TGF-β-induced α-SMA expression is mediated by C/EBPβ acetylation in human alveolar epithelial cells

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse (POP) involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity, and vaginal structure is an essential factor. In POP, the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and functions. The intricate etiology of POP and the prohibition of transvaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy development. Human umbilical cord mesenchymal stromal cells (hucMSCs) present limitations, but their exosomes (hucMSC-Exo) are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix remodeling.

AIM

To investigate the effects of hucMSC-Exo on the functions of primary vaginal fibroblasts and to elucidate the underlying mechanism involved.

METHODS

Human vaginal wall collagen content was assessed by Masson's trichrome and Sirius blue staining. Gene expression differences in fibroblasts from patients with and without POP were assessed via RNA sequencing (RNA-seq). The effects of hucMSC-Exo on fibroblasts were determined via functional experiments in vitro. RNA-seq data from fibroblasts exposed to hucMSC-Exo and microRNA (miRNA) sequencing data from hucMSC-Exo were jointly analyzed to identify effective molecules.

RESULTS

In POP, the vaginal wall exhibited abnormal collagen distribution and reduced fibroblast 1 quality and quantity. Treatment with 4 or 6 μg/mL hucMSC-Exo suppressed inflammation in POP group fibroblasts, stimulated primary fibroblast growth, and elevated collagen I (Col1) production in vitro. High-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11 (MMP11) expression.

CONCLUSION

HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in vitro. Abundant miRNAs in hucMSC-Exo targeted and downregulated MMP11 expression. HucMSC-Exo-based therapy may be ideal for safely and effectively treating POP.

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse (POP) involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity, and vaginal structure is an essential factor. In POP, the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and functions. The intricate etiology of POP and the prohibition of transvaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy development. Human umbilical cord mesenchymal stromal cells (hucMSCs) present limitations, but their exosomes (hucMSC-Exo) are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix remodeling.

AIM

To investigate the effects of hucMSC-Exo on the functions of primary vaginal fibroblasts and to elucidate the underlying mechanism involved.

METHODS

Human vaginal wall collagen content was assessed by Masson’s trichrome and Sirius blue staining. Gene expression differences in fibroblasts from patients with and without POP were assessed via RNA sequencing (RNA-seq). The effects of hucMSC-Exo on fibroblasts were determined via functional experiments in vitro. RNA-seq data from fibroblasts exposed to hucMSC-Exo and microRNA (miRNA) sequencing data from hucMSC-Exo were jointly analyzed to identify effective molecules.

RESULTS

In POP, the vaginal wall exhibited abnormal collagen distribution and reduced fibroblast 1 quality and quantity. Treatment with 4 or 6 μg/mL hucMSC-Exo suppressed inflammation in POP group fibroblasts, stimulated primary fibroblast growth, and elevated collagen I (Col1) production in vitro. High-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11 (MMP11) expression.

CONCLUSION

HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in vitro. Abundant miRNAs in hucMSC-Exo targeted and downregulated MMP11 expression. HucMSC-Exo-based therapy may be ideal for safely and effectively treating POP.

Current state of signaling pathways associated with the pathogenesis of idiopathic pulmonary fibrosis

Idiopathic Pulmonary Fibrosis (IPF) represents a chronic and progressive pulmonary disorder distinguished by a notable mortality rate. Despite the elusive nature of the pathogenic mechanisms, several signaling pathways have been elucidated for their pivotal roles in the progression of this ailment. This manuscript aims to comprehensively review the existing literature on the signaling pathways linked to the pathogenesis of IPF, both within national and international contexts. The objective is to enhance the comprehension of the pathogenic mechanisms underlying IPF and offer a scholarly foundation for the advancement of more efficacious therapeutic strategies, thereby fostering research and clinical practices within this domain.

Excess glucose alone depress young mesenchymal stromal/stem cell osteogenesis and mitochondria activity within hours/days via NAD+/SIRT1 axis

BACKGROUND

The impact of global overconsumption of simple sugars on bone health, which peaks in adolescence/early adulthood and correlates with osteoporosis (OP) and fracture risk decades, is unclear. Mesenchymal stromal/stem cells (MSCs) are the progenitors of osteoblasts/bone-forming cells, and known to decrease their osteogenic differentiation capacity with age. Alarmingly, while there is correlative evidence that adolescents consuming greatest amounts of simple sugars have the lowest bone mass, there is no mechanistic understanding on the causality of this correlation.

METHODS

Bioinformatics analyses for energetics pathways involved during MSC differentiation using human cell information was performed. In vitro dissection of normal versus high glucose (HG) conditions on osteo-/adipo-lineage commitment and mitochondrial function was assessed using multi-sources of non-senescent human and murine MSCs; for in vivo validation, young mice was fed normal or HG-added water with subsequent analyses of bone marrow CD45- MSCs.

RESULTS

Bioinformatics analyses revealed mitochondrial and glucose-related metabolic pathways as integral to MSC osteo-/adipo-lineage commitment. Functionally, in vitro HG alone without differentiation induction decreased both MSC mitochondrial activity and osteogenesis while enhancing adipogenesis by 8 h' time due to depletion of nicotinamide adenine dinucleotide (NAD+), a vital mitochondrial co-enzyme and co-factor to Sirtuin (SIRT) 1, a longevity gene also involved in osteogenesis. In vivo, HG intake in young mice depleted MSC NAD+, with oral NAD+ precursor supplementation rapidly reversing both mitochondrial decline and osteo-/adipo-commitment in a SIRT1-dependent fashion within 1 ~ 5 days.

CONCLUSIONS

We found a surprisingly rapid impact of excessive glucose, a single dietary factor, on MSC SIRT1 function and osteogenesis in youthful settings, and the crucial role of NAD+-a single molecule-on both MSC mitochondrial function and lineage commitment. These findings have strong implications on future global OP and disability risks in light of current worldwide overconsumption of simple sugars.

Midkine promotes renal fibrosis by stabilizing C/EBPβ to facilitate endothelial-mesenchymal transition

Numerous myofibroblasts are arisen from endothelial cells (ECs) through endothelial to mesenchymal transition (EndMT) triggered by TGF-β. However, the mechanism of ECs transforms to a different subtype, or whether there exists an intermediate state of ECs remains unclear. In present study, we demonstrate Midkine (MDK) mainly expressed by CD31 + ACTA2+ECs going through partial EndMT contribute greatly to myofibroblasts by spatial and single-cell transcriptomics. MDK is induced in TGF-β treated ECs, which upregulates C/EBPβ and increases EndMT genes, and these effects could be reversed by siMDK. Mechanistically, MDK promotes the binding ability of C/EBPβ with ACTA2 promoter by stabilizing the C/EBPβ protein. In vivo, knockout of Mdk or conditional knockout of Mdk in ECs reduces EndMT markers and significantly reverses fibrogenesis. In conclusion, our study provides a mechanistic link between the induction of EndMT by TGF-β and MDK, which suggests that blocking MDK provides potential therapeutic strategies for renal fibrosis.

Identifying a survival-associated cell type based on multi-level transcriptome analysis in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a five-year survival rate of less than 40%. There is significant variability in survival time among IPF patients, but the underlying mechanisms for this are not clear yet.

METHODS AND RESULTS

We collected single-cell RNA sequence data of 13,223 epithelial cells taken from 32 IPF patients and bulk RNA sequence data from 456 IPF patients in GEO. Based on unsupervised clustering analysis at the single-cell level and deconvolution algorithm at bulk RNA sequence data, we discovered a special alveolar type 2 cell subtype characterized by high expression of CCL20 (referred to as ATII-CCL20), and found that IPF patients with a higher proportion of ATII-CCL20 had worse prognoses. Furthermore, we uncovered the upregulation of immune cell infiltration and metabolic functions in IPF patients with a higher proportion of ATII-CCL20. Finally, the comprehensive decision tree and nomogram were constructed to optimize the risk stratification of IPF patients and provide a reference for accurate prognosis evaluation.

CONCLUSIONS

Our study by integrating single-cell and bulk RNA sequence data from IPF patients identified a special subtype of ATII cells, ATII-CCL20, which was found to be a risk cell subtype associated with poor prognosis in IPF patients. More importantly, the ATII-CCL20 cell subtype was linked with metabolic functions and immune infiltration.

The protease activated receptor 2 - CCAAT/enhancer-binding protein beta - SerpinB3 axis inhibition as a novel strategy for the treatment of non-alcoholic steatohepatitis

OBJECTIVE

The serine protease inhibitor SerpinB3 has been described as critical mediator of liver fibrosis and it has been recently proposed as an additional hepatokine involved in NASH development and insulin resistance. Protease Activated Receptor 2 has been identified as a novel regulator of hepatic metabolism. A targeted therapeutic strategy for NASH has been investigated, using 1-Piperidine Propionic Acid (1-PPA), since this compound has been recently proposed as both Protease Activated Receptor 2 and SerpinB3 inhibitor.

METHODS

The effect of SerpinB3 on inflammation and fibrosis genes was assessed in human macrophage and stellate cell lines. Transgenic mice, either overexpressing SerpinB3 or carrying Serpinb3 deletion and their relative wild type strains, were used in experimental NASH models. Subgroups of SerpinB3 transgenic mice and their controls were also injected with 1-PPA to assess the efficacy of this compound in NASH inhibition.

RESULTS

1-PPA did not present significant cell and organ toxicity and was able to inhibit SerpinB3 and PAR2 in a dose-dependent manner. This effect was associated to a parallel reduction of the synthesis of the molecules induced by endogenous SerpinB3 or by its paracrine effects both in vitro and in vivo, leading to inhibition of lipid accumulation, inflammation and fibrosis in experimental NASH. At mechanistic level, the antiprotease activity of SerpinB3 was found essential for PAR2 activation, determining upregulation of the CCAAT Enhancer Binding Protein beta (C/EBP-β), another pivotal regulator of metabolism, inflammation and fibrosis, which in turn determined SerpinB3 synthesis.

CONCLUSIONS

1-PPA treatment was able to inhibit the PAR2 - C/EBP-β - SerpinB3 axis and to protect from NASH development and progression, supporting the potential use of a similar approach for a targeted therapy of NASH.

[C/EBPβ mediates expressions of downstream inflammatory factors of the tumor necrosis factor-α signaling pathway in renal tubular epithelial cells with NPHP1 knockdown]

OBJECTIVE

To explore the activation of tumor necrosis factor-α (TNF-α) signaling pathway and the expressions of the associated inflammatory factors in NPHP1-defective renal tubular epithelial cells.

METHODS

A human proximal renal tubular cell (HK2) model of lentivirus-mediated NPHP1 knockdown (NPHP1KD) was constructed, and the expressions of TNF-α, p38, and C/EBPβ and the inflammatory factors CXCL5, CCL20, IL-1β, IL-6 and MCP-1 were detected using RT-qPCR, Western blotting or enzyme-linked immunosorbent assay. A small interfering RNA (siRNA) was transfected in wild-type and NPHP1KDHK2 cells, and the changes in the expressions of TNF-α, p38, and C/EBPβ and the inflammatory factors were examined.

RESULTS

NPHP1KDHK2 cells showed significantly increased mRNA expressions of TNF-α, C/EBPβ, CXCL5, IL-1β, and IL-6 (P < 0.05), protein expressions of phospho-p38 and C/EBPβ (P < 0.05), and IL-6 level in the culture supernatant (P < 0.05), and these changes were significantly blocked by transfection of cells with siRNA-C/EBPβ (P < 0.05).

CONCLUSION

TNF-α signaling pathway is activated and its associated inflammatory factors are upregulated in NPHP1KDHK2 cells, and C/EBPβ may serve as a key transcription factor to mediate these changes.

Epigenetic hallmarks in pulmonary fibrosis: New advances and perspectives

Epigenetics indicates that certain phenotypes of an organism can undergo heritable changes in the absence of changes in the genetic DNA sequence. Many studies have shown that epigenetic patterns play an important role in the lung and lung diseases. Pulmonary fibrosis (PF) is also a type of lung disease. PF is an end-stage change of a large group of lung diseases, characterized by fibroblast proliferation and massive accumulation of extracellular matrix, accompanied by inflammatory injury and histological destruction, that is, structural abnormalities caused by abnormal repair of normal alveolar tissue. It causes loss of lung function in patients with multiple complex diseases, leading to respiratory failure and subsequent death. However, current treatment options for IPF are very limited and no drugs have been shown to significantly prolong the survival of patients. Therefore, based on a systematic understanding of the disease mechanisms of PF, this review integrates the role of epigenetics in the development and course of PF, describes preventive and potential therapeutic targets for PF, and provides a theoretical basis for further exploration of the mechanisms of PF.

Ethanol-exposed lung fibroblasts cause airway epithelial barrier dysfunction

BACKGROUND

Chronic alcohol ingestion predisposes to lung injury and disrepair during sepsis. Our previous studies outlined roles for transforming growth factor-beta 1 (TGFβ1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in epithelial barrier homeostasis and how alcohol perturbs their expression and signaling. Here we hypothesize that ethanol-exposed lung fibroblasts (LF) are a source of dysregulated TGFβ1 and GM-CSF and thereby alter airway epithelial barrier function.

METHODS

Human or rat LF were cultured ± ethanol for 2 weeks and then co-cultured with human or rat airway epithelial cells (AEC) seeded on Transwell permeable supports. In selected groups, a TGFβ1 receptor type 1 (TGFβR1) inhibitor (SB431542) or a TGFβ1 neutralizing antibody was applied. Transepithelial electrical resistance (TER) was measured prior to co-culture and on day 5 of co-culture. AEC were then analyzed for the expression of selected tight junction and mesenchymal proteins, and transwell membranes were analyzed by immunofluorescence microscopy for ZO-1 expression and localization. TGFβ1 and GM-CSF levels in conditioned media from the co-cultures were quantified by ELISA.

RESULTS

AEC co-cultured with ethanol-exposed LF (ELF) showed a significant reduction in TER and corresponding decreases in ZO-1 expression, whereas collagen type 1A1 and α-smooth muscle actin protein expression were increased. In parallel, in conditioned media from the ELF + AEC co-cultures, activated TGFβ1 levels increased and GM-CSF levels decreased. Notably, all the effects of ELF on the AEC were prevented by blocking TGFβ1 activity.

CONCLUSIONS

Prior ethanol exposure to LF induces barrier dysfunction in naive AEC in a paracrine fashion through activation of TGFβ1 signaling and suppression of GM-CSF. These experimental findings provide a potential mechanism by which chronic alcohol ingestion impairs airway epithelial integrity and renders individuals susceptible to lung injury.

MiR-155-5p Elevated by Ochratoxin A Induces Intestinal Fibrosis and Epithelial-to-Mesenchymal Transition through TGF-β Regulated Signaling Pathway In Vitro and In Vivo

Ochratoxin A (OTA) is a mycotoxin that induces fibrosis and epithelial-to-mesenchymal transitions (EMT) in kidneys and livers. It enters our bodies through food consumption, where it is absorbed in the intestines. However, the impact of OTA on the intestines is yet to be studied. MicroRNA (miRNAs) are small non-coding single-stranded RNAs that block the transcription of specific mRNAs and are, therefore, involved in many biochemical processes. Our findings indicate that OTA can induce EMT and intestinal fibrosis both in vivo and in vitro. This study examines the impact of OTA on intestinal toxicity and the role of miRNAs in this process. Following OTA treatment, miR-155-5p was the most elevated miRNA by next-generation sequencing. Our research showed that OTA increased miR-155-5p levels through transforming growth factor β (TGF-β), leading to the development of intestinal fibrosis and EMT. Additionally, the study identified that the modulation of TGF-β and miR-155-5p by OTA is linked to the inhibition of CCAAT/enhancer-binding protein β (C/EBPβ) and Smad2/3 accumulation in the progression of intestinal fibrosis.

A systems biology investigation of curcumin potency against TGF-β-induced EMT signaling in lung cancer

Curcumin (diferuloylmethane) is bioactive phenolic compound which exerts diverse antimetastatic effect. Several studies have reported the antimetastatic effect of curcumin by its ability to modulate the epithelial-to-mesenchymal transition (EMT) process in different cancers, but underlying molecular mechanism is poorly understood. EMT is a highly conserved biological process in which epithelial cells acquire mesenchymal-like characteristics by losing their cell-cell junctions and polarity. As a consequence, deviation in cellular mechanism leads to cancer metastasis and thereby death. In this perspective, we explored the antimetastatic potential and mechanism of curcumin on the EMT process by establishing in vitro EMT model in lungs cancer (A549) cells induced by TGF-β1. Our results showed that curcumin mitigates EMT by regulating the expression of crucial mesenchymal markers such as MMP2, vimentin and N-cadherin. Besides, the transcriptional analysis revealed that the curcumin treatment differentially regulated the expression of 75 genes in NanoString nCounter platform. Further protein-protein interaction network and clusters analysis of differentially expressed genes revealed their involvement in essential biological processes that plays a key role during EMT transition. Altogether, the study provides a comprehensive overview of the antimetastatic potential of curcumin in TGF-β1-induced EMT in lung cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03360-7.

CCAAT/Enhancer-Binding Proteins in Fibrosis: Complex Roles Beyond Conventional Understanding

CCAAT/enhancer-binding proteins (C/EBPs) are a family of at least six identified transcription factors that contain a highly conserved basic leucine zipper domain and interact selectively with duplex DNA to regulate target gene expression. C/EBPs play important roles in various physiological processes, and their abnormal function can lead to various diseases. Recently, accumulating evidence has demonstrated that aberrant C/EBP expression or activity is closely associated with the onset and progression of fibrosis in several organs and tissues. During fibrosis, various C/EBPs can exert distinct functions in the same organ, while the same C/EBP can exert distinct functions in different organs. Modulating C/EBP expression or activity could regulate various molecular processes to alleviate fibrosis in multiple organs; therefore, novel C/EBPs-based therapeutic methods for treating fibrosis have attracted considerable attention. In this review, we will explore the features of C/EBPs and their critical functions in fibrosis in order to highlight new avenues for the development of novel therapies targeting C/EBPs.

MiR-192-5p Alleviated Fibrosis and Inflammatory Responses of Tendon Cells by Targeting NFAT5

Objective

To explore the effect of microRNA (miR)-192-5p on the inflammatory and fibrotic responses of tendon cells.

Methods

Tendon cells were treated with transforming growth factor-β1 (TGF-β1). The expression of miR-192-5p and nuclear factor of activated T cells 5 (NFAT5) in tendon cells were detected by RT-qPCR. The expressions of inflammatory and fibrosis-related factors were detected by RT-qPCR and Western blot. MiR-192-5p binds to NFAT5 targeting by TargetScan and dual-luciferase reporter gene assay. The expression of the NFAT5 gene was detected by RT-qPCR and Western blot. Detection of apoptosis in tendon cells by flow cytometry.

Results

MiR-192-5p was downregulated in tendon cells, and the expression level gradually decreased with the prolong of TGF-β1 treatment. The expression of NFAT5 increased with the treatment time of TGF-β1. The expression of miR-192-5p decreased collagen III (COLIII), α smooth muscle actin (α-SMA), matrix metalloproteinase- (MMP-) 1, and MMP-8 expression, thereby inhibiting TGF-β1-induced fibrosis in tendon cells. The expression of miR-192-5p decreased the expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β, thereby alleviating TGF-β1-induced inflammatory response and reduce apoptosis in tendon cells. NFAT5 is a direct target of miR-192-5p in tendon cells. The upregulation of NFAT5 reversed the effect of miR-192-5p on the fibrotic activity and inflammatory response of TGF-β1-stimulated tendon cells.

Conclusions

MiR-192-5p alleviates fibrosis and inflammatory responses of tendon cells by targeting NFAT5.

First Characterization of Human Dermal Fibroblasts Showing a Decreased Xylosyltransferase-I Expression Induced by the CRISPR/Cas9 System

BACKGROUND

Xylosyltransferases-I and II (XT-I and XT-II) catalyze the initial and rate limiting step of the proteoglycan (PG) biosynthesis and therefore have an import impact on the homeostasis of the extracellular matrix (ECM). The reason for the occurrence of two XT-isoforms in all higher organisms remains unknown and targeted genome-editing strategies could shed light on this issue.

METHODS

XT-I deficient neonatal normal human dermal fibroblasts were generated by using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated proteins (Cas) 9 system. We analyzed if a reduced XT-I activity leads to abnormalities regarding ECM-composition, myofibroblast differentiation, cellular senescence and skeletal and cartilage tissue homeostasis.

RESULTS

We successfully introduced compound heterozygous deletions within exon 9 of the XYLT1 gene. Beside XYLT1, we detected altered gene-expression levels of further, inter alia ECM-related, genes. Our data further reveal a dramatically reduced XT-I protein activity. Abnormal myofibroblast-differentiation was demonstrated by elevated alpha-smooth muscle actin expression on both, mRNA- and protein level. In addition, wound-healing capability was slightly delayed. Furthermore, we observed an increased cellular-senescence of knockout cells and an altered expression of target genes knowing to be involved in skeletonization.

CONCLUSION

Our data show the tremendous relevance of the XT-I isoform concerning myofibroblast-differentiation and ECM-homeostasis as well as the pathophysiology of skeletal disorders.

Regulation of epithelial-mesenchymal transition by protein lysine acetylation

The epithelial-mesenchymal transition (EMT) is a vital driver of tumor progression. It is a well-known and complex trans-differentiation process in which epithelial cells undergo morphogenetic changes with loss of apical-basal polarity, but acquire spindle-shaped mesenchymal phenotypes. Lysine acetylation is a type of protein modification that favors reversibly altering the structure and function of target molecules via the modulation of lysine acetyltransferases (KATs), as well as lysine deacetylases (KDACs). To date, research has found that histones and non-histone proteins can be acetylated to facilitate EMT. Interestingly, histone acetylation is a type of epigenetic regulation that is capable of modulating the acetylation levels of distinct histones at the promoters of EMT-related markers, EMT-inducing transcription factors (EMT-TFs), and EMT-related long non-coding RNAs to control EMT. However, non-histone acetylation is a post-translational modification, and its effect on EMT mainly relies on modulating the acetylation of EMT marker proteins, EMT-TFs, and EMT-related signal transduction molecules. In addition, several inhibitors against KATs and KDACs have been developed, some of which can suppress the development of different cancers by targeting EMT. In this review, we discuss the complex biological roles and molecular mechanisms underlying histone acetylation and non-histone protein acetylation in the control of EMT, highlighting lysine acetylation as potential strategy for the treatment of cancer through the regulation of EMT.

Histone methyltransferase SETDB1 inhibits TGF-β-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-β (TGF-β)-induced EMT. Silencing SETDB1 expression significantly enhanced the mesenchymal phenotype induced by TGF-β 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-β. However, there are unexplored links between the epigenetic reprogramming and transcriptional processes that regulate EMT in a TGF-β-dependent manner.

IPF-Fibroblast Erk1/2 Activity Is Independent from microRNA Cluster 17-92 but Can Be Inhibited by Treprostinil through DUSP1

Idiopathic pulmonary fibrosis (IPF) is a progressive terminal lung disease, and therapies aim to block fibrosis. Fibroblast proliferation is controlled by C/EBP-β, microRNA cluster 17-92 (miR17-92), and Erk1/2 mitogen-activated protein kinase. This study assessed the role of miR17-92 in IPF-fibroblast proliferation and its modification by treprostinil. Fibroblasts were isolated from eight IPF patients, five interstitial lung fibrosis patients, and seven control lungs. Fibroblasts were stimulated with TGF-β1 over 24 h. The miR17-92 expression was analyzed by RT-qPCR, and protein expression by Western blotting. TGF-β1 upregulated C/EBP-β in all fibroblasts, which was reduced by treprostinil in control-fibroblasts, but not in IPF-fibroblasts. Compared to controls, the guide strands miR-19a-3p, miR-19b-3p, miR-20a-5p, and miR-92a-3p, as well as the passenger strands miR-17-3p, miR-18-3p, miR-19a-1-5p, and miR-92a-5p were significantly increased in IPF-fibroblasts. In controls, TGF-β1 and treprostinil significantly reduced specific miR17-92 members. IPF-fibroblast proliferation was inhibited by treprostinil through increased expression of the Erk1/2 inhibitor DUSP1. These data suggest that proliferation control via miR17-92 and C/EBP-β is disrupted in IPF-fibroblasts. Therefore, the inhibition of early stages of signaling cascades or specific mitogen receptors might be less effective. However, the increased proliferation is sensitive to Erk1/2 inhibition by treprostinil-induced DUSP1.