Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytokine-driven activation of hepatic stellate cells (HSC) in tissue injury and inflammation is a key pathogenetic event in liver fibrogenesis leading to an expanded pool of matrix producing myofibroblasts (MFB) which represent the transformed counterpart of HSC. We hypothesize that expansion of the pool of MFB might also be accomplished by modulation of apoptosis, which plays an opposite and complementary role to mitosis in the cellular homeostasis. We characterized the susceptibility of HSC in primary culture and of MFB in secondary culture to apoptosis induced by the soluble Fas ligand (sFasL) and related the effects to the expression levels of Fas (APO-1/CD95) and some major proapoptotic and contra-apoptotic protooncogenes. MFB showed a dose-dependent apoptotic reaction upon exposure to sFasL as evidenced by a strong increase of nucleosomal DNA fragments, loss of cellular DNA, positive TUNEL reaction, and annexin staining. The effect was found only if protein synthesis (cycloheximide) or RNA synthesis (actinomycin D) were arrested. HSC maintained for various times in primary culture were completely resistant to sFasL in combination with cycloheximide, but in late primary cultures (day 7 onward) an increasing susceptibility to sFasL-mediated apoptosis was developed. By semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis and alkaline phosphatase-anti-alkaline phosphatase staining Fas receptor was identified both in HSC and MFB at comparable expression levels. The expression of the contra-apoptotic protooncogenes bcl-2 and bcl-xl was found to be much stronger in early HSC than in late HSC and MFB as shown by ribonuclease protection assay. The expression of bcl-2 was additionally confirmed by semiquantitative RT-PCR and immunoblotting. Proapoptotic bax was found in comparable quantities at the RNA level in HSC and MFB but at the protein level MFB showed increased bax expression. It is concluded that transformation of HSC to MFB is paralleled by an increasing sensitivity to sFasL-mediated apoptosis, which might be related to a strong decrease of bcl-2 and bcl-xl expression, leading to a preponderance of proapoptotic gene expression in MFB. Modulation of apoptotic susceptibility of transforming HSC could be an important complementary pathway in the pathogenesis of fibrosis.
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PMID:Transformation-dependent susceptibility of rat hepatic stellate cells to apoptosis induced by soluble Fas ligand. 969 16

The prostate gland in adult male rats is highly dependent on androgenic steroids. Castration initiates the regression of this tissue through a process involving the loss of the vast majority of cells by means of apoptosis. We studied this well characterized in vivo model of apoptosis to evaluate how the expression of two particular gene products, bcl-2 and bax, known to be important for the regulation of apoptosis were affected by castration. An RNase protection assay designed to quantify the levels of bax mRNA showed that this transcript was transiently elevated after castration, reaching a peak in expression at 3 days and declining thereafter. In contrast, bcl-2 mRNA expression was continuously elevated over a period of up to 7 days after castration. The distinct changes in the expression of the mRNAs encoding these two genes were confirmed by an in situ hybridization analysis of regressing rat ventral prostate tissues. The elevation in mRNAs were apparently restricted to the secretory epithelial cells of the gland, the cellular compartment of the tissue most affected by castration. Finally, SDS - PAGE/Western blot analysis of bax and bcl-2 protein expression in the regressing rat prostate gland with bax and bcl-2-specific antibodies showed that the changes in the bax and bcl-2 protein levels were similar and consistent to that found for the mRNAs. In summary, the expression of both bax and bcl-2 gene products are uniquely modulated during castration-induced regression of the rat ventral prostate gland. The changes we observed identify a transient but marked increase in the bax/bcl-2 expression ratio of the tissue that peaks on the second and third days after castration, coinciding with the peak periods of prostate cell apoptosis. These data support previous studies done on in vitro systems wherein it was shown that the bax/bcl-2 ratio determines the apoptotic potential of a cell.
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PMID:An elevated bax/bcl-2 ratio corresponds with the onset of prostate epithelial cell apoptosis. 1020 May 47

Epidemiology suggests a possible relationship between exposure to power frequency magnetic fields (EMF) and breast cancer. One mechanism through which EMF could stimulate breast cancer induction is via altered expression of oncogenes and/or tumor suppressor genes that regulate normal and neoplastic growth. To evaluate the hypothesis that EMF action in the breast is mediated by alterations in gene expression, transcript levels of c-myc and a battery of other cancer-associated genes were quantitated in human breast epithelial cells exposed to pure, linearly polarized 60 Hz EMF with low harmonic distortion. HBL-100 cells and normal (non-transformed) human mammary epithelial cells were exposed to EMF flux densities of 0.1, 1.0 and 10.0 Gauss (G) for periods ranging from 20 min to 24 h; concurrent sham controls were exposed to ambient fields (<0.001 G) only. Gene expression was quantitated using ribonuclease protection assays. EMF exposure had no statistically significant effect on basal levels of c-myc transcripts in either human breast cell model, and had no effect on alterations in c-myc expression induced by 12-O-tetradecanoylphorbol-13-acetate. Transcript levels of c-erbB-2, p53, p21, GADD45, bax, bcl-x, mcl-1, and c-fos were also unaffected by EMF exposure. These results suggest that EMF is unlikely to influence breast cancer induction through a mechanism involving altered expression of these genes.
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PMID:Gene expression in human breast epithelial cells exposed to 60 Hz magnetic fields. 1042 19

Cells respond to genotoxic stress by activation of many genes, including the tumor suppressor p53. p53 activates transcriptionally target genes, such as p21waf1 and gadd45, which can lead to cell cycle arrest, or bax, which can lead to cell death. We examined the response to genotoxic stress in two hematopoietic cell lines that harbor either wild-type (MOLT-4) or a mutant p53 with a codon 161 mutation (U266). We adapted a multiprobe RNase protection assay (RPA) to determine the steady-state RNA levels, and in combination with nuclear runoff assays, transcriptional rates of multiple stress-induced genes. We found a differential activation of growth arrest and cell death-specific p53 target genes in cells with wild-type or mutant p53. Our results show that genotoxic stress can activate the p21waf1 and gadd45 genes in both cell lines. However, the bax gene was not induced in U266 cells. Bax and gadd45 gene induction could be efficiently blocked by pretreating the cells with the antioxidant compound pyrrolidine dithiocarbamate, suggesting that oxidative stress was involved in these responses. Induction of all three genes in MOLT-4 cells was clearly at the transcriptional level, because we detected transcriptional activity by nuclear runoff RPA assays, and transfection with a consensus p53 binding sequence. U266 cells did not activate the same reporter, in spite of the upregulation of p21waf1 and gadd45 RNA levels. However, the p21waf1-reporter constructs containing 0.9 to 2.4 kb of the native p21 promoter were potently activated in U266 cells. These results indicate a differential regulation of p53 target genes in cells containing wild-type or codon 161 mutant p53.
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PMID:Differential upregulation of p53-responsive genes by genotoxic stress in hematopoietic cells containing wild-type and mutant p53. 1079 22

Apoptosis was detected in different muscular diseases, including severe dystrophin deficiency, but apoptotic mechanisms are not completely described in adult skeletal muscle. Studying patients affected by Duchenne muscular dystrophy (DMD) and by facio-scapulo-humeral dystrophy (FSHD) we showed an increase of apoptotic myonuclei, bax, and bcl-2-positive myofibers. Positive correlation was detected between apoptotic nuclei and bax expression (p < 0.01). Expression of caspases was analyzed by RNase protection. Caspase transcript was not detected in normal skeletal muscles. DMD muscles expressed caspase 8, 3, 5, 2, 7 and Granzyme B mRNAs. Low levels of caspase 6, 3, and Granzyme B transcripts were detected in FSHD patients. Tissue levels of caspase 3 protein significantly correlated with apoptotic myonuclei (p < 0.05) and with bax expression (p < 0.01). In all DMD cases the activity of caspase 3 was increased, while the FSHD samples were heterogeneous. These data indicate that human skeletal muscle fibers. during the dystrophic process, modulate the expression of caspases and that caspase 3 is involved in myofiber cell death. opening new perspective in the pharmacological treatments of muscular dystrophies, such as the use of caspase inhibitors.
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PMID:Caspase 3 expression correlates with skeletal muscle apoptosis in Duchenne and facioscapulo human muscular dystrophy. A potential target for pharmacological treatment? 1124 14

The Myc family of genes regulates proliferation, differentiation, and apoptosis. Temporal expression of Myc family genes and several pro-apoptotic genes were investigated during Swiss Webster mice organogenesis after maternal treatment with an oral dose of 100 mg/kg trans-retinoic acid (RA) or vehicle on day 10 post-coitum. Reverse transcriptase-polymerase chain reaction and ribonuclease protection assay revealed decreased c-myc expression at 48 h followed by an increase at 72 h in fetuses from RA-treated dams. Increased c-Myc protein was detected at 72 h in the RA-treated group. In utero RA-treatment resulted in decreased expression of max, mad, caspases, bax, and bad genes at 48 h. Terminal uridinetriphosphate nick end-labeling (TUNEL) analysis revealed increased apoptosis at 24-48 h, followed by decreased apoptosis 72 h after in utero RA-exposure, which correlated with the decreased expression of pro-apoptotic genes noted at 48 h. Further investigations are needed to understand the role of Myc family genes during RA-mediated teratogenesis.
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PMID:Expression of c-Myc and other apoptosis-related genes in Swiss Webster mouse fetuses after maternal exposure to all trans-retinoic acid. 1212 97

In order to better understand the host response to an infection with Neisseria gonorrhoeae, microarray technology was used to analyse the gene expression profile between uninfected and infected human urethral epithelium. The anti-apoptotic genes bfl-1, cox-2 and c-IAP-2 were identified to be upregulated approximately eight-, four- or twofold, respectively, following infection. Subsequent assays including RT-PCR, real time RT-PCR and RNase protection confirmed the increased expression of these apoptotic regulators, and identified that a fourth anti-apoptotic factor, mcl-1, is also upregulated. RT-PCR and RNase protection also showed that key pro-apoptotic factors including bax, bad and bak do not change in expression. Furthermore, our studies demonstrated that infection with the gonococcus partially protects urethral epithelium from apoptosis induced by the protein kinase inhibitor, staurosporine (STS). This work shows that following infection with Neisseria gonorrhoeae, several host anti-apoptotic factors are upregulated. In addition, a gonococcal infection protects host cells from subsequent STS-induced death. The regulation of host cell death by the gonococcus may represent a mechanism employed by this pathogen to survive and proliferate in host epithelium.
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PMID:Infection of human urethral epithelium with Neisseria gonorrhoeae elicits an upregulation of host anti-apoptotic factors and protects cells from staurosporine-induced apoptosis. 1286 14

Fumonisin B1 (FB1), a mycotoxin, is a potent inhibitor of ceramide synthase, and produces organ-, species-, and even gender-specific toxic responses in animals. The hepatotoxic response of FB1 in mice involves accumulation of free sphingoid bases and induction of inflammatory cytokines including tumor necrosis factor alpha (TNFalpha). The FB1-induced hepatotoxic responses were reduced in mice lacking TNFalpha receptor (TNFR) 1 or TNFR2. However, the hepatotoxicity was exacerbated in mice lacking TNFalpha. We therefore investigated the modulation of various other apoptotic signaling factors in TNFalpha-knockout (TKO) mice compared to wild-type (WT) strain after repeated daily subcutaneous injections of 2.25 mg/kg FB1 treatment for 5 days. Expression of various signaling genes in liver was evaluated by ribonuclease protection assay. Expression of CD95-ligand (FasL) was more than doubled in TKO animals after FB1 whereas it was unaltered in the WT group. FB1 did not alter CD95 expression in either strain; however, expressions of TRAIL, and downstream signaling factors FADD, TRADD, and caspase 8 were higher in FB1-treated TKO mice than in the corresponding WT animals. The TKO strain had a higher constitutive expression of apoptotic factors except CD95L. In addition to the CD95 and TNFalpha systems, the expression of apoptotic molecules bcl-2, b-myc, c-myc, bax, max, mad and IL1alpha was induced by FB1 in TKO mice to a greater extent than in WT animals; many of these factors also had a higher constitutive expression in TKO animals than WT mice. Results indicated that FB1 can induce CD95 modulated signaling when TNFalpha is absent. Differential constitutive expression of apoptotic genes in TKO mice may explain their increased sensitivity to FB1. These results are important in characterizing the modulating effect of TNFalpha on apoptotic signaling and in explaining the unexpected sensitivity of mice lacking this cytokine in response to hepatotoxic xenobiotics.
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PMID:Increased expression of CD95-ligand and other apoptotic signaling factors by fumonisin B1, a hepatotoxic mycotoxin, in livers of mice lacking tumor necrosis factor alpha. 1459 19

Many studies have been undertaken to investigate the mechanisms of skin differentiation. In particular, growth factors and hormones are believed to play important roles in skin proliferation, differentiation and survival. Insulin-like growth factor-1 (IGF-1) has been identified as a survival factor in many tissues including the skin, but the molecular mechanism of IGF-1 in epidermal differentiation is not completely understood. Neonatal mouse skin is useful for studying changes in gene expression, as the mitotic activity of skin cells changes shortly after birth. Using RNA differential display (DD), a 357-nt message that is specifically expressed in the epidermal keratinocytes of IGF-1-injected newborn mice but not in controls, has been identified. Confirmation of expression of this gene by ribonuclease protection assay (RPA) showed that its mRNA expression in the epidermal keratinocytes is induced by IGF-1. Using RNA ligase-mediated rapid amplification of 5' cDNA ends (RLM-5'-RACE), we have successfully isolated a 3473-bp full-length gene, c98, that has 97% sequence homology to a bcl-2-like gene, bcl-w. The latter has been identified as a proto-oncogene in several murine myeloid cell lines. Amino acid sequence analysis of the c98 showed that it has 97% sequence identity to the bcl-w protein and possesses bcl-2 homology domains (BH) 1, 2 and 3. Immunoblotting data revealed similar increases of c98 protein expression to its mRNA expression in the keratinocytes of IGF-1-injected animals. Weak expression of other bcl-2 family member proteins, bax, bcl-2 and bcl-xL, were also found in the immunoblots. Additionally, IGF-1 was found to be able to protect epidermal keratinocytes from dexamethasone (DEX)-induced apoptosis, based on the findings that after the cells were treated with DEX, DNA laddering was present in the control mice but not in those injected with IGF-1. Further, using a photometric enzyme-linked immunoassay to quantitate keratinocyte death, we found that after addition of DEX, the amounts of cytoplasmic histone-associated DNA fragments were not significantly (P>0.05) different in IGF-1-treated cells compared with untreated control cells during the high mitotic stage of skin epidermis. To assess the role of c98 in these anti-apoptotic processes, we have generated a recombinant plasmid that contains an expression vector and c98 and transfected this plasmid into the keratinocytes from mice without IGF-1-treatment. Expression of the c98 protein was found to completely (P>0.05) block DEX-induced apoptosis after cell transfection. Taken together, our current data demonstrated that IGF-1 plays an anti-apoptotic role in the DEX-induced apoptosis in epidermal keratinocytes and this, at least in part, may be mediated through expression of c98.
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PMID:Mouse keratinocytes express c98, a novel gene homologous to bcl-2, that is stimulated by insulin-like growth factor 1 and prevents dexamethasone-induced apoptosis. 1474 7

Cell proliferation and apoptosis are controlled by tightly orchestrated signaling pathways that culminate in transcriptional activation/repression of multiple proteins. Dysregulation of cell cycle and/or apoptosis control may lead to genomic instability, neoplastic transformation and tumor progression. Under certain conditions, some hexavalent chromium [Cr(VI)] compounds are toxic and carcinogenic in the human respiratory tract, and we have shown that they induce apoptosis and/or cell cycle arrest in a p53-dependent fashion. There is increasing evidence linking extracellular signal-regulated kinase (ERK) activation with the DNA damage response, by both p53-dependent and -independent mechanisms. Here, the aim was to study the effect of Cr(VI) transcriptional regulation of key cell cycle inhibitors and pro- and anti-apoptotic proteins, as well as the role of ERK activation in the Cr(VI) genotoxic response. Diploid human lung fibroblasts were incubated with 3-9 uM Na2CrO4, and RNA was isolated at 4, 8, and 24 h, as well as 24 h after Cr(VI) exposure was terminated (recovery). mRNA expression was quantitated by RNase protection assay with a 32P-labeled multi-transcript probe containing gene sequences for the cdk inhibitors, p21waf1/cip1, p27kip1, p16INK4a, p15INK4b; the pro-apoptotic proteins bcl-XS and bax; the anti-apoptotic proteins bcl-W, bcl-XL, and bcl2, GADD45, and cyclin A. In general, bcl-W and bcl-XL expression were both downregulated after Cr exposure, to around 50% at 24 h, which was more pronounced after the recovery period. At Cr(VI) concentrations < or = 6 uM, bcl2 expression was upregulated. Of particular interest is that bax expression was reduced, in a dose and time-dependent fashion, however that of bcl-XS was elevated by nearly 3-fold after 8 h, and declined to control levels at the end of the recovery period. Expression of GADD45 and p21 were both upregulated by 2-fold at 8 h, but declined to control levels during recovery. Neither the expression of p27 nor that of p16 were apparently affected by Cr(VI) exposure, however the expression of p15 was markedly increased after exposure to all concentrations of Cr(VI). Finally, the expression of cyclin A was decreased after 24 h Cr(VI) exposure. Cr(VI) induced a transient burst of ERK activity (2-6-fold over control) around 0.5-3 h after exposure. However, inhibition of ERK activation with PD98059 had no effect on the Cr-induced alterations in gene expression. Moreover, Cr(VI)-induced clonogenic lethality, as assessed after 24 h exposure to 1 and 2 uM Cr(VI), was also not affected by ERK inhibition. These data suggest that both p53-dependent and -independent apoptotic and growth-inhibitory pathways are markedly affected by Cr(VI) exposure. However, the ability of Cr(VI) to affect key apoptotic and growth arresting genes, and thus clonogenic lethality, appears to be independent of ERK. Continued investigation into the cellular and molecular mechanisms of Cr(VI)-induced cell cycle and apoptosis control should further the understanding of Cr(VI)-associated carcinogenesis.
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PMID:Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: lack of effect of ERK. 1497 55


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