Bone Morphogenetic Protein And Activin Membrane-bound Inhibitor Research Articles

Epitranscriptional regulation of TGF-β pseudoreceptor BAMBI by m6A/YTHDF2 drives extrinsic radioresistance.

Activation of TGF-β signaling serves as an extrinsic resistance mechanism that limits the potential for radiotherapy. Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) antagonizes TGF-β signaling and is implicated in cancer progression. However, the molecular mechanisms of BAMBI regulation in immune cells and its impact on antitumor immunity after radiation have not been established. Here, we show that ionizing radiation (IR) specifically reduces BAMBI expression in immunosuppressive myeloid-derived suppressor cells (MDSCs) in both murine models and humans. Mechanistically, YTH N6-methyladenosine RNA-binding protein F2 (YTHDF2) directly binds and degrades Bambi transcripts in an N6-methyladenosine-dependent (m6A-dependent) manner, and this relies on NF-κB signaling. BAMBI suppresses the tumor-infiltrating capacity and suppression function of MDSCs via inhibiting TGF-β signaling. Adeno-associated viral delivery of Bambi (AAV-Bambi) to the tumor microenvironment boosts the antitumor effects of radiotherapy and radioimmunotherapy combinations. Intriguingly, combination of AAV-Bambi and IR not only improves local tumor control, but also suppresses distant metastasis, further supporting its clinical translation potential. Our findings uncover a surprising role of BAMBI in myeloid cells, unveiling a potential therapeutic strategy for overcoming extrinsic radioresistance.

BMP and activin receptor membrane bound inhibitor: BAMBI has multiple roles in gene expression and diseases (Review).

BMP and activin membrane-bound inhibitor (BAMBI) is a transmembrane glycoprotein, known as a pseudo-receptor for TGFβ, as, while its extracellular domain is similar to that of type I TGFβ receptors, its intracellular structure is shorter and lacks a serine/threonine phosphokinase signaling motif. BAMBI can regulate numerous biological phenomena, including glucose and lipid metabolism, inflammatory responses, and cell proliferation and differentiation. Furthermore, abnormal expression of BAMBI at the mRNA and protein levels contributes to various human pathologies, including obesity and cancer. In the present review, the structure of BAMBI is briefly introduced and its associated signaling pathways and physiological functions are described. Understanding of BAMBI structure and function may contribute to knowledge regarding the occurrence of diseases, including obesity and diabetes, among others. The present review provides a theoretical foundation for the development of BAMBI as a potential biomarker or therapeutic target.

Circular RNA circSP5 promotes liver metastasis of colorectal cancer via SP5-mediated BAMBI transcription.

Liver metastasis of colorectal cancer (CRC) is a major cause of cancer morbidity and mortality. Circular RNAs (circRNAs) have been widely reported to be implicated in cancer metastasis. This study aims to investigate the effect of circSP5 (has_circ_0057010) on liver metastasis of CRC. Quantitative real-time PCR (RT-qPCR) analysis was performed to detect gene expression. The level of proteins was measured by western blot. The migration and invasion of CRC cells were assessed by wound healing assay and transwell assay. In vivo assays were performed after the construction of the CRC xenograft model and CRC model with liver metastasis. Mechanism analyses were performed via RNA-binding protein immunoprecipitation (RIP), RNA pulldown, luciferase reporter, chromatin immunoprecipitation (ChIP), and DNA pulldown assays. We found that circSP5 is significantly overexpressed in CRC with liver metastasis and its depletion suppresses the progression of CRC with liver metastasis in vitro and in vivo. Moreover, circSP5 enhances the expression of Sp5 transcription factor (SP5) via competitively sponging microRNA (miR)-1249-3p and could regulate BMP and activin membrane-bound inhibitor (BAMBI) via transcriptional activation. CircSP5 promotes the migration, invasion, and epithelial-mesenchymal transition (EMT) of CRC cells via BAMBI. In sum, circSP5 promotes liver metastasis of CRC by up-regulating SP5-mediated BAMBI transcription.

CSNK1D-mediated phosphorylation of HNRNPA2B1 induces miR-25-3p/miR-93-5p maturation to promote prostate cancer cell proliferation and migration through m6A-dependent manner.

It has been reported that heterogeneous nuclear ribonucleoprotein A2/B1 (HNRNPA2B1) is highly expressed in prostate cancer (PCa) and associated with poor prognosis of patients with PCa. Nevertheless, the specific mechanism underlying HNRNPA2B1 functions in PCa remains not clear. In our study, we proved that HNRNPA2B1 promoted the progression of PCa through in vitro and in vivo experiments. Further, we found that HNRNPA2B1 induced the maturation of miR-25-3p/miR-93-5p by recognizing primary miR-25/93 (pri-miR-25/93) through N6-methyladenosine (m6A)-dependent manner. In addition, both miR-93-5p and miR-25-3p were proven as tumor promoters in PCa. Interestingly, by mass spectrometry analysis and mechanical experiments, we found that casein kinase 1 delta (CSNK1D) could mediate the phosphorylation of HNRNPA2B1 to enhance its stability. Moreover, we further proved that miR-93-5p targeted BMP and activin membrane-bound inhibitor (BAMBI) mRNA to reduce its expression, thereby activating transforming growth factor β (TGF-β) pathway. At the same time, miR-25-3p targeted forkhead box O3 (FOXO3) to inactivate FOXO pathway. These results collectively indicated that CSNK1D stabilized HNRNPA2B1 facilitates the processing of miR-25-3p/miR-93-5p to regulate TGF-β and FOXO pathways, resulting in PCa progression. Our findings supported that HNRNPA2B1 might be a promising target for PCa treatment.

Effects of BAMBI deficiency in the development of Systemic Lupus Erythematosus

Abstract Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies and immune complexes deposition in various organs. Follicular CD4+ T cells play a crucial role in this autoimmune syndrome by activating autoreactive germinal center B cells. The transforming growth factor β (TGBβ) inhibitor BAMBI (Bone Morphogenetic Protein and Activin Membrane-Bound Inhibitor) is known to control the differentiation of CD4+ T lymphocytes into either tolerogenic Tregs or pathogenic Th17 cells. BAMBI absence in mutant mice or its pharmacological inhibition with the B101.37 monoclonal antibody promotes an increase in Treg differentiation and activity and at the same time, a reduction in Th17 cell differentiation, resulting in the inhibition of autoimmune disease development. Based on these findings, in the present study we have analysed the effects of BAMBI deficiency in the development of SLE. We have employed the chronic graft-versus-host disease lupus model induced after the transference of 40–60 × 106 lymphocytes from B6 or B6-BAMBI-KO mice into either Bm12 or Bm12-BAMBI-KO recipients. As reported previously, Bm12 mice receiving lymphocytes from B6 mice produce high levels of circulating IgG anti-DNA and anti-nucleosomal autoantibodies and exhibit linear glomerular IgG deposits in their kidneys. In contrast, both Bm12 mice injected with allogeneic B6-BAMBI-KO lymphocytes and Bm12-BAMBI-KO recipients receiving lymphocytes from B6 donors do not produce significant levels of circulating autoantibodies and do not reveal immune complexes deposits. Taken together, these results indicate that the absence of BAMBI in either donor or recipient lymphocytes protects mice against the development of SLE.

Hypoxia-responsive PPARGC1A/BAMBI/ACSL5 axis promotes progression and resistance to lenvatinib in hepatocellular carcinoma.

Emerging evidence has indicated that peroxisome proliferator-activated receptor-gamma coactivator-1α (PPARGC1A) is involved in hepatocellular carcinoma (HCC). However, its detailed function and up- and downstream mechanisms are incompletely understood. In this study, we confirmed that PPAGC1A is lowly expressed in HCC and is associated with poor prognosis using large-scale public datasets and in-house cohorts. PPAGC1A was found to impair the progression and sensitivity of HCC to lenvatinib. Mechanistically, PPAGC1A repressed bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) by inhibiting WNT/β-catenin signaling. BAMBI mediated the function of PPARGC1A and regulated ACSL5 through TGF-β/SMAD signaling. PPARGC1A/BAMBI regulated ROS production and ferroptosis-related cell death by controlling ACSL5. PPARGC1A/BAMBI/ACSL5 axis was hypoxia-responsive. METTL3 and WTAP silenced PPARGC1A in an m6A-YTHDF2-dependent way under normoxia and hypoxia, respectively. Metformin restored PPARGC1A expression by reducing its m6A modification via inhibiting METTL3. In animal models and patient-derived organoids, consistent functional data of PPARGC1A/BAMBI/ACSL5 were observed. Conclusions: These findings provide new insights into the role of the aberrant PPARGC1A/BAMBI/ACSL5 axis in HCC. And the mechanism of PPARGC1A dysregulation was explained by m6A modification. Metformin may benefit HCC patients with PPARGC1A dysregulation.

The study on role of endothelial cell autophagy in rats with sepsis-induced acute kidney injury

Sepsis often causes acute kidney injury (AKI). Autophagy of renal tubular epithelial cells is considered a cytoprotective mechanism in septic AKI; however, the role of autophagy of renal endothelial cells is uninvestigated. The current study examined whether autophagy was induced by sepsis in renal endothelial cells and whether induction of autophagy in these cells attenuated the degree of AKI. Cecal ligation and puncture (CLP) was used as a model of sepsis in rats. Four experimental groups included: sham, CLP alone, CLP + rapamycin (RAPA), and CLP + dimethyl sulfoxide (DMSO), where RAPA was used as an activator of autophagy. CLP increased renal LC3-II protein levels with an additional transient increase by RAPA at 18 h. In addition, CLP induced autophagosome formation in renal endothelial cells had an additional increase induced by RAPA. Interestingly, the levels of bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI), an endothelial cell-specific protein in the kidney, were also increased by CLP, albeit it was transiently downregulated by RAPA at 18 h. Serum thrombomodulin increased and renal vascular endothelial (VE)-cadherin decreased following CLP, and these changes were attenuated by RAPA. The renal cortex exhibited and inflammatory tissue damage after CLP, and RAPA alleviated these histopathological injuries. The current findings indicate that autophagy was induced by sepsis in renal endothelial cells, and upregulation of autophagy in these cells alleviated endothelial injury and AKI. In addition, BAMBI was induced by sepsis in the kidney, which may play a role in regulating endothelial stability in septic AKI.

Effects of BAMBI on luteinized follicular granulosa cell proliferation and steroid hormone production in sheep.

Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) regulates mammalian ovarian follicle growth and maturation; however, its effect on luteinized granulosa cells (LGCs) in sheep ovarian follicles remains unknown. Here we explored the regulatory role of LGC functions and steroid hormone synthesis by BAMBI. Multiple sequence alignment revealed that the sheep BAMBI gene sequence was relatively conserved. Sheep LGCs were strongly positive for BAMBI. LGC proliferation increased when BAMBI was silenced and decreased when BAMBI was overexpressed. After BAMBI overexpression, the expression of CASP3, CASP8, CASP9, and BAX significantly increased, whereas that of BCL2 and the ratio of BCL2/BAX expression decreased. The opposite was observed after BAMBI silencing. CDKN1A, CCND1, and CCND2 were downregulated with BAMBI overexpression and upregulated with BAMBI silencing. Expression of steroid hormone-related genes (CYP11A1, STAR, and 3BHSD), except CYP19A1, significantly increased after BAMBI overexpression. Moreover, estrogen and progesterone secretion increased after BAMBI overexpression and decreased after BAMBI interference. The effect of the exogenous addition of bone morphogenetic protein 2 (BMP2) on GCs was similar to that of BAMBI overexpression. In conclusion, BAMBI can regulate the proliferation and steroid hormone synthesis of sheep LGCs, and BMP2 can affect LGCs as an activator of BAMBI. These findings provide a basis for further research on the physiological role of BAMBI.

Expression and Function of BMP and Activin Membrane-Bound Inhibitor (BAMBI) in Chronic Liver Diseases and Hepatocellular Carcinoma.

BAMBI (bone morphogenetic protein and activin membrane-bound inhibitor) is a transmembrane pseudoreceptor structurally related to transforming growth factor (TGF)-β type 1 receptors (TGF-β1Rs). BAMBI lacks a kinase domain and functions as a TGF-β1R antagonist. Essential processes such as cell differentiation and proliferation are regulated by TGF-β1R signaling. TGF-β is the best-studied ligand of TGF-βRs and has an eminent role in inflammation and fibrogenesis. Liver fibrosis is the end stage of almost all chronic liver diseases, such as non-alcoholic fatty liver disease, and at the moment, there is no effective anti-fibrotic therapy available. Hepatic BAMBI is downregulated in rodent models of liver injury and in the fibrotic liver of patients, suggesting that low BAMBI has a role in liver fibrosis. Experimental evidence convincingly demonstrated that BAMBI overexpression is able to protect against liver fibrosis. Chronic liver diseases have a high risk of hepatocellular carcinoma (HCC), and BAMBI was shown to exert tumor-promoting as well as tumor-protective functions. This review article aims to summarize relevant studies on hepatic BAMBI expression and its role in chronic liver diseases and HCC.

BMP and activin membrane-bound inhibitor regulate connective tissue growth factor controlling mesothelioma cell proliferation

BackgroundMalignant mesothelioma (MM) is an aggressive mesothelial cell cancer type linked mainly to asbestos inhalation. MM characterizes by rapid progression and resistance to standard therapeutic modalities such as surgery, chemotherapy, and radiotherapy. Our previous studies have suggested that tumor cell-derived connective tissue growth factor (CTGF) regulates the proliferation of MM cells as well as the tumor growth in mouse xenograft models.MethodsIn this study, we knock downed the bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) and CTGF in MM cells and investigated the relationship between both and their impact on the cell cycle and cell proliferation.ResultsThe knockdown of CTGF or BAMBI reduced MM cell proliferation. In contrast to CTGF knockdown which decreased BAMBI, knockdown of BAMBI increased CTGF levels. Knockdown of either BAMBI or CTGF reduced expression of the cell cycle regulators; cyclin D3, cyclin-dependent kinase (CDK)2, and CDK4. Further, in silico analysis revealed that higher BAMBI expression was associated with shorter overall survival rates among MM patients.ConclusionsOur findings suggest that BAMBI is regulated by CTGF promoting mesothelioma growth by driving cell cycle progression. Therefore, the crosstalk between BAMBI and CTGF may be an effective therapeutic target for MM treatment.

MiR-125a-3p aggravates ox-LDL-induced HUVEC injury through BAMBI.

Atherosclerosis (AS) is a chronic inflammatory disease characterized by the formation of atherosclerotic plaque in the intima of arteries. Among the known regulators of atherosclerosis, microRNAs (miRNAs) have been reported to play critical roles in lipoprotein homeostasis and plaque formation. But the roles of microRNA-125a-3p (miR-125a-3p) in the pathogenesis of AS remain unknown. Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to construct the vascular injury model of AS pathogenesis in vitro. miR-125a-3p and BMP and activin membrane-bound inhibitor (BAMBI) expression levels in HUVECs were then measured by quantitative real-time polymerase chain reaction and western blot. The viability and apoptosis of HUVECs were analyzed by Cell Counting Kit-8 assay, TUNEL assay, and flow cytometry, respectively. The relationship between BAMBI 3'-untranslated region and miR-125a-3p was validated by dual luciferase reporter gene assay. miR-125a-3p expression was raised in HUVECs induced with ox-LDL. In HUVECs, miR-125a-3p enhanced the effects of ox-LDL treatment on repressing the viability and promoting the apoptosis of cells. Additionally, BAMBI was confirmed as a direct target of miR-125a-3p and BAMBI overexpression reversed the effects of miR-125a-3p on HUVECs. miR-125a-3p aggravates the dysfunction of HUVECs induced by ox-LDL via BAMBI, which implies that miR-125a-3p is involved in the pathogenesis of AS.

Circ_0093887 regulated ox-LDL induced human aortic endothelial cells viability, apoptosis, and inflammation through modulating miR-758-3p/BAMBI axis in atherosclerosis.

Compelling evidence demonstrated that circular RNAs (circRNAs) were involved in the progression of atherosclerosis (AS). However, the role of circ_0093887 in the progression of AS is unclear. The purpose of this study was to explore the role and mechanism of circ_0093887 in oxidized-low density lipoprotein (ox-LDL)-induced human aortic endothelial cells (HAECs). HAECs were stimulated by ox-LDL to simulate AS-like injury in vitro. Circ_0093887, microRNA-758-3p (miR-758-3p), and BMP And Activin Membrane-Bound Inhibitor (BAMBI) levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR). PCNA, Bax, Bcl-2, and BAMBI protein levels were detected by western blot. Cell viability and apoptosis were examined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Tube formation assay was used to assess tube formation. The levels of inflammatory factors TNF-α and IL-1β were detected by corresponding ELISA kits. The relationship between miR-758-3p and circ_0093887 or BAMBI was tested via dual-luciferase reporter analysis and RNA immunoprecipitation. Oxidative stress related indexes (ROS and MDA) were detected by corresponding kits. The expression levels of circ_0093887 and BAMBI were prominently downregulated in ox-LDL-induced HAECs compared with control, whereas the expression of miR-758-3p was upregulated. Overexpression of circ_0093887 promoted HAECs viability and tube formation, and restrained cell apoptosis in ox-LDL-induced HAECs compared with untreated HAECs. Mechanistically, circ_0093887 regulated the expression of BAMBI through miR-758-3p. Further experiments showed that upregulation of miR-758-3p reversed changes in cell function induced by circ_0093887. In addition, reduced BAMBI salvaged miR-758-3p knockdown mediated effects on cell function. Circ_0093887 demonstrated its diagnostic and therapeutic value in AS by promoting the role of the miR-758-3p/BAMBI axis in the ox-LDL-induced endothelial injury of HAECs.

METTL3-mediated m6A modification promotes processing and maturation of pri-miRNA-19a to facilitate nasopharyngeal carcinoma cell proliferation and invasion.

The interplay between N6-methyladenosine (m6A) modification and microRNAs (miRs) participates in cancer progression. This study is conducted to explore the role of miR-19a-3p in nasopharyngeal carcinoma (NPC) cell proliferation and invasion. Reverse transcription quantitative polymerase chain reaction and Western blot showed that miR-19a-3p was upregulated in NPC tissues and cells and related to poor prognosis, methyltransferase-like 3 (METTL3) was highly expressed, whereas BMP and activin membrane-bound inhibitor (BAMBI) was weakly expressed in NPC tissues and cells. miR-19a-3p downregulation inhibited cell proliferation and invasion, whereas miR-19a-3p overexpression played the opposite role. m6A quantification and m6A RNA immunoprecipitation assays showed that METTL3-mediated m6A modification promoted the processing and maturation of pri-miR-19a via DiGeorge syndrome critical region gene 8 (DGCR8). Dual-luciferase assay showed that BAMBI was a target of miR-19a-3p. The rescue experiments showed that BAMBI downregulation reversed the role of miR-19a-3p inhibition in NPC cells. A xenograft tumor model showed that METTL3 downregulation inhibited tumor growth via the miR-19a-3p/BAMBI in vivo. Overall, our findings elicited that METTL3-mediated m6A modification facilitated the processing and maturation of pri-miR-19a via DGCR8 to upregulate miR-19a-3p, and miR-19a-3p inhibited BAMBI expression to promote NPC cell proliferation and invasion, thus driving NPC progression.

CircNMD3 relieves endothelial cell injury induced by oxidatively modified low-density lipoprotein through regulating miR-498/ BMP and activin membrane-bound inhibitor (BAMBI) axis

ABSTRACT Atherosclerosis (AS) is one of the most common vascular diseases. The endothelial injury theory indicates that atherosclerotic plaque is the result of endothelial cell injury. Recent studies have revealed that circRNAs are abnormally expressed in AS cell models, which are implicated in the regulation of various cell behaviors. In this study, we showed the downregulation of circNMD3 in AS, and studied its role in the model of endothelial cell injury by proliferation and apoptosis assay, caspase 3 activity assay, and ELISA. We also identified and validated its downstream targets by luciferase reporter assay, RNA pull-down experiment, Western blot, and RT-qPCR. CircNMD3 overexpression or miR-498 knockdown could inhibit the ox-LDL (oxidatively modified low-density lipoprotein)-induced injury in HUVEC (human umbilical vein endothelial cells), while the co-transfection of miR-498 mimic or siRNA targeting BAMBI (BMP and activin membrane bound inhibitor) attenuated the protective effect of circNMD3 overexpression. Overall, our data suggest that circNMD3 regulates the miR-498/BAMBI axis in endothelial cells to protect ox-LDL-induced damages. As a molecular sponge of miR-498, circNMD3 regulates the level of miR-498, which in turn modulates BAMBI expression and suppresses ox-LDL-induced injury in HUVECs.

Inhibitory Effect of Astaxanthin on Gene Expression Changes in Helicobacter pylori-Infected Human Gastric Epithelial Cells.

Helicobacter pylori (H. pylori) infection promotes gastric carcinogenesis by increasing oxidative stress, inflammation, and dysregulation of cell survival and proliferation of gastric epithelial cells. Astaxanthin (ASTX), a bioactive carotenoid, exhibits antioxidant and anticancer effects by modulating aberrant signaling pathways that lead to dysregulation of cell death and proliferation. To elucidate the molecular mechanism of H. pylori-induced gastric carcinogenesis and to examine the inhibitory effect of ASTX on H. pylori-induced gastric epithelial cell gene expression changes, we performed comparative RNA-sequencing (RNA-Seq) analysis for H. pylori-infected gastric epithelial cells treated with or without ASTX. RNA-Seq results reveal that differentially expressed genes (DEGs) in H. pylori-infected cells were mainly associated with the Wnt/β-catenin signaling pathway, which is related to cell proliferation. ASTX significantly reversed H. pylori-induced transcriptional alterations of the key mediators involved in β-catenin signaling, notably, porcupine (gene symbol, PORCN), spermine oxidase (SMOX), bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI), SMAD family member 4 (SMAD4), transforming growth factor-β1 (TGFB1), Fos-like 1 (FOSLI), and c-myc (MYC). We suggest that ASTX may be a potential therapeutic agent that can suppress H. pylori-induced proliferation-associated gene expression changes, in part, by counter-regulating the Wnt/β-catenin signaling pathway.

Effect of Fibroblast Growth Factor 21 on the Expression of TLR4 and BAMBI Genes in Cholesterol-Treated Human Hepatic Stellate Cells

Background: Activated hepatic stellate cells (HSCs) are the primary mediators in the progression of hepatic fibrosis. The activation of toll-like receptor 4 (TLR4) signaling leads to the downregulation of the transmembrane inhibitory transforming growth factor-beta (TGF-β) pseudoreceptor BMP and activin membrane-bound inhibitor (BAMBI) on HSCs. Fibroblast growth factor 21 (FGF21) is a natural secretory protein in the body with effects, such as the reduction of fat accumulation and oxidation of lipids; however; no study has investigated FGF21 ability to prevent the progression of liver fibrosis. Objectives: This study aimed to examine the beneficial effects of FGF21 to reduce cholesterol-activated human HSCs. Methods: The human HSCs were incubated in media containing different concentrations of cholesterol, including 25, 50, 75, 100, 125, and 150 μM, for 24 h and then incubated with FGF21 for 24 h. Total ribonucleic acids were extracted and reversely transcribed into complementary deoxyribonucleic acid. A quantitative real-time polymerase chain reaction was performed in this study. Results: The results showed that the messenger ribonucleic acid (mRNA) expression of TGF-β, collagen, type I, alpha 1 (collagen1α), and TLR4 genes increased significantly in the presence of cholesterol (75 and 100 μM), compared to that of the control group (* P < 0.05, ** P < 0.01, and *** P < 0.001); nevertheless, the mRNA expression of the BAMBI gene significantly reduced, compared to that of the control group (* P < 0.05). The FGF21 significantly reduced the mRNA expression of TGF-β, collagen1α, and TLR4 genes (# P < 0.05). The mRNA expression of the BAMBI gene significantly increased with FGF21 (# P < 0.05). Conclusions: It was concluded that the treatment with FGF21 reduces the cholesterol-activated HSCs by decreasing the mRNA expression of the TLR4, TGF-β, and collagen1α genes and increasing the mRNA expression of the BAMBI gene.

MiR-20a-5p contributes to osteogenic differentiation of human dental pulp stem cells by regulating BAMBI and activating the phosphorylation of Smad5 and p38

BackgroundHuman dental pulp stem cells (hDPSCs) are the preferable choice of seed cells for craniomaxillofacial bone tissue regeneration. As a member of the miR-17-92 cluster, miR-20a-5p functions as an important regulator during bone remodeling. This study aimed to investigate the roles and mechanisms of miR-20a-5p during osteogenesis of hDPSCs.MethodsQuantitative reverse transcription-polymerase chain reaction (qRT-PCR) was conducted to determine the expression of miR-20a-5p during osteogenesis of hDPSCs. We interfered with the expression of miR-20a-5p in hDPSCs to clarify the function of miR-20a-5p on osteogenesis both in vitro and vivo. Direct bind sites between miR-20a-5p and BAMBI were confirmed by dual-luciferase reporter assay, and the underlying mechanisms were investigated with cell co-transfections.ResultsThe expression of miR-20a-5p was showed to be upregulated during osteogenesis of hDPSCs. Inhibition of miR-20a-5p could weaken the intensity of ALP/ARS staining and downregulate the expression of mRNAs and proteins of osteogenic markers, while overexpression of miR-20a-5p could enhance the intensity of ALP/ARS staining and the expression of osteogenic markers. Both micro-CT reconstruction images and histological results showed that miR-20a-5p could promote the regeneration of calvarial defects. miR-20a-5p directly targeted bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI), and the latter one was an inhibitor of hDPSC osteogenesis. Silencing BAMBI partially reversed the suppression effect of miR-20a-5p knockdown on osteogenesis. Phosphorylation of Smad5 and p38 was decreased when miR-20a-5p was silenced, whereas p-Smad5 and p-p38 were upregulated when miR-20a-5p was overexpressed or BAMBI was silenced.ConclusionsIt is demonstrated that miR-20a-5p functioned as a regulator of BAMBI to activate the phosphorylation of Smad5 and p38 during osteogenic differentiation of hDPSCs.

Overexpression of BAMBI and SMAD7 impacts prognosis of acute myeloid leukemia patients: A potential TERT non-canonical role.

Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) and mothers against decapentaplegic homolog 7 (SMAD7) are important transforming growth factor-β (TGF-β) signaling antagonists, however their roles in acute myeloid leukemia (AML) remains unclear. Telomerase reverse transcriptase (TERT) may be involved in regulating BAMBI and SMAD7 expressions; a role beyond telomeres that is not clinically validated yet. In this study, we examined the expression levels and prognostic values of BAMBI, SMAD7 and TERT and their association with AML patients' outcomes. Blood samples were collected from 74 de-novo AML patients and 16 controls. Real-time quantitative PCR (qRT-PCR) was performed to analyze BAMBI, SMAD7 and TERT expressions. BAMBI and SMAD7 expression in AML were significantly upregulated versus controls (p< 0.05). BAMBI, SMAD7 and TERT levels were significantly correlated together (p< 0.001). Kaplan-Meier analysis indicated that patients with high BAMBI, SMAD7 and TERT expression levels had markedly shorter event free survival (EFS) and overall survival (OS) time (p< 0.01). Furthermore, multivariate analysis revealed that only high BAMBI expression was an independent risk factor for OS (p= 0.001). BAMBI is a novel biomarker in predicting prognosis in AML patients. Moreover, a potential interplay is found between BAMBI, SMAD7 and TERT in AML pathogenies.

Collagen fiber regulation in human pediatric aortic valve development and disease

Congenital aortic valve stenosis (CAVS) affects up to 10% of the world population without medical therapies to treat the disease. New molecular targets are continually being sought that can halt CAVS progression. Collagen deregulation is a hallmark of CAVS yet remains mostly undefined. Here, histological studies were paired with high resolution accurate mass (HRAM) collagen-targeting proteomics to investigate collagen fiber production with collagen regulation associated with human AV development and pediatric end-stage CAVS (pCAVS). Histological studies identified collagen fiber realignment and unique regions of high-density collagen in pCAVS. Proteomic analysis reported specific collagen peptides are modified by hydroxylated prolines (HYP), a post-translational modification critical to stabilizing the collagen triple helix. Quantitative data analysis reported significant regulation of collagen HYP sites across patient categories. Non-collagen type ECM proteins identified (26 of the 44 total proteins) have direct interactions in collagen synthesis, regulation, or modification. Network analysis identified BAMBI (BMP and Activin Membrane Bound Inhibitor) as a potential upstream regulator of the collagen interactome. This is the first study to detail the collagen types and HYP modifications associated with human AV development and pCAVS. We anticipate that this study will inform new therapeutic avenues that inhibit valvular degradation in pCAVS and engineered options for valve replacement.

Adipose-specific BMP and activin membrane-bound inhibitor (BAMBI) deletion promotes adipogenesis by accelerating ROS production

With the improvement of people's living standards, the number of obese patients has also grown rapidly. It is reported that the level of oxidative stress in obese patients has significantly increased, mainly caused by the increase in reactive oxygen species (ROS) levels in adipose tissue. Studies have shown that the use of siRNA to interfere with bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) expression could promote adipocyte differentiation, and under hypoxic conditions, BAMBI could act as a regulator of HIF1α to regulate the polarity damage of epithelial cells. In view of these results, we speculated that BAMBI may regulate adipogenesis by regulating the level of ROS. In this study, we generated adipose-specific BAMBI knockout mice (BAMBI AKO) and found that compared with control mice, BAMBI AKO mice showed obesity when fed with high-fat diet, accompanied by insulin resistance, glucose intolerance, hypercholesterolemia, and increased inflammation in adipose tissue. Interestingly, adipose-specific deficiency of BAMBI could cause an increase in the expression level of Nox4, thereby promoting ROS production in cytoplasm and mitochondria and the DNA-binding activity of C/EBPβ and ultimately promoting adipogenesis. Consistently, our findings indicated that BAMBI may be a reactive oxygen regulator to affect adipogenesis, thereby controlling obesity and metabolic syndrome.