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

The T-cell receptor (TCR) initiates T-lymphocyte activation,but the mechanism of TCR activation remains uncertain. Here,we present cryogenic electron microscopy structures for the unliganded and human leukocyte antigen (HLA)-bound human TCR–CD3 complex in nanodiscs that provide a native-like lipid environment. Distinct from the open and extended conformation seen in detergent,the unliganded TCR–CD3 in nanodiscs adopts two related closed and compacted conformations that represent its physiologic resting state in vivo. By contrast,the HLA-bound complex adopts the open and extended conformation,and conformation-locking disulfide mutants show that ectodomain opening is necessary for maximal ligand-dependent T-cell activation. These structures also reveal conformation-dependent protein–lipid and glycan–glycan interactions within the TCR. Together,these results establish allosteric conformational change during TCR activation,reveal avenues for immunotherapeutic engineering,and highlight the importance of native-like lipid environments for membrane protein structure determination. The T-cell receptor (TCR) activation mechanism has remained uncertain. Here,the authors present molecular structures for the apo and ligand-bound human TCR–CD3 complex in lipid nanodiscs,revealing large conformational changes during activation. View Publication

In order to develop a novel method of visualizing possible Ca(2+) signaling during the early differentiation of hESCs into cardiomyocytes and avoid some of the inherent problems associated with using fluorescent reporters,we expressed the bioluminescent Ca(2+) reporter,apo-aequorin,in HES2 cells and then reconstituted active holo-aequorin by incubation with f-coelenterazine. The temporal nature of the Ca(2+) signals generated by the holo-f-aequorin-expressing HES2 cells during the earliest stages of differentiation into cardiomyocytes was then investigated. Our data show that no endogenous Ca(2+) transients (generated by release from intracellular stores) were detected in 1-12-day-old cardiospheres but transients were generated in cardiospheres following stimulation with KCl or CaCl2,indicating that holo-f-aequorin was functional in these cells. Furthermore,following the addition of exogenous ATP,an inositol trisphosphate receptor (IP3R) agonist,small Ca(2+) transients were generated from day 1 onward. That ATP was inducing Ca(2+) release from functional IP3Rs was demonstrated by treatment with 2-APB,a known IP3R antagonist. In contrast,following treatment with caffeine,a ryanodine receptor (RyR) agonist,a minimal Ca(2+) response was observed at day 8 of differentiation only. Thus,our data indicate that unlike RyRs,IP3Rs are present and continually functional at these early stages of cardiomyocyte differentiation. View Publication

Individual variation in fetal hemoglobin (HbF,alpha(2)gamma(2)) response underlies the remarkable diversity in phenotypic severity of sickle cell disease and beta thalassemia. HbF levels and HbF-associated quantitative traits (e.g.,F cell levels) are highly heritable. We have previously mapped a major quantitative trait locus (QTL) controlling F cell levels in an extended Asian-Indian kindred with beta thalassemia to a 1.5-Mb interval on chromosome 6q23,but the causative gene(s) are not known. The QTL encompasses several genes including HBS1L,a member of the GTP-binding protein family that is expressed in erythroid progenitor cells. In this high-resolution association study,we have identified multiple genetic variants within and 5' to HBS1L at 6q23 that are strongly associated with F cell levels in families of Northern European ancestry (P = 10(-75)). The region accounts for 17.6% of the F cell variance in northern Europeans. Although mRNA levels of HBS1L and MYB in erythroid precursors grown in vitro are positively correlated,only HBS1L expression correlates with high F cell alleles. The results support a key role for the HBS1L-related genetic variants in HbF control and illustrate the biological complexity of the mechanism of 6q QTL as a modifier of fetal hemoglobin levels in the beta hemoglobinopathies. View Publication

PurposeOxaliplatin-induced peripheral neuropathy (OIPN) is a chronic,debilitating late effect following oxaliplatin treatment. Neurofilament light chain (NfL) is a structural protein found in nerve axons that was investigated upon oxaliplatin exposure in vitro and in vivo correlated to symptoms of OIPN in colorectal cancer patients receiving oxaliplatin.MethodsHuman sensory neurons,derived from induced pluripotent stem cells,were exposed to clinically relevant concentrations of oxaliplatin in vitro,with NfL concentrations measured in the cell medium. The prospective clinical study included patients with colorectal cancer undergoing chemotherapy therapy with or without oxaliplatin. Possible OIPN was defined as bilateral presence of numbness and/or presence of pricking sensations in the feet documented in an interview at the time of blood sampling prior to,3,and 6 months after initiating treatment.ResultsOxaliplatin exposure led to a dose-dependent NfL increase in vitro. In the clinical cohort of 30 patients (18 in the oxaliplatin group),NfL levels rose at 3 and 6 months compared to controls. NfL level changes correlated to OIPN symptoms at the 6-month timepoint (rho 0.81,p? View Publication

MEK/ERK signaling plays a crucial role in a diverse set of cellular functions including cell proliferation,differentiation and survival,and recently has been reported to negatively regulate mouse embryonic stem cell (mESC) self-renewal by antagonizing STAT3 activity. However,its role in human ESCs (hESCs) remains unclear. Here we investigated the functions of MEK/ERK in controlling hESC activity. We demonstrated that MEK/ERK kinases were targets of fibroblast growth factor (FGF) pathway in hESCs. Surprisingly,we found that,in contrast to mESCs,high basal MEK/ERK activity was required for maintaining hESCs in an undifferentiated state. Inhibition of MEK/ERK activity by specific MEK inhibitors PD98059 and U0126,or by RNA interference,rapidly caused the loss of self-renewal capacity. We also showed that MEK/ERK signaling cooperated with phosphoinositide 3-kinase (PI3K)/AKT signaling in maintaining hESC pluripotency. However,MEK/ERK signaling had little or no effect on regulating hESC proliferation and survival,in contrast to PI3K/AKT signaling. Taken together,these findings reveal the unique and crucial role of MEK/ERK signaling in the determination of hESC cell fate and expand our understanding of the molecular mechanisms behind the FGF pathway maintenance of hESC pluripotency. Importantly,these data make evident the striking differences in the control of self-renewal between hESCs and mESCs. View Publication

Sirtuins are NAD(+)-dependent protein deacetylases and are emerging as molecular targets for the development of pharmaceuticals to treat human metabolic and neurological diseases and cancer. To date,several sirtuin inhibitors and activators have been identified,but the structural mechanisms of how these compounds modulate sirtuin activity have not yet been determined. We identified suramin as a compound that binds to human SIRT5 and showed that it inhibits SIRT5 NAD(+)-dependent deacetylase activity with an IC(50) value of 22 microM. To provide insights into how sirtuin function is altered by inhibitors,we determined two crystal structures of SIRT5,one in complex with ADP-ribose,the other bound to suramin. Our structural studies provide a view of a synthetic inhibitory compound in a sirtuin active site revealing that suramin binds into the NAD(+),the product,and the substrate-binding site. Finally,our structures may enable the rational design of more potent inhibitors. View Publication

STUDY QUESTION Can human embryonic stem cell-derived trophoblastic spheroids be used to study the early stages of implantation? SUMMARY ANSWER We generated a novel human embryonic stem cell-derived trophoblastic spheroid model mimicking human blastocysts in the early stages of implantation. WHAT IS KNOWN ALREADY Both human embryos and choriocarcinoma cell line derived spheroids can attach onto endometrial cells and are used as models to study the early stages of implantation. However,human embryos are limited and the use of cancer cell lines for spheroid generation remains sub-optimal for research. STUDY DESIGN,SIZE,DURATION Experimental induced differentiation of human embryonic stem cells into trophoblast and characterization of the trophoblast. PARTICIPANTS/MATERIALS,SETTING,METHODS Trophoblastic spheroids (BAP-EB) were generated by inducing differentiation of a human embryonic stem cell line,VAL3 cells with bone morphogenic factor-4,A83-01 (a TGF-$\$),and PD173074 (a FGF receptor-3 inhibitor) after embryoid body formation. The expressions of trophoblastic markers and hCG levels were studied by real-time PCR and immunohistochemistry. BAP-EB attachment and invasion assays were performed on different cell lines and primary endometrial cells. MAIN RESULTS AND THE ROLE OF CHANCE After 48 h of induced differentiation,the BAP-EB resembled early implanting human embryos in terms of size and morphology. The spheroids derived from embryonic stem cells (VAL3),but not from several other cell lines studied,possessed a blastocoel-like cavity. BAP-EB expressed several markers of trophectoderm of human blastocysts on Day 2 of induced differentiation. In the subsequent days of differentiation,the cells of the spheroids differentiated into trophoblast-like cells expressing trophoblastic markers,though at levels lower than that in the primary trophoblasts or in a choriocarcinoma cell line. On Day 3 of induced differentiation,BAP-EB selectively attached onto endometrial epithelial cells,but not other non-endometrial cell lines or an endometrial cell line that had lost its epithelial character. The attachment rates of BAP-EB was significantly higher on primary endometrial epithelial cells (EEC) taken from 7 days after hCG induction of ovulation (hCG+7 day) when compared with that from hCG+2 day. The spheroids also invaded through Ishikawa cells and the primary endometrial stromal cells in the co-culture. LIMITATIONS,REASONS FOR CAUTION The attachment rates of BAP-EB were compared between EEC obtained from Day 2 and Day 7 of the gonadotrophin stimulated cycle,but not the natural cycles. WIDER IMPLICATIONS OF THE FINDINGS BAP-EB have the potential to be used as a test for predicting endometrial receptivity in IVF cycles and provide a novel approach to study early human implantation,trophoblastic cell differentiation and trophoblastic invasion into human endometrial cells. View Publication

BACKGROUND Cytotoxic T lymphocyte antigen-4 (CTLA-4) limits T-cell activation and is expressed on T-regulatory cells. Human CTLA-4 deficiency results in severe immune dysregulation. Abatacept (CTLA-4 Ig) is approved for the treatment of rheumatoid arthritis (RA) and its mechanism of action is attributed to effects on T-cells. It is known that CTLA-4 modulates the expression of its ligands CD80 and CD86 on antigen presenting cells (APC) by transendocytosis. As B-cells express CD80/CD86 and function as APC,we hypothesize that B-cells are a direct target of abatacept. OBJECTIVES To investigate direct effects of abatacept on human B-lymphocytes in vitro and in RA patients. METHODS The effect of abatacept on healthy donor B-cells' phenotype,activation and CD80/CD86 expression was studied in vitro. Nine abatacept-treated RA patients were studied. Seven of these were followed up to 24 months,and two up to 12 months only and treatment response,immunoglobulins,ACPA,RF concentrations,B-cell phenotype and ACPA-specific switched memory B-cell frequency were assessed. RESULTS B-cell development was unaffected by abatacept. Abatacept treatment resulted in a dose-dependent decrease of CD80/CD86 expression on B-cells in vitro,which was due to dynamin-dependent internalization. RA patients treated with abatacept showed a progressive decrease in plasmablasts and serum IgG. While ACPA-titers only moderately declined,the frequency of ACPA-specific switched memory B-cells significantly decreased. CONCLUSIONS Abatacept directly targets B-cells by reducing CD80/CD86 expression. Impairment of antigen presentation and T-cell activation may result in altered B-cell selection,providing a new therapeutic mechanism and a base for abatacept use in B-cell mediated autoimmunity. View Publication

The purpose of this study is to characterize the microRNA (miRNA) expression profiles of induced pluripotent stem (iPS) cells and retinal pigment epithelium (RPE) derived from induced pluripotent stem cells (iPS-RPE). MiRNAs have been demonstrated to play critical roles in both maintaining pluripotency and facilitating differentiation. Gene expression networks accountable for maintenance and induction of pluripotency are linked and share components with those networks implicated in oncogenesis. Therefore,we hypothesize that miRNA expression profiling will distinguish iPS cells from their iPS-RPE progeny. To identify and analyze differentially expressed miRNAs,RPE was derived from iPS using a spontaneous differentiation method. MiRNA microarray analysis identified 155 probes that were statistically differentially expressed between iPS and iPS-RPE cells. Up-regulated miRNAs including miR-181c and miR-129-5p may play a role in promoting differentiation,while down-regulated miRNAs such as miR-367,miR-18b,and miR-20b are implicated in cell proliferation. Subsequent miRNA-target and network analysis revealed that these miRNAs are involved in cellular development,cell cycle progression,cell death,and survival. A systematic interrogation of temporal and spatial expression of iPS-RPE miRNAs and their associated target mRNAs will provide new insights into the molecular mechanisms of carcinogenesis,eye differentiation and development. View Publication

BackgroundMetastasis,the spread,and growth of malignant cells at secondary sites within a patient’s body,accounts for over 90% of cancer-related mortality. Breast cancer is the most common tumor type diagnosed and the leading cause of cancer lethality in women in the United States. It is estimated that 10–16% breast cancer patients will have brain metastasis. Current therapies to treat patients with breast cancer brain metastasis (BCBM) remain palliative. This is largely due to our limited understanding of the fundamental molecular and cellular mechanisms through which BCBM progresses,which represents a critical barrier for the development of efficient therapies for affected breast cancer patients.MethodsPrevious research in BCBM relied on co-culture assays of tumor cells with rodent neural cells or rodent brain slice ex vivo. Given the need to overcome the obstacle for human-relevant host to study cell-cell communication in BCBM,we generated human embryonic stem cell-derived cerebral organoids to co-culture with human breast cancer cell lines. We used MDA-MB-231 and its brain metastatic derivate MDA-MB-231 Br-EGFP,other cell lines of MCF-7,HCC-1806,and SUM159PT. We leveraged this novel 3D co-culture platform to investigate the crosstalk of human breast cancer cells with neural cells in cerebral organoid.ResultsWe found that MDA-MB-231 and SUM159PT breast cancer cells formed tumor colonies in human cerebral organoids. Moreover,MDA-MB-231 Br-EGFP cells showed increased capacity to invade and expand in human cerebral organoids.ConclusionsOur co-culture model has demonstrated a remarkable capacity to discern the brain metastatic ability of human breast cancer cells in cerebral organoids. The generation of BCBM-like structures in organoid will facilitate the study of human tumor microenvironment in culture. View Publication

ABSTRACTProneural genes are conserved drivers of neurogenesis across the animal kingdom. How their functions have adapted to guide human-specific neurodevelopmental features is poorly understood. Here,we mined transcriptomic data from human fetal cortices and generated from human embryonic stem cell-derived cortical organoids (COs) to show that NEUROG1 and NEUROG2 are most highly expressed in basal neural progenitor cells,with pseudotime trajectory analyses indicating that NEUROG1-derived lineages predominate early and NEUROG2 lineages later. Using ChIP-qPCR,gene silencing and overexpression studies in COs,we show that NEUROG2 is necessary and sufficient to directly transactivate known target genes (NEUROD1,EOMES,RND2). To identify new targets,we engineered NEUROG2-mCherry knock-in human embryonic stem cells for CO generation. The mCherry-high CO cell transcriptome is enriched in extracellular matrix-associated genes,and two genes associated with human-accelerated regions: PPP1R17 and FZD8. We show that NEUROG2 binds COL1A1,COL3A1 and PPP1R17 regulatory elements,and induces their ectopic expression in COs,although NEUROG2 is not required for this expression. Neurog2 similarly induces Col3a1 and Ppp1r17 in murine P19 cells. These data are consistent with a conservation of NEUROG2 function across mammalian species. Summary: Analysis of human cortical organoids reveals that NEUROG1 lineages prevail early and NEUROG2 lineages later,and that NEUROG2 targets include COL genes and PPP1R17,a human-accelerated region-associated gene. View Publication

SUMMARY Elevated interferon (IFN) signaling is associated with kidney diseases including COVID-19,HIV,and apolipoprotein-L1 (APOL1) nephropathy,but whether IFNs directly contribute to nephrotoxicity remains unclear. Using human kidney organoids,primary endothelial cells,and patient samples,we demonstrate that IFN-? induces pyroptotic angiopathy in combination with APOL1 expression. Single-cell RNA sequencing,immunoblotting,and quantitative fluorescence-based assays reveal that IFN-?-mediated expression of APOL1 is accompanied by pyroptotic endothelial network degradation in organoids. Pharmacological blockade of IFN-? signaling inhibits APOL1 expression,prevents upregulation of pyroptosis-associated genes,and rescues vascular networks. Multiomic analyses in patients with COVID-19,proteinuric kidney disease,and collapsing glomerulopathy similarly demonstrate increased IFN signaling and pyroptosis-associated gene expression correlating with accelerated renal disease progression. Our results reveal that IFN-? signaling simultaneously induces endothelial injury and primes renal cells for pyroptosis,suggesting a combinatorial mechanism for APOL1-mediated collapsing glomerulopathy,which can be targeted therapeutically. In brief Juliar et al. address interferon signaling in kidney disease. Organoids,primary cells,and clinical datasets reveal that interferon signaling simultaneously induces APOL1 expression and endothelial cell pyroptosis. This suggests a combinatorial mechanism for APOL1-mediated collapsing glomerulopathy,which can be targeted therapeutically. The findings may also be relevant in other organs. Graphical Abstract View Publication