Transition metal catalysis serves as a fundamental strategy for transforming inert C-H bonds into valuable functional motifs. However, achieving regioselective activation of remote C-H bonds remains challenging, particul...Transition metal catalysis serves as a fundamental strategy for transforming inert C-H bonds into valuable functional motifs. However, achieving regioselective activation of remote C-H bonds remains challenging, particularly in unbiased hydrocarbon frameworks. In this context, distal C(sp)-H bonds are especially difficult to functionalize, as conformational flexibility favors proximal C-H activation. In this study, we demonstrate a ligand-enabled strategy using designed O-allyl amido ester (OAAE) ligands for palladium-catalyzed activation of γ-methylene and methine C-H sites in unbiased aliphatic carboxylic acids, derived from readily available fatty and cyclic acid feedstocks. This protocol enables direct transformation of aliphatic carboxylic acid substrates into distal desaturated γ-lactones and double dehydrogenated γ-spirolactones. Mechanistic studies are consistent with a pathway involving Pd(II)-mediated γ-C(sp)-H activation, followed by dehydrogenation and intramolecular cyclization. These lactones with an unsaturated arm, serve as key intermediates for the formation of complex natural products and pharmaceuticals. For instance, muricatacin (from soursop/laxman phal) and its analogue were rapidly assembled in three steps from margaric acid using this strategy and evaluated for anticancer activity, thereby demonstrating the potential of our approach for providing a rapid access to biologically relevant frameworks for traditional medicine. The introduced distal desaturation further opens up new avenues for remote functionalization, streamlining access to diverse bioactive molecules with improved step and atom economy.
Bower OJ, R Orsi AE, McMahon R
… +22 more, Staneva D, Blagrove J, Singh K, Simon CS, McCarthy A, Garcia P, Shaikly V, Taranissi M, Wilding M, Serhal P, Odia RA, Vasilic M, Choudhary M, Papathanasiou A, Elder K, Snell P, Christie L, Arbab M, Liu DR, Herbert M, Harasimov K, Niakan KK
Understanding how the first cell lineages in human development are specified and maintained has fundamental importance and clinical implications for regenerative medicine, infertility and pregnancy loss. While mouse mode...Understanding how the first cell lineages in human development are specified and maintained has fundamental importance and clinical implications for regenerative medicine, infertility and pregnancy loss. While mouse models have provided valuable insights into transcription factors regulating early development, translating these findings to human embryos has been limited by ethical, technical and biological constraints. Functional studies of transcription factors in human embryos have been hindered by nuclease-based genome-editing approaches that induce genotoxicity. To overcome this, we applied adenine base editing (ABE8e) to precisely target an exon splice donor site, resulting in a splicing defect and functional knockout of NANOG, representing the first application of base editing to study a developmental regulator in human embryos. This approach did not trigger genotoxicity and showed limited off-target editing. Loss of NANOG disrupts pluripotent epiblast specification and instead cells differentiate toward a primitive endoderm (yolk sac) or trophectoderm (placental) transcriptional programme. Retention of primitive endoderm differentiation in NANOG-edited human embryos reveals a functional compensation distinct from mouse, underscoring the importance of directly investigating human development. Our findings demonstrate an essential role for NANOG in human pluripotency and epiblast specification, and highlight the utility of base editing for functional interrogation of human development.
Guo A, Huang H, Zhu Z
… +19 more, Chen MJ, Shi H, Yuan S, Sharma P, Connelly JP, Liedmann S, Dhungana Y, Li Z, Haydar D, Yang M, Beere H, Yustein JT, DeRenzo C, Pruett-Miller SM, Crawford JC, Krenciute G, Roberts CWM, Chi H, Green DR
Metabolism of the hepatic low-density lipoprotein receptor (LDLR) is a key determinant of cholesterol homeostasis. The molecular switches that coordinate LDLR trafficking and turnover in response to nutritional cues, inc...Metabolism of the hepatic low-density lipoprotein receptor (LDLR) is a key determinant of cholesterol homeostasis. The molecular switches that coordinate LDLR trafficking and turnover in response to nutritional cues, including high dietary cholesterol, remain poorly defined. Here we identify a new pathway regulated by Ral GTPases that links extracellular cholesterol signals to the intracellular trafficking machinery controlling LDLR turnover. Chronic dietary cholesterol activates the Ral proteins by increasing RAS activity, routing LDLR to lysosomes for degradation and inhibiting its recycling independently of transcriptional regulation or PCSK9. Constitutive activation of Ral via RalGAPB deletion or overexpression of constitutively active Ral mutants in hepatocytes reduces LDLR levels and impairs cholesterol clearance. Ral engages the endocytic RalBP1-REPS1 complex to promote LDLR internalization and lysosomal routing, where LDLR is degraded by the lysosomal protease cathepsin A (CTSA). Ral activation directs CTSA towards lysosomes for maturation while limiting its secretion, further promoting LDLR degradation in lysosomes. Genetic variants in this pathway significantly associate with altered cholesterol in humans. Pharmacological inhibition of CTSA activity increases hepatic LDLR function and improves cholesterol clearance, offering a potential new therapeutic strategy for hypercholesterolaemia and cardiovascular disease.
Sudden cardiac death is, in theory, preventable with defibrillators. But every year, many patients die without defibrillators because doctors fail to predict their risk. The only predictive biomarker in wide use, cardiac...Sudden cardiac death is, in theory, preventable with defibrillators. But every year, many patients die without defibrillators because doctors fail to predict their risk. The only predictive biomarker in wide use, cardiac left ventricular ejection fraction (LVEF), misses most sudden cardiac deaths, and flags many low-risk patients for futile defibrillators that never fire. Here we apply deep learning to a dataset linking all electrocardiograms (ECGs) in a Swedish region to death certificates. The resulting model isolates a high-risk group (2.2% of the sample) with a 7.0% annual rate of sudden cardiac death, higher than those with reduced LVEF (1.9% of the sample; 4.6% annual rate). Notably, 86.1% of the model's high-risk patients were not flagged by LVEF. High-risk ECG patients with defibrillators implanted were 54.4% less likely to die than expected, suggesting a mortality benefit. We externally validate the model in a US health system, in which it predicts ventricular arrhythmias that cause sudden death; and a Taiwanese hospital registry, in which it specifically predicts future arrhythmic cardiac arrests. To visualize the waveform morphology 'discovered' by the predictive model, we pair it with a generative model of the ECG waveform. Together, they reveal a biomarker that is easily visible and robustly predicts sudden cardiac death, but has not to our knowledge been previously described. Tying the biomarker's shape to electrophysiological first principles, we form and preliminarily test a new hypothesis on the mechanism of sudden cardiac death.
Baalbaki R, Shen J, Simon M
… +79 more, Klebach H, Ruhl S, DeVivo J, Wang M, Scholz W, Dada L, Rörup B, Stolzenburg D, Manninen HE, Sommer E, Caudillo-Plath L, Marie G, Friedrich M, Yu W, Leiminger M, Alfaouri D, Amorim A, Arnoldi-Meadows T, Beckmann H, Berntheusel M, Bräkling S, Brasseur Z, Chiu R, Duplissy J, Finkenzeller H, Heinritzi M, Kunkler F, Lamkaddam H, Lopez B, Mahfouz N, Makhmutov V, Martinez M, Marten R, Massabo D, Mauldin R, Mentler B, Müller M, Philippov M, Piedehierro AA, Rato P, Reinecke T, Richter S, Russell DM, Schulze B, Surdu M, Thakur R, Tham YJ, Tian P, Tomé A, Tong Y, Top J, Wagner AC, Wang DS, Wang Y, Ward RX, Weber SK, Welti A, Wu Y, Zauner-Wieczorek M, Zhang J, Curtius J, Donahue NM, El Haddad I, Flagan RC, Hansel A, Harder H, Kürten A, Petäjä T, Schobesberger S, Sipilä M, Volkamer R, Winkler PM, Worsnop DR, Christoudias T, Pozzer A, Kulmala M, Kirkby J, Lehtipalo K, He XC
Dimethylsulfide (DMS; CHSCH) from marine phytoplankton is a major source of atmospheric sulfur . Its oxidation products include sulfuric acid (SA; HSO) and methanesulfonic acid (MSA; CHSOH), which has a higher yield than...Dimethylsulfide (DMS; CHSCH) from marine phytoplankton is a major source of atmospheric sulfur . Its oxidation products include sulfuric acid (SA; HSO) and methanesulfonic acid (MSA; CHSOH), which has a higher yield than SA below 10 °C . Whereas SA is known to drive the formation of new particles , which may subsequently grow and act as cloud condensation nuclei (CCN), the role of MSA remains unclear . Here, in experiments performed under atmospheric conditions at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we show that MSA nucleates together with ammonia (NH) below -10 °C, at rates comparable to SA-NH. Moreover, MSA and SA nucleate synergistically below -10 °C, forming multi-acid molecular clusters with NH. Even at ultra-low NH levels, MSA drives particle growth at or near the kinetic limit below 9 °C and above 40 % relative humidity (RH). Since MSA and SA generally coexist at similar concentrations in cool marine regions, our findings indicate that nucleation rates may be accelerated up to tenfold and growth rates up to twofold compared with SA-NH alone. Our global model simulations indicate that MSA can enhance CCN concentrations, especially in polar regions. We propose that MSA might be an important driver of biogenic particles in cool, pristine marine regions of both the present-day and pre-industrial atmospheres, and yet is unaccounted for in global climate models .
Extreme applications call for materials that are not only strong to withstand thermomechanical loads at temperatures in excess of 2,000 °C (refs. ), but also highly formable at room temperature to allow for processing in...Extreme applications call for materials that are not only strong to withstand thermomechanical loads at temperatures in excess of 2,000 °C (refs. ), but also highly formable at room temperature to allow for processing into complex-shaped parts. The latter excludes brittle ceramics and intermetallic compounds, limiting the selection to highly ductile metals and their alloys, but for them, an adequate strength at ultrahigh temperatures seems unreachable. Here we show a breakthrough in casting alloys that achieve both simultaneously. A boron-stabilized HfO-strengthened Ta-based alloy was carefully crafted using a new boron-intervened in situ oxidation reaction, producing about 50-nm diameter oxide particles dispersed densely and uniformly in the grain interior. The new alloy fills the blank at ultrahigh temperatures in terms of tensile yield strength, around 200 MPa at 2,000 °C and 100 MPa at 2,400 °C, while simultaneously possessing an excellent strength-ductility balance at room temperature (ultimate tensile strength >800 MPa, elongation-to-failure of about 35%), a property combination surpassing all previous refractory (including multi-principal-element) alloys. Moreover, the boron segregation around the oxide nanoparticles imparts excellent thermal stability against coarsening at 2,000-2,400 °C. Our strategy thus goes beyond traditional oxide-dispersion strengthening to enable highly ductile refractory alloys that are capable of load-bearing applications at extreme temperatures.
Stimulator of interferon genes (STING) is an evolutionary conserved immune signalling protein with key roles in host defence, cancer, senescence and inflammation. Downstream of STING, type I interferon, inflammatory cyto...Stimulator of interferon genes (STING) is an evolutionary conserved immune signalling protein with key roles in host defence, cancer, senescence and inflammation. Downstream of STING, type I interferon, inflammatory cytokine signalling and non-canonical autophagy are governed by a multilayered mechanism integrating ligand-induced structural transitions, protein-protein interactions and coordinated intracellular trafficking. Despite its central role in immunity and relevance as therapeutic target, the sequence elements that govern STING (in)activation in cells remain incompletely understood. Here we developed a massively parallel assay to systematically chart the sequence-function landscape of STING. Profiling thousands of single amino-acid variants, we identified structural and functional determinants that shape the immunostimulatory capacity of STING and its ability to translate ligand recognition into distinct signalling outputs. Cryogenic-electron microscopy structures of select STING hyperactive variants revealed new regulatory principles dictating conformational transition from inactive to signalling-competent states of STING. Mutational effects are widespread across the functional landscape and can sensitize STING towards the natural ligand 2'3'-cGAMP or decouple interferon induction from non-canonical autophagy, demonstrating a diversity of possible responses that can be accessed through single point substitutions. Finally, our data showed the clinical and evolutionary relevance of naturally occurring STING protein variants. Collectively, these findings define molecular principles that tune STING activity and chart the landscape of its functional potential across immune contexts.
The design of proteins that bind to small molecules has been challenging because it requires simultaneous optimization of the protein sequence, protein structure and ligand conformation. Current deep-learning algorithms...The design of proteins that bind to small molecules has been challenging because it requires simultaneous optimization of the protein sequence, protein structure and ligand conformation. Current deep-learning algorithms have struggled to navigate this landscape, precluding the zero-shot design of binders. Here we show that by combining two neural networks in an iterative design algorithm, small-molecule binding proteins can be created from scratch with high accuracy. We trained a graph neural network-ligand-aware sequence engineering message-passing neural network (LASErMPNN)-to design compatible protein sequences for an input protein backbone and docked ligand. We paired LASErMPNN with a structure predictor that models a three-dimensional protein-ligand complex for an input protein sequence and ligand identity. The closed-loop iteration of these reciprocal networks optimized sequence-structure-ligand compatibility, and outperformed a comparable design loop using a physics-based energy function. We used our strategy, termed neural iterative selection-expansion (NISE), to design proteins that, using different folds, specifically bind to two chemically distinct small-molecule drugs, exatecan and apixaban, with success rates of 100% and 83%, respectively. The tightest NISE binders had nanomolar-to-picomolar affinities, surpassing those of the next-leading method by 70-fold for exatecan and nearly 10,000-fold for apixaban. LASErMPNN then suggested two amino-acid substitutions that improved the affinity of the tightest exatecan binder by 100-fold without any experimental input. The optimized binder protected the labile lactone ring of exatecan from hydrolysis for days. Our work describes a general recipe for using neural networks to automate the design of small-molecule binding proteins for applications in drug delivery, sensing and catalysis.
The incipient stage of gastrulation in human, when the primitive streak is about to emerge, represents a critical yet underexplored period. Here we present the high-resolution spatial transcriptomic landscape of a human...The incipient stage of gastrulation in human, when the primitive streak is about to emerge, represents a critical yet underexplored period. Here we present the high-resolution spatial transcriptomic landscape of a human embryo at Carnegie stage 6 (approximately 13-14 days post-conception), a stage at which primitive streak remains invisible and gastrulation-derived mesodermal/endodermal progenitors are not yet transcriptomically detected. We identified an anterior visceral endoderm-like hypoblast population, as well as a trifurcated developmental trajectory of the epiblast, progressing towards the amnion, primitive streak and node/prechordal plate/notochord (axial mesoderm) at subsequent developmental stages. Furthermore, our findings challenge the existing paradigms by revealing that primitive haematopoiesis, involving three blood lineages, initiates in human yolk sac before gastrulation, earlier than previously recognized, and that the first blood cells arise from the extra-embryonic mesoderm with a hypoblast rather than epiblast origin. Notably, we identified two spatial zones, each consisting of molecularly distinct yolk sac endoderm and extra-embryonic mesoderm populations, that respectively facilitated the generation of erythro-megakaryocytic lineages and myeloid precursors. These findings provide insights into the onset of gastrulation and the earliest blood formation in humans, with profound implications for advancing stem cell-derived human embryo models and in vitro blood regeneration.