Project description:Insufficient understanding on cold adaptation technically restricts donor tissue banking. Here we identify FOXO1 as a conserved transcription factor for cell cold survival, relocating from cytosol to nucleus when temperature drops. FOXO1 small ubiquitin-like modifiers (SUMO) -interacting motif (SIM) antagonizes FOXO1-Importin-7 interaction regardless of temperature. At 37°C, SIM enhances FOXO1 interactions with SUMO E3 ligase RANBP2 and Exportin-1, FOXO1 hence cytoplasmic; at 4°C, FOXO1-Importin-7 interaction increases probably via RANBP2, making FOXO1 nuclear. These features enable fine-tuned FOXO1 regulations on chromatin folding and subsequent gene expression. Using these key factors as readouts, a ‘hibernation solution’ was developed, enabling long-term pancreatic islet cold storage and transplantation to cure diabetes. Henceforth, targeting FOXO1 SIM or the SUMO machinery may aid tissue/organ survival from long-term cold and other stresses.
Project description:Histone H1 variants, known as linker histones, are essential chromatin components in higher eukaryotes, yet compared to the core histones relatively little is known about their in vivo functions. The filamentous fungus Neurospora crassa encodes a single H1 protein that is not essential for viability. To investigate the role of N. crassa H1, we constructed a functional FLAG-tagged H1 fusion protein and performed genomic and molecular analyses. Cell fractionation experiments showed that H1-FLAG is a chromatin binding protein. Chromatin-immunoprecipitation combined with sequencing (ChIP-seq) revealed that H1-3XFLAG is globally enriched throughout the genome with a subtle preference for promoters of expressed genes. In mammals, the stochiometery of H1 impacts nucleosome repeat length. To determine if H1 impacts nucleosome occupancy or nucleosome positioning in N. crassa, we performed micrococcal nuclease digestion in wildtype and the ∆hH1 strain followed by sequencing (MNase-Seq). Deletion of hH1 did not significantly impact nucleosome positioning or nucleosome occupancy. Analysis of DNA methylation using methylC-sequencing (mC-Seq) revealed a modest but global increase in DNA methylation in the ∆hH1 mutant. Together, these data suggest that H1 acts as a non-specific chromatin binding protein that can limit accessibility of the DNA methylation machinery in N. crassa.
Project description:To explore the molecular mechanism underlying glucose regulation, we analyzed transcriptome changes in hepatic tissue after FOXO1 knockout.
Project description:Tight regulation of Toll-like receptor (TLR)-mediated inflammatory responses is important in innate immunity. Here, we show that T cell death-associated gene 51 (TDAG51/PHLDA1) is a novel coactivator of the transcription factor FoxO1, regulating inflammatory mediator production in the lipopolysaccharide (LPS)-induced inflammatory response. TDAG51 induction by LPS stimulation was mediated by the TLR2/4 signaling pathway in bone marrow-derived macrophages (BMMs). LPS-induced inflammatory mediator production was significantly decreased in TDAG51-deficient BMMs. In TDAG51-deficient mice, LPS- or pathogenic Escherichia coli infection-induced lethal shock was reduced by decreasing serum proinflammatory cytokine levels. The recruitment of 14-3-3 to FoxO1 was competitively inhibited by the TDAG51-FoxO1 interaction, leading to blockade of FoxO1 cytoplasmic translocation and thereby strengthening FoxO1 nuclear accumulation. TDAG51/FoxO1 double-deficient BMMs showed significantly reduced inflammatory mediator production compared with TDAG51- or FoxO1-deficient BMMs. TDAG51/FoxO1 double deficiency protected mice against LPS- or pathogenic E. coli infection-induced lethal shock by weakening the systemic inflammatory response. Thus, these results indicate that TDAG51 acts as a coactivator of the transcription factor FoxO1, leading to strengthened FoxO1 activity in the LPS-induced inflammatory response.
Project description:As ambush-hunting predators that consume large prey after long intervals of fasting, Burmese pythons evolved with unique adaptations for regulating organ structure and function. Among these is cardiac hypertrophy that develops within three days following a meal (1, 2), which we previously showed was initiated by circulating growth factors (3). Post-prandial cardiac hypertrophy in pythons also rapidly regresses with subsequent fasting (2); however, the molecular mechanisms that regulate the dynamic cardiac remodeling in pythons during digestion are largely unknown. In this study, we employed a multi-omics approach coupled with targeted molecular analyses to examine remodeling of the python ventricular transcriptome and proteome throughout digestion. We found that forkhead box protein O1 (FoxO1) signaling was suppressed prior to hypertrophy development and then activated with regression, which coincided with decreased and then increased expression, respectively, of FoxO1 transcriptional targets involved in protein degradation. To define the molecular mechanistic role of FoxO1 in hypertrophy regression, we used cultured mammalian cardiomyocytes treated with post-fed python plasma. Hypertrophy regression both in pythons and in vitro coincided with activation of FoxO1-dependent autophagy; however, introduction of a FoxO1-specific inhibitor prevented both regression of cell size and autophagy activation. Finally, to determine if FoxO1 activation could induce regression, we generated an adenovirus expressing a constitutively active FoxO1. FoxO1 activation was sufficient to prevent and reverse post-fed plasma-induced hypertrophy, which was partially prevented by autophagy inhibition. Our results indicate that modulation of FoxO1 activity contributes to the dynamic ventricular remodeling in post-prandial Burmese pythons.
Project description:In chicken DT40 cells, there are six linker histone H1 variants and 12 of coding genes. We have previously reported of 11 out of 12 H1 knock out DT40 cells (Takami et al., Genes to Cell 1997 [PMID:9491804]) but complete H1 null DT40 cells could not established, so far. We identified one of the H1 variant, H1R was involved in genomic instabilities (Hashimoto et al., DNA repair (2007) [17613284]), so we re-introduced floxed H1R-eGFP and mer-cre-mer into 11 out of 12 H1 knock out DT40 cells. Then we targeted last enedogenous H1, we successfully established conditional H1 KO cells (K11). Next we treated with tamoxifen to loop out floxed H1R-eGFP, and cloning H1 completely null cells (K11-5, and K11-7). We analysis those gene expression pattern in wild-type, K11, and K11-5 cells Experiment Overall Design: Apoptosis is induced in H1 null cells, so we inhibit apoptosis with pan-caspase inhibitor, Z-VAD-FMK and extract RNAs.
Project description:VEGF induces elongation of endothelial cells (ECs) that are derived from wild-type (Foxo1(+/+)) ES cells. VEGF-induced EC elongation is an important process of angiogenesis. ECs derived from Foxo1(-/-) ES cells fail to elongate in response to VEGF. Gene expression profiling of wild-type and Foxo1(-/-) ECs in the presence or absence of VEGF stimulation identifies responsible genes that regulate EC elongation. One wild-type (Foxo1(+/+)) ES cell clone and one Foxo1(-/-) ES cell clone were used. ES cells were cultured on OP9 stromal cell layer in the presence or absence of VEGF (10 ng/ml). After 6.5 days, VE-cadherin+ CD31+ ECs were isolated by FACS and used for total RNA extraction. Three independent experiments were performed for each condition.
Project description:PAX3-FOXO1 is a fusion transcription factor that is the main driver of tumorigenesis leading to the development of alveolar rhabdomyosarcoma (aRMS). Since aRMS cells are addicted to PAX3-FOXO1 activity, the fusion protein also represents a major target for therapeutic interference, which is however challenging as transcription factors usually cannot be inhibited directly by small molecules. Hence, characterization of the biology of PAX3-FOXO1 might lead to the discovery of new possibilities for an indirect inhibition of its activity. Here, our goal was to characterize the proteomic neighborhood of PAX3-FOXO1 and to find candidates potentially affecting its activity and tumor cell viability. Towards this aim, we expressed BirA fused versions of PAX3-FOXO1 (N- and C-terminal) in HEK293T cells under presence of biotin. In the control setup, we expressed the BirA enzyme alone. After Streptavidin purification of biotinylated proteins, we performed mass spectrometry and quantified relative abundances compared to control conditions. This enabled us to determine PAX3-FOXO1 proximal proteins, which we investigated further in orthogonal endogenous systems.