Mouse embryonic stem cells (ESCs) sporadically transit into an early embryonic-like state characterized by the expression of 2-cell (2C) stage-restricted transcripts. Here, we identify a maternal ...factor-negative elongation factor A (NELFA)-whose heterogeneous expression in mouse ESCs is coupled to 2C gene upregulation and expanded developmental potential in vivo. We show that NELFA partners with Top2a in an interaction specific to the 2C-like state, and that it drives the expression of Dux-a key 2C regulator. Accordingly, loss of NELFA and/or Top2a suppressed Dux activation. Further characterization of 2C-like cells uncovered reduced glycolytic activity; remarkably, mere chemical suppression of glycolysis was sufficient to promote a 2C-like fate, obviating the need for genetic manipulation. Global chromatin state analysis on NELFA-induced cells revealed decommissioning of ESC-specific enhancers, suggesting ESC-state impediments to 2C reversion. Our study positions NELFA as one of the earliest drivers of the 2C-like state and illuminates factors and processes that govern this transition.
Retroviral reverse transcriptase (RT) of Moloney murine leukemia virus (MoMLV) is expressed in the form of a large Gag-Pol precursor protein by suppression of translational termination in which the ...maximal efficiency of stop codon read-through depends on the interaction between MoMLV RT and peptidyl release factor 1 (eRF1). Here, we report the crystal structure of MoMLV RT in complex with eRF1. The MoMLV RT interacts with the C-terminal domain of eRF1 via its RNase H domain to sterically occlude the binding of peptidyl release factor 3 (eRF3) to eRF1. Promotion of read-through by MoMLV RNase H prevents nonsense-mediated mRNA decay (NMD) of mRNAs. Comparison of our structure with that of HIV RT explains why HIV RT cannot interact with eRF1. Our results provide a mechanistic view of how MoMLV manipulates the host translation termination machinery for the synthesis of its own proteins.
Cancer cells undergo transcriptional reprogramming to drive tumor progression and metastasis. Using cancer cell lines and patient-derived tumor organoids, we demonstrate that loss of the negative ...elongation factor (NELF) complex inhibits breast cancer development through downregulating epithelial-mesenchymal transition (EMT) and stemness-associated genes. Quantitative multiplexed Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins (qPLEX-RIME) further reveals a significant rewiring of NELF-E-associated chromatin partners as a function of EMT and a co-option of NELF-E with the key EMT transcription factor SLUG. Accordingly, loss of NELF-E leads to impaired SLUG binding on chromatin. Through integrative transcriptomic and genomic analyses, we identify the histone acetyltransferase, KAT2B, as a key functional target of NELF-E-SLUG. Genetic and pharmacological inactivation of KAT2B ameliorate the expression of EMT markers, phenocopying NELF ablation. Elevated expression of NELF-E and KAT2B is associated with poorer prognosis in breast cancer patients, highlighting the clinical relevance of our findings. Taken together, we uncover a crucial role of the NELF-E-SLUG-KAT2B epigenetic axis in breast cancer carcinogenesis.
Abstract Soft tissue sarcomas (STS) are a highly heterogeneous collection of tumors that arise from primitive mesenchymal cells. Due to a reliance on cytotoxic chemotherapy as standard of care, ...survival outcomes for advanced STS patients remain poor. While efforts to understand sarcomagenesis have revealed potential biomarkers, the diversity of STS subtypes and interpatient tumour heterogeneity has led to the lack of effective molecular targeted therapies available. Given the uniquely individualized nature of STS, we hypothesize that the application of an experimental-analytics method, Quadratic Phenotypic Optimization Platform (QPOP), towards primary STS patient samples can improve identification of patient-specific drug combinations. Across a total of 45 patient samples collected, QPOP identified a novel drug pair as most frequently top-ranked, outperforming standard of care ifosfamide and doxorubicin. Interestingly, analysis of QPOP ranking trends revealed this combination to be broadly effective, implying common targetable pathways independent of STS subtype. Single-drug and combination dose-response assays performed in a panel of established patient lines supported its synergistic interaction, accompanied by increased PARP and caspase-3 cleavage with immunoblotting, and increased apoptotic response with Annexin V assay. Mechanistically, this synergy results in cell cycle arrest and induction of programmed cell death pathways, as revealed by molecular profiling on representative patient and cell lines. We further showed that co-treatment synergistically repressed oncogenic MYC and activated the p27kip1 tumor suppressor. Finally, this combination was more effective at impairing tumor progression than single agents alone in an STS xenograft mouse model. Overall, work here provides preliminary clinical evidence for the prioritization of a novel drug pair in addressing STS beyond known clinicopathologic parameters. Citation Format: Sharon Pei Yi Chan, Wai Yee Wong, Nur Nadiah Ismail, Baiwen Luo, Benjamin Jieming Chen, Brandon Xuan Ming Phua, Xing Yi Woo, Tan Boon Toh, Edward Kai-Hua Chow, Valerie Shiwen Yang. Ex vivo Drug Testing Identifies a Novel Drug Pair in Targeting STS abstract. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P41.
Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to ...overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative efforts, scientific breakthroughs can be made sooner and capitalized for the betterment of humanity.
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