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Stimulation of heparan sulphate synthesis in cultured rat hepatocytes by (+)-catechin.

ABSTRACT: The secretion of heparan sulphate by cultured rat hepatocytes was increased in the presence of (+)-catechin. The increase was due to a new species of heparan sulphate that lacked the carbohydrate-protein linkage between xylose and serine in normal heparan sulphate proteoglycan. The mean molecular weight of this heparan sulphate varied between 6300 and 9500, was not affected by treatment with alkali or Pronase and was 2-3-fold lower than that of chains released from heparan sulphate proteoglycan. After digestion with Pronase, only a minor fraction of chains contained serine, and after treatment with alkali and NaB3H4 reduction less than 5% of the chains exposed [3H]xylitol at the reducing terminals. These results suggested that (+)-catechin or metabolites of it acted as acceptors of heparan sulphate synthesis. In cultures treated wih cycloheximide, synthesis of heparan sulphate decreased to less than 5%. (+)-Catechin could restore the heparan sulphate synthesis to almost normal values. The (+)-catechin-induced heparan sulphate was secreted. Only a small fraction was incorporated into the plasma membrane or other cellular compartments. This may indicate that the protein core is essential for association of heparan sulphate with cellular compartments.

SUBMITTER: Sinn W

PROVIDER: S-EPMC1163501 | biostudies-other | 1981 Oct

REPOSITORIES: biostudies-other

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Project description:DNA microarray is a powerful tool in biomedical research. However, transcriptomic profiling using DNA microarray is subject to many variations including biological variability. To evaluate the different sources of variation in mRNA gene expression profiles, gene expression profiles were monitored using the Affymetrix RatTox U34 arrays in cultured primary hepatocytes derived from six rats over a 26 hour period at 6 time points (0 h, 2h, 5h, 8h, 14 h and 26 h) with two replicate arrays at each time point for each animal. In addition, the impact of sample size on the variability of differentially expressed gene lists and the consistency of biological responses were also investigated. Excellent intra-animal reproducibility was obtained at all time points with 0 out of 370 present probe sets across all time points showing significant difference between the 2 replicate arrays (3-way ANOVA, p <or= 0.0001). However, large inter-animal biological variation in mRNA expression profiles was observed with 337 out of 370 present probe sets showing significant differences among 6 animals (3-way ANOVA, p <or= 0.05). Principal Component Analysis (PCA) revealed that time effect (PC1) in this data set accounted for 47.4% of total variance indicating the dynamics of transcriptomics. The second and third largest effects came from animal difference, which accounted for 16.9% (PC2 and PC3) of the total variance. The reproducibility of gene lists and their functional classification was declined considerably when the sample size was decreased. Overall, our results strongly support that there is significant inter-animal variability in the time-course gene expression profiles, which is a confounding factor that must be carefully evaluated to correctly interpret microarray gene expression studies. The consistency of the gene lists and their biological functional classification are also sensitive to sample size with the reproducibility decreasing considerably under small sample size.

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Stimulation of heparan sulphate synthesis in cultured rat hepatocytes by (+)-catechin.

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