c-Jun, the most extensively studied protein of the activator protein-1 (AP-1) complex, is involved in numerous cell activities, such as proliferation, apoptosis, survival, tumorigenesis and tissue morphogenesis. Earlier studies focused on the structure and function have led to the identification of c-Jun as a basic leucine zipper (bZIP) transcription factor that acts as homo- or heterodimer, binding to DNA and regulating gene transcription. Later on, it was shown that extracellular signals can induce post-translational modifications of c-Jun, resulting in altered transcriptional activity and target gene expression. More recent work has uncovered multiple layers of a complex regulatory scheme in which c-Jun is able to crosstalk, amplify and integrate different signals for tissue development and disease. One example of such scheme is the autocrine amplification loop, in which signal-induced AP-1 activates the c-Jun gene promoter, while increased c-Jun expression feedbacks to potentiate AP-1 activity. Another example of such scheme, based on recent characterization of gene knockout mice, is that c-Jun integrates signals of several developmental pathways, including EGFR-ERK, EGFR-RhoA-ROCK, and activin B-MAP3K1-JNK for embryonic eyelid closure. After more than two decades of extensive research, c-Jun remains at the center stage of a molecular network with mysterious functional properties, some of which are yet to be discovered. In this article, we will provide a brief historical overview of studies on c-Jun regulation and function, and use eyelid development as an example to illustrate the complexity of c-Jun crosstalking with signaling pathways.
Animals ; Humans ; Mice ; Proto-Oncogene Proteins c-jun ; genetics ; metabolism ; Signal Transduction

OBJECTIVETo study the effect of selenium (Se) and iodine (I) and the compound of both on the proto-oncogenes c-fos and c-jun mRNA and their protein expression in the cultured rat hippocampus neurons.

METHODSUsing the technique of serum free hippocampus neuron culture, different doses of Se and I and Se + I compound were added into the medium. The expression of the mRNA of c-fos, c-jun in hippocampus neurons cultured for 1, 3, 5, 7 and 10 d were studied using both in situ hybridization and SABC immunohistochemical technique.

RESULTSBoth Se and I could enhance the expression of c-fos, c-jun mRNA and their proteins, especially the combination of I and Se able to give a remarkable effect on c-jun mRNA expression.

CONCLUSIONSSe and I may effect the expression of both c-fos and c-jun mRNA, especially the c-jun mRNA and its protein of hippocampus neurons, and thus may effect the differentiation and development of neurons.

Animals ; DNA-Binding Proteins ; metabolism ; Hippocampus ; metabolism ; Iodine ; Neurons ; metabolism ; Proto-Oncogene Proteins c-fos ; metabolism ; Proto-Oncogene Proteins c-jun ; metabolism ; RNA, Messenger ; metabolism ; Rats ; Selenium

OBJECTIVETo observe activating protein-1 (AP- 1) members in response to changes of wall-shear stress in osteoblastic cells in vitro.

METHODSIsolated and purified osteoblastic cells from the calvaria of newborn SD rats were cultured and subcultured. The third generation cells were subjected to wall-shear stress of 0.8 Pa, 1.2 Pa, 1.4 Pa and 1.6 Pa separately. Gene expression of the seven AP-1 members were studied before (0 h) and 10 min, 15 min, 30 min, 60 min after treated with wall-shear stress.

RESULTSThe expression of FosB, c-Fos, c-Jun, JunD and JunB mRNA increased transiently after application of 1.2 Pa wall-shear stress in osteoblastic cells compared to 0.8 Pa , 1.4 Pa and 1.6 Pa stress, and peaked at 15 min.

CONCLUSIONMechanical environment changes in osteoblastic cells induced a dramatic induction of most of the AP-1 members.

Animals ; Proto-Oncogene Proteins c-fos ; Proto-Oncogene Proteins c-jun ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Stress, Mechanical ; Transcription Factor AP-1

BACKGROUNDA 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.

METHODSThe 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.

RESULTSAfter 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).

CONCLUSIONSThese 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.

Animals ; Male ; Maze Learning ; Memory ; Neostriatum ; metabolism ; Proto-Oncogene Proteins c-fos ; biosynthesis ; Proto-Oncogene Proteins c-jun ; biosynthesis ; Rats ; Rats, Sprague-Dawley

Apoptosis ; Cell Cycle ; Cell Differentiation ; Cell Proliferation ; Humans ; Neoplastic Processes ; Proto-Oncogene Proteins c-jun ; genetics ; metabolism ; physiology

OBJECTIVE: To study the effect of forsythiaside on the expression of c-jun induced by cisplatin in the cochlea of guinea pig. METHOD: Thirty guinea pigs were randomly divided into control group (10), cisplatin group (10) and forsythiaside group (10). The ototoxicity model was done with intraperitoneal injection of cisplatin solution (8 mg/kg per day) for 7 days. Forsythiaside (25 mg/kg per day) was injected 30 min before cisplatin solution treated in guinea pigs of forsythiaside group for 7 consecutive days. The saline instead of cisplatin was injected in normal control group. The distortion product otoacoustic emission (DPOAE) was detected before animals were killed. The expression of c-jun in cochlea of guinea pigs was detected by western blotting. The expression of c-jun mRNA in cochlea of guinea pigs was detected by reverse transcriptase polymerase chain reaction (RT-PCR). RESULT: DPOAE amplitudes in cisplatin group was significantly lower than in control group (P < 0.01). Compared with cisplatin group, DPOAE amplitudes in forsythiaside group was increased significantly (P < 0.05). The expression of c-jun protein and mRNA were significantly increased in cisplatin group than in control group (P < 0.01). Compared with cisplatin group, the expression of c-jun protein and mRNA were significantly decreased in forsythiaside group. CONCLUSION Forsythiaside can significantly reduce the side effects induced by cisplatin through down-regulating the expression of c-jun.
Animals ; Cisplatin ; toxicity ; Cochlea ; drug effects ; metabolism ; Female ; Glycosides ; pharmacology ; Guinea Pigs ; Male ; Proto-Oncogene Proteins c-jun ; metabolism

OBJECTIVETo study the effects of VAC on starting the process of wound healing and decreasing apoptosis.

METHODSTo examine the variations in expression of proto-oncogenes c-myc, c-jun and Bcl-2 in pig wound model with acute full-thickness skin defect and human chronic wounds by immunohistochemistry, calculate the numbers of expressive positive cells and the labelling index (LI), and observe the process of wound healing.

RESULTS(1) In pig experiment, the wound in experimental group was very clean and without obvious exudates, many neoepiderm and granulation tissue rapidly appeared or formed after 6 days, and healed completely by the 25th day. On the contrary, in the wound of control group, more exudates and blood crust could be seen and fewer neoepiderm and granulation tissue appeared after 6 days and was healed by 30th day. Immediately after the wound was created, the expression of c-myc, c-jun and Bcl-2 was lower and mainly situated in nucleus or cytoplasma of the basilar cells. After the wound was created in control group, or after starting the VAC treatment in experimental group, their expression rapidly and obviously increased, the distribution of the positive cells also became enlarged, but the amount of expression decreased rapidly after the expressive peak have reached. In the successive 12 days following the wound was created, the expression of c-myc, c-jun and Bcl-2 in the experimental group was constantly higher than that of the control group. (2) In human chronic wounds, there wasn't obvious secretions and more healthy granulation tissue was rapidly formed after VAC treatment. The expression of c-jun was mainly located in cytoplasma of basilar cells of epithelium, dermal fibroblasts and inflammatory cells, and the positive cell and labelling index obviously decreased. The expression of c-myc and Bcl-2 was mainly in cytoplasma of basilar cells, but the amount of expression and the labelling index became obviously increased after VAC treatment.

CONCLUSIONSVAC could rapidly start the healing course of the pig' s acute skin wound and human chronic wound, decrease apoptosis of the reparative cells, so as to accelerate wound healing.

Adult ; Animals ; Apoptosis ; Female ; Humans ; Male ; Middle Aged ; Negative-Pressure Wound Therapy ; Proto-Oncogene Proteins c-jun ; metabolism ; Proto-Oncogenes ; Swine ; Wound Healing

OBJECTIVETo explore the DNA damage and the expression of oncogenic protein induced by cadmium in vitro (human cells) and in vivo in rats.

METHODSThe colony formation assay and the MTT assay were employed to determine the cytotoxicity of cadmium. The DNA damage and the cell cycle were measured by the comet assay and the flow cytometry, respectively. The western bolt and the X-Gal staining were also used to determine the change of oncogenic protein and the senescent marker.

RESULTSThe cadmium inhibited the proliferation of cells and induced DNA damage significantly not only in human cultured cells but also in vivo animal cells. The comet rate increased from 6.1% in the control group to 23.2% in 200 microM cadmium treatment group (P < 0.01). The comet rate increased in all organs of male rats with the increase of dosage, and there were significant difference between treatment the groups and the control group in kidney and ventral prostate (P < 0.05). Furthermore, the cadmium blocked the cell cycle progression. At the same time, the expression of c-myc, c-Jun and beta-Gal were increased by cadmium.

CONCLUSIONThe cadmium could induce DNA damage and block the cell cycle, and further cause senescence, and death. However, the cadmium induced the DNA damage and the oncogenic protein expression may be the important factors to cause cancer.

Animals ; Cadmium ; toxicity ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Comet Assay ; DNA ; drug effects ; DNA Damage ; Dose-Response Relationship, Drug ; Male ; Proto-Oncogene Proteins c-fos ; biosynthesis ; Proto-Oncogene Proteins c-jun ; biosynthesis ; Rats ; Rats, Wistar

OBJECTIVETo investigate effect of AP-1 and Ets binding site adjacent to matrix metalloproteinase-9 (MMP-9) promoter on activation of MMP-9 transcription of nasopharyngeal carcinoma cells transfected with EBV-encoded latent membrane protein 1 (LMP1), and to ascertain if cross-talk between c-Jun and Ets1 is involved in LMP1-regulating expression of MMP-9.

METHODSSite-directed mutagenesis technique was used to establish a series of mutants, including MMP-9-CAT-Ets(-540)mt, MMP-9-CAT-AP-1(-533)mt and MMP-9-CAT-AP-1(-533)/Ets(-540)mt. After the mutants were transfected into LMP1-expressing NPC HNE2 cells regulated by Tet-on system (pTet-on-LMP1 HNE2), CAT activity of these mutants were assayed with induction of LMP1. With blockade of c-Jun or Ets1 antisense oligonucleotides, the activity of MMP-9 induced by LMP1 was assayed with gelatin zymography.

RESULTSThe CAT activity of MMP-9-Ets(-540)mt-CAT, MMP-9-AP-1(-533)mt-CAT, MMP-9-AP-1(-533)/Ets(-540) mt-CAT decreased significantly compared to MMP-9-CAT wt. After blockade with c-Jun or Ets1 antisense oligonucleotides, activity of MMP-9 induced by LMP1 decreased significantly, especially with combined blockade of c-Jun and Ets1.

CONCLUSIONThe results suggest that transcription factor AP-1 and Ets play an crucial role in activation of MMP-9 transcription induced by LMP1, and cross-talk between c-Jun/Ets1 is involved in expression of MMP-9 mediated by LMP1.

Herpesvirus 4, Human ; genetics ; Humans ; Matrix Metalloproteinase 9 ; biosynthesis ; genetics ; Nasopharyngeal Neoplasms ; metabolism ; virology ; Proto-Oncogene Protein c-ets-1 ; genetics ; Proto-Oncogene Proteins c-jun ; genetics ; Transfection ; Tumor Cells, Cultured ; Viral Matrix Proteins ; genetics

The objective of this study was to investigate the changes of the behaviors, EEG and expression of c-fos, c-jun on induced seizure in rats by injecting penicillin after transmitting epileptic discharge from brain tissue to muscular tissue on skull. Eighteen experimental rats were divided into 3 groups, with each 6 rats. Seizure group: 6 acute seizure models were established by injecting penicillin in hippocampus of rats; Transferring group, 6 acute seizure models were established by injecting penicillin in hippocampus of rats, and electrode connected to muscles was planted into epileptic focus of each rat; Control group, 6 rats were only planted electrode in hippocampus without injecting penicillin. Then we observed the changes of behaviors, EEG and expression of C-fos, C-jun in hippocampus with immunohistochemical method. There was no statistic difference in seizure frequency of rat between seizure group and transferring group, but the discharging frequency in EEG of transferring group lowered significantly (P<0.05). The expression of C-fos, C-jun in hippocampus of transferring group rats was significantly lower than that of seizure group (P<0.005). It could be concluded that under the model of transmitting epileptic discharge from brain tissue to muscular tissue on skull, the burst times on EEG electrode decreased, concomitantly with the lower expression of C-fos, C-jun in hippocampus.
Animals ; Electrodes ; Electroencephalography ; Epilepsy ; chemically induced ; physiopathology ; Hippocampus ; metabolism ; Male ; Muscle, Skeletal ; physiopathology ; Penicillins ; Proto-Oncogene Proteins c-fos ; metabolism ; Proto-Oncogene Proteins c-jun ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley