METTL3 aggravates cell damage induced by Streptococcus pneumoniae via the NEAT1/CTCF/MUC19 axis.

Disruption of the alveolar barrier can trigger acute lung injury. This study elucidated the association of methyltransferase-like 3 (METTL3) with Streptococcus pneumoniae (SP)-induced apoptosis and inflammatory injury of alveolar epithelial cells (AECs). AECs were cultured and then infected with SP. Furthermore, the expression of METTL3, interleukin (IL)-10, IL-6, tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1), mucin 19 (MUC19), N6-methyladenosine (m6A), and NEAT1 after m6A modification were detected by qRT-PCR, Western blot, and enzyme-linked immunosorbent, m6A quantification, and methylated RNA immunoprecipitation-qPCR analyses, respectively. Moreover, the subcellular localization of NEAT1 was analyzed by nuclear/cytosol fractionation assay, and the binding between NEAT1 and CCCTC-binding factor (CTCF) was also analyzed. The results of this investigation revealed that SP-induced apoptosis and inflammatory injury in AECs and upregulated METTL3 expression. In addition, the downregulation of METTL3 alleviated apoptosis and inflammatory injury in AECs. METTL3-mediated m6A modification increased NEAT1 and promoted its binding with CTCF to facilitate MUC19 transcription. NEAT1 or MUC19 overexpression disrupted their protective role of silencing METTL3 in AECs, thereby increasing apoptosis and inflammatory injury. In conclusion, this is the first study to suggest that METTL3 aggravates SP-induced cell damage via the NEAT1/CTCF/MUC19 axis.

Periostin mediates cigarette smoke extract-induced proliferation and migration in pulmonary arterial smooth muscle cells.

Cigarette smoking is an important risk factor for pulmonary arterial hypertension (PAH). Pulmonary arterial smooth muscle cells (PASMCs) play a critical role in the pathogenesis of PAH-associated arterial remodeling. This study was done to explore the expression and biological roles of periostin in PASMCs following exposure to cigarette smoke extract (CSE). PASMCs were exposed to different concentrations of CSE and tested for gene expression and reactive oxygen species (ROS) production. PASMCs were incubated with recombinant periostin protein or transfected with small interfering RNA targeting periostin before CSE exposure and then examined for cell proliferation and migration. Compared to control cells, exposure to CSE led to a significant upregulation of periostin. Pretreatment with 5mM N-acetyl-l-cysteine (an inhibitor of ROS formation) or 10µM U0126 (an inhibitor of ERK1/2) significantly prevented the induction of periostin in CSE-treated PASMCs. The addition of recombinant periostin protein significantly enhanced the proliferation and migration of PASMCs. In contrast, knockdown of endogenous periostin counteracted the proliferation and migration of PASMCs induced by CSE treatment. In conclusion, CSE induces the expression of periostin in PASMCs via promotion of ROS and activation of ERK1/2. Periostin mediates the effects of CSE on PASMC proliferation and migration. These findings warrant further exploration of the roles of periostin in cigarette smoking-associated pulmonary arterial remodeling.