Highly expressed ribosomal protein L34 predicts poor prognosis in acute myeloid leukemia and could be a potential therapy target

Low m6A modification-mediated upregulation of PLAC8 promotes trophoblast cell invasion and migration in preeclampsia

BACKGROUND

The main symptoms of preeclampsia (PE), a specific ailment that develops during pregnancy, are proteinuria and hypertension. The pathological root of the onset and progression of PE is widely regarded as abnormal placental trophoblast cell function. This study aimed to look into the character and mechanism of Placenta-specific 8 (PLAC8) in trophoblast cell invasion and migration.

METHODS

Expressions of PLAC8 and AlkB homologue 5 (ALKBH5) were examined by western blot and quantitative real-time PCR. The m6A level of PLAC8 mRNA was detected by methylated RNA Immunoprecipitation. Using Transwell experiments, cell invasion and migration were examined. The enzyme-linked immunosorbent assay was utilized to analyze the MMP-2 and MMP-9 secretion levels. RNA pull-down and RNA immunoprecipitation were conducted to detect the binding between ALKBH5 and PLAC8.

RESULTS

In PE tissue and hypoxia-treated HTR-8/SVneo cells, levels of ALKBH5 and PLAC8 were increased, and PLAC8 m6A methylation levels were decreased. There was a positive correlation between PLAC8 and ALKBH5 expression in clinical tissues. In addition, overexpressing PLAC8 promoted HTR-8/SVneo cell migration and invasion, and so as the levels of MMP-2 and MMP-9; while interference with PLAC8 reduced the migration and invasion of hypoxia-treated HTR-8/SVneo cells, and so as the levels of MMP-2 and MMP-9. Moreover, the PLAC8 mRNA's m6A modification site was GAACU (Position 1449, Site 2). Increased levels of MMP-2 and MMP-9, as well as migration and invasion of HTR-8/SVneo cells exposed to hypoxia, were all facilitated by the m6A Site2 mutation. Furthermore, ALKBH5 could bind to PLAC8, reduce its m6A modification, and promote its expression.

CONCLUSION

High-expressed ALKBH5 inhibits the m6A level of PLAC8 mRNA and promotes PLAC8 expression, while PLAC8 overexpression can promote hypoxia-induced invasion and migration of HTR-8/Svneo cells, indicating its potential protective function in PE.

Interfering with Dusp2 alleviates high glucose-induced vascular endothelial cell dysfunction by promoting p38 MAPK pathway activation

BACKGROUND

Hyperglycemia-induced vascular endothelial cell dysfunction is a major factor contributing to diabetic lower extremity ischemia. We intend to investigate the role of Dusp2 in hyperglycemia-induced vascular endothelial cell dysfunction and related mechanisms.

METHODS

The human umbilical vein endothelial cells (HUVECs) were treated with high glucose (HG) as the cell model. Streptozotocin injection was performed to induce diabetes and femoral artery ligation was to induce hind limb ischemia in mice. The levels of Dusp2, p-p38 MAPK, E2F4, and p38 MAPK were evaluated by Western blot or quantitative real-time PCR. The laser Doppler perfusion imaging was conducted to measure blood flow recovery. The cell counting kit-8, transwell, and tube formation assay were performed to evaluate cell proliferation, migration, and angiogenesis, respectively. CD31 immunohistochemical staining was carried out to detect the capillary density of gastrocnemius. The dual-luciferase reporter gene assay and Chromatin immunoprecipitation assay were executed to explore the interaction between E2F4 and Dusp2.

RESULTS

Dusp2 was highly expressed in HG-induced HUVECs and diabetic lower extremity ischemia model mice. Interference with Dusp2 promoted cell proliferation, migration, and angiogenesis, as well as alleviated mouse diabetic hindlimb ischemia. Dusp2 knockdown up-regulated p-p38 MAPK levels. We verified the binding between E2F4 and Dusp2. Overexpressing E2F4 suppressed Dusp2 levels and promoted cell proliferation, migration, and angiogenesis, co-overexpression of Dusp2 reversed the results.

CONCLUSIONS

Overexpressing E2F4 promotes endothelial cell proliferation, migration, and angiogenesis by inhibiting Dusp2 expression and activating p38 MAPK to alleviate vascular endothelial cell dysfunction under HG stimulation.

DNMT1 mediates proliferation, migration and invasion of extravillous trophoblasts by regulating the methylation level of APLNR

INTRODUCTION

Proliferation, migration and invasion of extravillous trophoblasts (EVTs) play an important role in the progression of preeclampsia (PE). The purpose of this study was to investigate the molecular mechanism by which DNA methylase regulates the transcription level of APLNR and affects the phenotypic function of EVTs.

MATERIALS AND METHODS

PE mice model and H/R model in HTR8/Svneo cells were constructed. Clinical samples of normal pregnant women and PE patients were collected. Expression and methylation level of APLNR in vivo and in vitro were detected. ChIP-qPCR was used to detect the binding of DNA methyltransferase at the APLNR promoter. The expression of DNA methyltransferase 1 (DNMT1), NO and eNOS in vitro were detected. EVTs proliferation, migration and invasion in vitro were detected.

RESULTS

In placental tissues or HTR8/Svneo cells of the PE model group, the expression of APLNR was reduced and APLNR methylation level was up-regulated. There was no significant difference in the APLNR expression in placental tissues between normal pregnant women and PE patients. H/R conditions only promote the binding of DNMT1 at the APLNR promoter. DNMT1 interference decreased the enrichment degree of DNMT1 in APLNR promoter region and up-regulated the mRNA and protein levels of APLNR in vivo and in vitro. The activation of APLNR by Elabela (ELA) can promote eNOS transcription, thereby promoting cell proliferation and NO level, while eNOS inhibitor can reverse this effect. DNMT1 down-regulation inhibted APLNR methylation level, promoted eNOS transcription, and promoted EVTs proliferation, migration and invasion, which could be revised by the interference of APLNR.

DISCUSSION

DNMT1 promotes eNOS transcription by inhibting APLNR methylation level, and promotes EVTs proliferation, migration and invasion, thus providing a new and broad application prospect for PE treatment.

LncRNA Kcnq1ot1relieves neuropathic pain through downregulation of Myd88

BACKGROUND

Long non-coding RNAs (lncRNAs) have already been documented to become the therapeutic targets for neuropathic pain. Here, this work focused on exploring the specific mechanism underlying Kcnq1 overlapping transcript 1 (kcnq1ot1) in neuropathic pain.

METHODS

Sciatic nerve chronic constriction injury (CCI) in vivo and LPS-stimulated microglia BV2 cell injury in vitro were adopted to construct neuropathic pain models. Expressions of kcnq1ot1, MyD88, and microglia activation marker Iba-1 were measured. In this study, we carried out fluorescence in-situ Hybridization (FISH) and immunofluorescence for examining Kcnq1ot1 localization within microglial cells in mouse spinal dorsal horn. Subsequently, we evaluated binding between Kcnq1ot1 and Myd88, together with the expressions of IL-1β, IL-6, TNF-α, and Myd88 ubiquitination.

RESULTS

Kcnq1ot1 levels decreased within CCI mice and LPS-induced BV2 cells. According to the results of FISH and immunofluorescence, Kcnq1ot1 is located in microglia. Overexpression of Kcnq1ot1 suppressed Iba-1, IL-1β, IL-6 together with TNF-α expression. RNA pull-down and RIP assay confirmed that Kcnq1ot1 bound to Myd88. In addition, Kcnq1ot1 overexpression promoted the degradation, enhanced the ubiquitination, and reduced protein level of Myd88. Overexpression of Myd88 eliminated the effects of Kcnq1ot1 overexpression on Iba-1level and production of pro-inflammatory cytokines. Further in vivo results revealed that increased Kcnq1ot1 level alleviated neuropathic pain and myelinated nerve fiber injury of CCI mice.

CONCLUSION

Kcnq1ot1 downregulated Myd88 protein expression by binding to Myd88 and promoting its ubiquitination, which in turn suppressed microglia activation, pro-inflammatory cytokine production, and relieved neuropathic pain.

SUMO specific peptidase 6 regulates the crosstalk between podocytes and glomerular endothelial cells in diabetic kidney disease

There is increasing evidence that the crosstalk between podocytes and glomerular endothelial cells (GECs) exacerbates the progression of diabetic kidney disease (DKD). Here, we investigated the underlying role of SUMO specific peptidase 6 (SENP6) in this crosstalk. In the diabetic mice, SENP6 was decreased in glomerular tissues and its knockdown further exacerbated glomerular filtration barrier injury. In the mouse podocyte cell line MPC5 cells, SENP6 overexpression reversed HG-induced podocyte loss by suppressing the activation of Notch1 signaling. Notch1 intracellular domain (N1ICD) is the active form of Notch1. SENP6 upregulated the ubiquitination of N1ICD by deSUMOylating Notch1, thereby reducing N1ICD and suppressing Notch1 signaling activation in MPC5 cells. Endothelin-1 (EDN1) is a protein produced by podocytes and has been reported to promote GEC dysfunction. The supernatant from HG-treated MPC5 cells induced mitochondrial dysfunction and surface layer injury in GECs, and the supernatant from SENP6-deficient podocytes further exacerbated the above GEC dysfunction, while this trend was reversed by an EDN1 antagonist. The following mechanism study showed that SENP6 deSUMOylated KDM6A (a histone lysine demethylase) and then decreased the binding potency of KDM6A to EDN1. The latter led to the upregulation of H3K27me2 or H3K27me3 of EDN1 and suppressed its expression in podocytes. Taken together, SENP6 suppressed the HG-induced podocyte loss and ameliorated GEC dysfunction caused by crosstalk between podocytes and GECs, and the protective effect of SENP6 on DKD is attributed to its deSUMOylation activity.

Forkhead box A2-mediated lncRNA SOX2OT up-regulation alleviates oxidative stress and apoptosis of renal tubular epithelial cells by promoting SIRT1 expression in diabetic nephropathy

BACKGROUND

Renal tubular injury is the main feature of diabetic nephropathy (DN). We intend to investigate the function and related mechanisms of lncRNA SOX2 overlapping transcript (SOX2OT) in high glucose (HG)-induced oxidative stress and apoptosis of renal tubular epithelial cells (RTECs).

METHODS

To construct diabetes models, the human kidney-2 (HK-2) cells were treated with HG (30 mM), and mice were injected with streptozotocin. The levels of intracellular and mitochondrial reactive oxygen species (ROS) were assessed by dihydroethidium staining and MitoSox staining. The cell apoptosis was assessed by flow cytometry and TUNEL staining. Levels of serum creatinine, blood urea nitrogen (BUN), Urinary ACR, and oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were detected by relevant kits. In addition, fluorescence in situ hybridization staining, RNA-pull down, RNA immunoprecipitation (RIP), co-immunoprecipitation (co-IP), dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) were also executed.

RESULTS

Levels of SOX2OT and silent information regulator 1 (SIRT1) were down-regulated in HG-cultured HK-2 cells. Overexpressing SOX2OT reduced intracellular and mitochondrial ROS levels and cell apoptosis in vitro. Moreover, SOX2OT overexpression also reduced serum creatinine, BUN, urinary ACR, 8-OHdG, renal tubular injury markers KIM1 and NGAL, ROS levels, and cell apoptosis in vivo. In addition, SOX2OT promoted SIRT1 expression by suppressing its ubiquitination. Besides, interference with SIRT1 reversed the inhibitory effect of SOX2OT overexpression on HG-induced oxidative stress and apoptosis. Forkhead box A2 (Foxa2) levels were up-regulated in HG-cultured HK-2 cells. Foxa2 could bind to the SOX2OT promoter and suppress its expression. Furthermore, interfering with SOX2OT reversed the inhibitory effect of Foxa2 interference on HG-induced oxidative stress and apoptosis.

CONCLUSION

Foxa2-mediated SOX2OT up-regulation reduced oxidative stress and apoptosis of RTECs by promoting SIRT1 expression, thus alleviating the progression of DN.

GCN5 regulates ZBTB16 through acetylation, mediates osteogenic differentiation, and affects orthodontic tooth movement

In the process of orthodontic tooth movement (OTM), periodontal ligament fibroblasts (PDLFs) must undergo osteogenic differentiation. OTM increased the expression of Zinc finger and BTB domain-containing 16 (ZBTB16), which is implicated in osteogenic differentiation. Our goal was to investigate the mechanism of PDLF osteogenic differentiation mediated by ZBTB16. The OTM rat model was established, and PDLFs were isolated and exposed to mechanical force. Hematoxylin-eosin staining, Alizarin Red staining, immunofluorescence, and immunohistochemistry were carried out. The alkaline phosphatase (ALP) activity was measured. Dual-luciferase reporter gene assay and chromatin immunoprecipitation assay were conducted. In OTM models, ZBTB16 was significantly expressed. Additionally, there was an uneven distribution of PDLFs in the OTM group, as well as an increase in fibroblasts and inflammatory infiltration. ZBTB16 interference hindered PDLF osteogenic differentiation and decreased Wnt and β-catenin levels. Meanwhile, ZBTB16 activated the Wnt/β-catenin pathway. ZBTB16 also enhanced the expression of the osteogenic molecules osterix, osteocalcin (OCN), osteopontin (OPN), and bone sialo protein (BSP) at mRNA and protein levels. The interactions between Wnt1 and ZBTB16, as well as GCN5 and ZBTB16, were also verified. The adeno-associated virus-shZBTB16 injection also proved to inhibit osteogenic differentiation and reduce tooth movement distance in in vivo tests. ZBTB16 was up-regulated in OTM. Through acetylation modification of ZBTB16, GCN5 regulated the Wnt/β-catenin signaling pathway and further mediated PDLF osteogenic differentiation.

FTO inhibits oxidative stress by mediating m6A demethylation of Nrf2 to alleviate cerebral ischemia/reperfusion injury

Current therapies are of limited efficacy in cerebral ischemia/reperfusion (I/R) injury. Based on the important role of oxidative stress in cerebral I/R injury, this study aimed to explore how the N6-adenosine methylation (m6A) demethylase FTO affects oxidative stress. Middle cerebral artery occlusion/reperfusion (MCAO/R)-induced rat model and oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced SH-SY5Y cells were established as in vivo and in vitro model, respectively. The neurological score of rats was measured, and the volume of cerebral infarction was measured by TTC staining. The levels of FTO, nuclear factor-erythroid 2-related factor (Nrf2), and the activity of m6A demethylase FTO were detected. The m6A methylation level of Nrf2 mRNA was detected by MeRIP experiment. Flow cytometry and MTT assay were used to detect apoptosis and proliferation in vitro. TUNEL assay was used to detect apoptosis in brain tissues. FTO and Nrf2 expressions were decreased in the MCAO/R rat brain tissues and OGD/R SH-SY5Y cells, while the m6A methylation level of Nrf2 mRNA was significantly increased. Overexpression of FTO upregulated Nrf2 expression by decreasing the m6A methylation level of Nrf2 mRNA. m6A binding protein YT521-B homology (YTH) domain family protein 2 (YTHDF2) promoted the degradation of Nrf2 by promoting the m6A methylation level of Nrf2 mRNA. Furthermore, SH-SY5Y cell apoptosis was increased and cell viability was decreased after the addition of methyltransferases METTL 3/14, thus blocking FTO to protect SH-SY5Y cells from oxidative stress injury. In vivo, overexpression of FTO decreased the area of cerebral ischemia infarction and the extent of cell apoptosis. In conclusion, FTO increases Nrf2 expression by mediating m6A demethylation of Nrf2 mRNA, thereby inhibiting oxidative stress response and ultimately alleviating cerebral I/R injury.

AhR regulates VEGF expression by promoting STAT1 transcriptional activity, thereby affecting endothelial angiogenesis in acute limb ischemia

BACKGROUND

Angiogenesis has great potential in the treatment of acute limb ischemia (ALI). Here, we aimed to investigate the effect and mechanism of Aryl hydrocarbon receptor (AhR) on angiogenesis in ALI.

METHODS

The ALI mouse model was constructed by femoral artery ligation, and the cell ischemia injury was induced by Hypoxia/serum deprivation. The laser doppler perfusion imaging was executed to detect the limb blood flow velocity. The tube formation assay was performed to evaluate angiogenesis. The cell viability was measured by 3-(45)-dimethylthiahiazo(-z-y1)-35-di-phenytetrazoliumromide. The cell migration was detected by wound healing assay. Hematoxylin-eosin, immunohistochemistry, immunofluorescence, dual-luciferase reporter gene assay, and Chromatin immunoprecipitation assay were conducted.

RESULTS

In ALI models, AhR expression was increased and translocated from cytoplasm to nucleus. Besides, necrosis and inflammatory infiltration were also increased in gastrocnemius tissues of model mice. In addition, AhR loss (LV-sh-AhR) promoted cell viability, angiogenesis, and migration, and also elevated the levels of vascular endothelial growth factor (VEGF), Tie2, and Ang2 in HUVEC models with Hypoxia/serum deprivation injury. Meanwhile, the interaction between AhR and signal transducer and activator of transcription 1 (STAT1), as well as STAT1 and VEGF, has also been confirmed. Co-transfection of LV-sh-AhR and LV-STAT1 suppressed cell viability, angiogenesis, and migration of injured HUVECs. Furthermore, injection of AAV2/9-shAhR in vivo also promoted angiogenesis, which was consistent with the in vitro experimental results.

CONCLUSIONS

In ALI models, activated AhR was translocated to the nucleus and down-regulated VEGF expression by promoting the transcriptional activity of STAT1, thereby inhibiting endothelial angiogenesis.

SRSF1 promotes ASMC proliferation in asthma by competitively binding CCND2 with miRNA-135a

BACKGROUND

Asthma is an inflammatory syndrome characterized by airway hyperresponsiveness, bronchial inflammation, and airway remodeling. Abnormal proliferation of airway smooth muscle cells (ASMCs) is the main pathological feature of asthma. This study investigated the function and mechanism of serine arginine-rich splicing factor 1 (SRSF1) in ASMC proliferation in asthma.

METHODS

SRSF1 expressions in the bronchi of ovalbumin-induced asthmatic mice and IgE-treated mouse ASMCs (mASMCs) were evaluated using quantitative real-time PCR and Western blot. The localization and expression of SRSF1 in the bronchi of asthmatic mice were assessed by immunohistochemistry. Functionally, gain- and loss-of-function assays, flow cytometry, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were conducted. Mechanistically, RNA degradation assay, RNA immunoprecipitation, RNA pull-down, and dual-luciferase reporter gene assays were carried out.

RESULTS

SRSF1 was highly expressed in the bronchi of ovalbumin-induced asthma mice and IgE-treated mASMCs and was mainly located in the nucleus. Experiments on the function of SRSF1 showed that the silencing of SRSF1 induced the cell cycle of mASMC arrest and restrained mASMC proliferation. Investigations into the mechanism of SRSF1 revealed that SRSF1 and miR-135a are competitively bound to the 3'UTR region of Cyclin D2 (CCND2). SRSF1 overexpression repressed the degradation of CCND2 mRNA, and miR-135a negatively regulated CCND2 expression. Furthermore, SRSF1 knockdown inhibited ASMC proliferation in asthma mouse models by regulating the levels of miR-135a and CCND2.

CONCLUSION

SRSF1 knockdown repressed ASMC proliferation in asthma by regulating miR-135a/CCND2 levels.

Adipose mesenchymal stem cells-derived exosomes alleviate osteoarthritis by transporting microRNA -376c-3p and targeting the WNT-beta-catenin signaling axis

Osteoarthritis (OA), one of the major diseases afflicting the elderly, is a type of degenerative joint disease related to cartilage and synovium. This study aimed to clarify the role and mechanism of adipose mesenchymal stem cell (ADSC)-derived exosomes (Exos) in OA-induced chondrocyte degradation and synovial hyperplasia, thus improving the quality of life of patients. The rat OA model, chondrocytes, synovial fibroblast models and immunofluorescence were applied to observe the in vivo and in vitro functions of human ADSC (hADSC)-derived Exos in OA and its possible regulatory signaling pathways. Bioinformatics software and luciferase reporter assay were carried out to verify the mechanism of microRNA-376c-3p (miR-376c-3p) in hADSC-derived Exos in OA in vitro. Moreover, Safranine O-Fast Green Cartilage staining, Masson staining, immunohistochemistry and immunofluorescence were conducted to verify the role of miR-376c-3p in hADSC-derived Exos in OA in vivo. hADSC-derived Exos mitigated OA-induced chondrocyte degradation and synovial fibrosis both in vivo and in vitro models by repressing the WNT-beta-catenin signaling pathway. For the mechanism exploration in vitro, miR-376c-3p was raised in hADSC-derived Exos and mediated the fibrosis of synovial fibroblasts in OA, and miR-376c-3p targeted the 3'-untranslated region of WNT3 or WNT9a. Meanwhile, the in vivo experiments also corroborated that the miR-376c-3p in hADSC-derived Exos mitigated OA-induced chondrocyte degradation and synovial fibrosis. MiR-376c-3p in hADSC-derived Exos repressed the WNT-beta-catenin pathway by targeting WNT3 or WNT9a, and then mitigating OA-induced chondrocyte degradation and synovial fibrosis, thereby providing theoretical basis for clinical implementation of treatment.

Bone marrow mesenchymal stem cell-derived extracellular vesicles facilitate endometrial injury repair by carrying the E3 ubiquitin ligase WWP1

Bone marrow mesenchymal stem cells-derived extracellular vesicles (BMSC-EVs) relieve endometrial injury. This study aimed to elucidate the BMSC-EV mechanism in alleviating endometrial injury. Endometrial injury model in vivo was induced using 95% ethanol, and endometrial epithelial cells (EECs) treated with mifepristone were applied as an endometrial injury model in vitro. After BMSCs and BMSC-EVs were isolated and identified, the BMSC-EV function was evaluated by hematoxylin-eosin and Masson staining, immunohistochemistry, quantitative real-time PCR, Cell Counting Kit-8 assay, flow cytometry, enzyme-linked immunosorbent assay, and Transwell and tubule formation assays. The BMSC-EV mechanism was assessed using Western blot, ubiquitination, and cycloheximide-chase assays. After isolation and identification, BMSC-EVs were effective in endometrial injury repair in vivo and facilitated EEC proliferation and repressed cell apoptosis in vitro; the EEC supernatants accelerated human umbilical vein endothelial cell proliferation, migration, and invasion and facilitated angiogenesis after endometrial injury in vitro. For the BMSC-EV mechanism, E3 ubiquitin ligase WWP1 in BMSC-EVs mediated the ubiquitination of peroxisome proliferator-activated receptor gamma (PPARγ), thus relieving the PPARγ inhibition on vascular endothelial growth factor expression. Furthermore, the WWP1 in BMSC-EVs alleviated endometrial injury in vitro and in vivo. BMSC-EVs facilitated endometrial injury repair by carrying WWP1.

IL-10 inhibits osteoclast differentiation and osteolysis through MEG3/IRF8 pathway

OBJECTIVE

Osteolysis caused by wear particles is the main reason for joint replacement failure. Inhibition of osteoclast differentiation relieves wear particle-induced osteolysis. Our study aimed to explore the effect of lncRNA maternally expressed gene 3 (MEG3) on osteoclast differentiation and wear particle-induced osteolysis, and to improve the potential mechanism of interleukin-10 (IL-10) inhibition on osteoclast differentiation.

METHODS

Polymethylmethacrylate (PMMA) -induced osteolysis mice model and receptor activator of nuclear factor-B ligand (RANKL) -induced osteoclast differentiation model were constructed. Tartrate-resistant acidic phosphatase (TRAP) staining, hematoxylin-eosin (HE) staining, immunohistochemical staining, bone resorption assay, dual-luciferase assay, RNA pull-down assay, RNA immunoprecipitation, and chromatin immunoprecipitation were executed.

RESULTS

MEG3 levels were increased and interferon regulatory factor 8 (IRF8) levels were decreased in PMMA-induced osteolysis mice. IL-10 inhibited RANKL-induced osteoclast differentiation, promoted MEG3 methylation, and inhibited MEG3 expression. Moreover, knockdown of MEG3 inhibited osteoclast differentiation and increased IRF8 levels. Meanwhile, MEG3 combined with signal transducer and activator of transcription 1 (STAT1), STAT1 combined with IRF8, and overexpression of MEG3 inhibited STAT1 binding to IRF8. Further studies have shown that knockdown of MEG3 inhibited osteoclast differentiation and alleviated osteolysis, but knockdown of IRF8 weakened these results.

CONCLUSION

MEG3 regulated the expression of IRF8 by binding to STAT1, thereby affecting osteoclast differentiation and wear particle-induced osteolysis. IL-10 might inhibit osteoclast differentiation by MEG3/IRF8.

lncRNA MEG3 restrained the M1 polarization of microglia in acute spinal cord injury through the HuR/A20/NF-κB axis

The M1 polarization of microglia and neuroinflammation restrict the treatment of acute spinal cord injury (ASCI), and long non‐coding ribonucleic acid (lncRNA) maternally expressed gene 3 (MEG3) expression is lessened in ASCI. However, the function and mechanism of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI are unclear. The expressions of lncRNA MEG3 in ASCI mouse spinal cord tissues and lipopolysaccharide (LPS)‐treated primary microglia and BV2 cells were quantified through a quantitative real‐time polymerase chain reaction. In‐vitro assays were conducted to explore the function of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI. RNA degradation, RNA immunoprecipitation, RNA pull‐down, cycloheximide‐chase, and ubiquitination analyses were carried out to probe into the mechanism of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI. The lncRNA MEG3 expression was lessened in the ASCI mouse spinal cord tissues and LPS‐treated primary microglia and BV2 cells, and the overexpression of lncRNA MEG3 restrained the M1 polarization of microglia and the neuroinflammation by regulating the NF‐κB signaling pathway. For the investigation of the potential mechanism of such, the overexpression of lncRNA MEG3 restrained the M1 polarization of microglia through the HuR/A20/NF‐κB axis and boosted the motor function recovery and neuroinflammation relief in the mice with SCI. The overexpression of lncRNA MEG3 restrained the M1 polarization of microglia through the HuR/A20/NF‐κB axis.

Inhibition of PRMT6 reduces neomycin-induced inner ear hair cell injury through the restraint of FoxG1 arginine methylation

OBJECTIVE

Hair cells in the inner ear have been demonstrated to be sensitive to the ototoxicity from some beneficial pharmaceutical drugs. This study aimed to explore the role of protein arginine methyltransferase 6 (PRMT6) in the process of neomycin-induced hearing loss and the underlying mechanism.

METHODS

The neomycin-induced hearing loss mouse model and hair cell injury in vitro model were established. We took advantage of the HEI-OC1 cell line to evaluate PRMT6 expression in neomycin-induced hair cells, and the effect of PRMT6 on mitochondrial function and FoxG1 arginine methylation. Apoptotic cells were assessed and apoptotic marker cleaved caspase-3 level was detected. Reactive oxygen species (ROS) level and mitochondrial membrane potential (MMP) were subsequently measured.

RESULT

The result showed that PRMT6 was significantly upregulated in neomycin-induced HEI-OC-1 cells, and PRMT6 silencing prevented MMP loss, reduced ROS production, as well as decreased cell apoptosis under neomycin treatment. Further results showed that FoxG1 was downregulated in neomycin-induced HEI-OC-1 cells, and PRMT6 promoted the FoxG1-mediated luciferase activity, while PRMT6 silencing reversed this effect. Mechanistic experiments revealed that PRMT6 silencing reduced the arginine methylation level of FoxG1 protein. In vivo, neomycin-induced upregulation of hearing thresholds and increased cell apoptosis, whereas PRMT6 inhibitor partly reversed these effects.

CONCLUSION

Our findings suggested that inhibition of PRMT6 reduced neomycin-induced inner ear hair cell injury through the restraint of FoxG1 arginine methylation.

HUWE1 Causes an Immune Imbalance in Immune Thrombocytopenic Purpura by Reducing the Number and Function of Treg Cells Through the Ubiquitination Degradation of Ets-1

Background: Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder and the decreased number and immunosuppressive dysfunction of Treg cells are key promoters of ITP. However, their mechanisms in ITP development have not been fully clarified.

Methods: HUWE1 mRNA and protein levels in CD4⁺ T cells in peripheral blood from ITP patients were assessed by quantitative real-time PCR and Western blot. HUWE1 function in ITP was estimated using flow cytometry, enzyme-linked immunosorbent assay and immunosuppression assay. Besides, the HUWE1 mechanism in reducing the number and function of Treg cells in ITP was investigated by immunoprecipitation, cycloheximide-chase assay, ubiquitin experiment and immunofluorescence assay.

Results: HUWE1 expression was elevated in CD4⁺ T cells in peripheral blood from ITP patients and HUWE1 mRNA level was negatively correlated with platelet counts and Treg cell percentage. Moreover, the interference with HUWE1 increased the number of Treg cells and enhanced its immunosuppressive function, and the HUWE1 overexpression produced the opposite results. For the exploration of mechanism, HUWE1 interacted with E26 transformation-specific-1 (Ets-1) and this binding was dependent on the negative regulation of the phosphorylation level of Ets-1 (Thr38) and HUWE1 facilitated the ubiquitin degradation of Ets-1 protein to restrain Treg cell differentiation and weaken their immunosuppressive functions. The in vivo assay confirmed that the HUWE1 inhibitor alleviated ITP in mice.

Conclusion: HUWE1 induced the immune imbalance in ITP by decreasing the number and weakening the function of Treg cells through the ubiquitination degradation of Ets-1.

M6A methylation-mediated elevation of SM22α inhibits the proliferation and migration of vascular smooth muscle cells and ameliorates intimal hyperplasia in type 2 diabetes mellitus

Abnormal proliferation of vascular smooth muscle cells (VSMCs) induced by insulin resistance facilitates intimal hyperplasia of type 2 diabetes mellitus (T2DM) and N6-methyladenosine (m⁶A) methylation modification mediates the VSMC proliferation. This study aimed to reveal the m⁶A methylation modification regulatory mechanism. In this study, m⁶A demethylase FTO was elevated in insulin-treated VSMCs and T2DM mice with intimal injury. Functionally, FTO knockdown elevated m⁶A methylation level and further restrained VSMC proliferation and migration induced by insulin. Mechanistically, FTO knockdown elevated Smooth muscle 22 alpha (SM22α) expression and m⁶A-binding protein IGF2BP2 enhanced SM22α mRNA stability by recognizing and binding to m⁶A methylation modified mRNA. In vivo studies confirmed that the elevated m⁶A modification level of SM22α mRNA mitigated intimal hyperplasia in T2DM mice. Conclusively, m⁶A methylation-mediated elevation of SM22α restrained VSMC proliferation and migration and ameliorated intimal hyperplasia in T2DM.

lncRNA TUG1 Facilitates Colorectal Cancer Stem Cell Characteristics and Chemoresistance by Enhancing GATA6 Protein Stability

Background

Chemoresistance and tumor recurrence lead to high deaths in colorectal cancer (CRC) patients. Cancer stem cells (CSCs) contribute to these pathologic properties, but the exact mechanisms are still poorly understood. This study identified that long noncoding RNA (lncRNA) TUG1 was highly expressed in CRC stem cells and investigated its mechanism.

Methods

After the CD133⁺/CD44⁺ cells with cancer stem cell (CSC) characteristics were isolated and identified by flow cytometry, lncRNA TUG1 expression was quantified by quantitative real-time PCR. The lncRNA TUG1 function was further investigated using gain- and loss-of-function assays, sphere formation, Western blot, Cell Counting Kit-8 assay, and cell apoptosis detection. Moreover, the mechanism was explored by RNA pull-down assay, RNA immunoprecipitation, and cycloheximide- (CHX-) chase assays.

Results

lncRNA TUG1 was elevated in CD133⁺/CD44⁺ cells with CSC characteristics. Functionally, lncRNA TUG1 increased the characteristics and oxaliplatin resistance of CRC stem cells. Mechanically, lncRNA TUG1 interacted with GATA6 and positively regulated its protein level and the rescue assays corroborated that lncRNA TUG1 knockdown repressed the characteristics and oxaliplatin resistance of CRC stem cells by decreasing GATA6 and functioned in CRC by targeting the GATA6-BMP signaling pathway. Furthermore, the in vivo assay verified the lncRNA TUG1 function in facilitating the characteristics and oxaliplatin resistance of CRC stem cells.

Conclusion

lncRNA TUG1 facilitated CRC stem cell characteristics and chemoresistance by enhancing GATA6 protein stability.

PTPRM methylation induced by FN1 promotes the development of glioblastoma by activating STAT3 signalling

CONTEXT

The phosphorylation of signal transducer and activator of transcription protein 3 (STAT3) is up-regulated in glioblastoma (GBM) cells and is regulated by protein tyrosine phosphatase receptor type M (PTPRM). Fibronectin-1 (FN1) is also reported to be up-regulated in GBM.

OBJECTIVE

We explored the role of FN1-induced PTPRM methylation in GBM.

MATERIALS AND METHODS

The lentivirus particles of oe-PTPRM, sh-PTPRM, oe-FN1, sh-FN1, or their negative controls (NSCs) were transfected into GBM cells with or without stattic (0.5 μM, 24 h) or 5-aza (1 μM, 0, 2, 4 h) treatments. Methylation-specific PCR was performed to detect PTPRM methylation levels.

RESULTS

PTPRM was down-regulated (0.373 ± 0.124- and 0.455 ± 0.109-fold), FN1 and p-STAT3 were up-regulated (p < 0.001) in A172 and U87 MG cells as compared to NSCs. Overexpressing PTPRM inhibited STAT3 phosphorylation. Interfering with PTPRM increased colony numbers in A172 and U-87 MG cells (2.253 ± 0.111- and 2.043 ± 0.19-fold), and stattic reduced them. Cell viability was reduced after treatment with 5-aza in A172 and U-87 MG cells (p < 0.05). P-STAT3 was down-regulated after 5-aza treatment. Overexpressing FN1 decreased PTPRM levels (p < 0.001), knockdown of FN1 decreased PTPRM methylation and inhibited STAT3 phosphorylation. Overexpressing FN1 increased cell viability (1.497 ± 0.114- and 1.460 ± 0.151-fold), and stattic or 5-aza reversed such effects (p < 0.05).

DISCUSSION AND CONCLUSIONS

The up-regulation of FN1 reduced PTPRM by increasing its methylation, resulting in an increase of STAT3 phosphorylation and promoting GBM cell proliferation. Interfering with FN1 may be a potential therapeutic target for GBM.

Circular RNA circ-ERBB2 promotes HER2-positive breast cancer progression and metastasis via sponging miR-136-5p and miR-198

Background

Circular RNAs (circRNAs) are pivotal regulators of various human cancers and circ-ERBB2 is abnormally expressed in breast cancer cells. However, the role and mechanism of circ-ERBB2 in HER2-positive breast cancer are still unknown.

Methods

The circ-ERBB2 expressions in the tumor tissues of HER2-positive breast cancer patients were tested using quantitative real-time PCR. The circ-ERBB2 function was investigated by cell counting kit 8 assay, Transwell, flow cytometry and Western blot. Mechanistically, fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and dual-luciferase reporter gene assays were conducted to confirm the interaction between circ-ERBB2 and miR-136-5p or miR-198 in HER2-positive breast cancer cells.

Results

Circ-ERBB2 was elevated in the tumor tissues of HER2-positive breast cancer patients. Functionally, the interference with circ-ERBB2 repressed HER2-positive breast cancer cell proliferation, migration, invasion and accelerated cell apoptosis. Furthermore, the mechanistic analysis corroborated that circ-ERBB2 acted as a competing endogenous RNA for miR-136-5p or miR-198 to relieve the repressive influence of miR-136-5p or miR-198 on its target transcription factor activator protein 2C (TFAP2C). Meanwhile, in vivo assays further corroborated the oncogenic function of circ-ERBB2 in HER2-positive breast cancer.

Conclusions

Circ-ERBB2 accelerated HER2-positive breast cancer progression through the circ-ERBB2/miR-136-5p/TFAP2C axis or the circ-ERBB2/miR-198/TFAP2C axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03114-8.

Decreasing lncRNA PVT1 causes Treg/Th17 imbalance via NOTCH signaling in immune thrombocytopenia

Objectives: Immune thrombocytopenia (ITP) is an autoimmune disease. T helper cell 17 (Th17) cells are increased in peripheral blood of ITP patients. NOTCH signaling is involved in Th17 cell differentiation and function. Besides, lncRNA Plasmacytoma variant translocation 1 (PVT1) was decreased in experimental autoimmune encephalomyelitis, and overexpressing PVT1 inhibited Th17 cell differentiation. Here, we aimed to investigate the effect of lncRNA PVT1 on ITP and its related mechanism.Methods: The number of Th17 cells and Treg cells was carried out using flow cytometry. PVT1 levels were detected by quantitative real-time PCR. Interleukin-17 (IL-17) levels and transforming growth factor-β (TGF-β) levels were detected by enzyme-linked immunosorbent assay. Protein levels of retinoid acid-related orphan receptor γ t (RORγt), forkhead box P3 (Foxp3), and NOTCH1 were carried out by western blot. NOTCH1 ubiquitylation was detected by ubiquitination assay.Results: PVT1 was down-regulated and Th17 cells were up-regulated in ITP patients. Overexpression of PVT1 decreased the number of Th17 cells, and also decreased the levels of IL-17, RORγt, and NOTCH1. Besides, PVT1 could bind to NOTCH1 and mediated NOTCH1 degradation by increasing its ubiquitination. Additionally, excessive expression of PVT1 could increase the levels of PVT1, reduce the amount of Th17 cells, as well as the levels of IL-17, RORγt, and NOTCH1, while co-overexpressing NOTCH1 reversed the results.Conclusion: PVT1 was down-regulated in ITP patients. Overexpressing PVT1 might reduce Th17 cell differentiation by down-regulating NOTCH1, and further alleviated the development of ITP.

The role of miR-199b-3p in regulating Nrf2 pathway by dihydromyricetin to alleviate septic acute kidney injury

The pathophysiology of septic acute kidney injury (AKI) is very complex and the fatality is high. Nrf2 is crucial for septic AKI, and dihydromyricetin (DMY) has a protective effect on LPS-induced AKI. We aimed to explore whether DMY could affect Nrf2 pathway by regulating miR-199b-3p and played a protective role in septic AKI. The mouse model was induced by cecal ligation and puncture (CLP) and the cell model was stimulated by LPS. Enzyme-linked immunosorbent assay was conducted to examine MDA, SOD, LDH, GSH, TNF-α, kidney injury molecule 1 (KIM-1), and IL-6 levels. The pathological changes were observed by hematoxylin-eosin staining. The targeted relationship between miR-199b-3p and Nrf2 was verified by a dual-luciferase reporter assay. Levels of SOD, GSH, NQO-1, Nrf2, and HO-1 were decreased, MDA, LDH, TNF-α, IL-6, and KIM-1, and miR-199b-3p were increased in the CLP group and LPS-induced HK-2 cells, while the effect was reversed after DMY treatment. There existed renal tubule cell edema and necrosis, inflammatory cell infiltration in the CLP group, the situation was partially improved by DMY. MiR-199b-3p bound to Nrf2. Nrf2 levels were increased, TNF-α, IL-6, and KIM-1 were decreased after transfected with miR-199b-3p inhibitor, these effects were reversed when co-transfected with si-Nrf2. TNF-α, IL-6, KIM-1, and miR-199b-3p levels were increased; Nrf2, NQO-1, and HO-1 levels were decreased in the LPS + DMY + mimics-miR group. MiR-199b-3p was increased in septic AKI models, DMY might alleviate septic AKI by regulating miR-199b-3p to affect the Nrf2 pathway.

Long non-coding RNA Neat1 triggers renal tubular epithelial cell apoptosis via activating BH3-only protein in membranous nephropathy

BACKGROUND AND OBJECTIVE

Membranous nephropathy (MN) is an autoimmune disease. The up-regulation of the long non-coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (Neat1) has been found in MN but the mechanism is still unclear. Here, we explored the effect and the underlying mechanism of lncRNA Neat1 on the apoptosis of renal tubular epithelial cells in MN.

METHODS

Albumin-stimulated E11 podocytes and proximal tubular epithelial cells in vitro and the cationic-bovine serum albumin-induced MN mouse model in vivo were established. The expression of Neat1 in E11 podocytes, renal tubular epithelial cells, and renal tubules and the mRNA expression of BH3-only (the Bcl-2 homology 3-only) proteins were determined by quantitative reverse transcription-polymerase chain reaction. Levels of Cleaved Caspase 3, 6, 7, and Noxa were examined by western blotting. The number of apoptotic cells was detected by flow cytometry. Cellular proliferation was determined by 5-Ethynyl-2'-deoxyuridine and Cell Counting Kit-8 assay. Interactions between BH3-only protein Noxa and Bcl-2 as well as Bcl-xL were evaluated with co-immunoprecipitation.

RESULTS

The expression of lncRNA Neat1 was unchanged in albumin-stimulated E11 podocytes, but it was up-regulated in albumin-stimulated renal tubular epithelial cells and MN renal tubule tissues and there was a time-dependent increase in vivo. In the albumin-stimulated proximal tubular epithelial cells, overexpression of Neat1 could increase apoptosis and decrease proliferation. In turn, interference with Neat1 reduced apoptosis and increased proliferation accordingly. The mRNA expression levels of BH3-only proteins (Bad, Bim, Bid, Puma, Noxa) were detected with qRT-PCR, the results indicated that after overexpression of Neat1, mRNA and protein levels of Noxa were significantly increased, and the interference with BH3-only protein Noxa alleviated apoptosis of renal tubular epithelial cells in vitro.

CONCLUSION

In our study, we proved that lncRNA Neat1 promoted the development of MN by inducing apoptosis and this effect may be exerted by inhibiting the anti-apoptotic protein activity mediated by Noxa.

circGFRA1 affects the sensitivity of triple-negative breast cancer cells to paclitaxel via the miR-361-5p/TLR4 pathway

In recent years, the role of circular RNAs (circRNAs) in tumours has attracted widespread attention. Some circRNAs have been reported to play a role in triple-negative breast cancer (TNBC). However, circRNAs have rarely been reported in terms of TNBC resistance. This study aimed to clarify that circGFRA1 affects the sensitivity of TNBC cells to paclitaxel (PTX) by the miR-361-5p/TLR4 pathway. Compared with the non-PTX-resistant TNBC cell line MDA-MB-231, the expression of circGFRA1 in the PTX-resistant TNBC cell line MDA-MB-231.PR was significantly increased. The small hairpin RNA-mediated circGFRA1 knockdown inhibited the resistance of TNBC cells to PTX. RNA pull-down assay and luciferase reporter gene assay confirmed the binding between circGFRA1 and miR-361-5p and between miR-361-5p and TLR4. It has been proven that circGFRA1 knockdown can inhibit the resistance of TNBC cells to PTX by promoting the expression of miR-361-5p, and subsequently reduce the expression of TLR4.

LncRNA NORAD engages in psoriasis by binding to miR-26a to regulate keratinocyte proliferation

BACKGROUND

Psoriasis is a chronic, inflammatory skin disease. It was reported that lncRNA Non-coding RNA-activated by DNA damage (NORAD) has potential regulatory effects on skin diseases. Our previous studies found that lncRNA NORAD was highly expressed and its potential target miR-26a was down-regulated in psoriasis model mice. Here, we aimed to investigate the role of NORAD in the development of psoriasis.

METHODS

IL-22/LPS (interleukin-22/lipopolysaccharide)-stimulated HaCaT (human immortalized keratinocytes) cell model and imiquimod-induced mouse model were established. Keratin 6 (K6), Keratin 16 (K16), Keratin 17 (K17), and Cell division cycle 6 (CDC6) levels were detected by western blot. Cell activity was detected by CCK-8, MTT, and EdU assays. Quantitative real-time PCR was performed to examine the levels of NORAD, miR-26a, CDC6, K6, K16, and K17. Haematoxylin-eosin staining was applied to observe the degree of skin thickening and hyperplasia. Fluorescence in situ hybridization detects the location of NORAD. RNA immunoprecipitation, RNA pull-down, and Luciferase test were performed to detect the interaction between NORAD and miR-26a.

RESULTS

In IL-22/LPS-stimulated HaCaT cells, NORAD, CDC6, and keratinocyte proliferation-related proteins (K6, K16, and K17) were up-regulated and miR-26a was down-regulated. Cell survival and proliferation were also increased. However, the results were reversed after interference with NORAD. Also, in vitro experiments revealed that NORAD negatively regulated miR-26a. In IL-22/LPS-stimulated HaCaT cells and skin of imiquimod-induced mice, we found that lower NORAD resulted in an increase of miR-26a and a decrease of CDC6, further decreased levels of keratinocyte proliferation-related proteins (K6, K16, and K17).

LINC00476 Suppresses the Progression of Non-Small Cell Lung Cancer by Inducing the Ubiquitination of SETDB1

Long non-coding RNAs are involved in the tumorigenesis of non-small cell lung cancer (NSCLC). Here we investigated whether LINC00476 affects the proliferation, invasion and migration of NSCLC cells via the SETDB1-activated Wnt/β-catenin pathway. The expression of LINC00476, SETDB1, Wnt1 and β-catenin were determined in NSCLC tumor tissues and the paired adjacent tissues, as well as in NSCLC cell lines and bronchial epithelioid cell lines. Cell proliferation, invasion and migration were determined using cell counting kit-8 assay and transwell assay. The relationship between LINC00476 and SETDB1 was elucidated using RNA pull-down, RNA immunoprecipitation and ubiquitination assays. LINC00476 was found to be significantly downregulated, while SETDB1, Wnt1 and β-catenin were upregulated in NSCLC tumor tissues and cell lines compared to the normal ones. Overexpression of LINC00476 promoted the proliferation, invasion and migration of NSCLC cells, and suppressed tumor growth in the mouse xenograft. Meanwhile, overexpression of LINC00476 induced the degradation of SETDB1 by promoting its ubiquitination. The simultaneous overexpression of LINC00476 and SETDB1 negated the inhibition of LINC00476 overexpression on the proliferation, invasion and migration of NSCLC cells. In conclusion, these findings indicate that LINC00476 acts as a tumor suppressor in NSCLC by downregulating SETDB1, which provides a novel target in the treatment of NSCLC.

LncRNA-MIAT promotes neural cell autophagy and apoptosis in ischemic stroke by up-regulating REDD1

BACKGROUND

Ischemic stroke (IS) accounts for 80% of stroke incidence, which has an impact on the life quality of patients. Long non-coding RNA (LncRNA), a class of non-coding transcripts greater than 200 nucleotidesin length, has been extensively studied in cerebrovascular diseases. Myocardial infarction associated transcript (MIAT) is highly expressed in nervous system. Therefore this study aims to explore the role of LncRNA MIAT in IS and to clarify its underlying mechanism, providing therapeutic value for the treatment of IS.

METHODS

The neurological function of rats was evaluated by neurological deficit score. Triphenyltetrazolium chloride (TTC) staining was used to detect infarct area in brain tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the expression of MIAT. Western blotting was used to detect the expressions of REDD1, p-mTOR, autophagy-related proteins LC3 and p62, and apoptotic-related proteins Bax, cleaved-caspase3, Bcl-2. Flow cytometry was applied to examine neuronal cell apoptosis. RNA pull-down and RIP assay was used to verify the binding of MIAT and REDD1. The level of REDD1 ubiquitination was detected by ubiquitination and Co-immunoprecipitation (Co-IP) assay.

RESULTS

The expressions of MIAT and REDD1 were increased in IS rats and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced PC12 cell injury. After interference with si-MIAT, the results of flow cytometry showed that the rate of apoptosis was reduced. Western blotting results showed that the expression of LC3II/LC3I, Bax, and cleaved-caspase3 was decreased, while the expression of p-mTOR, p62, and Bcl-2 was increased. RNA pull-down and RIP assay found the binding relationship between MIAT and REDD1, and interference with si-MIAT down-regulated the expression of REDD1. The level of REDD1 ubiquitination was increased and the expression of REDD1 was decreased after interference with si-MIAT in PC12 cells. Co-IP results showed that interference with si-MIAT enhanced the binding ability of CUL4A-DDB1 and REDD1.

CONCLUSION

Altogether, MIAT promotes autophagy and apoptosis of neural cells and aggravates IS by up-regulating the expression of REDD1.

Specific protein 1 inhibitor mithramycin A protects cardiomyocytes from myocardial infarction via interacting with PARP

Specific protein 1 (SP1) might act as a critical transcription regulator in myocardial infarction (MI), but little evidence about its function in regulating cardiac apoptosis, a major cause of MI development, has been revealed. This study tried to investigate the role of SP1 in MI and its interaction with poly-ADP-ribose polymerase (PARP)-1 by using SP1 inhibitor, mithramycin A (mithA). Primary mouse cardiomyocytes and commercial mouse cardiomyocytes were subjected to mithA treatment under hypoxia conditions, while cell viability, Nix promoter activity, and its expression were detected correspondingly. PARP overexpression and knockdown were conducted, respectively, in mithA-treated and SP1-overexpressing cells. Co-immunoprecipitation was used to verify the interaction between PARP and SP1. For in vivo experiments, mithA administration was performed after the injections of adenovirus for PARP overexpression, and then, MI introduction was carried out. Infarct size and lactate dehydrogenase level were measured to assess MI injury. SP1 inhibitor mithA attenuated hypoxia-induced decrease of cell viability and Nix transcriptional activation, which could be inhibited by PARP overexpression. Knockdown of PARP prevented SP1-induced transcription of Nix and cell viability change, and PARP showed direct interaction with SP1. Furthermore, mithA administration reduced MI injuries, while PARP overexpression could suppress the improvement. The cardioprotective role of SP1 inhibitor mithA was demonstrated here expanding the role of SP1 in MI development involving hypoxia-induced cardiac apoptosis. Moreover, PARP acted as a transcriptional coactivator in Nix transcription involving its interaction with SP1.

Hypermethylation-mediated downregulation of long non-coding RNA MEG3 inhibits osteogenic differentiation of bone marrow mesenchymal stem cells and promotes pediatric aplastic anemia

BACKGROUND

The reduced osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is the typical characteristics of pediatric aplastic anemia (AA) pathogenesis. Long non-coding RNA MEG3 is reported to promote osteogenic differentiation of BMSCs via inducing BMP4 expression.

OBJECTIVE

This study aims to investigate the mechanism of DNMT1/MEG3/BMP4 pathway in osteogenic differentiation of BMSCs in pediatric AA.

METHODS

BMSCs were isolated and purified from bone marrows of pediatric AA patients (n = 5) and non-AA patients (n = 5). The expression of DNMT1, MEG3, and BMP4 in isolated BMSCs was detected using quantitative real-time PCR and western blot analysis. Osteogenic differentiation was determined using Alizarin red staining. The methylation of MEG3 promoter and the interaction between DNMT1 and MEG3 promoter were detected using methylation-specific PCR and chromatin immunoprecipitation assay, respectively.

RESULTS

Lowly expressed MEG3 and BMP4 and highly expressed DNMT1 were observed in BMSCs of pediatric AA patients. The overexpression of MEG3 promoted osteogenic differentiation of BMSCs. Luciferase reporter assay showed that MEG3 overexpression increased transcriptional activity of BMP4. The inhibitor of methylation, 5-azacytidine, suppressed DNMT1 expression and reduced methylation of MEG3 promoter. Overexpression of DNMT1 increased the binding between DNMT1 and MEG3 promoter. The simultaneous overexpression of DNMT1 and MEG3 restored the inhibition of osteogenic differentiation caused by DNMT1 overexpression alone.

CONCLUSIONS

Our findings indicated that DNMT1 mediated the hypermethylation of MEG3 promoter in BMSCs, and DNMT1/MEG3/BMP4 pathway modulated osteogenic differentiation of BMSCs in pediatric AA.

lncRNA-CRNDE regulates BMSC chondrogenic differentiation and promotes cartilage repair in osteoarthritis through SIRT1/SOX9

Osteoarthritis (OA) is the most common chronic and degenerative joint disease. Although traditional OA medications can partially relieve pain, these medications cannot completely cure OA. Therefore, it is particularly important to find an effective treatment for OA. This study explored the function of long non-coding RNA (lncRNA)-colorectal neoplasia differentially expressed gene (CRNDE) in the chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the underlying molecular mechanism, aiming to develop a new treatment method for osteoarthritis. BMSCs were isolated from rat bone marrow using the gradient centrifugation method. And BMSC chondrogenic differentiation was induced with chondrogenic medium. The expression of lncRNA-CRNDE was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Silent information regulator factor 2-related enzyme 1 (SIRT1) and cartilage marker genes Aggrecan and collagen 2 (α1) protein expression were researched using western blot. Alcian blue staining was employed to examine the content of cartilage matrix proteoglycan glycosaminoglycan (GAG). The interaction between lncRNA-CRNDE and SIRT1 was detected by RNA pull-down and RNA immunoprecipitation (RIP) assay. Ubiquitination experiments were performed to measure the ubiquitination level of SIRT1. The combination between SMAD ubiquitination regulatory factor 2 (SMURF2) and SIRT1, as well as SRY-related high-mobility-group box 9 (SOX9) and collagen 2 (α1) promoter, was detected by Co-immunoprecipitation or ChIP. With the prolongation of induction time, the expression of lncRNA-CRNDE, SIRT1, cartilage marker genes Aggrecan and collagen 2 (α1) in BMSC osteogenic differentiation was gradually increased. Also, the content of cartilage matrix proteoglycan GAG was gradually elevated with the extension of the induction time. Further increase in the expression of SIRT1, cartilage marker genes Aggrecan and collagen 2 (α1) by overexpression of lncRNA-CRNDE also indicated elevated GAG content. RNA pull-down and RIP assay confirmed the binding between lncRNA-CRNDE and SIRT1. qRT-PCR and western blot showed that interference with lncRNA-CRNDE significantly inhibited the protein expression of SIRT1. BMSCs transfected with si-CRNDE increased ubiquitination levels of SIRT1 mediated by the E3 ligase SMURF2, leading to the reduced protein stability of SIRT1. However, overexpression of lncRNA-CRNDE increased the binding ability of SOX9 and collagen 2 (α1) promoter, which was reversed by the simultaneous transfection of CRNDE overexpression (pcDNA-CRNDE) and SIRT1 small interfering RNA (si-SIRT1). lncRNA-CRNDE regulates BMSC chondrogenic differentiation to promote cartilage repair in osteoarthritis through SIRT1/SOX9.