Human cancer genome sequencing has recently revealed that genes encoding subunits of SWI/SNF chromatin remodeling complexes are frequently mutated across a wide variety of cancers, and several subunits of the complex have been shown to have bona fide tumor suppressor activity1. However, whether mutations in SWI/SNF subunits result in shared dependencies is unknown. Here we show that EZH2, a catalytic subunit of the Polycomb repressive complex 2 (PRC2), is essential in all tested cancer cell lines and xenografts harboring mutations of the SWI/SNF subunits ARID1A, PBRM1, and SMARCA4, which are several of the most frequently mutated SWI/SNF subunits in human cancer but that co–occurrence of a Ras pathway mutation correlates with abrogation of this dependence. Surprisingly, we demonstrate that SWI/SNF mutant cancer cells are primarily dependent upon a non–catalytic role of EZH2 in stabilization of the PRC2 complex, and only partially dependent on EZH2 histone methyltransferase activity. These results not only reveal a shared dependency of cancers with genetic alterations in SWI/SNF subunits, but also suggest that EZH2 enzymatic inhibitors now in clinical development may not fully suppress the oncogenic activity of EZH2.

A notably higher prevalence of dementia and AD was found in rural areas than in urban ones, and education might be an important reason for the urban-rural differences.

Genes encoding subunits of SWI/SNF (BAF) chromatin remodelling complexes are collectively altered in over 20% of human malignancies, but the mechanisms by which these complexes alter chromatin to modulate transcription and cell fate are poorly understood. Utilizing mouse embryonic fibroblast and cancer cell line models, here we show via ChIP-seq and biochemical assays that SWI/SNF complexes are preferentially targeted to distal lineage specific enhancers and interact with p300 to modulate histone H3 lysine 27 acetylation. We identify a greater requirement for SWI/SNF at typical enhancers than at most super-enhancers and at enhancers in untranscribed regions than in transcribed regions. Our data further demonstrate that SWI/SNF-dependent distal enhancers are essential for controlling expression of genes linked to developmental processes. Our findings thus establish SWI/SNF complexes as regulators of the enhancer landscape and provide insight into the roles of SWI/SNF in cellular fate control.

Well-characterized promoters are essential tools for metabolic engineering and synthetic biology. In Streptomyces coelicolor, the native kasOp is a temporally expressed promoter strictly controlled by two regulators, ScbR and ScbR2. In this work, first, kasOp was engineered to remove a common binding site of ScbR and ScbR2 upstream of its core region, thus generating a stronger promoter, kasOp 3 . Second, another ScbR binding site internal to the kasOp 3 core promoter region was abolished by random mutation and screening of the mutant library to obtain the strongest promoter, kasOp* (where the asterisk is used to distinguish the engineered promoter from the native promoter). The activities of kasOp* were compared with those of two known strong promoters, ermEp* and SF14p, in three Streptomyces species. kasOp* showed the highest activity at the transcription and protein levels in all three hosts. Furthermore, relative to ermEp* and SF14p, kasOp* was shown to confer the highest actinorhodin production level when used to drive the expression of actII-ORF4 in S. coelicolor. Therefore, kasOp* is a simple and well-defined strong promoter useful for gene overexpression in streptomycetes.

No abstract

Besides genome editing, CRISPR-Cas12a has recently been used for DNA detection applications with attomolar sensitivity but, to our knowledge, it has not been used for the detection of small molecules. Bacterial allosteric transcription factors (aTFs) have evolved to sense and respond sensitively to a variety of small molecules to benefit bacterial survival. By combining the single-stranded DNA cleavage ability of CRISPR-Cas12a and the competitive binding activities of aTFs for small molecules and double-stranded DNA, here we develop a simple, supersensitive, fast and high-throughput platform for the detection of small molecules, designated CaT-SMelor ( C RISPR-Cas12a- and aT F-mediated s mall m ol e cu l e detect or ). CaT-SMelor is successfully evaluated by detecting nanomolar levels of various small molecules, including uric acid and p -hydroxybenzoic acid among their structurally similar analogues. We also demonstrate that our CaT-SMelor directly measured the uric acid concentration in clinical human blood samples, indicating a great potential of CaT-SMelor in the detection of small molecules.

Upon secretion, transforming growth factor (TGF) β is maintained in a sequestered state in extracellular matrix as a latent form. The latent TGFβ is considered as a molecular sensor that releases active TGFβ in response to the perturbations of the extracellular matrix at the situations of mechanical stress, wound repair, tissue injury, and inflammation. The biological implication of the temporal discontinuity of TGFβ storage in the matrix and its activation is obscure. Here, using several animal models in which latent TGFβ is activated in vascular matrix in response to injury of arteries, we show that active TGFβ controls the mobilization and recruitment of (messenchymal stem cells) MSCs to participate in tissue repair and remodeling. MSCs were mobilized into the peripheral blood in response to vascular injury and recruited to the injured sites where they gave rise to both endothelial cells for reendothelialization and myofibroblastic cells to form thick neointima. TGFβ were activated in the vascular matrix in both rat and mouse models of mechanical injury of arteries. Importantly, the active TGFβ released from the injured vessels is essential to induce the migration of MSCs, and cascade expression of monocyte chemotactic protein-1 (MCP-1) stimulated by TGFβ amplifies the signal for migration. Moreover, sustained high levels of active TGFβ were observed in peripheral blood, and at the same time points following injury, Sca1+CD29+CD11b−CD45− MSCs, in which 91% are nestin+ cells, were mobilized to peripheral blood and recruited to the remodeling arteries. Intravenously injection of recombinant active TGFβ1 in uninjured mice rapidly mobilized MSCs into circulation. Further, inhibitor of TGFβ type I receptor (TβRI) blocked the mobilization and recruitment of MSCs to the injured arteries. Thus, TGFβ is an injury-activated messenger essential for the mobilization and recruitment of MSCs to participate in tissue repair/remodeling.

Recent studies have shown that cerebellar Bergmann glia display coordinated Ca 2+ transients in live mice. However, the functional significance of Bergmann glial Ca 2+ signaling remains poorly understood. Using transgenic mice that allow selective stimulation of glial cells, we report here that cytosolic Ca 2+ regulates uptake of K + by Bergmann glia, thus providing a powerful mechanism for control of Purkinje cell-membrane potential. The decline in extracellular K + evoked by agonist-induced Ca 2+ in Bergmann glia transiently increased spike activity of Purkinje cells in cerebellar slices as well as in live anesthetized mice. Thus, Bergmann glia play a previously unappreciated role in controlling the membrane potential and thereby the activity of adjacent Purkinje cells.two-photon laser scanning microscopy | ion-sensitive microelectrode B ergmann glial cells in cerebellum are electrically nonexcitable cells that in many ways serve the same functions as protoplasmic astrocytes in forebrain. Bergmann glia are chiefly responsible for glutamate uptake and extracellular K + homeostasis (1). Their highly negative resting membrane potential of −80 to −85 mV combined with a large number of inwardly rectifying K + channels helps maintain a tight control of extracellular K + concentration (2). Bergmann glial cells also display Ca 2+ transients in response to glutamate or stimulation of climbing and parallel fibers in slices and to motor activity in vivo (3). However, although glial Ca 2+ signaling has been shown to regulate synaptic transmission in several brain regions, it is presently not established whether Bergmann glia can modulate the activity of Purkinje cells.Membrane potentials of almost all neurons in mammalian brain fluctuate between a hyperpolarized state (down state) and depolarized state (up state) during sleep/anesthesia and quiet wakefulness (4, 5). These fluctuations of the membrane potentials are synchronized between neighboring cells and detected as slow (∼0.5-1 Hz), large-amplitude delta waves (4). Even though the existence of bistability of Purkinje cells in awake mice has been questioned, it is generally agreed that bistability is a common phenomenon in both anesthetized and sleeping animals (5). The bistability of the resting membrane potential in Purkinje cells was first discovered by Llinás and Sugimori in cerebellar slices (6, 7). The current model predicts that bistability of Purkinje cells, similar to thalamic neurons, relies on the balance between noninactivating inward currents (persistent Na + currents and/or T-type Ca 2+ currents) (4, 8, 9) and an outward K + leak current (5-7, 10). However, Purkinje cell bistability is not simply an expression of intrinsic membrane properties because complex spikes generated by climbing fiber activation can toggle the membrane potential between up and down states in vivo (5). Recently, glutamate uncaging on distal dendrites of striate spiny neurons was shown to induce up states that lasted hundreds of milliseconds (11), and small hyperpolarization current...