Fibrosis, a process caused by excessive deposition of extracellular matrix (ECM), is a common cause and outcome of organ failure and even death. Researchers have made many efforts to understand the ...mechanism of fibrogenesis and to develop therapeutic strategies; yet, the outcome remains unsatisfactory. In recent years, advances in epigenetics, including chromatin remodeling, histone modification, DNA methylation, and noncoding RNA (ncRNA), have provided more insights into the fibrotic process and have suggested the possibility of novel therapy for organ fibrosis. In this review, we summarize the current research on the epigenetic mechanisms involved in organ fibrosis and their possible clinical applications.
Skin fibrosis, a pathological process featured by fibroblast activation and extracellular matrix (ECM) deposition, makes a significant contribution to morbidity. Studies have identified biomechanics ...as the central element in the complex network of fibrogenesis that drives the profibrotic feedback loop. In this study, we found that the acetylation of α‐tubulin at lysine 40 (K40) was augmented in fibrotic skin tissues. Further analysis showed that α‐tubulin acetylation is required for fibroblast activation, including contraction, migration, and ECM deposition. More importantly, we revealed that biomechanics‐induced upregulation of K40 acetylation promotes fibrosis by mediating mechanosensitive Yes‐associated protein S127 dephosphorylation and its cytoplasm nucleus shuttle. Furthermore, we demonstrated that the knockdown of α‐tubulin acetyltransferase 1 could rescue the K40 acetylation upregulation caused by increased matrix rigidity and ameliorate skin fibrosis both in vivo and in vitro. Herein, we highlight the critical role of α‐tubulin acetylation in matrix stiffness‐induced skin fibrosis and clarify a possible molecular mechanism. Our research suggests α‐tubulin acetylation as a potential target for drug design and therapeutic intervention.
Matrix stiffness-induced α‐tubulin acetylation is required for skin fibrosis formation.
Acetylated α‐tubulin at K40 promoted fibroblast activation by dephosphorylating Yes‐associated protein and maintaining its nuclear retention.
Downregulating K40 acetylation of α‐tubulin through knockdown of α‐tubulin acetyltransferase 1 could ameliorate fibrosis formation.
Fibrosis, a pathologic process featured by the excessive deposition of connective tissue components, can affect virtually every organ and has no satisfactory therapy yet. Fibrotic diseases are often ...associated with organ dysfunction which leads to high morbidity and mortality. Biomechanical stmuli and the corresponding cellular response havebeen identified in fibrogenesis, as the fibrotic remodeling could be seen as the incapacity to reestablish mechanical homeostasis: along with extracellular matrix accumulating, the physical property became more "stiff" and could in turn induce fibrosis. In this review, we provide a comprehensive overview of mechanoregulation in fibrosis, from initialing cellular mechanosensing to intracellular mechanotransduction and processing, and ends up in mechanoeffecting. Our contents are not limited to the cellular mechanism, but further expand to the disorders involved and current clinical trials, providing an insight into the disease and hopefully inspiring new approaches for the treatment of tissue fibrosis.
Re-epithelialization is a complex process during skin wound healing, and cell migration is an integral part of this phenomenon. Here we identified a role for LRG1 as a key regulator of epidermal ...keratinocyte migration where LRG1 acts via enhancement of HIF-1α stability. We showed that LRG1 is upregulated at murine skin wound edges and that addition of recombinant human LRG1 accelerates keratinocyte migration and skin wound healing. Furthermore, we identified transcription factor ELK3 as a downstream effector of LRG1. We confirmed that elevated ELK3 levels manipulated by LRG1 can promote cell migration through upregulation of HIF-1α stability. Because hyperglycemia complicatedly affects HIF-1α stability and activation, our findings provide insights into the molecular controls of wound-associated cell migration and identify potential therapeutic targets for the treatment of chronic diabetic wounds. In conclusion, we demonstrated that LRG1 promotes wound repair through keratinocyte migration and is important for normalization of an abnormal process of diabetic wound healing where HIF-1α stability is insufficient.
Pancreatic ductal adenocarcinoma (PDAC) shows a remarkable predilection for liver metastasis. Pro-oncogenic secretome delivery and trafficking via exosomes are crucial for pre-metastatic ...microenvironment formation and metastasis. This study aimed to explore the underlying mechanisms of how PDAC-derived exosomes (Pex) modulate the liver microenvironment and promote metastasis.
C57BL/6 mice were 'educated' by tail vein Pex injection. The intrasplenic injection liver metastasis and PDAC orthotopic transplantation models were used to evaluate liver metastasis. Stable cell lines CD44v6 (CD44 variant isoform 6) or C1QBP (complement C1q binding protein) knockdown or overexpression was established using lentivirus transfection or gateway systems. A total of 142 patients with PDAC in Huashan Hospital were retrospectively enrolled. Prognosis and liver metastasis were predicted using Kaplan-Meier survival curves and logistic regression models.
Pex tail vein injection induced the deposition of liver fibrotic extracellular matrix, which promoted PDAC liver metastasis. Specifically, the exosomal CD44v6/C1QBP complex was delivered to the plasma membrane of hepatic satellite cells (HSCs), leading to phosphorylation of insulin-like growth factor 1 signalling molecules, which resulted in HSC activation and liver fibrosis. Expression of Pex CD44v6 and C1QBP in PDAC patients with liver metastasis was significantly higher than in PDAC patients without liver metastasis, and simultaneous high expression of exosomal CD44v6 and C1QBP correlated with a worse prognosis and a higher risk of postoperative PDAC liver metastasis.
The Pex-derived CD44v6/C1QBP complex is essential for the formation of a fibrotic liver microenvironment and PDAC liver metastasis. Highly expressed exosomal CD44v6 and C1QBP are promising biomarkers for predicting prognosis and liver metastasis in patients with PDAC.
Wound healing is a process of cutaneous barrier reconstruction that occurs after skin injury and involves diverse cytokines and cell types. Similar to several deubiquitinating enzymes, ...ubiquitin-specific protease 15 (USP15) can remove ubiquitin chains from specific proteins to rescue them from degradation. However, the regulatory role of USP15 in wound healing remains unclear. We investigated the dynamic function of USP15 in wound healing. First, in USP15 knockout mice, we observed a significant delay in wound closure. In addition, inhibition of cell proliferation and migration was observed in USP15-silenced human dermal fibroblasts. Through RNA sequencing, it was revealed that the transforming growth factor-β (TGF-β) pathway was suppressed after USP15 knockdown. Furthermore, coimmunoprecipitation demonstrated that USP15 could interact with TGF-β receptor I and promote its deubiquitination, thereby maintaining TGF-β signaling pathway activity by enhancing TGF-β receptor I stability. These observations shed light on the function and mechanisms of USP15-mediated modulation of the TGF-β signaling pathway during wound healing, thus providing a novel potential target for the treatment of refractory wounds.
Obesity and its associated metabolic disorders such as diabetes, hepatic steatosis and chronic heart diseases are affecting billions of individuals. However there is no satisfactory drug to treat ...such diseases. In this study, we found that alisol A, a major active triterpene isolated from the Chinese traditional medicine Rhizoma Alismatis, could significantly attenuate high‐fat‐diet‐induced obesity. Our biochemical detection demonstrated that alisol A remarkably decreased lipid levels, alleviated glucose metabolism disorders and insulin resistance in high‐fat‐diet‐induced obese mice. We also found that alisol A reduced hepatic steatosis and improved liver function in the obese mice model.In addition, protein expression investigation revealed that alisol A had an active effect on AMPK/ACC/SREBP‐1c pathway. As suggested by the molecular docking study, such bioactivity of alisol A may result from its selective binding to the catalytic region of AMPK.Therefore, we believe that Alisol A could serve as a promising agent for treatment of obesity and its related metabolic diseases.
Transforming growth factor-β (TGF-β) signaling plays a key role in excessive fibrosis. As a class IIa family histone deacetylase (HDAC), HDAC5 shows a close relationship with TGF-β signaling and ...fibrosis. However, the effect and regulatory mechanism of HDAC5 in hypertrophic scar (HS) formation remain elusive. We show that HDAC5 was overexpressed in HS tissues and depletion of HDAC5 attenuated HS formation
and inhibited fibroblast activation
. HDAC5 knockdown (KD) significantly downregulated TGF-β1 induced Smad2/3 phosphorylation and increased Smad7 expression. Meanwhile, Smad7 KD rescued the Smad2/3 phosphorylation downregulation and scar hyperplasia inhibition mediated by HDAC5 deficiency. Luciferase reporter assays and ChIP-qPCR assays revealed that HDAC5 interacts with myocyte enhancer factor 2A (MEF2A) suppressing MEF2A binding to the Smad7 promoter region, which results in Smad7 promoter activity repression. HDAC4/5 inhibitor, LMK235, significantly alleviated hypertrophic scar formation. Our study provides clues for the development of HDAC5 targeting strategies for the therapy or prophylaxis of fibrotic diseases.
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