Controlled expression of an rpoS antisense RNA can inhibit RpoS function in Escherichia coli

We show that an inducible rpoS antisense RNA complementary to the rpoS message can inhibit expression of RpoS in both exponential and stationary phases and can attenuate expression of the rpoS regulon in Escherichia coli. Plasmids containing rpoS antisense DNA expressed under the control of the T7lac promoter and T7 RNA polymerase were constructed, and expression of the rpoS antisense RNA was optimized in the pET expression system. rpoS antisense RNA levels could be manipulated to effectively control the expression of RpoS and RpoS-dependent genes. RpoS expression was inhibited by the expression of rpoS antisense RNA in both exponential and stationary phases in E. coli. RpoS-dependent catalase HPII was also downregulated, as determined by catalase activity assays and with native polyacrylamide gels stained for catalase. Induced RpoS antisense expression also reduced the level of RpoS-dependent glycogen synthesis. These results demonstrate that controlled expression of antisense RNA can be used to attenuate expression of a regulator required for the expression of host adaptation functions and may offer a basis for designing effective antimicrobial agents.

Neurochemical and behavioral alterations in glucocorticoid receptor-impaired transgenic mice after chronic mild stress

Mice (GR-i) bearing a transgene encoding a glucocorticoid receptor (GR) antisense RNA under the control of a neuron-specific neurofilament promoter were used to investigate the effects of a 4 week chronic mild stress (CMS) on the hypothalamo-pituitary-adrenocortical (HPA) axis and the serotoninergic system in a transgenic model of vulnerability to affective disorders. GR-i mice showed a decrease in both GR-specific binding (hippocampus and cerebral cortex) and GR mRNA levels [hippocampus, cerebral cortex, and dorsal raphe nucleus (DRN)] as well as a deficit in HPA axis feedback control (dexamethasone test) compared with paired wild-type (WT) mice. In the latter animals, CMS exposure caused a significant decrease in both GR mRNA levels and the density of cytosolic GR binding sites in the hippocampus, whereas, in the DRN, GR mRNA levels tended to increase. In contrast, in stressed GR-i mice, both GR mRNA levels and the density of GR binding sites were significantly increased in the hippocampus, cerebral cortex, and DRN. Electrophysiological recordings in brainstem slices and [gamma-35S]GTP-S binding measurements to assess 5-HT1A receptor functioning showed that CMS exposure produced a desensitization of DRN 5-HT1A autoreceptors in WT, but not in GR-i, mice. In addition, CMS was found to facilitate choice behavior of WT, but not GR-i, mice in a decision-making task derived from an alternation paradigm. These results demonstrate that impaired GR functioning affects normal adaptive responses of the HPA axis and 5-HT system to CMS and alters stress-related consequences on decision-making behaviors.

Targeting the type 1 insulin-like growth factor receptor as anti-cancer treatment

The type 1 insulin-like growth factor receptor (IGF1R) is overexpressed by many tumors, and mediates growth, motility and protection from apoptosis. Inhibition of IGF1R expression or function has been shown to block tumor growth and metastasis, and enhance sensitivity to cytotoxic drugs and irradiation. Thus the IGF1R is a highly promising anti-cancer treatment target. This review describes approaches to target the IGF1R using antibodies, small molecule inhibitors of the IGF1R tyrosine kinase, and molecular agents such as antisense and small interfering RNAs. Problems for the clinical introduction of this approach may include toxicity due to normal tissue IGF1R expression and cross-reactivity with the insulin receptor. The next few years will see clinical trials of IGF1R targeting, which offers genuine potential to inhibit tumor growth and chemoresistance in patients with cancer.

Development of an integrative vector for the expression of antisense RNA in Clostridium difficile

A method was developed to use the conjugative transposon Tn916 as a vector for introducing recombinant DNA into Clostridium difficile. This was used to introduce antisense RNA for the adhesin encoding gene cwp66 into C. difficile 79-685. RT-PCR demonstrated that cwp66 specific antisense RNA was produced. However, there was no statistically significant difference in the protein expression or in the adherence of recombinant C. difficile strains. This may be due to the amount of transcripts of the wild-type (sense) cwp66 outnumbering the antisense transcripts or secondary structures present within the cwp66 mRNA. Unlike in other strains of C. difficile, where Tn916 inserts into the genome at highly preferred sites, in C. difficile 79-685, it integrates into multiple sites opening up the possibility of using Tn916 as a mutagen in this strain.

Modulation of the cellulose content of tuber cell walls by antisense expression of different potato (Solanum tuberosum L.) CesA clones

Four potato cellulose synthase (CesA) homologs (StCesA1, 2, 3 and 4) were isolated by screening a cDNA library made from developing tubers. Based on sequence comparisons and the fact that all four potato cDNAs were isolated from this single cDNA-library, all four StCesA clones are likely to play a role in primary cell wall biosynthesis. Several constructs were generated to modulate cellulose levels in potato plants in which the granule-bound starch synthase promoter was used to target the modification to the tubers. The StCesA3 was used for up- and down-regulation of the cellulose levels by sense (SE-StCesA3) and antisense (AS-StCesA3) expression of the complete cDNA. Additionally, the class-specific regions (CSR) of all four potato cellulose synthase genes were used for specific down-regulation (antisense) of the corresponding CesA genes (csr1, 2, 3 and 4). None of the transformants showed an overt developmental phenotype. Sections of tubers were screened for altered cell wall structure by Fourier Transform Infrared microspectroscopy (FTIR) and exploratory Principal Component Analysis (PCA), and those plants discriminating from WT plants were analysed for cellulose content and monosaccharide composition. Several transgenic lines were obtained with mainly decreased levels of cellulose. These results show that the cellulose content in potato tubers can be reduced down to 40% of the WT level without affecting normal plant development, and that constructs based on the CSR alone are specific and sufficient to down-regulate cellulose biosynthesis.

Expression of XIST sense and antisense in bovine fetal organs and cell cultures

Untranslated RNAs transcribed from sense and antisense strands of a gene referred to as X-inactive specific transcript (XIST) play crucial roles in the genetic inactivation and condensation of one of the two X chromosomes in the somatic cells of female mammals. X inactivation is also thought to occur in mammalian male germ cells mainly based on the formation of a condensed structure referred to as a sex body or XY-body, during spermatogenesis. Molecular identity of the sex body, the roles of sense and antisense XIST RNAs in its formation, and the relevance of the sex body to spermatogenesis are not known. Here we report the results of our strand-specific RT-PCR approach to identify the amplicon detected in fetal bovine testes previously referred to as XIST and to test for sense/antisense expression in male and female organs and cell cultures of different sex chromosome constitution. Our results showed that the transcript detected consistently in male gonads and variably in somatic organs represents XIST antisense RNA and that XIST sense and antisense RNAs are co-expressed in female somatic tissues and cultured cells including cells of sex chromosome aneuploids (XXY and XXX). Our results, which differ from those of other investigators in this area, are discussed in the light of the recently reported differences in the expression pattern of murine Xist/Tsix loci and their structural and functional differences in different mammalian species.

Inhibitory effects of anti-sense PTTG on malignant phenotype of human ovarian carcinoma cell line SK-OV-3

To construct eukaryotic expression vector expressing full length anti-sense pituitary tumor transforming gene (PTTG) mRNA and observe its blocking effect on the potential invasion of human ovarian carcinoma cell line SK-OV-3. PCR primers containing designed enzyme cut sites were used for cloning full-length PTTG gene fragment, and the resulting PCR product was inserted into the eukaryotic vector pcDNA3.1 in the antisense direction. The recombinant vector was then transfected into SK-OV-3 by Lipofectamine. The positive cell clone was screened by G418, PTTG and bFGF at protein level expression were detected by Western blot. The biological behavior change of transfection positive cells was observed by colony formation in soft agar assay. Our results showed that SK-OV-3 clones stably expressing full-length recombinant pcDNA3.1-PTTGas were obtained. The expressions of PTTG and bFGF protein in transfected cells were decreased by 61.5% and 52.3%, respectively as compared with non-transfected ones. The number of colony formation was reduced significantly in transfected cells as compared with empty vector transfected and non-transfected cells. It is concluded that the recombinant vector pcDNA3.1-PTTGas is a novel tool and provides an alternative anti-sense gene therapy targeted at PTTG in human carcinoma.

MYH9 spectrum of autosomal-dominant giant platelet syndromes: unexpected association with fibulin-1 variant-D inactivation

The autosomal-dominant giant platelet syndromes (Fechtner, Epstein, and Sebastian platelet syndromes and May-Hegglin anomaly) represent a group of disorders characterized by variable degrees of macrothrombocytopenia with further combinations of neutrophil inclusion bodies and Alport-like syndrome manifestations, namely, deafness, renal disease, and eye abnormalities. The disease-causing gene of these giant platelet syndromes was previously mapped by us to chromosome 22. Following their successful mapping, these syndromes were shown to represent a broad phenotypic spectrum of disorders caused by different mutations in the nonmuscle myosin heavy chain 9 gene (MYH9). In this study, we examined the potential role of another gene, fibulin-1, encoding an extracellular matrix protein as a disease modifier. Eight unrelated families with autosomal-dominant giant platelet syndromes were studied for DNA sequence mutations and expression of the four fibulin-1 splice variants (A-D). A mutation in the splice acceptor site of fibulin-1 exon 19 was found in affected individuals of the Israeli Fechtner family, whereas no MYH9 mutations were identified. Unexpectedly, fibulin-1 variant D expression was absent in affected individuals from all eight families and coupled with expression of a putative antisense RNA. Transfection of the putative antisense RNA into H1299 cells abolished variant D expression. Based on the observation that only affected individuals lack variant D expression and demonstrate antisense RNA overexpression, we suggest that these autosomal-dominant giant platelet syndromes are associated, and may be modified, by aberrant antisense gene regulation of the fibulin-1 gene.

Kalirin, a multifunctional Rho guanine nucleotide exchange factor, is necessary for maintenance of hippocampal pyramidal neuron dendrites and dendritic spines

The structures of dendritic spines and the dendritic tree, key determinants of neuronal function, are regulated by diverse inputs that affect many scaffolding and signaling molecules. Nevertheless, here we show that reduced expression of a single gene results in loss of dendritic spines and a decrease in dendritic complexity. Kalirin, a dual Rho GDP-GTP exchange factor, causes spine formation when overexpressed. Reduced expression of Kalirin in CA1 hippocampal neurons resulted in a reduction in linear spine density, with dispersion of postsynaptic density markers and elimination of presynaptic endings. Simplification of the apical dendritic tree preceded simplification of basal dendrites. Pyramidal cell axons were not dramatically altered. Although many factors determine dendrite shape and spine formation, expression of Kalirin is necessary for the normal function of these many regulatory elements.

Inhibition of Staphylococcus aureus pathogenesis in vitro and in vivo by RAP-binding peptides

Staphylococcus aureus cause many diseases by producing toxins, whose synthesis is regulated by quorum-sensing mechanisms. S. aureus secretes a protein termed RNAIII activating protein (RAP) which autoinduces toxin production via the phosphorylation of is target protein TRAP. Mice vaccinated with RAP were protected from S. aureus infection, suggesting that RAP is an useful target for selecting potential therapeutic molecules to inhibit S. aureus pathogenesis. We show here that RAP (native and recombinant) was used to select RAP-binding peptides (RBPs) from a random 12-mer phage-displayed peptide library. Two RBPs were shown to inhibit RNAIII production in vitro (used a marker for pathogenesis). The peptide WPFAHWPWQYPR, which had the strongest inhibitory activity, was chemically synthesized and also expressed in Escherichia coli as a GST-fusion. Both synthetic peptide and GST-fusion peptide decreased RNAIII levels in a dose-dependent manner. The GST-fusion peptide was also shown to protect mice from a S. aureus infection in vivo (tested in a murine cutaneous S. aureus infection model). Our results suggest the potential use of RAP-binding proteins in treating clinical S. aureus infections.

Expression of U1 small nuclear ribonucleoprotein 70K antisense transcript using APETALA3 promoter suppresses the development of sepals and petals

U1 small nuclear ribonucleoprotein (snRNP)-70K (U1-70K), a U1 snRNP-specific protein, is involved in the early stages of spliceosome formation. In non-plant systems, it is involved in constitutive and alternative splicing. It has been shown that U1snRNP is dispensable for in vitro splicing of some animal pre-mRNAs, and inactivation of U1-70K in yeast (Saccharomyces cerevisiae) is not lethal. As in yeast and humans (Homo sapiens), plant U1-70K is coded by a single gene. In this study, we blocked the expression of Arabidopsis U1-70K in petals and stamens by expressing U1-70K antisense transcript using the AP3 (APETALA3) promoter specific to these floral organs. Flowers of transgenic Arabidopsis plants expressing U1-70K antisense transcript showed partially developed stamens and petals that are arrested at different stages of development. In some transgenic lines, flowers have rudimentary petals and stamens and are male sterile. The severity of the phenotype is correlated with the level of the antisense transcript. Molecular analysis of transgenic plants has confirmed that the observed phenotype is not due to disruption of whorl-specific homeotic genes, AP3 or PISTILLATA, responsible for petal and stamen development. The AP3 transcript was not detected in transgenic flowers with severe phenotype. Flowers of Arabidopsis plants transformed with a reporter gene driven by the same promoter showed no abnormalities. These results show that U1-70K is necessary for the development of sepals and petals and is an essential gene in plants.

Loss of imprinting of IGF2 sense and antisense transcripts in Wilms' tumor

Human insulin-like growth factor II gene (IGF2) is overexpressed, and its imprinting is disrupted in many tumors, including Wilms' tumor. A transcript that is antisense to IGF2, IGF2-antisense (IGF2-AS), is transcribed from within IGF2 in a reverse orientation. This transcript is also maternally imprinted and overexpressed in Wilms' tumor. IGF2-AS was detected as a 2.2 kb mRNA in Hep 3B cells by Northern blotting, and it encodes a putative 168 amino acid peptide. An alternative splicing mRNA observed predominantly in adult liver encodes an additional putative 199 amino acid peptide. We have examined the expression of IGF2 and IGF2-AS in normal tissue, breast and ovarian tumors, and 25 informative, well-characterized Wilms' tumors and determined the relationship between IGF2 and IGF2-AS imprinting. IGF2-AS was expressed at levels comparable with IGF2 sense expression derived from promoters P1 and P2 in normal tissue and in breast, ovarian, and Wilms' tumor tissues. In Wilms' tumors that demonstrate maintenance of imprinting of IGF2, IGF2-AS was imprinted. In contrast, in tumors which demonstrate LOI of IGF2, only two of six tumors showed loss of imprinting of IGF2-AS, whereas four of six tumors demonstrated maintenance of imprinting for IGF2-AS. The discrepancy between IGF2 and IGF2-AS loss of imprinting in some tumors demonstrates the control complexity of the imprinting status of the various transcripts derived from the IGF2 gene.

Calcyclin (S100A6) regulates pulmonary fibroblast proliferation, morphology, and cytoskeletal organization in vitro

Calcyclin (S100A6) is a member of the S100A family of calcium binding proteins. While the precise function of calcyclin is unknown, calcyclin expression is associated with cell proliferation and calcyclin is expressed in several types of cancer phenotypes. In the present study, the functional role of calcyclin was further elucidated in pulmonary fibroblasts. Antisense S100A6 RNA expression inhibited serum and mechanical strain-induced fibroblast proliferation. This attenuated proliferative response was accompanied by a flattened, spread cell morphology, and disruption of tropomyosin labeled microfilaments. Changes in cytoskeletal organization did not correspond with a decrease in tropomyosin levels. These observations suggest a role for calcyclin in modulating calcium dependent signaling events that regulate progression through the cell cycle. J. Cell. Biochem. 88: 848-854, 2003.

Role for antisense RNA in regulating circadian clock function in Neurospora crassa

The prevalence of antisense RNA in eukaryotes is not known and only a few naturally occurring antisense transcripts have been assigned a function. However, the recent identification of a large number of putative antisense transcripts strengthens the view that antisense RNAs might affect a wider variety of processes than previously thought. Here we show that in the model organism Neurospora crassa entrainment of the circadian clock, which is critical for the correct temporal expression of genes and their products, is controlled partly by an antisense RNA arising from a clock component locus. In a wild-type strain, levels of antisense frequency (frq) transcripts cycle in antiphase to sense frq transcripts in the dark, and are inducible by light. In mutant strains in which the induction of antisense frq RNA by light is abolished, the time of the internal clock is delayed relative to the wild-type strain, and resetting of the clock by light is altered. These data provide an unexpected link between antisense RNA and circadian timing and provide a new example of a eukaryotic cellular process regulated by naturally occurring antisense RNA.

Stable expression of antisense urokinase mRNA inhibits the proliferation and invasion of human hepatocellular carcinoma cells

Urokinase-type plasminogen activator (u-PA) plays a key role in malignant tumor behavior. We have previously shown that the expression of high levels of u-PA mRNA in human hepatocellular carcinoma (HCC) biopsies was inversely correlated with the survival of the patients. In order to evaluate the involvement of u-PA in the invasive and infiltrating properties of HCC cells, the SKHep1C3 cell line was stably transfected with an expression vector containing the 5' portion (257 bp) of u-PA cDNA in the antisense orientation. u-PA mRNA expression and its protein level and enzymatic activity were specifically inhibited in the antisense transfectants. A comparable inhibition of the u-PA receptor (u-PAR) mRNA and protein was also evidenced in the antisense transfected cells compared with the control ones. At the functional level, the SKHep1C3-AS cells showed a significant reduction in proliferation, Matrigel invasion, and motility assays compared to parental and vector-alone cells. These results indicate that u-PA is an essential factor in the growth and invasiveness of human hepatocarcinoma cells. Antisense u-PA strategy might be a potential approach to reduce tumor growth as well as the invasive capacity of the malignant cells in HCC.

[Construction of eukaryotic expression vector of hMTH1 gene antisense RNA]

OBJECTIVE

To construct pEGFP-C1-T vector, an eukaryotic expression plasmid of hMTH1 gene antisense RNA.

METHODS

The conservative region of hMTH1 gene was amplified by RT-PCR after total RNA being extracted from human embryo lung fibroblast (HLF) and then cloned into pGEM-T vector. After the recombinant plasmid was certified by DNA sequencing, the conservative region of hMTH1 gene was inserted into pEGFP-C1 vector reversedly and pEGFP-C1-T vector was constructed. The efficiency of antisense inhibition was verified by Western blotting after cell transfection.

RESULTS

423 bp fragment including conservative region of hMTH1 gene was obtained by RT-PCR. After cloned by pGEM-T vector and certified by DNA sequencing, pEGFP-C1-T vector was successfully constructed by means of recombinant DNA technology. Additionally pEGFP-C1-T vector could efficiently decrease hMTH1 protein level by 46%.

CONCLUSION

The efficient expression vector of hMTH1 gene antisense RNA, pEGFP-C1-T has been constructed successfully.

Construction of antisense RNA expression plasmid for u-PAR and its transfection to highly invasive PC-3M cell subclones

To evaluate the specific inhibition of antisense u-PAR on the u-PAR expressions in highly invasive cell subclones and to determine its blocking function in the invasion by those cells, a cDNA fragment of u-PAR obtained by RT-PCR was inserted into a plasmid vector named pcDNA3 in antisense orientation. Then the antisense u-PAR recombinant was transfected into highly invasive cell subclones. The u-PAR expression in neo-resistant cells was examined by RT-PCR and immunohistochemical assay. Compared to the control cells, the content of mRNA and protein of u-PAR in transfected cells decreased sharply, and the rate of inhibition was 53% and 73%, respectively, indicating that an antisense u-PAR might have played a specific inhibitory role in its expression in the cells, which may provide a good cell model for making further investigation of the inhibitory effects of the antisense u-PAR on invasion in highly invasive cell subclones of human prostate carcinoma.

The effects of adrenalectomy and aldosterone replacement in transgenic mice expressing antisense RNA to the type 2 glucocorticoid receptor

Bilateral adrenalectomy (ADX) either prevents or attenuates obesity in several animal models. Mice that express an antisense RNA to the glucocorticoid receptor (GCR) are obese. The present study was conducted to examine the effects of ADX and aldosterone (ALDO) replacement on the rate of weight gain and body composition of mice bearing an antisense GCR gene construct. Twenty-eight male transgenic mice bearing the antisense GCR construct and 16 male B6C/3F1 mice were either bilaterally ADX or given sham operations. At the time of surgery, some of the ADX mice and all of the sham-operated mice were implanted with 100-mg cholesterol (CHOL) pellets inserted subcutaneously in the subscapular region. The remaining ADX mice were implanted with 100-mg 1% w/w ALDO pellets using CHOL as vehicle. All mice were returned to their home cages for 2 weeks. They were then decapitated and the blood was collected for corticosterone, ALDO, insulin, and leptin radioimmunoassay. Carcasses were eviscerated and prepared for gravimetric analyses, including bomb calorimetry. ADX resulted in a significant drop in carcass fat in both transgenic and wildtype groups. ALDO prevented the decrease in carcass fat in both groups. Two weeks after ADX, transgenic mice were as fat as sham-operated wildtype controls, whereas both sham-operated and ALDO-treated transgenic groups were significantly fatter. Despite observing a reliable decrease in carcass fat following ADX, no corresponding decrease in circulating leptin was found.

Effects of partial suppression of ribosomal protein S6 on organ formation in Arabidopsis thaliana

An expression library of Arabidopsis thaliana cDNAs was randomly introduced into A. thaliana. The transformant pool was used to obtain a line, c105, with reduced apical dominance and irregular positioning of leaves and flowers. The inserted DNA was a 3'-fragment of the ribosomal protein S6 gene with antisense orientation. The transcriptional level of the ribosomal protein S6 was lower in c105 than in the wild-type plant. Introduction of the same fragment into the wild-type plant gave phenotypes similar to those of c105, so the phenotypes of c105 were due to the S6 antisense expression. The phenotypes suggest selectively reduced function of specific proteins rather than an overall decrease in protein function caused by defective ribosomal biogenesis.

Insulin inhibits PDGF-directed VSMC migration via NO/ cGMP increase of MKP-1 and its inactivation of MAPKs

In this study, we examined the role of insulin in the control of vascular smooth muscle cell (VSMC) migration in the normal vasculature. Platelet-derived growth factor (PDGF) increased VSMC migration, which was inhibited by pretreatment with insulin in a dose-dependent manner. Insulin also caused a 60% decrease in PDGF-stimulated mitogen-activated protein kinase (MAPK) phosphorylation and activation. Insulin inhibition of MAPK was accompanied by a rapid induction of MAPK phosphatase (MKP-1), which inactivates MAPKs by dephosphorylation. Pretreatment with inhibitors of the nitric oxide (NO)/cGMP pathway, blocked insulin-induced MKP-1 expression and restored PDGF-stimulated MAPK activation and migration. In contrast, adenoviral infection of VSMCs with MKP-1 or cGMP-dependent protein kinase Ialpha (cGK Ialpha), the downstream effector of cGMP signaling, blocked the activation of MAPK and prevented PDGF-directed VSMC migration. Expression of antisense MKP-1 RNA prevented insulin's inhibitory effect and restored PDGF-directed VSMC migration and MAPK phosphorylation. We conclude that insulin inhibition of VSMC migration may be mediated in part by NO/cGMP/cGK Ialpha induction of MKP-1 and consequent inactivation of MAPKs.

Identification of novel candidate genes in the diffuse panbronchiolitis critical region of the class I human MHC

Diffuse panbronchiolitis (DPB) is an unusual form of bronchiolar disease affecting exclusively East Asians. Strong associations of DPB with the class I human leukocyte antigens HLA-B54 in Japan and China and HLA-A11 in Korea suggest that the susceptible locus for DPB is located between the HLA-B and HLA-A genes. We have previously reported that the susceptibility gene for DPB could be localized within a 200-kb segment between the S and TFIIH loci in the HLA class I region, using refined microsatellite-based association mapping. However, no genes have been recognized in this candidate region to date. In order to identify a novel candidate gene for DPB from this segment, the expressed sequence tag databases were searched using the genomic sequence. As a result, a cDNA clone was isolated from a human lung cDNA library. This gene, designated C6orf37 (Chromosome 6 open reading frame 37), spans approximately 2.5 kb and consists of two exons encoding a 235-amino acid protein, sharing homology with the mucin-like domain of human zonadhesin, which is a sperm multiple-domain transmembrane protein with the sperm zona pellucida binding activity. Unexpectedly, RT-PCR analysis detected transcripts from the anti-sense DNA strand of this C6orf37 locus. The gene designated as C6orf37OS (C6orf37 Opposite Strand) and represented by these anti-sense transcripts contained no open reading frame. The transcripts from C6orf37 and C6orf37OS were observed in numerous tissues, with most-abundant expression in lung, kidney, and testis. Taken together, these results, especially the abundant expression in lung, indicate that C6orf37 and C6orf37OS are excellent candidate genes for DPB.

Silencing of the aspergillopepsin B (pepB) gene of Aspergillus awamori by antisense RNA expression or protease removal by gene disruption results in a large increase in thaumatin production

Aspergillopepsin B was identified in culture broths of Aspergillus awamori by in situ detection of its proteolytic activity and by immunodetection with anti-aspergillopepsin B antibodies. Severe thaumatin degradation was observed after in vitro treatment of thaumatin with purified aspergillopepsin B. The pepB gene encoding aspergillopepsin B of A. awamori was cloned and characterized. It is located in chromosome IV of A. awamori, as shown by pulsed-field gel electrophoresis, and encodes a protein of 282 amino acids with high similarity to the aspergillopepsin B of Aspergillus niger var. macrosporus. The pepB gene is expressed at high rates as a monocistronic 1.0-kb transcript in media with casein at acidic pH values. An antisense cassette constructed by inserting the pepB gene in the antisense orientation downstream from the gpdA promoter resulted in a good level of antisense mRNA, as shown by reverse transcription-PCR. Partial silencing of the pepB gene by the antisense mRNA resulted in a 31% increase in thaumatin yield. However, significant residual degradation of thaumatin still occurred. To completely remove aspergillopepsin B, the pepB gene was deleted by double crossover. Two of the selected transformants lacked the endogenous pepB gene and did not form aspergillopepsin B. Thaumatin yields increased by between 45% in transformant APB 7/25 and 125% in transformant 7/36 with respect to the parental strain. Reduction of proteolytic degradation by gene silencing with antisense mRNA or total removal of the aspergillopepsin B by directed gene deletion was a very useful method for improving thaumatin production in A. awamori.

DAP kinase and DRP-1 mediate membrane blebbing and the formation of autophagic vesicles during programmed cell death

Death-associated protein kinase (DAPk) and DAPk-related protein kinase (DRP)-1 proteins are Ca+2/calmodulin-regulated Ser/Thr death kinases whose precise roles in programmed cell death are still mostly unknown. In this study, we dissected the subcellular events in which these kinases are involved during cell death. Expression of each of these DAPk subfamily members in their activated forms triggered two major cytoplasmic events: membrane blebbing, characteristic of several types of cell death, and extensive autophagy, which is typical of autophagic (type II) programmed cell death. These two different cellular outcomes were totally independent of caspase activity. It was also found that dominant negative mutants of DAPk or DRP-1 reduced membrane blebbing during the p55/tumor necrosis factor receptor 1-induced type I apoptosis but did not prevent nuclear fragmentation. In addition, expression of the dominant negative mutant of DRP-1 or of DAPk antisense mRNA reduced autophagy induced by antiestrogens, amino acid starvation, or administration of interferon-gamma. Thus, both endogenous DAPk and DRP-1 possess rate-limiting functions in these two distinct cytoplasmic events. Finally, immunogold staining showed that DRP-1 is localized inside the autophagic vesicles, suggesting a direct involvement of this kinase in the process of autophagy.

The expression of gbx-2 during zebrafish embryogenesis

Gbx-2 is a homeobox gene essential for normal development of the midbrain and the anterior hindbrain. Zebrafish gbx-2 shares an overall similarity of 67.8, 68.1, 60.6 and 66.5% in amino acid sequence to human, mouse, chick and Xenopus Gbx-2, respectively. The expression of zebrafish gbx-2 is initially, before the completion of epiboly, restricted to the prospective posterior midbrain. The expression remains detectable until the end of pharyngula period. The gbx-2 mRNA is also detected in the otic vesicles, the dorsoposterior telencephalon, the rostral branchial arches, the pronephric duct and median fin fold.

Endogenous von Hippel-Lindau tumor suppressor protein regulates catecholaminergic phenotype in PC12 cells

Loss of von Hippel-Lindau (VHL) gene function leads to VHL disease, which is characterized by vascular tumors of the central nervous system, renal clear cell carcinomas, and pheochromocytomas. Pheochromocytomas express high levels of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis. PC12 cells that express VHL antisense RNA had 5-10-fold reduced levels of endogenous pVHL and 2-3-fold increased levels of TH protein and mRNA. Nuclear run-on analysis revealed an augmentation of TH gene transcription with enhanced efficiency of transcript elongation in the 3' region of the gene. Transient coexpression of the VHL antisense RNA with a TH promoter reporter construct increased TH promoter activity by 2-3-fold. A decrease in pVHL accumulation also resulted in an increase in TH mRNA accumulation and transcription of the TH gene during hypoxia. This is the first evidence that endogenous pVHL is a physiological regulator of the catecholaminergic phenotype. Thus, loss of pVHL function may be causative in pheochromocytoma-associated hypercatecholaminemia and arterial hypertension.