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Although structurally unrelated,the human killer cell Ig-like (KIR) genes and the rodent lectin-like Ly49 genes serve similar functional roles in NK cells. Moreover,both gene families display variegated,monoallelic expression patterns established at the transcriptional level. DNA methylation has been shown to play an important role in maintenance of expression patterns of KIR genes,which have CpG island promoters. The potential role of DNA methylation in expression of Ly49 genes,which have CpG-poor promoters,is unknown. In this study,we show that hypomethylation of the region encompassing the Pro-2 promoter of Ly49a and Ly49c in primary C57BL/6 NK cells correlates with expression of the gene. Using C57BL/6 x BALB/c F1 hybrid mice,we demonstrate that the expressed allele of Ly49a is hypomethylated while the nonexpressed allele is heavily methylated,indicating a role for epigenetics in maintaining monoallelic Ly49 gene expression. Furthermore,the Ly49a Pro-2 region is heavily methylated in fetal NK cells but variably methylated in nonlymphoid tissues. Finally,in apparent contrast to the KIR genes,we show that DNA methylation and the histone acetylation state of the Pro-2 region are strictly linked with Ly49a expression status. View Publication

We re-examine the individual components for human embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) culture and formulate a cell culture system in which all protein reagents for liquid media,attachment surfaces and splitting are chemically defined. A major improvement is the lack of a serum albumin component,as variations in either animal- or human-sourced albumin batches have previously plagued human ESC and iPSC culture with inconsistencies. Using this new medium (E8) and vitronectin-coated surfaces,we demonstrate improved derivation efficiencies of vector-free human iPSCs with an episomal approach. This simplified E8 medium should facilitate both the research use and clinical applications of human ESCs and iPSCs and their derivatives,and should be applicable to other reprogramming methods. View Publication

Four monoclonal antibodies against antigens of human myeloid cells have been produced and thoroughly characterized in terms of their reactions with peripheral blood cells,cell lines,nine lymphoid and non-lymphoid tissues and the polypeptides with which they react. UCHM1 and SmO identify antigens present on the majority of blood monocytes and a variable,but lower,proportion of tissue macrophages. From their morphology and location in tissues,these cells appear to be recirculating monocytes. SMO antigen is also present on platelets. In addition,both antibodies stained endothelial cells,SMO in all tissues examined and UCHM1 variably. Biochemical investigation indicated that the UCHM1 antigen is a protein of 52,000 MW while the SMO antigen could not be indentified. The antibodies TG1 and 28 identify antigens mainly present on granulocytes. While mAb 28 reacted with neutrophils,TG1 also stained eosinophils and stained strongly a proportion of monocytes. TG1 also reacted variably with some non-haemopoietic cell lines. Both antibodies reacted predominantly with granulocytes in tissue sections. MAb TG1 precipitated a single polypeptide of 156,000 MW from monocytes and granulocytes,while mAb 28 precipitated non-convalently associated polypeptides of 83,000 and 155,000 MW from granulocytes but only a single molecule from monocytes,corresponding to the lower MW chain of 83,000. The epitope with which mAb 28 reacts appears not to be exposed on the surface of intact monocytes. This suggests that a similar or identical 83,000 MW molecule is made by both neutrophils and monocytes,but that its expression differs according to cell type. View Publication

As a critical immune checkpoint molecule,PD-L1 is expressed at significantly higher levels in multiple neoplastic tissues compared to normal ones. PD-L1/PD-1 axis is a critical target for tumor immunotherapy,blocking the PD-L1/PD-1 axis is recognized and has achieved unprecedented success in clinical applications. However,the clinical efficacy of therapies targeting the PD-1/PD-L1 pathway remains limited,emphasizing the need for the mechanistic elucidation of PD-1/PD-L1 expression. In this study,we found that RNF125 interacted with PD-L1 and regulated PD-L1 protein expression. Mechanistically,RNF125 promoted K48-linked polyubiquitination of PD-L1 and mediated its degradation. Notably,MC-38 and H22 cell lines with RNF125 knockout,transplanted in C57BL/6 mice,exhibited a higher PD-L1 level and faster tumor growth than their parental cell lines. In contrast,overexpression of RNF125 in MC-38 and H22 cells had the opposite effect,resulting in lower PD-L1 levels and delayed tumor growth compared with parental cell lines. In addition,immunohistochemical analysis of MC-38 tumors with RNF125 overexpression showed significantly increased infiltration of CD4+,CD8+ T cells and macrophages. Consistent with these findings,analyses using The Cancer Genome Atlas (TCGA) public database revealed a positive correlation of RNF125 expression with CD4+,CD8+ T cell and macrophage tumor infiltration. Moreover,RNF125 expression was significantly downregulated in several human cancer tissues,and was negatively correlated with the clinical stage of these tumors,and patients with higher RNF125 expression had better clinical outcomes. Our findings identify a novel mechanism for regulating PD-L1 expression and may provide a new strategy to increase the efficacy of immunotherapy. View Publication

The importance of early cancer diagnosis and improved cancer therapy has been clear for years and has initiated worldwide research towards new possibilities in the care strategy of patients with cancer using technological innovations. One of the key research fields involves the separation and detection of circulating tumor cells (CTC) because of their suggested important role in early cancer diagnosis and prognosis,namely,providing easy access by a liquid biopsy from blood to identify metastatic cells before clinically detectable metastasis occurs and to study the molecular and genetic profile of these metastatic cells. Provided the opportunity to further progress the development of technology for treating cancer,several CTC technologies have been proposed in recent years by various research groups and companies. Despite their potential role in cancer healthcare,CTC methods are currently mainly used for research purposes,and only a few methods have been accepted for clinical application because of the difficulties caused by CTC heterogeneity,CTC separation from the blood,and a lack of thorough clinical validation. Therefore,the standardization and clinical application of various developed CTC technologies remain important subsequent necessary steps. Because of their suggested future clinical benefits,we focus on describing technologies using whole blood samples without any pretreatment and discuss their advantages,use,and significance. Technologies using whole blood samples utilize size-based,immunoaffinity-based,and density-based methods or combinations of these methods as well as positive and negative enrichment during separation. Although current CTC technologies have not been truly implemented yet,they possess high potential as future clinical diagnostic techniques for the individualized therapy of patients with cancer. Thus,a detailed discussion of the clinical suitability of these new advanced technologies could help prepare clinicians for the future and can be a foundation for technologies that would be used to eliminate CTCs in vivo. View Publication

Neurotoxicity testing still relies on ethically debated,expensive and time consuming in vivo experiments,which are unsuitable for high-throughput toxicity screening. There is thus a clear need for a rapid in vitro screening strategy that is preferably based on human-derived neurons to circumvent interspecies translation. Recent availability of commercially obtainable human induced pluripotent stem cell (hiPSC)-derived neurons and astrocytes holds great promise in assisting the transition from the current standard of rat primary cortical cultures to an animal-free alternative. We therefore composed several hiPSC-derived neuronal models with different ratios of excitatory and inhibitory neurons in the presence or absence of astrocytes. Using immunofluorescent stainings and multi-well micro-electrode array (mwMEA) recordings we demonstrate that these models form functional neuronal networks that become spontaneously active. The differences in development of spontaneous neuronal activity and bursting behavior as well as spiking patterns between our models confirm the importance of the presence of astrocytes. Preliminary neurotoxicity assessment demonstrates that these cultures can be modulated with known seizurogenic compounds,such as picrotoxin (PTX) and endosulfan,and the neurotoxicant methylmercury (MeHg). However,the chemical-induced effects on different parameters for neuronal activity,such as mean spike rate (MSR) and mean burst rate (MBR),may depend on the ratio of inhibitory and excitatory neurons. Our results thus indicate that hiPSC-derived neuronal models must be carefully designed and characterized prior to large-scale use in neurotoxicity screening. View Publication