Glucocorticoid receptor regulates expression of microRNA-22 and downstream signaling pathway in apoptosis of pancreatic acinar cells.

AIM: To elucidate the underlying mechanism that microRNA-22 (miR-22) promotes the apoptosis of rat pancreatic acinar cells (AR42J) and the elements that regulate the expression of miR-22. METHODS: One hundred nanomoles per liter of caerulein (Cae) was administrated to induce the apoptosis of AR42J cells and the apoptosis rate was detected by flow cytometry analysis. An amylase assay kit was used to measure the amylase expression level in the supernatant. Quantitative real-time PCR (qRT-PCR) was adopted to measure miR-22 expression. We used online tools to predict the potential transcription promoter of miR-22 and the binding sites, which was further identified by using luciferase reporter analysis, chromatin immunoprecipitation (ChIP) and ChIP-qPCR assays. Then, a mimic of miR-22, Nr3c1 plasmid encoding the glucocorticoid receptor (GR), and si-Nr3c1 were used to transfect AR42J cells, respectively. The mRNA expression of miR-22, Nr3c1, and Erb-b2 receptor tyrosine kinase 3 (ErbB3) was confirmed by qRT-PCR and the apoptosis rate of AR42J cells was detected by flow cytometry analysis. Western blot was used to detect the expression of ErbB3, GR, PI3k, PI3k-p85α, Akt, p-Akt, Bad, Bax, Bcl-xl, Bcl-2, and cleaved caspase3. RESULTS: After inducing apoptosis of AR42J cells in vitro, the expression of miR-22 was significantly increased by 2.20 ± 0.26 and 4.19 ± 0.54 times, respectively, at 3 h and 6 h in comparison with the control group. As revealed by qRT-PCR assay, the expression of miR-22 was 78.25 ± 6.61 times higher in the miR-22 mimic group relative to the miRNA control group, accompanied with an obviously increased acinar cell apoptosis rate (32.53 ± 1.15 vs 18.07 ± 0.89, P = 0.0006). The upregulation of miR-22 could suppress its target gene, ErbB3, and the phosphorylation of PI3k and Akt. Furthermore, we predicted the potential transcription promoter of miR-22 and the binding sites using online tools. Luciferase reporter analysis and site-directed mutagenesis indicated that the binding site (GACAGCCATGTACA) of the GR, which is encoded by the Nr3c1 gene. Downregulation of the expression of GR could upregulate the expression of miR-22, which further promoted the apoptosis of AR42J cells. CONCLUSION: GR transcriptionally represses the expression of miR-22, which further promotes the apoptosis of pancreatic acinar cells by downregulating the downstream signaling pathway.

Single-Cell Non-coding RNA in Embryonic Development.

Non-coding RNAs (ncRNAs) have significant regulatory functions on the regulation of gene expression of various life activities after transcription, even though they do not encode proteins. During the development of embryos, ncRNAs, such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs), circular RNAs (circRNAs), small nucleolar RNAs (snoRNAs), and Piwi-interacting RNAs (piRNAs), have been widely proven as key regulators. The emerging single-cell RNA sequencing technique is powerful for profiling "cell-to-cell" variability at the genomic level. It has been applied to detect the expression of ncRNAs during embryo development. In this chapter, we pay close attention to single-cell ncRNA expression and summarize their roles in embryo development.

miR-29a up-regulation in AR42J cells contributes to apoptosis via targeting TNFRSF1A gene.

AIM: To investigate the expression of miR-29a in rat acute pancreatitis and its functional role in AR42J cell apoptosis. METHODS: Twelve SD rats were divided into a control group and an acute edematous pancreatitis (AEP) group randomly. AEP was induced by intraperitoneal injection of L-arginine (150 mg/kg) in the AEP group and equal volume of 0.9% NaCl was injected in the control group. The apoptosis of acinar cells in pancreatic tissue was determined by TUNEL assay. miRNA chip assay was performed to examine the expression of miRNAs in two groups. Besides, to further explore the role of miR-29a in apoptosis in vitro, recombinant rat TNF-α (50 ng/mL) was administered to treat the rat pancreatic acinar cell line AR42J for inducing AR42J cell apoptosis. Quantitative real-time PCR (qRT-PCR) was adopted to measure miR-29a expression. Then, miRNA mimic, miRNA antisense oligonucleotide (AMO) and control vector were used to transfect AR42J cells. The expression of miR-29a was confirmed by qRT-PCR and the apoptosis rate of AR42J cells was detected by flow cytometry analysis. Western blot was used to detect the expression of activated caspase3. Moreover, we used bioinformatics software and luciferase assay to test whether TNFRSF1A was the target gene of miR-29a. After transfection, qRT-PCR and Western blot was used to detect the expression of TNFRSF1A in AR42J cells after transfection. RESULTS: The expression of miR-29a was much higher in the AEP group compared with the control group as displayed by the miRNA chip assay. After inducing apoptosis of AR42J cells in vitro, the expression of miR-29a was significantly increased by 1.49 ± 0.04 times in comparison with the control group. As revealed by qRT-PCR assay, the expression of miR-29a was 2.68 ± 0.56 times higher in the miR-29a mimic group relative to the control vector group, accompanied with an obviously increased acinar cell apoptosis rate (42.83 ± 1.25 vs 24.97 ± 0.15, P < 0.05). Moreover, the expression of miR-29a in the miRNA AMO group was 0.46 ± 0.05 times lower than the control vector group, and the cell apoptosis rate was much lower accordingly (17.27 ± 1.36 vs 24.97 ± 0.15, P < 0.05). The results of bioinformatics software and luciferase assay showed that TNFRSF1A might be a target gene of miR-29a. TNFRSF1A expression was up-regulated in the miR-29a mimic group, while the miR-29a AMO group showed the reverse trend. CONCLUSION: miR-29a might promote the apoptosis of AR42J cells via up-regulating the expression of its target gene TNFRSF1A.

Functional role of MicroRNA-19b in acinar cell necrosis in acute necrotizing pancreatitis.

The expression of microRNA-19b (miR-19b) in acute necrotizing pancreatitis (ANP) and its functional role in acinar cell necrosis of SD rats were investigated. Twelve SD rats were divided into two groups randomly, including control group and ANP group. The rat ANP models were established by intraperitoneal injection of L-arginine (2400 mg/kg body weight), and equal volume of 0.9% NaCl was injected in the control group. MiRNA chip assay was performed to examine the expression of miRNAs in the pancreas in two different groups. Besides, to further explore the role of miR-19b in ANP in vitro, taurolithocholic acid 3-sulfate disodium salt (TLC-S) (200 µmol/L) was administrated to treat the rat pancreatic acinar cell line, AR42J, for establishing the ANP cells model. The quantitative real-time PCR (qRT-PCR) was adopted to measure the miR-19b expression. Moreover, the mimic miRNA, miRNA antisense oligonucleotide (AMO) and control vector were used to transfect AR42J cells, the expression of miR-19b was confirmed by qRT-PCR and the necrotizing rate of AR42J cells was detected with AO/EB method. The expression of miR-19b was significantly higher in ANP group than in control group as displayed by the miRNA chip assay. Furthermore, after inducing necrosis of AR42J cells in vitro, the expression of miR-19b was significantly increased by 2.51±0.14 times in comparison with the control group. As revealed by qRT-PCR assay, the expression of miR-19b was 5.94±0.95 times higher in the mimic miRNA group than in the control vector group, companied with an obviously increased acinar cell necrotizing rate (50.3%±1.5% vs. 39.6%±2.3%, P<0.05). Moreover, the expression of miR-19b in the miRNA AMO group was 0.38±0.15 times lower than in the control vector group, and the cell necrosis rate was much lower accordingly (23.1%±3.3% vs. 39.6%±2.3%, P<0.05). Besides, there was no significant difference between the control vector cells and the cells without treatment (P>0.05). The expression of miR-19b was significantly induced in ANP. In addition, up-regulation of miR-19b could promote the necrosis of pancreatic acinar cells and miR-19b deficiency could decrease the rate of pancreatic acinar cell necrosis.

Expressions of miR-22 and miR-135a in acute pancreatitis.

This study examined the expressions of miR-22 and miR-135a in rats with acute edematous pancreatitis (AEP) and their target genes in order to shed light on the involvement of miR-22 and miR-135a in the pathogenesis of acute pancreatitis (AP). The in vivo model of AEP was established by introperitoneal injection of L-arginine (150 mg/kg) in rats. The miRNA microarray analysis was used to detect the differential expression of miRNAs in pancreatic tissue in AEP and normal rats. The in vitro AEP model was established by inducing the rat pancreatic acinar cell line (AR42J) with 50 ng/mL recombinant rat TNF-α. Real-time quantitative RT-PCR was employed to detect the expression of miR-22 and miR-135a in AR42J cells. Lentiviruses carrying the miRNA mimic and anti-miRNA oligonucleotide (AMO) of miR-22 and miR-135a were transfected into the AR42J cells. The AR42J cells transfected with vehicle served as control. Western blotting was used to measure the expression of activated caspase3 and flow cytometry analysis to detect the apoptosis of AR42J cells. Targets of miR-22 and miR-135a were predicted by using TargetScan, miRanda, and TarBase. Luciferase reporter assay and quantitative real-time RT-PCR were performed to confirm whether ErbB3 and Ptk2 were the target gene of miR-22 and miR-135a, respectively. The results showed that the expression levels of miR-22 and miR-135a were obviously increased in AEP group compared with the control group in in-vivo and in-vitro models. The expression levels of miR-22 and miR-135a were elevated conspicuously and the expression levels of their target genes were reduced significantly in AR42J cells transfected with lentiviruses carrying the miRNA mimic. The apoptosis rate was much higher in the TNF-α-induced cells than in non-treated cells. The AR42J cells transfected with miRNA AMOs expressed lower level of miR-22 and miR-135a and had lower apoptosis rate, but the expression levels of ErbB3 and Ptk2 were increased obviously. It was concluded that the expression levels of miR-22 and miR-135a were elevated in AEP. Up-regulating the expression of miR-22 and miR-135a may promote the apoptosis of pancreatic acinar cells by repressing ErbB3 and Ptk2 expression in AEP.

[In situ experimental study of phase transition of calcite by Raman spectroscopy at high temperature and high pressure].

The phase transitions of calcite at high temperature and high pressure were investigated by using hydrothermal diamond anvil cell combined with Raman spectroscopy. The result showed that the Raman peak of 155 cm(-1) disappeared, the peak of 1 087 cm(-1) splited into 1083 and 1 090 cm(-1) peaks and the peak of 282 cm(-1) abruptly reduced to 231 cm(-1) at ambient temperature when the system pressure increased to 1 666 and 2 127 MPa respectively, which proved that calcite transformed to calcite-II and calcite-III. In the heating process at the initial pressure of 2 761 MPa and below 171 degrees C, there was no change in Raman characteristic peaks of calcite-III. As the temperature increased to 171 degrees C, the color of calcite crystal became opaque completely and the symmetric stretching vibration peak of 1 087 cm(-1), in-plane bending vibration peak of 713 cm(-1) and lattice vibration peaks of 155 and 282 cm(-1) began to mutate, showing that the calcite-III transformed to a new phase of calcium carbonate at the moment. When the temperature dropped to room temperature, this new phase remained stable all along. It also indicated that the process of phase transformation from calcite to the new phase of calcium carbonate was irreversible. The equation of phase transition between calcite-III and new phase of calcium carbonate can be determined by P(MPa) = 9.09T x (degrees C) +1 880. The slopes of the Raman peak (v1 087) of symmetrical stretching vibration depending on pressure and temperature are dv/dP = 5.1 (cm(-1) x GPa(-1)) and dv/dT = -0.055 3(cm(-1) x degrees C(-1)), respectively.

[Raman spectra study of barite at the pressure of 0-1 GPa and ambient temperature].

The variation characters of Raman spectra of S-O symmetric stretching vibration v987 and symmetric bending vibration v452 and V462 of barite at high pressure were studied using moissanite anvil cell. The experimental results show that barite is stable at the pressure of 0-1 GPa and ambient temperature, and the Raman peak positions of barite shift to higher frequency with increasing pressure. The relations between the Raman shifts and system pressure are given as follows: v987 = 0.004 4p+987.42, v452 = 0.002 3p+452.6, v462 = 0.001 8p+ 462.42, and that stretching vibrations are more affected by pressure than bending vibrations. The intensity of 987 cm(-1) Raman peak of barite is six times greater than that of 464 cm(-1) Raman peak of quartz, so barite can be used as a good pressure gauge. Besides, the relation between the system pressure and Raman shift of 987 cm(-1) peak position of barite is given as follows: p(MPa) = 223.16 X (deltav(p))987 -90.35 (987 cm(-1) < v(p) < 992 cm(-1)). The difference in the measured relative pressure-shift of the Raman line of the symmetric stretching vibration among various sulfate minerals shows the compressibility and strength of the S-O bond in the SO4 group.