforms (HAS1, HAS2 and HAS3) in different cells in response to various stimuli. Human mesothelial cells, which synthesize large amounts of hyaluronan, express mRNAs encoding all three HAS isoforms, whereas their transformed counterparts, mesothelioma cells, which produce only minute amounts of hyaluronan, express only HAS3 mRNA. Human lung fibroblasts and the glioma cell line U-118 MG express only the HAS2 and HAS3 genes. The expression of the transcripts was higher in subconfluent than in confluent cultures and was well correlated with the production of hyaluronan by the cells. Stimulation of mesothelial cells with platelet-derived growth factor-BB induced an up-regulation of mRNA for HAS2 to a maximum after 6 h of stimulation; HAS1 and HAS3 genes were only induced slightly. Transforming growth factor-beta1 reduced HAS2 mRNA slightly, and hydrocortisone reduced it strongly, within 6 h of stimulation in mesothelial cell cultures but did not significantly affect the expression of mRNAs for HAS1 and HAS3. Induction of HAS1 and HAS2 protein levels in response to the stimuli above correlated with HAS transcript levels. Thus the expression of the three HAS isoforms is more prominent in growing cells than in resting cells and is differentially regulated by various stimuli suggesting distinct functional roles of the three proteins.
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PMID:Expression of human hyaluronan synthases in response to external stimuli. 1079 10