搜索结果: 'NeuroCult Proliferation'

Lysine-specific demethylase 1 (LSD1) functions as a transcriptional coregulator by modulating histone methylation. Its role in neural stem cells has not been studied. We show here for the first time that LSD1 serves as a key regulator of neural stem cell proliferation. Inhibition of LSD1 activity or knockdown of LSD1 expression led to dramatically reduced neural stem cell proliferation. LSD1 is recruited by nuclear receptor TLX,an essential neural stem cell regulator,to the promoters of TLX target genes to repress the expression of these genes,which are known regulators of cell proliferation. The importance of LSD1 function in neural stem cells was further supported by the observation that intracranial viral transduction of the LSD1 small interfering RNA (siRNA) or intraperitoneal injection of the LSD1 inhibitors pargyline and tranylcypromine led to dramatically reduced neural progenitor proliferation in the hippocampal dentate gyri of wild-type adult mouse brains. However,knockout of TLX expression abolished the inhibitory effect of pargyline and tranylcypromine on neural progenitor proliferation,suggesting that TLX is critical for the LSD1 inhibitor effect. These findings revealed a novel role for LSD1 in neural stem cell proliferation and uncovered a mechanism for neural stem cell proliferation through recruitment of LSD1 to modulate TLX activity. View Publication

Sonic hedgehog signaling pathway is important in developmental processes like dorsoventral neural tube patterning,neural stem cell proliferation and neuronal and glial cell survival. Shh is also implicated in the regulation of the adult hippocampal neurogenesis. Recently,nonpeptidyl Smoothened activators of the Shh pathway have been identified. The aim of this study was to investigate the effects of chlorobenzothiophene-containing molecule,Smo agonist (SAG),which has been shown to activate Shh signaling pathway,in neurogenesis and neuronal survival in in vitro and in vivo models. Our in vitro experiments showed that SAG induces increased expression of Gli1 mRNA,transcriptional target and mediator of Shh signal. In vitro experiments also demonstrated that SAG in low-nanomolar concentrations induces proliferation of neuronal and glial precursors without affecting the differentiation pattern of newly produced cells. In contrast to Shh,SAG did not induce neurotoxicity in neuronal cultures. The SAG and Shh treatment also promoted the survival of newly generated neural cells in the dentate gyrus after their intracerebroventricular administration to adult rats. We propose that SAG and similar compounds represent attractive molecules to be developed for treatment of disorders where stimulation of the generation and survival of new neural cells would be beneficial. View Publication

Adult mammalian cardiomyocytes are considered terminally differentiated and incapable of proliferation. Consequently,acutely injured mammalian hearts do not regenerate,they scar. Here,we show that adult mammalian cardiomyocytes can divide. One important mechanism used by mammalian cardiomyocytes to control cell cycle is p38 MAP kinase activity. p38 regulates expression of genes required for mitosis in cardiomyocytes,including cyclin A and cyclin B. p38 activity is inversely correlated with cardiac growth during development,and its overexpression blocks fetal cardiomyocyte proliferation. Activation of p38 in vivo by MKK3bE reduces BrdU incorporation in fetal cardiomyocytes by 17.6%. In contrast,cardiac-specific p38alpha knockout mice show a 92.3% increase in neonatal cardiomyocyte mitoses. Furthermore,inhibition of p38 in adult cardiomyocytes promotes cytokinesis. Finally,mitosis in adult cardiomyocytes is associated with transient dedifferentiation of the contractile apparatus. Our findings establish p38 as a key negative regulator of cardiomyocyte proliferation and indicate that adult cardiomyocytes can divide. View Publication

A chronic antigenic stimulation is believed to sustain the leukemogenic development of chronic lymphocytic leukemia (CLL) and most of lymphoproliferative malignancies developed from mature B cells. Reproducing a proliferative stimulation ex vivo is critical to decipher the mechanisms of leukemogenesis in these malignancies. However,functional studies of CLL cells remains limited since current ex vivo B cell receptor (BCR) stimulation protocols are not sufficient to induce the proliferation of these cells,pointing out the need of mandatory BCR co-factors in this process. Here,we investigated benefits of several BCR co-stimulatory molecules (IL-2,IL-4,IL-15,IL-21 and CD40 ligand) in multiple culture conditions. Our results demonstrated that BCR engagement (anti-IgM ligation) concomitant to CD40 ligand,IL-4 and IL-21 stimulation allowed CLL cells proliferation ex vivo. In addition,we established a proliferative advantage for ZAP70 positive CLL cells,associated to an increased phosphorylation of ZAP70/SYK and STAT6. Moreover,the use of a tri-dimensional matrix of methylcellulose and the addition of TLR9 agonists further increased this proliferative response. This ex vivo model of BCR stimulation with T-derived cytokines is a relevant and efficient model for functional studies of CLL as well as lymphoproliferative malignancies. View Publication

The immunosuppressive macrolide rapamycin shows marked structural similarity to FK-506,and like FK-506 inhibits the activation of cultured T and B lymphocytes at concentrations as low as 10(-10) M. However,rapamycin blocks T-lymphocyte proliferation at a much later stage than FK-506. It also inhibits human,porcine and murine T- and B-lymphocyte activation by all pathways tested,including pathways which are insensitive to FK-506,such as interleukin-2 (IL-2)-mediated proliferation of IL-2-dependent T-cell lines,activation of human peripheral blood T lymphocytes by phorbol ester and anti-CD28 and activation of murine B lymphocytes by bacterial lipopolysaccharide. Thus these two macrolides that bind competitively to the same major intracellular receptor protein inhibit T- and B-lymphocyte activation by quite distinct mechanisms. View Publication

BACKGROUND Glioblastomas (GBMs) are a heterogeneous group of primary brain tumors. These tumors are resistant to therapeutic interventions and invariably recur after surgical resection. The multifunctional protein transglutaminase 2 (TG2) has been shown to promote cell survival in a number of different tumors. There is also evidence that TG2 may be a pro-survival factor in GBMs. However,the roles that TG2 plays in facilitating GBM survival and proliferation have not yet been clearly delineated . METHODS The functions of TG2 are often cell- and context-specific. Therefore,in this study we examined the ability of TG2 to facilitate GBM proliferation using colony formation assays and 5-ethynyl-2'-deoxyuridine (EdU) incorporation in several different GBM cell lines as well as neurospheres derived from patient tumors representing the 3 major subtypes of GBM tumors (mesenchymal,proneural,and classical) and maintained in the absence of serum. TG2 knockdown or selective TG2 inhibitors were used to modulate TG2 expression and activity. RESULTS We show that TG2 plays differential roles in the proliferative process depending on the cell type. In most,but not all,GBM models TG2 plays a crucial role in the proliferative process,and some but not all TG2 inhibitors were highly effective at reducing proliferation in a large subset of the GBM models. CONCLUSION Our results show that TG2 plays an important-but notoriously context-specific-role in GBM cell biology. Nonetheless,as future studies unravel the genetic fingerprints" that make TG2 inhibitors effective this information could be exploited to develop TG2 inhibitors into personalized GBM therapies. View Publication

The aryl hydrocarbon receptor (AhR),a transcription factor known for mediating xenobiotic toxicity,is expressed in B cells,which are known targets for environmental pollutants. However,it is unclear what the physiological functions of AhR in B cells are. We show here that expression of Ahr in B cells is up-regulated upon B-cell receptor (BCR) engagement and IL-4 treatment. Addition of a natural ligand of AhR,FICZ,induces AhR translocation to the nucleus and transcription of the AhR target gene Cyp1a1,showing that the AhR pathway is functional in B cells. AhR-deficient (Ahr(-/-)) B cells proliferate less than AhR-sufficient (Ahr(+/+)) cells following in vitro BCR stimulation and in vivo adoptive transfer models confirmed that Ahr(-/-) B cells are outcompeted by Ahr(+/+) cells. Transcriptome comparison of AhR-deficient and AhR-sufficient B cells identified cyclin O (Ccno),a direct target of AhR,as a top candidate affected by AhR deficiency. View Publication

T cell homeostasis is crucial for maintaining an efficient and balanced T cell immunity. The interaction between TCR and self peptide (sp) MHC ligands is known to be the key driving force in this process,and it is believed to be functionally and mechanistically different from that initiated by the antigenic TCR stimulation. Yet,very little is known about the downstream signaling events triggered by this TCR-spMHC interaction and how they differ from those triggered by antigenic TCR stimulation. In this study,we show that T cell conditional ablation of MEKK3,a Ser/Thr kinase in the MAPK cascade,causes a significant reduction in peripheral T cell numbers in the conditional knockout mice,but does not perturb thymic T cell development and maturation. Using an adoptive mixed transfer method,we show that MEKK3-deficient T cells are severely impaired in lymphopenia-induced cell proliferation and survival. Interestingly,the Ag-induced T cell proliferation proceeds normally in the absence of MEKK3. Finally,we found that the activity of ERK1/2,but not p38 MAPK,was attenuated during the lymphopenia-driven response in MEKK3-deficient T cells. Together,these data suggest that MEKK3 may play a crucial selective role for spMHC-mediated T cell homeostasis. View Publication

In the central nervous system (CNS),neural stem cells (NSCs) differentiate into neurons,astrocytes,and oligodendrocytes--these cell lineages are considered unidirectional and irreversible under normal conditions. The introduction of a defined set of transcription factors has been shown to directly convert terminally differentiated cells into pluripotent stem cells,reinforcing the notion that preserving cellular identity is an active process. Indeed,recent studies highlight that tumor suppressor genes (TSGs) such as Ink4a/Arf and p53,control the barrier to efficient reprogramming,leaving open the question whether the same TSGs function to maintain the differentiated state. During malignancy or following brain injury,mature astrocytes have been reported to re-express neuronal genes and re-gain neurogenic potential to a certain degree,yet few studies have addressed the underlying mechanisms due to a limited number of cellular models or tools to probe this process. Here,we use a synthetic small-molecule (isoxazole) to demonstrate that highly malignant EGFRvIII-expressing Ink4a/Arf(-/-); Pten(-/-) astrocytes downregulated their astrocyte character,re-entered the cell cycle,and upregulated neuronal gene expression. As a collateral discovery,isoxazole small-molecules blocked tumor cell proliferation in vitro,a phenotype likely coupled to activation of neuronal gene expression. Similarly,histone deacetylase inhibitors induced neuronal gene expression and morphologic changes associated with the neuronal phenotype,suggesting the involvement of epigenetic-mediated gene activation. Our study assesses the contribution of specific genetic pathways underlying the de-differentiation potential of astrocytes and uncovers a novel pharmacological tool to explore astrocyte plasticity,which may bring insight to reprogramming and anti-tumor strategies. View Publication

The engineering of autologous patient T cells for adoptive cell therapies has revolutionized the treatment of several types of cancer1. However,further improvements are needed to increase response and cure rates. CRISPR-based loss-of-function screens have been limited to negative regulators of T cell functions2-4 and raise safety concerns owing to the permanent modification of the genome. Here we identify positive regulators of T cell functions through overexpression of around 12,000 barcoded human open reading frames (ORFs). The top-ranked genes increased the proliferation and activation of primary human CD4+ and CD8+ T cells and their secretion of key cytokines such as interleukin-2 and interferon-$\gamma$. In addition,we developed the single-cell genomics method OverCITE-seq for high-throughput quantification of the transcriptome and surface antigens in ORF-engineered T cells. The top-ranked ORF-lymphotoxin-$\beta$ receptor (LTBR)-is typically expressed in myeloid cells but absent in lymphocytes. When overexpressed in T cells,LTBR induced profound transcriptional and epigenomic remodelling,leading to increased T cell effector functions and resistance to exhaustion in chronic stimulation settings through constitutive activation of the canonical NF-$\kappa$B pathway. LTBR and other highly ranked genes improved the antigen-specific responses of chimeric antigen receptor T cells and ?? T cells,highlighting their potential for future cancer-agnostic therapies5. Our results provide several strategies for improving next-generation T cell therapies by the induction of synthetic cell programmes. View Publication

Adult hematopoietic stem cells (HSCs) are routinely used to reconstitute hematopoiesis after myeloablation; however,transplantation efficacy and multilineage reconstitution can be limited by inadequate HSC number,or poor homing,engraftment,or self-renewal. Here we report that mouse and human HSCs express prostaglandin E2 (PGE2) receptors,and that short-term ex vivo exposure of HSCs to PGE2 enhances their homing,survival,and proliferation,resulting in increased long-term repopulating cell (LTRC) and competitive repopulating unit (CRU) frequency. HSCs pulsed with PGE2 are more competitive,as determined by head-to-head comparison in a competitive transplantation model. Enhanced HSC frequency and competitive advantage is stable and maintained upon serial transplantation,with full multilineage reconstitution. PGE2 increases HSC CXCR4 mRNA and surface expression,enhances their migration to SDF-1 in vitro and homing to bone marrow in vivo,and stimulates HSC entry into and progression through cell cycle. In addition,PGE2 enhances HSC survival,associated with an increase in Survivin mRNA and protein expression and reduction in intracellular active caspase-3. Our results define novel mechanisms of action whereby PGE2 enhances HSC function and supports a strategy to use PGE2 to facilitate hematopoietic transplantation. View Publication