BACKGROUNDCalreticulin (CRT) is major Ca 2+ -binding chaperone mainly resident in the endoplasmic reticulum (ER) lumen. Recently, it has been shown that non-ER CRT regulates a wide array of cellular responses. We previously found that CRT was up-regulated during hypoxia/reoxygenation (H/R) and this study was aimed to investigate whether CRT nuclear translocation aggravates ER stress (ERS)-associated apoptosis during H/R injury in neonatal rat cardiomyocytes.

METHODSApoptosis rate and lactate dehydrogenase (LDH) leakage in culture medium were measured as indices of cell injury. Immunofluorescence staining showed the morphological changes of ER and intracellular translocation of CRT. Western blotting or reverse transcription polymerase chain reaction was used to detect the expression of target molecules.

RESULTSCompared with control, H/R increased apoptosis rate and LDH activity. The ER became condensed and bubbled, and CRT translocated to the nucleus. Western blotting showed up-regulation of CRT, Nrf2, activating transcription factor 4 (ATF4), CHOP and caspase-12 expression after H/R. Exogenous CRT overexpression induced by plasmid transfection before H/R increased cell apoptosis, LDH leakage, ER disorder, CRT nuclear translocation and the expression of ERS-associated molecules. However, administration of the ERS inhibitor, taurine, or CRT siRNA alleviated cell injury, ER disorder, and inhibited ERS-associated apoptosis.

CONCLUSIONSOur results indicated that during H/R stress, CRT translocation increases cell apoptosis and LDH leakage, aggravates ER disorder, up-regulates expression of nuclear transcription factors, Nrf2 and ATF4, and activates ERS-associated apoptosis.

Animals ; Apoptosis ; genetics ; physiology ; Calreticulin ; genetics ; metabolism ; Cell Hypoxia ; genetics ; physiology ; Cell Survival ; genetics ; physiology ; Cells, Cultured ; Endoplasmic Reticulum Stress ; physiology ; Myocytes, Cardiac ; cytology ; metabolism ; RNA Interference ; Rats

LncRNA H19 encoded by the H19 imprinting gene plays an important regulatory role in the cell. Recently study has found that in hypoxic cells, the expression of H19 gene changes, and the transcription factors and protein involved in the expression change accordingly. Through the involvement of specific protein 1 (SP1), hypoxia-inducible factor-1α (HIF-1α) binds directly to the H19 promoter and induces the up-regulation of H19 expression under hypoxic conditions. The tumor suppressor protein p53 may also mediate the expression of the H19 gene, in part by interfering with HIF-la activity under hypoxia stress. The miR675-5p encoded by exon 1 of H19 promotes hypoxia response by driving the nuclear accumulation of HIF-1α and reducing the expression of VHL gene, which is a physiological HIF-1α inhibitor. In addition, under the condition of hypoxia, the expression of transporter on cell membrane changes, and the transition of the intracellular glucose metabolism pathway from aerobic oxidation to anaerobic glycolysis is also involved in the involvement of H19. Therefore, H19 may be a key gene that maintains intracellular balance under hypoxic conditions and drives adaptive cell survival under conditions of hypoxia stress.
Cell Hypoxia ; genetics ; Genes, Tumor Suppressor ; physiology ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; genetics ; RNA, Long Noncoding ; Up-Regulation ; physiology ; Von Hippel-Lindau Tumor Suppressor Protein ; genetics

Phenotypic transformation of pulmonary artery smooth muscle cells (PASMCs) is a key factor in pulmonary vascular remodeling. Inhibiting or reversing phenotypic transformation can inhibit pulmonary vascular remodeling and control the progression of hypoxic pulmonary hypertension. Recent studies have shown that hypoxia causes intracellular peroxide metabolism to induce oxidative stress, induces multi-pathway signal transduction, including those related to autophagy, endoplasmic reticulum stress and mitochondrial dysfunction, and also induces non-coding RNA regulation of cell marker protein expression, resulting in PASMCs phenotypic transformation. This article reviews recent research progress on mechanisms of hypoxia-induced phenotypic transformation of PASMCs, which may be helpful for finding targets to inhibit phenotypic transformation and to improve pulmonary vascular remodeling diseases such as hypoxia-induced pulmonary hypertension.
Humans ; Pulmonary Artery ; Hypertension, Pulmonary ; Vascular Remodeling/genetics* ; Hypoxia/genetics* ; Myocytes, Smooth Muscle ; Cell Proliferation/physiology* ; Cells, Cultured ; Cell Hypoxia/genetics*

OBJECTIVETo investigate whether hepatitis B x protein (HBx) stimulates vascular endothelial growth factor (VEGF) through hypoxia inducible factor-1 (HIF-1 alpha) pathway.

METHODSTwo plasmids including pIRES-EGFP-HBx and pTK-Hyg were co-transfected to a hepatocellular carcinoma cell line SMMC-7721. With fluorescence-positive and fluorescence-negative hygromycin-resistant colonies selected, expressions of VEGF and HIF-1 alpha in protein or/and mRNA level were detected.

RESULTSFluorescence-positive cells were stably integrated with HBx, in which expression of HIF-1 alpha and VEGF were upregulated. Fluorescence-negative cells did not express HBx, VEGF or HIF-1 alpha.

CONCLUSIONHBx can activate VEGF through HIF-1 alpha pathway.

Cell Line, Tumor ; Gene Expression Regulation ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; Trans-Activators ; physiology ; Transcription Factors ; genetics ; physiology ; Vascular Endothelial Growth Factor A ; genetics ; physiology

OBJECTIVETo investigate the role of long non-coding RNA (lncRNA) BC088414 in hypoxic-ischemic injury of neural cells.

METHODSRat adrenal pheochromocytoma (PC12) cells were divided into four groups: normoxic, oxygen glucose deprivation (OGD), siRNA-normoxic (siRNA group) and siRNA-OGD (n=3 each). Cells were incubated in glucose-free and serum-free DMEM medium under the conditions of 37℃ and 1% O2+99% N2/CO2 for 6 hours to establish an in vitro hypoxic-ischemic model. Quantitative real-time PCR was used to measure mRNA expression of lncRNA BC088414, β2-adrenoceptor (Adrb2), and caspase-6 (CASP6). siRNAs were used to inhibit BC088414 expression in PC12 cells. The TUNEL method was used to measure cell apoptosis.

RESULTSThe OGD group had a significantly higher cell apoptotic index than the normoxic group (P<0.01). After inhibition of BC088414 expression, the OGD group had a significantly reduced apoptotic index (P<0.05). The OGD group had significantly higher mRNA expression levels of lncRNA BC088414, Adrb2, and CASP6 compared with the normoxic group (P<0.05). The siRNA -normoxic group had significantly lower mRNA expression levels of Adrb2 and CASP6 than the normoxic group (P<0.05), and the siRNA-OGD group also had significantly lower mRNA expression levels of Adrb2 and CASP6 than the OGD group (P<0.05).

CONCLUSIONSLncRNA BC088414 may promote apoptosis through Adrb2 and CASP6 and aggravate neural cell injury induced by hypoxia-ischemia.

Animals ; Apoptosis ; Caspase 6 ; genetics ; physiology ; Cell Hypoxia ; Neurons ; pathology ; PC12 Cells ; RNA, Long Noncoding ; physiology ; RNA, Messenger ; analysis ; Rats ; Receptors, Adrenergic, beta-2 ; genetics ; physiology

Background: Microparticles (MPs) are small extracellular plasma membrane particles shed by activated and apoptotic cells, which are involved in the development of atherosclerosis. Our previous study found that microRNA (miR)-19b encapsulated within endothelial MPs (EMPs) may contribute to the upregulation of circulating miR-19b in unstable angina patients. Hypoxia is involved in atherosclerosis as a critical pathological stimulus. However, it still remains unclear whether the increase of miR-19b levels in EMPs is related to hypoxia and if the effect of miR-19b - wrapped within EMPs - stimulates hypoxia on vascular endothelial cells. This study aimed to explore the changes of miR-19b in EMPs induced by hypoxia as well as their effects on endothelial cells. Methods: Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and arranged to harvest EMPs in two parts: the first part consisted of EMP and EMP and the second part included EMP, EMP, and EMP. Cell migration was detected by scratch migration and transwell chamber migration. Angiogenesis was assessed by tube formation assays. Furthermore, we predicted the target gene of miR-19b by bioinformatics analysis, and luciferase assay was used to verify the targeted gene of miR-19b. Data were analyzed by one-way analysis of variance. Student's t-test was used when two groups were compared. Results: Compared with EMP- and EMP-inhibited migration of cells by scratch migration assay (80.77 ± 1.10 vs. 28.37 ± 1.40, P < 0. 001) and transwell chamber migration assay (83.00 ± 3.46 vs. 235.00 ± 16.52, P < 0.01), the number of tube formations was markedly reduced by 70% in the EMP group (P < 0.001) in vitro analysis of HUVECs. Meanwhile, a strong inhibition of migration and tube formation of HUVECs in the presence of miR-19b-enriched EMP was observed. This effect might be due to the delivery of miR-19b in EMPs. Transforming growth factor-β2 (TGFβ2) was predicted to be one of the target genes of miR-19b, and we further confirmed that TGFβ2 was a direct target gene of miR-19b using the luciferase assay. The expression of TGFβ2 in HUVECs was inhibited by treatment with EMP and EMP. Conclusions MiR-19b in EMPs induced by hypoxia could reduce endothelial cell migration and angiogenesis by downregulating TGFβ2 expression, which may have inhibited the progression of atherosclerosis.
Cell Hypoxia ; genetics ; physiology ; Cell Movement ; genetics ; physiology ; Endothelial Cells ; metabolism ; Human Umbilical Vein Endothelial Cells ; metabolism ; Humans ; MicroRNAs ; genetics ; metabolism ; Neovascularization, Physiologic ; genetics ; physiology ; Transforming Growth Factor beta2 ; genetics ; metabolism

Anemia ; metabolism ; physiopathology ; Animals ; Cell Hypoxia ; Genetic Therapy ; Humans ; Hypoxia-Inducible Factor 1 ; genetics ; metabolism ; physiology ; Neovascularization, Pathologic ; metabolism ; pathology ; Neovascularization, Physiologic ; Osteogenesis ; RNA, Messenger ; metabolism

OBJECTIVETo explore the role of HIF1α gene in prostate cancer cell line DU145 by knocking it out with a novel gene-editing tool CRISPR/cas9 system.

METHODSA CRISPR/cas9 system with two sgRNAs targeting exon 1 of the HIF1α gene was constructed for the knock out experiment. CCK8 assay and transwell experiment were carried out to assess the effect of the knock out on the proliferation, migration and invasiveness of DU145 cells.

RESULTSThe efficiency of gene-targeting was measured through a T7E1 assaying and sequence analysis, which confirmed that the partial knock out was successful and has led to a significant decrease in the expression of HIF1α and inhibition of cell proliferation, migration and invasiveness.

CONCLUSIONA CRISPR/cas9 system for the knock out of HIF1α has been successfully constructed, which could inhibit the proliferation and migration of DU145 cells. The system can facilitate further studies of the HIF1α gene and its roles in tumorigenesis.

CRISPR-Cas Systems ; genetics ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Gene Editing ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; genetics ; physiology ; Male ; Neoplasm Invasiveness ; Prostatic Neoplasms ; pathology

The effects of hypoxia on the level of reactive oxygen species (ROS), IkappaBalpha tyrosine phosphorylation, transcription of P65 mRNA and NF-kappaB activation in isolated rat peritoneal macrophages were investigated by DCFH-DA fluorescence spectrophotometry, Western blotting and RT-PCR. The results obtained are as follows. (1) During hypoxia, the levels of intracellular ROS began to increase at 1 h, then reached a peak at 2 h, and began to decrease after 3 h. IkappaBalpha tyrosine phosphorylation began to rise after 2 h hypoxia and was the highest after 3 h hypoxia. After 4 h hypoxia it decreased gradually. NF-kappaB activation began to increase after 3 h hypoxia, and reached a peak after 4 h hypoxia. (2) When antioxidant NAC (500 mmol/L) was added into the medium, the level of IkappaBalpha phosphorylation showed no significant changes during hypoxia. After adding protein tyrosine kinase inhibitor genistein (200 micromol/L), NF-kappaB activation induced by hypoxia was blocked significantly. (3) The expression of p65 mRNA was also elevated markedly during hypoxia. These results suggest that hypoxia may lead to IkappaBalpha phosphorylation and NF-kappaB activation through intracellular ROS, and that the regulation of NF-kappaB activity may involve IkappaBalpha phosphorylation and the expressions of each subunit gene of NF-kappaB.
Animals ; Cell Hypoxia ; Cells, Cultured ; Macrophages, Peritoneal ; cytology ; physiology ; Mice ; NF-kappa B ; biosynthesis ; genetics ; physiology ; Phosphorylation ; RNA, Messenger ; biosynthesis ; genetics ; Reactive Oxygen Species ; analysis ; Signal Transduction

BACKGROUNDOne effect of solid tumors is severe hypoxia of local tissues. Heme oxygenase-1 (HO-1) is highly expressed in a variety of human tumor tissues; its induction and activity are closely related to growth of solid tumors. Hypoxia inducible factor-1 (HIF-1) is a transcription factor that regulates hypoxia signal transduction and plays a central role in tumor hypoxia regulation. However, whether and how changes in HO-1 activity affect HIF-1 gene expression has not been reported previously.

METHODSHypoxia-inducible models were established using gastric cancer cell lines (SGC-7901) in a hypoxia incubator. Cells were placed in four groups: Group A, transfected by plasmid harboring HO-1 shRNA; Group B, transfected with scrambled shRNA vector; Group C, treated with hemin; and Group D, exposed to hypoxia only. Expressions of HO-1 and HIF-1 mRNAs were quantified by reverse transcription-polymerase chain reaction. Expressions of HO-1 and HIF-1 proteins were determined by immunohistochemistry and Western blotting.

RESULTSmRNA and protein levels of HO-1 and HIF-1 in the control group were significantly higher than in Group A (P < 0.01), but lower than in Group C (P < 0.01). Chromatin immunoprecipitation analysis showed that HIF-1 was identified as the direct HO-1 target gene.

CONCLUSIONWhile affected by HIF-1, HO-1 up-regulation promotes the expression of HIF-1 and the down-regulation of HO-1 suppresses the expression of HIF-1 gene.

Blotting, Western ; Cell Hypoxia ; genetics ; physiology ; Cell Line, Tumor ; Chromatin Immunoprecipitation ; Heme Oxygenase-1 ; genetics ; metabolism ; Humans ; Hypoxia-Inducible Factor 1 ; genetics ; metabolism ; Immunohistochemistry ; RNA, Small Interfering ; Reverse Transcriptase Polymerase Chain Reaction