Close kinship of human 20alpha-hydroxysteroid dehydrogenase gene with three aldo-keto reductase genes

BACKGROUND

20alpha-Hydroxysteroid dehydrogenase (HSD) is a member of the aldo-keto reductase (AKR) superfamily and catalyses the reaction of progesterone to the inactive form 20alpha-hydroxyprogesterone. Progesterone plays an important role in the maintenance of pregnancy, and, in rodents, plasma progesterone levels decrease abruptly just before parturition. The induction of 20alpha-HSD is thought to be responsible for the decrease in plasma progesterone at term. High homology between human 20alpha-HSD [AKR 1C1] cDNA with other AKRs had caused difficulty in gene isolation and expression analysis. Thus, the metabolism of progesterone in the human reproductive system remained unclear.

RESULTS

By hybridization with rat 20alpha-HSD [AKR 1C8] cDNA and high-stringency polymerase chain reaction (PCR) with gene-specific primers, we were able to isolate the human 20alpha-HSD, bile acid-binding protein (BABP) [AKR 1C2], prostaglandin F synthase (PGFS) [AKR 1C3], and dihydrodiol dehydrogenase (DD) 4 [AKR 1C4] genes. These genes had similar exon-intron organizations and shared a high homology. The four recombinant enzymes encoded by these genes showed distinct substrate specificity. By reverse transcription-PCR analysis, human 20alpha-HSD, BABP and PGFS mRNAs were expressed ubiquitously, while DD4 mRNA was restricted to the liver. Promoter activities of the 20alpha-HSD, BABP and PGFS genes were high, both in ovarian granulosa cells and hepatocytes. Radiation hybridization analysis revealed that all these genes were located close together in chromosome 10.

CONCLUSION

The human gene encoding for the progesterone-metabolizing enzyme 20alpha-HSD in the female reproductive system was cloned, and its expression and gene localization were elucidated. BABP, PGFS and DD4 genes, which were highly homologous to the 20alpha-HSD gene, were also cloned, and their structure and function were characterized.

A product of growth arrest-specific gene 6 modulates scavenger receptor expression in human vascular smooth muscle cells

Although Gas6 is identified as a growth factor for vascular smooth muscle cells (VSMCs), its roles in these cells have not been clearly elucidated. To examine the role of Gas6 in atherosclerosis, we examined the effects of Gas6 on scavenger receptor family expression in VSMCs. Scavenger receptor class A, one of the scavenger receptor family members, was upregulated in VSMCs by Gas6. Furthermore, the atherogenic lipoprotein, oxidized LDL, induced Gas6 production in these cells. These results indicate that Gas6 plays an important role in foam cell formation in human VSMCs.

Adult T-cell leukemia/lymphoma in which the pathohistological diagnosis was identical to that of Ki-1 positive anaplastic large cell lymphoma

A 65-year-old man developed severe lumbago and a loss of appetite two months before presentation. A computerized tomograph at admission revealed soft tissue masses destroying the Th12, L4 and L5 vertebral bones. We diagnosed the lesions to be metastatic bone tumors, but the primary focus could not be determined. Just after the irradiation treatment, abnormal lymphocytes were detected in the peripheral blood cells. Under the suspicion of adult T-cell leukemia/ lymphoma (ATL), we thus performed a lymph node biopsy. The specimens were histologically composed of Ki-1 positive anaplastic large cell lymphoma (ALCL). The lymphoma cells demonstrated a biclonal integration of HTLV-1 proviral DNA. After 6 cycles of chemotherapy, the patient has demonstrated a partial and favorable remission from ATL.

Transactivation of the human cdc2 promoter by adenovirus E1A. E1A induces the expression and assembly of a heteromeric complex consisting of the CCAAT box binding factor, CBF/NF-Y, and a 110-kDa DNA-binding protein

Cyclin-dependent kinases (CDKs) play an important role in the eukaryotic cell cycle progression. Cdc2 (CDK1) is expressed in late G(1)/S phase and required for G(2) to M phase transition in higher eukaryotes. The oncoproteins, SV40 large T antigen and adenovirus E1A, induce a 110-kDa protein which specifically recognizes the two inverted CCAAT motifs of the cdc2 promoter in cycling cells and plays an essential role in transactivation of the human cdc2 promoter. Since these CCAAT motifs also conform to the consensus binding sites for the ubiquitous heterotrimeric transcription factor, CBF/NF-Y, the role of CBF/NF-Y in the transactivation of the cdc2 promoter was examined in this study. Our results indicate that CBF/NF-Y and the 110-kDa protein interact with the CCAAT box motif to form a heteromeric complex. However, mutagenesis of the pentanucleotide CCAAT motif or in the presence of urea greater than 2.5 M, no heteromeric complex was formed. In contrast, the 110-kDa protein could still bind the mutant CCAAT motif or with the wild type motif in the presence of 2.5 M urea. Furthermore, E1A.12S induced the gene expression of all three subunits of CBF/NF-Y. Coexpression of E1A and a dominant negative mutant NF-YA subunit significantly reduced the E1A-mediated transactivation of the cdc2 promoter in a dose-dependent manner. These results support the conclusion that E1A protein mediates optimal transactivation of the human cdc2 promoter by inducing the expression and assembly of a heteromeric complex consisting of the 110-kDa protein and the CBF/NF-Y which interacts with the two CCAAT motifs of the cdc2 promoter.

Shortened microsatellite d(CA)21 sequence down-regulates promoter activity of matrix metalloproteinase 9 gene

One characteristic elements in the promoter of the matrix metalloproteinase 9 (MMP-9) gene is the d(CA) repeat. To investigate whether this element regulates the transcription of the MMP-9 gene and its enzymatic activities, we sequenced the promoter region isolated from esophageal carcinoma cell lines. TE9 cells with low MMP-9 enzymatic activity had the number of d(CA) repeats shortened from 21 to 14 or 18. TE8, TE10 and TE11 cells with high MMP-9 activities had 21 or 23 d(CA) repeats. Luciferase assays using MMP-9 promoter containing 18, 14 or 0 d(CA) repeats showed transcriptional activities which were 50, 50 or 5%, respectively, of the level achieved with promoter containing 21 d(CA) repeats. Sequence analysis of the promoter of 223 Japanese subjects revealed that most had two alleles with 20, 21 or 22 d(CA) repeats, whereas six had one or two alleles with 14, 18 or 19 d(CA) repeats. We postulate that length alteration of the d(CA) repeat causes phenotypic differences among carcinoma cells and that microsatellite instability may contribute to the polymorphism of d(CA) repeat length.

Myoepithelioma of soft tissue

A myoepithelioma occurred in the subcutaneous tissue of the right shoulder of a 28-year-old man. The well-demarcated nodular tumor (3. 0 x 2.8 cm) was located in the subcutaneous tissue with no adhesion to the deltoid muscle. The tumor was composed of a fascicular proliferation of spindle cells with variable amounts of stroma and showed areas of sheets of epithelioid cells. In most areas, the tumor cells had uniform nuclei, but pleomorphic epithelioid cells were focally present. Mitotic activity was three per 10 high-power fields. No ductular structure was found throughout the tumor. Immunohistochemical and ultrastructural studies confirmed the myoepithelial origin of the tumor cells. The occurrence of myoepithelioma in the subcutaneous tissue has been rarely reported. Even though the tumor showed no aggressive behavior on the 2-year follow-up, it is still too early to comment definitely on the behav- ior of myoepithelioma of the subcutaneous tissue. This case provides further information about soft tissue myoepithelioma.

Ileal varices associated with recurrent bleeding in a patient with liver cirrhosis

We report a rare case of massive and recurrent bleeding from ileal varices in a patient with hepatitis C virus-positive liver cirrhosis. A 66-year old woman, who had undergone laparotomy and blood transfusion 36 years before (because of an extrauterine pregnancy) and endoscopic sclerotherapy for esophageal varices 1 year previously, was admitted to our hospital with loss of bright red blood per rectum. The bleeding was massive and recurrent, and frequent blood transfusions were required. Endoscopic studies failed to find the bleeding site. In the venous phase of selective superior mesenteric angiography, mesenteric varices in the lower part of the abdominal cavity were observed. Laparotomy was performed to control the repeated bleeding which had lasted for more than 1 month. Varices communicating with the right ovarian vein were found on the ileal wall and segmental resection of the ileum was performed. Histological examination demonstrated a massive varicose vein and several dilated veins in the submucosa. The patient's postoperative course was favorable, with no hemorrhagic events during a follow-up of more than 6 months after surgery. Ileal varices should be considered in the diagnosis of a patient who presents with lower gastrointestinal bleeding and portal hypertension.

Distribution of cadmium and metallothionein in CdCl2-exposed rat kidney: relationship with apoptosis and regeneration

Male Sprague-Dawley rats were injected subcutaneously with 0.6 mg cadmium/kg bodyweight per day for 6 weeks. In each week of exposure, rats were killed and the localization of cadmium and metallothionein in the kidney was studied by histochemical and immunohistochemical methods. Although cadmium was localized throughout the proximal tubules during exposure, apoptosis and subsequent regeneration were observed mainly in the straight portion of the proximal tubules after 4 weeks of exposure. The distribution of tubular injury may thus not necessarily coincide with that of cadmium. Expression of metallothionein was also detected in the cytoplasm and nuclei of the convoluted and the straight portion of the proximal tubules, but the latter became positive in accordance with apoptosis and regeneration. These results suggest a close relationship between metallothionein distribution and tubular cell regeneration.

Transactivation of the human cdc2 promoter by adenovirus E1A in cycling cells is mediated by induction of a 110-kDa CCAAT-box-binding factor

Cyclin-dependent protein kinases (Cdks) are key regulatory proteins of the eukaryotic cell cycle. Cdc2 is expressed in late G1/S phase and functions in the G2 to M phase transition. Adenovirus E1A proteins are known to induce the expression of p34cdc2 and DNA synthesis in normal quiescent cells. In this study, mutational analysis of the human cdc2 promoter revealed that transactivation of the promoter by the E1A proteins in cycling cells is mediated through the two CCAAT box binding motifs. A 110-kDa protein (CBF/cdc2) was identified in nuclear extracts from monkey kidney (CV-1) cells stably expressing E1A as well as from adenovirus-transformed human 293 cells. Further, we show that this EIA-inducible CBF/cdc2 is related to the CBF which was shown to activate the heat shock protein 70 promoter. Analyses of the functional domain(s) of E1A required for the induction of the CBF and transactivation of the cdc2 promoter in these conditions revealed that E1A mutants which were defective in binding the pRB family of proteins or the cellular p300 protein were still active in assays measuring the induction of the CBF and transactivation of the cdc2 promoter, albeit with reduced efficiencies. But the E1A mutant which lost both functional domains was inactive in these assays. These results suggest that E1A has redundant functional domains for the induction of the 110-kDa CBF and activation of human cdc2 gene expression.

Deregulation of cdc2 gene expression correlates with overexpression of a 110 kDa CCAAT box binding factor in transformed cells

Eukaryotic cell cycle progression is regulated by an orderly and sequential activation of several cyclin-dependent kinases, which phosphorylate key substrates during this process. p34cdc2, the catalytic subunit of cdc2 kinase, is expressed at the late G1/S boundary and is required for the G2-->M phase transition. Transactivation of the human cdc2 promoter by the DNA tumor virus-encoded oncogenic protein SV40 large T antigen is mediated by induction of a novel 110 kDa CCAAT box binding factor (CBF/cdc2). To investigate whether induction of CBF/cdc2 is an intrinsic property of the viral oncoprotein or is a common event during transformation of normal cells, expression of CBF/cdc2 was analyzed in many human tumor cell lines and in rodent cells spontaneously transformed or stably expressing various oncogenes. Our results showed that CBF/cdc2 was overexpressed in all transformed cells examined, including human 293, MCF-7, HeLa and HepG2 cells. Moreover, expression of CBF/cdc2 was elevated in spontaneously transformed rat liver epithelial cells (C4T), but not detectable in the non-tumorigenic parental (RLE) cells. The elevated levels of CBF/cdc2 expression in C4T cells correlated well with increased cdc2 mRNA and p34cdc2 levels. CBF/cdc2 was also overexpressed in a rat liver epithelial cell line (WB) stably transfected with various oncogenes, v-myc, v-Ha-ras and mutated rat neu and v-src. Using an electrophoretic mobility shift assay, specific binding of CBF/cdc2 to the CCAAT box motifs of the human cdc2, cycA and cdc25C promoters was detected, suggesting that transcription of these cell cycle regulatory genes are coordinately activated by CBF/cdc2.

Altered membrane skeleton of red blood cells participates in cadmium-induced anemia

Poikilocytosis of red blood cells (RBCs) was observed to be associated with anemia in rats given subcutaneous injections of cadmium (Cd). Phase-contrast light and scanning electron microscopic examinations revealed that acanthocytes appeared in the early stages of administration, and that the number of RBC fragments increased later. Ultrastructural analysis of RBC ghosts by negative staining demonstrated that the normal lattice structure of the membrane skeleton was abolished. The osmotic fragility curve of the Cd-exposed RBCs disclosed that most of the cells were less fragile than control RBCs. These data indicate that the RBC membrane skeleton is initially altered by Cd-exposure, followed by deformation of the cell, thus promoting intrasplenic hemolysis, and resulting in anemia.

Glycated protein-iron chelate increases lipid peroxide level in cultured aortic endothelial and smooth muscle cells

Formation of an iron chelate of glycated protein was demonstrated by the appearance of an absorption peak at approximately 270 nm after mixing glycated bovine serum albumin with FeCl3. This peak disappeared and a new peak appeared at approximately 420 nm to form an isosbestic point at approximately 340 nm by the addition of deferoxamine mesylate, an iron-chelating agent, to the mixture, thus confirming the formation of the iron chelate of the glycated protein in the mixture. The lipid peroxide level was increased markedly in endothelial cells and slightly in smooth muscle cells from bovine aorta incubated in the medium containing glycated fetal bovine serum-iron chelate. Morphological observation by phase-contrast microscopy and scanning electron microscopy revealed that the glycated fetal bovine serum-iron chelate caused intense damage to the endothelial cells. These results indicate that glycated protein-iron chelate provokes lipid peroxidation, which explains at least in part the mechanism of atherogenesis found in diabetic patients.

A role for interleukin 4 in production of matrix metalloproteinase 1 by human aortic smooth muscle cells

Effect of interleukin 4 (IL-4) on the production of matrix metalloproteinase 1 (MMP-1) by normal and immortalized human intimal smooth muscle cells (SMC) was investigated. The production of the precursors of MMP-1 by intimal SMC was enhanced in a dose-dependent manner by addition of IL-4 to the culture medium, whereas the cytokine also showed an inhibitory effect on DNA synthesis in the cells. In addition, mRNA of IL-4 was found in the atherosclerotic and nonatherosclerotic areas of the intima. Although the production of MMP-1 and the proliferation of SMC are thought to play an important role in reconstruction of the intima during atherogenesis, our results suggest a possible role of IL-4 induced MMP-1 in inhibiting tissue remodeling caused by a variety of arterial disorders including atherosclerosis.

Effects of short- and long-term exposure to linoleic acid hydroperoxide on cytosolic calcium ion level of human aortic intimal smooth muscle cells in vitro

When cultured intimal smooth muscle cells from human aorta were exposed for a short period of time (25 sec) to linoleic acid hydroperoxide (100 nmol/ml), influx of calcium ions into the cytosol of these cells was provoked, and a temporal increase in cytosolic calcium ion level was observed. Two calcium channel blockers inhibited this influx. Long-term exposure (4 min) of these cells to the hydroperoxide also provoked the influx of calcium ions, which resulted in a longer time of the calcium ion increase. In the latter case, however, the calcium channel blocker inhibited the initial influx, but then the influx started and continued even in the presence of the blocker. Such difference in exposure time-dependent effects should be taken into account in considering pathological roles of lipid hydroperoxides.

Response to platelet-derived growth factor by phenotypically different cultured human aortic smooth muscle cells

We investigated the effects of PDGF on DNA synthesis and mitogen-activated protein (MAP) kinase activity, and demonstrated that the adult intimal SMC was concentration-dependently stimulated by all PDGF isoforms in terms of both [3H]thymidine incorporation and MAP kinase activation, with PDGF-BB and -AB being more potent than PDGF-AA. The intimal SMCs and the neonatal SMCs showed a similar response with regard to MAP kinase activation. On the other hand, the intimal SMCs expressed many more PDGF receptors than the adult medial SMCs, which expressed a greater amount of PDGF-A chain mRNA and showed a lesser response to PDGFs. These results suggest that the intimal SMCs have a relatively high potential to react to exogenous PDGFs, whereas the adult medial SMCs depend on endogenous or autocrine secretion of PDGF-AA.

Pathological study of splenomegaly associated with cadmium-induced anemia in rats

Splenomegaly was observed both in male and female Sprague-Dawley rats after 1 week of exposure to CdCl2 (0.6 mg Cd/kg/day). Spleen weight reached about double that in controls by 8 weeks of Cd exposure. Histopathological examination of the enlarged spleen revealed that iron- and lipid-laden histiocytes were clustered in the periarterial lymphatic sheath, and the red pulp appeared to be expanded. It is noteworthy that electron microscopy revealed marked poikilocytosis and Heinz body formation in red blood cells (RBCs) in both the sinus and cord. Histiocytes were swollen by a granular substance in the cytoplasm and also many secondary lysosomes. These morphological findings indicate that degradation of damaged RBCs induced by exposure to Cd might be promoted in the spleen and possibly cause splenomegaly. This RBC damage-hemolysis-splenomegaly sequence is also considered to be associated with the etiology of Cd-induced anemia. In addition to the abnormal RBC degradation, nuclei of lymphocytes in the Cd-exposed spleen exhibited high electron density, consistent with a preapoptotic state suggesting the immunosuppressive effect of Cd.

Hepatitis C virus NS5A protein is phosphorylated in vitro by a stably bound protein kinase from HeLa cells and by cAMP-dependent protein kinase A-alpha catalytic subunit

Hepatitis C virus (HCV) has a positive-strand RNA genome that codes for a polyprotein precursor, which is processed co- and post-translationally by cellular and viral proteinases into three structural and at least six non-structural (NS) proteins. The NS5A protein, expressed in mammalian cells, exists in two phosphorylated forms of 56-kDa and 58-kDa. In this study, we provide evidence for a stable association between NS5A and a protein kinase from HeLa cells and hepatocellular carcinoma (HepG2) cells by co-immunoprecipitation and by affinity to immobilized glutathione-S-transferase (GST)-NS5A fusion protein produced in E. coli. This protein kinase could phosphorylate in vitro the native NS5A on serine residues, (GST)-NS5A, histone H1, and casein as substrates. In addition, the GST-NS5A was also phosphorylated in vitro by the cAMP-dependent protein kinase A-alpha catalytic subunit.

[Matrix metalloproteinases]

Matrix-degrading enzymes, matrix metalloproteinases, are members of a unique family of Zinc-binding endopeptidases that are responsible for the metabolism of extracellular components in the tissue stroma. Their controlled expression is essential for normal processes such as wound healing and tissue remodeling, including embryogenesis. However, in many pathological conditions and events such as metastasis of malignant tumors and rheumatoid arthritis, the uncontrolled expression is evident.

The amino terminal deletion mutants of hepatitis C virus nonstructural protein NS5A function as transcriptional activators in yeast

To investigate the biological function of hepatitis C virus (HCV)-NS5A, the NS5A was fused at its N-terminus with the DNA binding domain (DBD) of yeast transcriptional activator GAL4 (GAL4-DBD). The GAL4-DBD alone had no transcriptional activation function. However, a mutant of the GAL4-DBD/NS5A fusion protein, in which 129 amino acid residues were deleted from the N-terminus of NS5A, exhibited strong transcriptional activation in yeast cells, bearing the Escherichia coli lacZ reporter gene encoding the beta-galactosidase under the transcriptional control of GAL4 promoter and TATA box. Further mutational analysis of NS5A revealed that the region between the amino acid residues 130 to 352 were critical for optimal level of transactivation. This region includes two acidic domains and one proline-rich region which have been shown to be involved in the function of several transcriptional activators.

Expression of stem cell factor in human aortic endothelial and smooth muscle cells

It has been confirmed that the receptor protein encoded by the c-kit proto-oncogene is expressed by cells of the hematopoietic, gonadal, pigment, and mast cell lineages and that its ligand, stem cell factor (SCF), is mainly expressed in their microenvironment. In a previous study we investigated the expression of the c-kit gene in human aortic endothelial cells (EC). In the present study we investigated the expression of SCF in human aortic EC and smooth muscle cells (SMC). Reverse transcription (RT)-PCR and Northern blot analyses showed that both human arterial EC and SMC expressed mRNA specific for the SCF gene. In addition, tissue-specific expression of the SCF gene was confirmed by in situ hybridization in the EC and the SMC. Western blot analysis and immunocytochemistry showed evidence of production of SCF protein in both the EC and the SMC. These results indicate the existence of mast cell-SMC interaction and of an autocrine loop of c-kit and its ligand on the surface of EC, suggesting that the interaction between c-kit protein and SCF may play an important role in metabolism of arterial wall and in the pathogenesis of atherosclerosis in the arterial intima.

Phenotypes of human esophageal squamous cell carcinoma based on matrix metalloproteinase production

We investigated the effects of epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) on cell growth and on regulation of matrix metalloproteinases (MMPs) in four cell lines of human esophageal squamous cell carcinomas (TE8, TE9, TE10, and TE11). EGF stimulated the production of proforms of gelatinase B (MMP-9) by three cell lines that could synthesize EGF by themselves, with TE9 being the exception. Particularly, both the production of MMP-9 and DNA synthesis in TE10 were stimulated significantly by EGF. TGF-beta slightly stimulated DNA synthesis in two cell lines, TE9 and TE11, and TGF-beta secretion by TE9 was detected. The production of proforms of gelatinases A (MMP-2) and MMP-9 was gradually induced by TGF-beta in a concentration-dependent manner in all the cell lines except for TE9. Flow cytometric analysis revealed that all the lines expressed both EGF- and TGF-beta-receptors. In conclusion, our present results indicate that at least there are possibly two distinct phenotypes in human esophageal squamous cell carcinoma: one (TE10) depends on autocrine EGF production that enhances DNA synthesis and MMP-9 production; and the other (TE9) on autocrine TGF-beta that stimulates DNA synthesis but not in relation to gelatinase production.

Apoptosis induced by cadmium

Cell death resulting from cadmium (Cd) intoxication has been confirmed to occur through apoptosis by morphological and biochemical studies. However it is still not clear whether Cd itself or metallothionein (MT) induced by Cd is the major factor responsible for the apoptosis. Although apoptosis is inducible by exposure of cells to various stimuli, the common pathway involved is generally accepted to be activation of endonucleases that induce internucleosomal cleavage of DNA, resulting in the 'ladder' formation observed upon agarose gel electrophoresis and the chromatin condensation seen by electron microscopy. Cd does not seem to activate the endonuclease in vitro. However, Cd itself can be associated with apoptosis through indirect oxidative stress by inhibition of antioxidant enzymes and possible interaction with zinc finger protein. In addition to the direct effect of Cd, MT appears to play dual roles in apoptosis induction: one as a Cd carrier by which Cd accumulates in the nucleus, and the other as an inhibitor of zinc finger proteins, which include transcriptional factors related to apoptosis such as the product of the apoptosis resistance gene A20. In this review, we demonstrated that the mode of cell death following Cd exposure is associated with intracellular movement of Cd and MT. A possible mechanism for Cd-induced apoptosis is also discussed.

Characterization of the nuclear localization signal and subcellular distribution of hepatitis C virus nonstructural protein NS5A

Hepatitis C virus (HCV) has a positive strand RNA genome that codes for a polyprotein that is processed co-translationally and post-translationally into three structural and at least seven nonstructural (NS) proteins. To investigate the function of NS5A, a recombinant vaccinia virus was constructed in which the NS5A gene was cloned under the control of T7 promoter and encephalomyocarditis virus 5'-untranslated region (EMCV-UTR) for cap-independent translation in mammalian cells. In addition, the NS5A gene was also cloned under the control of cytomegalovirus (CMV) early promoter. The NS5A expressed in monkey kidney (CV-1) cells was located predominantly in the cytoplasm. Using immunohistochemical analysis, the subcellular distribution of NS5A in liver biopsy samples from chronic HCV-infected patients was also found to be in the cytoplasm. However, the NS5A protein has a stretch of positively charged domain in the vicinity of proline and valine residues, (PPRKKRTVV), characteristic of a nuclear localization signal (NLS), in the COOH-terminal half of the protein. To investigate whether the putative NLS of NS5A is functional, chimeric expression plasmids were constructed in which regions containing the NLS were fused to the N-terminus of the E. coli beta-galactosidase (E. coli beta-Gal). The expression of the fusion proteins in CV-1 cells resulted in their nuclear localization, indicating that the putative NLS is functional in targeting the heterologous protein, E. coli beta-Gal, to the nucleus, although the native NS5A is retained in the cytoplasm.

Morphological and biochemical evidence for apoptosis in the terminal hypertrophic chondrocytes of the growth plate

The purpose of this study was to investigate the mechanism of cell death in chondrocytes of the growth plate. In the degenerative chondrocyte zone of the growth plate, apoptotic chondrocytes were defeated by the in situ nick end labelling method, by DNA analysis in agarose gel, and by electron microscopy. The results of the in situ nick end labelling method and the occurrence of a ladder pattern of DNA in agarose gel analysis indicated the activation of endogenous endonucleases, resulting in DNA fragmentation. Electron micrographs showed the early morphological changes associated with apoptosis. This report presents both morphological and biochemical evidence for apoptosis in the terminal hypertrophic chondrocytes of the growth plate. These data suggest that apoptosis of degenerative chondrocytes may play an important role in the control of normal and pathological endochondral ossification.

Interleukin-4 stimulates rheumatoid synovial fibroblasts to express matrix metalloproteinase-1 (tissue collagenase) and histamine H1 receptor mRNA

In the present study, we investigated the effect of interleukin-4 (IL-4) on metalloproteinase 1 (MMP-1/tissue collagenase) production in human rheumatoid synovial fibroblasts. Northern blot analysis revealed that addition of IL-4 with or without histamine stimulated the cells to increase the amount of proMMP-1 mRNA, and the IL-4 with histamine addition resulted in a 3.3-fold increase compared with histamine only. Furthermore, IL-4 itself stimulated the expression of histamine H1 receptor mRNA. These results suggest that IL-4 may play an important role in joint destruction in RA.