参考文献

Bone morphogenetic proteins (BMPs) initiate differentiation in human embryonic stem cells (hESCs) but the exact mechanisms have not been fully elucidated. We demonstrate here that SLUG and MSX2,transcription factors involved in epithelial-mesenchymal transitions,essential features of gastrulation in development and tumor progression,are important mediators of BMP4-induced differentiation in hESCs. Phosphorylated Smad1/5/8 colocalized with the SLUG protein at the edges of hESC colonies where differentiation takes place. The upregulation of the BMP target SLUG was direct as shown by the binding of phosphorylated Smad1/5/8 to its promoter,which interrupted the formation of adhesion proteins,resulting in migration. Knockdown of SLUG by short hairpin RNA blocked these changes,confirming an important role for SLUG in BMP-mediated mesodermal differentiation. Furthermore,BMP4-induced MSX2 expression leads to mesoderm formation and then preferential differentiation toward the cardiovascular lineage. View Publication

The fate of pluripotent stem cells is tightly controlled during early embryonic development. Both the derivation and the maintenance of embryonic stem cells (ES cells) in vitro depend on feeder cell-derived growth factors that are largely unidentified. To dissect the mechanisms governing pluripotency,we conducted a screen to identify factors that are produced by mouse embryonic fibroblast STO cells and are required to maintain the pluripotency of ES cells. One of the factors is bone morphogenetic protein 4 (BMP4). Unexpectedly,the major effect of BMP4 on the self-renewal of ES cells is accomplished by means of the inhibition of both extracellular receptor kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways,and inhibitors of ERK and p38 MAPKs mimic the effect of BMP4 on ES cells. Importantly,inhibition of the p38 MAPK pathway by SB203580 overcomes the block in deriving ES cells from blastocysts lacking a functional Alk3,the BMP type IA receptor. These results uncover a paradigm for BMP signaling in the biology of pluripotent stem cells. View Publication

The erythroid response to acute anemia relies on the rapid expansion in the spleen of a specialized population of erythroid progenitors termed stress BFU-E. This expansion requires BMP4/Madh5-dependent signaling in vivo; however,in vitro,BMP4 alone cannot recapitulate the expansion of stress BFU-E observed in vivo,which suggests that other signals are required. In this report we show that mutation of the Kit receptor results in a severe defect in the expansion of stress BFU-E,indicating a role for the Kit/SCF signaling pathway in stress erythropoiesis. In vitro analysis showed that BMP4 and SCF are necessary for the expansion of stress BFU-E,but only when spleen cells were cultured in BMP4 + SCF at low-oxygen concentrations did we recapitulate the expansion of stress BFU-E observed in vivo. Culturing spleen cells in BMP4,SCF under hypoxic conditions resulted in the preferential expansion of erythroid progenitors characterized by the expression of Kit,CD71,and TER119. This expression pattern is also seen in stress erythroid progenitors isolated from patients with sickle cell anemia and patients with beta-thalassemia. Taken together these data demonstrate that SCF and hypoxia synergize with BMP4 to promote the expansion and differentiation of stress BFU-E during the recovery from acute anemia. View Publication

Mesenchymal stromal progenitor cells (MSCs) are multipotent progenitors that can be isolated from numerous tissues. MSCs can undergo osteogenic differentiation under proper stimuli. We have recently demonstrated that bone morphogenetic protein 9 (BMP9) is one of the most osteogenic BMPs. As one of the least studied BMPs,BMP9 has been shown to regulate angiogenesis in endothelial cells. However,it is unclear whether BMP9-regulated angiogenic signaling plays any important role in the BMP9-initiated osteogenic pathway in MSCs. Here,we investigate the functional role of hypoxia-inducible factor 1α (HIF1α)-mediated angiogenic signaling in BMP9-regulated osteogenic differentiation of MSCs. We find that BMP9 induces HIF1α expression in MSCs through Smad1/5/8 signaling. Exogenous expression of HIF1α potentiates BMP9-induced osteogenic differentiation of MSCs both in vitro and in vivo. siRNA-mediated silencing of HIF1α or HIF1α inhibitor CAY10585 profoundly blunts BMP9-induced osteogenic signaling in MSCs. HIF1α expression regulated by cobalt-induced hypoxia also recapitulates the synergistic effect between HIF1α and BMP9 in osteogenic differentiation. Mechanistically,HIF1α is shown to exert its synergistic effect with BMP9 by inducing both angiogenic signaling and osteogenic signaling in MSCs. Thus,our findings should not only expand our understanding of the molecular basis behind BMP9-regulated osteoblastic lineage-specific differentiation,but also provide an opportunity to harness the BMP9-induced synergy between osteogenic and angiogenic signaling pathways in regenerative medicine. View Publication

Ovarian cancer remains the most lethal gynaecological malignancy,with tumour recurrence and chemoresistance posing significant therapeutic challenges. Emerging evidence suggests that cancer stem cells (CSCs),a rare subpopulation within tumours with self‐renewal and differentiation capacities,contribute to these hurdles. Therefore,elucidating the mechanisms that sustain CSCs is critical for improving treatment strategies. Mitophagy,a selective process for eliminating damaged mitochondria,plays a key role in maintaining cellular homeostasis,including CSC survival. Our study demonstrates that ovarian CSCs exhibit enhanced mitophagy,accompanied by elevated expression of the mitochondrial outer membrane receptors BNIP3 and BNIP3L. Knockdown of BNIP3 or BNIP3L significantly reduces mitophagy and impairs CSC self‐renewal,indicating that receptor‐mediated mitophagy is essential for CSC maintenance. Mechanistically,we identify that hyperactivated NF‐κB signalling drives the upregulation of BNIP3 and BNIP3L in ovarian CSCs. Inhibition of NF‐κB signalling,either via p65 knockdown or pharmacological inhibitors,effectively suppresses mitophagy. Furthermore,we demonstrate that elevated DNA‐PK expression contributes to the constitutive activation of NF‐κB signalling,thereby promoting mitophagy in ovarian CSCs. In summary,our findings establish that BNIP3/BNIP3L‐mediated mitophagy,driven by DNA‐PK‐dependent NF‐κB hyperactivation,is essential for CSC maintenance. Targeting the DNA‐PK/NF‐κB/BNIP3L‐BNIP3 axis to disrupt mitochondrial quality control in CSCs represents a promising therapeutic strategy to prevent ovarian cancer recurrence and metastasis. View Publication

Evidence is presented that bone marrow (BM) in addition to CD45(positive) hematopoietic stem cells contains a rare population of heterogenous CD45(negative) nonhematopoietic tissue committed stem cells (TCSC). These nonhematopoietic TCSC (i) are enriched in population of CXCR4(+) CD34(+) AC133(+) lin(-) CD45(-) and CXCR4(+) Sca-1(+) lin(-) CD45(-) in humans and mice,respectively,(ii) display several markers of pluripotent stem cells (PSC) and (iii) as we envision are deposited in BM early in development. Thus,since BM contains versatile nonhematopoietic stem cells,previous studies on plasticity trans-dedifferentiation of BM-derived hematopoietic stem cells (HSC) that did not include proper controls to exclude this possibility could lead to wrong interpretations. Therefore,in this spotlight review we present this alternative explanation of 'plasticity' of BM-derived stem cells based on the assumption that BM stem cells are heterogenous. We also discuss a potential relationship of TCSC/PSC identified by us with other BM-derived CD45(negative) nonhematopoietic stem cells that were recently identified by other investigators (eg MSC,MAPC,USSC and MIAMI cells). Finally,we discuss perspectives and pitfalls in potential application of these cells in regenerative medicine. View Publication

Although acute myeloid leukemia (AML) affects hematopoietic stem cell (HSC)-supportive microenvironment,it is largely unknown whether leukemia-modified bone marrow (BM) microenvironment can be remodeled to support normal hematopoiesis after complete remission (CR). As a key element of BM microenvironment,endothelial progenitor cells (EPCs) provide a feasible way to investigate BM microenvironment remodeling. Here,we find reduced and dysfunctional BM EPCs in AML patients,characterized by impaired angiogenesis and high ROS levels,could be partially remodeled after CR and improved by N-acetyl-L-cysteine (NAC). Importantly,HSC-supporting ability of BM EPCs is partially recovered,whereas leukemia-supporting ability is decreased in CR patients. Mechanistically,the transcriptome characteristics of leukemia-modified BM EPCs return to near-normal after CR. In a classic AML mouse and chemotherapy model,BM vasculature and normal hematopoiesis are reversed after CR. In summary,we provide further insights into how leukemia-modified BM microenvironment can be remodeled to support normal hematopoiesis after CR,which can be further improved by NAC. Subject terms: Translational research,Acute myeloid leukaemia View Publication

INTRODUCTION Bone marrow mesenchymal stem cells (BMSCs) have been extensively investigated from a perspective on cardiac regeneration therapy. The current study aimed to investigate the protective effect conferred by BMSCs in subacute myocardial injury,and to identify an appropriate BMSC reinfusion time. METHODS BMSCs were isolated from human bone marrow blood. Daunorubicin (DNR)-induced subacute myocardial models were subsequently established. The rats with DNR-induced subacute myocardial injury were injected with dexrazoxane (DZR) and/or BMSCs at varying time points,after which cardiac function was evaluated by assessing left ventricular ejection fraction (LVEF) and fraction shortening (FS). The myocardial structural changes were analyzed,after which the levels of CD3 and human leukocyte antigen DR (HLA-DR) were examined to further validate the mechanism by which BMSCs could influence subacute myocardial injury. RESULTS BMSCs combined with DZR treatment enhanced the cardiac function of rats with DNR-induced myocardial injury,as reflected by increased LVEF and FS. DNR-induced myocardial injuries were mitigated via the application of BMSCs combined with treatment of DZR,accompanied by diminished infiltration or vacuolization. Moreover,BMSCs were observed to alleviate infiltration of T lymphocyte and antigen-presenting cells,as evidenced by reduced expression of CD3 and HLA-DR. CONCLUSION Taken together,this study demonstrates that BMSCs could protect against DNR-induced myocardial injury,especially in the first three days of DNR administration. BMSCs combined with DZR exert a better therapeutic effect,but there are individual differences. View Publication

MLL-AF4 fusion is a hallmark genetic abnormality in infant B-acute lymphoblastic leukemia (B-ALL) known to arise in utero. The cellular origin of leukemic fusion genes during human development is difficult to ascertain. The bone marrow (BM) microenvironment plays an important role in the pathogenesis of several hematological malignances. BM mesenchymal stem cells (BM-MSC) from 38 children diagnosed with cytogenetically different acute leukemias were screened for leukemic fusion genes. Fusion genes were absent in BM-MSCs of childhood leukemias carrying TEL-AML1,BCR-ABL,AML1-ETO,MLL-AF9,MLL-AF10,MLL-ENL or hyperdiploidy. However,MLL-AF4 was detected and expressed in BM-MSCs from all cases of MLL-AF4(+) B-ALL. Unlike leukemic blasts,MLL-AF4(+) BM-MSCs did not display monoclonal Ig gene rearrangements. Endogenous or ectopic expression of MLL-AF4 exerted no effect on MSC culture homeostasis. These findings suggest that MSCs may be in part tumor-related,highlighting an unrecognized role of the BM milieu on the pathogenesis of MLL-AF4(+) B-ALL. MLL-AF4 itself is not sufficient for MSC transformation and the expression of MLL-AF4 in MSCs is compatible with a mesenchymal phenotype,suggesting a differential impact in the hematopoietic system and mesenchyme. The absence of monoclonal rearrangements in MLL-AF4(+) BM-MSCs precludes the possibility of cellular plasticity or de-differentiation of B-ALL blasts and suggests that MLL-AF4 might arise in a population of prehematopoietic precursors. View Publication

OBJECTIVE: Standard drugs post-myocardial infarction (MI) such as angiotensin converting enzyme (ACE) and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) increase levels of endothelial progenitor cells (EPC). However,potential underlying mechanisms have not yet been investigated. METHODS AND RESULTS: We studied the effects of ACE inhibition or statin treatment on EPC levels and on bone marrow molecular pathways involved in EPC mobilization after MI in rats. Three days post-infarction,acetylated LDL (acLDL)+/Ulex europeus-1 (UEA-1)+/VEGF receptor-2+/eNOS+ EPC levels and formation of endothelial colony forming units (CFU) were reduced to 60+/-12% (p textless 0.05) and 68+/-7% (p textless 0.05). In bone marrow,extracellular signal-regulated kinase (ERK) phosphorylation and matrix metalloproteinase (MMP)-9 activity were repressed. Endothelial nitric oxide synthase (eNOS) activity was unchanged,whereas reactive oxygen species (ROS) were increased two-fold in bone marrow. ACE or HMG-CoA reductase inhibition resulted in significant increases in EPC levels. ACE inhibition increased bone marrow ERK phosphorylation and MMP-9 activity. Statin therapy enhanced bone marrow VEGF protein levels,Akt phosphorylation,eNOS activity and normalized increased ROS levels. Augmented EPC levels in the early post-infarction phase by ACE inhibition or statin treatment were associated with improved cardiac function and increased capillary density in the peri-infarct area 7 days after MI. Moreover,increased EPC levels in response to ACE inhibition or statin treatment were sustained 10 weeks post-infarction. CONCLUSIONS: Increased ROS and impaired MMP-9 activity in bone marrow likely contribute to reduced EPC mobilization in the early post-infarction phase. ACE inhibition or statin treatment increased EPC levels with distinct drug-specific effects on bone marrow molecular alterations. View Publication