Isolation and characterization of full-length cDNA clones for human alpha-, beta-, and gamma-actin mRNAs: skeletal but not cytoplasmic actins have an amino-terminal cysteine that is subsequently removed

Structural and functional analysis of actin point mutations leading to nemaline myopathy to elucidate their role in actin function

In this work, we analyzed 78 mutations in the actin protein that cause the disease nemaline myopathy. We analyzed how these mutations are distributed in important regions of the actin molecule (folding nucleus, core of the filament, amyloidogenic regions, disordered regions, regions involved in interaction with other proteins). It was found that 54 mutations (43 residues) fall into the folding nucleus (Ф ≥ 0.5), 11 mutations (10 residues) into the filament core, 14 mutations into the amyloidogenic regions (11 residues), 14 mutations (9 residues) in the unstructured regions, and 24 mutations (22 residues) in regions involved in interaction with other proteins. It was also found that the occurrence of single mutations G44V, V45F, T68I, P72R, K338I and S350L leads to the appearance of new amyloidogenic regions that are not present in native actin. The largest number of mutations (54 out of 78) occurs in the folding nucleus; these mutations are important for folding and therefore can affect the protein folding rate. We have shown that almost all of the considered mutations are associated with the structural characteristics of the actin molecule, and some of the residues we have considered have several important characteristics.

Bioinformatics Analysis of Actin Molecules: Why Quantity Does Not Translate Into Quality?

It is time to review all the available data and find the distinctive characteristics of actin that make it such an important cell molecule. The presented double-stranded organization of filamentous actin cannot explain the strong polymorphism of actin fibrils. In this work, we performed bioinformatics analysis of a set of 296 amino acid actin sequences from representatives of different classes of the Chordate type. Based on the results of the analysis, the degree of conservatism of the primary structure of this protein in representatives of the Chordate type was determined. In addition, 155 structures of rabbit actin obtained using X-ray diffraction analysis and electron microscopy have been analyzed over the past 30 years. From pairwise alignments and the calculation of root-mean-square deviations (RMSDs) for these structures, it follows that they are very similar to each other without correlation with the structure resolution and the reconstruction method: the RMSDs for 11,781 pairs did not exceed 3 Å. It turned out that in rabbit actin most of the charged amino acid residues are located inside the protein, which is not typical for the protein structure. We found that two of six exon regions correspond to structural subdomains. To test the double-stranded organization of the actin structure, it is necessary to use new approaches and new techniques, taking into account our new data obtained from the structural analysis of actin.

Structural insights into SETD3-mediated histidine methylation on β-actin

SETD3 is a member of the SET (Su(var)3–9, Enhancer of zeste, and Trithorax) domain protein superfamily and plays important roles in hypoxic pulmonary hypertension, muscle differentiation, and carcinogenesis. Previously, we identified SETD3 as the actin-specific methyltransferase that methylates the N3 of His73 on β-actin (Kwiatkowski et al., 2018). Here, we present two structures of S-adenosyl-L-homocysteine-bound SETD3 in complex with either an unmodified β-actin peptide or its His-methylated variant. Structural analyses, supported by biochemical experiments and enzyme activity assays, indicate that the recognition and methylation of β-actin by SETD3 are highly sequence specific, and that both SETD3 and β-actin adopt pronounced conformational changes upon binding to each other. In conclusion, this study is the first to show a catalytic mechanism of SETD3-mediated histidine methylation on β-actin, which not only throws light on the protein histidine methylation phenomenon but also facilitates the design of small molecule inhibitors of SETD3.

Production of Human β-Actin Using a Bacterial Expression System with a Cold Shock Vector

Actin is one of the most abundant proteins in the cytoplasm of eukaryotic cells and plays important roles in a variety of cellular functions. However, it has been difficult to produce actin in substantial amounts using bacterial expression systems. In this article, a new method is described for the production of recombinant actin in bacterial cells. Human β-actin (His-tagged) can be expressed using a cold shock vector, pCold, in a bacterial expression system and then separated with a Ni-chelating resin, followed by a polymerization/depolymerization cycle or column chromatography with the Ni-chelating resin. The purified recombinant β-actin shows normal polymerization ability compared with commercially available β-actin purified from human platelets. This article also describes the preparation of mutant actin(G168R). This purified mutant exhibits impaired polymerization ability. The system and procedures described here will provide a useful method for the production of actin isoforms and their mutants. © 2018 by John Wiley & Sons, Inc.

The makings of the 'actin code': regulation of actin's biological function at the amino acid and nucleotide level

The actin cytoskeleton plays key roles in every eukaryotic cell and is essential for cell adhesion, migration, mechanosensing, and contractility in muscle and non-muscle tissues. In higher vertebrates, from birds through to mammals, actin is represented by a family of six conserved genes. Although these genes have evolved independently for more than 100 million years, they encode proteins with ≥94% sequence identity, which are differentially expressed in different tissues, and tightly regulated throughout embryogenesis and adulthood. It has been previously suggested that the existence of such similar actin genes is a fail-safe mechanism to preserve the essential function of actin through redundancy. However, knockout studies in mice and other organisms demonstrate that the different actins have distinct biological roles. The mechanisms maintaining this distinction have been debated in the literature for decades. This Review summarizes data on the functional regulation of different actin isoforms, and the mechanisms that lead to their different biological roles in vivo We focus here on recent studies demonstrating that at least some actin functions are regulated beyond the amino acid level at the level of the actin nucleotide sequence.

The two mutations of actin-myosin interface and their effect on the dynamics, structures, and functions of skeletal muscle actin

Congenital myopathy is a broad category of muscular diseases with symptoms appearing at the time of birth. One type of congenital myopathy is Congenital Fiber Type Disproportion (CFTD), a severely debilitating disease. The G48D and G48C mutations in the D-loop and the actin-myosin interface are the two causes of CFTD. These mutations have been shown to significantly affect the structure and function of muscle fibers. To the author's knowledge, the effects of these mutations have not yet been studied. In this work, the power stroke structure of the head domain of myosin and the wild and mutated types of actin were modeled. Then, a MD simulation was run for the modeled structures to study the effects of these mutations on the structure, function, and molecular dynamics of actin. The wild and mutated actins docked with myosin showed differences in hydrogen bonding patterns, free binding energies, and hydrogen bond occupation frequencies. The G48D and G48C mutations significantly impacted the conformation of D-loops because of their larger size compared to Glycine and their ability to interfere with the polarity or hydrophobicity of this neutralized and hydrophobic loop. Therefore, the mutated loops were unable to fit properly into the hydrophobic groove of the adjacent G-actin. The abnormal structure of D-loops seems to result in the abnormal assembly of F-actins, giving rise to the symptoms of CFTD. It was also noted that G48C and G48D did not form hydrogen bonds with myosin in the residue 48 location. Nevertheless, in this case, muscles are unable to contract properly due to muscle atrophy.

Inhibition of Formation of Rev-RRE Complex by Pyronin Y

The interaction of pyronin Y, an RNA intercalating drug, with the binding of Rev protein from human immunodeficiency virus type 1 (HIV-1) to Rev-responsive element (RRE)-containing env RNA was studied. In gel retardation assays, recombinant Rev protein tightly bound to in vitro transcribed RRE RNA. Nitrocellulose-filter-binding studies revealed a dissociation constant of ≈(1–2) = 10−10M (Pfeifer et al., 1991). Pyronin Y efficiently suppressed formation of the Rev-RRE complex. At a concentration of 1 μg ml−1, complex formation was almost completely inhibited. Electron microscopy showed that Rev oligomerizes in the presence of RRE-containing RNA with the formation of short rod-like structures or long filaments, depending on the length of the transcript. Assembly of Rev protein along RRE-containing RNAs was abolished after addition of pyronin Y. Thus pyronin Y represents the first compound described to inhibit Rev-RRE complex formation.

Identification of stable reference genes for quantitative PCR in cells derived from chicken lymphoid organs

Quantitative polymerase chain reaction (qPCR) is a powerful technique for quantification of gene expression, especially genes involved in immune responses. Although qPCR is a very efficient and sensitive tool, variations in the enzymatic efficiency, quality of RNA and the presence of inhibitors can lead to errors. Therefore, qPCR needs to be normalised to obtain reliable results and allow comparison. The most common approach is to use reference genes as internal controls in qPCR analyses. In this study, expression of seven genes, including β-actin (ACTB), β-2-microglobulin (B2M), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-glucuronidase (GUSB), TATA box binding protein (TBP), α-tubulin (TUBAT) and 28S ribosomal RNA (r28S), was determined in cells isolated from chicken lymphoid tissues and stimulated with three different mitogens. The stability of the genes was measured using geNorm, NormFinder and BestKeeper software. The results from both geNorm and NormFinder were that the three most stably expressed genes in this panel were TBP, GAPDH and r28S. BestKeeper did not generate clear answers because of the highly heterogeneous sample set. Based on these data we will include TBP in future qPCR normalisation. The study shows the importance of appropriate reference gene normalisation in other tissues before qPCR analysis.

Hormonal regulation and characterization of MHG30 gene, a desaturase-like gene of hamster harderian gland

The harderian gland (HG) is an orbital gland of the vast majority of land vertebrates. In the Syrian hamster these glands display a marked sexual dimorphism. Here we present data on a male specific clone named MHG30. The MHG30 cDNA (1470 bp) has significant sequence homologies with human #15μ10#Δ6-desaturase enzymes. The expression of MHG30 has been found in male HG and in the liver of both sexes, no other tissue showing the presence of MHG30 mRNA. Castration brings the MHG30 levels below detectable level in about 7 days. In in vitro cultures of male hamster HG cells, androgens (A) determine an enhancement of MHG30 expression in a time-dependent manner. Conversely, a continuous decrement has been observed in control cells and in cells treated with A plus flutamide (F) or with A and cycloheximide (Cy). Incubation of cells in cultures supplemented with desamethason (Dex) or thyroid hormone (T3) also increases MHG30 expression while 17β-estradiol prevents the stimulatory effect exerted by A, Dex and T3. Findings strongly suggest that the MHG30 gene could be involved in supporting the sexual dimorphism and its expression is likely triggered by a series of hormonal interactions.

Systematic functional genomics resource and annotation for poplar

Poplar, as a model species for forestry research, has many excellent characteristics. Studies on functional genes have provided the foundation, at the molecular level, for improving genetic traits and cultivating elite lines. Although studies on functional genes have been performed for many years, large amounts of experimental data remain scattered across various reports and have not been unified via comprehensive statistical analysis. This problem can be addressed by employing bioinformatic methodology and technology to gather and organise data to construct a Poplar Functional Gene Database, containing data on 207 poplar functional genes. As an example, the authors investigated genes of Populus euphratica involved in the response to salt stress. Four small cDNA libraries were constructed and treated with 300 mM NaCl or pure water for 6 and 24 h. Using high-throughput sequencing, they identified conserved and novel miRNAs that were differentially expressed. Target genes were next predicted and detailed functional information derived using the Gene Ontology database and Kyoto Encyclopedia of Genes and Genomes pathway analysis. This information provides a primary visual schema allowing us to understand the dynamics of the regulatory gene network responding to salt stress in Populus.

Neuromuscular electrical stimulation training induces atypical adaptations of the human skeletal muscle phenotype: a functional and proteomic analysis

The aim of the present study was to define the chronic effects of neuromuscular electrical stimulation (NMES) on the neuromuscular properties of human skeletal muscle. Eight young healthy male subjects were subjected to 25 sessions of isometric NMES of the quadriceps muscle over an 8-wk period. Needle biopsies were taken from the vastus lateralis muscle before and after training. The training status, myosin heavy chain (MHC) isoform distribution, and global protein pattern, as assessed by proteomic analysis, widely varied among subjects at baseline and prompted the identification of two subgroups: an "active" (ACT) group, which performed regular exercise and had a slower MHC profile, and a sedentary (SED) group, which did not perform any exercise and had a faster MHC profile. Maximum voluntary force and neural activation significantly increased after NMES in both groups (+∼30% and +∼10%, respectively). Both type 1 and 2 fibers showed significant muscle hypertrophy. After NMES, both groups showed a significant shift from MHC-2X toward MHC-2A and MHC-1, i.e., a fast-to-slow transition. Proteomic maps showing ∼500 spots were obtained before and after training in both groups. Differentially expressed proteins were identified and grouped into functional categories. The most relevant changes regarded 1) myofibrillar proteins, whose changes were consistent with a fast-to-slow phenotype shift and with a strengthening of the cytoskeleton; 2) energy production systems, whose changes indicated a glycolytic-to-oxidative shift in the metabolic profile; and 3) antioxidant defense systems, whose changes indicated an enhancement of intracellular defenses against reactive oxygen species. The adaptations in the protein pattern of the ACT and SED groups were different but were, in both groups, typical of both resistance (i.e., strength gains and hypertrophy) and endurance (i.e., a fast-to-slow shift in MHC and metabolic profile) training. These training-induced adaptations can be ascribed to the peculiar motor unit recruitment pattern associated with NMES.

Expression of Oestrogen Receptor and Transforming Growth Factor-α in MCF-7 Cells after Exposure to Fractionated Irradiation

The expression of critical growth controlling genes was studied in MCF-7 cells after exposure to cumulative radiation doses of 20 and 60 Gy yielding cell lines called MCF-IR-1 and MCF-IR-3, respectively. The irradiated cell lines exhibited increased plating efficiencies but no differences in growth rates. MCF-IR-1/-IR-3 cells showed a reduced oestrogen responsiveness as indicated by their diminished response to tamoxifen-induced growth arrest and 17 beta-oestradiol (E2)-induced growth stimulation. The reduced expression of oestrogen receptor (ER) was determined by quantitative immune peroxidase staining of single cells and by total cellular E2 binding. There was also a radiation dose-dependent increase in the radiosensitivity of MCF-IR-3 cells as determined by the radiobiological parameters alpha, beta, and D (mean inactivation dose). Using RNA protection assays the irradiated cell lines produced steady-state ER mRNA at reduced levels while the levels of TGF-alpha were unchanged in MCF-IR-1 cells but increased 2.8-fold in MCF-IR-3 cells. A similar pattern was seen for TGF-alpha protein. While the current analyses cannot differentiate between radiation-induced altered gene expression or cell selection the results demonstrate that reduced ER expression and increased TGF-alpha expression are associated with the survival of MCF-7 cells after fractionated irradiation in vitro. In contrast, the MCF-IR cells were found to be more radiosensitive in acute survival experiments.

Hormonal regulation and characterisation of the aldehyde oxidase-like gene of hamster Harderian gland

The HG is a compound tubulo-alveolar gland located in the orbital cavity of the majority of vertebrates. In the golden hamster it shows a clear cut sexual dimorphism in both morphological and biochemical parameters such as cell types, protein pattern, lipid metabolism, porphyrin content, steroid hormone receptor expression. In a previous study we found that in primary culture of male hamster Harderian gland (HG), androgens (A) increase the MHG07 (male Harderian gland) expression and this effect is abrogated by both flutamide and cycloheximide. The present study represents a deeper analysis on MHG07 regulation by other members of steroid/thyroid hormone superfamily. Estrogens (E) impair the stimulatory effect of A and after the addition of a pure anti-estrogen, ICI 164,384, the negative effect of E is abrogated. Dexamethasone (Dex), used alone or in combination with A negatively affect the MHG07 expression. Also T(3) increases the expression of MHG07 mRNA. Progesterone (P) does not affect the expression of MHG07 mRNA. The use of cycloheximide abrogates the effect of steroids, suggesting that the latter act through their own receptors. Dose-response experiments show that low steroid concentrations (10(-12)M) are sufficient to affect the MHG07 expression. It is argued that the expression of MHG07 is under a highly coordinate relationship between androgen, estrogen, glucocorticoid, retinoic acid and thyroid hormones.

Multi-gene gateway clone design for expression of multiple heterologous genes in living cells: modular construction of multiple cDNA expression elements using recombinant cloning

Much attention has been focused on manipulating multiple genes in living cells for analyzing protein function. In order to perform high-throughput generation of multi-gene expression clones, gateway cloning technology (which represents a high-throughput DNA transfer from vector to vector) can be anticipated. In the conventional strategy for gateway cloning, the construction of two or more expression elements into tandem elements on a single plasmid requires the recombination of multiple entry clones with a destination vector in a single reaction mixture. Use of increasing numbers of entry clones in a single reaction is inefficient due to the difficulty in successfully recognizing multiple pairs of matched att signals simultaneously. To address this problem, a "Modular Destination" vector has been devised and constructed, whereby cDNA inserts are sequentially introduced, resulting in a tandem structure with multiple inserts. Whereas the standard destination vector contains only Cm(R) and ccdB genes flanked by two attR signals, this destination vector contains, in addition, one or two cDNA expression elements. Here, we show the rapid construction of expression vectors containing three or four tandemly arrayed cDNA expression elements and their expression in mammalian cells.

Further studies of the distribution of CDF/LIF mRNA

Differentiation choices in the haemopoietic and nervous systems are controlled in part by instructive factors. The cholinergic differentiation factor (CDF, also known as leukaemia inhibitory factor, LIF) affects the development of cultured cells from both systems. To understand the role of CDF/LIF during normal development in vivo, we have begun to localize its mRNA in the late fetal and postnatal rat. Application of reverse transcriptase-polymerase chain reaction and RNase protection methods reveals that CDF/LIF mRNA levels are developmentally modulated in both haemopoietic and neural tissues. A target tissue of cholinergic sympathetic neurons, the footpads that contain the sweat glands, express high levels of this mRNA (relative to mRNA for actin and beta 2-microglobulin). Levels in targets of noradrenergic neurons are lower, but do undergo significant changes during development. Signals are also detected in selective regions of the adult brain, and in embryonic skeletal muscle. This finding in muscle may be significant for motor neurons, because CDF/LIF is a trophic factor for these neurons in culture. Embryonic liver, neonatal thymus and postnatal spleen express CDF/LIF mRNA, and expression in gut is the highest of all tissues examined. The selective tissue distribution and developmental modulation of CDF/LIF mRNA expression support a role for this factor in the normal development of several organ systems.

Human type 2 17 beta-hydroxysteroid dehydrogenase mRNA and protein distribution in placental villi at mid and term pregnancy

BACKGROUND

During human pregnancy, the placental villi produces high amounts of estradiol. This steroid is secreted by the syncytium, which is directly in contact with maternal blood. Estradiol has to cross placental foetal vessels to reach foetal circulation. The enzyme 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD2) was detected in placental endothelial cells of foetal vessels inside the villi. This enzyme catalyzes the conversion of estradiol to estrone, and of testosterone to androstenedione. It was proposed that estradiol level into foetal circulation could be regulated by 17beta-HSD2.

METHODS

We obtained placentas from 10 to 26 6/7 weeks of pregnancy from women undergoing voluntary termination of pregnancy, term placentas were collected after normal spontaneous vaginal deliveries. We quantified 17beta-HSD2 mRNA levels in mid-gestation and term human placenta by RT-QPCR. We produced a new anti-17beta-HSD2 antibody to study its spatio-temporal expression by immunohistochemistry. We also compared steroid levels (testosterone, estrone and estradiol) and 17beta-HSD2 mRNA and protein levels between term placenta and endometrium.

RESULTS

High 17beta-HSD2 mRNA and protein levels were found in both mid-gestation and term placentas. However, we showed that 17beta-HSD2 mRNA levels increase by 2.27 fold between mid-gestation and term. This period coincides with a transitional phase in the development of the villous vasculature. In mid-gestation placenta, high levels of 17beta-HSD2 were found in mesenchymal villi and immature intermediate villi, more precisely in endothelial cells of the stromal channel. At term, high levels of 17beta-HSD2 were found in the numerous sinusoidal capillaries of terminal villi. 17beta-HSD2 mRNA and protein levels in term placentas were respectively 25.4 fold and 30 to 60 fold higher than in the endometrium. Steroid levels were also significantly higher in term placenta than in the endometrium.

CONCLUSION

The spatial and temporal expression of 17beta-HSD2 in the placenta during pregnancy and the comparison of 17beta-HSD2 expression and steroid levels between placental villi and endometrium are compatible with a role in the modulation of active and inactive forms of estrogens. Our observations strongly support the hypothesis that 17beta-HSD2 acts as a barrier decreasing estradiol secretion rates in the foetal circulation.

Sulindac induces specific degradation of the HPV oncoprotein E7 and causes growth arrest and apoptosis in cervical carcinoma cells

Sulindac, a nonsteroidal anti-inflammatory drug (NSAID), induces growth arrest in HeLa cells and causes strong inhibition of the G1 to S transition of the cell cycle in a concentration-dependent manner. The G1 arrest is preceded by suppression of cyclin E and A, inactivation of cdk2, and the complete loss of the viral oncoprotein E7, despite ongoing HPV transcription. As shown by inhibitors specific for cyclooxygenase (COX) 1 and 2 loss of E7 is COX-independent. Moreover, inhibition of the proteasome activity with MG132 partially blocked the ability of sulindac to suppress E7 suggesting that sulindac induces degradation of E7 by the proteasomal pathway. In addition to inhibiting growth, sulindac strongly induces apoptosis, which can be abrogated by using the general caspase inhibitor zVAD-fmk. Unchanged expression of the pro-apoptotic protein Bax and suppression of the anti-apoptotic molecules Bcl-2 and Bcl-x(L) argues for the engagement of the mitochondrial apoptotic pathway. These results support the notion that sulindac is a potent growth inhibitor and inducer of apoptosis on cervical cancer cells in vitro and may offer new perspectives as a chemopreventive or supplementary anti-cervical cancer drug.

Role of serotonin in the regulation of the dynorphinergic system by a kappa-opioid agonist and cocaine treatment in rat CNS

It has been shown that chronic cocaine increases prodynorphin mRNA in the caudate putamen and decreases it in the hypothalamus. In addition, treatment with a kappa-opioid receptor agonist produced the opposite effect on prodynorphin gene expression in these brain regions and also evoked a decrease in the hippocampus. It is already known that kappa-opioid receptor agonists decrease the development of sensitization to some of the behavioral effects of cocaine. The serotonin system has also been shown to regulate dynorphin gene expression and a continuous infusion of fluoxetine induced prodynorphin gene expression in the same pattern as the kappa-opioid agonist (+)(5a,7a,8b)-N-methyl-N-[7-(1-pyrrolidinyl)-1 oxaspiro[4.5]dec-8-yl]-benzeneacetamide (U-69593) in the brain regions investigated. It is interesting to note that treatment with a continuous infusion of cocaine produced different effects on this parameter. To determine whether serotonin plays a role in the regulation of prodynorphin mRNA by kappa-opioid agonists or cocaine, rats were treated with the serotonin depleter parachloroamphetamine (PCA). Beginning 24 h later, rats were treated with the selective kappa-opioid agonist U-69593 for 5 days or continuously with cocaine for 7 days and prodynorphin mRNA was measured. Prodynorphin mRNA was decreased significantly in the hypothalamus, caudate putamen, and hippocampus of rats treated with a single injection of PCA. Subsequent to PCA administration the effects of U-69593 or cocaine on prodynorphin mRNA were differentially affected across brain regions. Prodynorphin gene expression was still increased by U-69593 treatment in the hypothalamus and decreased in the caudate putamen. Cocaine treatment still produced a decrease in this parameter in the hypothalamus and an increase in the caudate putamen. In contrast, in the hippocampus, the decrease in prodynorphin mRNA produced by U-69593 was no longer evident after PCA and cocaine, which previously had no effect, now increased it in the serotonin-depleted group. These findings suggest that serotonin is necessary to maintain normal levels of dynorphin mRNA in all of the investigated brain areas and that the regulation of prodynorphin mRNA expression by chronic treatment with a kappa-opioid receptor agonist or cocaine requires serotonin in the hippocampus, but not in the hypothalamus or caudate putamen.

Alterations in gamma-actin and tubulin-targeted drug resistance in childhood leukemia

BACKGROUND

Proteomic investigations have revealed alterations in cytoskeletal proteins expressed in human acute lymphoblastic leukemia cells that are resistant to microtubule-disrupting agents. We characterized gamma-actin expression in antimicrotubule drug-resistant leukemia and examined the effect of altered gamma-actin in resistance of acute lymphoblastic leukemia to antimicrotubule agents.

METHODS

Two-dimensional polyacrylamide gel electrophoresis and mass spectrometry were used to identify actin proteins in human acute lymphoblastic leukemia cell lines resistant to vinblastine (CCRF-CEM/VLB100 cells) and desoxyepothilone B (CCRF-CEM/dEpoB140 cells). Fluorescence-based cycle sequencing was used to detect gene mutations. Site-directed mutagenesis was used to generate mutant gamma-actin expression plasmids, which were used to transfect mouse NIH/3T3 cells. Clonogenic analysis was used for drug sensitivity studies. A small interfering RNA (siRNA) was used to block gamma-actin gene expression in human neuroblastoma SH-EP cells. Expression of gamma-actin (normalized to that of beta2-microglobulin [beta2M]) in primary leukemia cells obtained from patients at diagnosis (n = 44) and relapse (n = 25) was examined using semiquantitative reverse transcription-polymerase chain reaction. Statistical significance of changes in the ratio of gamma-actin to beta2M expression between diagnosis and relapse samples was determined by two-sided unpaired Student's t tests.

RESULTS

We identified novel mutant forms of gamma-actin and the concomitant loss of wild-type gamma-actin in CCRF-CEM/VLB100 cells and CCRF-CEM/dEpoB140 cells. Mouse NIH/3T3 cells that expressed the mutant gamma-actin proteins were more resistant to antimicrotubule agents than cells transfected with empty plasmid. Human neuroblastoma SH-EP cells transfected with gamma-actin siRNA displayed higher relative resistance to paclitaxel (P<.001), vinblastine (P = .04), and epothilone B (P = .045) than mock-transfected cells. No gamma-actin gene mutations were identified in 37 samples of primary leukemia cells (eight from patients at diagnosis, 29 from patients at relapse). Gamma-actin gene expression was lower in acute lymphoblastic leukemia samples collected at clinical relapse (n = 25; mean gamma-actin/beta2M = 0.53) than in samples collected at diagnosis (n = 44; mean gamma-actin/beta2M = 0.68; difference = 0.15, 95% confidence interval [CI] = 0.04 to 0.27, P = .01).

CONCLUSIONS

These data provide functional and associative clinical evidence of a novel form of drug resistance that involves interactions between gamma-actin and microtubules.

Alterations in prodynorphin gene expression and dynorphin levels in different brain regions after chronic administration of 14-methoxymetopon and oxycodone-6-oxime

Previous studies showed that opioid drugs-oxycodone-6-oxime and 14-methoxy-5-methyl-dihydromorphinone (14-methoxymetopon)-produced less respiratory depressive effect and slower rate of tolerance and dependence, respectively. It was also reported that morphine decreased the prodynorphin gene expression in the rat hippocampus, striatum and hypothalamus. In this study, we determined the prodynorphin gene expression and dynorphin levels in selected brain regions of opioid tolerant rats. We found that in the striatum morphine decreased, while oxycodone-6-oxime increased and 14-methoxymetopon did not alter the prodynorphin gene expression. In the nucleus accumbens, morphine and oxycodone-6-oxime did not change, while 14-methoxymetopon increased the prodynorphin gene expression. In the hippocampus both oxycodone-6-oxime and 14-methoxymetopon enhanced, whereas morphine did not alter the prodynorphin gene expression. In the rat striatum only oxycodone-6-oxime increased dynorphin levels significantly in accordance with the prodynorphin mRNA changes. In the hippocampus both opioid agonists increased the dynorphin levels significantly similarly to the augmented prodynorphin gene expression. In ventral tegmental area only 14-methoxymetopon increased dynorphin levels significantly. In nucleus accumbens and the temporal-parietal cortex the changes in the prodynorphin gene expression and the dynorphin levels did not correlate. Since the endogenous prodynorphin system may play a modulatory role in the development of opioid tolerance, the elevated supraspinal dynorphin levels appear to be partly responsible for the reduced degree of tolerance induced by the investigated opioids.

Chronic and acute effects of 3,4-methylenedioxy-N-methylamphetamine ('Ecstasy') administration on the dynorphinergic system in the rat brain

The prodynorphin system is implicated in the neurochemical mechanism of psychostimulants. Exposure to different drugs of abuse can induce neuroadaptations in the brain and affect opioid gene expression. The present study aims to examine the possibility of a common neurobiological substrate in drug addiction processes. We studied the effects of single and repeated 3,4-methylenedioxy-N-methylamphetamine ('Ecstasy') on the gene expression of the opioid precursor prodynorphin, and on the levels of peptide dynorphin A in the rat brain. Acute (8 mg/kg, intraperitoneally) 3,4-methylenedioxy-N-methylamphetamine markedly raised, two hours later, prodynorphin mRNA levels in the prefrontal cortex, and in the caudate putamen, whereas it decreased gene expression in the ventral tegmental area. Chronic (8 mg/kg, intraperitoneally, twice a day for 7 days) 3,4-methylenedioxy-N-methylamphetamine increased prodynorphin mRNA in the nucleus accumbens, hypothalamus and caudate putamen and decreased it in the ventral tegmental area. Dynorphin A levels increased after chronic treatment in the ventral tegmental area and decreased after acute treatment in the nucleus accumbens, prefrontal cortex and hypothalamus. These findings confirm the role of the dynorphinergic system in mediating the effects of drugs of abuse, such as 3,4-methylenedioxy-N-methylamphetamine, in various regions of the rat brain, which may be important sites for the opioidergic mechanisms activated by addictive drugs.

Reduced density of cholinergic interneurons in the ventral striatum in schizophrenia: an in situ hybridization study

BACKGROUND

The role of the striatum in the pathophysiology of schizophrenia is not understood. In a previous postmortem study, we found a reduction in the density of striatal interneurons that stain immunohistochemically for choline acetyltransferase (ChAT) in schizophrenia.

METHODS

To determine whether this finding represents a specific alteration in ChAT gene expression, we used in situ hybridization to study the striatum of 11 control and 9 schizophrenic subjects with oligonucleotide probes complementary to human ChAT mRNA, preprosomatostatin (PPS) mRNA, and beta-actin mRNA. Densities of ChAT mRNA-positive neurons, ChAT mRNA expression per neuron, PPS mRNA-positive neurons, and beta-actin mRNA expression levels were measured.

RESULTS

There were no significant differences between the two groups in densities of PPS mRNA-positive neurons and levels of beta-actin mRNA expression throughout the striatum, or in densities of ChAT mRNA-positive neurons in the caudate nucleus or putamen. However, in the ventral striatum, the mean density of ChAT mRNA-positive neurons was reduced to 26% of control levels in the schizophrenic group.

CONCLUSIONS

There is a reduction in number or function of the cholinergic interneurons of the ventral striatum in schizophrenia.

MHC Class I–Associated Peptides Identified From Normal Platelets and From Individuals With Idiopathic Thrombocytopenic Purpura

Major histocompatibility complex (MHC) class I molecules bind and display peptide antigens on the cell surface. CD8(+) T lymphocytes recognize peptides in association with class I proteins to initiate a cytotoxic immune response. To understand the specificity of such immune responses and to facilitate the development of therapies for disease, it is important to identify MHC-presented peptides. In this study, platelets, easily obtainable and often associated with immune-mediated disease, were selected to identify MHC class I-associated peptides. MHC-associated peptides presented on platelets of normal individuals and individuals with idiopathic thrombocytopenic purpura (ITP) were characterized. ITP is characterized by the premature immune destruction of platelets. It is associated with the production of antiplatelet autoantibodies, most often targeting platelet membrane GPIIb/IIIa or GPIb/IX. In addition to characterizing five fully and several partially sequenced peptides from platelets, the peptide GPRGA(L/I)S(L/I)(L/I) was identified from four of the five ITP patients. The anchor motif of this peptide correlates with the presence of the HLA-B7 allele. A BLAST search identified this peptide as GPIb (4-12). In conclusion, platelets from normal and ITP individuals can present peptides from general cellular proteins and platelet specific proteins, such as GPIb, to the immune system via MHC class I.

Regulation of pancreatic somatostatin gene expression by insulin and glucagon

Rainbow trout were used as a model system to study the effects of insulin and glucagon on the expression of preprosomatostatins (PPSS). We previously showed that the endocrine pancreas of trout contains three mRNAs that encode for distinct somatostatin-containing peptides: PPSS I, which contains somatostain-14 (SS-14) at its C-terminus, and two separate PPSS IIs, PPSS II' and PPSS II'', each containing [Tyr7, Gly10]-SS-14 at their C-terminus. Rainbow trout injected (100 ng/g body weight) with insulin displayed elevated expression of PPSS II' and PPSS II'' mRNAs. Glucagon-injected (100 ng/g body weight) animals displayed elevated pancreatic expression of all PPSS mRNAs compared to saline-injected control animals. Insulin directly stimulated the expression of pancreatic PPSS II' and PPSS II'' mRNAs in vitro in a dose-dependent manner in the presence of 4mM glucose. Glucagon, in the presence of 10mM glucose, directly stimulated the expression of all PPSS mRNAs in a dose-dependent manner in vitro. These results indicate that the pancreatic expression of PPSS mRNAs is differentially regulated by insulin and glucagon and that the regulatory pattern is dependent on glucose concentration.

Constitutive activation of transcription factor AP-1 in cervical cancer and suppression of human papillomavirus (HPV) transcription and AP-1 activity in HeLa cells by curcumin

The transcription factor AP-1 plays a central role in the transcriptional regulation of specific types of high-risk human papillomaviruses (HPVs) such as HPV16 and HPV18, which are etiologically associated with the development of cancer of the uterine cervix in women. In our study, we investigated the AP-1 binding activity and the expression pattern of different members of the AP-1 transcription factor family (c-Jun, JunB, JunD, c-Fos, FosB, Fra-1 and Fra-2) in different grades of cervical lesions starting from mild dysplasia to invasive cervical tumors, including normal control tissues, using specific antibodies raised against each of the AP-1 members. Results indicate that though AP-1 showed high binding activity and the majority of its members were highly expressed in tumor tissues, there is a distinct pattern of gradual increase of c-fos and a concomitant decrease of fra-1 expression that perfectly match the progression of cervical lesions. While c-fos is highly expressed in invasive cervical tumor, the expression of fra-1 becomes almost nil or absent, but the reverse is true in both controls and early precancerous lesions. These findings corroborate the results obtained in the cervical cancer cell line, HeLa. Interestingly, despite very low or absent AP-1 binding in normal as well as in premalignant lesions, AP-1 transcription and its binding activity was found to be very high in malignant tissues showing a preferential heterodimerization of c-fos with JunB instead of its canonical dimerization partner c-jun. Both in vivo and in vitro studies demonstrate that the overexpression of c-fos and downregulation of fra-1 expression as well as a change in the dimerization pattern of the AP-1 complex seem to play a crucial role during progression to malignancy. In a previous study, we demonstrated that a synthetic antioxidant, pyrrolidine dithiocarbamate (PDTC) can selectively downregulate HPV expression in human keratinocytes and cervical cancer cell lines. Since a redox regulatory pathway is involved in the expression of HPV that can be modulated by an antioxidant-induced reconstitution of the AP-1 transcription complex, we have used curcumin (diferuloylmethane), an active component of the perennial herb turmeric, which is a potent antioxidant and is well-known for its antiinflammatory and anticarcinogenic activity, to modulate the transcription of AP-1 and HPV. We demonstrate for the first time that curcumin can selectively downregulate HPV18 transcription as well as the AP-1 binding activity in HeLa cells. Most interestingly, curcumin can reverse the expression dynamics of c-fos and fra-1 in this tumorigenic cell line, mimicking the expression pattern observed in normal controls or precancerous lesions. Observation of curcumin-mediated complete downregulation of AP-1 binding activity and reversal of c-fos/fra-1 transcription to a normal state in tumorigenic HeLa cells represents a novel mechanism that can control transcription of pathogenic HPVs during keratinocyte differentiation and progression of cervical cancer. Our study thus provides a basis for developing a novel therapeutic approach to control pathogenic HPV infection by using potent antioxidative agents, such as curcumin.

The hamster androgen receptor promoter: a molecular analysis

The steroid/thyroid hormone receptors are members of a very large family of nuclear-activated transcription factors. These receptors play a crucial role in most biological function, including regulation of development, metabolism, behaviour and reproduction. Among androgen receptor (AR), we have recently demonstrated that its expression in the Harderian gland (HG) of the male hamster is under a well-co-ordinated cross-talk between various steroid hormone receptors. Here, are presented data on the sequence of hamster AR promoter region (5'UTR) and the molecular tools of its regulation. The 5'UTR is 1585 bp. The promoter region shows various responsive elements. Two putative CREM elements are present at -71 and -1576 bp. A putative retinoic acid responsive element is present at -1476 bp. An androgen/glucocorticoid responsive element is present at -473 bp. A putative thyroid hormone-responsive element at -381 bp and an estrogen responsive element at -230 bp. Also, a homopurinic stretch is evident between -1199 and -1118. Furthermore, Sp1 sites are also spread along the sequence. As well as for human, mouse, rat and pig, the hamster lacks the canonical promoter TATA and CCAAT boxes. Gel retardation experiments confirm the presence of active responsive elements for AR, estrogen receptor, glucocorticoid receptor and thyroid hormone receptor. Previous data on the regulation of expression of AR by other members of steroid/thyroid hormone receptors well correlate with sequence analysis and gel retardation experiments. Thus, androgens, thyroid hormone, stimulate the AR transcription, while synthetic glucocorticoid (Dex) and estrogen are potent inhibitors of AR expression. The comparison of hamster AR promoter sequence with other AR promoter shows an 89, 82, 84 and 84% identity with human, rat, mouse and pig AR promoter, respectively. These results, in the light of the extreme plasticity of hamster HG, suggest that the comparative study of expression and regulation of AR gene in the HG of the hamster offers a useful tool to approach the normal and pathological phenotype in human.

Oxidative stress-mediated, post-translational loss of MafA protein as a contributing mechanism to loss of insulin gene expression in glucotoxic beta cells

Glucose toxicity in pancreatic islet beta cells causes loss of insulin gene expression, content, and secretion due to loss of binding of transcription factors, most notably PDX-1 and RIPE-3b1 activator, to the promoter region of the insulin gene. Recently, RIPE-3b1 activator was cloned and identified as the mammalian homologue of avian MafA/Maf-L (MafA). This enabled us to carry out more extensive studies of the role of MafA in glucotoxicity than were hitherto possible. Northern analysis of glucotoxic HIT-T15 cells revealed normal amounts of MafA mRNA, but Western analysis demonstrated a 97 +/- 1% reduction in MafA protein (p < 0.0001). The proteasome is a likely site for MafA degradation as lactacystin, an irreversible proteasome inhibitor, caused an accumulation of MafA protein. Antioxidants have previously been shown to prevent the adverse effects of glucose toxicity on beta cell function both in vivo and in vitro. In the current study, chronic culturing of HIT-T15 cells with the antioxidant N-acetylcysteine (NAC) prevented loss of MafA protein (late passage = 18.9 +/- 10.4% of early passage, p < 0.001; late passage with NAC = 68.7 +/- 19.7% of early passage, p = not significant) and loss of DNA binding (late passage = 63.7 +/- 9% of early passage, p < 0.02; late passage with NAC = 116 +/- 10% of early passage, p = not significant). Additionally, transient transfection of PDX-1 or MafA cDNA into glucotoxic cells increased PDX-1 and MafA protein levels and individually increased insulin promoter activity (untreated = 34%, PDX-1 = 70%, MafA = 78%; percentage of activity of early passage cells), whereas the combined transfection of MafA and PDX-1 completely restored insulin promoter activity. This recovery of promoter activity following transient transfection had no effect on endogenous insulin mRNA. However, adenoviral infection of MafA and PDX-1 significantly increased endogenous insulin mRNA levels by 93% (121 +/- 9 versus 233 +/- 18 density light units; n = 5, p < 0.001). We conclude that the absence of MafA protein from beta cells via chronic oxidative stress contributes importantly to the loss of endogenous insulin gene expression as glucose toxicity develops.

Molecular cloning and sequence analysis of cDNAs encoding for Boophilus microplus, Haemaphysalis longicornis and Rhipicephalus appendiculatus actins

The nucleotide and deduced amino acid sequences of the actins from ticks, Boophilus microplus, Haemaphysalis longicornis and Rhipicephalus appendiculatus, have been determined. Nucleotide sequence analysis showed open reading frames of 1128-nucleotide-long encoding proteins of 376 amino acids with a predicted molecular weight of 41.82 kDa each. Comparison between the nucleic acid and deduced amino acid sequences as well as structural and phylogenetic analyses of these genes confirmed the high similarity among actins from ticks in comparison to other species.

Effects of the selective norepinephrine uptake inhibitor nisoxetine on prodynorphin gene expression in rat CNS

Cocaine binds to dopamine (DA), serotonin (5-HT) and norepinephrine (NE) transporters blocking the reuptake of these monoamines into presynaptic terminals. As previously reported, continuous infusion of cocaine for seven days or GBR 12909, a selective dopamine uptake inhibitor, produced significant decreases in prodynorphin (PDYN) gene expression in the hypothalamus. Cocaine also produced a significant increase in PDYN mRNA in the caudate putamen, whereas GBR12909 has no effect and the selective serotonin uptake inhibitor fluoxetine decreases PDYN mRNA in the same brain region. The effect of the selective norepinephrine uptake inhibitor nisoxetine was examined on PDYN gene expression. Nisoxetine or vehicle was infused continuously for 7 days via osmotic minipump into male rats. This treatment produced significant increases in PDYN gene expression in the hypothalamus (183% of control), nucleus accumbens (142% of control) and hippocampus (124% of control) and a significant decrease in the caudate putamen (69% of control). These data suggest that nisoxetine affects PDYN gene expression and support a role for NE in the mechanisms underlying the effects of chronic exposure to psychoactive drugs. Moreover, nisoxetine, as well as fluoxetine, decreases PDYN mRNA in the caudate putamen, in contrast to the up-regulation produced by cocaine. Thus, the inhibition of NE uptake alone cannot account for the cocaine-induced increase of PDYN gene expression. These findings suggest that PDYN gene expression regulation by cocaine in the caudate putamen might be due to a combination of effects on two or three monoamine transporters, or to a mechanism unrelated to transporters inhibition.

Insufficient folding of type IV collagen and formation of abnormal basement membrane-like structure in embryoid bodies derived from Hsp47-null embryonic stem cells

Hsp47 is a molecular chaperone that specifically recognizes procollagen in the endoplasmic reticulum. Hsp47-null mouse embryos produce immature type I collagen and form discontinuous basement membranes. We established Hsp47-/- embryonic stem cell lines and examined formation of basement membrane and production of type IV collagen in embryoid bodies, a model for postimplantation egg-cylinder stage embryos. The visceral endodermal cell layers surrounding Hsp47-/- embryoid bodies were often disorganized, a result that suggested abnormal function of the basement membrane under the visceral endoderm. Rate of type IV collagen secretion by Hsp47-/- cells was fourfold lower than that of Hsp47+/+ cells. Furthermore, type IV collagen secreted from Hsp47-/- cells was much more sensitive to protease digestion than was type IV collagen secreted from Hsp47+/+ cells, which suggested insufficient or incorrect triple helix formation in type IV collagen in the absence of Hsp47. These results indicate for the first time that Hsp47 is required for the molecular maturation of type IV collagen and suggest that misfolded type IV collagen causes abnormal morphology of embryoid bodies.

Colcemid resistance in murine SEWA cells: non-Pgy gene amplification at low levels of resistance and preferential Pgy2 gene amplification at high levels of resistance

Mammalian cell lines often become multidrug-resistant to cytotoxic drugs by amplification and/or overexpression of the P-glycoprotein (Pgy) genes. However, several malignant cell lines seem to acquire low levels of drug resistance by non-P-glycoprotein mediated mechanisms. We report here on cytogenetical signs of non-Pgy gene amplification in murine SEWA cells during the early steps of selection in Colcemid (COL). In line TC13COL0.01, rare cells exhibited a homogeneously staining region (HSR) distally in chromosome 16. As the COL-concentration was raised the HSR-chromosome was retained and, in addition, the cells developed numerous double minutes (DMs). The DMs, but not the HSR, contained amplified Pgy genes. The HSR may correspond to amplified heat shock protein 70 (Hsp70) genes, detected by Southern analysis. A second low-level COL-resistant line, TC13D70.01, contained DMs but showed no amplification of Pgy, Hsp70, Hsp90, alpha- or beta-tubulin genes. In higher COL-concentration, P-glycoprotein mediated drug resistance was induced. In contrast to actinomycin D-resistant SEWA cells, in which higher amplification levels of Pgy1 than of Pgy2 are regularly present, the COL-resistant lines showed a preference for Pgy2 gene amplification. These results are in line with the suggestion that the murine Pgy1 and Pgy2 genes have overlapping but distinct drug specificities.

Inhibition of cyclosporin A-induced gingival overgrowth by azithromycin through phagocytosis: an in vivo and in vitro study

BACKGROUND

The objective of the present study was to investigate the effect of cyclosporin A (CsA) and azithromycin (AZI) on collagen metabolism in the gingiva of rats.

METHODS

Fifty 6-week-old male Sprague-Dawley (SD) rats (weight 120 to 150 g) were randomly distributed into five groups. All groups received various drugs via gastric feeding for 7 weeks. The first group (Mo group) received mineral oil for 7 weeks as a control; the CsA group received CsA in mineral oil for 7 weeks (dosage 30 mg/kg); the CsA/Mo group received CsA in mineral oil for 6 weeks and mineral oil only for the seventh week; the CsA/AZI group received CsA in mineral oil for 6 weeks and AZI (dosage 10 mg/kg) in mineral oil simultaneously with CsA in the seventh week; and the Mo/AZI group received mineral oil for 6 weeks and AZI in mineral oil for the seventh week. All animals were sacrificed for clinical and histological analyses. Gingival fibroblasts were cultured at the fourth passage, and the amount of collagen was measured. Type I collagen and collagenase mRNA were measured by reverse transcription-polymerase chain reaction. Collagen phagocytosis assay also was performed.

RESULTS

Clinically, CsA induced gingival overgrowth in rats, whereas AZI reduced gingival overgrowth. Histological results of the CsA group showed a marked increase of tissue volume compared to the other groups. High collagen amounts were found when gingival overgrowth was induced. However, type I collagen mRNA and collagenase mRNA expressions did not statistically differ among groups. Phagocytosis assay showed that CsA decreased phagocytic activity of gingival fibroblasts, whereas AZI increased the activity. These results suggest that the induction and reduction of CsA-induced gingival overgrowth were closely associated with phagocytic activity.

CONCLUSION

Cyclosporin A decreases collagen degradation by lowering phagocytic activity of rat gingival fibroblasts. Azithromycin partially compensates for this lowered phagocytic activity.

Growth hormone and insulin-like growth factor-1 differentially stimulate the expression of preprosomatostatin mRNAs in the Brockmann bodies of rainbow trout, Oncorhynchus mykiss

We previously characterized three cDNAs obtained from the endocrine pancreas (Brockmann body) of rainbow trout that encode for distinct preprosomatostatin (PPSS) molecules: PPSS I containing somatostain-14 (SS-14) at its C-terminus and two separate PPSS IIs, PPSS II' and PPSS II'', containing [Tyr7,Gly10]-SS-14 at their C-termini. In this study, we examined the control of PPSS I, PPSS II', and PPSS II'' mRNA expression by growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Rainbow trout implanted with GH for 21 days displayed elevated pancreatic expression of all PPSS mRNAs compared to control animals. Growth hormone directly stimulated the expression of all pancreatic PPSS mRNAs in vitro in a dose-dependent manner; however, GH was a more potent stimulator of PPSS II' expression than of PPSS I or PPSS II'' expression. Insulin-like growth factor-1 also directly stimulated the expression of PPSS mRNAs in a dose-dependent manner in Brockmann bodies incubated in vitro; IGF-1 was a more potent stimulator of PPSS I and PPSS II' expression than of PPSS II'' expression. These results indicate that the expression of PPSS mRNAs in the Brockmann body of trout is differentially regulated by GH and IGF-1 and suggest that SS mediate the feedback regulation of GH and IGF-1.

The interferon regulatory factor ICSBP/IRF-8 in combination with PU.1 up-regulates expression of tumor suppressor p15(Ink4b) in murine myeloid cells

CDKN2B (INK4B), which encodes the cyclin-dependent kinase inhibitor p15(INK4b), is up-regulated by many cytokines found in hematopoietic environments in vivo. In human acute myeloid leukemias (AMLs), it is inactivated with high frequency. To gain insight into the regulatory pathways leading to the normal activation of p15(Ink4b) expression, we examined interferon beta (IFNbeta)-induced transcription. Using reporter gene assays in murine myeloid cells M1, we determined that a 328-bp fragment, located 117 to 443 bp upstream of the translation initiation site, was sufficient to activate transcription. Both the interferon consensus sequence-binding protein/interferon regulatory factor 8 (ICSBP/IRF-8) and PU.1 were able to increase transcription from this region. It was determined that both ICSBP and PU.1 must bind to DNA to form a stable PU.1/ICSBP binding complex. Interestingly, introduction of the ICSBP into ICSBP-null Tot2 cells led to a significant increase in p15(Ink4b) RNA expression. This regulation of the Ink4b promoter is apparently myeloid specific because both ICSBP and PU.1 are myeloid commitment factors. Importantly, this provides a mechanism to explain in part the tumor suppressor activity of ICSBP, since ICSBP-deficient mice develop a chronic myelogenous leukemia (CML)-like disease and a high percentage of human AML and CML lack ICSBP transcripts.

The primate embryo gene expression resource: a novel resource to facilitate rapid analysis of gene expression patterns in non-human primate oocytes and preimplantation stage embryos

Detailed molecular studies of preimplantation stage development in a suitable nonhuman primate model organism have been inhibited due to the cost and scarcity of embryos. To circumvent these limitations, we have created a new resource for the research community, designated as the Primate Embryo Gene Expression Resource (PREGER). The PREGER sample collection currently contains over 160 informative samples of oocytes, obtained from various sized antral follicles, and embryos obtained through a variety of different protocols. The PREGER makes it possible to undertake quantitative gene-expression studies in rhesus monkey oocytes and embryos through simple and cost-effective hybridization-based methods. The PREGER also makes available other molecular tools to facilitate nonhuman primate embryology. We used PREGER here to compare the temporal expression patterns of five housekeeping mRNAs and three transcription factor mRNAs between mouse and rhesus monkey. We observed noticeable differences in temporal expression patterns between species for some mRNAs, but clear similarities for others. Our results also provide new information related to genome activation and the effects of embryo culture conditions on gene expression in primate embryos. These results provide one illustration of how the PREGER can be employed to obtain novel insight into primate embryogenesis.

Tyrphostin AG 555 inhibits bovine papillomavirus transcription by changing the ratio between E2 transactivator/repressor function

The tyrosine kinase inhibitor (tyrphostin) AG 555 selectively interferes with viral transcription in bovine papillomavirus type 1 (BPV-1)-transformed fibroblasts and induces suppression of cyclin-dependent kinase activity and cell cycle arrest. Concomitant with inhibition of viral transcription, c-Jun was strongly up-regulated, which was consistent with the observation that AG 555 treatment also led to an activation of the mitogen-activated protein kinase pathway by enhancing phosphorylation of JNK and p38. Increased JNK and p38 activity resulted in higher phosphorylation of the AP-1 family members c-Jun and activating transcription factor 2. Scanning the BPV-1 genome for potential binding sequences, an intragenic AP-1 site (BAP-1) within the E7 open reading frame was detected. Enhanced dimerization of phosphorylated activating transcription factor 2 together with c-Jun and binding to BAP-1 seem to be responsible for viral dysregulation because both suppression of BPV-1 and induction of c-Jun mRNA could be almost entirely abrogated by simultaneous treatment with SB 203580, an inhibitor of p38 mitogen-activated protein kinase activity. Moreover, dissecting the complex transcriptional pattern of episomal BPV-1 with specific primer sets for reverse transcription-PCR analysis, the repressive effect could be attributed to a selective down-regulation of the mRNA encoding the E2 transactivator function in favor of the E2 repressor, whose mRNA level remained constant during AG 555 treatment. These data indicate that tyrphostin AG 555 disturbs the balance of negative and positive regulatory factors necessary to maintain the homeostasis of a virus-transformed phenotype.

Increased messenger RNA for allograft inflammatory factor-1, LERK-5, and a novel gene in 17.5-day relative to 15.5-day bovine embryos

Considerable embryonic loss occurs between Gestation Days 15 and 18 in cattle when critical cellular and molecular events occur, including maternal recognition of pregnancy. To gain insight into these events, mRNA differential display analysis was used to identify eight unique cDNA fragments present in greater abundance in 17.5-day than in 15.5-day bovine embryos. Four cDNA fragments, confirmed to be upregulated in 17.5-day embryos using Northern analysis, were cloned and sequenced. Three cDNA fragments shared sequence identities with known homologs: human allograft inflammatory factor-1 (AIF-1), human LERK-5, and bovine interferon-tau. One novel cDNA fragment did not share sequence identity to previously reported genes, except for a similar DNA sequence in the human genome. AIF-1 mRNA was present in developing placenta through Gestation Day 36, and abundant levels were observed in adult bovine spleen and lung. The novel gene, which we have named periattachment factor (PAF), was not detected in adult tissues using Northern analysis or in conceptuses between Days 30 and 36 of pregnancy. Additional sequence information for bPAF was obtained from a cDNA library constructed from a 25-day bovine embryo. The protein corresponding to the open reading frame has four protein kinase C phosphorylation sites, two casein kinase II phosphorylation sites, a nuclear targeting sequence, but no obvious DNA or RNA binding motifs. Abundant expression of this gene during a narrow but critical window of embryonic development makes it worthy of further study.

Heat-shock protein 70 favours human liver recovery from ischaemia-reperfusion

BACKGROUND

Pringle's manoeuvre controls excessive bleeding, but results in ischaemia-reperfusion injury during liver surgery. Activation of the heat-shock protein system of cell defense has been demonstrated after ischaemia-reperfusion injury in animal tissues. The aim of the present study was to determine whether the ischaemia-reperfusion accompanying hepatic surgery induces heat-shock protein 70 (HSP70) in human liver and whether the induction of HSP70 is related to the recovery of liver function.

METHODS

Heat-shock protein 70 and gamma-actin mRNAs were assayed in the liver biopsies of 10 subjects undergoing partial hepatectomy for localized lesions. Measurements were performed before the Pringle's manoeuvre and at the end of the surgery. Transaminases and fibrinogen were measured before and at 12, 24 and 36 h following hepatectomy.

RESULTS

After an average 40 +/- 8-min period of warm ischaemia, a significant increase of HSP70 mRNA (187 +/- 67%, 2P < 0.05) was observed. The acute increase of HSP70 mRNA correlates with the decrease of transaminases (AST: rs -0.964, ALT: rs -0.891, P < 0.002) and the increase of fibrinogen (rs -0.7, P < 0.02) observed between 12 and 24 h following surgery.

CONCLUSIONS

Heat-shock protein 70 is induced by ischaemia-reperfusion injury in human liver. Its induction seems to have beneficial effects, including a prompt reduction of transaminases and a rapid recovery of fibrinogen synthesis.

Expression of the mouse gonadotropin-releasing hormone receptor gene in alpha T3-1 gonadotrope cells is stimulated by cyclic 3',5'-adenosine monophosphate and protein kinase A, and is modulated by Steroidogenic factor-1 and Nur77

Regulation of GnRH receptor (GnRHR) expression levels in the pituitary is a crucial control point in reproduction. The promoter of the mouse GnRHR gene contains nuclear receptor half-sites (NRS) at -244/-236 and -15/-7 relative to the translation start site. Although binding of steroidogenic factor-1 (SF-1) to the -244/-236NRS is implicated in mediating basal and gonadotrope-specific expression, no function or protein-DNA interactions have previously been described for the -15/-7NRS. We report that levels of the endogenous GnRHR mRNA in alpha T3-1 cells are stimulated by forskolin and 8-bromo-cAMP. We also show that the orphan nuclear receptor Nur77 is expressed in alpha T3-1 cells, and that both SF-1 and Nur77 bind to the -15/-7NRS and -244/-236NRS in vitro. We show that the activity of the proximal (-579/+1) mouse GnRHR promoter is up-regulated by protein kinase A, via a mechanism that is modulated by SF-1, both positively and negatively, through binding to the -244/-236NRS or the -15/-7NRS, respectively. Nur77 appears to be capable of acting as a negative regulator of this response, via the -15/-7NRS. Furthermore, we show that forskolin up-regulates SF-1 mRNA levels in alpha T3-1 cells, indicating that the levels of SF-1 play a role in modulating the protein kinase A response.

Impaired expression of peroxisome proliferator-activated receptor gamma in ulcerative colitis

BACKGROUND & AIMS

The peroxisome proliferator-activated receptor gamma (PPAR gamma) has been proposed as a key inhibitor of colitis through attenuation of nuclear factor kappa B (NF-kappa B) activity. In inflammatory bowel disease, activators of NF-kappa B, including the bacterial receptor toll-like receptor (TLR)4, are elevated. We aimed to determine the role of bacteria and their signaling effects on PPAR gamma regulation during inflammatory bowel disease (IBD).

METHODS

TLR4-transfected Caco-2 cells, germ-free mice, and mice devoid of functional TLR4 (Lps(d)/Lps(d) mice) were assessed for their expression of PPAR gamma in colonic tissues in the presence or absence of bacteria. This nuclear receptor expression and the polymorphisms of gene also were assessed in patients with Crohn's disease (CD) and ulcerative colitis (UC), 2 inflammatory bowel diseases resulting from an abnormal immune response to bacterial antigens.

RESULTS

TLR4-transfected Caco-2 cells showed that the TLR4 signaling pathway elevated PPAR gamma expression and a PPAR gamma-dependent reporter in an I kappa kappa beta dependent fashion. Murine and human intestinal flora induced PPAR gamma expression in colonic epithelial cells of control mice. PPAR gamma expression was significantly higher in the colon of control compared with Lps(d)/Lps(d) mice. Although PPAR gamma levels appeared normal in patients with CD and controls, UC patients displayed a reduced expression of PPAR gamma confined to colonic epithelial cells, without any mutation in the PPAR gamma gene.

CONCLUSIONS

These data showed that the commensal intestinal flora affects the expression of PPAR gamma and that PPAR gamma expression is considerably impaired in patients with UC.

Oxathiolene oxides: a novel family of compounds that induce ferritin, glutathione S-transferase, and other proteins of the phase II response

Compounds that induce the synthesis of cytoprotective phase II enzymes have shown promise as cancer chemopreventive agents. Although chemically diverse, phase II enzyme inducers are capable of participating in Michael reaction chemistry. We have synthesized a novel class of organosulfur compounds, termed oxathiolene oxides (OTEOs). Based on their chemical properties, we hypothesized that these compounds could function as phase II enzyme inducers. Northern blot analysis showed that oxathiolene oxides induce the phase II enzymes glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1 (NQO1), and ferritin H and L mRNA in a concentration-dependent fashion in a normal embryonic mouse liver cell line, BNLCL.2. OTEO-562 (3-cyclohexenyl-4-methyl-1,2-oxathiol-3-ene-2-oxide) was the strongest inducer. Western blot analysis demonstrated that GST-alpha and ferritin H protein levels were also induced in cells treated with OTEO-562, as was total GST and NQO1 enzyme activity. Further, induction of NQO1 activity by OTEO-562 was equivalent in aromatic hydrocarbon (Ah) receptor wild-type and Ah receptor mutant cell lines, suggesting that oxathiolene oxides activate phase II enzymes by an Ah receptor-independent mechanism. Consistent with this observation, OTEO-562 failed to induce cytochrome P450 1A1 mRNA. These results suggest that oxathiolene oxides may merit further investigation as candidate chemopreventive agents.

Molecular genetics of 3beta-hydroxy-Delta5-C27-steroid oxidoreductase deficiency in 16 patients with loss of bile acid synthesis and liver disease

The 3beta-hydroxy-Delta(5)-C(27)-steroid oxidoreductase (C(27) 3beta-HSD) is a membrane-bound enzyme of the endoplasmic reticulum that catalyzes an early step in the synthesis of bile acids from cholesterol. Subjects with autosomal recessive mutations in the encoding gene, HSD3B7, on chromosome 16p11.2-12 fail to synthesize bile acids and develop a form of progressive liver disease characterized by cholestatic jaundice and malabsorption of lipids and lipid-soluble vitamins from the gastrointestinal tract. The gene encoding the human C(27) 3beta-HSD enzyme was isolated previously, and a 2-bp deletion in exon 6 of HSD3B7 was identified in a well characterized subject with this disorder. Here, we report a molecular analysis of 15 additional patients from 13 kindreds with C(27) 3beta-HSD deficiency. Twelve different mutations were identified in the HSD3B7 gene on chromosome 16p11.2-12. Ten mutations were studied in detail and shown to cause complete loss of enzyme activity and, in two cases, alterations in the size or amount of the transcribed mRNA. Mutations were inherited in homozygous form in 13 subjects from 10 families and compound heterozygous form in four subjects from three families. We conclude that a diverse spectrum of mutations in the HSD3B7 gene underlies this rare form of neonatal cholestasis.

Growth arrest of HPV-positive cells after histone deacetylase inhibition is independent of E6/E7 oncogene expression

Inhibitors of histone deacetylase (HDAC) are capable of arresting growth in cervical carcinoma cells in the G1 phase of the cell cycle. Although HPV E6/E7 mRNA steady-state levels appeared to be constant after prolonged treatment, time-course experiments revealed that viral transcription was transiently down-regulated between 7-10 h prior to cdk2 suppression. To test whether transitory suppression was a prerequisite for the biological outcome after HDAC inhibition, we took advantage of two immortalized human keratinocyte cell lines in which E6/E7 oncogene expression was controlled by different regulatory regions. After treatment with sodium butyrate (NaB) or trichostatin A (TSA), HPV16 upstream regulatory region (URR)-directed transcription was down-regulated, showing kinetics similar to those in cervical carcinoma cells. In contrast, beta-actin promoter controlled E6/E7 transcription was even temporarily increased and finally declined to levels initially detected in the untreated controls. Both cell lines, however, were arrested in G1 and showed complete suppression of cdk2 activity that was preceded by a strong up-regulation of the cdk2 inhibitors p21(CIP1) and p27(KIP1). These results demonstrate that growth of HPV16/18-positive cells can be arrested by HDAC inhibitors despite ongoing HPV transcription and thus independently of any potential position effects uncoupling URR-directed gene expression by adjacent cellular promoters or by downstream 3'-polyadenylation sites after viral integration into the host genome during multistep carcinogenesis.

Involvement of the neuropeptide nociceptin/orphanin FQ in kainate seizures

The neuropeptide nociceptin/orphanin FQ (N/OFQ) has been shown to modulate neuronal excitability and neurotransmitter release. Previous studies indicate that the mRNA levels for the N/OFQ precursor (proN/OFQ) are increased after seizures. However, it is unclear whether N/OFQ plays a role in seizure expression. Therefore, (1) we analyzed proN/OFQ mRNA levels and NOP (the N/OFQ receptor) mRNA levels and receptor density in the kainate model of epilepsy, using Northern blot analysis, in situ hybridization, and receptor binding assay, and (2) we examined susceptibility to kainate seizure in mice treated with 1-[(3R, 4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1, 3-dihydro-benzimidazol-2-one (J-113397), a selective NOP receptor antagonist, and in proN/OFQ knock-out mice. After kainate administration, increased proN/OFQ gene expression was observed in the reticular nucleus of the thalamus and in the medial nucleus of the amygdala. In contrast, NOP mRNA levels and receptor density decreased in the amygdala, hippocampus, thalamus, and cortex. Mice treated with the NOP receptor antagonist J-113397 displayed reduced susceptibility to kainate-induced seizures (i.e., significant reduction of behavioral seizure scores). N/OFQ knock-out mice were less susceptible to kainate seizures compared with their wild-type littermates, in that lethality was reduced, latency to generalized seizure onset was prolonged, and behavioral seizure scores decreased. Intracerebroventricular administration of N/OFQ prevented reduced susceptibility to kainate seizures in N/OFQ knock-out mice. These data indicate that acute limbic seizures are associated with increased N/OFQ release in selected areas, causing downregulation of NOP receptors and activation of N/OFQ biosynthesis, and support the notion that the N/OFQ-NOP system plays a facilitatory role in kainate seizure expression.

Differential regulation of gonadotropin-releasing hormone secretion and gene expression by androgen: membrane versus nuclear receptor activation

Steroid hormones induce rapid membrane receptor-mediated effects that appear to be separate from long-term genomic events. The membrane receptor-mediated effects of androgens on GT1-7 GnRH-secreting neurons were examined. We observed androgen binding activity with a cell-impermeable BSA-conjugated testosterone [testosterone 3-(O-carboxymethyl)oxime (T-3-BSA)] and were able to detect a 110-kDa protein recognized by the androgen receptor (AR) monoclonal MA1-150 antibody in the plasma membrane fraction of the GT1-7 cells by Western analysis. Further, a transfected green fluorescent protein-tagged AR translocates and colocalizes to the plasma membrane of the GT1-7 neuron. Treatment with 10 nM 5alpha-dihydrotestosterone (DHT) inhibits forskolin-stimulated accumulation of cAMP, through a pertussis toxin-sensitive G protein, but has no effect on basal cAMP levels. The inhibition of forskolin-stimulated cAMP accumulation by DHT was blocked by hydroxyflutamide, a specific inhibitor of the nuclear AR. DHT, testosterone (T), and T-3-BSA, all caused significant elevations in intracellular calcium concentrations ([Ca(2+)](i)). T-3-BSA stimulates GnRH secretion 2-fold in the GT1-7 neuron, as did DHT or T. Interestingly GnRH mRNA levels were down-regulated by DHT and T as has been reported, but not by treatment with T-3-BSA or testosterone 17beta-hemisuccinate BSA. These studies indicate that androgen can differentially regulate GnRH secretion and gene expression through specific membrane-mediated or nuclear mechanisms.

Androgen inactivation in human lung fibroblasts: variations in levels of 17 beta-hydroxysteroid dehydrogenase type 2 and 5 alpha-reductase activity compatible with androgen inactivation

Androgens delay lung maturation through their action on lung fibroblasts. Knowing that testosterone is secreted by the lung epithelial-like cell line A-549, we have studied the metabolism of androgens by several human lung diploid fibroblasts cell lines. No 17-ketosteroid reductase activity was detected. In contrast, testosterone was transformed mainly into androstenedione and androstanedione with no 5 alpha-dihydrotestosterone formed, indicating the presence of 17 beta- hydroxysteroid dehydrogenase (HSD) type 2 and 5 alpha-reductase activities. The eight cell lines analyzed had either a low or high 17 beta-HSD type 2 activity level. No correlation between these levels and the sex or age stage of cells was established, but Northern blot analysis of human lung RNA samples of five adult subjects revealed very similar variations between subjects in the level of 17 beta-HSD type 2 mRNA. The 5 alpha-reductase activity had a marked substrate preference for androstenedione, the product of 17 beta-HSD type 2. When tritiated testosterone was used as substrate, only barely detectable levels of 5 alpha-dihydrotestosterone were observed by HPLC in the presence of the 17 beta-HSD type 2 inhibitor EM-919. The use of unlabeled testosterone or of the antiandrogen hydroxyflutamide demonstrated that the tritiated testosterone substrate itself had no effect on levels of 5 alpha-reduction. In fact, in these cells, 5 alpha-reductase has no significant activity on testosterone, but it further converts the product of 17 beta-HSD type 2, thus playing a role with 17 beta-HSD type 2 in androgen inactivation. Because androgens delay lung maturation and surfactant synthesis by their action on lung fibroblasts, it is of particular interest to find that the steroid metabolism of these lung fibroblast cells is oriented toward androgen inactivation. Because lung fibroblasts of subjects with low 17 beta-HSD type 2 expression levels are likely to be exposed to higher levels of androgens, an allelic variation of the 17 beta-HSD-2 gene is suspected, which would result in familial incidence of respiratory distress. This is in line with reported cases of familial incidence of respiratory distress.

Involvement of cAMP-response element binding protein in corticotropin-releasing factor (CRF)-induced down-regulation of CRF receptor 1 gene expression in rat anterior pituitary cells

Corticotropin-releasing factor (CRF) is a major secretagogue of adrenocorticotopic hormone from the anterior pituitary and a key activator of the hypothalamic-pituitary-adrenal axis. We previously reported that CRF down-regulates expression of the CRF type-1 receptor (CRF-R1) mRNA in cultured rat anterior pituitary cells. The present study was conducted to clarify the signal transduction systems involved in CRF-induced down-regulation of CRF-R1 gene expression in the anterior pituitary. Northern blot analysis revealed that, under serum-free conditions, 10 nM CRF decreased CRF-R1 mRNA levels in cultured rat anterior pituitary cells as we reported previously. Treatment with 5 mM 8-Br-cAMP reduced CRF-R1 mRNA levels within 2 h. The mRNA level fell to 37+/-3% of the basal level at 2 h and remained low for 16 h after treatment. This CRF-induced reduction of CRF-R1 mRNA expression was inhibited completely by pretreatment with protein kinase A (PKA) inhibitor (1 microM H-89). Further examination revealed that after pretreatment with 10 microM of antisense oligodeoxynucleotide for cyclic AMP-response element binding protein (CREB), the CRF-induced inhibition of CRF-R1 mRNA was partially decreased to 79+/-4% of the control level 2 h after administration of CRF. These findings indicate that CRF may down-regulate CRF-R1 mRNA expression via a cAMP-PKA-mediated mechanism in rat anterior pituitary cells, and that CREB may mediate at least a portion of this inhibitory effect.