Cellular stresses initiate well-coordinated signaling response pathways. As the proper regulation of stress is essential for cellular homeostasis, the defects of stress response pathways result in ...functional deficits and cell death. Although mitochondrial SIRT4 has been shown to be involved in cellular stress response and tumor suppression, its roles in survival and drug resistance of cancer cells are not well determined. Here we show that SIRT4 is a crucial regulator of the stress resistance of cancer cells. SIRT4 is highly induced by various cellular stresses and contributes to cell survival and growth after stresses. SIRT4 loss sensitizes cells to DNA damage or ER stress. Moreover, SIRT4 induction is required for tumorigenic transformation, as SIRT4 null cells are vulnerable to oncogene activation. Thus, these results suggest that SIRT4 has essential roles in stress resistance and may be an important therapeutic target for cancer treatment.
•SIRT4 is induced by oncogenic stresses such as DNA damage, ER stress and oncogene activation.•SIRT4 is a crucial regulator of the stress resistance of cancer cells.•SIRT4 supports cell survival during oncogene-induced transformation.
The transferrin receptor (TfR1) is upregulated in malignant cells and its expression is associated with cancer progression. Because of its pre-eminent role in cell proliferation, TfR1 has been an ...important target for the development of cancer therapy. Although TfR1 is highly expressed in pancreatic cancers, what it carries out in these refractory cancers remains poorly understood. Here we report that TfR1 supports mitochondrial respiration and ROS production in human pancreatic ductal adenocarcinoma (PDAC) cells, which is required for their tumorigenic growth. Elevated TfR1 expression in PDAC cells contributes to oxidative phosphorylation, which allows for the generation of ROS. Importantly, mitochondrial-derived ROS are essential for PDAC growth. However, exogenous iron supplement cannot rescue the defects caused by TfR1 knockdown. Moreover, we found that TfR1 expression determines PDAC cells sensitivity to oxidative stress. Together, our findings reveal that TfR1 can contribute to the mitochondrial respiration and ROS production, which have essential roles in growth and survival of pancreatic cancer.
•Pancreatic ductal adenocarcinoma (PDAC) exhibits an elevated transferrin receptor (TfR1) expression in comparison with non-transformed pancreatic cells.•TfR1 is required for PDAC growth by regulating mitochondrial respiration and ROS production.•TfR1 functions as a determinant of cell viability to oxidative stress in PDAC cells.
Graded Sonic hedgehog (Shh) signaling governs vertebrate limb skeletal patterning along the anteroposterior (AP) axis by regulating the activity of bifunctional Gli transcriptional regulators. The ...genetic networks involved in this patterning are well defined, however, the epigenetic control of the process by chromatin remodelers remains unknown. Here, we report that the SWI/SNF chromatin remodeling complex is essential for Shh-driven limb AP patterning. Specific inactivation of Srg3/mBaf155, a core subunit of the remodeling complex, in developing limb buds hampered the transcriptional upregulation of Shh/Gli target genes, including the Shh receptor Ptch1 and its downstream effector Gli1 in the posterior limb bud. In addition, Srg3 deficiency induced ectopic activation of the Hedgehog (Hh) pathway in the anterior mesenchyme, resulting in loss of progressive asymmetry. These defects in the Hh pathway accompanied aberrant BMP activity and disruption of chondrogenic differentiation in zeugopod and autopod primordia. Notably, our data revealed that dual control of the Hh pathway by the SWI/SNF complex is essential for spatiotemporal transcriptional regulation of the BMP antagonist Gremlin1, which affects the onset of chondrogenesis. This study uncovers the bifunctional role of the SWI/SNF complex in the Hh pathway to determine the fate of AP skeletal progenitors.
During exercise, skeletal muscle is exposed to a low oxygen condition, hypoxia. Under hypoxia, the transcription factor hypoxia-inducible factor-1α (HIF-1α) is stabilized and induces expressions of ...its target genes regulating glycolytic metabolism. Here, using a skeletal muscle-specific gene ablation mouse model, we show that Brg1/Brm-associated factor 155 (Baf155), a core subunit of the switch/sucrose non-fermentable (SWI/SNF) complex, is essential for HIF-1α signaling in skeletal muscle. Muscle-specific ablation of Baf155 increases oxidative metabolism by reducing HIF-1α function, which accompanies the decreased lactate production during exercise. Furthermore, the augmented oxidation leads to high intramuscular adenosine triphosphate (ATP) level and results in the enhancement of endurance exercise capacity. Mechanistically, our chromatin immunoprecipitation (ChIP) analysis reveals that Baf155 modulates DNA-binding activity of HIF-1α to the promoters of its target genes. In addition, for this regulatory function, Baf155 requires a phospho-signal transducer and activator of transcription 3 (pSTAT3), which forms a coactivator complex with HIF-1α, to activate HIF-1α signaling. Our findings reveal the crucial role of Baf155 in energy metabolism of skeletal muscle and the interaction between Baf155 and hypoxia signaling.
T cell‐mediated antitumor immunity is modulated, in part, by N‐glycosylation. However, the interplay between N‐glycosylation and the loss of effector function in exhausted T cells has not yet been ...fully investigated. Here, we delineated the impact of N‐glycosylation on the exhaustion of tumor‐infiltrating lymphocytes in a murine colon adenocarcinoma model, focusing on the IFN‐γ‐mediated immune response. We found that exhausted CD8+ T cells downregulated the oligosaccharyltransferase complex, which is indispensable for N‐glycan transfer. Concordant N‐glycosylation deficiency in tumor‐infiltrating lymphocytes leads to loss of antitumor immunity. Complementing the oligosaccharyltransferase complex restored IFN‐γ production and alleviated CD8+ T cell exhaustion, resulting in reduced tumor growth. Thus, aberrant glycosylation induced in the tumor microenvironment incapacitates effector CD8+ T cells. Our findings provide insights into CD8+ T cell exhaustion by incorporating N‐glycosylation to understand the characteristic loss of IFN‐γ, opening new opportunities to amend the glycosylation status in cancer immunotherapies.
In this study, we investigated how defective N‐glycosylation contributes to the exhaustion of tumor‐infiltrating CD8+ T cells by impairing IFN‐γ‐mediated effector function. Downregulation of the oligosaccharyltransferase (OST) complex and the concordant loss of fully‐N‐glycosylated IFN‐γ were observed in exhausted CD8+ T cells. We further report that complementing the OST complex augmented IFN‐γ production and enhanced antitumor immunity.
The advent of the assay for transposase-accessible chromatin using sequencing (ATAC-seq) has shown great potential as a leading method for analyzing the genome-wide profiling of chromatin ...accessibility. A comprehensive reference to the ATAC-seq dataset for disease progression is important for understanding the regulatory specificity caused by genetic or epigenetic changes. In this study, we present a genome-wide chromatin accessibility profile of 44 liver samples spanning the full histological spectrum of nonalcoholic fatty liver disease (NAFLD). We analyzed the ATAC-seq signal enrichment, fragment size distribution, and correlation coefficients according to the histological severity of NAFLD (healthy control vs steatosis vs fibrotic nonalcoholic steatohepatitis), demonstrating the high quality of the dataset. Consequently, 112,303 merged regions (genomic regions containing one or multiple overlapping peak regions) were identified. Additionally, we found differentially accessible regions (DARs) and performed transcription factor binding motif enrichment analysis and
motif analysis to determine new biomarker candidates. These data revealed the generegulatory interactions and noncoding factors that can affect NAFLD progression. In summary, our study provides a valuable resource for the human epigenome by applying an advanced approach to facilitate diagnosis and treatment by understanding the non-coding genome of NAFLD.
Dermal fibroblasts lose stem cell potency after birth, which prevents regenerative healing. However, the underlying intracellular mechanisms are largely unknown. We uncover the postnatal maturation ...of papillary fibroblasts (PFs) driven by the extensive Twist2-mediated remodeling of chromatin accessibility. A loss of the regenerative ability of postnatal PFs occurs with decreased H3K27ac levels. Single-cell transcriptomics, assay for transposase-accessible chromatin sequencing (ATAC-seq), and chromatin immunoprecipitation sequencing (ChIP-seq) reveal the postnatal maturation trajectory associated with the loss of the regenerative trajectory in PFs, which is characterized by a marked decrease in chromatin accessibility and H3K27ac modifications. Histone deacetylase inhibition delays spontaneous chromatin remodeling, thus maintaining the regenerative ability of postnatal PFs. Genomic analysis identifies Twist2 as a major regulator within chromatin regions with decreased accessibility during the postnatal period. When Twist2 is genetically deleted in dermal fibroblasts, the intracellular cascade of postnatal maturation is significantly delayed. Our findings reveal the comprehensive intracellular mechanisms underlying intrinsic postnatal changes in dermal fibroblasts.
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•Postnatal papillary fibroblasts lose regenerative ability when H3K27ac levels decrease•Chromatin accessibility is decreased along with H3K27ac levels in postnatal fibroblasts•HDAC inhibition delays postnatal chromatin remodeling, which prevents WNT inactivation•Twist2 deletion in fibroblasts is sufficient to delay the postnatal maturation process
Kim et al. show that postnatal papillary fibroblasts lose regenerative ability when H3K27ac levels decrease. Chromatin accessibility is decreased along with H3K27ac modifications. HDAC inhibition delays chromatin remodeling, which prevents postnatal WNT inactivation. Genetic deletion of Twist2 in fibroblasts is sufficient to delay the postnatal maturation process.
Although SWI3-related gene (SRG3), a chromatin remodeling factor, is critical for various biological processes including early embryogenesis and thymocyte development, it is unclear whether SRG3 is ...involved in the differentiation of CD4+ T cells, the key mediator of adaptive immune responses. Because it is known that experimental autoimmune encephalomyelitis (EAE) development is determined by the activation of CD4+ T helper cells, here, we investigated the role of SRG3 in EAE development using SRG3 transgenic mouse models exhibiting two distinct SRG3 expression patterns: SRG3 expression driven by either the CD2 or β-actin promoter. We found that the outcome of EAE development was completely different depending on the expression pattern of SRG3. The specific over-expression of SRG3 using the CD2 promoter facilitated EAE via the induction of Th1 and Th17 cells, whereas the ubiquitous over-expression of SRG3 using the β-actin promoter inhibited EAE by promoting Th2 differentiation and suppressing Th1 and Th17 differentiation. In addition, the ubiquitous over-expression of SRG3 polarized CD4+ T cell differentiation towards the Th2 phenotype by converting dendritic cells (DCs) or macrophages to Th2 types. SRG3 over-expression not only reduced pro-inflammatory cytokine production by DCs but also shifted macrophages from the inducible nitric oxide synthase (iNOS)-expressing M1 phenotype to the arginase-1-expressing M2 phenotype during EAE. In addition, Th2 differentiation in β-actin-SRG3 Tg mice during EAE was associated with an increase in the basophil and mast cell populations and in IL4 production. Furthermore, the increased frequency of Treg cells in the spinal cord of β-actin-SRG3 Tg mice might induce the suppression of and accelerate the recovery from EAE symptoms. Taken together, our results provide the first evidence supporting the development of a new therapeutic strategy for EAE involving the modulation of SRG3 expression to induce M2 and Th2 polarization, thereby inhibiting inflammatory immune responses.
Human SNF5 and BAF155 constitute the core subunit of multi-protein SWI/SNF chromatin-remodeling complexes that are required for ATP-dependent nucleosome mobility and transcriptional control. Human ...SNF5 (hSNF5) utilizes its repeat 1 (RPT1) domain to associate with the SWIRM domain of BAF155. Here, we employed X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and various biophysical methods in order to investigate the detailed binding mechanism between hSNF5 and BAF155. Multi-angle light scattering data clearly indicate that hSNF5
and BAF155
are both monomeric in solution and they form a heterodimer. NMR data and crystal structure of the hSNF5
/BAF155
complex further reveal a unique binding interface, which involves a coil-to-helix transition upon protein binding. The newly formed α
helix of hSNF5
interacts with the β2-α1 loop of hSNF5 via hydrogen bonds and it also displays a hydrophobic interaction with BAF155
. Therefore, the
-terminal region of hSNF5
plays an important role in tumorigenesis and our data will provide a structural clue for the pathogenesis of Rhabdoid tumors and malignant melanomas that originate from mutations in the
-terminal loop region of hSNF5.
Semiconductors processed at low temperature for complementary metal-oxide semiconductors (CMOS) devices are receiving considerable attention in the field of integrated electronic applications. In ...this work, we demonstrated a CMOS inverter constructed by n-type ZnON and p-type Te TFTs where all the processes have been done at low temperature. The electrical measurements of proposed TFTs exhibit high mobility (> 100 and > 3 cm
2
/Vs in case of ZnON and Te TFTs, respectively) and a stable on/off current ratio. The resulted CMOS inverter exhibits a high voltage swing and a high voltage gain of 15.89. Since all the synthesis and fabrication processes are performed at low temperatures with easy processing techniques, the results may open new opportunities in the field of integrated electronics field.
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