LncRNA GAS5 suppresses inflammatory responses and apoptosis of alveolar epithelial cells by targeting miR-429/DUSP1
Introduction
Acute lung injury (ALI), along with its severe form acute respiratory distress syndrome (ARDS), is a life-threatening syndrome with high rates of morbidity and mortality (Butt et al., 2016). ALI is characterized by increased alveolar-capillary membrane permeability, diffuse alveolar damage, edema, excessive pulmonary inflammation and apoptosis of alveolar epithelial cells (Butt et al., 2016; Favarin et al., 2013). Lipopolysaccharide (LPS), a major constituent of the outer membrane of Gram-negative bacteria, is one of the primary causative factors of ALI caused by bacterial infections (Yan et al., 2019). Therefore, LPS administration has been widely used as a common model of ALI, which was characterized by enhanced alveolar epithelial cell inflammation and apoptosis (Jiang et al., 2018; Ju et al., 2018; Lei et al., 2018a; Li et al., 2018e).
Long non-coding RNAs (lncRNAs) are a class of non-protein coding transcripts with the length longer than 200 nucleotides. LncRNAs are implicated in various biological functions and play an important role in the pathogenesis of many inflammatory diseases including ALI. For example, knockdown of lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcription 1) led to inhibition of inflammatory responses in LPS-induced ALI rat model (Dai et al., 2018). Growth arrest-specific 5 (GAS5) is a lncRNA that generally plays a tumor suppressor role and acts as a putative therapeutic target in human malignancies (Ghaforui-Fard and Taheri, 2019). Sun et al. (2016) screened the differentially expressed lncRNAs in the lung tissues from paraquat-induced ALI mice, and found that GAS5 (ENSMUST00000065709) was significantly down-regulated in lung tissues of ALI mice, suggesting that GAS5 may play a protective role in ALI. However, the exact role and mechanisms of GAS5 in ALI remain unclear.
Recently, lncRNAs have been well known to exert roles by functioning as a competitive endogenous RNA (ceRNA) to segregate microRNAs (miRNAs) away from the target mRNAs (Gu et al., 2018; Wang et al., 2017; Xiong et al., 2018). Our bioinformatics analysis (Starbase) revealed that GAS5 harbors putative binding sites of miR-429, suggesting that GAS5 may play a role by binding to miR-429. miR-429 has been reported to be highly expressed in the lung tissues from LPS-induced ALI rats and can facilitate the LPS-induced inflammatory responses by targeting dual-specificity phosphatase 1 (DUSP1) (Xiao et al., 2015). Thus, we speculated that GAS5 might play a role in the LPS-induced ALI by acting as ceRNA for miR-429 to modulate DUSP1 expression.
In the present study, we detected the expression of GAS5, miR-429, and DUSP1 in lung tissues from LPS-induced ALI mice and LPS-treated murine alveolar epithelial cell line MLE-12. Furthermore, we investigated their interaction and effects on LPS-induced inflammation and apoptosis of MLE-12 cells.
Section snippets
ALI mice model
Male C57BL/6 mice (8–10 weeks old, weight 25–30 g) were raised in cages under a specific pathogen-free (SPF) environment (20–25 °C, 50–55% humidity, with adequate food and water) with a 12-h light-dark cycle. After acclimation for around one week, mice were randomly divided into two groups (n = 10/group): The normal group and ALI group. To establish the murine model of ALI, LPS (5 mg/kg, O111: B4 from Escherichia coli; Sigma-Aldrich, St. Louis, MO, USA) in 50 μl sterile saline was intratracheally
GAS5 and DUSP1 expression were decreased, whereas miR-429 expression was increased in ALI mice
Compared with the normal group, the expression of GAS5 in the lung tissues from mice in the ALI group was significantly decreased (Fig. 1A). In contrast, miR-429 expression in the ALI group was notably higher than that in the normal group (Fig. 1B). Furthermore, DUSP1 expression was significantly decreased in the ALI group compared with the normal group, both at mRNA (Fig. 1C) and protein levels (Fig. 1D).
LPS treatment decreased GAS5 and DUSP1 expression while it increased miR-429 expression in MLE-12 cells
Compared with the control group, GAS5 expression in the LPS-treated MLE-12 cells was
Discussion
ALI is a life-threatening syndrome with high rates of morbidity and mortality. LPS is an important pathogenic factor in ALI and has been widely used to induce ALI characterized by excessive uncontrolled inflammation and apoptosis of alveolar epithelial cells both in vivo and in vitro (Jiang et al., 2018; Ju et al., 2018; Lei et al., 2018a; Li et al., 2018e). Considerable evidence has emerged to suggest that pro-inflammatory cytokines, notably TNF-α, IL-1β and IL-6, play critical roles in the
Conclusions
In conclusion, our findings first revealed that GAS5 acted as a ceRNA by sponging miR-429 to facilitate DUSP1 expression, and thereby suppressed inflammatory responses and apoptosis of alveolar epithelial cell MLE-12 (Fig. 7). These findings suggest that GAS5 might serve as a potential therapeutic target for the treatment of ALI.
Declaration of Competing Interest
The authors declare no c.onflicts of interest.
Acknowledgements
None declared.
References (23)
- et al.
Growth arrest specific transcript 5 in tumorigenesis process: an update on the expression pattern and genomic variants
Biomed. Pharmacother.
(2019) Cordycepin inhibits LPS-induced acute lung injury by inhibiting inflammation and oxidative stress
Eur. J. Pharmacol.
(2018)Long non-coding RNA CASC2 improved acute lung injury by regulating miR-144-3p/AQP1 axis to reduce lung epithelial cell apoptosis
Cell Biosci.
(2018)Sodium butyrate alleviates LPS-induced acute lung injury in mice via inhibiting HMGB1 release
Int. Immunopharmacol.
(2018)Acute lung injury: a clinical and molecular review
Arch. Pathol. Lab. Med.
(2016)Knockdown of LncRNA MALAT1 contributes to the suppression of inflammatory responses by up-regulating miR-146a in LPS-induced acute lung injury
Connect. Tissue Res.
(2018)Upregulation of long noncoding RNA GAS5 inhibits lung cancer cell proliferation and metastasis via miR-205/PTEN Axis
Med. Sci. Monit.
(2019)Intranasal application of budesonide attenuates lipopolysaccharide-induced acute lung injury by suppressing nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 inflammasome activation in mice
J Immunol Res
(2019)Potential effects of medicinal plants and secondary metabolites on acute lung injury
Biomed. Res. Int.
(2013)Effect of the LncRNA GAS5-MiR-23a-ATG3 Axis in regulating autophagy in patients with breast cancer
Cell. Physiol. Biochem.
(2018)
Protective and therapeutic effects of Engeletin on LPS-induced acute lung injury
Inflammation.
Cited by (31)
Role of genetically engineered mesenchymal stem cell exosomes and LncRNAs in respiratory diseases treatment
2024, Pathology Research and PracticeLncRNA GAS5 suppresses inflammatory responses by inhibiting HMGB1 release via miR-155-5p/SIRT1 axis in sepsis
2023, European Journal of PharmacologyLong non-coding RNA (lncRNA): A potential therapeutic target in acute lung injury
2022, Genes and DiseasesUSP18 mitigates lipopolysaccharide-induced oxidative stress and inflammation in human pulmonary microvascular endothelial cells through the TLR4/NF-κB/ROS signaling
2021, Toxicology in VitroCitation Excerpt :Acute lung injury (ALI) is the injury of alveolar epithelial cells and pulmonary microvascular endothelial cells (PMVECs) caused by multiple causes such as infection, trauma, and shock (Li and Liu, 2020; Wang et al., 2019).