Immediate-early Inducible Function in Upstream Region of junB Gene

Objective To analyze the upstream region of radiation-induced junB gene. Methods Four plasmids containing 250 bp, 590 bp, 900 bp and 1650 bp, and CAT reporter gene were constructed separately and introduced to L8704 cells. The cells were irradiated with 2 Gy X-rays and incubated at different intervals. Total RNA was extracted from the cells and fluctuation of the CAT mRNA level was assessed by the RNA ratio of CAT/β-actin measured by quantitative Northern blot hybridization. Results CAT mRNA expression containing 900 bp and 1560 bpjunB promoter remarkably and rapidly increased, and reached its peak 30min after 2 Gy X-my irradiation. Conclusions 590-900 bp fragments located in the upstream region of junB gene play an important role in the early process of cells against radiation.

Biological Analysis of HSV-1 Immediate-early Proteins ICP0, ICP22, and ICP27 in Neuroblastoma Cells

The three immediate-early proteins of HSV-1, ICP0, ICP22, and ICP27, have specific and pivotal functions in transcriptional activation and inhibition, multiple regulatory and control processes of viral genes. In this paper, the expression and localization of these three proteins were studied in neuroblastoma cells using biochemical assays, and their possible and potential interactive functions are discussed. The data show that the three proteins are localized in different structures, specifically in the PML-NB-associated structure, which is a specific nuclear structure composed of many protein molecules and bound tightly to the nuclear matrix in neuroblastoma cells. The results suggest that the activating and suppressive functions of ICPs are mostly dependent on their transcriptional and regulatory roles, including the PML-NB-associated structure.

Analysis of HSV-I ICP22 effects on HCMV major immediate-early promoter structure

The human cytomegalovirus (HCMV) major immediate-early (MIE) promoter has strong transcriptional promoting capability. Its cis-acting regulatory elements form a special structure in this region that is repeated multiple times; the biological significance of these elements and their different compositions in the transcriptional promoting process remain unclear. Our results demonstrate that the HSV-I MIE protein ICP22 can generate strong repression of many viral and cellular promoters and enhancers. We further studied the transcriptional effects of ICP22 on structural elements and mutations in various HCMV MIE promoters by using a CAT assay. In spite of different transcriptional effects of all the ele- ments in the presence of ICP22, the transcriptional efficiencies exhibited by mutations generated by different compositions and an entire HCMV promoter, are not the simple sum of the functions of these elements. Furthermore, the transcriptional activities of specific sequences were not affected by the presence of ICP22. Therefore, it is assumed that the HCMV MIE promoter co-regulates expression of downstream genes by using viral and cellular specific factors via a specific pathway.

Drosophila Ortholog of Mammalian Immediate-Early Gene Npas4 is Specifically Responsive to Reversal Learning

Dear Editor,In dynamic environments,the memory system of the brain must be able to perceive and process conflicting experiences to reach an adaptive decision.In Drosophila,in contrast to consistent experiences,conflicting experiences trigger significantly increased Rac1 activity which mediates active forgetting [1].The ability to cope with conflicting experiences but not simple learning experiences is impaired in mutants of multiple autism-risk genes [2].

Transcription factor EGR-1 inhibits growth of hepatocellular carcinoma and esophageal carcinoma cell lines

AIM: The transcription factor EGR-1 (early growth response gene-1) plays an important role in cell growth, differentiation and development. It has identified that EGR-1 has significant transformation suppression activity in some neoplasms, such as fibrosarcoma, breast carcinoma. This experiment was designed to investigate the role of egr-1 in the cancerous process of hepatocellular carcinoma (HCC) and esophageal carcinoma (EC), and then to appraise the effects of EGR-1 on the growth of these tumor cells. METHODS: Firstly, the transcription and expression of egr-1 in HCC and EC, paracancerous tissues and their normal counterpart parts were detected by in situ hybridization and immunohistochemistry, with normal human breast and mouse brain tissues as positive controls. Egr-1 gene was then transfected into HCC (HHCC, SMMC7721) and EC (ECa109) cell lines in which no egr-1 transcription and expression were present. The cell growth speed, FCM cell cycle, plate clone formation and tumorigenicity in nude mice were observed and the controls were the cell lines transfected with vector only. RESULTS: Little or no egr-1 transcription and expression were detected in HCC, EC and normal liver tissues. The expression of egr-1 were found higher in hepatocellular paracancerous tissue (transcription level P=0.000; expression level P=0.143, probably because fewer in number of cases) and dysplastic tissue of esophageal cancer (transcription level P=0.000; expression level P=0.001). The growth rate of egr-1-transfected HHCC (HCC cell line) cells and ECa109 (EC cell line) cells was much slower than that of the controls. The proportion of S phase cell, clone formation and tumorigenicity were significantly lower than these of the controls' (decreased 45.5% in HHCC cells and 34.1% in ECa109 cells; 46.6% and 41.8%; 80.4% and 72.6% respectively). There were no obvious differences between SMMC7721 (HCC) egr-1-transfected cells and the controls with regard to the above items. CONCLUSION: The decreased expression of egr-1 might play a role in the dysregulation of normal growth in the cancerous process of HCC and EC. Egr-1 gene of transfected HHCC and ECa109 cells showed obvious suppression of the cell growth and malignant phenotypes, but no suppression in SMMC7721 (HCC cell line) cells.

Experimental and clinic-opathologic study on the relationship between transcription factor Egr-1 and esophageal carcinoma

AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore the potential application of Egr-1 gene in gene therapy of tumor. METHODS: Eukaryotic expression vector of PCMV-Egr-1 plasmid was introduced into Eca109 cell line which expressed no Egr-1 protein originally with lipofectamine transfection method. The introduction and expression of PCMV-Egr-1 plasmid into Eca109 cell line was confirmed by G418 selection culture, PCR amplification of neogene contained in the vector, Western blot analysis and immunocytochemical analysis. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous Egr-1 gene on Eca109 cell line. The Egr-1 mRNA and Egr-1 protein were also detected in 50 surgical specimens of esophageal carcinoma by in situ hybridization and immunohistochemistry. RESULTS: Exogenous Egr-1 gene was introduced successfully into Eca109 cell line and expressed Egr-1 protein stably. The transfected Eca109 cell line grew more slowly than control Eca109 as shown by cell growth curves, the soft agar colony formation rate (4.0% vs 6.9%, P 【 0.01) and the average growth rate of tumor in SCID mice (35.5 +/- 7.6 vs 65.8 +/- 7.6, P 【 0.05). The expression level of Egr-1 mRNA and protein significantly increased in dysplastic epithelia adjacent to cancer rather than in cancer tissues (65.8% vs 20.0% by ISH and 57.9% vs 0.01). CONCLUSION: Exogenous Egr-1 gene shows the strong effect of growth inhibition in Eca109 cell line. Egr-1 in the cancer tissue shows down-regulated expression that supports the inhibited function of Egr-1 in cancer growth and suggests Egr-1 may have an important role in gene therapy of esophageal carcinoma.

The Role, Mechanism and Transcriptional Regulation of LAT in Herpes Simplex Virus Latency and Reactivation

Herpes simplex virus (HSV) infection in the human body can be latent in neurons for long time and be reactivated leading to recurrence at high rate. Currently there is no effective clinical strategy for the prevention and treatment of the disease relapse. HSV LAT gene is expressed in large quantities and lytic genes are turned off leading to HSV latency. Disruption of the gene expression is thought to cause HSV reactivation and disease relapse. To reveal the essence of HSV latency and reactivation, we summarized and innovatively classified the role, mechanism and transcriptional regulation of LAT in HSV latency and reactivation. This review may have important implications for future studies on HSV latency and reactivation, HSV disease prevention and treatment, and safer and more effective oncolytic HSVs (oHSVs).

Illuminating the Activated Brain: Emerging Activity-Dependent Tools to Capture and Control Functional Neural Circuits

Immediate-early genes(IEGs) have long been used to visualize neural activations induced by sensory and behavioral stimuli. Recent advances in imaging techniques have made it possible to use endogenous IEG signals to visualize and discriminate neural ensembles activated by multiple stimuli, and to map whole-brain-scale neural activation at single-neuron resolution. In addition, a collection of IEG-dependent molecular tools has been developed that can be used to complement the labeling of endogenous IEG genes and, especially, to manipulate activated neural ensembles in order to reveal the circuits and mechanisms underlying different behaviors. Here, we review these techniques and tools in terms of their utility in studying functional neural circuits. In addition, we provide an experimental strategy to measure the signal-to-noise ratio of IEG-dependent molecular tools, for evaluating their suitability for investigating relevant circuits and behaviors.

Expression of c-fos and c-jun proteins in the marginal division of the rat striatum during learning and memory training

Background A new brain region, the marginal division (MrD), was discovered at the caudal margin of the neostriatum. The MrD was shown to be involved in learning and memory in the rat. The aim of this study was to investigate the expression of the immediate-early genes c-fos and c-jun in the MrD of the striatum during learning and memory processes in the rat, immunocytochemical and Western blot methods were used to examine Y-maze trained rats.Methods The rats were divided into three groups, namely the training, pseudotraining, and control groups. After Y-maze training, the expression of the immediate-early genes c-fos and c-jun in the MrD of the rats was investigated using immunocytochemical and Western blot methods. Results After one hour of Y-maze training, the expression of c-jun and c-fos proteins was significantly enhanced in the MrD; the c-jun protein, in particular, was more intensely expressed in this region than in other parts of the striatum. The expression of these two proteins in the training group was significantly higher than in the pseudotraining and control groups. In addition, positive expression was also found in the hippocampus, cingulum cortex, thalamus, and in other areas. Western blot disclosed two immunoreactive bands for the anti-c-fos antibody (47 kD and 54 kD) and two immunoreactive bands for the anti-c-jun antibody (39 kD and (54 kD).) Conclusions These results indicate that the immediate-early genes c-fos and c-jun participate in signal transduction during the learning and memory processes associated with Y-maze training in rats.