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*

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

OBJECTIVE: To examine the expression of liver X receptor-β (LXR-β) in human gastric cancer tissue, and to explore the effect of GW3965, an agonist of LXRs, on proliferation of gastric cancer cell line SGC-7901.
 METHODS: The immunohistochemical assay was used to detect the expression of LXR-β, activating transcription factor 4 (ATF4) in gastric cancer tissues and the corresponding pericarcinoma tissues in 114 patients. Real-time quantitative PCR and Western blot were used to determine mRNA and protein levels of ATF4 and ATP-binding cassette 1 (ABCA1), one of the downstream target genes of LXRs, in SGC-7901 cells with or without GW3965 treatment. Cell counting kit-8 (CCK-8) assay was performed to detect cell proliferation. The expression of ATF4 was silenced by short hairpin RNA (shRNA).
 RESULTS: The expressions of LXR-β and ATF-4 were obviously down-regulated in the gastric cancer tissues than that in the corresponding pericarcinoma tissues (both P<0.05). Compared with the control cells, GW3965 treatment inhibited proliferation of SGC-7901 cells and up-regulated ATF4 and ABCA1 expressions (both P<0.05). Knockdown of ATF4 can reverse the antiproliferative effect of GW3965 on SGC-7901 cells.
 CONCLUSION The expression of LXR-β is decreased in human gastric cancer tissues, and activation of LXRs by GW3965 could inhibit the proliferation of SGC-7901 cells via ATF4.
Activating Transcription Factor 4 ; genetics ; metabolism ; Benzoates ; pharmacology ; Benzylamines ; pharmacology ; Cell Line, Tumor ; drug effects ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; Gene Silencing ; Humans ; Liver X Receptors ; Orphan Nuclear Receptors ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Stomach Neoplasms ; pathology ; Up-Regulation

When we treated rat bone marrow stromal cells (rBMSCs) with neuronal differentiation induction media, typical unfolded protein response (UPR) was observed. BIP/GRP78 protein expression was time-dependently increased, and three branches of UPR were all activated. ATF6 increased the transcription of XBP1 which was successfully spliced by IRE1. PERK was phosphorylated and it was followed by eIF2alpha phosphorylation. Transcription of two downstream targets of eIF2alpha, ATF4 and CHOP/GADD153, were transiently up-regulated with the peak level at 24 h. Immunocytochemical study showed clear coexpression of BIP and ATF4 with NeuN and Map2, respectively. UPR was also observed during the neuronal differentiation of mouse embryonic stem (mES) cells. Finally, chemical endoplasmic reticulum (ER) stress inducers, thapsigargin, tunicamycin, and brefeldin A, dose-dependently increased both mRNA and protein expressions of NF-L, and, its expression was specific to BIP-positive rBMSCs. Our results showing the induction of UPR during neuronal differentiations of rBMSCs and mES cells as well as NF-L expression by ER stress inducers strongly suggest the potential role of UPR in neuronal differentiation.
Activating Transcription Factor 4/genetics/metabolism ; Animals ; Apoptosis/drug effects ; Bone Marrow Cells/*cytology ; Cell Differentiation ; Culture Media/pharmacology ; Embryonic Stem Cells/*cytology ; Endoplasmic Reticulum/genetics/metabolism ; Gene Expression/drug effects ; Heat-Shock Proteins/*genetics/metabolism ; Mice ; Microtubule-Associated Proteins/genetics/metabolism ; Molecular Chaperones/*genetics/metabolism ; Nerve Tissue Proteins/genetics/*metabolism ; Neurofilament Proteins/genetics/metabolism ; Neurons/*cytology ; Nuclear Proteins/genetics/metabolism ; Protein Folding ; Rats ; Stromal Cells

OBJECTIVETo study the role of antenatal glucocorticoid (dexamethasone and betamethasone) on bone morphogenetic protein (BMP) signal transduction of the rat fetal lungs.

METHODSFifteen pregnant rats were randomly divided into five groups: the rats treated with dexamethasone for 1 day (1D-DEX) or 3 days (3D-DEX), with betamethasone for 1 day (1D-BEX) or 3 days (3D-BEX) or with normal saline (control group), followed cesarean section on the 19th day of gestation. The mRNA levels of BMP4, BMPR-II, Smad1 and ATF-2 of fetal rat lungs were ascertained by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of BMP4, BMPR-II, Smad1 and ATF-2 antigen expression in fetal lungs was assessed by immune histochemical staining. The expression of BMP4 and BMPR-II was determined by Western blot.

RESULTSThe levels of BMP4, BMPR-II and Smad1 mRNA expression were up-regulated in the 1D-BEX, 3D-BEX and 3D-DEX groups compared with those in the control group (P<0.05). The immune histochemiscal analysis showed that the expression of BMP4, BMPR-II, Phospho-Smad1 (pSmad1) and ATF-2 in the 1D-BEX, 3D-BEX and 3D-DEX groups was significantly higher than that in the control group (P<0.01). The results of Western blot demonstrated that the expression of BMP4 and BMPR-II protein increased significantly in the 1D-BEX, 3D-BEX and 3D-DEX groups when compared with the control group (P<0.01).

CONCLUSIONSBetamethasone and dexamethasone may play important roles in the regulation of BMP signal transduction in the rat fetal lungs. Up-regulation of BMP4, BMPR-II and Smad1 might be one of crucial factors for the glucocorticoid-induced maturity of fetal lungs.

Activating Transcription Factor 2 ; analysis ; genetics ; Animals ; Betamethasone ; pharmacology ; Bone Morphogenetic Protein 4 ; analysis ; genetics ; physiology ; Bone Morphogenetic Protein Receptors, Type II ; analysis ; genetics ; Dexamethasone ; pharmacology ; Female ; Fetus ; drug effects ; metabolism ; Lung ; drug effects ; metabolism ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; drug effects ; Smad1 Protein ; analysis ; genetics

Serum palmitic acid (PA), a type of saturated fatty acid, causes lipid accumulation and induces toxicity in hepatocytes. Ethanol (EtOH) is metabolized by the liver and induces hepatic injury and inflammation. Herein, we analyzed the effects of EtOH on PA-induced lipotoxicity in the liver. Our results indicated that EtOH aggravated PA-induced apoptosis and lipid accumulation in primary rat hepatocytes in dose-dependent manner. EtOH intensified PA-caused endoplasmic reticulum (ER) stress response in vitro and in vivo, and the expressions of CHOP, ATF4, and XBP-1 in nucleus were significantly increased. EtOH also increased PA-caused cleaved caspase-3 in cytoplasm. In wild type and CHOP(-/-) mice treated with EtOH and high fat diet (HFD), EtOH worsened the HFD-induced liver injury and dyslipidemia, while CHOP knockout blocked toxic effects of EtOH and PA. Our study suggested that targeting UPR-signaling pathways is a promising, novel approach to reducing EtOH and saturated fatty acid-induced metabolic complications.
Activating Transcription Factor 4 ; drug effects ; metabolism ; Animals ; Apoptosis ; drug effects ; Caspase 3 ; drug effects ; Chemical and Drug Induced Liver Injury ; metabolism ; DNA-Binding Proteins ; drug effects ; metabolism ; Diet, High-Fat ; adverse effects ; Dose-Response Relationship, Drug ; Dyslipidemias ; chemically induced ; metabolism ; Endoplasmic Reticulum Stress ; drug effects ; Ethanol ; metabolism ; toxicity ; Fatty Liver ; chemically induced ; metabolism ; Gene Knockout Techniques ; Hepatocytes ; drug effects ; metabolism ; Lipid Metabolism ; drug effects ; Liver ; metabolism ; Male ; Mice ; Palmitic Acid ; toxicity ; Rats ; Rats, Sprague-Dawley ; Regulatory Factor X Transcription Factors ; Signal Transduction ; drug effects ; Transcription Factor CHOP ; drug effects ; genetics ; metabolism ; Transcription Factors ; drug effects ; metabolism ; Unfolded Protein Response ; drug effects ; X-Box Binding Protein 1