SETD2 epidermal deficiency promotes cutaneous wound healing via activation of AKT/mTOR Signalling

Epigenetic modification: A novel insight into diabetic wound healing

Wound healing is an intricate and fine regulatory process. In diabetic patients, advanced glycation end products (AGEs), excessive reactive oxygen species (ROS), biofilm formation, persistent inflammation, and angiogenesis regression contribute to delayed wound healing. Epigenetics, the fast-moving science in the 21st century, has been up to date and associated with diabetic wound repair. In this review, we go over the functions of epigenetics in diabetic wound repair in retrospect, covering transcriptional and posttranscriptional regulation. Among these, we found that histone modification is widely involved in inflammation and angiogenesis by affecting macrophages and endothelial cells. DNA methylation is involved in factors regulation in wound repair but also affects the differentiation phenotype of cells in hyperglycemia. In addition, noncodingRNA regulation and RNA modification in diabetic wound repair were also generalized. The future prospects for epigenetic applications are discussed in the end. In conclusion, the study suggests that epigenetics is an integral regulatory mechanism in diabetic wound healing.

Bridging tissue repair and epithelial carcinogenesis: epigenetic memory and field cancerization

The epigenome coordinates spatial-temporal specific gene expression during development and in adulthood, for the maintenance of homeostasis and upon tissue repair. The upheaval of the epigenetic landscape is a key event in the onset of many pathologies including tumours, where epigenetic changes cooperate with genetic aberrations to establish the neoplastic phenotype and to drive cell plasticity during its evolution. DNA methylation, histone modifiers and readers or other chromatin components are indeed often altered in cancers, such as carcinomas that develop in epithelia. Lining the surfaces and the cavities of our body and acting as a barrier from the environment, epithelia are frequently subjected to acute or chronic tissue damages, such as mechanical injuries or inflammatory episodes. These events can activate plasticity mechanisms, with a deep impact on cells' epigenome. Despite being very effective, tissue repair mechanisms are closely associated with tumour onset. Here we review the similarities between tissue repair and carcinogenesis, with a special focus on the epigenetic mechanisms activated by cells during repair and opted by carcinoma cells in multiple epithelia. Moreover, we discuss the recent findings on inflammatory and wound memory in epithelia and describe the epigenetic modifications that characterise them. Finally, as wound memory in epithelial cells promotes carcinogenesis, we highlight how it represents an early step for the establishment of field cancerization.

Loss of SETD2 aggravates colorectal cancer progression caused by SMAD4 deletion through the RAS/ERK signalling pathway

BACKGOUND

Colorectal cancer (CRC) is a complex, multistep disease that arises from the interplay genetic mutations and epigenetic alterations. The histone H3K36 trimethyltransferase SET domain-containing 2 (SETD2), as an epigenetic signalling molecule, has a 5% mutation rate in CRC. SETD2 expression is decreased in the development of human CRC and mice treated with Azoxymethane /Dextran sodium sulfate (AOM/DSS). Loss of SETD2 promoted CRC development. SMAD Family member 4 (SMAD4) has a 14% mutation rate in CRC, and SMAD4 ablation leads to CRC. The co-mutation of SETD2 and SMAD4 predicted advanced CRC. However, little is known on the potential synergistic effect of SETD2 and SMAD4.

METHODS

CRC tissues from mice and SW620 cells were used as research subjects. Clinical databases of CRC patients were analyzed to investigate the association between SETD2 and SMAD4. SETD2 and SMAD4 double-knockout mice were established to further investigate the role of SETD2 in SMAD4-deficient CRC. The intestinal epithelial cells (IECs) were isolated for RNA sequencing and chromatin immunoprecipitation sequencing (ChIP-seq) to explore the mechanism and the key molecules resulting in CRC. Molecular and cellular experiments were conducted to analyze the role of SETD2 in SMAD4-deficient CRC. Finally, rescue experiments were performed to confirm the molecular mechanism of SETD2 in the development of SMAD4-dificient CRC.

RESULTS

The deletion of SETD2 promotes the malignant progression of SMAD4-deficient CRC. Smad4Vil-KO ; Setd2Vil-KO mice developed a more severe CRC phenotype after AOM/DSS induction, with a larger tumour size and a more vigorous epithelial proliferation rate. Further mechanistic findings revealed that the loss of SETD2 resulted in the down-regulation of DUSP7, which is involved in the inhibition of the RAS/ERK signalling pathway. Finally, the ERK1/2 inhibitor SCH772984 significantly attenuated the progression of CRC in Smad4Vil-KO ;Setd2Vil-KO mice, and overexpression of DUSP7 significantly inhibited the proliferation rates of SETD2KO ; SMAD4KO SW620 cells.

CONCLUSIONS

Our results demonstrated that SETD2 inhibits the RAS/ERK signaling pathway by facilitating the transcription of DUSP7 in SMAD4-deficient CRC, which could provide a potential therapeutic target for the treatment of advanced CRC.

SETD2 deficiency promotes renal fibrosis through the TGF-β/Smad signalling pathway in the absence of VHL

BACKGROUND

Renal fibrosis is the final development pathway and the most common pathological manifestation of chronic kidney disease. Epigenetic alteration is a significant intrinsic factor contributing to the development of renal fibrosis. SET domain-containing 2 (SETD2) is the sole histone H3K36 trimethyltransferase, catalysing H3K36 trimethylation. There is evidence that SETD2-mediated epigenetic alterations are implicated in many diseases. However, it is unclear what role SETD2 plays in the development of renal fibrosis.

METHODS

Kidney tissues from mice as well as HK2 cells were used as research subjects. Clinical databases of patients with renal fibrosis were analysed to investigate whether SETD2 expression is reduced in the occurrence of renal fibrosis. SETD2 and Von Hippel-Lindau (VHL) double-knockout mice were used to further investigate the role of SETD2 in renal fibrosis. Renal tubular epithelial cells isolated from mice were used for RNA sequencing and chromatin immunoprecipitation sequencing to search for molecular signalling pathways and key molecules leading to renal fibrosis in mice. Molecular and cell biology experiments were conducted to analyse and validate the role of SETD2 in the development of renal fibrosis. Finally, rescue experiments were performed to determine the molecular mechanism of SETD2 deficiency in the development of renal fibrosis.

RESULTS

SETD2 deficiency leads to severe renal fibrosis in VHL-deficient mice. Mechanically, SETD2 maintains the transcriptional level of Smad7, a negative feedback factor of the transforming growth factor-β (TGF-β)/Smad signalling pathway, thereby preventing the activation of the TGF-β/Smad signalling pathway. Deletion of SETD2 leads to reduced Smad7 expression, which results in activation of the TGF-β/Smad signalling pathway and ultimately renal fibrosis in the absence of VHL.

CONCLUSIONS

Our findings reveal the role of SETD2-mediated H3K36me3 of Smad7 in regulating the TGF-β/Smad signalling pathway in renal fibrogenesis and provide an innovative insight into SETD2 as a potential therapeutic target for the treatment of renal fibrosis.

Human Parathyroid Hormone Analog (3-34/29-34) promotes wound re-epithelialization through inducing keratinocyte migration and epithelial-mesenchymal transition via PTHR1-PI3K/AKT activation

BACKGROUND

Re-epithelialization is important in the process of wound healing. Various methods have been identified to expedite the process, but their clinical application remains limited. While parathyroid hormone (PTH) has shown promising results in wound healing due to its role in promoting collagen deposition and cell migration, application is limited by its potentially inhibitive effects when being continuously and locally administrated. Herein, we developed a novel PTH analog, Human parathyroid hormone (hPTH) (3-34/29-34) (henceforth MY-1), by partially replacing and repeating the amino acid sequences of hPTH (1-34), and evaluated its effect on skin wound re-epithelialization.

METHODS

CCK-8, colony formation unit assay, and Ki67 immunofluorescent staining were performed to evaluate the effect of MY-1 on HaCaT cell proliferation. Then, wound scratch assay, Transwell assay and lamellipodia staining were carried out to evaluate the effect of MY-1 on cell migration. Moreover, the epithelial-mesenchymal transition (EMT) markers were measured using qPCR and western blot analysis. For in-vivo drug delivery, gelatin methacryloyl (GelMA) hydrogel was employed to load the MY-1, with the physicochemical characteristics evaluated prior to its application in wound models. Then, MY-1's role in wound healing was determined via acute skin wound models. Finally, the mechanism that MY-1 activated was also detected on HaCaT cells and in-vivo wound models.

RESULTS

In-vitro, MY-1 accelerated the migration and EMT of HaCaT cells, while having little effect on cell proliferation. GelMA and MY-1-incorporated GelMA hydrogels showed similar physicochemical characteristics and were used in the in-vivo studies, where the results revealed that MY-1 led to a stronger re-epithelialization by inducing basal keratinocyte migration and EMT. Further studies on in-vivo wound models and in-vitro HaCaT cells revealed that MY-1 regulated cell migration and EMT through activating PI3K/AKT signaling. The parathyroid hormone type 1 receptor (PTHR1), the main receptor of PTH, was found to be the upstream of PI3K/AKT signaling, through interfering PTHR1 expression with a small interference RNA following detection of the PI3K/AKT activation.

CONCLUSION

Collectively, our study demonstrated that MY-1 accelerates skin wound re-epithelialization by inducing keratinocyte migration and EMT via PTHR1-PI3K/AKT axis activation. Video Abstract.

Extended characterization of IL-33/ST2 as a predictor for wound age determination in skin wound tissue samples of humans and mice

Interleukin (IL)-33, an important inflammatory cytokine, is highly expressed in skin wound tissue and serum of humans and mice, and plays an essential role in the process of skin wound healing (SWH) dependent on the IL-33/suppression of tumorigenicity 2 (ST2) pathway. However, whether IL-33 and ST2 themselves, as well as their interaction, can be applied for skin wound age determination in forensic practice remains incompletely characterized. Human skin samples with injured intervals of a few minutes to 24 hours (hs) and mouse skin samples with injured intervals of 1 h to 14 days (ds) were collected. Herein, the results demonstrated that IL-33 and ST2 are increased in the human skin wounds, and that in mice skin wounds, there is an increase over time, with IL-33 expression peaking at 24 hs and 10 ds, and ST2 expression peaking at 12 hs and 7 ds. Notably, the relative quantity of IL-33 and ST2 proteins < 0.35 suggested a wound age of 3 hs; their relative quantity > 1.0 suggested a wound age of 24 hs post-mouse skin wounds. In addition, immunofluorescent staining results showed that IL-33 and ST2 were consistently expressed in the cytoplasm of F4/80-positive macrophages and CD31-positive vascular endothelial cells with or without skin wounds, whereas nuclear localization of IL-33 was absent in α-SMA-positive myofibroblasts with skin wounds. Interestingly, IL-33 administration facilitated the wound area closure by increasing the proliferation of cytokeratin (K) 14 -positive keratinocytes and vimentin-positive fibroblasts. In contrast, treating with its antagonist (i.e., anti-IL-33) or receptor antagonist (e.g., anti-ST2) exacerbated the aforementioned pathological changes. Moreover, treatment with IL-33 combined with anti-IL-33 or anti-ST2 reversed the effect of IL-33 on facilitating skin wound closure, suggesting that IL-33 administration facilitated skin wound closure through the IL-33/ST2 signaling pathway. Collectively, these findings indicate that the detection of IL-33/ST2 might be a reliable biomarker for the determination of skin wound age in forensic practice.

Heparin-based sericin hydrogel-encapsulated basic fibroblast growth factor for in vitro and in vivo skin repair

The treatment of full-thickness cutaneous wounds remains a significant challenge in clinical therapeutics. Exogenous growth factor (GF) has been applied in clinics to promote wound healing. However, the retention of GF on the wound bed after its direct application to the wound surface is difficult. Moreover, growth factors (GFs) are always inactivated in the complex wound healing microenvironment due to various factors, which significantly decrease the therapeutic effect. Sericin hydrogel (S) can be used as an effective carrier for GFs owing to its low immunogenicity, good biocompatibility, and good healing-promoting ability. Here, we designed a heparin-based sericin hydrogel (HS) -encapsulated basic fibroblast growth factor (bFGF-HS) to facilitate wound healing and skin regeneration. The hydrogel exhibited a three-dimensional (3D) microporous structure, excellent biodegradability, good adhesiveness, and low cytotoxicity. In vitro release of bFGF from bFGF-HS coacervates revealed that bFGF-HS might control the release of bFGF within 25 days through heparin regulation. bFGF-HS significantly promoted vascularization and re-epithelialization and improved collagen deposition, ultimately accelerating wound healing in vivo in mice. bFGF-HS treated wounds were also found to have more hair follicles and milder inflammatory reactions. Overall, this study provides a new therapeutic approach for full-thickness skin defect wounds using bFGF-HS.

Severe Burn Injury Significantly Alters the Gene Expression and m6A Methylation Tagging of mRNAs and lncRNAs in Human Skin

N6-methyladenosine (m6A) modulates RNA metabolism and functions in cell differentiation, tissue development, and immune response. After acute burns, skin wounds are highly susceptible to infection and poor healing. However, our understanding of the effect of burn injuries on m6A methylation and their potential mechanism is still limited. Human m6A-mRNA&lncRNA Epitranscriptomic microarray was used to obtain comprehensive mRNA and lncRNA transcriptome m6A profiling and gene expression patterns after burn injuries in human skin tissue. Bioinformatic and functional analyses were conducted to find molecular functions. Microarray profiling showed that 65 mRNAs and 39 lncRNAs were significantly hypermethylated; 5492 mRNAs and 754 lncRNAs were significantly hypomethylated. Notably, 3989 hypomethylated mRNAs were down-expressed and inhibited many wound healing biological processes and pathways including in the protein catabolic process and supramolecular fiber organization pathway; 39 hypermethylated mRNAs were up-expressed and influenced the cell surface receptor signaling pathway and inflammatory response. Moreover, we validated that m6A regulators (METTL14, METTL16, ALKBH5, FMR1, and HNRNPC) were significantly downregulated after burn injury which may be responsible for the alteration of m6A modification and gene expression. In summary, we found that homeostasis in the skin was disrupted and m6A modification may be a potential mechanism affecting trauma infection and wound healing.

Porcine Acellular Dermal Matrix Promotes Migration and Suppresses Inflammation of Keratinocytes by Mediating the AKT Signaling Pathway

Porcine acellular dermal matrix (pADM) is known to accelerate wound healing. However, the underlying molecular mechanism remains unclear. This study aimed to investigate the effects of pADM on wound healing and its underlying mechanisms. HaCaT cells were treated with hydrogen peroxide (H2O2) or pADM, and the appropriate treatment concentration was determined using the cell counting kit-8 and flow cytometry. Cell migration was assessed using a Transwell assay and scratch test. Inflammation was evaluated using enzyme-linked immunosorbent assay. Western blotting was performed to measure the levels of protein kinase B (AKT) pathway-related proteins. The results showed that H2O2 inhibited cell viability and induced apoptosis in a dose-dependent manner. pADM promoted cell migration and decreased the levels of interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in H2O2-treated HaCaT cells. Moreover, pADM rescued the downregulation of phosphorylated (p)-AKT and p-mechanistic target of rapamycin (mTOR) induced by H2O2. LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, abrogated migration and anti-inflammatory response caused by pADM. In conclusion, pADM promotes cell migration and inhibits inflammation by activating the AKT pathway under oxidative stress. These findings support the use of pADM for post-traumatic therapy and reveal a novel underlying mechanism of action.

Landscape of the epigenetic regulation in wound healing

Wound healing after skin injury is a dynamic and highly coordinated process involving a well-orchestrated series of phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Epigenetic regulation refers to genome-wide molecular events, including DNA methylation, histone modification, and non-coding RNA regulation, represented by microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA). Epigenetic regulation is pervasively occurred in the genome and emerges as a new role in gene expression at the post-transcriptional level. Currently, it is well-recognized that epigenetic factors are determinants in regulating gene expression patterns, and may provide evolutionary mechanisms that influence the wound microenvironments and the entire healing course. Therefore, this review aims to comprehensively summarize the emerging roles and mechanisms of epigenetic remodeling in wound healing. Moreover, we also pose the challenges and future perspectives related to epigenetic modifications in wound healing, which would bring novel insights to accelerated wound healing.

ADSC-exo@MMP-PEG smart hydrogel promotes diabetic wound healing by optimizing cellular functions and relieving oxidative stress

Diabetic wound complications are financially costly and difficult to heal in worldwide. Whereas the therapies of diabetic wound, such as wound dressing, endocrine therapy or flap-transplantations, were not satisfied. Based on our previous study of exosome secreted by adipose-derived stem cell (ADSC-exo), we loaded ADSC-exo into the matrix metalloproteinase degradable polyethylene glycol (MMP-PEG) smart hydrogel. Physical and chemical properties of ADSC-exo@MMP-PEG smart hydrogel were tested by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), weight loss examination, etc. As the hydrogel degraded in response to MMP, ADSC-exo was released and subsequently enhanced cell function via Akt signaling. Moreover, treatment with ADSC-exo@MMP-PEG smart hydrogel significantly relieved the H₂O₂-induced oxidative stress, which was widely recognized as a major cause of diabetic wound nonhealing. Similar results were achieved in mice diabetic wound models, in which the ADSC-exo@MMP-PEG treatment group displayed a significantly accelerated wound healing. To summarize, the present smart hydrogel with enzyme-response and exosome-release was proved to be benefit for diabetic wounds healing, which provides a reliable theoretical basis for application of ADSC-exo in treatment of diabetic wounds.

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Loading ADSC-exo into PEG formed a smart hydrogel.

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The smart hydrogel delivered exosome in response to MMP-2.

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The smart hydrogel promoted diabetic wound healing by optimizing cellular functions.

SLC7A11 regulated by NRF2 modulates esophageal squamous cell carcinoma radiosensitivity by inhibiting ferroptosis

BACKGROUND

Solute carrier family 7 member 11(SLC7A11) is a component of cysteine/glutamate transporter, which plays a key role in tumor growth; however, its underlying effect on radiosensitivity in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to clarify SLC7A11's expression and correlation with nuclear expression of nuclear factor erythroid-2 (NRF2)-associated radioresistance in ESCC.

METHODS

We included 127 ESCC patients who received radical chemoradiotherapy. Immunohistochemical staining was used to detect SLC7A11 and NRF2 nuclear expression, and the relationship between clinicopathological characteristics and survival rates or therapy response were evaluated. Western blot, dual-reporter assays and Chromatin immunoprecipitation (ChIP)-sequencing were used to analyze their relationship in vitro. Their roles in radioresistance were then investigated through multiple validation steps.

RESULTS

NRF2 nuclear expression and SLC7A11 expression were overexpressed in ESCC tissues and were positively correlated with one another. NRF2 nuclear expression was significantly associated with tumor length, lymph node metastasis, and TNM stage, while SLC7A11 expression was associated with lymph node metastasis. Patients with high NRF2 nuclear expression and SLC7A11 expression had significantly shorter overall and progression-free survival, and poor treatment response. The multivariate model showed that NRF2 nuclear expression and SLC7A11 expression, sex and tumor location are independent prognostic factors. In vitro analysis confirmed that hyperactivation of NRF2 induced SLC7A11 expression by directly binding to its promoter region, promoting radioresistance, reducing radiotherapy-induced lipid peroxidation levels, PTGS2 expression, and radiotherapy-related ferroptosis morphologic features.

CONCLUSION

Our study reveals a connection between high SLC7A11 expression and NRF2 nuclear expression in patients with ESCC that was related to worse survival and poorer therapy outcomes. SLC7A11-mediated ferroptosis inhibition induced NRF2-associated radioresistance, highlighting potential of NRF2/SLC7A11/ferroptosis axis as future therapeutic targets against therapy resistance biomarker.

SETD2 epidermal deficiency promotes cutaneous wound healing via activation of AKT/mTOR Signalling

Objectives

Cutaneous wound healing is one of the major medical problems worldwide. Epigenetic modifiers have been identified as important players in skin development, homeostasis and wound repair. SET domain–containing 2 (SETD2) is the only known histone H3K36 tri‐methylase; however, its role in skin wound healing remains unclear.

Materials and Methods

To elucidate the biological role of SETD2 in wound healing, conditional gene targeting was used to generate epidermis‐specific Setd2‐deficient mice. Wound‐healing experiments were performed on the backs of mice, and injured skin tissues were collected and analysed by haematoxylin and eosin (H&E) and immunohistochemical staining. In vitro, CCK8 and scratch wound‐healing assays were performed on Setd2‐knockdown and Setd2‐overexpression human immortalized keratinocyte cell line (HaCaT). In addition, RNA‐seq and H3K36me3 ChIP‐seq analyses were performed to identify the dysregulated genes modulated by SETD2. Finally, the results were validated in functional rescue experiments using AKT and mTOR inhibitors (MK2206 and rapamycin).

Results

Epidermis‐specific Setd2‐deficient mice were successfully established, and SETD2 deficiency resulted in accelerated re‐epithelialization during cutaneous wound healing by promoting keratinocyte proliferation and migration. Furthermore, the loss of SETD2 enhanced the scratch closure and proliferation of keratinocytes in vitro. Mechanistically, the deletion of Setd2 resulted in the activation of AKT/mTOR signalling pathway, while the pharmacological inhibition of AKT and mTOR with MK2206 and rapamycin, respectively, delayed wound closure.

Conclusions

Our results showed that SETD2 loss promoted cutaneous wound healing via the activation of AKT/mTOR signalling.