Nanog-Tcf15 axis during exit from naïve pluripotency

Pluripotent cells have the dual abilities to self-renewal and to differentiate into all three germ layers. Pluripotent cells can be isolated from two different stages of mouse embryogenesis. Embryonic stem cells (ESCs) are isolated from the inner cell mass (ICM) of the pre-implantation embryo and are considered to be in a naïve state. On the other hand, cells isolated from epiblast of the post-implantation embryo are referred as epiblast stem cells (EpiSC) and are representative of primed pluripotency. ESCs and EpiSCs are distinct from each other in terms of the morphology, the gene regulatory network and the signalling pathways regulating self-renewal. Under certain conditions, ESCs and EpiSCs can be transitioned into each other. However, the mechanism that regulates this transition from naïve to primed pluripotent state remains to be solved. Nanog, Oct4 and Sox2 form the core gene regulatory network of pluripotency. Additionally, the Id protein family is also important in the maintenance of pluripotency in ESCs. Id proteins function by inhibiting the activity of pro-differentiation factors. Tcf15 is identified as one of the targets of Id inhibition in ESCs. Moreover, Tcf15 has been identified as a repression target of Nanog. In this study, to understand the function of Tcf15, the expression of Tcf15 was characterized in differentiating ESCs. The transient upregulation of Tcf15 mRNA and protein was detected at early stages of differentiation before lineage commitment. Furthermore, Tcf15 protein was heterogeneously expressed in differentiating cells. Mutually exclusive expression of Nanog and Tcf15 proteins were demonstrated in both self-renewing and differentiating ESCs. Further characterization of the effect of Nanog on Tcf15 transcription showed that Tcf15 pre-mRNA was downregulated within 20 minute of Nanog induction. A Nanog binding site was identified at +32kb relative to the Tcf15 transcription start site (TSS). Initially, Nanog binding at this region was confirmed by performing ChIP-PCR experiments. Then, this Nanog binding region was further analysed for its enhancer activity related to the Tcf15 gene. Deletion of the Nanog binding region using CRISPR-Cas9 confirmed that this region acts as Tcf15 enhancer; it was shown that this region was required for the activation of Tcf15 transcription during differentiation. Tcf15 induction experiments were performed in order to the check whether Tcf15 affects Nanog transcription. The results indicate that Nanog is not a direct target of Tcf15, but Tcf15 contributes indirectly to the repression of Nanog. Additional analysis with the Tcf15 enhancer deletion cells showed that Tcf15 is not required for efficient downregulation of naïve markers and the upregulation of primed markers. However, the genes related to the regulation of adhesion properties of cells such as Zyc, Itga3 were induced with lower efficiency in the absence of Tcf15 compared to the wild type cells. In summary, I investigated the reciprocal regulation of Tcf15 and Nanog and the role of Tcf15 for the differentiation. My results suggest that Tcf15 is expressed in the cells that have initiated differentiation but are not lineage-committed. Additionally, Tcf15 can contribute to the regulation of adhesion related genes in order to help the epithelisation of the cells required during the differentiation from naïve to the primed pluripotent state. As a conclusion, Nanog is proposed to help to prevent certain aspects of ESCs differentiation by repressing Tcf15

Immunization status in chronic obstructive pulmonary disease: A multicenter study from Turkey

intepe, yavuz selim/0000-0002-5697-5291; Erol, Serhat/0000-0003-1645-7761; Korkmaz, Celalettin/0000-0001-8602-0368; Sertogullarindan, Bunyamin/0000-0002-1478-1990; Kasapoglu, Umut Sabri/0000-0003-2869-9872; Bulbul, Yilmaz/0000-0002-8488-3650WOS: 000455908800007PubMed: 30745939OBJECTIVE: The purpose of this study is to detect the prevalence and the factors associated with influenza and pneumococcal vaccination and outcomes of vaccination during 2013-2014 season in patients with chronic obstructive pulmonary disease (COPD) in Turkey. METHODS: This was a multicenter retrospective cohort study performed in 53 different centers in Turkey. RESULTS: During the study period, 4968 patients were included. COPD was staged as GOLD 1-2-3-4 in 9.0%, 42.8%, 35.0%, and 13.2% of the patients, respectively. Influenza vaccination rate in the previous year was 37.9%; and pneumococcus vaccination rate, at least once during in a life time, was 13.3%. Patients with older age, higher level of education, more severe COPD, and comorbidities, ex-smokers, and patients residing in urban areas had higher rates of influenza vaccination. Multivariate logistic regression analysis showed that advanced age, higher education levels, presence of comorbidities, higher COPD stages, and exacerbation rates were associated with both influenza and pneumococcal vaccination. The number of annual physician/outpatient visits and hospitalizations due to COPD exacerbation was 2.73 +/- 2.85 and 0.92 +/- 1.58 per year, respectively. Patients with older age, lower education levels, more severe COPD, comorbid diseases, and lower body mass index and patients who are male and are residing in rural areas and vaccinated for influenza had significantly higher rates of COPD exacerbation. CONCLUSIONS: The rates of influenza and pneumococcal vaccination in COPD patients were quite low, and the number of annual physician/outpatient visits and hospitalizations due to COPD exacerbation was high in Turkey. Advanced age, higher education levels, comorbidities, and higher COPD stages were associated with both influenza and pneumococcal vaccination

MPP8 is essential for sustaining self-renewal of ground-state pluripotent stem cells

Deciphering the mechanisms that control the pluripotent ground state is key for understanding embryonic development. Nonetheless, the epigenetic regulation of ground-state mouse embryonic stem cells (mESCs) is not fully understood. Here, we identify the epigenetic protein MPP8 as being essential for ground-state pluripotency. Its depletion leads to cell cycle arrest and spontaneous differentiation. MPP8 has been suggested to repress LINE1 elements by recruiting the human silencing hub (HUSH) complex to H3K9me3-rich regions. Unexpectedly, we find that LINE1 elements are efficiently repressed by MPP8 lacking the chromodomain, while the unannotated C-terminus is essential for its function. Moreover, we show that SETDB1 recruits MPP8 to its genomic target loci, whereas transcriptional repression of LINE1 elements is maintained without retaining H3K9me3 levels. Taken together, our findings demonstrate that MPP8 protects the DNA-hypomethylated pluripotent ground state through its association with the HUSH core complex, however, independently of detectable chromatin binding and maintenance of H3K9me3

TAK1 inhibition leads to RIPK1-dependent apoptosis in immune-activated cancers

Poor survival and lack of treatment response in glioblastoma (GBM) is attributed to the persistence of glioma stem cells (GSCs). To identify novel therapeutic approaches, we performed CRISPR/Cas9 knockout screens and discovered TGFβ activated kinase (TAK1) as a selective survival factor in a significant fraction of GSCs. Loss of TAK1 kinase activity results in RIPK1-dependent apoptosis via Caspase-8/FADD complex activation, dependent on autocrine TNFα ligand production and constitutive TNFR signaling. We identify a transcriptional signature associated with immune activation and the mesenchymal GBM subtype to be a characteristic of cancer cells sensitive to TAK1 perturbation and employ this signature to accurately predict sensitivity to the TAK1 kinase inhibitor HS-276. In addition, exposure to pro-inflammatory cytokines IFN gamma and TNFα can sensitize resistant GSCs to TAK1 inhibition. Our findings reveal dependency on TAK1 kinase activity as a novel vulnerability in immune-activated cancers, including mesenchymal GBMs that can be exploited therapeutically