Molecular characterization of three rat liver serine-protease inhibitors affected by inflammation and hypophysectomy. Protein and mRNA analysis and cDNA cloning

Effects of vitamin E on pathological changes induced by diabetes in rat lungs

Twenty-fourmale rats were divided into three groups: Control (C), non-treated diabetic (NTD), and vitamin E-treated diabetic (VETD) groups. After 6 weeks, we evaluated the changes in the alveolar epithelium, alveolar septum thickness, Hcy, and cathepsin G levels in the lung tissue and plasma serine protease inhibitor levels.The results revealed a significant increase in alveolar septum thickness, a high number of type II pneumocytes, high number of glycogen granules, increased vascular elastic membrane thickness, and increased Hcy and cathepsin G levels in the diabetic rats. Plasma level of serine protease inhibitors showed a significant decrease in the NTD animals. The vitamin E-treated rats showed significant amelioration of lung tissue changes, as well as restoration of high cathepsin G, Hcy levels, and serine protease inhibitors when compared to the control rats. These results suggest that diabetes induces lung tissue changes that may be stimulated by Hcy and cathepsin G mediated oxidative stress by, and protective effect could be achieved by using vitamin E.

Combined age- and trauma-related proteomic changes in rat neocortex: a basis for brain vulnerability

This proteomic study investigates the widely observed clinical phenomenon, that after comparable brain injuries, geriatric patients fare worse and recover less cognitive and neurologic function than younger victims. Utilizing a rat traumatic brain injury model, sham surgery or a neocortical contusion was induced in 3 age groups. Geriatric (21 months) rats performed worse on behavioral measures than young adults (12-16 weeks) and juveniles (5-6 weeks). Motor coordination and certain cognitive deficits showed age-dependence both before and after injury. Brain proteins were analyzed using silver-stained two-dimensional electrophoresis gels. Spot volume changes (>2-fold change, p<0.01) were identified between age and injury groups using computer-assisted densitometry. Sequences were determined by mass spectrometry of tryptic peptides. The 19 spots identified represented 13 different genes that fell into 4 general age- and injury-dependent expression patterns. Fifteen isoforms changed differentially with respect to both age and injury (p<0.05). Further investigations into the nature and function of these isoforms may yield insights into the vulnerability of older patients and resilience of younger patients in recovery after brain injuries.

Altered expression of securin (Pttg1) and serpina3n in the auditory system of hearing-impaired Tff3-deficient mice

INTRODUCTION

Tff3 peptide exerts important functions in cytoprotection and restitution of the gastrointestinal (GI) tract epithelia. Moreover, its presence in the rodent inner ear and involvement in the hearing process was demonstrated recently. However, its role in the auditory system still remains elusive. Our previous results showed a deterioration of hearing with age in Tff3-deficient animals.

RESULTS

Present detailed analysis of auditory brain stem response (ABR) measurements and immunohistochemical study of selected functional proteins indicated a normal function and phenotype of the cochlea in Tff3 mutants. However, a microarray-based screening of tissue derived from the auditory central nervous system revealed an alteration of securin (Pttg1) and serpina3n expression between wild-type and Tff3 knock-out animals. This was confirmed by qRT-PCR, immunostaining and western blots.

CONCLUSIONS

We found highly down-regulated Pttg1 and up-regulated serpina3n expression as a consequence of genetically deleting Tff3 in mice, indicating a potential role of these factors during the development of presbyacusis.

Vitamin B6 suppresses serine protease inhibitor 3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells

SCOPE

Previous reports in the areas of animal studies and, recently epidemiology, have linked anti-tumorigenic and anti-inflammatory effects to dietary vitamin B6. This study investigated the molecular mechanism of these effects of vitamin B6.

METHODS AND RESULTS

DNA microarray analysis was used to obtain information on changes in colon gene expression from vitamin B6 (pyridoxine) repletion in vitamin B6-deficient rats. Pyridoxine supplementation down-regulated the inflammatory molecule, serine protease inhibitor clade A member 3 (SPI-3) mRNA expression in the colon. This study also showed that tumor necrosis factor α (TNF-α) induced SPI-3 mRNA expression in HT-29 human colon cancer cells, and vitamin B6 (pyridoxal hydrochloride) pretreatment of HT-29 cells inhibited TNF -induced mRNA expression of SPI-3. Vitamin B6 inhibited TNF-α-induced NF-κB activation via suppression of IκBα degradation in HT-29 cells. HT-29 cells stably expressing epitope-tagged ubiquitin were generated and vitamin B6 pretreatment was shown to inhibit ubiquitination of the IkB protein in response to TNF-α-i.

CONCLUSION

Vitamin B6 suppressed SPI-3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells. Further, this study showed a possible role of vitamin B6 in the regulation of protein ubiquitination.

Molecular signature of mineralocorticoid receptor signaling in cardiomyocytes: from cultured cells to mouse heart

Excess mineralocorticoid signaling is deleterious for cardiovascular functions, as demonstrated by the beneficial effects of mineralocorticoid receptor (MR) antagonism on morbidity and mortality in patients with heart failure. However, the understanding of signaling pathways after MR activation in the heart remains limited. We performed transcriptomic analyses in the heart of double-transgenic mice with conditional, cardiomyocyte-specific, overexpression of the MR (MRcardio mice) or the glucocorticoid receptor (GR; GRcardio mice). Some of the genes induced in MRcardio mice were selected for comparative evaluation (real time PCR) in vivo in the heart of mice and ex vivo in the MR-expressing cardiomyocyte H9C2 cell line after aldosterone or corticosterone treatment. We demonstrate that chronic MR overexpression in the heart results in a limited number of induced (n = 24) and repressed (n = 22) genes compared with their control littermates. These genes are specifically modulated by MR because there is limited overlap (three induced, four repressed) with the genes that are regulated in the heart of GRcardio mice (compared with control mice: 70 induced, 73 repressed). Interestingly, some MR-induced genes that are up-regulated in vivo in mice are also induced by 24-h aldosterone treatment in H9C2 cells, such as plasminogen activator inhibitor 1 and Serpina-3 (alpha1-antichymotrypsin). The signaling pathways that are affected by long-term activation of MR may be of particular interest to design novel therapeutic targets in cardiac diseases.

Alpha 1-antichymotrypsin/SerpinA3 is a novel target of orphan nuclear receptor Nur77

Nur77 is one member of the nuclear receptor superfamily. As a transcription factor, Nur77 participates in a variety of biological processes, including T cell development, inflammatory responses, steroid hormone synthesis, and hepatic glucose metabolism. It typically acts via binding to the Nur77 responsive element (NBRE) in the promoter regions of its target genes. In the present study, we identified a novel Nur77-regulated gene, alpha1-antichymotrypsin/SerpinA3, via an approach combining computational prediction and wet-laboratory validations. First, we identified 483 candidate genes via a human genome-wide scan for NBREs in their proximal promoters. Three out of 14 function-associated genes were further identified to be transactivated by Nur77 in luciferase reporter gene assays in HEK 293T cells. The transactivation assay proved that the NBRE (-182 to -175) in the SerpinA3 promoter region is a novel Nur77-dependent functional motif in HEK 293T and HepG2 cells. Electrophoretic mobility shift and chromatin immunoprecipitation assays demonstrated that Nur77 physically associates with the SerpinA3 promoter region both in vitro and in vivo. Nur77 overexpression and RNA interference-mediated Nur77 gene knockdown analysis confirmed that SerpinA3 is indeed a novel Nur77-targeted gene. These data may throw light on the function of Nur77 in inflammatory responses and acute-phase reactions as well as the development of Alzheimer's disease.

Role of glypican-1 in the trophic activity on PC12 cells induced by cultured sciatic nerve conditioned medium: identification of a glypican-1-neuregulin complex

Glypican-1 is an extracellular matrix component found by microsequencing in a medium conditioned by cultured rat-sciatic nerves (CM). This CM was concentrated by ultrafiltration and fractionated by quaternary ammonium chromatography, followed by Hi-Trap blue affinity chromatography to obtain the active fraction B1.2. Previously, we have reported a 54 kDa neuregulin (NRG) in the same B1.2 fraction [Villegas et al., Brain Res. 852 (2001) 304]. The effect of Glypican-1 on the neuron-like differentiation of PC12 cells was investigated by immunoprecipitation, Western blot and cellular image analysis. Removal of glypican-1 by immunoprecipitation with increasing concentrations of specific antibodies revealed a gradual decrease of the differentiation activity of fraction B1.2, which paralleled the results obtained by removal of the 54 kDa NRG protein. Colorless native electrophoresis and Western blot analysis was used to identify a glypican-1-NRG protein complex, which could be afterwards separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis into its individual components. Additionally, it was demonstrated that glypican-1, in cooperation with the 54 kDa NRG, is involved in the neuronal-like differentiation of PC12 cells and could play an important role on the regeneration responses of peripheral nerves.

Inflammation induces serine protease inhibitor 3 expression in the rat pineal gland

In the rat pineal gland, prominent expression of serine protease inhibitor 3 (SPI-3) mRNA is seen after systemic injection of lipopolysaccharide. The up-regulation of SPI-3 mRNA expression is also confirmed by northern blotting. Most SPI-3 mRNA-positive cells simultaneously express synaptophysin, a marker for pinealocytes, but not glial fibrillary acidic protein, a marker for astrocytes. This indicates that SPI-3 mRNA-positive cells are pinealocytes. Almost all SPI-3 mRNA-positive cells also showed translocation of the signal transducers and activators of transcription 3 (STAT3) into nuclei after lipopolysaccharide injection. These data support previous in vitro results that SPI-3 expression is induced in a STAT3-mediated manner. In addition, the expression of ciliary neurotrophic factor receptor (CNTFR) and leukemia inhibitory factor receptor (LIFR) mRNAs, but not of interleukin 6 receptor mRNA, was up-regulated after systemic lipopolysaccharide treatment. Because these receptors are upstream of STAT3, the present results suggest that cytokines such as LIF and/or CNTF induce SPI-3 expression via STAT3 in the pineal gland in response to inflammatory stimulus. We conclude that although the functional consequences of SPI-3 in the pineal gland during systemic inflammation are unknown, SPI-3 may have a crucial role in preventing some degenerative proteolysis induced by inflammatory stimuli.

Monitoring the effects of drug treatment in rat models of disease by serum protein analysis

In this review we list from literature investigations on rat serum proteins using electrophoretic techniques in connection with drug testing. From our own research work, we provide annotated two-dimensional maps of rat serum proteins under control and experimental conditions. Emphasis is on species-specific components and on the effects of acute and chronic inflammation. We discuss our project of structural proteomics on rat serum as a minimally invasive approach to pharmacological investigation, and we outline a typical experimental plan for drug testing according to the above guidelines. We then report in detail on the results of our trials of anti-inflammatory drugs on adjuvant arthritis, an animal model of disease resembling in many aspects human rheumatoid arthritis. We demonstrate a correlation between biochemical parameters and therapeutic findings and outline the advantages of the chosen methodological approach, which proved also sensitive in revealing "side effects" of the test drugs. In an appendix we describe our experimental protocol when performing two-dimensional electrophoresis of rat serum.

Proteomic analysis of rat kidney cortex following treatment with gentamicin

The regionally specific structure and function of the kidney renders it susceptible to toxic exposure. To characterize these changes at the proteome level, we have investigated the effects on protein expression following treatment with gentamicin. The more than 20 proteins identified were involved in the citric acid cycle, gluconeogenesis, fatty acid synthesis, and transport or cellular stress responses. These results strongly support the notion that energy production is impaired and mitochondrial dysfunction is involved in gentamicin-induced nephrotoxicity.

Effect of selenium and vitamin E deficiency on differential gene expression in rat liver

To examine the molecular events associated with selenium (Se) and vitamin E (VE) deficiency, we applied cDNA array technology to define the transcriptional response in the liver of Se- and VE-deficient rats. VE deficiency alone did not induce any significant changes in expression profile among the genes evaluated. Se deficiency lead to a down-regulation of Se-dependent cGPx and to an induction of genes, encoding for detoxifying enzymes in liver (cytochrome P450 4B1, UDP-glucuronosyltransferase 1). Combined VE and Se deficiency was characterized by alterations in the expression level of genes encoding for proteins involved in inflammation (multispecific organic anion exporter, SPI-3 serine protease inhibitor) and acute phase response (alpha-1 acid glycoprotein, metallothionein 1). Additionally, a significant down-regulation in the expression level of genes important in the inhibition of apoptosis (defender against cell death 1 protein, Bcl2-L1), cell cycle (G1/S-specific cyclin D1) and antioxidant defense (gamma-glutamylcysteine synthetase catalytic subunit) was demonstrated. The experimental strategy identified several novel Se and VE sensitive genes.

Inhibition of growth hormone action in models of inflammation

Growth hormone (GH) action is attenuated during the hepatic acute-phase response (APR). To understand this attenuation, we asked whether GH and cytokine-signaling pathways intersect during an APR. In hypophysectomized rats treated with lipopolysaccharide (LPS), accumulation of activated signal transducer and transcription activator 5 (Stat5) in hepatic nuclei in response to GH and its binding to a GH response element (GHRE) from the serine protease inhibitor (Spi) 2.1 promoter are diminished in a time-dependent manner. Similarly, accumulation of activated Stat3 in hepatic nuclei in response to LPS and its binding to a high-affinity sis-inducible element (SIE) are also diminished by the simultaneous administration of GH. In functional assays with primary hepatocytes, LPS-stimulated monocyte-conditioned medium (MoCM) inhibits the GH response of Stat5-dependent Spi 2.1 reporter activity but induces Stat3-dependent Spi 2.2 reporter activity, as in an APR. Similar results are obtained when hepatocytes are treated with either tumor necrosis factor-alpha (TNF-alpha) or interleukin (IL)-1beta. TNF-alpha, IL-1beta, and IL-6 also inhibit GH-induced Spi 2.1 mRNA expression in hepatocytes. Thus inhibition of the GH signaling pathway during an APR results in reduced expression of GH-responsive genes.

Purification and cloning of type A/B hnRNP proteins involved in transcriptional activation from the Rat spi 2 gene GAGA box

The GAGA box of the rat serine protease inhibitor 2 (spi 2) genes not only acts as a basal promoter element, but also mediates transcriptional activation by growth hormone and interleukin-6. The GAGA box is separated from the TATA box by only 12 bp, and this close association is required for efficient transcription. Hence, the GAGA box may influence transcription efficiency through interactions between GAGA box binding proteins and some components of the RNA polymerase II complex. Here we report the cloning of two GAGA box-binding proteins termed p38 and p40, that belong to the type A/B heterogeneous nuclear ribonucleoprotein subgroup. GAGA box mutations that diminish the affinity for p38 and p40 decrease basal and GH-induced reporter gene expression. Furthermore, nuclear extracts depleted of p38 and p40 can no longer support GAGA box-dependent in vitro transcription. Therefore, two polypeptides previously assigned to a family of RNA processing proteins also act as DNA-binding, promoter-specific transcription factors.

Profiling of genes which are differentially expressed in mouse liver in response to adenoviral vectors and delivered genes

The effects of transgene delivery by adenoviral vectors were studied by probing a 588 gene, mouse cDNA array with mRNA derived from infected liver. The liver tissues were obtained from naive mice and mice infected with replication-deficient adenovirus, adenovirus expressing transforming growth factor beta1 (TGFbeta1), and adenovirus expressing connective tissue growth factor (CTGF). Expression of 98 genes was detected in the array analysis. The increased expression of the transcripts for Stat1, gamma interferon-induced monokine (MIG) and interferon regulatory factor 1 (IRF1) clearly demonstrated the immune response induced by infection with a first generation, replication-incompetent adenovirus. In vivo expression of TGFbeta1 led to a down-regulation of genes involved in the immune response. The increased expression of u-PAR1, laminin receptor and BMP-1 confirms the importance of CTGF and TGFbeta1 in angiogenesis, and tissue repair. Expression of the serine protease inhibitors, Spi 2.4 and Spi 2, is also increased in response to AdTGFbeta1 and AdCTGF.

IL-1beta induces serine protease inhibitor 3 (SPI-3) gene expression in rat pancreatic beta-cells. Detection by differential display of messenger RNA

Immune-mediated beta-cell damage induces diverse intracellular signals, leading to transcription of different genes which may either contribute to beta-cell repair and/or defence or lead to cell death. The cytokine interleukin-1beta (IL-1) is a potential mediator of beta-cell dysfunction and damage in type 1 diabetes mellitus. To understand the molecular actions of this cytokine upon beta-cells, this study aimed at the cloning of genes induced in FACS-purified rat pancreatic beta-cells by a 6- or 24-h exposure to IL-1 by using differential display of mRNA with reverse transcription-polymerase chain reaction (DDRT-PCR). Among these cytokine-induced genes, a gene encoding for rat serine protease inhibitor (SPI-3) was isolated. SPI-3 may be involved in cellular defence responses against inflammatory stress. RT-PCR analysis confirmed that SPI-3 mRNA expression in rat beta-cells is increased by IL-1 at an early stage (2 h), with maximal accumulation during 6-12 h and decline after 24 h. Similar observations were made in mouse pancreatic islets and in the rat insulinoma cell line RINm5F. IFN-gamma neither increased SPI-3 gene expression nor potentiated its induction by IL-1 in rat beta-cells. The stimulatory effects of IL-1 on SPI-3 mRNA expression were decreased by co-incubation with an inhibitor of gene transcription (actinomycin D), an inhibitor of protein synthesis (cycloheximide) or an inhibitor of NF-kappaB activation (PDTC). On the other hand, a blocker of inducible nitric oxide synthase (iNOS) activity (N(G)-methyl-L-arginine) did not prevent IL-1-induced SPI-3 expression. Thus, SPI-3 mRNA expression following IL-1 exposure depends on gene transcription, protein synthesis and activation of the nuclear transcription factor NF-kappaB, but it is independent of NO formation.

Regulation of Spi 2.1 and 2.2 gene expression after turpentine inflammation: discordant responses to IL-6

The rat serine protease inhibitor (Spi) 2 gene family includes both positive (Spi 2.2) and negative (Spi 2.1) acute phase reactants, facilitating modeling of regulation of hepatic acute phase response (APR). To examine the role of signal transducer and activation of transcription (STAT) proteins in the divergent regulation of these model genes after induction of APR, we evaluated the proximal promoters of the genes, focusing on STAT binding sites contained in these promoter elements. Induction of APR by turpentine injection includes activation of a STAT3 complex that can bind to a gamma-activated sequence (GAS) in the Spi 2.2 gene promoter, although the Spi 2.2 GAS site can bind STAT1 or STAT5 as well. To create an in vitro model of APR, primary hepatocytes were treated with combinations of cytokines and hormones to mimic the hormonal milieu of the whole animal after APR induction. Incubation of primary rat hepatocytes with interleukin (IL)-6, a critical APR cytokine, leads to activation of STAT3 and a 28-fold induction of a chloramphenicol acetyltransferase reporter construct containing the -319 to +85 region of the Spi 2.2 promoter. This suggests the turpentine-induced increase of Spi 2.2 is mediated primarily by IL-6. In contrast, although turpentine treatment reduces Spi 2.1 mRNA in vivo and IL-6 does not increase Spi 2.1 mRNA in primary rat hepatocytes, treatment of hepatocytes with IL-6 results in a 5. 4-fold induction of Spi 2.1 promoter activity mediated through the paired GAS elements in this promoter. Differential regulation of Spi 2.1 and 2.2 genes is due in part to differences in the promoters of these genes at the GAS sites. IL-6 alone fails to reproduce the pattern of rat Spi 2 gene expression that results from turpentine-induced inflammation.

Proteins of rat serum: III. Gender-related differences in protein concentration under baseline conditions and upon experimental inflammation as evaluated by two-dimensional electrophoresis

We have previously described the major components of rat serum (Electrophoresis 1998, 19, 1484-1492 and 1493-1500). In this report we examine sex-related differences in protein concentrations, both in control animals and upon experimentally induced inflammation. Under baseline conditions approximately one third of the spots resolved in serum by two-dimensional electrophoresis (2-DE) are expressed at levels > or =25% higher in female rats than in male rats and a further 10% at levels > or =25% lower. Inflammation increases the expression of the positive acute-phase reactants: hemopexin, ceruloplasmin, alpha1-antitrypsin (all approximately 2-fold), C-reactive protein (3- to 5-fold), serine protease inhibitor-3 (4- to 5-fold), thiostatin (> 5-fold in females, >20-fold in males), clusterin, orosomucoid, haptoglobin chains and alpha2-macroglobulin. The baseline level of the last four markers is below the detection limit, hence no percent increase can be computed. Conversely, negative acute-phase reactants are reduced on inflammation: alpha1-inhibitor III, alpha2-HS-glycoprotein, kallikrein-binding protein and transthyretin (all reduced to between 1/2 to 1/3 of the baseline levels), retinol-binding protein (to about 1/2 to 1/4) and albumin (to 2/3). Except for thiostatin, the changes in acute-phase protein levels are similar in male and female rats.

Growth hormone inhibits rat liver alpha-1-acid glycoprotein gene expression in vivo and in vitro

The gene encoding alpha-1-acid glycoprotein (AGP), one of the major acute-phase proteins, is positively controlled at the transcriptional level by cytokines (interleukin-1 [IL-1], IL-6, and tumor necrosis factor alpha) and glucocorticoids. Here, we show that growth hormone (GH) treatment of isolated rat hepatocytes in vitro reduces AGP messenger RNA (mRNA) expression. AGP gene expression remained inducible by IL-1, IL-6, and phenobarbital (PB) in GH-treated hepatocytes. Interestingly, the repressive effect of GH on AGP gene expression was also observed in vivo: liver AGP mRNA content was strongly increased in hypophysectomized rats, and GH treatment of these animals led to a decrease in mRNA to levels lower than those in untreated control animals. Moreover, the inhibitory effect of GH mainly occurs at the transcriptional level and can be observed as little as 0.5 hours after GH adding in vitro to isolated hepatocytes. These results show negative regulation of AGP gene expression and strongly suggest that GH is a major endogenous regulator of constitutive AGP gene expression. Moreover, transfection assays showed that the region of the AGP promoter located at position -147 to -123 is involved in AGP gene regulation by GH. Furthermore, GH deeply modifies the pattern of nuclear protein binding to this region. GH treatment of hypophysectomized rats led to the release of proteins of 42 to 45 and 80 kd and to the binding of proteins of 48 to 50 and 90 kd.

Proteins of rat serum: II. Influence of some biological parameters of the two-dimensional electrophoresis pattern

This report complements the database already detailed for serum proteins of healthy adult male rats (P. Haynes et al., Electrophoresis 1998, 19, 1484-1492). The influence on the two-dimensional electrophoresis (2-DE) pattern of certain physiological conditions (sex, age) was studied as well as of changes in thyroid metabolism. We have extended the information about the major components of rat serum by identifying the proteins typical for the response to acute inflammation. Analyzing 27 spots, six proteins not found in control sera could be recognized; migration at overlapping or close positions with five already characterized proteins was observed for some. A compilation of all our rat data can be accessed through: http://weber.u.washington.edu/ruedilab/ aebersold.html.

Transcription of the rat serine protease inhibitor 2.1 gene in vivo: correlation with GAGA box promoter occupancy and mechanism of cytokine-mediated down-regulation

Two GH-response elements (GHREs) and a single glucocorticoid (GC)-response element were found to regulate activity of the rat serine protease inhibitor 2.1 gene (spi 2.1) promoter in vitro. To assess the physiological relevance of these observations, we have investigated the relationship existing between the level of spi 2.1 gene transcription, structural modifications of the chromatin, and in vivo nuclear protein-promoter interactions monitored by genomic footprinting, in control, hypophysectomized, and inflamed rats. We also addressed the mechanism of inflammation-mediated gene down-regulation. We found that a high level of spi 2.1 gene transcription correlates with hypersensitivity of the promoter to deoxyribonuclease I (DNase I) and maximal occupancy of the GAGA box (GHRE-I). The failure of GAGA-box binding proteins (GAGA-BPs) to interact with the GAGA box appears to result from an impairment in GH action due to its absence (i.e. hypophysectomized animals) or to the appearance of a cytokine-mediated GH-resistant state (i.e. inflamed rats) in liver. Unlike the GAGA box, signal transducer and activator of transcription (STAT) factor-binding sites included in the GHRE-II were never found to be protected against DNase I attack but displayed a differential DNase I reactivity depending on the level of gene transcription. Alterations in DNase I reactivity of the GC-response element region suggest that GC receptor-GC complexes may associate, in a transient manner, with the promoter in the actively transcribing control state. Taken together, our studies suggest a mechanism of spi 2.1 gene activation in vivo whereby the GH-dependent chromatin remodeling caused by or concomitant to the recruitment of GAGA-box binding proteins is the first compulsory and presumably predominant step.

Molecular cloning and expression of rat kallistatin gene

We have previously purified and cloned human kallistatin and rat kallikrein-binding protein (RKBP), which are tissue kallikrein inhibitors belonging to the serine proteinase inhibitor superfamily. In this study, we have cloned and sequenced the gene encoding rat kallistatin with Phe-Phe-Ser-Ala-Gln at positions P2-P3', which is identical to the reactive center of human kallistatin. Rat kallistatin is highly similar to human kallistatin, sharing 68% and 57% sequence identity at the cDNA and the amino acid levels. The rat kallistatin gene exists in a single copy and is located on chromosome 6. An SphI RFLP is found between SHR and WKY rats at or near the rat kallistatin gene locus. Two amino acid polymorphisms of the rat kallistatin gene between these two strains were found by sequence analysis. A candidate promoter in the 5'-flanking region (109 bp) of the rat kallistatin gene has been identified by reporter assays. The expression of rat kallistatin in the liver is growth-dependent and down-regulated during acute phase inflammation. Recombinant rat kallistatin produced in E. coli is able to bind to tissue kallikrein, and the interaction is inhibited by heparin. These characteristics define rat kallistatin as the counterpart of human kallistatin.

Tissue kallikrein-binding protein reduces blood pressure in transgenic mice

The kallikrein-kinin system participates in blood pressure regulation. One of the kallikrein-kinin system components, kallikrein-binding protein, binds to tissue kallikrein and inhibits its activity in vitro. To investigate potential roles of rat kallikrein-binding protein (RKBP) in vivo, we have developed transgenic mice that express an RKBP gene under the control of the mouse metallothionein metal-responsive promoter. Expression of the transgene, RKBP, was detected in the liver, kidney, lung, heart, pancreas, salivary glands, spleen, brain, testis, and adrenal gland at the mRNA and protein levels. Systolic blood pressures of homozygous transgenic mice were 88.5 +/- 0.8 mm Hg (mean +/- S.E., n = 19, P < 0.001) for one line and 88.8 +/- 1.6 mm Hg (mean +/- S.E., n = 19, P < 0.001) for another, as compared with 100.5 +/- 0.8 mm Hg (mean +/- S.E., n = 18) for control mice. Direct blood pressure measurements of these transgenic mice through an arterial cannula showed similar reductions of blood pressure. Intravenous injection of purified RKBP into mice via a catheter produced a dose-dependent reduction of the mean arterial blood pressure. Our findings suggest that RKBP may function as a vasodilator in vivo, independent of regulating the activity of tissue kallikrein.

Regulation of expression of the rat serine protease inhibitor 2.3 gene by glucocorticoids and interleukin-6. A complex and unusual interplay between positive and negative cis-acting elements

The rat serine protease inhibitor 2.3 gene (spi 2.3) is almost completely silent in normal animals and is transiently expressed during acute inflammation. It encodes a potential anti-elastase which is likely to play a major physiological role for the host defense. Two well-known inflammatory mediators, glucocorticoids and interleukin-6 (IL-6) activate the spi 2.3 promoter and increase steady-state levels of mRNA in cultured hepatocytes. GC activation is mediated by a single glucocorticoid-response element which seems to act autonomously. A unique array of four functional IL-6-response sites was identified in the spi 2.3 promoter. Three of them (C-II--IV) bear structural identity to the CCAAT/enhancer-binding-protein-binding site consensus sequence, whereas the fourth closely resembles the consensus kappa B nuclear factor recognition motif. The C-IV element, which is the most active, contains the motif 5'-CTGGGA and binds the IL-6-inducible acute-phase response factor present in liver nuclear extracts from inflamed rats. Both basal and IL-6-dependent activities of each individual cytokine-response element tested separately are strongly down regulated by a recently identified regulatory sequence, located in the 3' untranslated region of the spi 2.3 gene. However, this repressor element does not significantly affect overall IL-6-dependent spi 2.3 promoter activity. This suggests that, in the context of the active gene in vivo, all four IL-6-response sites, which are largely redundant, cooperate to overcome the strong repressive effect of the 3' untranslated region silencer and are needed to bring about a maximal IL-6 response. These data reveal a novel type of regulation of an acute-phase gene involving different classes of IL-6-response elements controlled by a repressor and acting in conjunction with a glucocorticoid-response element.

Induction of SPI-3 mRNA, encoding a serine protease inhibitor, in gerbil hippocampus after transient forebrain ischemia

We cloned genes the expression of which is induced in the Mongolian gerbil (Meriones unguiculatus) hippocampus after transient forebrain ischemia by a differential display technique. Among these genes, a rat serine protease inhibitor SPI-3 homologue was isolated. Present analyses suggested that the expression of gerbil SPI-3 mRNA was closely associated with delayed neuronal death and may block activities of proteases leaking from degenerating neurons or may support neuronal survival.

Isolation of cDNA encoding a novel serpin of crayfish hemocytes

We have cloned a serpin-type proteinase inhibitor from a crayfish hemocyte cDNA library. The deduced amino acid sequence consists of 429 amino acids with a putative signal peptide of 21 amino acids. The mature protein has a calculated molecular mass of 45,029 daltons. Identities ranging up to 38% were observed between the crayfish serpin and other members of the serpin family. Phylogenetic analysis shows that the crayfish serpin has a closer relationship to insect serpins than to other animal serpins. Phe369-Ser370 were proposed to be the P1-P1' residues of the inhibitor reactive site. This protein was found to be expressed in hemocytes but not in the hepatopancreas of the crayfish Pacifastacus leniusculus.

The primary elastase inhibitor (elastasin) and trypsin inhibitor (contrapsin) in the goat are serpins related to human alpha 1-anti-chymotrypsin

Two primary serine proteinase inhibitors in goat plasma have been isolated and characterized. The N-terminal sequence analysis of the purified proteins revealed that they are closely related to each other and are highly homologous to human alpha 1-anti-chymotrypsin rather than alpha 1-proteinase inhibitor. However, despite structural similarities the inhibitory specificity of the goat inhibitors differed from each other and from that of anti-chymotrypsin. In contrast with human anti-chymotrypsin, one of the goat inhibitors was shown to be a strong and specific inhibitor of trypsin (k(ass.) = 1.9 x 10(6) M-1.s-1), whereas the other was an efficient inhibitor of neutrophil elastase (k(ass.) = 1.5 x 10(6) M-1.S-1). Differences in the inhibitory specificity of each protein could readily be attributed to the amino acid sequence within the reactive site region. The trypsin inhibitor with an assumed arginine residue at the P1 position of the reactive-site peptide bond is referred to as 'contrapsin', and indicates that the occurrence of contrapsins is not restricted to rodents. In contrast, the inhibitory specificity, resistance to oxidative and proteolytic inactivation and the presence of a P1 leucine residue in the elastase inhibitor is unique among inhibitory serpins that have been characterized to date. Because this serpin is apparently the major elastase inhibitor in goat plasma, it is likely to be involved in the control of goat neutrophil elastase. Therefore, we suggest the name 'elastasin', and extend it to any other anti-chymotrypsin related serpins possessing neutrophil-elastase- inhibitory activity.

Hepatocyte growth factor and retinoic acid exert opposite effects on synthesis of type 1 and type 2 acute phase proteins in rat hepatoma cells

Rat hepatoma cells H-35 cultured in serum-free medium were exposed to interleukin-6 (IL-6), interleukin-1 (IL-1), hepatocyte growth factor (HGF), retinoic acid (RA), or a mixture of these factors. Production of acute phase proteins, responding to IL-6 alone (type 2) or to the mixture of IL-6 and IL-1, was assessed by electroimmunoassay and the corresponding mRNAs were compared by Northern blot analysis. HGF enhanced IL-6-induced synthesis of alpha-2-macroglobulin but reduced synthesis of C3 complement and alpha-1-acid glycoprotein. Retinoic acid reduced the response to IL-6 of alpha-2-macroglobulin but enhanced that of alpha-1-acid glycoprotein and especially of C3 complement. In general, changes in protein secretion were correlated with the contents of their corresponding cellular mRNAs. These results indicate that hepatocyte growth factor can enhance basal or IL-6-induced gene expression of type 2 and reduce the expression of type 1 acute phase proteins, whereas the action of retinoic acid is opposite. The modulation of acute phase response by HGF and RA likely involves transcriptional factors and regulatory sequences in the genes coding for these two types of acute phase proteins.

Expression and characterization of rat kallikrein-binding protein in Escherichia coli

Rat kallikrein-binding protein is a novel serine-proteinase inhibitor that forms a covalent complex with tissue kallikrein. We have purified rat kallikrein-binding protein and cloned the cDNA and the gene encoding rat kallikrein-binding protein [Chao, Chai, Chen, Xiong, Chao, Woodley-Miller, Wang, Lu and Chao (1990) J. Biol. Chem. 265, 16394-16401; Chai, Ma, Murray, Chao and Chao (1991) J. Biol. Chem. 266, 16029-16036]. In the present study, we have expressed rat kallikrein-binding protein in Escherichia coli with a T7-polymerase/promoter expression system. A high level of expression was detected by an e.l.i.s.a. with an average of 24.2 mg of recombinant rat kallikrein-binding protein per 1 of culture. The recombinant protein appeared as a major protein in a crude extract of Escherichia coli on SDS/PAGE. It showed a molecular mass of 43 kDa and was recognized by polyclonal antibody to the native rat kallikrein-binding protein in Western-blot analysis. The recombinant rat kallikrein-binding protein has been purified to apparent homogeneity by DEAE-Sepharose CL-6B, hydroxyapatite Bio-Gel HPHT and Mono P 5/5 column chromatography. The purified recombinant rat kallikrein-binding protein showed immunological identity with the native rat kallikrein-binding protein purified from rat serum, in a specific e.l.i.s.a. To confirm the fidelity of the expression, the N-terminal ten amino acids of the recombinant rat kallikrein-binding protein were sequenced and were shown to match perfectly with those of the native rat kallikrein-binding protein. The purified recombinant rat kallikrein-binding protein formed SDS- and heat-stable complexes with rat tissue kallikrein (rK1) and T-kininogenase (rK10) in vitro, but not with other enzymes in the rat kallikrein gene family, such as tonin (rK2) and S3 protein (rK9), which indicates enzyme-specific binding. The properties of the recombinant rat kallikrein-binding protein including its size, charge, complex formation with target enzymes and immunological characteristics were compared with those of the native protein. This expression system provides a simple way to obtain a large amount of the biologically active recombinant protein, to study structure-function relationships of the rat kallikrein-binding protein and its interaction with its target enzymes.

Molecular cloning of silkworm (Bombyx mori) antichymotrypsin. A new member of the serpin superfamily of proteins from insects

The cDNA of silkworm (Bombyx mori) antichymotrypsin (sw-Achy) was cloned from larval fat body and its nucleotide sequence was determined. The deduced amino acid sequence of mature sw-Achy begins with Phe1 and ends with Phe384, with a preceding 16-amino-acid signal peptide. The amino-acid sequence similarities of sw-Achy with the serine-proteinase inhibitors (serpins) silkworm antitrypsin, tobacco hornworm alaserpin, human alpha-1-antitrypsin and human alpha-1-antichymotrypsin were 29.6%, 30.3%, 26.1%, and 25.0%, respectively. The highly conserved amino acids in other serpins are also conserved in sw-Achy. sw-Achy is thought to be a new member of the serpin family. Multiple alignment of sw-Achy with 23 other kinds of serpin by the progressive method produced a phylogenetic tree in which all four insect serpins are grouped separately within one branch. The reactive site of sw-Achy with alpha-chymotrypsin was identified as Thr343-Ser344 by direct amino-acid sequence analysis of cleaved and purified protein.

Regulation of two rat serine-protease inhibitor gene promoters by somatotropin and glucocorticoids. Study with intact hepatocytes and cell-free systems

Only two out of the three serine-protease inhibitor genes (SPI 2.1, 2.2 and 2.3) expressed in rat liver are tightly controlled by somatotropin acting mainly at the transcriptional level, thus making this gene system particularly suitable to study its molecular mechanism of action. In these studies, we analyzed SPI promoter activities in cultured hepatocytes transfected by electroporation or in cell-free extracts. The proximal SPI 2.1 promoter region contains two somatotropin-responsive sites which are functional in intact cells. The more distal element that maps at positions -175 to -114, and is analogous to the one originally described by Yoon et al. (1990) [Yoon, J. B., Berry, S. A., Seelig, S. & Towle, H. C. (1990) J. Biol. Chem. 265, 19947-19954], behaves as a weak enhancer whose activity is strongly potentiated by proximal 5' downstream sequences that contains potential CCAAT-enhancer binding protein (C/EBP) sites. An additional proximal hormone-sensitive site is located in the close vicinity of the transcription-start site between positions -41 and +8, and also requires the first C/EBP-binding element to be active. The distal element appears to contribute more importantly (60%) than the proximal one (40%) to the overall somatotropin stimulation of chimeric gene expression. Nonetheless, both displayed similar dose-dependence, with half-maximal and maximal effects occurring at 0.5-1 nM and 5-10 nM, respectively. The somatotropin refractoriness of the SPI 2.3 gene appears to be due to the presence of distal (-2300 to -200) inhibitory element(s) in the promoter. Glucocorticoids exert both positive and negative effects on SPI promoter activity. Their stimulatory action appears to involve sequences located between positions -114 and -82, together with a more distal half glucocorticoid-responsive element, whereas their inhibitory effect is more likely mediated by sequences located between positions -41 and +8. In vitro transcription assays, performed with promoter-deletion mutants and competitor oligonucleotides, revealed the presence of a major functional C/EBP site located immediately upstream from the transcription-start point. Unfortunately, the regulatory features of SPI gene expression observed in intact cells were completely obliterated by breaking down the cell structure, and could not therefore be studied using cell-free systems.

Inhibition of rat tissue kallikrein gene family members by rat kallikrein-binding protein and alpha 1-proteinase inhibitor

The regulation of tissue kallikrein activity by plasma serine proteinase inhibitors (serpins) was investigated by measuring the association rate constants of six tissue-kallikrein family members isolated from the rat submandibular gland, with rat kallikrein-binding protein (rKBP) and alpha 1-proteinase inhibitor (alpha 1-PI). Both these serpins inhibited kallikreins rK2, rK7, rK8, rK9 and rK10 with association rate constants in the 10(3)-10(4) M-1.s-1 range, whereas only 'true' tissue kallikrein rK1 was not susceptible to alpha 1-PI. This results in slow inhibition of rK1 by plasma serpins, which could explain why this kallikrein is the only member of the gene family identified so far that induces a transient decrease in blood pressure when injected in minute amounts into the circulation.

Electroporation-mediated gene transfer into hepatocytes: preservation of a growth hormone response

An electroporation procedure is described which allows the introduction of foreign genes into freshly isolated rat hepatocytes while preserving their growth hormone responsiveness. A single-pulse procedure performed at low voltage (150-200 V) but with high capacitance (960 microF), conditions which caused minimal cell damage and increased hepatocyte survival in culture (greater than 80%), was found to be optimal for both the basal and the hormone-stimulated expression of transfected genes. Transfection of the cells suspended in a phosphate buffer at high concentrations (20-25 x 10(6)/ml) with large amounts of plasmid (30 micrograms/assay) gave the best results. Raising the temperature up to 25 or 37 degrees C (instead of 4 degrees C) decreased about twofold basal CAT expression but appeared to increase the magnitude (i.e., fold induction) of hormonal effects. Expression of the reporter gene driven by either a viral or a liver gene promoter reached a maximum after 24 h, a situation especially favorable when studying liver-specific gene expression known to decay rapidly in cultured hepatocytes. This procedure was successfully applied to the study of a growth hormone-dependent serine protease inhibitor gene promoter.

Discoordinate hormonal and ontogenetic regulation of four rat serpin genes

To understand the roles of four highly homologous rat hepatic serine protease inhibitor genes (Spi 2.1, Spi 2.2, Spi 2.3, and alpha 1-antitrypsin), we measured the hepatic content of their specific mRNAs under several physiological conditions. Spi 2.1 and 2.3 mRNAs, which are regulated by growth hormone, paralleled serum growth hormone levels developmentally. Only Spi 2.1 mRNA decreased with starvation, while Spi 2.2, 2.3, and alpha 1-antitrypsin mRNAs did not change. Despite the close homology of the Spi genes to mouse contrapsin, which is regulated by testosterone, none of the serine protease inhibitor mRNAs examined here was dependent on androgens for expression. Spi 2.2 mRNA displayed a unique ontogenetic regulation, with a rise in hepatic content at day 19 to levels five times that of any other age group. These studies confirm the importance of growth hormone in the regulation of Spi 2.1 and 2.3 mRNAs and suggest that Spi 2.2 mRNA may be regulated by metabolic alterations occurring in the weaning period.

Functional characterization of the promoter of pp63, a gene encoding a natural inhibitor of the insulin receptor tyrosine kinase

PP63 is a liver specific phosphorylated glycoprotein encoded by a single copy gene, which has the property of inhibiting both autophosphorylation and tyrosine kinase activity of the insulin receptor. In this study, we have analyzed the structure activity relationship of the pp63 gene promoter. Five protein binding sites were found in the proximal 5' flanking region of the gene (-223 to +4). Using oligonucleotides as competitors and purified recombinant C/EBP in footprinting and gel retardation assays, we identified two typical C/EBP sites (X1 and X3) plus a heterogenous, C/EBP-NF1 like site (X5), separated by two classical NF1 binding sites (X2 and X4). C/EBP or the related proteins were predominantly involved in supporting cell-free transcription. Occupancy of the first high affinity C/EBP site conferred almost maximal promoter efficiency, in vitro. However, this pp63 promoter activity remained very low as compared to that in intact hepatocytes. In these cells, occupancy of the first C/EBP (X1) and NF1 (X2) sites was already required for achieving a weak transcriptional activity. The use of the second C/EBP site (X3) strongly enhanced transcription, up to 60-70% of the maximum, whereas occupancy of the two more distal sites (X4 and X5) was necessary to fully activate the promoter. Thus, the strength of the promoter as well as the liver specific expression of pp63 gene appear to result from the interplay of several DNA-protein complexes involving mainly C/EBP and/or related proteins as well as the ubiquitous NF1 factor(s), rather than from the interaction of a more liver specific trans-acting factor with the promoter.

Analysis of proteins binding to the proximal promoter region of two rat serine protease inhibitor genes

The three serine protease inhibitor (SPI) rat genes expressed preferentially in liver share considerable structural features and, nonetheless, are transcriptionally regulated in completely different manners, more particularly after hypophysectomy or upon acute inflammation. DNase I footprinting and gel mobility shift analyses of the SPI 2.1 and 2.3 proximal promoter regions reveal the presence of three common protein binding sites (1 to 3, 3' to 5') located immediately upstream from the transcription start site. C/EBP, the liver-enriched factor, specifically interacts with site 1 whereas its related proteins (e.g.; DBP, LAP/NFIL6) most likely recognize sites 2 and 3. Another ubiquitous unidentified factor also binds to site 2. A liver-specific protein dependent on growth hormone, whose binding is competed out by an oligonucleotide reproducing an HNF3 motif, interacts exclusively with site 3. The 42 bp sequence which is found only within the SPI 2.3 promoter interacts with two ubiquitous factors, one of which is related to NF kappa B. Acute inflammation does not significantly affect the protein binding patterns observed with the SPI 2.1 or 2.3 proximal promoter sequences. Our results show an apparent discrepancy between the large magnitude of in vivo changes in SPI gene transcription mediated by hormones and the small alterations detected in vitro, in the DNA-protein interactions on the promoters.

Patchwork-structure serpins from silkworm (Bombyx mori) larval hemolymph

A new serpin (serine proteinase inhibitor), having antichymotryptic activity, was isolated from silkworm, Bombyx mori, larval hemolymph and was named silkworm antichymotrypsin II (sw-AchyII). Amino-acid-sequence analysis of sw-AchyII revealed that it consisted of 375 amino acids without cysteine or glycosylated residues. sw-AchyII formed an SDS-undissociable complex with alpha-chymotrypsin, but this complex was broken down at pH 12.5 into alpha-chymotrypsin and sw-AchyII in which the reactive site was cleaved. Amino-acid-sequence analysis after cleavage identified in P1-P1' residue at the reactive site of sw-AchyII as Phe340-Met341. The amino acid sequence from the amino terminus to residue 336 was completely identical to the corresponding region of sw-AT [Takagi, H., Narumi, H., Nakamura, K. & Sasaki, T. (1990) J. Biochem. (Tokyo) 108, 372-378]. The degree of similarity between sw-AchyII and silkworm antitrypsin (sw-AT) from residue 337 to the carboxy terminus was only 46%. Reactive sites of both serpins were in the variable regions.

Isolation of two cDNAs encoding novel alpha 1-antichymotrypsin-like proteins in a murine chondrocytic cell line

We have isolated two novel serpin-encoding sequences from EB22, a chondrocytic cell line derived from a mouse teratocarcinoma. Both sequences fall within the Spi-2 sub-family, and are related to the gene encoding human alpha 1-antichymotrypsin (ACT), a major acute-phase reactant. Considerable amplification of the Spi-2 gene family in the mouse has occurred, hindering the identification of a functional equivalent of the human gene. However, one of the sequences described here, EB22/4, exhibits several features which indicate that it may represent the physiological rodent equivalent of ACT. The sequence is expressed in the liver, as expected, and is induced several-fold during the acute-phase response. The P1 amino acid residue, which is primarily responsible for inhibitor specificity, is Met rather than the human Leu, most probably a functionally conservative substitution. Analysis of the orthologous sequence in related rodents demonstrates conservation of the predicted reactive centre-encoded specificity. The second isolated cDNA, EB22/3, encodes an unexpected Cys residue at the P1 position in the reactive centre, and represents a novel sub-class of the Spi-2 serine proteinase inhibitor (serpin)-encoding gene family. At least one of the sequences appears to be expressed at sites of skeletal deposition during the later stages of mouse foetal development, indicating a role for serpins during development.

Developmental regulation of the hepatic acute phase response

For evaluation of the ontogenetic regulation of the acute phase response, inflammation was induced in Fischer rat litters at different postnatal ages. Four homologous rat hepatic serine protease inhibitor (Spi 2.1, Spi 2.2, Spi 2.3, and alpha 1-antitrypsin) mRNAs were measured in livers 24 h after injection. Animals mounted both positive and negative acute phase responses at all ages, but responses were blunted in young animals, reaching adult levels by days 7-19. alpha 1-Antitrypsin mRNA had no response, and Spi 2.2 mRNA had 50% the rise seen in adults on days 3 and 7. Spi 2.1 and 2.3 mRNAs, negative acute phase reactants, showed attenuation of adult response to inflammation in infant animals of 33% (Spi 2.1) and 40% (Spi 2.3). In hypophysectomized animals, the responses of Spi 2.2, 2.3, and alpha 1-antitrypsin mRNAs after turpentine stimulation were similar to that of normal animals, whereas Spi 2.1 mRNA did not change. In conclusion, infant animals mount a blunted response to tissue injury; multiple factors may be involved in the development of the full adult response. Immaturity of the pituitary may play a role in the suppression of Spi 2.1 mRNA's response during inflammation in infant animals. These highly evolutionary related genes will be helpful in identifying specific factors regulating gene expression in inflammation and development.

Primary structure and assignment to chromosome 6 of three related rat genes encoding liver serine protease inhibitors

Three closely related SPI genes which encode highly homologous proteins of the serine protease inhibitor family secreted by rat liver (SPI-1, SPI-2 and SPI-3), were isolated from genomic libraries and sequenced, totally (SPI-2) or partially (SPI-1 and SPI-3). These genes all map on rat chromosome 6. Each of them spans about 10 kb and contains five exons separated by four introns, located at equivalent positions. S1 mapping analysis indicated that initiation of transcription occurs at the same position (tsp) in each of the three genes. In vitro transcription experiments demonstrated the presence of promoter elements upstream from the putative tsp. Detailed analysis of 5'-flanking sequences in the three SPI revealed major differences. A high degree of identity (70%) was found within a 350-bp region preceding the 'cap' site, with the exception of a 42-bp spacer, which was only found in SPI-3. Upstream from that point, SPI-1 and SPI-2 sequences remain largely homologous over at least 1 kb but completely diverge from the corresponding sequence in SPI-3. This may, at least partly, account for the differential regulation of the three SPI observed during acute inflammation and upon hypophysectomy.