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

Abstract

AIMTo 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.METHODSOne 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.RESULTSAfter 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.CONCLUSIONGR transcriptionally represses the expression of miR-22, which further promotes the apoptosis of pancreatic acinar cells by downregulating the downstream signaling pathway.

Circulating extracellular vesicle‑encapsulated microRNA as screening biomarkers for intraductal papillary mucinous neoplasm

“…While we cannot find any relevant data regarding miR-6132 and tumors, the expression of miR-22 and miR-4539 in cancer tissue has been studied in gastric cancer, rhabdomyosarcoma, breast cancer, prostate cancer, osteosarcoma and papillary thyroid cancer (21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Most studies have reported that, in contrast to their expression levels in the blood, the expression levels of these miRNAs are decreased in cancer tissue.…”

Role of microRNAs and long non‑coding RNAs in glucocorticoid signaling (Review)

“…This is the case for miR-124-3p, where differential splicing produces the GRb isoform, no longer harboring its binding site, which in turn acts as a negative inhibitor of GRα (90,162). Tying this to recent studies, demonstrating that the GR can itself influence miRNA expression profiles (125)(126)(127), the intricacies of miRNA-GR regulation and response to GCs are becoming exponentially complex.…”

“…In an in vitro study, miR-22 expression was shown to be elevated in AR42J cells following the induction of apoptosis. A GR binding site was identified in the promoter region of miR-22, while GR was shown to be able to repress miR-22 expression (125). In addition, a recent profiling study in triple-negative breast cancer suggested the ability of GR to influence multiple miRNA expression profiles (126), while in the study by Tejos-Bravo et al (127), neuron-specific GR knockout mice exhibited altered miRNA expression profiles in a sex-dependent manner.…”

Mode of Action of Shan‐Zhu‐Yu (Cornus officinalis Sieb. et Zucc.) in the Treatment of Depression Based on Network Pharmacology

“…Genes involved in the neuroactive ligand-receptor interaction signaling pathway and apoptosis signaling pathway are likely related to the pathological mechanism of depression; therefore, genes in these pathways are key targets for the treatment of depression. Additionally, the connection between these pathways in depression may be a focus in the study of depression [ 22 ].…”

“…Furthermore, NR3C1 , which encodes GR, is related to affective disorders , and any abnormalities in NR3C1 affect the function and activity of GR, thereby leading to disorders of the neuroendocrine system [ 27 ]. Moreover, NR3C1 downregulation promotes the expression of micro-RNA-22, which results in the increased expression of downstream genes, namely, Bcl-2-associated agonist of cell death, Bax , and caspase-3 , and decreased expression of Bcl-2 and Bcl-xL , thereby promoting cell apoptosis [ 22 ].…”