Genetic studies and molecular cloning approaches have been successfully used to identify several transcription factors that regulate the numerous stages of cartilage development. Sex-determining region Y (SRY)-box 9 (Sox9) is an essential transcription factor for the initial stage of cartilage development. Sox5 and Sox6 play an important role in the chondrogenic action of Sox9, presumably by defining its cartilage specificity. Several transcription factors have been identified as transcriptional partners for Sox9 during cartilage development. Runt-related transcription factor 2 (Runx2) and Runx3 are necessary for hypertrophy of chondrocytes. CCAAT/enhancer-binding protein β (C/EBPβ) and activating transcription factor 4 (ATF4) function as co-activators for Runx2 during hypertrophy of chondrocytes. In addition, myocyte-enhancer factor 2C (Mef2C) is required for initiation of chondrocyte hypertrophy, presumably by functioning upstream of Runx2. Importantly, the pathogenic roles of several transcription factors in osteoarthritis have been demonstrated based on the similarity of pathological phenomena seen in osteoarthritis with chondrocyte hypertrophy. We discuss the importance of investigating cellular and molecular properties of articular chondrocytes and degradation mechanisms in osteoarthritis, one of the most common cartilage diseases.
Activating Transcription Factor 4 ; Cartilage Diseases ; Cartilage* ; Chondrocytes ; Cloning, Molecular ; Hypertrophy ; Osteoarthritis ; Sensitivity and Specificity ; Transcription Factors*

High glucose leads to physio/pathological alterations in diabetes patients. We investigated collagen production in human gingival cells that were cultured in high concentrations of glucose. Collagen synthesis and secretion were increased when the cells were exposed to high concentrations of glucose. We examined endoplasmic reticulum (ER) stress response because glucose metabolism is related to ER functional status. An ER stress response including the expression of glucose regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), inositol requiring enzyme alpha (IRE-1alpha) and phosphoreukaryotic initiation factor alpha (p-eIF-2alpha) was activated in the presence of high glucose. Activating transcription factor 4 (ATF-4), a downstream protein of p-eIF-2alpha as well as a transcription factor for collagen, was also phosphorylated and translocalized into the nucleus. The chemical chaperone 4-PBA inhibited the ER stress response and ATF-4 phosphorylation as well as nuclear translocation. Our results suggest that high concentrations of glucose-induced collagen are linked to ER stress and the associated phosphorylation and nuclear translocation of ATF-4.
Activating Transcription Factor 4 ; Butylamines ; Collagen ; Endoplasmic Reticulum ; Fibroblasts ; Glucose ; Humans ; Inositol ; Peptide Initiation Factors ; Phenylbutyrates ; Phosphorylation ; Transcription Factors

OBJECTIVE: To investigate whether Blimp1 plays an anti-apoptosis role in myeloma by interfering with ATF4/CHOP cell apoptosis pathway induced by endoplasmic reticulum stress, and to explore the anti-myeloma mechanism of aspirin. METHODS: The bone marrow fluid of 40 newly diagnosed multiple myeloma patients without treatment and 30 control people with relatively normal bone marrow was collected. Flow cytometry was used to separated the normal and abnormal plasma cells, LV-Blimp1-RNAi (40051-2) recombinant lentivirus down-regulates the expression of Blimp-1 in U266 cell line and detected the changes of the expression of ATF4 and CHOP gene. U266 cells were stimulated by aspirin at different concentrations (0, 0.5, 2.5, 5.0 mmol/L) in vitro. Then the effect of aspirin on proliferation of U266 cells was measured by CCK-8 assay, the mRNA expression levels of Blimp1, ATF4 and CHOP in four groups were detected by real-time PCR. RESULTS: The expression level of Blimp1 in phenotype abnormal plasma cells was significantly increased as compared with normal cells, while the expression of ATF4 and CHOP in phenotype abnormal plasma cells was significantly decreased as compared with normal cells (P＜0.05). In the case of MOI=100, the transfection efficiency of U266 cells was beyond 80% as detected by fluorescence microscopy. Compared with blank conrol and negatine control groups, Blimp1 mRNA expression level in positive group was significantly reduced while ATF4 and CHOP expression significantly increased. CCK-8 showed that the proliferation activity of U266 cells could be inhibited by aspirin, which showed a time-and dose-dependent manner; at the same time, the expression level of Blimp1 in U266 cells were decreased with the increasing of aspirin concentration, while the expression level of ATF4 and CHOP was increased with the increasing of aspirin concentration. CONCLUSIONS Blimp1 may display the anti-apoptosis of myeloma cells through interfering with ATF4/CHOP signaling pathway; low dose of aspirin may play anti-myeloma effect by inhibiting the expression of Blimp1 in myeloma cells.
Activating Transcription Factor 4 ; Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Humans ; Multiple Myeloma ; Positive Regulatory Domain I-Binding Factor 1 ; Signal Transduction

Up-frameshift 1 (UPF1), as the most critical factor in nonsense-mediated messenger RNA (mRNA) decay (NMD), regulates tumor-associated molecular pathways in many cancers. However, the role of UPF1 in lung adenocarcinoma (LUAD) amino acid metabolism remains largely unknown. In this study, we found that UPF1 was significantly correlated with a portion of amino acid metabolic pathways in LUAD by integrating bioinformatics and metabolomics. We further confirmed that UPF1 knockdown inhibited activating transcription factor 4 (ATF4) and Ser51 phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), the core proteins in amino acid metabolism reprogramming. In addition, UPF1 promotes cell proliferation by increasing the amino-acid levels of LUAD cells, which depends on the function of ATF4. Clinically, UPF1 mRNA expression is abnormal in LUAD tissues, and higher expression of UPF1 and ATF4 was significantly correlated with poor overall survival (OS) in LUAD patients. Our findings reveal that UPF1 is a potential regulator of tumor-associated amino acid metabolism and may be a therapeutic target for LUAD.
Activating Transcription Factor 4/genetics* ; Adenocarcinoma of Lung ; Amino Acids ; Cell Proliferation ; Eukaryotic Initiation Factor-2 ; Humans ; Lung Neoplasms ; RNA Helicases/metabolism* ; RNA, Messenger/metabolism* ; Trans-Activators/metabolism*

Cyclooxygenase-2 (COX-2) is an enzyme induced by various proinflammatory and mitogenic stimuli. Celecoxib is a selective inhibitor of COX-2 that have been shown to affect cell growth and apoptosis. Lung cancer cells expressing COX-2 is able to be a target of celecoxib, this study focuses on investigating that celecoxib induces apoptosis via endoplasmic reticulum (ER) stress on lung cancer cells. We investigated whether celecoxib induced apoptosis on non-small cell lung cancer cell line, A549 and H460. The 50 µM of celecoxib increased apoptotic cells and 100 µM of celecoxib significantly induced apoptosis. To check involvement of caspase cascade, pretreatment of z-VAD-fmk blocked celecoxib-induced apoptosis. However, caspase-3, -8, and -9 were not activated, but cleavage of non-classical caspase-4 was detected using western blot. As checking ER stress associated molecules, celecoxib did not increase expressions of growth arrest and DNA damage inducible protein 34, activating transcription factor 4, and spliced X-box binding protiens-1, but increase of both glucose-regulated protein 78 (GRP78) and C/EBP homologous transcription factor were detected. Salubrinal, inhibitor of eIF2 and siRNA for IRE1 did not alter celecoxib-induced apoptosis. Instead, celecoxib-induced apoptosis might be deeply associated with ER stress depending on GRP78 because siRNA for GRP78 enhanced apoptosis. Taken together, celecoxib triggered ER stress on lung cancer cells and celecoxib-induced apoptosis might be involved in both non-classical caspase-4 and GRP78.
Activating Transcription Factor 4 ; Apoptosis ; Blotting, Western ; Carcinoma, Non-Small-Cell Lung* ; Caspase 3 ; Celecoxib* ; Cell Death* ; Cell Line ; Cyclooxygenase 2 ; DNA Damage ; Endoplasmic Reticulum Stress* ; Endoplasmic Reticulum* ; Eukaryotic Initiation Factor-2 ; Lung Neoplasms ; RNA, Small Interfering ; Transcription Factors

The saturated free fatty acid (FFA), palmitate, could induce apoptosis in various cell types, but little is known about its effects on human umbilical cord-derived mesenchymal stem cells (hUC-MSCs). Here, we investigated whether palmitate induced apoptosis and endoplasmic reticulum (ER) stress in hUC-MSCs. hUC-MSCs were stained by labeled antibodies and identified by flow cytometry. After administration with palmitate, apoptotic cell was assessed by flow cytometry using the Annexin V-FITC/7-AAD apoptosis detection kit. Relative spliced XBP1 levels were analyzed using semi-quantitative RT-PCR. The mRNA of BiP, GRP94, ATF4 and CHOP were analyzed by real-time PCR. Relative BiP and CHOP protein were analyzed using Western blot analysis. The results showed that hUC-MSCs were homogeneously positive for MSC markers; palmitate increased apoptosis of hUC-MSCs and activated XBP1 splicing, BiP, GRP94, ATF4 and CHOP transcription. These findings suggest that palmitate induces apoptosis and ER stress in hUC-MSCs.
Activating Transcription Factor 4 ; metabolism ; Apoptosis ; DNA-Binding Proteins ; metabolism ; Endoplasmic Reticulum Stress ; Heat-Shock Proteins ; metabolism ; Humans ; Membrane Glycoproteins ; metabolism ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Palmitates ; pharmacology ; Regulatory Factor X Transcription Factors ; Transcription Factor CHOP ; metabolism ; Transcription Factors ; metabolism ; Umbilical Cord ; cytology ; X-Box Binding Protein 1

PURPOSE: Ischemic preconditioning (IPC), including remote IPC (rIPC) and direct IPC (dIPC), is a promising method to decrease ischemia-reperfusion (IR) injury. This study tested the effect of both rIPC and dIPC on the genes for antioxidant enzymes and endoplasmic reticulum (ER) stress-related proteins. MATERIALS AND METHODS: Twenty rats were randomly divided into the control and study groups. In the control group (n=10), the right hind limb was sham-operated. The left hind limb (IscR) of the control group underwent IR injury without IPC. In the study group (n=10), the right hind limb received IR injury after 3 cycles of rIPC. The IscR received IR injury after 3 cycles of dIPC. Gene expression was analyzed by Quantitative real-time polymerase chain reaction from the anterior tibialis muscle. RESULTS: The expression of the antioxidant enzyme genes including glutathione peroxidase (GPx), superoxide dismutase (SOD) 1 and catalase (CAT) were significantly reduced in IscR compared with sham treatment. In comparison with IscR, rIPC enhanced the expression of GPx, SOD2, and CAT genes. dIPC enhanced the expression of SOD2 and CAT genes. The expression of SOD2 genes was consistently higher in rIPC than in dIPC, but the difference was only significant for SOD2. The expression of genes for ER stress-related proteins tended to be reduced in IscR in comparison with sham treatment. However, the difference was only significant for C/EBP homologous protein (CHOP). In comparison with IscR, rIPC significantly up-regulated activating transcription factor 4 and CHOP, whereas dIPC up-regulated CHOP. CONCLUSION: Both rIPC and dIPC enhanced expression of genes for antioxidant enzymes and ER stress-related proteins.
Activating Transcription Factor 4 ; Animals ; Catalase ; Cats ; Endoplasmic Reticulum* ; Extremities ; Gene Expression ; Glutathione Peroxidase ; Ischemic Preconditioning* ; Methods ; Muscle, Skeletal* ; Placebos ; Rats* ; Real-Time Polymerase Chain Reaction ; Reperfusion Injury ; Superoxide Dismutase

BACKGROUND: Development of chemotherapeutics for the treatment of advanced hepatocellular carcinoma (HCC) has been lagging. Screening of candidate therapeutic agents by using patient-derived preclinical models may facilitate drug discovery for HCC patients. METHODS: Four primary cultured HCC cells from surgically resected tumor tissues and six HCC cell lines were used for high-throughput screening of 252 drugs from the Prestwick Chemical Library. The efficacy and mechanisms of action of the candidate anti-cancer drug were analyzed via cell viability, cell cycle assays, and western blotting. RESULTS: Guanabenz acetate, which has been used as an antihypertensive drug, was screened as a candidate anti-cancer agent for HCC through a drug sensitivity assay by using the primary cultured HCC cells and HCC cell lines. Guanabenz acetate reduced HCC cell viability through apoptosis and autophagy. This occurred via inhibition of growth arrest and DNA damage-inducible protein 34, increased phosphorylation of eukaryotic initiation factor 2α, increased activating transcription factor 4, and cell cycle arrest. CONCLUSIONS: Guanabenz acetate induces endoplasmic reticulum stress–related cell death in HCC and may be repositioned as an anti-cancer therapeutic agent for HCC patients.
Activating Transcription Factor 4 ; Apoptosis ; Autophagy ; Blotting, Western ; Carcinoma, Hepatocellular ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Death ; Cell Line ; Cell Survival ; DNA ; Drug Discovery ; Drug Repositioning ; Endoplasmic Reticulum ; Guanabenz ; Humans ; Mass Screening ; Peptide Initiation Factors ; Phosphorylation ; Primary Cell Culture

OBJECTIVETo investigate the role of transcription factor special AT-rich binding protein 2 (SATB2) in the osteoblasts differentiation of bone marrow stromal cells (BMSC) in vitro.

METHODSRats bone marrow stromal cells were isolated by Percoll sedimentation and the cells were placed and allowed to attach for three times. After passages, expression plasmid pBABE-hygro-satb2 was constructed, then transfected into BMSC. BMSCs were inoculated in conditioned medium and osteogenic factors were detected by western blotting and reverse transcription polymerase chain reaction (RT-PCR).

RESULTSThe morphological observation of BMSC showed either spindle or polygonal pattern. The cellular phenotypic marker of the third passage was CD29 positive and CD34 negative. The growth curve possessed "S" pattern. The intensity of calfilication in BMSC was higher in SATB2 transfection group (IA value 125974 ± 241) than that in the control groups (IA value 178486 ± 406). Moreover, cell migration rate increased in SATB2 transfection group [width of scratch (0.72 ± 0.01) mm] compared with control group [width of scratch (0.83 ± 0.03) mm]. In addition, the mRNA expression of osteogenic factors runt-related transcription factor 2, Osterix, activating transcription factor 4, integrin-binding sialoprotein were upregulated.

CONCLUSIONSCells cultured with this method have general biological characteristics and osteogenic differentiation potential in vitro. SATB2 can promote osteoblasts differentiation of BMSC.

Activating Transcription Factor 4 ; metabolism ; Animals ; Bone Marrow Cells ; metabolism ; pathology ; Cell Differentiation ; Cell Movement ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit ; metabolism ; Integrin-Binding Sialoprotein ; metabolism ; Male ; Matrix Attachment Region Binding Proteins ; genetics ; metabolism ; Osteoblasts ; cytology ; Osteogenesis ; Plasmids ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Stromal Cells ; metabolism ; pathology ; Thy-1 Antigens ; metabolism ; Transcription Factors ; genetics ; metabolism ; Transfection

OBJECTIVETo explore the intervention of baicalin on signal transduction and activating transcription factor expression of ulcerative colitis (UC) patients.

METHODSRecruited were UC patients at Outpatient Department of Digestive Disease, Inpatient Department of Digestive Disease, Center for Digestive Endoscopy of College City Branch, Guangdong Provincial Hospital of Traditional Chinese Medicine, and Southern Hospital affiliated to Southern Medical University from June 2010 to January 2011. They were assigned to the UC group (33 cases) and the diarrhea-predominant irritable bowel syndrome (IBS-D) group (30 cases). Another 30 healthy subjects were recruited as a healthy control group. Peripheral blood mononuclear cells (PBMCs) in vitro intervened by different concentrations baicalin were taken from UC patients. IL23R gene expressions in vitro intervened by different concentrations baicalin were detected using Q-PCR. Expressions of signal transducer and activator of transcription 4 (STAT4) , STAT6, phosphorylated-STAT4 (p-STAT4), and p-STAT6 were detected using Western blot. Serum levels of IFN-γ, IL-4, IL-6, and IL-10 were measured by ELISA. Effects of different concentrations baicalin on expressions of PBMCs, and levels of IFN-γ, IL-4, IL-10 of UC patients were also detected.

RESULTSCompared with the negative control group, 40 µmol baicalin obviously decreased IL23R gene expression of UC patients (P <0. 01). Compared with the healthy control group and the IBS-D group, p-STAT4/STAT4 ratios increased, p-STAT6/STAT6 ratios decreased, levels of IFN-γ, IL-4, IL-10 all increased in the US group (all P <0. 05). Compared with the negative control, 5 and 10 µmol baicalin groups, 20 and 40 moL baicalin obviously decreased p-STAT4/STAT4 ratios (all P <0. 05); 20 and 40 µmoL baicalin obviously increased p-STAT6/STAT6 ratios (all P <0. 05); 20 and 40 µmoL baicalin obviously lowered levels of IFN-γ and IL-4, and elevated IL-10 levels (all P <0. 05).

CONCLUSION40 µmoL baicalin could in vitro inhibit p-STAT4/STAT4 ratios, adjust p-STAT6/STAT6 ratios and related cytokines, thereby balancing the immunity and relieving inflammatory reactions of UC.

Activating Transcription Factors ; metabolism ; Anti-Inflammatory Agents, Non-Steroidal ; therapeutic use ; Blotting, Western ; Colitis, Ulcerative ; drug therapy ; metabolism ; Cytokines ; metabolism ; Flavonoids ; therapeutic use ; Humans ; Interleukin-10 ; metabolism ; Interleukin-4 ; metabolism ; Interleukin-6 ; metabolism ; Irritable Bowel Syndrome ; drug therapy ; metabolism ; Leukocytes, Mononuclear ; Medicine, Chinese Traditional ; Phosphorylation ; STAT6 Transcription Factor ; metabolism ; Signal Transduction