LncRNA GAS5 activates the HIF1A/VEGF pathway by binding to TAF15 to promote wound healing in diabetic foot ulcers.

A diabetic foot ulcer (DFU) is one of the most devastating complications of diabetes. It has been reported that lncRNA GAS5 plays a vital role in wound healing in DFUs. However, the specific mechanism remains unclear. In this research, we aimed to investigate the role of GAS5 in wound healing in DFUs as well as the underlying mechanism. qPCR or western blotting was performed to measure the expression levels of GAS5, HIF1A, VEGF and TAF15. CCK-8 or EdU assays, flow cytometry, wound healing assays and tube formation assays were carried out to assess the proliferation, apoptosis, wound healing and in vitro angiogenesis of HUVECs, respectively. RNA pull-down and RIP assays were performed to verify the interaction between GAS5 and TAF15. ChIP and luciferase assays were conducted to verify the binding of TAF15 to the HIF1A promoter. In the DFU mouse model, H&E and Masson staining were used to determine epidermal and dermal thickness and collagen formation. GAS5 and HIF1A were downregulated in the skin tissues of DFU patients, and GAS5 overexpression promoted cell proliferation, wound healing and tubule formation in HG-treated HUVECs. In addition, GAS5 facilitated HIF1A expression by interacting with TAF15. Rescue assays demonstrated that the suppression of HIF1A/VEGF pathway activation partially reversed the functional roles of GAS5 in HUVECs. Furthermore, GAS5 accelerated wound healing by activating the HIF1A/VEGF pathway in mice with DFUs. GAS5 activates the HIF1A/VEGF pathway by binding to TAF15, resulting in accelerated wound healing in DFUs. Our findings may provide a theoretical basis for the clinical treatment of DFUs.

Peng WX ，He PX ，Liu LJ ，Zhu T ，Zhong YQ ，Xiang L ，Peng K ，Yang JJ ，Xiang GD ... -  《-》

lncRNA ANRIL accelerates wound healing in diabetic foot ulcers via modulating HIF1A/VEGFA signaling through interacting with FUS.

Diabetic foot ulcer (DFU) is a frequently diagnosed complication of diabetes, and remains a heathcare burden worldwide. However, the pathogenesis of DFU is still largely unclear. The objective of this study is to delineate the function and underlying mechanism of lncRNA antisense non coding RNA in the INK4 locus (ANRIL) in endothelial progenitor cells (EPCs) and DFU mice. The DFU mouse model was established, and EPCs were subjected to high glucose (HG) treatment to mimic diabetes. qRT-PCR or western blot was employed to detected the expression of ANRIL, HIF1A, FUS and VEGFA. CCK-8 and Annexin V/PI staining were used to monitor cell proliferation and apoptosis. Wound healing, Transwell invasion and tube formation assays were conducted to assess cell migration, invasion and angiogenesis, respectively. The association between ANRIL and FUS was verified by RNA pull-down and RIP assays. Luciferase and ChIP assays were employed to investigate HIF1A-mediated transcriptional regulation of VEGFA and ANRIL. The histological alterations of DFU wound healing were observed by H&E and Masson staining. ANRIL was downregulated in peripheral blood samples of DFU patients, DFU mice and HG-treated EPCs. Mechanistically, ANRIL regulated HIFA mRNA stability via recruiting FUS. VEGFA and ANRIL were transcriptionally regulated by HIF1A. Functional experiments revealed that HG suppressed EPC proliferation, migration, invasion and tube formation, but promoted apoptosis via ANRIL/HIF1A axis. ANRIL accelerated DFU wound healing via modulating HIF1A expression in vivo. ANRIL accelerated wound healing in DFU via modulating HIF1A/VEGFA signaling in a FUS-dependent manner.

Wan J ，Bao Y ，Hou LJ ，Li GJ ，Du LJ ，Ma ZH ，Yang GK ，Hou Y ，Li ZX ，Yang Y ... -  《-》

Bone marrow stromal cell-derived exosomal circular RNA improves diabetic foot ulcer wound healing by activating the nuclear factor erythroid 2-related factor 2 pathway and inhibiting ferroptosis.

Diabetic foot ulcer (DFU) remains a serious chronic diabetic complication that can lead to disability. CircRNA-itchy E3 ubiquitin protein ligase (circ-ITCH) was observed to be down-regulated in diabetic retinopathy and diabetic nephropathy, and overexpression of circ-ITCH could inhibit the processes of these diseases. However, the detailed physiological and pathological functions of circ-ITCH in wound healing of DFU remain undetermined. Exosomes derived from bone marrow stromal cells (BMSCs) were isolated and identified. Cell viability and angiogenesis of human umbilical vein endothelial cells (HUVECs) were evaluated by cell counting kit-8 (CCK-8) and tube formation assays, respectively. The interplays of circ-ITCH, TATA-Box-binding protein associated factor 15 (TAF15) and nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA were analysed by RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) combined immunofluorescent staining and RNA pull-down assays. qRT-PCR, western blot or immunohistochemistry (IHC) were used to measure the expression of circ-ITCH, TAF15, Nrf2, vascular endothelial growth factor (VEGFR) and ferroptosis-related makers. The mice DFU model was established to verify the in vitro results. Circ-ITCH was down-regulated in in vitro and in vivo models of DFU. Deferoxamine (DFO), an iron chelating agent, improved the viability and angiogenic ability of high glucose (HG)-treated HUVECs. Overexpression of circ-ITCH or co-cultured with exosomal circ-ITCH from BMSCs could alleviate HG-induced ferroptosis and improve the angiogenesis ability of HUVECs. Circ-ITCH in HUVECs recruited TAF15 protein to stabilize Nrf2 mRNA, thus activating the Nrf2 signalling pathway and suppressing ferroptosis. Exosomal circ-ITCH from BMSCs also accelerated the wound healing process by inhibiting ferroptosis in the DFU mice in a time-dependent manner. Exosomal circ-ITCH from BMSCs inhibited ferroptosis and improved the angiogenesis of HUVECs through activation of the Nrf2 signalling pathway by recruiting TAF15 protein, ultimately accelerating the wound healing process in DFU.

Chen J ，Li X ，Liu H ，Zhong D ，Yin K ，Li Y ，Zhu L ，Xu C ，Li M ，Wang C ... -  《-》

Identification of signalling downstream of the transcription factor forkhead box protein M1 that protects against endoplasmic reticulum stress in a diabetic foot ulcer model.

Diabetic foot ulcer (DFU) has a significant impact on the quality of life of diabetic mellitus (DM) patients. Here, we aimed to explore the molecules with aberrant expression and their regulatory mechanisms in DFU. The expression of gene and protein was examined using quantitative polymerase chain reaction (qPCR) and western blot. Pearson's correlation analysis was used to analyse interactions among FOXM1, GAS5 and SDF4. Immunofluorescence was used to detect PDI and GRP78 expression. Flow cytometry was used to assess cell apoptosis. Tube formation assay was used to determine angiogenic capacity. Fluorescence in situ hybridization (FISH) assay was employed to determine the cellular localization of GAS5 and SDF4 in human umbilical vein endothelial cells (HUVECs). The interactions among FOXM1, GAS5 and SDF4 were validated by chromatin immunoprecipitation (ChIP), luciferase, RNA pull-down and RNA immunoprecipitation (RIP) assays. FOXM1, GAS5 and SDF4 were decreased in the skin tissues of DFU patients. High glucose (HG) stimulation induced endoplasmic reticulum (ER) stress and cell apoptosis but suppressed angiogenesis in HUVECs, which were abolished by FOXM1 overexpression. FOXM1 promoted GAS5 transcriptional activity, resulting in increased GAS5 expression, and GAS5 knockdown reversed the effects of FOXM1 overexpression in HG-treated HUVECs. Moreover, GAS5 recruited TAF15 to promote SDF4 expression in HUVECs. GAS5 overexpression inhibited ER stress, cell apoptosis and induced angiogenesis in HG-treated HUVECs which could be reversed by silencing SDF4. Our results revealed that FOXM1 suppressed ER stress, cell apoptosis and promoted angiogenesis in HG-induced HUVECs via mediating GAS5/TAF15/SDF4 axis, providing a novel therapeutic molecule mechanism for DFU.

Peng W ，Zhu T ，Xiang G ，Ding T ，Zhao J ，Xiong D ，Zhong Y ，Zhang Y ... -  《-》

Hyperbaric oxygen potentiates diabetic wound healing by promoting fibroblast cell proliferation and endothelial cell angiogenesis.

Diabetic foot ulcer (DFU), one of the diabetic complications, brings high burden to diabetic patients. Hyperbaric oxygen therapy (HBOT) has been proven to be an effective clinical method for the treatment of DFU. However, the mechanisms still to be elucidated. Diabetic foot mice model was established, and treated with hyperbaric oxygen. Haematoxylin & eosin (H&E) staining and Masson's trichrome staining were used for the analysis of wound healing. Human skin fibroblast (HSF) and human umbilical vein endothelial cell (HUVECS) were exposed to high glucose and hyperbaric oxygen for studying the mechanism of hyperbaric oxygen promoted wound healing in vitro. Wound healing assay, reactive oxygen species (ROS) assay, cell proliferation assay and tube formation assay were used for the analysis of wound healing. Quantitative-polymerase chain reaction (Q-PCR), Western blotting and enzyme-linked immunosorbent assay (ELISA) were used for the analysis of gene expression. HBOT facilitated wound healing in DFU mice model, and promoted the expression of HIF-1α, NF-κB, VEGFA, SDF-1, VEGFR2 and CXCR4. Hyperbaric oxygen promoted the proliferation, migration and ROS production, as well as the expression of SDF-1 and VEGFA in HSF. HBOT stimulated the proliferation, migration and tube formation, as well as the expression of CXCR4 and VEGFR2 in HUVECS. Hyperbaric oxygen potentiates angiogenesis and diabetic wound healing by activating HIF-1α signaling, so as to promote the expression of VEGF/SDF-1 in HSF and the expression of VEGFR/CXCR4 in HUVECS, ultimately to promote the proliferation of HSF and the angiogenesis of HUVECS.

Huang X ，Liang P ，Jiang B ，Zhang P ，Yu W ，Duan M ，Guo L ，Cui X ，Huang M ，Huang X ... -  《-》