搜索结果: 'methocult media formulations for human hematopoietic cells serum containing'

Stem cells exist in vitro in a spectrum of interconvertible pluripotent states. Analyzing hundreds of hiPSCs derived from different individuals,we show the proportions of these pluripotent states vary considerably across lines. We discover 13 gene network modules (GNMs) and 13 regulatory network modules (RNMs),which are highly correlated with each other suggesting that the coordinated co-accessibility of regulatory elements in the RNMs likely underlie the coordinated expression of genes in the GNMs. Epigenetic analyses reveal that regulatory networks underlying self-renewal and pluripotency are more complex than previously realized. Genetic analyses identify thousands of regulatory variants that overlapped predicted transcription factor binding sites and are associated with chromatin accessibility in the hiPSCs. We show that the master regulator of pluripotency,the NANOG-OCT4 Complex,and its associated network are significantly enriched for regulatory variants with large effects,suggesting that they play a role in the varying cellular proportions of pluripotency states between hiPSCs. Our work bins tens of thousands of regulatory elements in hiPSCs into discrete regulatory networks,shows that pluripotency and self-renewal processes have a surprising level of regulatory complexity,and suggests that genetic factors may contribute to cell state transitions in human iPSC lines. Stem cells exist in vitro in a spectrum of interconvertible pluripotent states. Here,authors show that pluripotency and self-renewal processes have a high level of regulatory complexity and suggest that genetic factors contribute to cell state transitions in human iPSC lines. View Publication

Oligodendrocytes are the myelinating cells of the central nervous system. Regulation of the early stages of oligodendrocyte development is critical to the function of the cell. Specifically,myelin sheath formation is an energetically demanding event that requires precision,as alterations may lead to dysmyelination. Fatty acid β‐oxidation has been shown to be critical for the function of oligodendrocytes. We previously showed that myeloid cell leukemia‐1 (MCL‐1),a well‐characterized anti‐apoptotic protein,is required for the development of murine oligodendrocytes in vivo. Further,MCL‐1 regulates long‐chain fatty acid β‐oxidation in cancer cells through its interaction with Acyl‐CoA synthetase long‐chain family member 1 (ACSL1),an enzyme responsible for the conversion of free long‐chain fatty acids into fatty acyl‐CoA esters. Here,we introduce an in vitro system to isolate human stem cell‐derived oligodendrocyte progenitor cells (OPCs) and investigate the involvement of MCL‐1 during human oligodendrocyte development. Using this system,we pharmacologically inhibited MCL‐1 in OPCs to investigate its non‐apoptotic function at this developmental stage. We also used a motor neuron‐oligodendrocyte co‐culture system to examine the downstream effects of MCL‐1 at later developmental stages when oligodendrocytes begin to contact axons and generate myelin. We demonstrate that the mitochondrial network changes in human oligodendrocyte development resemble those reported in mouse tissue. Our findings point to MCL‐1 as a critical factor essential for proper oligodendrocyte morphogenesis. A unified model of oligodendrocyte differentiation from human embryonic stem cells revealed that MCL‐1 is critical for regulating the expression of oligodendrocyte‐related genes and the morphogenesis of myelinating oligodendrocytes. View Publication

Pharmacological inhibitors of glycogen synthase kinase-3 (GSK-3) and cyclin-dependent kinases have a promising potential for applications against several neurodegenerative diseases such as Alzheimer's disease. Indirubins,a family of bis-indoles isolated from various natural sources,are potent inhibitors of several kinases,including GSK-3. Using the cocrystal structures of various indirubins with GSK-3beta,CDK2 and CDK5/p25,we have modeled the binding of indirubins within the ATP-binding pocket of these kinases. This modeling approach provided some insight into the molecular basis of indirubins' action and selectivity and allowed us to forecast some improvements of this family of bis-indoles as kinase inhibitors. Predicted molecules,including 6-substituted and 5,6-disubstituted indirubins,were synthesized and evaluated as CDK and GSK-3 inhibitors. Control,kinase-inactive indirubins were obtained by introduction of a methyl substitution on N1. View Publication

The significant advances in the differentiation of human pluripotent stem (hPS) cells into pancreatic endocrine cells,including functional ?-cells,have been based on a detailed understanding of the underlying developmental mechanisms. However,the final differentiation steps,leading from endocrine progenitors to mono-hormonal and mature pancreatic endocrine cells,remain to be fully understood and this is reflected in the remaining shortcomings of the hPS cell-derived islet cells (SC-islet cells),which include a lack of ?-cell maturation and variability among different cell lines. Additional signals and modifications of the final differentiation steps will have to be assessed in a combinatorial manner to address the remaining issues and appropriate reporter lines would be useful in this undertaking. Here we report the generation and functional validation of hPS cell reporter lines that can monitor the generation of INS+ and GCG+ cells and their resolution into mono-hormonal cells (INSeGFP,INSeGFP/GCGmCHERRY) as well as ?-cell maturation (INSeGFP/MAFAmCHERRY) and function (INSGCaMP6). The reporter hPS cell lines maintained strong and widespread expression of pluripotency markers and differentiated efficiently into definitive endoderm and pancreatic progenitor (PP) cells. PP cells from all lines differentiated efficiently into islet cell clusters that robustly expressed the corresponding reporters and contained glucose-responsive,insulin-producing cells. To demonstrate the applicability of these hPS cell reporter lines in a high-content live imaging approach for the identification of optimal differentiation conditions,we adapted our differentiation procedure to generate SC-islet clusters in microwells. This allowed the live confocal imaging of multiple SC-islets for a single condition and,using this approach,we found that the use of the N21 supplement in the last stage of the differentiation increased the number of monohormonal ?-cells without affecting the number of ?-cells in the SC-islets. The hPS cell reporter lines and the high-content live imaging approach described here will enable the efficient assessment of multiple conditions for the optimal differentiation and maturation of SC-islets. View Publication

Immunotherapy has emerged as a key modality in cancer treatment,yet its effectiveness varies significantly among patients,often due to the metabolic stress imposed by the tumor microenvironment. Hypoxia,a major factor in the tumor microenvironment,results from the high metabolic rate of tumor cells and inadequate vascularization,impairing immune cells’ function and potentially influencing gene expression profiles. Despite the widespread use of quantitative real-time PCR in immunological studies,to the best of our knowledge,data on reference gene stability in human peripheral blood mononuclear cells under hypoxic conditions is limited. In our study,we assessed the expression stability of commonly used reference genes ( S18,HPRT,IPO8,RPL13A,SDHA,PPIA,and UBE2D2 ) in both non-stimulated and CD3/CD28-activated peripheral blood mononuclear cells cultured under normoxic,hypoxic (1% O 2 ),and chemically induced hypoxic conditions for 24 h. Analysis using four different algorithms—delta Ct,geNorm,NormFinder,and BestKeeper—identified RPL13A,S18,and SDHA as the most suitable reference genes for human peripheral blood mononuclear cells under hypoxic conditions. In contrast,IPO8 and PPIA were found to be the least suitable housekeeping genes. The study provides essential insights into the stability of reference genes in peripheral blood mononuclear cells under hypoxic conditions,a critical but understudied aspect of immunological research. Given the significant impact of hypoxia on T cell metabolism and function in the tumor microenvironment,selecting reliable reference genes is crucial for accurate gene expression analysis. Our findings will be valuable for future studies investigating hypoxia-driven metabolic reprogramming in immune cells,ultimately contributing to a better understanding of T cell responses in cancer immunotherapy. View Publication

Deregulation of apoptosis,the physiological form of cell death,is closely associated with immunological diseases and cancer. Apoptosis is activated either by death receptor-driven or mitochondrial pathways,both of which may provide potential targets for novel anticancer drugs. Although several ligands stimulating death receptors have been described,the actual molecular events triggering the mitochondrial pathway are largely unknown. Here,we show initiation of apoptosis by gradual depletion of the intracellular coenzyme NAD+. We identified the first low molecular weight compound,designated FK866,which induces apoptosis by highly specific,noncompetitive inhibition of nicotinamide phosphoribosyltransferase (NAPRT),a key enzyme in the regulation of NAD+ biosynthesis from the natural precursor nicotinamide. Interference with this enzyme does not primarily intoxicate cells because the mitochondrial respiratory activity and the NAD+ -dependent redox reactions involved remain unaffected as long as NAD+ is not effectively depleted by catabolic reactions. Certain tissues,however,have a high turnover of NAD+ through its cleavage by enzymes like poly(ADP-ribose) polymerase. Such cells often rely on the more readily available nicotinamide pathway for NAD+ synthesis and undergo apoptosis after inhibition of NAPRT,whereas cells effectively using the nicotinic acid pathway for NAD+ synthesis remain unaffected. In support of this concept,FK866 effectively induced delayed cell death by apoptosis in HepG2 human liver carcinoma cells with an IC(50) of approximately 1 nM,did not directly inhibit mitochondrial respiratory activity,but caused gradual NAD+ depletion through specific inhibition of NAPRT. This enzyme,when partially purified from K562 human leukemia cells,was noncompetitively inhibited by FK866,and the inhibitor constants were calculated to be 0.4 nM for the enzyme/substrate complex (K(i)) and 0.3 nM for the free enzyme (K(i)'),respectively. Nicotinic acid and nicotinamide were both found to have antidote potential for the cellular effects of FK866. FK866 may be used for treatment of diseases implicating deregulated apoptosis such as cancer for immunosuppression or as a sensitizer for genotoxic agents. Furthermore,it may provide an important tool for investigation of the molecular triggers of the mitochondrial pathway leading to apoptosis through enabling temporal separation of NAD+ decrease from ATP breakdown and apoptosis by several days. View Publication

In neuronal growth cones,the advancing tips of elongating axons and dendrites,specific protein substrates appear to undergo cycles of posttranslational modification by covalent attachment and removal of long-chain fatty acids. We show here that ongoing fatty acylation can be inhibited selectively by long-chain homologues of the antibiotic tunicamycin,a known inhibitor of N-linked glycosylation. Tunicamycin directly inhibits transfer of palmitate to protein in a cell-free system,indicating that tunicamycin inhibition of protein palmitoylation reflects an action of the drug separate from its previously established effects on glycosylation. Tunicamycin treatment of differentiated PC12 cells or dissociated rat sensory neurons,under conditions in which protein palmitoylation is inhibited,produces a prompt cessation of neurite elongation and induces a collapse of neuronal growth cones. These growth cone responses are rapidly reversed by washout of the antibiotic,even in the absence of protein synthesis,or by addition of serum. Two additional lines of evidence suggest that the effects of tunicamycin on growth cones arise from its ability to inhibit protein long-chain acylation,rather than its previously established effects on protein glycosylation and synthesis. (a) The abilities of different tunicamycin homologues to induce growth cone collapse very systematically with the length of the fatty acyl side-chain of tunicamycin,in a manner predicted and observed for the inhibition of protein palmitoylation. Homologues with fatty acyl moieties shorter than palmitic acid (16 hydrocarbons),including potent inhibitors of glycosylation,are poor inhibitors of growth cone function. (b) The tunicamycin-induced impairment of growth cone function can be reversed by the addition of excess exogenous fatty acid,which reverses the inhibition of protein palmitoylation but has no effect on the inhibition of protein glycosylation. These results suggest an important role for dynamic protein acylation in growth cone-mediated extension of neuronal processes. View Publication

The synthetic retinoid 6-[3-(adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437),which can bind to and activate the nuclear retinoic acid receptors beta and gamma (RARbeta/gamma),is a potent inducer of apoptosis in various cancer cell lines. However,this effect was reported to be independent of RARs. In this study,we compared and contrasted the potencies and mechanisms of action of CD437 and several other receptor-selective retinoids in induction of apoptosis and modulation of squamous differentiation in UMSCC22B human head and neck squamous cell carcinoma cell line. CD437 and the structurally related retinoid CD2325 exhibited almost equal potency in inducing apoptosis,whereas several other retinoids failed to induce apoptosis. The RAR-specific pan antagonist AGN193109 failed to suppress CD437-induced apoptosis,indicating that the induction of apoptosis by CD437 was RAR-independent. c-Fos expression was induced by CD437 and CD2325 that induced apoptosis in the cell line but not by other retinoids that failed to induce apoptosis,suggesting a role for c-Fos in CD437-induced apoptosis. At low concentration (0.01 microM),CD437 shared with several other receptor-selective retinoids the ability to suppress the mRNA levels of the squamous differentiation markers Spr1,involucrin,and cytokeratin 1. This effect of CD437 could be blocked by AGN193109. We conclude that CD437 can exert its effects in UMSCC22B human human head and neck squamous cell carcinoma cells by at least two mechanisms: RAR-mediated suppression of squamous differentiation and RAR-independent induction of apoptosis. View Publication

The reprogramming of somatic cells to pluripotency using defined transcription factors holds great promise for biomedicine. However,human reprogramming remains inefficient and relies either on the use of the potentially dangerous oncogenes KLF4 and CMYC or the genetic inhibition of the tumor suppressor gene p53. We hypothesized that inhibition of signal transduction pathways that promote differentiation of the target somatic cells during development might relieve the requirement for non-core pluripotency factors during induced pluripotent stem cell (iPSC) reprogramming. Here,we show that inhibition of Notch greatly improves the efficiency of iPSC generation from mouse and human keratinocytes by suppressing p21 in a p53-independent manner and thereby enriching for undifferentiated cells capable of long-term self-renewal. Pharmacological inhibition of Notch enabled routine production of human iPSCs without KLF4 and CMYC while leaving p53 activity intact. Thus,restricting the development of somatic cells by altering intercellular communication enables the production of safer human iPSCs. View Publication