搜索结果: 'NeuroCult Proliferation'

Increased levels of intestinal bile acids (BAs) are a risk factor for colorectal cancer (CRC). Here,we show that the convergence of dietary factors (high-fat diet) and dysregulated WNT signaling (APC mutation) alters BA profiles to drive malignant transformations in Lgr5-expressing (Lgr5+) cancer stem cells and promote an adenoma-to-adenocarcinoma progression. Mechanistically,we show that BAs that antagonize intestinal farnesoid X receptor (FXR) function,including tauro-$\beta$-muricholic acid (T-$\beta$MCA) and deoxycholic acid (DCA),induce proliferation and DNA damage in Lgr5+ cells. Conversely,selective activation of intestinal FXR can restrict abnormal Lgr5+ cell growth and curtail CRC progression. This unexpected role for FXR in coordinating intestinal self-renewal with BA levels implicates FXR as a potential therapeutic target for CRC. View Publication

Aim Reactive oxygen species (ROS) produced by enzymes of the NADPH oxidase family serve as second messengers for cellular signaling. Processes such as differentiation and proliferation are regulated by NADPH oxidases. In the intestine,due to the exceedingly fast and constant renewal of the epithelium both processes have to be highly controlled and balanced. Nox1 is the major NADPH oxidase expressed in the gut,and its function is regulated by cytosolic subunits such as NoxO1. We hypothesize that the NoxO1-controlled activity of Nox1 contributes to a proper epithelial homeostasis and renewal in the gut. Results NoxO1 is highly expressed in the colon. Knockout of NoxO1 reduces the production of superoxide in colon crypts and is not subsidized by an elevated expression of its homolog p47phox. Knockout of NoxO1 increases the proliferative capacity and prevents apoptosis of colon epithelial cells. In mouse models of dextran sulfate sodium (DSS)-induced colitis and azoxymethane/DSS induced colon cancer,NoxO1 has a protective role and may influence the population of natural killer cells. Conclusion NoxO1 affects colon epithelium homeostasis and prevents inflammation. View Publication

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

Background & AimsType 2 innate lymphoid cells (ILC2s) and interleukin-13 (IL-13) promote the onset of spasmolytic polypeptide-expressing metaplasia (SPEM) cells. However,little is known about molecular effects of IL-13 in SPEM cells. We now sought to establish a reliable organoid model,Meta1 gastroids,to model SPEM cells in vitro. We evaluated cellular and molecular effects of ILC2s and IL-13 on maturation and proliferation of SPEM cells.MethodsWe performed single-cell RNA sequencing to characterize Meta1 gastroids,which were derived from stomachs of Mist1-Kras transgenic mice that displayed pyloric metaplasia. Cell sorting was used to isolate activated ILC2s from stomachs of IL-13-tdTomato reporter mice treated with L635. Three-dimensional co-culture was used to determine the effects of ILC2s on Meta1 gastroids. Mouse normal or metaplastic (Meta1) and human metaplastic gastroids were cultured with IL-13 to evaluate cell responses. Air-Liquid Interface culture was performed to test long-term culture effects of IL-13. In silico analysis determined possible STAT6-binding sites in gene promoter regions. STAT6 inhibition was performed to corroborate STAT6 role in SPEM cells maturation.ResultsMeta1 gastroids showed the characteristics of SPEM cell lineages in vitro even after several passages. We demonstrated that co-culture with ILC2s or IL-13 treatment can induce phosphorylation of STAT6 in Meta1 and normal gastroids and promote the maturation and proliferation of SPEM cell lineages. IL-13 up-regulated expression of mucin-related proteins in human metaplastic gastroids. Inhibition of STAT6 blocked SPEM-related gene expression in Meta1 gastroids and maturation of SPEM in both normal and Meta1 gastroids.ConclusionsIL-13 promotes the maturation and proliferation of SPEM cells consistent with gastric mucosal regeneration. Graphical Abstract 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

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

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