Long non-coding RNAs (lncRNAs) are involved in various pathophysiologic processes and human diseases. However, their dynamics and corresponding functions in pulmonary fibrosis remain poorly understood. In this study, portions of lncRNAs adjacent or homologous to protein-coding genes were determined by searching the UCSC genome bioinformatics database. This was found to be potentially useful for exploring lncRNA functions in disease progression. Previous studies showed that competing endogenous RNA (ceRNA) hypothesis is another method to predict lncRNA function. However, little is known about the function of ceRNA in pulmonary fibrosis. In this study, we selected two differentially expressed lncRNAs MRAK088388 and MRAK081523 to explore their regulatory mechanisms. MRAK088388 and MRAK081523 were analysed as long-intergenic non-coding RNAs (lincRNAs), and identified as orthologues of mouse lncRNAs AK088388 and AK081523, respectively. qRT-PCR and in situ hybridization (ISH) showed that they were significantly up-regulated, and located in the cytoplasm of interstitial lung cells. We also showed that MRAK088388 and N4bp2 had the same miRNA response elements (MREs) for miR-200, miR-429, miR-29, and miR-30, whereas MRAK081523 and Plxna4 had the same MREs for miR-218, miR-141, miR-98, and let-7. Moreover, the expression levels of N4bp2 and Plxna4 significantly increased in fibrotic rats, and were highly correlated with those of MRAK088388 and MRAK081523, respectively. Among their shared miRNAs, miR-29b-3p and let-7i-5p decreased in the model group, and were negatively correlated with the expression of MRAK088388 and MRAK081523, respectively. MRAK088388 and MRAK081523 could regulate N4bp2 and Plxna4 expression by sponging miR-29b-3p and let-7i-5p, respectively, and possessed regulatory functions as ceRNAs. Thus, our study may provide insights into the functional interactions of lncRNA, miRNA and mRNA, and lead to new theories for the pathogenesis and treatment of pulmonary fibrosis.

Glucose regulated protein 75 (GRP75) is an important molecular chaperon belonged to the heat shock protein (HSP) family. To evaluate the effect of GRP75 overexpression on PC12 cells under glucose deprivation, cell viability and mitochondrial function of GRP75-overexpressing PC12 cells and the vector transfected control PC12 cells were monitored during glucose deprivation. Upon exposure to glucose deprivation, GRP75-overexpressing PC12 cells exhibited more moderate cell damage than control PC12 cells. Both of the two groups of cells showed a decreased ATP level following an early increase in the condition of glucose deprivation, and the mitochondrial potential were also reduced in the similar manner in the two groups of cells. Control PC12 cells showed an immediate and rapid increase in ROS accumulation after the onset of GD treatment, and this accumulation was slowed and reduced in GRP75-overexpressing PC12 cells. These findings suggested that GRP75 could inhibit the ROS accumulation, and it may be associated with the cytoprotective effect of GRP75 overexpression upon glucose deprivation.

Glucose metabolism plays a pivotal role in many physiological and pathological conditions. To investigate the effect of hypoglycemia (obtained by glucose deprivation) on PC12 cell line, we analyzed the cell viability, mitochondrial function (assessed by MTT reduction, cellular ATP level, mitochondrial transmembrane potential), and the level of reactive oxygen species (ROS) after glucose deprivation (GD). Upon exposure to GD, ROS level increased and MTT reduction decreased immediately, intracellular ATP level increased in the first 3 hours, followed by progressive decrease till the end of GD treatment, and the mitochondrial transmembrane potential (ΔΨm) dropped after 6 hours. Both necrosis and apoptosis occurred apparently after 24 hours which was determined by nuclei staining with propidium iodide(PI) and Hoechst 33342. These data suggested that cytotoxity of GD is mainly due to ROS accumulation and ATP depletion in PC12 cells.

Oxidative stress is an important molecular mechanism underlying lung fibrosis. The mitochondrion is a major organelle for oxidative stress in cells. Therefore, blocking the mitochondrial signalling pathway may be the best therapeutic manoeuver to ameliorate lung fibrosis. Astaxanthin (AST) is an excellent antioxidant, but no study has addressed the pathway of AST against pulmonary oxidative stress and free radicals by the mitochondrion-mediated signalling pathway. In this study, we investigated the antioxidative effects of AST against H2O2- or bleomycin (BLM)-induced mitochondrial dysfunction and reactive oxygen species (ROS) production in alveolar epithelial cells type II (AECs-II) in vivo and in vitro. Our data show that AST blocks H2O2- or BLM-induced ROS generation and dose-dependent apoptosis in AECs-II, as characterized by changes in cell and mitochondria morphology, translocation of apoptotic proteins, inhibition of cytochrome c (Cyt c) release, and the activation of caspase-9, caspase-3, Nrf-2 and other cytoprotective genes. These data suggest that AST inhibits apoptosis in AECs-II cells through the ROS-dependent mitochondrial signalling pathway and may be of potential therapeutic value in lung fibrosis treatment.

Abstract. Recent studies suggest that long non-coding RNAs (lncRNAs) are more involved in human diseases than previously realized. A growing body of evidence links lncRNA mutation and dysregulation to diverse human diseases. However, the association of lncRNAs with the pathogenesis of lung fibrosis remains poorly understood. In this study, we detected changes in hydroxyproline and collagen levels, as well as the ultrastructure of lung tissue to develop a rat model of lung fibrosis. The differentially expressed lncRNAs and mRNA profiles between fibrotic lung and normal lung tissue were analyzed using microarrays. Gene Ontology analysis and pathway analysis were performed for further research. Two differentially expressed lncRNAs, namely, AJ005396 and S69206, were detected by in situ hybridization to validate the microarray data. The results revealed that the number of collagen fibers in the interstitial lung tissue significantly increased in the model group compared with the normal group. In total, 210 and 358 lncRNAs were upregulated and downregulated, respectively, along with 415 upregulated and 530 downregulated mRNAs in the rats with lung fibrosis. AJ005396 and S69206 were upregulated in the fibrotic lung tissue, consistent with the microarray data, and were located in the cytoplasm of the interstitial lung cells. In conclusion, the expression profile of the lncRNAs was significantly altered in the fibrotic lung tissue and these transcripts are potential molecular targets for inhibiting the development of lung fibrosis. IntroductionIdiopathic pulmonary fibrosis (IPF) is a common, chronic, progressive and usually lethal fibrotic lung disease with poor prognosis (1). This disease is characterized by focal areas of alveolar epithelial cell injury and the excessive proliferation of mesenchymal cells in the interstitium, which results in the excessive deposition of extracellular matrix (ECM) and distorted architecture leading to impaired gas exchange (2,3). Although many pathobiological concepts are emerging, including the role of aging and cellular senescence, oxidative stress, endoplasmic reticulum stress, cellular plasticity, microRNA (miRNA) and mechanotransduction, the molecular mechanisms behind IPF are not yet completely understood (4).The Encyclopedia of DNA Elements (ENCODE) project, which aimed to comprehensively characterize the human genome, has shown that >90% of the genome has been transcribed; however, only 1-2% of that is composed of genes (5). The majority of these transcripts are not translated into proteins and are, therefore, termed non-coding RNAs (ncRNAs).Long non-coding RNAs (lncRNAs), a type of ncRNA, vary in size from 200 bp to >100 kb, and are transcribed by RNA polymerase II (6). They play an important role in imprinting (7), enhancing various biological functions (8), X chromosome inactivation (9), chromatin structure (10) and genomic rearrangement during the generation of antibody diversity (11). Thus, lncRNAs are critical for normal development and, in many cases, are deregulated in d...

Noncoding RNAs (ncRNAs), such as microRNA (miRNA), long ncRNA (lncRNA), and circular RNA (circRNA), are regulators of important biological functions. Therefore, understanding their crosstalk and regulatory patterns can provide treatment for diseases. In this study, differentially expressed RNA transcripts were obtained by RNA sequencing in bleomycin-induced pulmonary fibrosis in mice. Four miRNAs, 10 lncRNAs, and two circRNAs were tested to validate the sequencing. There were differentially expressed 585 mRNAs, 236 miRNAs, 272 lncRNAs, and 74 circRNAs in pulmonary fibrosis. Their location on chromosome, length varieties, interaction, and host genes were analyzed. lnc949, circ949, and circ057 were chosen to explore the detailed crosstalk and regulatory pattern, which were measured by using RNA-FISH, dual-luciferase reporter assay, real-time cell analysis and rescue experiment, co-localization analysis, RNA immunoprecipitation, and RNA pull down. The data showed that the three ncRNAs were predominant in the cytoplasm, and their regulatory patterns were focused on post-transcription. The fibrotic function of lnc949 depended on its host gene FKBP5. circ949 and circ057 formed a regulatory network with lnc865 and lnc556 to simultaneously regulate miR-29b-2-5p targeting STAT3 phosphorylation. Collectively, different RNAs can crosstalk with each other to regulate pulmonary fibrosis through different regulatory patterns. We hope these data can provide a full concept of RNA transcripts, leading to a new treatment for pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive type of interstitial pneumonia with unknown causes, poor prognosis and no effective therapy available. Circular RNAs (circRNAs), which serve as potential therapeutic targets and diagnostic biomarkers for certain diseases, represent a recent hotspot in the field of RNA research. In the present study, a total of 67 significantly dysregulated circRNAs were identified in the plasma of IPF patients by using a circRNA microarray. Among these circRNAs, 38 were upregulated, whereas 29 were downregulated. Further validation of the results by polymerase chain reaction analysis indicated that Homo sapiens (hsa)_circRNA_100906, hsa_circRNA_102100 and hsa_circRNA_102348 were significantly upregulated, whereas hsa_circRNA_101225, hsa_circRNA_104780 and hsa_circRNA_101242 were downregulated in plasma samples of IPF patients compared with those in samples from healthy controls. The majority of differentially expressed circRNAs were generated from exonic regions. The host genes of the differentially expressed circRNAs were involved in the regulation of the cell cycle, adherens junctions and RNA transport. The competing endogenous RNA (ceRNA) network of the circRNAs/micro(mi)RNAs/mRNAs indicated that circRNA-protected mRNA participated in transforming growth factor-β1, hypoxia-inducible factor-1, Wnt, Janus kinase, Rho-associated protein kinase, vascular endothelial growth factor, mitogen-activated protein kinase, Hedgehog and nuclear factor κB signalling pathways or functioned as biomarkers for pulmonary fibrosis. Furthermore, luciferase reporter assays confirmed that hsa_circRNA_100906 and hsa_circRNA_102348 directly interact with miR-324-5p and miR-630, respectively, which were downregulated in IPF patients. The present study provided a novel avenue for exploring the underlying molecular mechanisms of IPF disease.

The role of long non-coding RNA (lncRNA) in idiopathic pulmonary fibrosis (IPF) is poorly understood. We found a novel lncRNA-ITPF that was upregulated in IPF. Bioinformatics and in vitro translation verified that lncITPF is an actual lncRNA, and its conservation is in evolution. Northern blot and rapid amplification of complementary DNA ends were used to analyze the full-length sequence of lncITPF. RNA fluorescence in situ hybridization and nucleocytoplasmic separation demonstrated that lncITPF was mainly located in the nucleus. RNA sequencing, chromatin immunoprecipitation (ChIP)-qPCR, CRISPR-Cas9 technology, and promoter activity analysis showed that the fibrotic function of lncITPF depends on its host gene integrin b-like 1 (ITGBL1), but they did not share the same promoter and were not co-transcribed. Luciferase activity, pathway inhibitors, and ChIP-qPCR showed that smad2/3 binds to the lncITPF promoter, and TGF-b1-smad2/3 was the upstream inducer of the fibrotic pathway. Furthermore, RNA-protein pull-down, liquid chromatography-mass spectrometry (LC-MS), and protein-RNA immunoprecipitation showed that lncITPF regulated H3 and H4 histone acetylation in the ITGBL1 promoter by targeting heterogeneous nuclear ribonucleoprotein L. Finally, sh-lncITPF was used to evaluate the therapeutic effect of lncITPF. Clinical analysis showed that lncITPF is associated with the clinicopathological features of IPF patients. Our findings provide a therapeutic target or diagnostic biomarker for IPF.