Histone methyltransferase SETDB1 inhibits TGF-ß-induced epithelial-mesenchymal transition in pulmonary fibrosis by regulating SNAI1 expression and the ferroptosis signaling pathway.

The epithelial-mesenchymal transition (EMT) is an important pathological process in the occurrence of pulmonary fibrosis. Changes in histone methylation modifications of key genes play an important role in this process. As a histone methyltransferase, the regulatory mechanism and role of SET domain bifurcated 1 (SETDB1) in pulmonary fibrosis remain unclear. We found that SETDB1 inhibited EMT and that cells attenuated the expression of SETDB1 to relieve this inhibition during transforming growth factor-ß (TGF-ß)-induced EMT. Silencing SETDB1 expression significantly enhanced the mesenchymal phenotype induced by TGF-ß and the expression and deposition of fibronectin and significantly reduced the expression of E-cadherin. The decrease in E-cadherin expression and the induction of EMT led to increased lipid reactive oxygen species (ROS) and ferrous ions, which induced ferroptosis. Chromatin immunoprecipitation (ChIP) results showed that SETDB1 regulates the expression of Snai1 by catalyzing the histone H3 lysine 9 trimethylation (H3K9me3) of Snai1, the main transcription factor that initiates the process of EMT, and thus, indirectly regulates E-cadherin. Surprisingly, when examining the effect of overexpressed SETDB1 on EMT, we found that overexpressed SETDB1 alleviated EMT and also caused ferroptosis. We suggest that the overexpression of SETDB1 partially reverses the mesenchymal phenotype to an epithelial state, while those cells that fail to reverse are depleted by ferroptosis. In conclusion, the histone methylase SETDB1 regulates Snai1 epigenetically, driving EMT gene reprogramming and ferroptosis in response to TGF-ß. However, there are unexplored links between the epigenetic reprogramming and transcriptional processes that regulate EMT in a TGF-ß-dependent manner.

Cytotoxicity analysis of biomass combustion particles in human pulmonary alveolar epithelial cells on an air-liquid interface/dynamic culture platform.

BACKGROUND: Exposure to indoor air pollution from solid fuel combustion is associated with lung diseases and cancer. This study investigated the cytotoxicity and molecular mechanisms of biomass combustion-derived particles in human pulmonary alveolar epithelial cells (HPAEpiC) using a platform that combines air-liquid interface (ALI) and dynamic culture (DC) systems. METHODS: HPAEpiC were cultured on the surface of polycarbonate (PC) membranes on the ALI-DC platform. The cells were sprayed with an aerosolized solution of biomass combustion soluble constituents (BCSCs) and simultaneously nourished with culture medium flowing beneath the permeable PC membranes. The ALI-DC method was compared with the traditional submerged culture approach. BCSC particle morphology and dosages deposited on the chip were determined for particle characterization. Flow cytometry, scanning electron microscopy, and transmission electron microscopy were used to investigate the apoptosis rate of HPAEpiC and changes in the cell ultrastructure induced by BCSCs. Additionally, the underlying apoptotic pathway was examined by determining the protein expression levels by western blotting. RESULTS: Scanning electron microscope images demonstrated that the sample processing and delivering approach of the ALI-DC platform were suitable for pollutant exposure. Compared with the submerged culture method, a significant decline in cell viability and increase in apoptosis rate was observed after BCSC exposure on the ALI-DC platform, indicating that the ALI-DC platform is a more sensitive system for investigating cytotoxicity of indoor air pollutants in lung cells. The morphology and ultrastructure of the cells were damaged after exposure to BCSCs, and the p53 pathway was activated. The Bcl-2/Bax ratio was reduced, upregulating caspase-9 and caspase-3 expression and subsequently inducing apoptosis of HPAEpiC. The addition of N-acetyl cysteine antioxidant significantly alleviated the cytotoxicity induced by BCSCs. CONCLUSION: A novel ALI-DC platform was developed to study the cytotoxicity of air pollutants on lung cells. Using the platform, we demonstrated that BCSCs could damage the mitochondria, produce reactive oxygen species, and activate p53 in HPAEpiC, ultimately inducing apoptosis.

Role of the CASZ1 transcription factor in tissue development and disease.

The zinc finger transcription factor gene, CASZ1/Castor (Castor zinc finger 1), initially identified in Drosophila, plays a critical role in neural, cardiac, and cardiovascular development, exerting a complex, multifaceted influence on cell fate and tissue morphogenesis. During neurogenesis, CASZ1 exhibits dynamic expression from early embryonic development to the perinatal period, constituting a key regulator in this process. Additionally, CASZ1 controls the transition between neurogenesis and gliomagenesis. During human cardiovascular system development, CASZ1 is essential for cardiomyocyte differentiation, cardiac morphogenesis, and vascular morphology homeostasis and formation. The deletion or inactivation of CASZ1 mutations can lead to human developmental diseases or tumors, including congenital heart disease, cardiovascular disease, and neuroblastoma. CASZ1 can be used as a biomarker for disease prevention and diagnosis as well as a prognostic indicator for cancer. This review explores the unique functions of CASZ1 in tissue morphogenesis and associated diseases, offering new insights for elucidating the molecular mechanisms underlying diseases and identifying potential therapeutic targets for disease prevention and treatment.

Network Pharmacology-Based Mechanistic Investigation of Jinshui Huanxian Formula Acting on Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic respiratory disease with high incidence, morbidity, and mortality rates. Jinshui Huanxian formula (JHF) is an empirical formula that targets the pathogenesis of lung-kidney qi deficiency and phlegm-blood stasis in pulmonary fibrosis (PF). The purpose of this study was to explore JHF's potential pharmacological mechanisms in IPF therapy using network intersection analysis. JHF's primary active components and corresponding target genes were predicted using various databases. Two sets of IPF disease genes were obtained from the DisGeNET and GEO databases and two sets of IPF drug targets were collected. The disease and drug target genes were analyzed. The JHF target genes that intersected with IPF's differentially expressed genes were identified to predict JHF's targets of action in IPF. The functions and pathways of predicted targets acting on IPF were analyzed using the DAVID and KEGG pathway databases. Finally, the resulting drug target mechanisms were validated in a rat model of PF. The initial analyses identified 494 active compounds and 1,304 corresponding targets for JHF. The intersection analysis revealed four common genes for the JHF targets, IPF disease, and anti-IPF drugs in the KEGG database. Furthermore, these genes were targeted by several JHF compounds. Seventy-two JHF targets were closely related to IPF, which suggests that they are therapeutically relevant. Target screening revealed that they regulate IPF through 18 pathways. The targets' molecular functions included regulation of oxidoreductase activity, kinase regulator activity, phosphotransferase activity, and transmembrane receptor protein kinase activity. In vivo experiments showed that JHF alleviated the degree of PF, including decreases in collagen deposition and epithelial-mesenchymal transition. This study systematically explored JHF's mechanisms to identify the specific target pathways involved in IPF. The generated pharmacological network, paired with in vivo validation, elucidates the potential roles and mechanisms of JHF in IPF therapy.

An in vitro cytotoxicities comparison of 16 priority polycyclic aromatic hydrocarbons in human pulmonary alveolar epithelial cells HPAEpiC.

In present study, we compared for the first time the cytotoxicities of the 16 priority polycyclic aromatic hydrocarbons (PAHs) in human pulmonary alveolar epithelial cells HPAEpiC. Moreover, we examined the effects of each PAH on oxidative stress (SOD, GSH, and ROS), cell viability, extracellular LDH, and apoptosis. The 16 priority PAHs were classified into four levels of cytotoxicity: (1) high cytotoxicity, BkF, BaP, and DBA; (2) moderate cytotoxicity, BbF, IND, BghiP, BaA, and CHR; (3) low cytotoxicity, PA, FL, and Pyr; and (4) mild cytotoxicity, Nap, AcPy, Acp, Flu, and Ant. Most of the PAHs showed benzene-ring-related cytotoxicity, except PA with 3-ring structure, cytotoxicity of which is similar to those of FL and Pyr with 4-ring structure. Results indicated the need for more studies on DBA, IND, and BghiP, among others, which are rarely investigated. PA, FL, and Pyr with little carcinogenicity should also be evaluated. This study will provide useful references for studies on the effects of PAHs on different cells or animal models.

Cytotoxicity analysis of indoor air pollution from biomass combustion in human keratinocytes on a multilayered dynamic cell culture platform.

Skin tissue is the first barrier against ambient harmful matter and has direct contact with indoor air pollutants. Nevertheless, a comprehensive understanding of cytotoxicity of indoor air pollution on skin cells is insufficiently clear. Herein, for the first time a multilayered dynamic cell culture platform was established to study the cytotoxicity of indoor air pollutant from biomass combustion in human skin keratinocytes. The platform consisted of seven repetitive polydimethylsiloxane modules carrying six pieces of polycarbonate membrane between them as substrate for cell growth to realize the simultaneous dynamic culture of 12 layers of keratinocytes. After exposure to biomass combustion soluble constituents (BCSCs), cell viability under microfluidic platform conditions declined more significantly, and apoptosis rates increased more obviously compared with well plate conditions. Transmission electron microscope showed that keratinocyte microstructures displayed obvious signs of cellular damage. Our study confirmed that the nuclear factor of kappa B (NF-κB) signaling pathway was activated, which significantly increased the Bax/Bcl-2 ratio and tumor necrosis factor-alpha and interleukin 6 expression, indicating that NF-κB signaling pathway was the major factor in BCSCs-induced cytotoxicity. These findings offer an insight into the mechanism of BCSCs-induced cytotoxicity in keratinocytes and provide a theoretical basis for future studies on skin cells.