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Telomeres are protected by shelterin, a six-subunit protein complex that represses the DNA damage response (DDR) at chromosome ends. Extensive data suggest that TRF2 in shelterin remodels telomeres into the t-loop structure, thereby hiding telomere ends from double-stranded break repair and ATM signaling, whereas POT1 represses ATR signaling by excluding RPA. An alternative protection mechanism was suggested recently by which shelterin subunits TRF1, TRF2, and TIN2 mediate telomeric chromatin compaction, which was proposed to minimize access of DDR factors. We performed superresolution imaging of telomeres in mouse cells after conditional deletion of TRF1, TRF2, or both, the latter of which results in the complete loss of shelterin. Upon removal of TRF1 or TRF2, we observed only minor changes in the telomere volume in most of our experiments. Upon codeletion of TRF1 and TRF2, the telomere volume increased by varying amounts, but even those samples exhibiting small changes in telomere volume showed DDR at nearly all telomeres. Upon shelterin removal, telomeres underwent 53BP1-dependent clustering, potentially explaining at least in part the apparent increase in telomere volume. Furthermore, chromatin accessibility, as determined by ATAC-seq (assay for transposase-accessible chromatin [ATAC] with high-throughput sequencing), was not substantially altered by shelterin removal. These results suggest that the DDR induced by shelterin removal does not require substantial telomere decompaction.

Tissue-resident memory T (T-RM) cells persist indefinitely in epithelial barrier tissues and protect the host against pathogens(1-4). However, the biological pathways that enable the long-term survival of T-RM cells are obscure(4,5). Here we show that mouse CD8(+) T-RM cells generated by viral infection of the skin differentially express high levels of several molecules that mediate lipid uptake and intracellular transport, including fatty-acid-binding proteins 4 and 5 (FABP4 and FABP5). We further show that T-cell-specific deficiency of Fabp4 and Fabp5 (Fabp4/Fabp5) impairs exogenous free fatty acid (FFA) uptake by CD8(+) T-RM cells and greatly reduces their long-term survival in vivo, while having no effect on the survival of central memory T (T-CM) cells in lymph nodes. In vitro, CD8(+) T-RM cells, but not CD8(+) T-CM cells, demonstrated increased mitochondrial oxidative metabolism in the presence of exogenous FFAs; this increase was not seen in Fabp4/Fabp5 double-knockout CD8(+) T-RM cells. The persistence of CD8(+) T-RM cells in the skin was strongly diminished by inhibition of mitochondrial FFA beta-oxidation in vivo. Moreover, skin CD8(+) T-RM cells that lacked Fabp4/Fabp5 were less effective at protecting mice from cutaneous viral infection, and lung Fabp4/Fabp5 double-knockout CD8(+) T-RM cells generated by skin vaccinia virus (VACV) infection were less effective at protecting mice from a lethal pulmonary challenge with VACV. Consistent with the mouse data, increased FABP4 and FABP5 expression and enhanced extracellular FFA uptake were also demonstrated in human CD8(+) T-RM cells in normal and psoriatic skin. These results suggest that FABP4 and FABP5 have a critical role in the maintenance, longevity and function of CD8(+) T-RM cells, and suggest that CD8(+) T-RM cells use exogenous FFAs and their oxidative metabolism to persist in tissue and to mediate protective immunity.

Problem Engaging basic scientists in community-based translational research is challenging but has great potential for improving health. Approach In 2009, The Rockefeller University Center for Clinical and Translational Science partnered with Clinical Directors Network, a practice-based research network (PBRN), to create a community-engaged research navigation (CEnR-Nav) program to foster research pairing basic science and community-driven scientific aims. The program is led by an academic navigator and a PBRN navigator. Through meetings and joint activities, the program facilitates basic science-community partnerships and the development and conduct of joint research protocols. Outcomes From 2009-2014, 39 investigators pursued 44 preliminary projects through the CEnR-Nav program; 25 of those became 23 approved protocols and 2 substudies. They involved clinical scholar trainees, early-career physician-scientists, faculty, students, postdoctoral fellows, and others. Nineteen (of 25; 76%) identified community partners, of which 9 (47%) named them as coinvestigators. Nine (of 25; 36%) included T3-T4 translational aims. Seven (of 25; 28%) secured external funding, 11 (of 25; 44%) disseminated results through presentations or publications, and 5 (71%) of 7 projects publishing results included a community partner as a coauthor. Of projects with long-term navigator participation, 9 (of 19; 47%) incorporated T3-T4 aims and 7 (of 19; 37%) secured external funding. Next Steps The CEnR-Nav program provides a model for successfully engaging basic scientists with communities to advance and accelerate translational science. This model's durability and generalizability have not been determined, but it achieves valuable short-term goals and facilitates scientifically meaningful community-academic partnerships.

Cancer cells are characterized by aberrant epigenetic landscapes and often exploit chromatin machinery to activate oncogenic gene expression programs(1). Recognition of modified histones by 'reader' proteins constitutes a key mechanism underlying these processes; therefore, targeting such pathways holds clinical promise, as exemplified by the development of bromodomain and extra-terminal (BET) inhibitors(2,3). We recently identified the YEATS domain as an acetyl-lysine-binding module(4), but its functional importance in human cancer remains unknown. Here we show that the YEATS domain-containing protein ENL, but not its paralogue AF9, is required for disease maintenance in acute myeloid leukaemia. CRISPR-Cas9-mediated depletion of ENL led to anti-leukaemic effects, including increased terminal myeloid differentiation and suppression of leukaemia growth in vitro and in vivo. Biochemical and crystal structural studies and chromatin-immunoprecipitation followed by sequencing analyses revealed that ENL binds to acetylated histone H3, and co-localizes with H3K27ac and H3K9ac on the promoters of actively transcribed genes that are essential for leukaemia. Disrupting the interaction between the YEATS domain and histone acetylation via structure-based mutagenesis reduced the recruitment of RNA polymerase II to ENL-target genes, leading to the suppression of oncogenic gene expression programs. Notably, disrupting the functionality of ENL further sensitized leukaemia cells to BET inhibitors. Together, our data identify ENL as a histone acetylation reader that regulates oncogenic transcriptional programs in acute myeloid leukaemia, and suggest that displacement of ENL from chromatin may be a promising epigenetic therapy, alone or in combination with BET inhibitors, for aggressive leukaemia.

Replicative helicases are ring-shaped hexamers that encircle DNA for duplex unwinding. The currently accepted view of hexameric helicase function is by steric exclusion, where the helicase encircles one DNA strand and excludes the other, acting as a wedge with an external DNA unwinding point during translocation. Accordingly, strand-specific blocks only affect these helicases when placed on the tracking strand, not the excluded strand. We examined the effect of blocks on the eukaryotic CMG and, contrary to expectations, blocks on either strand inhibit CMG unwinding. A recent cryoEM structure of yeast CMG shows that duplex DNA enters the helicase and unwinding occurs in the central channel. The results of this report inform important aspects of the structure, and we propose that CMG functions by a modified steric exclusion process in which both strands enter the helicase and the duplex unwinding point is internal, followed by exclusion of the non-tracking strand.

Neuroscience is entering a collaborative era in which powerful new technologies, generated by large scientific projects in many countries, will have a dramatic impact on science, medicine, and society. Coordinating these international initiatives and ensuring broad distribution of novel technologies and open accessibility of the generated data will multiply their value, while tapping creativity and expertise from every source.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP- binding cassette (ABC) transporter that uniquely functions as an ion channel. Here, we present a 3.9 angstrom structure of dephosphorylated human CFTR without nucleotides, determined by electron cryomicroscopy (cryo- EM). Close resemblance of this human CFTR structure to zebrafish CFTR under identical conditions reinforces its relevance for understanding CFTR function. The human CFTR structure reveals a previously unresolved helix belonging to the R domain docked inside the intracellular vestibule, precluding channel opening. By analyzing the sigmoid time course of CFTR current activation, we propose that PKA phosphorylation of the R domain is enabled by its infrequent spontaneous disengagement, which also explains residual ATPase and gating activity of dephosphorylated CFTR. Fromcomparison with MRP1, a feature distinguishing CFTR from all other ABC transporters is the helix- loop transition in transmembrane helix 8, which likely forms the structural basis for CFTR's channel function.

Innate lymphoid cells (ILCs) represent innate versions of T helper and cytotoxic T cells that differentiate from committed ILC precursors (ILCPs). How ILCPs give rise to mature tissue-resident ILCs remains unclear. Here, we identify circulating and tissue ILCPs in humans that fail to express the transcription factors and cytokine outputs of mature ILCs but have these signature loci in an epigenetically poised configuration. Human ILCPs robustly generate all ILC subsets in vitro and in vivo. While human ILCPs express low levels of retinoic acid receptor (RAR)-related orphan receptor C (RORC) transcripts, these cells are found in RORC-deficient patients and retain potential forEOMES(+) natural killer (NK) cells, interferon gamma-positive (IFN-gamma(+)) ILC1s, interleukin (IL)-13(+) ILC2s, and for IL-22(+), but not for IL-17A(+) ILC3s. Our results support a model of tissue ILC differentiation ("ILC-poiesis''), whereby diverse ILC subsets are generated in situ from systemically distributed ILCPs in response to local environmental signals.

Oil palm is the most productive oil crop in the world and composes 36% of the world production. However, the molecular mechanisms of hybrids vigor (or heterosis) between Dura, Pisifera and their hybrid progeny Tenera has not yet been well understood. Here we compared the temporal and spatial compositions of lipids and transcriptomes for two oil yielding organs mesocarp and endosperm from Dura, Pisifera and Tenera. Multiple lipid biosynthesis pathways are highly enriched in all non-additive expression pattern in endosperm, while cytokinine biosynthesis and cell cycle pathways are highly enriched both in endosperm and mesocarp. Compared with parental palms, the high oil content in Tenera was associated with much higher transcript levels of EgWRI1, homolog of Arabidopsis thaliana WRINKLED1. Among 338 identified genes in lipid synthesis, 207 (61%) has been identified to contain the WRI1 specific binding AW motif. We further functionally identified EgWRI1-1, one of three EgWRI1 orthologs, by genetic complementation of the Arabidopsis wri1 mutant. Ectopic expression of EgWRI1-1 in plant produced dramatically increased seed mass and oil content, with oil profile changed. Our findings provide an explanation for EgWRI1 as an important gene contributing hybrid vigor in lipid biosynthesis in oil palm.