Improved hybridization assays employing tailed oligonucleotide probes: a direct comparison with 5'-end-labeled oligonucleotide probes and nick-translated plasmid probes

Monomorphic HLA class I-(non-A, non-B) expression on Ewing's tumor cell lines, modulation by TNF-alpha and IFN-gamma

In this study, the expression of polymorphic and non-polymorphic MHC antigens in Ewing's tumor (ET) cells was examined by surface staining, Western blots and transcriptional analysis. Cell lines derived from Ewing's tumors largely lack polymorphic HLA class Ia antigens of both the HLA-A and the HLA-B loci but binding of monomorphic HLA antibodies indicates significant expression of HLA-C locus antigens and/or HLA class Ib molecules. HLA Ib molecules encoded by the HLA-E, -F or -G loci with a molecular mass of less than 44 kDa were not detected in lysates of either constitutive or TNF-alpha plus IFN-gamma treated ET cells. Two representative ET cell lines with either detectable HLA-A, -B antigens (A673) or absolutely non-detectable HLA-A, -B antigens (SK-ES-1) were further subjected to transcriptional analysis. A673 mRNA hybridized with HLA-A, -B, -C and HLA-E-specific probes in Northern blots. By contrast, mRNA specific for HLA-A, -B, -C was negative in SK-ES-1 but TNF-alpha plus IFN-gamma reconstituted HLA-A, -B, -C transcription in this cell line. HLA-E was transcribed in A673 but not in SK-ES-1. Combining mRNA and surface expression of HLA class Ia molecules results in a highly variable pattern of defective HLA class I expression in this type of neuroectodermal tumor. The involvement of the ET-specific fusion transcript EWS/Fli-1 in modulating the HLA-A and -B locus antigens is likely to occur by the upregulation of c-myc in these tumors. The exceptionally constant expression of HLA-C or some other non-A, non-B antigens (reactive with defined monoclonal antibodies) implies important consequences on tumor-cell resistance against specific CTL and NK activity in vivo.

Aberrant expression of MUC5AC and MUC6 gastric mucin genes in colorectal polyps

Altered mucin glycosylation and the de novo appearance of gastric mucin antigens have been described in colonic adenomas. The purpose of our study was to determine if expression of the gastric mucin genes MUC5AC and MUC6 occurs in colorectal adenomas and whether this correlates with histopathologic criteria of malignant potential. Immunohistochemical staining using antibodies against MUC5AC and MUC6 tandem repeat synthetic peptides was performed on specimens of normal colon mucosa (n = 26), hyperplastic polyps (n = 9) and adenomatous polyps (n = 111). Mucin mRNA levels were determined using RNase protection assays using riboprobes corresponding to unique non-repetitive sequences. MUC5AC and MUC6 staining were rarely detected and of low intensity in normal colon and hyperplastic polyps. The number of immunoreactive polyps and intensity of MUC5AC and MUC6 staining were greatest in larger adenomas of moderate villous histology and dysplasia. MUC5AC and MUC6 staining tended to decrease in highly villous polyps with severe dysplasia. Increased MUC5AC mRNA levels were found in 26/45 of adenomas tested compared with 0/9 normal colon specimens. MUC6 mRNA levels were found in 20/45 of adenomas compared with 1/9 normal colon specimens. MUC5AC and MUC6 mRNA were present more frequently and at higher levels in polyps with intermediate stages of size, villous histology and dysplasia. We conclude that aberrant expression of MUC5AC and MUC6 mucin genes is likely responsible for an expanded repertoire of mucin antigen expression in colorectal neoplasia.

NGF-induction of the expression of ChAT mRNA in PC12 cells and primary cultures of embryonic rat basal forebrain

The objective of this study was to examine the role of nerve growth factor (NGF) in regulation of expression of the cholinergic phenotype. NGF was administered to PC12 cells or primary cultures of embryonic (E17) rat basal forebrain for 2 days, then steady-state levels of choline acetyltransferase (ChAT) mRNA was monitored. Expression of ChAT mRNA isoforms was investigated using reverse transcription-polymerase chain reaction (RT-PCR) to amplify different upstream regions of the ChAT transcripts, and Southern blot analysis was used to verify identity of the PCR products. An NGF-induced increase of 1.8- and 1.5-fold in steady-state level of the ChAT transcript containing the M-exon (M-ChAT) was observed in PC12 cells and embryonic rat basal forebrain neurons, respectively. Also, a 2-fold increase in ChAT protein as determined by western blot analysis was associated with an NGF-mediated increase of 1.7-fold in ChAT activity in rat basal forebrain neurons within the same cultures following 4 days of NGF treatment.

Regulation of rat hepatic cytochrome P450 expression by sterol biosynthesis inhibition: inhibitors of squalene synthase are potent inducers of CYP2B expression in primary cultured rat hepatocytes and rat liver

The effects of treatment with squalestatin 1, a potent inhibitor of squalene synthase, the first committed enzyme of sterol biosynthesis, were examined on cytochrome P450 expression in primary cultured rat hepatocytes and rat liver. Incubation of cultured hepatocytes with squalestatin 1 caused marked accumulations (maximal elevations that were approximately 25-100% of phenobarbital-elicited increases) of CYP2B mRNA and immunoreactive protein but not of CYP1A, CYP3A, or CYP4A. Squalestatin 1 treatment increased CYP2B and 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA content in hepatocyte cultures with comparable potencies (ED50 = 5.0 and 18 nM, respectively), and significantly induced CYP2B (mRNA, immunoreactive protein, and pentoxyresorufin O-dealkylase activity) in the livers of treated rats, producing maximal increases at a dose of 25 mg/kg/day that were approximately 32-87% of phenobarbital-induced increases. Squalestatin 1 treatment induced both CYP2B1 and CYP2B2 and activated reporter gene expression in cultured hepatocytes transiently transfected with a plasmid containing approximately 2.4 kb of CYP2B1 gene 5'-flanking region or containing a previously described phenobarbital-responsive region. Coincubation of cultured hepatocytes with 25-hydroxycholesterol suppressed squalestatin 1-mediated CYP2B and 3-hydroxy-3-methylglutaryl coenzyme A mRNA induction with approximately the same potency. Treatment of cultures with SQ-34919, a structurally distinct squalene synthase inhibitor, produced the same selective CYP2B mRNA induction as did squalestatin 1. These results suggest that inhibition of hepatic sterol synthesis activates processes that culminate in increased CYP2B gene transcription.

In situ hybridization analysis of immunoglobulin heavy chain variable gene expression with family specific oligonucleotide probes

We have developed an improved in situ hybridization (ISH) technique for the analysis of human immunoglobulin heavy chain variable (V(H)) gene family expression in suspensions of human B lymphocytes. Oligonucleotide probes specific for framework region (FR) consensus germline sequences for each of the seven human V(H) gene families were designed and hybridization conditions were developed to accommodate the greatest degree of V(H) gene variation, maximize the sensitivity of transcript detection, and assure the specificity of the technique. The hybridization parameters were rigorously characterized by Southern hybridization to a panel of 30 V(H) cDNA clones and by ISH to 17 B cell lines expressing characterized V(H) genes. Results obtained with ISH using V(H) gene family and isotype-specific gene probes correlated well with histochemical measures of Ig gene product expression. Profiles of cellular V(H) gene expression were generated for mitogen stimulated peripheral blood B lymphocytes from six normal subjects. When compared with estimates of frequency of V(H) genes in the human germline, the results were consistent with a random pattern of V(H) family utilization.

A bacterial group II intron encoding reverse transcriptase, maturase, and DNA endonuclease activities: biochemical demonstration of maturase activity and insertion of new genetic information within the intron

The Lactococcus lactis group II intron Ll.ltrB is similar to mobile yeast mtDNA group II introns, which encode reverse transcriptase, RNA maturase, and DNA endonuclease activities for site-specific DNA insertion. Here, we show that the Lactococcal intron can be expressed and spliced efficiently in Escherichia coli. The intron-encoded protein LtrA has reverse transcriptase and RNA maturase activities, with the latter activity shown both in vivo and in vitro, a first for any group II intron-encoded protein. As for the yeast mtDNA introns, the DNA endonuclease activity of the Lactococcal intron is associated with RNP particles containing both the intron-encoded protein and the excised intron RNA. Also, the intron RNA cleaves the sense-strand of the recipient DNA by a reverse splicing reaction, whereas the intron-encoded protein cleaves the antisense strand. The Lactococcal intron endonuclease can be obtained in large quantities by coexpression of the LtrA protein with the intron RNA in E. coli or reconstituted in vitro by incubating the expressed LtrA protein with in vitro-synthesized intron RNA. Furthermore, the specificity of the endonuclease and reverse splicing reactions can be changed predictably by modifying the RNA component. Expression in E. coli facilitates the use of group II introns for the targeting of specific foreign sequences to a desired site in DNA.

Expression of the epidermal growth factor receptor gene in human intestinal metaplasia: a preliminary report

BACKGROUND

The role of growth factors/receptors in the etiopathology and/or development of gastric cancer has recently come under scrutiny, since overexpression or amplification of the EGF system has been found in many intestinal type gastric cancers and related to a more aggressive behavior. Since these gastric carcinomas appear to develop from intestinal metaplasia, a study was planned to investigate whether overexpression of the EGF-receptor gene also occurred in intestinal metaplastic mucosa.

METHODS

Patients underwent upper GL endoscopy. Gastric biopsies for routine histology, Helicobacter pylori detection, quantification of intestinal metaplasia and EGF-R expression analysis were performed. A 30mer EGF-R specific oligonucleotide was end-labeled and used to probe a dot blot filter containing the RNA from the bioptic samples.

RESULTS

Though all the gastric samples transcribed the EGF-R gene to a detectable level, overexpression of the EGF-R gene was found in the metaplastic mucosa in a minority of patients.

CONCLUSIONS

These preliminary findings suggest that overexpression of the EGF-R gene is infrequent in the metaplastic gastric mucosa.

Expression of fast myosin heavy chain transcripts in developing and dystrophic chicken skeletal muscle

The expression of fast myosin heavy chain (MyHC) genes was examined in vivo during fast skeletal muscle development in the inbred White Leghorn chicken (line 03) and in adult muscles from the genetically related dystrophic White Leghorn chicken (line 433). RNA dotblot and northern hybridization was employed to monitor MyHC transcript levels utilizing specific oligonucleotide probes. The developmental pattern of MyHC gene expression in the pectoralis major (PM) and the gastrocnemius muscles was similar during embryonic development with three embryonic MyHC isoform genes, Cemb1, Cemb2, and Cemb3, sequentially expressed. Following hatching, MyHC expression patterns in each muscle differed. The expression of MyHC genes was also studied in muscle cell cultures derived from 12-day embryonic pectoralis muscles. In vitro, Cvent, Cemb1, and Cemb2 MyHC genes were expressed; however, little if any Cemb3 MyHC gene expression could be detected, even though Cemb3 was the predominant MyHC gene expressed during late embryonic development in vivo. In most adult muscles other than the PM and anterior latissimus dorsi (ALD), the Cemb3 MyHC gene was the major adult MyHC isoform. In addition, two general patterns of expression were identified in fast muscle. The fast muscles of the leg expressed neonatal (Cneo) and Cemb3 MyHC genes, while other fast muscles expressed adult (Cadult) and Cemb3 MyHC genes. MyHC gene expression in adult dystrophic muscles was found to reflect the expression patterns found in corresponding normal muscles during the neonatal or early post-hatch developmental period, providing additional evidence that avian muscular dystrophy inhibits muscle maturation.

Selective inhibition of interleukin-1 beta gene expression in activated RAW 264.7 macrophages by interferon-gamma

The ability of interleukin-1 (IL-1) to activate epidermal cell populations supports its role as a key cytokine in the pathogenesis of a number of inflammatory skin diseases. In the present study, we have examined the effect of interferon (IFN)-gamma on the expression of the IL-1 beta gene in mouse RAW 264.7 macrophages activated by lipopolysaccharide (LPS) plus tumor necrosis factor (TNF)-alpha. Incubation of macrophages with both LPS and TNF-alpha resulted in the expression of both IL-1 beta and inducible nitric oxide synthase (iNOS) mRNA transcripts and increased the release of IL-1 beta protein and nitrite production in culture supernatants. Addition of IFN-gamma up-regulated the expression of the iNOS gene in cells activated by LPS + TNF-alpha, but significantly suppressed the induction of IL-1 beta gene expression in a dose-dependent manner. The suppression required neither de novo protein synthesis nor involved destabilization of the mRNA transcripts. Together, these findings suggest that IFN-gamma can be an important regulatory cytokine in a chronic inflammatory site and may explain its purported anti-inflammatory effects in certain dermatological diseases.

Enzymatic labeling of nucleic acids

Enzymatic labeling of nucleic acids is a fundamental tool in molecular biology with virtually every aspect of nucleic acid hybridization technique involving the use of labeled probes. Different methods for enzymatic labeling of DNA, RNA and oligonucleotide probes are available today. In this review, we will describe both radioactive and nonradioactive labeling methods, yet the choice of system for labeling the probe depends on the application under study.

PDGF-B producing cells and PDGF-B gene expression in normal gingival and cyclosporine A-induced gingival overgrowth

It has been proposed that healthy gingiva is in a continuous state of wound repair. Thus, one might expect to find cells in normal gingiva producing growth factors associated with wound healing such as platelet-derived growth factor B chain (PDGF-B). One might also expect to find increased numbers of these cells or increased amounts of these growth factors in conditions which involve increased tissue volume such as drug-induced gingival overgrowth (DGO). The purpose of this study was to quantify PDGF-B gene expression and identify cells producing PDGF-B in normal gingiva and DGO. Cyclosporine A (CSA) was selected as a prototype of the overgrowth condition. Twelve patients with clinical CSA DGO and 12 patients with no DGO or history of drugs known to cause DGO were selected for study. Frozen sections of gingival specimens from these patients were subjected to in situ hybridization for PDGF-B mRNA. Positive cells were counted and expressed as mean +/- SEM cells/mm2 of lamina propria. Morphometric analysis revealed 6.2 +/- 1.9 cells/mm2 for control gingiva and 10.3 +/- 3.4 cells/mm2 for CSA DGO samples. There was no statistically significant difference between groups. PDGF-B gene expression was measured in these cells and expressed as mean +/- SEM silver grains/cells. There was a significant upregulation of PDGF-B gene expression in cells from the CSA DGO group (39.5 +/- 14.7 silver grains/cell for normal gingiva vs. 255.3 +/- 77.1 silver grains/cell for CSA DGO samples; P < 0.001). The presence of PDGF-B in these cells was confirmed in all cases by immunocytochemical localization. Additionally, PDGF-B producing cells were identified as macrophages in sections taken from an additional patient with CSA DGO by double immunofluorescence labeling of the CD51 membrane marker for macrophages and intracellular PDGF-B. These findings are consistent with the concept that healthy gingiva is in a continuous state of wound repair and support the hypothesis that CSA DGO is associated with enhanced macrophage PDGF-B gene expression rather than an increase in the number of PDGF-B producing macrophages.

Molecular cloning of a developmentally regulated protein isolated from excretory-secretory products of larval Dirofilaria immitis

Three proteins isolated from the excretory-secretory products (ES) of larval Dirofilaria immitis have been previously characterized and termed the 20, 22L and 22U kDa proteins. Two of the proteins (20 and 22L) were produced and released around the time of the third molt and were specifically recognized by immune dog sera. An amino acid sequence common to both proteins was used to synthesize a DNA probe to molecularly clone these molecules from a 48-h third stage larval cDNA library. The DNA sequence of the isolated clones encoded a 17.5 kDa protein with a 21 amino acid hydrophobic leader sequence that when removed yielded a 15.3 kDa protein starting with the N-terminal sequence obtained from the 20 kDa protein and containing all sequences obtained from tryptic peptides of the 20 and 22L kDa proteins. It was hypothesized that the 20 and 22L kDa proteins were the same, differing only by a 21 amino acid hydrophobic leader sequence which was later cleaved. The calculated molecular masses were consistent with those determined by reducing Tris-tricine SDS-PAGE. Expression of the protein without the leader sequence was accomplished in Escherichia coli. Antiserum raised against the expressed protein demonstrated the presence of the protein in L3 and L4, but not in adults or microfilariae. Expression of the protein with the leader sequence using a baculovirus system demonstrated processing of the signal sequence at the same time as found in larval D. immitis ES. Sera from dogs immune to infection were reactive with the D. immitis proteins expressed in either E. coli or insect cells.

Characterization of toxin-producing cyanobacteria by using an oligonucleotide probe containing a tandemly repeated heptamer

Cyanobacteria produce toxins that kill animals. The two main classes of cyanobacterial toxins are cyclic peptides that cause liver damage and alkaloids that block nerve transmission. Many toxin-producing strains from Finnish lakes were brought into axenic culture, and their toxins were characterized. Restriction fragment length polymorphism analysis, probing with a short tandemly repeated DNA sequence found at many locations in the chromosome of Anabaena sp. strain PCC 7120, distinguishes hepatotoxic Anabaena isolates from neurotoxin-producing strains and from Nostoc spp.

Transthyretin and cystatin C are catabolized in proximal tubular epithelial cells and the proteins are not useful as markers for renal cell carcinomas

Ten human kidney specimens and thirty-two renal cell carcinomas were investigated for the presence of transthyretin mRNA and cystatin C mRNA using Northern blot analysis. Five of ten kidney specimens and 15 of 32 renal carcinomas were also immunohistochemically investigated for the presence of the corresponding proteins. Transthyretin mRNA could not be detected in any of the normal or neoplastic tissue preparations, whereas low amounts of cystatin C mRNA were found in nine of ten normal kidneys and in 24 of 32 renal cell carcinomas. Immunoreactive transthyretin and cystatin C were present in proximal tubular epithelial cells of all kidney specimens, whereas neither of the proteins was detected the tumour cells of the renal carcinomas. Immunoreactive cystatin C was, however, demonstrated in scattered monocyte/macrophage-like cells. We conclude that the presence of immunoreactive transthyretin and cystatin C in proximal tubular cells of the kidney is most likely due to reabsorption of the proteins from the primary urine. The small amounts of cystatin C mRNA in some of the normal and neoplastic renal preparations are probably due to cystatin C synthesis in macrophages. Transthyretin has been recommended as an immunohistochemical marker for renal cell carcinomas. Our results, however, clearly indicate that neither transthyretin nor cystatin C constitutes a useful marker for such neoplasms.

Infection of central nervous system cells by ecotropic murine leukemia virus in C58 and AKR mice and in in utero-infected CE/J mice predisposes mice to paralytic infection by lactate dehydrogenase-elevating virus

Certain mouse strains, such as AKR and C58, which possess N-tropic, ecotropic murine leukemia virus (MuLV) proviruses and are homozygous at the Fv-1n locus are specifically susceptible to paralytic infection (age-dependent poliomyelitis [ADPM]) by lactate dehydrogenase-elevating virus (LDV). Our results provide an explanation for this genetic linkage and directly prove that ecotropic MuLV infection of spinal cord cells is responsible for rendering anterior horn neurons susceptible to cytocidal LDV infection, which is the cause of the paralytic disease. Northern (RNA) blot hybridization of total tissue RNA and in situ hybridization of tissue sections demonstrated that only mice harboring central nervous system (CNS) cells that expressed ecotropic MuLV were susceptible to ADPM. Our evidence indicates that the ecotropic MuLV RNA is transcribed in CNS cells from ecotropic MuLV proviruses that have been acquired by infection with exogenous ecotropic MuLV, probably during embryogenesis, the time when germ line proviruses in AKR and C58 mice first become activated. In young mice, MuLV RNA-containing cells were found exclusively in white-matter tracts and therefore were glial cells. An increase in the ADPM susceptibility of the mice with advancing age correlated with the presence of an increased number of ecotropic MuLV RNA-containing cells in the spinal cords which, in turn, correlated with an increase in the number of unmethylated proviruses in the DNA extracted from spinal cords. Studies with AKXD recombinant inbred strains showed that possession of a single replication-competent ecotropic MuLV provirus (emv-11) by Fv-1n/n mice was sufficient to result in ecotropic MuLV infection of CNS cells and ADPM susceptibility. In contrast, no ecotropic MuLV RNA-positive cells were present in the CNSs of mice carrying defective ecotropic MuLV proviruses (emv-3 or emv-13) or in which ecotropic MuLV replication was blocked by the Fv-1n/b or Fv-1b/b phenotype. Such mice were resistant to paralytic LDV infection. In utero infection of CE/J mice, which are devoid of any endogenous ecotropic MuLVs, with the infectious clone of emv-11 (AKR-623) resulted in the infection of CNS cells, and the mice became ADPM susceptible, whereas littermates that had not become infected with ecotropic MuLV remained ADPM resistant.

The alternative splicing of human Fc gamma RII mRNA is regulated by activation of B cells with mIgM cross-linking, interleukin-4, or phorbolester

The human type two IgG binding receptors (Fc gamma RII) are encoded by three genes (Fc gamma RIIA, -B and C) resulting in at least six protein isoforms generated by alternative mRNA splicing. Surface expression of Fc gamma RII has been shown to be modulated during B cell activation, although data characterizing the isoform(s) expressed are not available. The extracellular as well as the transmembrane domains of various Fc gamma RII are highly homologous. Only the intracellular domains vary between the different Fc gamma RII isoforms, suggesting differences in signal transduction. Using reverse transcriptase and polymerase chain reaction of mRNA obtained from resting tonsil B cells, we show that the majority of Fc gamma RII mRNA species to be of b2 type, although b1 type and a low level of Fc gamma RIIa type are also present. Culturing the cells for 18 h in the presence of 2.5 U/ml interleukin-4 or 10 micrograms/ml affinity-purified anti-IgM F(ab')2 fragments induced a switch in alternative splicing, resulting in a significant increase of Fc gamma RIIb1 mRNA expression, while the synthesis of Fc gamma RIIb2 mRNA was down-regulated. Stimulation of B cells with 100 ng/ml phorbol 12-myristate 13-acetate induced similar alteration, although only after 48-h treatment. The accumulation of Fc gamma RIIb1 and the reduction of both Fc gamma RIIb2 and Fc gamma RIIa mRNA in activated cells is accompanied by the enhanced expression of Fc gamma RII on the cell surface, representing most probably the Fc gamma RIIb1 isoform. Heat-aggregated IgG inhibited the anti-IgM-induced proliferation of resting but not that of activated B cells, suggesting that aggregation of Fc gamma RIIb2 constitutively expressed on resting B cells might be responsible for the prevention of inadequate activation of resting B cells.

Cyclosporine A upregulates interleukin-6 gene expression in human gingiva: possible mechanism for gingival overgrowth

Cyclosporine A (CsA) is a widely used immunosuppressant for transplant patients and is also used for the treatment of a wide variety of systemic diseases with immunologic components. A prominent side effect of CsA administration is gingival overgrowth. It has been postulated that CsA alters fibroblast activity through effects on various cytokines such as the interleukins, however, as yet, data concerning the molecular mechanisms involved in connective tissue proliferation are still preliminary in nature. The purpose of this study was to evaluate interleukin-6 (IL-6) gene expression in gingival tissues of patients receiving CsA therapy and exhibiting gingival overgrowth. Radioimmunoassay (RIA) demonstrated a significant difference in tissue levels of IL-6 as mean +/- SEM. IL-6 content in CsA-stimulated tissue was 184.3 +/- 30.2 ng/mg total protein versus 23.3 +/- 6.5 ng/mg total protein in control tissue. In situ hybridization indicated that overgrown gingival tissues from patients taking CsA had a significantly higher content of IL-6 mRNA when compared to control tissues. Expressing IL-6 mRNA levels as silver grains/cell, CsA-stimulated tissue had 166.9 +/- 12.0 grains of IL-6 mRNA/cell while control tissue had 12.8 +/- 3.0 grains of IL-6 mRNA/cell. These results demonstrate that CsA therapy results in increased levels of IL-6 protein and IL-6 mRNA in overgrown human gingival tissues. This is the first report of CsA-upregulated IL-6 gene expression in vivo, and may explain in part the molecular mechanisms responsible for CsA-induced gingival overgrowth.

Activation of a vmp pseudogene in Borrelia hermsii: an alternate mechanism of antigenic variation during relapsing fever

The relapsing fever agent, Borrelia hermsii, undergoes multiphasic antigenic variation to evade its host's immune response. A frequently observed switch is serotype 7 to 26. Unlike silent vmp genes previously characterized, the transcriptionally silent vmp26 sequence was a pseudogene in lacking a start codon. In serotype 7 the location of the silent vmp26 sequence just downstream of vmp7 on the expression plasmid, as well as on the silent plasmid, was also unique. The demonstration of a predicted circular recombination product in serotype 7 but not serotype 21 populations indicates that the pseudogene was activated by an intramolecular recombination producing a deletion of DNA between 20-nucleotide direct repeats in vmp7 and psi vmp26.

Anomalous binding of radiolabeled oligonucleotide probes to plaques and tangles in Alzheimer disease hippocampus

Several reports indicate that Alzheimer disease (AD) brain contains elevated levels of heat shock 70 proteins. To determine the cellular localization of the heat shock 70 mRNAs, specific oligonucleotide probes were in situ hybridized to AD and control brains. When oligonucleotides were in situ hybridized to brain sections with no AD neuropathology, hybridization was cell-specific and prior ribonuclease (RNase) treatment of adjacent sections resulted in no hybridization signal. However, in situ hybridization to AD hippocampus resulted in heavy grain deposition over senile plaques and neurofibrillary tangles. Despite altering a number of experimental variables, we observed a similar pattern of grain deposition with most of the oligonucleotides tested, including one oligonucleotide specific for glutamic acid decarboxylase mRNA. In situ hybridization with either an RNA probe for glutamic acid decarboxylase or an oligonucleotide probe specific for 18S rRNA did not show this pattern of grain deposition. In control studies a sense hsc70 oligonucleotide showed no grain deposition in either cerebellum or hippocampus. Sections from AD hippocampus pretreated with RNase prior to in situ hybridization demonstrated enhanced grain deposition with the majority of probes tested. Anomalous in situ hybridization to AD hippocampus was usually eliminated by removing formamide from the posthybridization washes, although post-RNase sticking often remained intense. These findings indicate that artifactual probe binding to senile plaques and neurofibrillary tangles may complicate the analysis of in situ hybridization studies using oligonucleotide probes to determine mRNA distribution in AD brain.

Synthesis of platelet-derived growth factor by cells of splenic red pulp in normal rats

A population of cells in the spleens of normal rats was found to contain platelet-derived growth factor (PDGF) B chain mRNA. These cells were found predominantly in the red pulp and nuclear morphology of some was consistent with that of macrophages. Similar cells were also shown by immunocytochemical staining to contain PDGF-AB/BB. These PDGF-positive cells were also found almost exclusively in the red pulp. It has been suggested by others that PDGF plays an important role in the function of the lymphohemopoietic microenvironment.

Alternate splicing creates two forms of the human kit protein

The Kit gene encodes for a transmembrane tyrosine kinase receptor that is expressed during early hematopoiesis and in a large proportion of blast cells of patients with acute myeloblastic leukemia (AML). Tissue culture studies have revealed that the growth factor recognized by the Kit protein is a stimulator of both colony formation and self renewal of AML cells. During an analysis of the Kit gene in AML cells we identified two different RNA transcripts differing by 12 nucleotides just 5' of the transmembrane encoding region. Analysis of a variety of tissues revealed that both forms of RNA are expressed in all of the tissues that produce Kit. Sequencing of the corresponding genomic region revealed that the two forms of RNA arose through the alternate use of 5' splice donor sites.

HLA-G: expression in human keratinocytes in vitro and in human skin in vivo

Classical, polymorphic major histocompatibility complex class I molecules are expressed on most nucleated cells. They present peptides at the cell surface and, thus, enable the immune system to scan peptides for their antigenicity. The function of the other, nonclassical class I molecules in man is controversial. HLA-G which has been shown by transfection experiments to be expressed at the cell surface, is only transcribed in placental tissue and in the fetal eye. Therefore, a role of HLA-G in the control of rejection of the allogeneic fetus has been discussed. We found that HLA-G expression is induced in keratinocytes by culture in vitro. Three different alternative splicing products of HLA-G can be detected: a full length transcript, an mRNA lacking exon 3 and a transcript devoid of exon 3 and 4. Reverse transcription followed by polymerase chain reaction also revealed the presence of HLA-G mRNA in vivo in biopsies of either diseased or healthy skin.

Expression of serum amyloid A genes in mink during induction of inflammation and amyloidosis

Serum amyloid A (SAA) is an acute phase protein and the precursor of amyloid protein A (AA) in deposits of secondary amyloidosis. Several isotypes exist in mink, but previous studies suggest that mink AA is derived from only one. To assess the effect of repeated episodes of inflammation and induction of amyloidosis, qualitative and quantitative changes in hepatic and extrahepatic SAA mRNA were studied. Young female mink received subcutaneous lipopolysaccharide injections for amyloid induction. Studies were performed using RNA probes and oligonucleotide probes specific for each of two SAA mRNA species. Northern blot hybridization showed that hepatic SAA1 and SAA2 mRNA levels increased dramatically after inflammatory stimulation, and were subsequently maintained at elevated levels, showing considerable interindividual variation, but only a slight decrease during repeated inflammatory stimuli and the early stages of amyloid deposition. No preferential accumulation of mRNA specifying a particular isotype was found during the experiment. Differential expression of mink SAA mRNA during repeated inflammatory stimulation does not seem to explain why only SAA2-derived AA is found in amyloid deposits. Extrahepatic SAA mRNA seemed to be independently regulated and may thus represent another, yet not characterized, SAA isotype.

Alterations in actin-binding beta-thymosin expression accompany neuronal differentiation and migration in rat cerebellum

The beta 4- and beta 10-thymosins, recently identified as actin monomer-sequestering proteins, are developmentally regulated in brain. Using specific mRNA and protein probes, we have used in situ hybridization and immunohistochemical techniques to investigate the distribution of the beta-thymosin mRNAs and their proteins in developing rat cerebellum. Early in postnatal development, both beta-thymosin mRNAs were expressed at highest levels in the postmitotic, premigratory granule cells of the external granular layer; expression diminished as granule cells migrated to and differentiated within the developing internal granular layer. In addition, both beta-thymosin proteins were present in bundles of cerebellar afferent fibers in the white matter at this time. Throughout the maturation period, both proteins were present in elongating parallel fibers in the upper portion of the molecular layer. Later in cerebellar development, thymosin beta 4, but not thymosin beta 10, was expressed in Golgi epithelial cells and Bergmann processes. Thymosin beta 4 was expressed in a small population of cells with microglial morphology scattered throughout the gray and white matter. Thymosin beta 10 was detected in an even smaller population of glia. Expression of thymosin beta 4 and thymosin beta 10 in premigratory granule cells and in growing neuronal processes is consistent with the possibility that both beta-thymosins are involved in the dynamics of actin polymerization during migration and process extension of neurons.

Differential expression of rabbit serum amyloid A genes in response to various inflammatory agents

Serum amyloid A (SAA) is an acute-phase plasma protein which increases up to 1000-fold after an acute-phase stimulus. Several SAA genes and corresponding protein isotypes exist in individual species. Liver is the main source of production, but extra-hepatic SAA expression has been described. In this study inflammation was induced in rabbits with lipopolysaccharide, turpentine, or casein. Transcription of SAA mRNA was studied using Northern blot analysis with probes specific for three different rabbit SAA isotypes and analysed by scanning densitometry. In the stimulated liver slight variation in SAA mRNA transcription level was seen after stimulation with different inflammatory agents. After lipopolysaccharide-stimulation SAA gene expression was also seen in most of the extra-hepatic organs. After turpentine stimulation SAA mRNA was seen in the liver, the ovary, and the small intestines, and after casein stimulation only in the liver and the ovary. SAA1 and SAA2 were induced exclusively in the liver, while SAA3 was induced mainly in the extra-hepatic organs. This indicates that the SAA genes probably are independently regulated both in relation to stimulus, gene- and tissue-specificity.

Analysis in Neisseria meningitidis and other Neisseria species of genes homologous to the FKBP immunophilin family

The immunophilin family of FK506-binding proteins (FKBPs), involved in eukaryotic protein-folding and cell regulation, have recently been found to have prokaryotic homologues. Genes with sequences homologous to those encoding human FKBPs were examined in Neisseria species. An FKBP DNA sequence was present, as shown by the polymerase chain reaction and Southern blotting experiments, in the chromosome of Neisseria meningitidis (14 strains) and in all 11 different commensal Neisseria spp. studied, but was not found in Neisseria gonorrhoeae (11 strains tested) or in Moraxella catarrhalis. The nucleotide and predicted protein sequences of the FKBP-encoding domain from five of the meningococcal strains were highly conserved (e.g. > or = 97% homologous). The meningococcal nucleotide sequence was > or = 93% homologous and the consensus meningococcal protein sequence was > or = 97% homologous to FKBP sequences found in seven different commensal Neisseria spp. The meningococcal nucleotide and predicted protein sequences were > or = 59% homologous to the conserved C-terminus of the human FKBP gene family. The FKBP nucleotide sequence was present as a single copy in the chromosome of commensal Neisseria spp. and in most strains of N. meningitidis. The FKBP gene was linked to the silent pilin locus, pilS, in class II-piliated meningococcal strains. In meningococcal strains expressing class I pili, the FKBP gene was linked to one of several pilS loci but not the pilE locus present in these strains. FKBP genes found in commensal Neisseria spp. were not linked to known pilin loci.

Reduction in striatal D2 dopamine receptor mRNA and binding following AF64A lesions

Unilateral lesions by a cholinotoxin, receptor autoradiography, and in situ hybridization techniques were employed to determine if dopaminergic receptors are located on cholinergic interneurons in the caudate-putamen (CPu). Lesion of the CPu with small amounts of the cholinotoxin AF64A resulted in a significant decrease in D2 receptor mRNA and D2 receptor binding. The loss was more pronounced in lateral and central portions of the CPu. Results obtained using [3H] SCH23390 binding to D1 receptors indicated that there was no change in this dopamine receptor subtype in the AF64A-lesioned CPu. A decrease in D2 receptor mRNA and receptor binding in AF64A-lesioned animals indicates that a population of postsynaptic D2 receptors is associated with the cholinergic interneurons. Lack of any change in [3H]SCH23390 binding in the AF64A-lesioned animals suggests that D1 receptors are not located on cholinergic neurons. These results provide evidence to support the selectivity of the lesion when used as indicated.

Interferon-gamma, but not interferon-alpha beta, synergizes with tumor necrosis factor-alpha and lipid A in the induction of nitric oxide production by murine L929 cells

Recently, we have demonstrated that tumor necrosis factor (TNF)-sensitive tumor cells produce nitric oxide (NO) in response to TNF whereas TNF-resistant cells do not. Because the addition of interferon-gamma (IFN-gamma) augmented NO production, we were interested in investigating this phenomenon further and comparing the effects of IFN-gamma with those of IFN-alpha beta. We found that cell lines that are sensitive to TNF-mediated cytotoxicity (TMC) produced NO in response to TNF and IFN-gamma, but not in response to IFN-alpha beta. The effect of IFN-gamma on NO production was dose dependent, but IFN-gamma by itself did not induce NO production. A TNF-resistant cell line (MCA) did not produce NO under any of the conditions tested. Different results were obtained when the effect of IFNs on TMC was assayed. TNF-sensitive L929 cells were rendered less sensitive to TNF after treatment with both types of IFN. In contrast, another TNF-sensitive cell, WEHI 164, was rendered more sensitive to TMC after treatment with both types of IFN. The effect of IFNs on WEHI cells was dose dependent. Neither IFN had any effect on TNF sensitivity of TNF-resistant MCA cells. The addition of lipid A (LA) had no effect on TMC under any condition. However, L929 cells treated with LA, TNF, and IFN-gamma produced twice as much NO as cells treated with TNF and IFN-gamma only. Northern analysis for cytokine-inducible NO synthase (NOS) mRNA steady-state levels indicated that TNF synergized with IFN-gamma to induce increased accumulation of NOS mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in the neuroendocrine control of growth hormone secretion in the uremic rat

Chronic renal insufficiency (CRI) is associated with growth failure in children and laboratory rats and is considered to be due, in part, to co-existent malnutrition. Alterations in hypothalamic control of growth hormone (GH) secretion have been suggested in uremic patients. We sought to determine whether factors unique to CRI play a role in this disturbance of GH regulation. Using in situ hybridization histochemistry, we compared messenger RNA (mRNA) levels for the hypothalamic neurohormones GH-releasing hormone (GHRH) and somatostatin (SRIH) in three groups: rats with CRI induced by 5/6 nephrectomy (NPX, N = 4); sham-operated, ad libitum fed rats (SAL, N = 5); and sham-operated, pair-fed rats (SPF, N = 5). We also measured plasma GH at 10 minute intervals for a six hour period via intra-atrial cannulae. The NPX group had significantly lower hypothalamic GHRH mRNA concentrations than both other groups; in addition, these levels were significantly lower in the SPF than in the SAL group. Concentrations of hypothalamic SRIH mRNA did not differ significantly among the three experimental groups. Six-hour mean plasma GH concentrations were significantly lower in the SPF (18.3 +/- 1.8 micrograms/liter) than in either the SAL (27.0 +/- 3.3 micrograms/liter) or the NPX groups (36.8 +/- 7.2 micrograms/liter); the difference in the mean plasma GH levels in the NPX vs. the SAL group did not attain statistical significance. This study provides evidence for an effect of CRI on the neuroendocrine control of GH secretion not related to caloric intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of increased gamma-aminobutyric acid levels on GAD67 protein and mRNA levels in rat cerebral cortex

Rats were injected with saline or the gamma-aminobutyric acid (GABA) transaminase inhibitor gamma-vinyl-GABA for 7 days and the effects on GABA content and glutamic acid decarboxylase (GAD) activity, and the protein and mRNA levels of the two forms of GAD (GAD67 and GAD65) in the cerebral cortex were studied. gamma-Vinyl-GABA induced a 2.3-fold increase in GABA content, whereas total GAD activity decreased by 30%. Quantitative immunoblotting showed that the decline in GAD activity was attributable to a 75-80% decrease in GAD67 levels, whereas the levels of GAD65 remained unchanged. RNA slot-blotting with a 32P-labeled GAD67 cDNA probe demonstrated that the change in GAD67 protein content was not associated with a change in GAD67 mRNA levels. Our results suggest that GABA specifically controls the level of GAD67 protein. This effect may be mediated by a decreased translation of the GAD67 mRNA and/or a change in the stability of the GAD67 protein.

Developmental expression of chicken antithrombin III is regulated by increased RNA abundance and intracellular processing

We isolated and sequenced a 432 bp cDNA to cAT-III, that encoded 115 nucleotides of 5' untranslated sequence, a 17 amino acid long signal peptide and residues 1-88 of the mature protein, and used it to prepare a probe for measuring and correlating the developmental changes of steady-state cAT-III mRNA levels with known changes in antigen levels. Densitometric analysis of nuclease protection (n = 2), Northern blot (n = 4), and slot blots (n = 3) of total RNA from chick livers of 16-day-old embryos to 6-day-old chicks showed a 2.6 +/- 0.5-fold increase in steady-state cAT-III mRNA levels. Assay of functional mRNA levels by in vitro translation of poly(A)+ RNA and specific immunoprecipitation of 35S-Met-labelled cAT-III was comparable to RNA analysis (16-day-old embryos vs. 10-day-old hatchlings). We evaluated whether there were developmental differences in post-translational secretion which may also contribute to the regulation of the circulating level of this protein. Pulse-chase studies of freshly-isolated hepatocytes from 16-day-old embryos and 10-day-old hatchlings maintained in suspension demonstrated a approx. 5.0-5.5-fold increase in cAT-III levels at steady-state secretion. The above findings indicate that changes in circulating cAT-III levels during late embryonic development are primarily due to increased abundance of cAT-III mRNA. In addition, we postulate that post-translational intracellular processing may account for further differences in circulating protein levels.

Genomic mapping of intracisternal A-particle proviral elements

Intracisternal A-particle (IAP) proviral elements are moderately reiterated and widely dispersed in the mouse genome. Oligonucleotide probes have been derived from three distinctive IAP element subfamilies (LS elements) that are transcriptionally active in normal mouse B- and T-cells. In HindIII digests, LS element-specific oligonucleotides each react with a limited number of restriction fragments that represent junctions between proviral and flanking DNA. These fragments have characteristic strain distribution patterns (SDPs) which are polymorphic in the DNAs of different mouse strains. We have established chromosomal assignments for 44 LS proviral loci by comparing their SDPs with those of known genetic markers in the BXD set of RI mouse strains. Some of the loci have also been scored in the CXB RI set. The IAP LS loci can provide a significant number of markers with a recognized genetic organization to the mouse genome map.

Postnatal ontogenesis of neurons containing GABAA alpha 1 subunit mRNA in the rat forebrain

The expression of GABAA receptor alpha 1 subunit mRNA in the postnatal rat forebrain was examined by in situ hybridization histochemistry. In most regions, including the isocortex, olfactory bulb, amygdala, septum, nucleus of the diagonal band, bed nucleus of the stria terminalis, basal ganglia, thalamus, and hypothalamus, the expression of alpha 1 subunit mRNA was low at birth but showed a dramatic increase during the early postnatal period. Adult levels of expression were reached at around the second or third week of life in these regions. However, in the caudate-putamen, and the nucleus accumbens, the expression of this subunit was only transient.

Induction of hepatic metallothionein by paraquat

Paraquat, a frequently used contact herbicide, produces oxidative stress by undergoing redox cycling and generating reactive oxygen species. Paraquat is also effective at increasing hepatic levels of metallothionein (MT). The mechanism(s) by which agents that induce oxidative stress produce increases in MT concentrations is not yet known. Therefore, the goal of the current study was to characterize the elevation in hepatic MT produced by paraquat administration to mice and to examine potential mechanism(s) of this increase. A dose-response study for increases in MT showed that administration of 0.1 to 0.5 mmol/kg of paraquat, sc, increased hepatic MT with a maximal increase of 36-fold. Subsequent studies were carried out with paraquat at a dose (0.3 mmol/kg, sc) that caused oxidative stress, as shown by a 35-fold increase in the biliary excretion of oxidized glutathione. There were coordinate elevations of both hepatic MT-I and MT-II mRNA of approximately 5-fold with peaks at both 6 and 24 hr after paraquat. The time course for the elevation in hepatic MT protein following paraquat treatment showed that MT levels had a maximal increase of 18-fold obtained at 36 hr. Paraquat appears to be an indirect MT inducer, in that there were no elevations in MT when cultured mouse hepatocytes were exposed to paraquat. No rise in liver Zn was observed prior to the increase in hepatic MT, thus, a Zn redistribution to the liver did not cause the increase in hepatic MT following paraquat administration. Adrenalectomy did not abolish the increase in MT produced by paraquat, suggesting that adrenal gland products are not required for the increase in MT produced by paraquat. In conclusion, the chemical mediator responsible for the increase in hepatic MT after paraquat was not determined, but the elevation in MT concentration appears to be due to increased transcription.

Selection of a muramyl peptide based on its lack of activation of nuclear factor-kappa B as a potential adjuvant for AIDS vaccines

Activation of the cellular transcription factor nuclear factor-kappa B (NF-kappa B) by cytokines and other immunostimulants has been tightly linked with enhanced replication of human immunodeficiency virus-type 1 (HIV-1) in infected cells. Various immunomodulators are currently being examined in animal and human trials for their suitability as adjuvants in potential vaccines against acquired immunodeficiency syndrome (AIDS). It may prove to be beneficial to select adjuvants that do not induce NF-kappa B activation and particularly if the vaccines are to be aimed at seropositive individuals. We have examined a battery of synthetic immunostimulants of the muramyl peptide family for their ability to activate NF-kappa B in human and mouse cell lines. In this report, we demonstrate selective activation of NF-kappa B in different cell lines and by different muramyl peptides possessing immunostimulatory activities. The mechanism of such activation is apparently via production of reactive oxygen intermediates (ROI) since pretreatment of cells with antioxidants blocked subsequent activation of NF-kappa B. However, among all the molecules tested only one lipophilic, non-pyrogenic adjuvant active muramyl peptide showed a complete lack of NF-kappa B activation in all cell lines tested. This molecule could well become the adjuvant of choice in future AIDS vaccines.

Hsp70 mRNA induction is reduced in neurons of aged rat hippocampus after thermal stress

Levels of heat-shock 70 mRNAs, relative to those of 18S rRNA, were quantitated in specific cell types of hippocampus of adult and aged rats subjected to identical heat shock regimens. Body temperature changes in response to the heat stress were no different in adult and aged rats. In control rats, as well as 3 h after initiation of heat shock in both adult and aged rats, relative levels of the constitutively synthesized heat-shock cognate 70 (hsc70) mRNA were highest in hippocampal neurons and much lower in glia. No heat-shock protein 70 (hsp70) mRNAs were present in any cell type of control adult or aged rats. In heat-shocked adult rats, the relative levels of the heat-shock-inducible hsp70 mRNAs were highest in a subpopulation of glia, intermediate in granule cells of the dentate gyrus, and lowest in pyramidal cells of Ammon's horn. Relative levels of hsp70 mRNA were several-fold lower in the dentate gyrus granule cells of aged rats compared to relative levels in controls and were also reduced in many pyramidal cells of the hippocampus but not in hippocampal glia. These findings suggest that some neuronal populations in the hippocampus may be at increased risk for stress-related injury in the aged animal.

Architecture of the vir regulons of group A streptococci parallels opacity factor phenotype and M protein class

Group A streptococci have traditionally been categorized into two broad groups based on the presence or absence of serum opacity factor (OF). Recent studies show that these two groups vary in a number of properties in addition to the OF phenotype, including sequence variations in the constant region of the antiphagocytic M protein genes, the presence or absence of immunoglobulin G Fc receptor proteins, and the presence or absence of multiple M protein-like genes situated in a tandem array. The M protein genes (emm) in OF- streptococcal strains are known to be part of a regulon of virulence-related genes controlled by the trans-acting positive regulatory gene, virR, situated just upstream of emm. In OF+ strains, however, the region adjacent to virR is occupied by an M protein-related, type IIa immunoglobulin G Fc receptor gene (fcrA), and the relative position of emm has not been determined. To further define the vir regulon in OF+ streptococci, we used the polymerase chain reaction to show that fcrA49 is situated immediately upstream of emm49 in the OF+ type 49 strain CS101. This result shows for the first time the separate identity and genetic linkage of these two genes in the vir regulon of an OF+ group A streptococcal strain and confirms our previous hypothesis that emm49 exists as the central gene in a trio of emm-like genes. Additionally, using DNA hybridizations, we found considerable sequence divergence between OF- and OF+ group A streptococci in virR and in the noncoding sequences between virR and the emm or fcrA expression site. We found, however, a high degree of sequence conservation in this region within each of the two groups of strains.

rRNA gene organization in the Lyme disease spirochete, Borrelia burgdorferi

Lyme disease is the most common vector-borne disease in the United States. The causative agent is the spirochete Borrelia burgdorferi. The copy number and organization of the genes encoding the rRNAs of this organism were determined. There is a single gene for 16S rRNA and two copies each of the 23S rRNA and 5S rRNA genes. All of the genes are located within a chromosomal fragment of approximately 9.5 to 10.0 kb. The 23S and 5S rRNA genes are tandemly duplicated in the order 23S-5S-23S-5S and are apparently not linked to the 16S rRNA gene, which is situated over 2 kb upstream from the 23S-5S duplication. The individual copies of the 23S-5S duplication are separated by a 182-bp spacer. Within each 23S-5S unit, an identical 22-bp spacer separates the 23S and 5S rRNA sequences from each other. The genome organization of the 23S-5S gene cluster in a number of different B. burgdorferi isolates obtained at a number of different geographical locations, as well as in several other species of Borrelia, was investigated. All isolates of B. burgdorferi tested displayed the tandem duplication, whereas the closely related species B. hermsii, B. anserina, and B. turicatae all contained a single copy of each of the genes. In addition, different geographical isolates of B. burgdorferi can be differentiated on the basis of a restriction fragment length polymorphism associated with the 23S-5S gene cluster. This polymorphism can be a useful tool for the determination of genetic relatedness between different isolates of B. burgdorferi.

Induction of metallothionein by diethyl maleate

Metallothionein (MT) is a sulfhydryl-rich protein whose levels are increased by administration of a variety of agents including metals, cytokines, and oxidative stress agents. Recent studies have suggested that MT is involved in protecting against various forms of oxidative stress, but little is known about the induction of MT by oxidative stress agents. Diethyl maleate (DEM) causes oxidative stress by depleting glutathione levels and is quite effective at increasing hepatic concentrations of MT. The purpose of the current study was to learn more about the relationship between induction of MT and oxidative stress by characterizing this increase in hepatic MT levels produced by DEM. Administration of DEM (3 to 9 mmol/kg, sc) increased hepatic MT concentration in mice as much as 37-fold to 213 micrograms MT/g liver, which is similar to the hepatic MT level seen after administration of other effective MT inducers, such as Cd. The maximal increase of hepatic MT took place 12 to 24 hr after administration of 5 mmol DEM/kg. This rise in MT was preceded by a 60% depletion of hepatic glutathione 3 hr after DEM and increases in both MT-I and MT-II mRNA, which reached a peak 6 to 9 hr after DEM. Administration of DEM (3-5 mmol/kg, sc) also increased MT levels in Sprague-Dawley rats. Pretreatment with DEM protected against Cd-induced hepatotoxicity in a fashion which suggested that a functional MT was being synthesized. In summary, DEM is a highly effective inducer of MT which increases MT at the mRNA level.

Aging related alterations in GABAA receptor subunit mRNA levels in Fischer rats

The influence of aging on the binding of ligands to picrotoxin binding sites as well as steady state levels of mRNA for various alpha subunits of gamma-aminobutyric acid (GABA) receptor complex was investigated in male Fischer F-344 rats. In aged rats, the binding of [35S]t-butyl-bicyclophosphorothionate (TBPS) was significantly reduced. This decrease in TBPS binding derived from a reduced density of binding sites, rather than from affinity changes, in both cerebral cortex and cerebellum. In aged rats, alpha 1 mRNA level decreased approximately 70% between age 6 months and 24 months in the cerebral cortex (P less than 0.005). In contrast, alpha 1 mRNA remained unchanged in the cerebellum of old rats. The association of a decrease in picrotoxin binding sites in the cerebral cortex with a decline in alpha 1 mRNA level in the cerebral cortex and in alpha 2 mRNA level in the cerebellum is indicated. alpha 6 mRNA level increased with age in the cerebellum. These findings indicate a selective age related modulation in the stoichiometry of GABAA receptor in aging.

Effects of butyrate homologues on metallothionein induction in rat primary hepatocyte cultures

Sodium butyrate (NaB), a 4-carbon fatty acid, has been reported to activate the metallothionein (MT) gene in certain carcinoma cell lines. Because the effects of NaB are dependent on the cell type investigated, this study was conducted to determine if NaB and its homologues induce MT in rat primary hepatocyte cultures. Hepatocytes were grown on monolayer for 12 h and subsequently treated with formate, acetate, propionate (NaP), NaB, and valeric acid for 10 to 58 h. To examine their interaction with known MT inducers, cadmium (Cd), zinc (Zn), or dexamethasone (Dex) were added to some cultures. MT protein in the cells was quantitated by the Cd-hemoglobin assay; MT-1 mRNA was analyzed by Northern blot hybridizations with oligonucleotide probes, and quantitated by slot-blot analysis. Among the 1 to 5 carbon carboxylic acids, only NaP (3 carbon) and NaB (4 carbon) induced MT. NaP and NaB alone produced a moderate increase in MT two- to fourfold over control), but when combined with Cd or Dex, an additive increase was observed. However, when combined with Zn, a synergistic increase was detected. NaB and Zn synergistically increased MT protein, but produced only an additive increase in MT mRNA, suggesting the involvement of some posttranscriptional event(s) in the NaB-Zn induction of MT. In conclusion, NaP and NaB induced MT in normal cultured rat hepatocytes, producing an additive increase in MT protein with Cd and Dex, and a synergistic increase in MT protein with Zn.

Somatotopic organization of tyrosine hydroxylase expression in the rat locus coeruleus: long term effect of RU24722

Tyrosine hydroxylase (TH) tissue concentration was determined by immunostaining of tissue sections directly transferred onto nitrocellulose membranes in the restricted region of the noradrenergic perikarya of the locus coeruleus (LC) along its postero-anterior axis. TH containing cells were systematically counted on adjacent post fixed sections stained by immunohistochemistry. The absolute quantity of TH was estimated in each section and was found to be linearly related to the number of TH immuno-positive cells found in the adjacent section. The ratio between these two parameters was thus used as an index of the cellular concentration of TH in noradrenergic cells. In the LC of control rats, the TH cellular concentration was lower (-39%) in the anterior than in the posterior half of the structure. Three days after an injection of 20 mg/kg of RU24722, an eburnamine derivative known to increase the quantity of TH in the LC, increases in quantities of TH were found in both portions of the LC. Moreover in the posterior LC the increase in the amount of TH resulted from a significant increase in the number of TH-immunopositive cells. In the anterior part, however, it was primarily the result of a significant increase in TH cellular concentration. Throughout the LC there was an increase in the cellular concentration of TH which was inversely proportional to the concentrations found in control animals. TH mRNA content was measured by a quantitative in situ hybridization in sections of both the posterior and anterior LC one day after a single injection of RU24722 at the same dose. The quantity of TH mRNA was significantly increased in both parts. The number of TH mRNA-expressing neurons also increased, especially in the anterior LC. Thus the effects at the level of TH protein and TH mRNA were strikingly parallel though increase in TH protein occurred later than the increase in the TH mRNA. These results suggest that in the rat LC: (1) there is a significant population of 'sleeping cells' in which TH expression is either inactivated or, at a low level of activation; (2) TH cellular concentration could exert a retrocontrol on its own expression in cells of the LC that contained TH and (3) TH expression appears to be regulated by different selective mechanisms in these two different subpopulations of noradrenergic cells within the LC.

Characterization of cat messenger RNA decay suggests that turnover occurs by endonucleolytic cleavage in a 3' to 5' direction

Turnover of the chloramphenicol acetyltransferase (cat) messenger RNA in Escherichia coli was investigated by analysis of cellular mRNA decay intermediates and the transcript sequence. Analysis of the sequence has revealed the presence of a repetitive extragenic palindromic (REP) element at the 3' end of the transcript as well as several 5'-UUAU-3' sequences, two elements which have roles in modulating turnover of other E. coli mRNAs. For cat mRNA, however, removal of the REP sequence has no effect on the half-life of the transcript, indicating that the REP sequence does not stabilize the upstream region of this message. Results from mapping of the mRNA decay products by several techniques suggest that the message is instead subject to endonucleolytic attack at five sites 5' of the REP element. The sequence UUAU is present at three of these five sites. It also appears that the cat mRNA is sequentially cleaved in a 3' to 5' direction during turnover of this mRNA in vivo. A model for cat mRNA turnover is discussed.

Specific inhibition of mRNA accumulation for lymphokines in human T cell line Jurkat by mycobacterial lipoarabinomannan antigen

The immunomodulatory effect of Mycobacterium tuberculosis-derived lipoarabinomannan (LAM) on mitogen/antigen-induced expression of mRNAs for a number of cytokines in human monocytic cell line Mono-Mac-6 and in T cell line Jurkat was investigated. Interestingly, LAM exhibited a down-regulatory effect on the accumulation of mRNAs for IL-2, IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-2 receptor alpha (IL-2R alpha) in T cells co-stimulated with phytohaemagglutinin-P (PHA) and 4 beta-phorbol-12-myristyl-13-acetate (PMA). In human Mono-Mac-6 cells. LAM has a weak inhibitory effect on the lipopolysaccharide (LPS)-induced mRNA accumulation for IL-1 beta, a slight stimulatory effect on mRNAs accumulation for IL-8 and tumour necrosis factor-alpha (TNF-alpha), but clearly no effect on mRNA accumulation for intercellular adhesion molecule-1 (ICAM-1). These findings imply that LAM may contribute to the immunologic defects associated with a number of mycobacterial infections by modulating these mediators.

Distribution of cadmium chloride and cadmium-metallothionein to liver parenchymal, Kupffer, and endothelial cells: their relative ability to express metallothionein

Acute exposure to cadmium (Cd) salts results in liver toxicity, while administration of cadmium-metallothionein (CdMT) iv, causes renal damage. When CdMT is administered iv there is a rapid accumulation of Cd in the proximal tubule cells of the kidney. In comparison, only small amounts of Cd accumulate in the liver following administration of CdMT. Thus, in order to better understand the regulation of MT as well as the toxicity of Cd, the present study has examined the ability of each of the three primary liver cells, parenchymal (PC), Kupffer (KC), and endothelial (EC), to accrue Cd after administration of either inorganic or organic forms of Cd. In addition, the relative ability of each cell type to express metallothionein (MT) mRNA and protein was examined. Following CdCl2 (3.5 mg Cd/kg) treatment, Cd concentrations increased to about the same degree in PC and KC, but EC had about 2-fold more than PC. After administration of CdCl2 (1.0 mg Cd/kg) each cell responded to the presence of Cd by increasing intracellular MT mRNA and protein. However, PC showed the greatest response, with a 30-fold increase in mRNA and a 21-fold increase in protein. Interestingly, KC and EC possessed intracellular Cd concentrations equal to or greater than that of PC, but contained less MT than would have been expected on the basis of their intracellular Cd concentrations. Thus, KC had a 7-fold increase in MT mRNA and a 2-fold increase in protein, while EC increased mRNA 3-fold and protein 2-fold over control values. In contrast, following CdMT (0.5 mg Cd/kg) administration, only low levels of Cd were detected, with similar concentrations in each cell type. After administration of CdMT (0.4 mg Cd/kg), PC again showed the greatest response, with a 3-fold increase in mRNA and a 6-fold increase in MT protein. Only slight changes were observed in KC and EC. In conclusion, the present study has shown the following: (1) Endogenous levels of MT in KC and EC are higher than those in PC. (2) Cd is readily accumulated by all three cell types, when administered as CdCl2, but not when given as CdMT. (3) PC, KC, and EC are capable of responding to intracellular Cd by increasing MT.

Induction of metallothionein by cadmium-metallothionein in rat liver: a proposed mechanism

Distribution of Cd to various organs following iv administration of CdCl2 (3.5 mg Cd/kg) resulted in more than 43% of total tissue Cd accumulating in the liver. In contrast, after CdMT administration (0.5 mg Cd/kg), only 1% of the Cd was found in liver. Rats administered CdCl2 (1.0 mg Cd/kg) had hepatic MT values 30-fold greater than controls and a hepatic Cd concentration of 17 micrograms/g. In comparison, rats treated with CdMT (0.4 mg Cd/kg) had hepatic MT concentrations 7-fold greater than controls and a hepatic Cd concentration of 0.80 micrograms/g. However, when hepatic MT levels were normalized to tissue Cd concentrations, induction of MT by CdMT was 5-fold greater than by CdCl2. Northern and slot-blot analyses of mRNA showed that both CdCl2 and CdMT coordinately increased MT mRNA. These data suggest that both CdMT and CdCl2 increase hepatic MT by similar mechanisms. A dose-response increase in MT produced by CdCl2 indicated a biphasic response, with low doses producing relatively more hepatic MT than higher doses. In addition, the amount of MT produced per unit Cd after CdMT treatment was similar to those observed after low doses of CdCl2 in the dose-response experiment. These data provide strong evidence to support the conclusion that the apparent potency of CdMT observed here and in previous studies is most likely due to the small amount of Cd distributed to the liver, which is relatively more effective in inducing MT than are higher concentrations.