Comment in Cell. 2022 Aug 4;185(16):2846-2848. Nat Rev Cancer. 2022 Dec;22(12):662.

Comment in Cell. 2022 Aug 4;185(16):2848-2849.

Here, we report inducible mosaic animal for perturbation (iMAP), a transgenic platform enabling in situ CRISPR targeting of at least 100 genes in parallel throughout the mouse body. iMAP combines Cre-loxP and CRISPR-Cas9 technologies and utilizes a germline-transmitted transgene carrying a large array of individually floxed, tandemly linked gRNA-coding units. Cre-mediated recombination triggers expression of all the gRNAs in the array but only one of them per cell, converting the mice to mosaic organisms suitable for phenotypic characterization and also for high-throughput derivation of conventional single-gene perturbation lines via breeding. Using gRNA representation as a readout, we mapped a miniature Perturb-Atlas cataloging the perturbations of 90 genes across 39 tissues, which yields rich insights into context-dependent gene functions and provides a glimpse of the potential of iMAP in genome decoding.

Comment in Nat Rev Microbiol. 2022 Oct;20(10):576. Cell Host Microbe. 2022 Oct 12;30(10):1352-1353. Nature. 2022 Dec;612(7939):220-221.

Non-allelic recombination between homologous repetitive elements contributes to evolution and human genetic disorders. Here, we combine short- and long-DNA read sequencing of repeat elements with a new bioinformatics pipeline to show that somatic recombination of Alu and L1 elements is widespread in the human genome. Our analysis uncovers tissue-specific non-allelic homologous recombination hallmarks; moreover, we find that centromeres and cancer-associated genes are enriched for retroelements that may act as recombination hotspots. We compare recombination profiles in human-induced pluripotent stem cells and differentiated neurons and find that the neuron-specific recombination of repeat elements accompanies chromatin changes during cell-fate determination. Finally, we report that somatic recombination profiles are altered in Parkinson's and Alzheimer's disease, suggesting a link between retroelement recombination and genomic instability in neurodegeneration. This work highlights a significant contribution of the somatic recombination of repeat elements to genomic diversity in health and disease.

The surprising discovery that the diatomic gas nitric oxide (NO) is generated by mammalian cells and serves to regulate a multitude of physiological processes has continued to fascinate biologists for almost four decades. The biochemistry of NO is complex, and novel insights into the control of NO biosynthesis and mechanisms of signal transduction are continuously emerging. NO is a key regulator of cardiovascular function, metabolism, neurotransmission, immunity, and more, and aberrant NO signaling is a central feature of many major disorders including cardiovascular disease, diabetes, and cancer. Here, we discuss the basics of NO biology emphasizing recent advances in the field including novel means of increasing NO bioactivity with therapeutic and nutritional implications.

Comment in Nature. 2022 Sep;609(7928):683-684.

Author information: (1)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Division of Medical Sciences and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA. Electronic address: rlcollins@g.harvard.edu. (2)Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics, Division of Human Genetics, Perelman School of Medicine, Philadelphia, PA 19104, USA. (3)Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland. (4)Estonian Genome Centre, Institute of Genomics, University of Tartu, 51010 Tartu, Estonia; Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia. (5)GeneDx, Gaithersburg, MD 20877, USA. (6)Division of Genetic Medicine, Department of Medicine, and Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA. (7)Cologne Center for Genomics, University of Cologne, 51149 Cologne, Germany. (8)Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Division of Medical Sciences and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA. (9)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA. (10)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA. (11)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA. (12)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA. (13)Advanced Center for Translational and Genetic Medicine, Stanley Manne Children's Research Institute, Lurie Children's Hospital, Chicago, IL 60611, USA; Departments of Pediatrics and Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. (14)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA. (15)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Division of Medical Sciences and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA. (16)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Division of Medical Sciences and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Human Genetics Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10, UK. (17)Human Genetics Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10, UK. (18)Estonian Genome Centre, Institute of Genomics, University of Tartu, 51010 Tartu, Estonia. (19)Avenue 80, Inc., Fort Wayne, IN 46802, USA. (20)Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA. (21)Cologne Center for Genomics, University of Cologne, 51149 Cologne, Germany; Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA. (22)Division of Genetic Medicine, Department of Medicine, and Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Precision Medicine, Department of Biomedical Informatics, and Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA. (23)Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland. (24)Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland; Center for Primary Care and Public Health, University of Lausanne, 1015 Lausanne, Switzerland; Department of Computational Biology, University of Lausanne, 1015 Lausanne, Switzerland. (25)Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Division of Medical Sciences and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA. (26)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA 02114, USA. Electronic address: hbrand@broadinstitute.org. (27)Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA; Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA. Electronic address: talkowsk@broadinstitute.org.

Wheat crops are frequently devastated by pandemic stripe rust caused by Puccinia striiformis f. sp. tritici (Pst). Here, we identify and characterize a wheat receptor-like cytoplasmic kinase gene, TaPsIPK1, that confers susceptibility to this pathogen. PsSpg1, a secreted fungal effector vital for Pst virulence, can bind TaPsIPK1, enhance its kinase activity, and promote its nuclear localization, where it phosphorylates the transcription factor TaCBF1d for gene regulation. The phosphorylation of TaCBF1d switches its transcriptional activity on the downstream genes. CRISPR-Cas9 inactivation of TaPsIPK1 in wheat confers broad-spectrum resistance against Pst without impacting important agronomic traits in two years of field tests. The disruption of TaPsIPK1 leads to immune priming without constitutive activation of defense responses. Taken together, TaPsIPK1 is a susceptibility gene known to be targeted by rust effectors, and it has great potential for developing durable resistance against rust by genetic modifications.

Horizontal gene transfer (HGT) is an important evolutionary force shaping prokaryotic and eukaryotic genomes. HGT-acquired genes have been sporadically reported in insects, a lineage containing >50% of animals. We systematically examined HGT in 218 high-quality genomes of diverse insects and found that they acquired 1,410 genes exhibiting diverse functions, including many not previously reported, via 741 distinct transfers from non-metazoan donors. Lepidopterans had the highest average number of HGT-acquired genes. HGT-acquired genes containing introns exhibited substantially higher expression levels than genes lacking introns, suggesting that intron gains were likely involved in HGT adaptation. Lastly, we used the CRISPR-Cas9 system to edit the prevalent unreported gene LOC105383139, which was transferred into the last common ancestor of moths and butterflies. In diamondback moths, males lacking LOC105383139 courted females significantly less. We conclude that HGT has been a major contributor to insect adaptation.

We studied the prevalent cytotoxic CD8 T cell response mounted against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike glycoprotein269-277 epitope (sequence YLQPRTFLL) via the most frequent human leukocyte antigen (HLA) class I worldwide, HLA A∗02. The Spike P272L mutation that has arisen in at least 112 different SARS-CoV-2 lineages to date, including in lineages classified as "variants of concern," was not recognized by the large CD8 T cell response seen across cohorts of HLA A∗02+ convalescent patients and individuals vaccinated against SARS-CoV-2, despite these responses comprising of over 175 different individual T cell receptors. Viral escape at prevalent T cell epitopes restricted by high frequency HLAs may be particularly problematic when vaccine immunity is focused on a single protein such as SARS-CoV-2 Spike, providing a strong argument for inclusion of multiple viral proteins in next generation vaccines and highlighting the need for monitoring T cell escape in new SARS-CoV-2 variants.

The currently circulating Omicron sub-variants are the SARS-CoV-2 strains with the highest number of known mutations. Herein, we found that human angiotensin-converting enzyme 2 (hACE2) binding affinity to the receptor-binding domains (RBDs) of the four early Omicron sub-variants (BA.1, BA.1.1, BA.2, and BA.3) follows the order BA.1.1 > BA.2 > BA.3 ≈ BA.1. The complex structures of hACE2 with RBDs of BA.1.1, BA.2, and BA.3 reveal that the higher hACE2 binding affinity of BA.2 than BA.1 is related to the absence of the G496S mutation in BA.2. The R346K mutation in BA.1.1 majorly affects the interaction network in the BA.1.1 RBD/hACE2 interface through long-range alterations and contributes to the higher hACE2 affinity of the BA.1.1 RBD than the BA.1 RBD. These results reveal the structural basis for the distinct hACE2 binding patterns among BA.1.1, BA.2, and BA.3 RBDs.

Comment on Cell. 2022 Aug 4;185(16):3041-3055.e25.

Historically Black colleges and universities (HBCUs) offer high-quality education and produce leaders from various backgrounds, mainly being African American. Predominately White institutions can utilize practices that make HBCUs successful to mentor and graduate students of all backgrounds. We also suggest ways to bolster HBCUs so they can train more students.

Comment on Cell. 2022 Aug 4;185(16):2918-2935.e29.

Comment on Cell. 2022 Aug 4;185(16):2899-2917.e31.

Comment in Curr Biol. 2022 Aug 22;32(16):R891-R894.

The T cell receptor (TCR) expressed by T lymphocytes initiates protective immune responses to pathogens and tumors. To explore the structural basis of how TCR signaling is initiated when the receptor binds to peptide-loaded major histocompatibility complex (pMHC) molecules, we used cryogenic electron microscopy to determine the structure of a tumor-reactive TCRαβ/CD3δγε2ζ2 complex bound to a melanoma-specific human class I pMHC at 3.08 Å resolution. The antigen-bound complex comprises 11 subunits stabilized by multivalent interactions across three structural layers, with clustered membrane-proximal cystines stabilizing the CD3-εδ and CD3-εγ heterodimers. Extra density sandwiched between transmembrane helices reveals the involvement of sterol lipids in TCR assembly. The geometry of the pMHC/TCR complex suggests that efficient TCR scanning of pMHC requires accurate pre-positioning of T cell and antigen-presenting cell membranes. Comparisons of the ligand-bound and unliganded receptors, along with molecular dynamics simulations, indicate that TCRs can be triggered in the absence of spontaneous structural rearrangements.

Comment in Cell. 2022 Aug 18;185(17):3079-3081. Nat Rev Neurosci. 2022 Oct;23(10):583.

Comment in Cell. 2022 Aug 18;185(17):3081-3083.

The immense interindividual clinical variability during any infection is a long-standing enigma. Inborn errors of IFN-γ and IFN-α/β immunity underlying rare infections with weakly virulent mycobacteria and seasonal influenza virus have inspired studies of two common infections: tuberculosis and COVID-19. A TYK2 genotype impairing IFN-γ production accounts for about 1% of tuberculosis cases, and autoantibodies neutralizing IFN-α/β account for about 15% of critical COVID-19 cases. The discovery of inborn errors and mechanisms underlying rare infections drove the identification of common monogenic or autoimmune determinants of related common infections. This "rare-to-common" genetic and mechanistic approach to infectious diseases may be of heuristic value.

Mice deficient for all ten-eleven translocation (TET) genes exhibit early gastrulation lethality. However, separating cause and effect in such embryonic failure is challenging. To isolate cell-autonomous effects of TET loss, we used temporal single-cell atlases from embryos with partial or complete mutant contributions. Strikingly, when developing within a wild-type embryo, Tet-mutant cells retain near-complete differentiation potential, whereas embryos solely comprising mutant cells are defective in epiblast to ectoderm transition with degenerated mesoderm potential. We map de-repressions of early epiblast factors (e.g., Dppa4 and Gdf3) and failure to activate multiple signaling from nascent mesoderm (Lefty, FGF, and Notch) as likely cell-intrinsic drivers of TET loss phenotypes. We further suggest loss of enhancer demethylation as the underlying mechanism. Collectively, our work demonstrates an unbiased approach for defining intrinsic and extrinsic embryonic gene function based on temporal differentiation atlases and disentangles the intracellular effects of the demethylation machinery from its broader tissue-level ramifications.

Comment in Nat Rev Mol Cell Biol. 2022 Oct;23(10):641. Mol Cell. 2022 Sep 1;82(17):3124-3125.

Live bacterial therapeutics (LBTs) could reverse diseases by engrafting in the gut and providing persistent beneficial functions in the host. However, attempts to functionally manipulate the gut microbiome of conventionally raised (CR) hosts have been unsuccessful because engineered microbial organisms (i.e., chassis) have difficulty in colonizing the hostile luminal environment. In this proof-of-concept study, we use native bacteria as chassis for transgene delivery to impact CR host physiology. Native Escherichia coli bacteria isolated from the stool cultures of CR mice were modified to express functional genes. The reintroduction of these strains induces perpetual engraftment in the intestine. In addition, engineered native E. coli can induce functional changes that affect physiology of and reverse pathology in CR hosts months after administration. Thus, using native bacteria as chassis to "knock in" specific functions allows mechanistic studies of specific microbial activities in the microbiome of CR hosts and enables LBT with curative intent.

How mis-regulated chromatin directly impacts human immune disorders is poorly understood. Speckled Protein 140 (SP140) is an immune-restricted PHD and bromodomain-containing epigenetic "reader," and SP140 loss-of-function mutations associate with Crohn's disease (CD), multiple sclerosis (MS), and chronic lymphocytic leukemia (CLL). However, the relevance of these mutations and mechanisms underlying SP140-driven pathogenicity remains unexplored. Using a global proteomic strategy, we identified SP140 as a repressor of topoisomerases (TOPs) that maintains heterochromatin and macrophage fate. In humans and mice, SP140 loss resulted in unleashed TOP activity, de-repression of developmentally silenced genes, and ultimately defective microbe-inducible macrophage transcriptional programs and bacterial killing that drive intestinal pathology. Pharmacological inhibition of TOP1/2 rescued these defects. Furthermore, exacerbated colitis was restored with TOP1/2 inhibitors in Sp140-/- mice, but not wild-type mice, in vivo. Collectively, we identify SP140 as a TOP repressor and reveal repurposing of TOP inhibition to reverse immune diseases driven by SP140 loss.

Comment on Cell. 2022 Aug 18;185(17):3153-3168.e18.

Copyright © 2022. Published by Elsevier Inc.

Comment on Cell. 2022 Aug 18;185(17):3124-3137.e15.

Comment on Cell. 2022 Aug 18;185(17):3066-3069.

Comment in Cell. 2022 Aug 18;185(17):3083-3085.

Comment in Curr Biol. 2022 Sep 12;32(17):R923-R926. Cell Host Microbe. 2023 Jan 11;31(1):3-5.

Comment on Cell. 2022 Aug 18;185(17):3104-3123.e28.

Many organizations persist in working with others that engage in known, remediable structural discrimination. We name this practice interorganizational structural discrimination (ISD) and argue it is a pivotal contributor to inequities in science and medicine. We urge organizations to leverage their relationships and demand progress from collaborators.

Abbie Richards is an active scientific communicator on TikTok who posts videos to communicate climate science and to combat misinformation. Cell editor Jia Cheng chatted with Abbie Richards to get her viewpoint on scientific communication through social media. Annotated excerpts from this conversation are presented below, and the full conversation is available with the article online.

Oakleaf butterflies in the genus Kallima have a polymorphic wing phenotype, enabling these insects to masquerade as dead leaves. This iconic example of protective resemblance provides an interesting evolutionary paradigm that can be employed to study biodiversity. We integrated multi-omic data analyses and functional validation to infer the evolutionary history of Kallima species and investigate the genetic basis of their variable leaf wing patterns. We find that Kallima butterflies diversified in the eastern Himalayas and dispersed to East and Southeast Asia. Moreover, we find that leaf wing polymorphism is controlled by the wing patterning gene cortex, which has been maintained in Kallima by long-term balancing selection. Our results provide macroevolutionary and microevolutionary insights into a model species originating from a mountain ecosystem.