The long non-coding RNA PFI protects against pulmonary fibrosis by interacting with splicing regulator SRSF1

Patients with hypertrophic scars following severe burn injury express different long noncoding RNAs

OBJECTIVE

Research indicates that long noncoding RNAs (lncRNAs) contribute significantly to fibrotic diseases. Although lncRNAs may play a role in hypertrophic scars after burns, its mechanisms remain poorly understood.

METHODS

Using chip technology, we compared the lncRNA expression profiles of burn patients and healthy controls (HCs). Microarray results were examined by quantitative reverse-transcription polymerase chain reaction (RT-PCR) to verify their reliability. The biological functions of differentially expressed mRNAs and the relationships between genes and signaling pathways were investigated by Gene Ontology (GO) and pathway analyses, respectively.

RESULTS

In contrast with HCs, it was found that 2738 lncRNAs (1628 upregulated) and 2166 mRNAs (1395 upregulated) were differentially expressed in hypertrophic scars after burn. Results from RT-PCR were consistent with those from microarray. GO and pathway analyses revealed that the differentially expressed mRNAs are mainly associated with processes related to cytokine secretion in the immune system, notch signaling, and MAPK signaling.

CONCLUSION

The lncRNA expression profiles of hypertrophic scars after burn changed significantly compared with HCs. It was believed that the transcripts could be used as potential targets for inhibiting abnormal scar formation in burn patients.

LncRNA MIR181A2HG negatively regulates human keratinocytes proliferation by binding SRSF1

Psoriasis is a common chronic inflammatory skin disease. Abnormal proliferation of keratinocytes plays an important role in the pathogenesis of psoriasis. Long non-coding RNAs (lncRNAs) are involved in the regulation of a variety of cell biological processes. The purpose of this study was to investigate the potential role of lncRNA MIR181A2HG in the proliferation of human keratinocytes. qRT-PCR and Western blotting were performed to measure the expression levels of MIR181A2HG, SRSF1, KRT6, and KRT16 in tissue specimens and HaCaT keratinocytes. The effects of MIR181A2HG on HaCaT keratinocytes proliferation were evaluated using Cell Counting Kit-8 (CCK-8) assays, 5-Ethynyl-2'-deoxyuridine (EdU) incorporation, and cell-cycle assays. RNA pulldown-mass spectrometry (MS) was applied to identify the proteins interacting with MIR181A2HG. RNA pull-down-Western blotting and RNA immunoprecipitation coupled with real-time quantitative reverse transcription-PCR (RIP-qRT-PCR) assays were used to determine the interactions between MIR181A2HG and its RNA-binding proteins (RBPs). MIR181A2HG was down-regulated in psoriasis tissues. MIR181A2HG overexpression induced G0/G1 and G2/M phase cell cycle arrest and decreased the protein levels of KRT6, KRT16, Cyclin D1, CDK4, and Cyclin A2 in HaCaT keratinocytes. MIR181A2HG knockdown showed the opposite effect. By using RNA pulldown-MS, 356 proteins were identified to interact with MIR181A2HG potentially. Bioinformatics analysis showed that NOP56 and SRSF1 may be RNA binding proteins (RBPs) that may be interact with MIR181A2HG. Furthermore, by using RNA pull-down-Western blotting and RIP-qRT-PCR, SRSF1 was determined to interact with MIR181A2HG. Moreover, silencing of SRSF1 inhibited keratinocytes proliferation, which could be reversed with the knockdown of MIR181A2HG. Our findings indicated that MIR181A2HG can negatively regulate HaCaT keratinocytes proliferation by binding SRSF1, suggesting that MIR181A2HG and SRSF1 may serve as potential targets for the treatment of psoriasis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00621-6.

High expression of SRSF1 facilitates osteosarcoma progression and unveils its potential mechanisms

BACKGROUND

SRSF1, a member of Serine/Arginine-Rich Splicing Factors (SRSFs), has been observed to significantly influence cancer progression. However, the precise role of SRSF1 in osteosarcoma (OS) remains unclear. This study aims to investigate the functions of SRSF1 and its underlying mechanism in OS.

METHODS

SRSF1 expression level in OS was evaluated on the TCGA dataset, TAGET-OS database. qRT-PCR and Western blotting were employed to assess SRSF1 expression in human OS cell lines as well as the interfered ectopic expression states. The effect of SRSF1 on cell migration, invasion, proliferation, and apoptosis of OS cells were measured by transwell assay and flow cytometry. RNA sequence and bioinformatic analyses were conducted to elucidate the targeted genes, relevant biological pathways, and alternative splicing (AS) events regulated by SRSF1.

RESULTS

SRSF1 expression was consistently upregulated in both OS samples and OS cell lines. Diminishing SRSF1 resulted in reduced proliferation, migration, and invasion and increased apoptosis in OS cells while overexpressing SRSF1 led to enhanced growth, migration, invasion, and decreased apoptosis. Mechanistically, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and Gene Set Enrichment Analysis (GSEA) revealed that the biological functions of SRSF1 were closely associated with the dysregulation of the protein targeting processes, location of the cytosolic ribosome, extracellular matrix (ECM), and proteinaceous extracellular matrix, along with the PI3K-AKT pathway, Wnt pathway, and HIPPO pathway. Transcriptome analysis identified AS events modulated by SRSF1, especially (Skipped Exon) SE events and (Mutually exclusive Exons) MXE events, revealing potential roles of targeted molecules in mRNA surveillance, RNA degradation, and RNA transport during OS development. qRT-PCR confirmed that SRSF1 knockdown resulted in the occurrence of alternative splicing of SRRM2, DMKN, and SCAT1 in OS.

CONCLUSIONS

Our results highlight the oncogenic role of high SRSF1 expression in promoting OS progression, and further explore the potential mechanisms of action. The significant involvement of SRSF1 in OS development suggests its potential utility as a therapeutic target in OS.

Circular RNA Gtdc1 Protects Against Offspring Osteoarthritis Induced by Prenatal Prednisone Exposure by Regulating SRSF1-Fn1 Signaling

Chondrodysplasia is closely associated with low birth weight and increased susceptibility to osteoarthritis in adulthood. Prenatal prednisone exposure (PPE) can cause low birth weight; however, its effect on offspring cartilage development remains unexplored. Herein, rats are administered clinical doses of prednisone intragastrically on gestational days (GDs) 0-20 and underwent long-distance running during postnatal weeks (PWs) 24-28. Knee cartilage is assayed for quality and related index changes on GD20, PW12, and PW28. In vitro experiments are performed to elucidate the mechanism. PPE decreased cartilage proliferation and matrix synthesis, causing offspring chondrodysplasia. Following long-distance running, the PPE group exhibited more typical osteoarthritis-like changes. Molecular analysis revealed that PPE caused cartilage circRNomics imbalance in which circGtdc1 decreased most significantly and persisted postnatally. Mechanistically, prednisolone reduced circGtdc1 expression and binding with Srsf1 to promote degradation of Srsf1 via K48-linked polyubiquitination. This further inhibited the formation of EDA/B+Fn1 and activation of PI3K/AKT and TGFβ pathways, reducing chondrocyte proliferation and matrix synthesis. Finally, intra-articular injection of offspring with AAV-circGtdc1 ameliorated PPE-induced chondrodysplasia, but this effect is reversed by Srsf1 knockout. Altogether, this study confirms that PPE causes chondrodysplasia and susceptibility to osteoarthritis by altering the circGtdc1-Srsf1-Fn1 axis; in vivo, overexpression of circGtdc1 can represent an effective intervention target for ameliorating PPE-induced chondrodysplasia.

Identification of non-coding RNA signatures in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a deadly, chronic, progressive, irreversible interstitial lung disease characterized by the formation of scar tissue resulting in permanent lung damage. The average survival time following diagnosis is only 3-5 years, with a 5-year survival rate shorter than that of many cancers. Alveolar epithelial cell injury followed by irregular repair is the primary pathological process observed in patients with IPF. An evident characteristic of IPF is the development of fibroblastic foci representing active fibrotic areas. Most of the cells within these foci are believed to be myofibroblasts, which are thought to be the primary source of abnormal extracellular matrix production in IPF. The lung phenotype in IPF is characterized by significantly different processes from healthy lungs, including irregular apoptosis, oxidative stress, and epithelial-mesenchymal transition (EMT) pathways.

AIMS

The exact cause of IPF is not fully understood and remains mysterious. It is not suppressing that non-coding RNAs are involved in the development and progression of IPF. Accordingly, here we aimed to identify non-coding RNA molecules during TGFβ-induced myofibroblast activation.

METHODS

Differential expression and functional enrichment analysis were employed to reveal the impact of non-coding RNAs during TGFβ-associated lung fibrosis.

RESULTS

Remarkably, LOC101448202, CZ1P-ASNS, LINC01503, IER3-AS1, MIR503HG, CLMAT3, LINC02593, ACTA2-AS1, LOC102723692, LOC107985728, and LOC105371064 were identified to be differentially altered during TGFβ-stimulated myofibroblast activation.

CONCLUSIONS

These findings strongly suggest that the mechanism of lung fibrosis is heavily under control of non-coding RNAs, and RNA-based therapies could be a promising approach for future therapeutic interventions to lung fibrosis.

HSFAS mediates fibroblast proliferation, migration, trans-differentiation and apoptosis in hypertrophic scars via interacting with ADAMTS8

Hypertrophic scar (HS) is one of the most common sequelae of patients, especially after burns and trauma. The roles of regulatory long noncoding RNAs (lncRNAs) in mediating HS remain underexplored. Human hypertrophic scar-derived fibroblasts (HSFBs) have been shown to exert more potent promoting effects on extracellular matrix (ECM) accumulation than normal skin-derived fibroblasts (NSFBs) and are associated with enhanced HS formation. The purpose of this study is to search for lncRNAs enriched in HSFBs and investigate their roles and mechanisms. LncRNA MSTRG.59347.16 is one of the most highly expressed lncRNAs in HS detected by lncRNA-seq and qRT-PCR and named as hypertrophic scar fibroblast-associated lncRNA (HSFAS). HSFAS overexpression significantly induces fibroblast proliferation, migration, and myofibroblast trans-differentiation and inhibits apoptosis in HSFBs, while knockdown of HSFAS results in augmented apoptosis and attenuated proliferation, migration, and myofibroblast trans-differentiation of HSFBs. Mechanistically, HSFAS suppresses the expression of A disintegrin and metalloproteinase with thrombospondin motifs 8 (ADAMTS8). ADAMTS8 knockdown rescues downregulated HSFAS-mediated fibroblast proliferation, migration, myofibroblast trans-differentiation and apoptosis. Thus, our findings uncover a previously unknown lncRNA-dependent regulatory pathway for fibroblast function. Targeted intervention in the HSFAS-ADAMTS8 pathway is a potential therapy for HS.

Proteomics and phosphoproteomics to study Tuina reverses capsule fibrosis in frozen shoulder: a research report based on rats

Frozen shoulder (FS) is a common disorder often treated with Tuina, but the mechanisms involved remain unclear. We employed proteomics and phosphoproteomics to investigate the mechanisms associated with the treatment of capsule fibrosis in FS rats. We used a method composed of three weeks of cast immobilization to establish a model of FS. We then administered Tuina once daily for 14 days, evaluated glenohumeral range of motion (ROM), assessed histological changes, and identified differentially expressed proteins (DEPs) using proteomics and phosphoproteomics. This study demonstrated that Tuina could improve glenohumeral ROM and reserve capsule fibrosis in FS rats. Proteomics revealed proteins regulated by Tuina belonging to the PI3K-AKT and ECM receptor interaction signaling pathways. Phosphoproteomics detected differentially phosphorylated proteins regulated by Tuina to be enriched in the MAPK signaling pathway. The combination of proteomics and phosphoproteomics for Protein-Protein Interaction (PPI) network analysis revealed that the phosphorylation of Myh3 and Srsf1 with a node degree larger than the average degree were considered the central regulatory protein modulated by Tuina to reverse capsule fibrosis. Thbs1, Vtn, and Tenascin-W were significantly enriched in PI3K-AKT and ECM receptor interaction signaling pathways and highly expressed in model rats. Tuina resulted in reduced expression of these proteins. Our findings demonstrated some of mechanisms behind the reversal of FS capsule fibrosis following Tuina, a scientific medical therapy for FS patients.

Inhibition of ferroptosis by POLE2 in gastric cancer cells involves the activation of NRF2/GPX4 pathway

Gastric cancer results in great cancer mortality worldwide, and inducing ferroptosis dramatically improves the malignant phenotypes of gastric cancer. DNA polymerase epsilon subunit 2 (POLE2) plays indispensable roles in tumorigenesis; however, its involvement and molecular basis in ferroptosis and gastric cancer are not clear. Human gastric cancer cells were infected with lentiviral vectors to knock down or overexpress POLE2, and cell ferroptosis was detected. To further validate the involvement of nuclear factor erythroid 2-related factor 2 (NRF2) and glutathione peroxidase 4 (GPX4), lentiviral vectors were used. POLE2 expression was elevated in human gastric cancer cells and tissues and closely correlated with clinicopathological features in gastric cancer patients. POLE2 knockdown was induced, while POLE2 overexpression inhibited ferroptosis of human gastric cancer cells, thereby modulating the malignant phenotypes of gastric cancer. Mechanistic studies revealed that POLE2 overexpression elevated NRF2 expression and activity and subsequently activated GPX4, which then prevented lipid peroxidation and ferroptosis in human gastric cancer cells. In contrast, either NRF2 or GPX4 silence significantly prevented POLE2 overexpression-mediated inductions of cell proliferation, migration, invasion and inhibition of ferroptosis. POLE2 overexpression inhibits ferroptosis in human gastric cancer cells through activating NRF2/GPX4 pathway, and inhibiting POLE2 may be a crucial strategy to treat gastric cancer.

LncRNA AP000487.1 regulates PRKCB DNA methylation-mediated TLR4/MyD88/NF-κB pathway in Nano NiO-induced collagen formation in BEAS-2B cells

Nickel oxide nanoparticles (Nano NiO) have been shown to cause pulmonary fibrosis; But, the underlying epigenetic mechanisms remain poorly understood. In this study, we aimed to investigate the role of lncRNA AP000487.1 in regulating PRKCB DNA methylation and the Toll-like receptor 4 (TLR4)/ Myeloid differentiation primary response 88 (MyD88)/ Nuclear factor kappa-B (NF-κB) pathway in Nano NiO-induced collagen formation. We found that lncRNA AP000487.1 was able to bind to the promoter region of the PRKCB gene by Chromosomal RNA pull-down experiments (Ch-RNA pull-down). Moreover, Nano NiO exposure led to down-regulation of lncRNA AP000487.1 expression and PRKCB DNA methylation, resulting in up-regulation of PRKCB expression, activation of the TLR4/MyD88/NF-κB pathway, and increased collagen formation in BEAS-2B cells. Conversely, overexpression of lncRNA AP000487.1 restored PRKCB expression, reduced its hypomethylation and attenuated TLR4/MyD88/NF-κB pathway activation and collagen formation. Furthermore, treatment with the DNA methylation inhibitor, decitabine, alleviated Nano NiO-induced PRKCB2 expression, TLR4/MyD88/NF-κB pathway activation, and collagen formation. Additionally, using PRKCB2 overexpression plasmid, PRKCB2 siRNA, and PRKCB2 protein inhibitor LY317615 influenced NF-κB pathway activity and collagen formation. Finally, TLR4 inhibitor (TAK-242) restrained Nano NiO-induced MyD88/NF-κB pathway activation and excessive collagen formation. In summary, we demonstrated that the down-regulated lncRNA AP000487.1 could cause PRKCB hypomethylation and increased expression, resulting in NF-κB pathway activation and collagen formation in Nano NiO-induced BEAS-2B cells. This is the first study to reveal the role of lncRNA AP000487.1 in regulating collagen formation in Nano NiO-exposed BEAS-2B cells. Our study identified that lncRNA AP000487.1/PRKCB hypomethylation/NF-κB pathway was a regulatory axis of BEAS-2B cells collagen excessive formation. Our findings indicate that lncRNA AP000487.1 and PRKCB DNA methylation may function as biomarkers or potential targets in response to Nano NiO exposure.

Circ_0001666 upregulation promotes intestinal epithelial cell fibrosis in pediatric Crohn's disease via the SRSF1/BMP7 axis

The epithelial-mesenchymal transition (EMT) is closely associated with Crohn's disease (CD) related intestinal fibrosis, a condition whose prevalence is increasing annually among children. Recently, the CD marker gene microarray screening revealed an upregulation of circ_0001666 in the colon tissues of CD patients, but its underlying mechanisms remain unclear. In this study, we explored the molecular mechanism of circ_0001666 in regulating EMT-mediated fibrosis in CD in vitro. The levels of circ_0001666 and EMT-associated proteins were assessed in CD clinical samples, and a CD cell model was established using TGF-β1 to induce human intestinal epithelial cells (HIECs). Additionally, the expression levels of genes and proteins related to EMT and fibrosis were analyzed by quantitative real-time PCR and western blot, cell migration, and invasion were assessed via wound healing assay and transwell, respectively, and RNA pull-down and RNA immunoprecipitation assays were performed to verify the relationship between SRSF1 and BMP7 or circ_0001666. Circ_0001666 was overexpressed in the intestinal mucosal tissues of CD patients and was positively correlated with EMT. Silencing circ_0001666 inhibited the migration, invasion, EMT, and fibrosis of HIECs induced by TGF-β1. Mechanistically, circ_0001666 regulated BMP7 expression by interacting with SRSF1. Furthermore, the effects of inhibiting circ_0001666 on HIECs could be partially reversed by overexpressing SRSF1 or silencing BMP7. Collectively, circ_0001666 regulates TGF-β1-induced HIEC migration, invasion, EMT, and fibrosis. Circ_0001666 also promoted EMT-mediated fibrosis by interacting with SRSF1 to accelerate BMP7 mRNA decay. These findings provide new insights into the pathogenesis of CD and suggest that circ_0001666 might be a potential therapeutic target for CD.

Fibroblast Upregulation of Vitamin D Receptor Represents a Self-Protective Response to Limit Fibroblast Proliferation and Activation during Pulmonary Fibrosis

Dysregulation of vitamin D receptor (VDR) is implicated in chronic obstructive pulmonary disease. However, whether VDR dysregulation contributes to the development of pulmonary fibrosis remains largely unknown. Analysis of bulk and single-cell RNA profiling datasets revealed VDR upregulation in lung fibroblasts from patients with pulmonary fibrosis or fibrotic mice, which was validated in lung fibroblasts from bleomycin-exposed mice and bleomycin-treated fibroblasts. Stable VDR knockdown promoted, whereas the VDR agonist paricalcitol suppressed lung fibroblast proliferation and activation. Gene set enrichment analysis (GSEA) showed that the JAK/STAT pathway and unfolded protein response (UPR), a process related to endoplasmic reticulum (ER) stress, were enriched in lung fibroblasts of fibrotic lungs. Stable VDR knockdown stimulated, but paricalcitol suppressed ER stress and JAK1/STAT3 activation in lung fibroblasts. The STAT3 inhibitor blocked bleomycin- or stable VDR knockdown-induced ER stress. Paricalcitol inhibited the bleomycin-induced enrichment of STAT3 to the ATF6 promoter, thereby suppressing ATF6 expression in fibroblasts. Paricalcitol or intrapulmonary VDR overexpression inactivated JAK1/STAT3 and suppressed ER stress in bleomycin-treated mice, thus resulting in the inhibition of fibroblast proliferation and activation. Collectively, this study suggests that fibroblast VDR upregulation may be a self-protective response to limit fibroblast proliferation and activation during pulmonary fibrosis by suppressing the JAK1/STAT3/ER stress pathway.

The Role of miR-1183: A Potential Suppressor in Hepatocellular Carcinoma via Regulating Splicing Factor SRSF1

Purpose

Hepatocellular carcinoma (HCC) is a severe global health problem, causing many deaths of patients all over the world. Serine and arginine-rich splicing factor 1 (SRSF1) functions as an important oncogenic role in tumorigenesis and progression in HCC. Therefore, therapies targeting SRSF1 may provide promising therapeutic approaches. MiRNAs are virtually involved at the post-transcriptional level and bind to 3' untranslated region (3'-UTR) of their target messenger RNA (mRNA) to suppress expression.

Methods

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the expression of SRSF1 and miR-1183 in HCC cell lines. CCK8 assay, colony formation assay and wound healing assay were used to detect the function of miR-1183 in HCC cell lines in vitro. Luciferase reporter assay and Western blot were applied to detect the regulation of particular molecules. Xenograft tumor assay was used to detect the function of miR-1183 in HCC cell lines in vivo. Immunohistochemistry (IHC) was used to detect the expression of SRSF1 in HCC tissues and Xenograft tumors.

Results

In this study, we identified that miR-1183 was downregulated in HCC cell lines. Functional assays indicated that miR-1183-upregulation cells show weakened proliferation ability and migration ability in vitro and inhibit subcutaneous tumor formation in vivo. With respect to the underlying mechanism, we found that miR-1183 function as a tumor suppressor by specifically binding to SRSF1.

Conclusion

This study is the first to demonstrate that miR-1183 function as an important tumor-suppressing role by binding to the 3'-UTR of SRSF1 mRNA and suppressing its protein level in HCC cells in vitro and in vivo. Further, miR-1183 may be a potential target in the prognosis and treatment of HCC.

Pachymic acid protects hepatic cells against oxygen-glucose deprivation/reperfusion injury by activating sirtuin 1 to inhibit HMGB1 acetylation and inflammatory signaling

Ischemia-reperfusion injury is an important cause of liver injury occurring during liver transplantation. It is usually caused by inflammatory response and oxidative stress-induced oxidative damage. Pachymic acid (PA) has various biological activities such as anti-inflammatory, antioxidant and anti-cancer. However, the action mechanism of PA in hepatic ischemia-reperfusion injury is currently unknown. In this study, liver cells were subjected to oxygen-glucose deprivation/reperfusion (OGD/R) to simulate a hepatic ischemia-reperfusion injury model. The binding relationship between PA and sirtuin 1 (SIRT1) was analyzed by molecular docking. Cell viability was detected by Cell Counting Kit-8. Expression levels of SIRT1 and high mobility group box 1 (HMGB1) were detected by western blot. Subsequent levels of inflammatory factors were detected by related kits and western blot. Meanwhile, related kits were used to examine levels of oxidative stress markers including reactive oxygen species, malondialdehyde, superoxide dismutase and cytotoxicity-associated lactate dehydrogenase. Finally, cell apoptosis was detected by flow cytometry and western blot. The results showed that PA significantly ameliorated OGD/R-induced decrease in SIRT1 expression, increase in HMGB1 acetylation and HMGB1 translocation. Moreover, the elevated levels of inflammatory factors, oxidative stress indexes and cell apoptosis upon exposure to OGD/R were reversed by PA treatment. Moreover, the addition of SIRT1 agonist and inhibitor further demonstrated that PA exerted the aforementioned effects in OGD/R-exposed cells by targeting SIRT1. Thus, the present study revealed the mechanism by which PA ameliorated OGD/R-induced hepatic injury via SIRT1. These results might provide a clearer theoretical basis for the targeted treatment of OGD/R-induced hepatic injury with PA.

Serine and arginine rich splicing factor 1: a potential target for neuroprotection and other diseases

Alternative splicing is the process of producing variably spliced mRNAs by choosing distinct combinations of splice sites within a messenger RNA precursor. This splicing enables mRNA from a single gene to synthesize different proteins, which have different cellular properties and functions and yet arise from the same single gene. A family of splicing factors, Serine-arginine rich proteins, are needed to initiate the assembly and activation of the spliceosome. Serine and arginine rich splicing factor 1, part of the arginine/serine-rich splicing factor protein family, can either activate or inhibit the splicing of mRNAs, depending on the phosphorylation status of the protein and its interaction partners. Considering that serine and arginine rich splicing factor 1 is either an activator or an inhibitor, this protein has been studied widely to identify its various roles in different diseases. Research has found that serine and arginine rich splicing factor 1 is a key target for neuroprotection, showing its promising potential use in therapeutics for neurodegenerative disorders. Furthermore, serine and arginine rich splicing factor 1 might be used to regulate cancer development and autoimmune diseases. In this review, we highlight how serine and arginine rich splicing factor 1 has been studied concerning neuroprotection. In addition, we draw attention to how serine and arginine rich splicing factor 1 is being studied in cancer and immunological disorders, as well as how serine and arginine rich splicing factor 1 acts outside the central or peripheral nervous system.

Long non-coding RNA PFI inhibits apoptosis of alveolar epithelial cells to alleviate lung injury via miR-328-3p/Creb1 axis

Acute lung injury (ALI), a common clinical type of critical illness, is an acute hypoxic respiratory insufficiency caused by the damage of alveolar epithelial cells and capillary endothelial cells. In a previous study, we reported a novel lncRNA, lncRNA PFI, which could protect against pulmonary fibrosis in pulmonary fibroblasts. The present study demonstrated that lncRNA PFI was downregulated in alveolar epithelial cell of mice injury lung tissues, and further investigated the role of lncRNA PFI in regulating inflammation-induced alveolar epithelial cell apoptosis. Overexpression of lncRNA PFI could partially abrogated bleomycin induced type II AECs injured. Subsequently, bioinformatic prediction revealed that lncRNA PFI might directly bind to miR-328-3p, and further AGO-2 RNA binding protein immunoprecipitation (RIP) assay confirmed their binding relationship. Furthermore, miR-328-3p promoted apoptosis in MLE-12 cells by limiting the activation of the Creb1, a protein correlated with cell apoptosis, whereas AMO-328-3p ablated the pro-apoptosis effect of silencing lncRNA PFI in MLE-12 cells. While miR-328-3p could also ablate the function of lncRNA PFI in bleomycin treated human lung epithelial cells. Enhanced expression of lncRNA PFI reversed the LPS-induced lung injury in mice. Overall, these data reveal that lncRNA PFI mitigated acute lung injury through miR-328-3p/Creb1 pathway in alveolar epithelial cells.

LncRNA AC006064.4-201 serves as a novel molecular marker in alleviating cartilage senescence and protecting against osteoarthritis by destabilizing CDKN1B mRNA via interacting with PTBP1

BACKGROUND

Osteoarthritis (OA) is the most prevalent age-related disease in the world. Chondrocytes undergo an age-dependent decline in their proliferation and synthetic capacity, which is the main cause of OA development. However, the intrinsic mechanism of chondrocyte senescence is still unclear. This study aimed to investigate the role of a novel long non-coding RNA (lncRNA), AC006064.4-201 in the regulation of chondrocyte senescence and OA progression and to elucidate the underlying molecular mechanisms.

METHODS

The function of AC006064.4-201 in chondrocytes was assessed using western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) and β-galactosidase staining. The interaction between AC006064.4-201 and polypyrimidine tract-binding protein 1 (PTBP1), as well as cyclin-dependent kinase inhibitor 1B (CDKN1B), was evaluated using RPD-MS, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP) and RNA pull-down assays. Mice models were used to investigate the role of AC006064.4-201 in post-traumatic and age-related OA in vivo.

RESULTS

Our research revealed that AC006064.4-201 was downregulated in senescent and degenerated human cartilage, which could alleviate senescence and regulate metabolism in chondrocytes. Mechanically, AC006064.4-201 directly interacts with PTBP1 and blocks the binding between PTBP1 and CDKN1B mRNA, thereby destabilizing CDKN1B mRNA and decreasing the translation of CDKN1B. The in vivo experiments were consistent with the results of the in vitro experiments.

CONCLUSIONS

The AC006064.4-201/PTBP1/CDKN1B axis plays an important role in OA development and provides new molecular markers for the early diagnosis and treatment of OA in the future. Schematic diagram of AC006064.4-201 mechanism. A schematic diagram of the mechanism underlying the effect of AC006064.4-201.

Inhibition of ANGPT2 activates autophagy during hypertrophic scar formation via PI3K/AKT/mTOR pathway

BACKGROUND

Hypertrophic scar (HS), a fibroproliferative disorder caused by aberrant wound healing following skin injuries such as burns, lacerations and surgery, is characterized by invasive proliferation of fibroblasts and excessive extracellular matrix (ECM) accumulation. The dysregulation of autophagy is the pathological basis of HS formation. Previously, angiopoietin-2 (ANGPT2) was found to be overexpressed in HS fibroblasts (HSFs) compared with normal skin fibroblasts. However, whether ANGPT2 participates in the process of HS formation and the potential molecular mechanisms are not clear.

OBJECTIVE

This study is intended to figure out the role of ANGPT2 and ANGPT2-mediated autophagy during the development of HS.

METHODS

RT-qPCR was used to detect ANGPT2 expression in HS tissues and HSFs. HSFs were transfected with sh-ANGPT2 to knock down ANGPT2 expression and then treated with MHT1485, the mTOR agonist. The effects of sh-ANGPT2 or MHT1485 on the proliferation, migration, autophagy and ECM accumulation of HSFs were evaluated by CCK-8 assay, Transwell assay and western blotting. The expression of PI3K/Akt/mTOR pathway-related molecules (p-PI3K, p-Akt and p-mTOR) was assessed by western blotting.

RESULTS

ANGPT2 expression was markedly upregulated in HS tissues and HSFs. ANGPT2 knockdown decreased the expression of p-PI3K, p-Akt and p-mTOR. ANGPT2 knockdown activated autophagy and inhibited the proliferation, migration, and ECM accumulation of HSFs. Additionally, the treatment of MHT1485, the mTOR agonist, on ANGPT2-downregulated HSFs, partially reversed the influence of ANGPT2 knockdown on HSFs.

STUDY LIMITATIONS

The study lacks the establishment of more stable in vivo animal models of HS for investigating the effects of ANGPT2 on HS formation in experimental animals.

CONCLUSIONS

ANGPT2 downregulation represses growth, migration, and ECM accumulation of HSFs via autophagy activation by suppressing the PI3K/Akt/mTOR pathway. Our study provides a novel potential therapeutic target for HS.

Macrophage Sprouty4 deficiency diminishes sepsis-induced acute lung injury in mice

OBJECTIVE

Inflammation and oxidative stress play critical roles in sepsis-induced acute lung injury (ALI). Sprout4 (Spry4) is involved in regulating inflammation and tissue injury; however, its role and mechanism in sepsis-induced ALI remain elusive.

METHODS

Macrophage-specific Spry4 knockout (Spry4^MKO), transgenic (Spry4^MTG) mice and matched control littermates were generated and exposed to cecum ligation and puncture (CLP) surgery to establish bacterial sepsis-induced ALI. Bone marrow-derived macrophages (BMDMs) from Spry4^MKO or Spry4^MTG mice were isolated and subjected to lipopolysaccharide (LPS) stimulation to further validate the role of Spry4 in vitro. To verify the necessity of AMP-activated protein kinase (AMPK), Spry4 and AMPK double knockout mice and compound C were used in vivo and in vitro. BMDMs were treated with STO-609 to inhibit calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2).

RESULTS

We found that macrophage Spry4 was increased in CLP mice and positively correlated with sepsis-induced ALI. Macrophage Spry4 deficiency prevented, while macrophage Spry4 overexpression exacerbated sepsis-induced inflammation, oxidative stress and ALI in mice and BMDMs. Mechanistic studies revealed that macrophage Spry4 deficiency alleviated sepsis-induced ALI through activating CaMKK2/AMPK pathway.

CONCLUSION

Our study identify macrophage Spry4 as a promising predictive and therapeutic target of sepsis-induced ALI.

The silencing of lnc-NONHSAT071210 suppresses the proliferation, fibrosis, migration, and invasion of TGFβ1-treated lung epithelial cells

Background

Pulmonary fibrosis, which is a frequent manifestation of connective tissue disease (CTD), is a leading cause of morbidity and mortality. However, the role of long non-coding ribonucleic acids (lncRNAs) in CTD-associated pulmonary fibrosis requires clarification. This study sought to examine the effects of lnc-NONHSAT071210 on the phenotypes of transforming growth factor β1 (TGFβ1)-treated lung epithelial cells.

Methods

The GeneChip was used to identify differentially expressed lncRNAs in CTD-associated pulmonary fibrosis patients. After lnc-NONHSAT071210 was knocked down in the TGFβ1-challenged lung epithelial cells, cell viability, cell cycle, migration, and invasion were estimated by Cell Counting Kit-8 assays, a flow cytometry analysis, wound-healing assays, and transwell assays, respectively. The expression and levels of the fibrosis-associated factors were examined by enzyme-linked immunosorbent assays, RT-qPCR, and western blots.

Results

The expression of the top 7 most significantly upregulated lncRNAs in the CTD-associated pulmonary fibrosis patients was depicted in a heat map and examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results showed that the expression of lnc-NONHSAT071210 was significantly increased in the tissues of the CTD-associated pulmonary fibrosis patients (P<0.001). The silencing of Lnc-NONHSAT071210 suppressed proliferation, migration, and invasion in the TGFβ1-exposed alveolar epithelial cells (P<0.001).

Conclusions

Thus, lnc-NONHSAT071210 expression was increased in the tissues of the CTD-associated pulmonary fibrosis patients and TGFβ1-treated lung epithelial cells, and TGFβ1-induced lung epithelial cell injury was alleviated by impeding the expression of lnc-NONHSAT071210.

Long Non-Coding RNAs in Cardiac and Pulmonary Fibroblasts and Fibrosis

The cardiopulmonary system delivers oxygen throughout the body via blood circulation. It is an essential part of the body to sustain the lives of organisms. The integral parts of the cardiopulmonary system—the heart and lungs—are constantly exposed to damaging agents (e.g., dust, viruses), and can be greatly affected by injuries caused by dysfunction in tissues (e.g., myocardial infarction). When damaged, mesenchymal cells, such as fibroblasts, are activated to become myofibroblasts to initiate fibrosis as part of a regenerative mechanism. In diseased states, the excess accumulation of extracellular matrices secreted by myofibroblasts results in further dysfunction in the damaged organs. These fibrotic tissues cannot easily be removed. Thus, there is a growing interest in understanding the fibrotic process, as well as finding biomolecules that can be targets for slowing down or potentially stopping fibrosis. Among these biomolecules, the interest in studying long non-coding RNAs (lncRNAs; any non-protein-coding RNAs longer than 200 nucleotides) has intensified in recent years. In this commentary, we summarize the current status of lncRNA research in the cardiopulmonary system by focusing on cardiac and pulmonary fibrosis.

Systematic analyses identify the anti-fibrotic role of lncRNA TP53TG1 in IPF

Long non-coding RNA (lncRNA) was reported to be a critical regulator of cellular homeostasis, but poorly understood in idiopathic pulmonary fibrosis (IPF). Here, we systematically identified a crucial lncRNA, p53-induced long non-coding RNA TP53 target 1 (TP53TG1), which was the dysregulated hub gene in IPF regulatory network and one of the top degree genes and down-regulated in IPF-drived fibroblasts. Functional experiments revealed that overexpression of TP53TG1 attenuated the increased expression of fibronectin 1 (Fn1), Collagen 1α1, Collagen 3α1, ACTA2 mRNA, Fn1, and Collagen I protein level, excessive fibroblasts proliferation, migration and differentiation induced by TGF-β1 in MRC-5 as well as PMLFs. In vivo assays identified that forced expression of TP53TG1 by adeno-associated virus 5 (AAV5) not only prevented BLM-induced experimental fibrosis but also reversed established lung fibrosis in the murine model. Mechanistically, TP53TG1 was found to bind to amount of tight junction proteins. Importantly, we found that TP53TG1 binds to the Myosin Heavy Chain 9 (MYH9) to inhibit its protein expression and thus the MYH9-mediated activation of fibroblasts. Collectively, we identified the TP53TG1 as a master suppressor of fibroblast activation and IPF, which could be a potential hub for targeting treatment of the disease.

LDLR dysfunction induces LDL accumulation and promotes pulmonary fibrosis

Treatments for pulmonary fibrosis (PF) are ineffective because its molecular pathogenesis and therapeutic targets are unclear. Here, we show that the expression of low-density lipoprotein receptor (LDLR) was significantly decreased in alveolar type II (ATII) and fibroblast cells, whereas it was increased in endothelial cells from systemic sclerosis-related PF (SSc-PF) patients and idiopathic PF (IPF) patients compared with healthy controls. However, the plasma levels of low-density lipoprotein (LDL) increased in SSc-PF and IPF patients. The disrupted LDL-LDLR metabolism was also observed in four mouse PF models. Upon bleomycin (BLM) treatment, Ldlr-deficient (Ldlr-/-) mice exhibited remarkably higher LDL levels, abundant apoptosis, increased fibroblast-like endothelial and ATII cells and significantly earlier and more severe fibrotic response compared to wild-type mice. In vitro experiments revealed that apoptosis and TGF-β1 production were induced by LDL, while fibroblast-like cell accumulation and ET-1 expression were induced by LDLR knockdown. Treatment of fibroblasts with LDL or culture medium derived from LDL-pretreated endothelial or epithelial cells led to obvious fibrotic responses in vitro. Similar results were observed after LDLR knockdown operation. These results suggest that disturbed LDL-LDLR metabolism contributes in various ways to the malfunction of endothelial and epithelial cells, and fibroblasts during pulmonary fibrogenesis. In addition, pharmacological restoration of LDLR levels by using a combination of atorvastatin and alirocumab inhibited BLM-induced LDL elevation, apoptosis, fibroblast-like cell accumulation and mitigated PF in mice. Therefore, LDL-LDLR may serve as an important mediator in PF, and LDLR enhancing strategies may have beneficial effects on PF.