Tschumperlin, Daniel

Abstract Lung fibrosis, including idiopathic pulmonary fibrosis (IPF), represents a spectrum of progressive interstitial lung diseases characterized by disrupted epithelial repair, fibroblast activation, and excess extracellular matrix accumulation. A central feature of fibrotic progression is the loss of alveolar type 2 epithelial (AT2) cell identity and the emergence of aberrant transitional states that fail to support normal regeneration. Based on our re-analysis of multiple publicly available scRNA-seq datasets from the IPF Cell Atlas, S100A2 expression is tightly associated with basal-like reprogramming of AT2 cells and is a top upregulated gene at both mRNA and protein levels in IPF lungs. Furthermore, scRNA-seq data from human lung organoid models reveal that AT2 cells co-cultured with fibroblasts acquire a basal-like phenotype and express high levels of S100A2. Functionally, overexpression of S100A2 in human iPSC-derived lung alveolar epithelial type 2 (iAT2) cells leads to loss of AT2 cellular identity, increased generation of reactive oxygen species, and activation of RAGE signaling pathway. We demonstrate that pharmacologic inhibition of RAGE using Azeliragon preserves AT2 cell populations, associated with reduced oxidative stress in iAT2 cells, and significantly attenuates collagen deposition in bleomycin-induced lung fibrosis models. Collectively, our results indicate that S100A2 is a key driver of epithelial dysfunction in lung fibrosis, promoting loss of AT2 identity, aberrant basal fate acquisition, and persistent epithelial injury. Targeting the unrecognized S100A2–RAGE pathway may offer a new therapeutic strategy to restore epithelial homeostasis in lung fibrosis.

Abstract Human genomic studies link reduced CUB domain-containing protein 1 (CDCP1) expression with myocardial recovery in heart failure. While CDCP1 regulates cardiac fibroblast proliferation in vitro, it’s in vivo role in cardiac fibrosis remains unclear. Using a Cdcp1 -knockout (KO) angiotensin II/phenylephrine mouse model, we show that Cdcp1 deletion reduces echocardiographic left ventricular mass, histologic cardiac fibrosis, and pro-fibrotic gene expression, along with decreased fibroblast activation and inflammatory markers. Spatial transcriptomics identified a pressure overload–expanded fibroblast subpopulation enriched for growth factor and TGF-β signaling (FB5), which was markedly attenuated in Cdcp1 -KO hearts, alongside reduction of a pro-inflammatory cardiomyocyte subtype (CM4). Complementary studies in human ventricular fibroblasts demonstrate that CDCP1 knockdown reduced extracellular matrix gene expression and collagen I deposition. These findings establish CDCP1 as a regulator of cardiac fibrotic remodeling in vivo and open avenues for its further investigation as a potential therapeutic target.

Nuclear translocation of mothers against decapentaplegic homolog 2/3 (SMAD2/3), core transcription factors of transforming growth factor β (TGF‐β) signaling, is critical for hepatic stellate cell (HSC) differentiation into metastasis‐promoting myofibroblasts. SMAD2/3 have multiple coactivators, including WW domain‐containing transcription regulator protein 1 (WWTR1 or TAZ) and p300 acetyltransferase. In the nucleus, TAZ binds to SMAD2/3 to prevent SMAD2/3 nuclear export. However, how TAZ and SMAD2/3 enter the nucleus remains poorly understood because neither contains a nuclear localization signal (NLS), an amino acid sequence tagging proteins for nuclear transport. p300 is an NLS‐containing large scaffold protein, so we hypothesized that SMAD2/3 and TAZ may undergo nuclear import through complexing with p300. Coimmunoprecipitation, immunofluorescence, and nuclear fractionation assays revealed that TGF‐β1 promoted binding of SMAD2/3 and TAZ to p300 and that p300 inactivation disrupted TGF‐β1‐mediated SMAD2/3 and TAZ nuclear accumulation. Deleting the p300 NLS blocked TGF‐β1‐induced SMAD2/3 and TAZ nuclear transport. Consistently, p300 inactivation suppressed TGF‐β1‐mediated HSC activation and transcription of genes encoding tumor‐promoting factors, such as connective tissue growth factor, Tenascin C, Periostin, platelet‐derived growth factor C, and fibroblast growth factor 2, as revealed by microarray analysis. Chromatin immunoprecipitation‐real‐time quantitative PCR showed that canonical p300‐mediated acetylation of histones also facilitated transcription in response to TGF‐β1 stimulation. Interestingly, although both TGF‐β1‐mediated and stiffness‐mediated HSC activation require p300, comparison of gene expression data sets revealed that transcriptional targets of TGF‐β1 were distinct from those of stiffness‐p300 mechanosignaling. Lastly, in tumor/HSC coinjection and intrasplenic tumor injection models, targeting p300 of activated‐HSC/myofibroblasts by C646, short hairpin RNA, or cre ‐mediated gene disruption reduced tumor and liver metastatic growth in mice. Conclusion: p300 facilitates TGF‐β1‐stimulated HSC activation by both noncanonical (cytoplasm‐to‐nucleus shuttle for SMAD2/3 and TAZ) and canonical (histone acetylation) mechanisms. p300 is an attractive target for inhibiting HSC activation and the prometastatic liver microenvironment.