Matrix-degrading protease ADAMTS-5 cleaves inter-α-inhibitor and releases active heavy chain 2 in synovial fluids from arthritic patients.

Destruction of the cartilage matrix in joints is an important feature of arthritis. Proteolytic degradation of cartilage glycoproteins can contribute to the loss of matrix integrity. Human inter-α-inhibitor (IαI), which stabilizes the extracellular matrix, is composed of the light-chain serine proteinase inhibitor bikunin and two homologous heavy chains (HC1 and HC2) covalently linked through chondroitin 4-sulfate. Inflammation promotes the transfer of HCs from chondroitin 4-sulfate to hyaluronan by tumor necrosis factor-stimulated gene-6 protein (TSG-6). This reaction generates a covalent complex between the heavy chains and hyaluronan that can promote leukocyte invasion. This study demonstrates that both IαI and the HC-hyaluronan complex are substrates for the extracellular matrix proteases ADAMTS-5 and matrix metalloprotease (MMP) -3, -7, and -13. The major cleavage sites for all four proteases are found in the C terminus of HC2. ADAMTS-5 and MMP-7 displayed the highest activity toward HC2. ADAMTS-5 degradation products were identified in mass spectrometric analysis of 29 of 33 arthropathic patients, indicating that ADAMTS-5 cleavage occurs in synovial fluid in arthritis. After cleavage, free HC2, together with TSG-6, is able to catalyze the transfer of heavy chains to hyaluronan. The release of extracellular matrix bound HC2 is likely to increase the mobility of the HC2/TSG-6 catalytic unit and consequently increase the rate of the HC transfer reaction. Ultimately, ADAMTS-5 cleavage of HC2 could alter the physiological and mechanical properties of the extracellular matrix and contribute to the progression of arthritis.

[Effect of Hanfangji compound on proliferation of hepatic stellate cells and expressions of TTR, ITIH1 and SERPINF2].

OBJECTIVE: To observe and compare the effects of Hanfangji Compound and IFN-gamma on expressions of transthyretin (TTR) , inter-alpha inhibitor H1 (ITIH1) and serpin peptidase inhibitor clade F member 2 (SERPINF2) of hepatic stellate cells (HSC-T6). METHOD: Hanfangji Compound and IFN-gammaof different concentrations were used in hepatic stellate cell-T6 (HSC-T6) for 48 h. Flow cytometer was used to detect the effects of Hanfangji Compound and IFN-gamma on HSC proliferation. RT-PCR method was adopted to detect mRNA expressions of TFR, ITIH1 and SERPINF2. TTR, ITIH1 and SERPINF2 secretions were detected by ELISA. The protein localizations of TTR, ITIH1 and SERPINF2 were examined by immune fluorescence. The protein expression of TfR and ITIHI were determined by Western blot. RESULT: After Hanfangji Compound and IFN-gamma were adopted in HSC-T6, compared with the control group, the cell proliferation was inhibited obviously (P < 0. 05) , protein expressions of TTR, ITIH1 and SERPINF2 and mRNA expression increased significantly, with certain correlation with concentrations of Hanfangji Compound. The 2. 5 g L-I Hanfangji Compound group was superior to the IFN-gamma group (P <0. 05). CONCLUSION: Hanfangji Compound can inhibit HSC proliferation, upregulated TTR, ITIH1 and SERPINF2 proteins and mRNA expression, which may be one of mechanisms of anti-hepatic fibrosis of Hanfangji Compound.

Identification of novel differentially expressed genes by the effect of a high-fat n-6 diet in experimental breast cancer.

In previous studies, we demonstrated that high corn oil diets promote the development of 7,12-dimethylbenz(alpha)anthracene (DMBA)-induced mammary tumors. In this study, we have investigated whether modulation of gene expression is one of the mechanisms by which this high-fat diet exerts such effects. Female Sprague-Dawley rats were induced with DMBA and fed normolipidic (3% corn oil) or high-fat (20% corn oil) diet. Screening of genes differentially expressed in adenocarcinomas from the high corn oil diet group compared to the control diet group was performed with cDNA microarrays. The resulting six upregulated and nine downregulated genes were validated by Northern blot and/or reverse transcription (RT)-polymerase chain reaction (PCR). Further investigation in a higher number of adenocarcinomas showed that in the high-fat n-6 diet group, where the tumor phenotype was verified to be more aggressive, the expression of submaxillary gland alpha-2u globulin, vitamin D(3)-upregulated protein 1 (VDUP1), H19, and the unknown function gene that codifies the expressed sequence tag (EST)-Rn.32385 was significantly decreased in comparison with the control group (C). These results, together with the fact that VDUP1, H19, and this globulin have been associated with cell proliferation and differentiation, open a new line of research about how the underexpression of these genes contributes to the stimulating effect of a high corn oil diet on experimental mammary carcinogenesis.

Development of a high-performance reporter plasmid for detection of chemicals with androgenic activity.

A number of chemicals are present in the environment, and some synthetic chemicals may disrupt endocrine function of wild animals and humans. An effective procedure to screen chemicals for endocrine modulating activity has been needed to ensure the safety of chemicals, and the reporter gene assay technique may provide a powerful tool for screening endocrine-disrupting chemicals. We have developed a high-performance reporter plasmid that can trigger high androgen-dependent induction with high selectivity by using mouse mammary tumor virus (MMTV) androgen-responsive elements and a partial fragment of the rat alpha(2u)-globulin promoter region. This new type plasmid can induce higher transcriptional activation than a commercial PGV-P-based construct bearing the SV40 promoter fragment, and the basal induction level of this plasmid is much lower than that of the PGV-P-based construct. Moreover, only androgen derivatives could selectively induce a high response in the reporter gene assay with the new reporter plasmid. This new type of reporter plasmid, ARE-AUG- Luc+, should be of value in endocrine research and in screening to identify endocrine-modulating chemicals.

Selenium regulates gene expression for estrogen sulfotransferase and alpha 2U-globulin in rat liver.

Dietary intake of the essential trace element selenium (Se) regulates expression of genes for selenoproteins and certain non-Se-containing proteins. However, these proteins do not account for all of Se's biological effects. The objective of this work was to identify additional genes whose expression is regulated by Se. Identification of these genes may reveal new functions for Se or define mechanisms for its biological effects. Weanling male Sprague-Dawley rats were fed a Torula yeast-based Se-deficient basal diet or the same diet supplemented with 0.5 mg Se/kg diet as sodium selenite for 13 weeks. Total RNA was used as template for RNA fingerprinting. Two differentially expressed cDNA fragments were identified and cloned. The first had 99% nucleotide identity with rat liver estrogen sulfotransferase (EST) isoform-6. The second had 99% nucleotide sequence identity with rat liver alpha 2u-globulin. The mRNA levels for both were markedly reduced in Se deficiency. Laser densitometry showed that EST mRNA in Se deficiency was 7.3% of that in Se-adequate rat liver. The level of alpha 2u-globulin mRNA in Se-deficient rat liver was only 12.6% of that in Se-adequate rat liver. These results indicate that dietary Se may play a role in steroid hormone metabolism in rat liver.

Molecular cloning and sequencing of cDNAs encoding three heavy-chain precursors of the inter-alpha-trypsin inhibitor in Syrian hamster: implications for the evolution of the inter-alpha-trypsin inhibitor heavy chain family.

Complementary DNAs encoding precursors of the three heavy chains (HC1, HC2, HC3) of the inter-alpha-trypsin inhibitor in Syrian hamster liver were sequenced. The deduced amino acid sequence of the HC1 precursor was 87, 82, and 79% identical with those of the HC1 precursors from mouse, man and pig, respectively. The HC2 and HC3 precursors showed similar degrees of sequence identity with the corresponding human and mouse HC precursors. When the hamster HC1 precursor was compared with its own HC2 and HC3 precursors, however, even the most highly conserved segment consisting of 565 amino acid residues, i.e., about 2/3 of the whole molecule, showed only about 35 and 65% sequence identity, respectively. Essentially the same results were obtained on the intra-species comparisons of three subfamilies in man and mouse. Thus, the interspecies conservation of a given HC subfamily is much greater than the similarity between the three different HC subfamilies within a given species. These results suggest that (i) higher vertebrates possess three HC genes which have been evolving independently of each other under purifying selection; (ii) the diversification of the three HC subfamilies, for which the middle regions of the molecules were mainly responsible, occurred before eutherian radiation; and (iii) each HC subfamily may have unique function(s), although at present virtually nothing is known about the functional differences between the three HC subfamilies.

The three heavy-chain precursors for the inter-alpha-inhibitor family in mouse: new members of the multicopper oxidase protein group with differential transcription in liver and brain.

The inter-alpha-inhibitor (I alpha I) family is comprised of the plasma protease inhibitors I alpha I, inter-alpha-like inhibitor (I alpha LI), pre-alpha-inhibitor (P alpha I) and bikunin. I alpha I, I alpha LI and P alpha I are distinct assemblies of bikunin with one of three heavy (H) chains designated H1, H2 and H3. These H chains and bikunin are respectively encoded by a set of three H genes and an alpha 1-microglobulin/bikunin precursor (AMBP) gene. All four gene products undergo maturation steps from precursor polypeptides. The full-length cDNAs for the H1-, H2- and H3-chain precursors were cloned from a mouse liver cDNA library and sequenced. Extensive searches of amino acid sequence similarities to other proteins in databanks revealed (i) a highly significant similarity of the C-terminal sequence in the three H-chain precursors to the multicopper-binding domain in the group of multicopper oxidase proteins and (ii) the presence of von Willebrand type-A domains in the mature H chains. Amino acid sequence comparisons between the three mouse H1-, H2- and H3-chain precursors and their human counterparts allowed us to appraise the timing and order of occurrence of the three H-chain genes from a shared ancestor during mammalian evolution. Owing to a multiple alignment of the six mouse and human nucleotide sequences for these H-chain precursors, a reverse transcriptase PCR assay with degenerate oligonucleotides was designed, allowing us to (i) present evidence that no mRNAs for further H genes exist in mouse liver and (ii) demonstrate a previously undescribed transcription of the H2- and H3-chain mRNAs in mouse brain, which contrasts with the expression of all four, H1, H2, H3 and AMBP, mRNAs in liver.

Accumulation of alpha 2u-globulin in the renal proximal tubules of male rats exposed to unleaded gasoline.

Saturated branched-chain aliphatic hydrocarbons, found in motor fuels, induce nephrotoxicity in male rats. Treatment of male rats with unleaded gasoline (0.04-2.0 ml/kg body wt, po) for 9 days increased markedly the number and size of hyaline (protein resorption) droplets in epithelial cells of the renal proximal convoluted tubules (PCT) and enhanced cellular exfoliation at high dose levels. No other treatment-related pathological effects were observed in the glomeruli, distal tubules, or medulla. The renal content of alpha 2u-globulin, a major urinary protein of male rats, was increased maximally by about 4.4-fold after gasoline administration (1.0 ml/kg, po, 9 days); no further increase was observed at higher doses. Immunoperoxidase staining of kidney tissue sections for alpha 2u-globulin revealed large accumulations of antigen localized in many of the PCT epithelial cells which contained hyaline droplets. The hepatic content of alpha 2u-globulin and its mRNA were not altered by gasoline administration. These data show, for the first time, that alpha 2u-globulin is accumulated in the kidneys of gasoline-intoxicated male rats and sequestered specifically in some of the hyaline droplets characteristic of gasoline-induced nephropathy. A hydrocarbon-induced defect in the renal lysosomal degradation of low-molecular-weight urinary proteins, rather than increased synthesis of these proteins, appears to cause hyaline droplet accumulation.