ALBERT

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Beiyun C. Liu, Joseph Sarhan, Alexander Panda, Hayley I. Muendlein, Vladimir Ilyukha, Jörn Coers, Masahiro Yamamoto, Ralph R. Isberg, Alexander Poltorak Legionella pneumophila elicits caspase-11-driven macrophage pyroptosis through guanylate-binding proteins (GBPs) encoded on chromosome 3. It has been proposed that microbe-driven IFN upregulates GBPs to facilitate pathogen vacuole rupture and bacteriolysis preceding caspase-11 activation. We show here that macrophage death occurred independently of microbial-induced IFN signaling and that GBPs are dispensable for pathogen vacuole rupture. Instead, the host-intrinsic IFN status sustained sufficient GBP expression levels to drive caspase-1 and caspase-11 activation in response to cytosol-exposed bacteria. In addition, endogenous GBP levels were sufficient for the release of DNA from cytosol-exposed bacteria, preceding the cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) pathway for Ifnb induction. Mice deficient for chromosome 3 GBPs were unable to mount a rapid IL-1/chemokine (C-X-C motif) ligand 1 (CXCL1) response during Legionella -induced pneumonia, with defective bacterial clearance. Our results show that rapid GBP activity is controlled by host-intrinsic cytokine signaling and that GBP activities precede immune amplification responses, including IFN induction, inflammasome activation, and cell death. Graphical abstract Teaser Guanylate-binding proteins act upstream of many cytosolic pathogen sensors. It is assumed that infection-associated IFN signaling precedes GBP induction. Liu et al. find that host-intrinsic IFN signaling maintains GBPs in naive macrophages to mediate the disruption of cytosol-accessible bacteria. The findings elucidate a crucial role of tonic cytokines in maintaining immune readiness.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Lin Xu, Yanbin Zheng, Jing Liu, Dinesh Rakheja, Sydney Singleterry, Theodore W. Laetsch, Jack F. Shern, Javed Khan, Timothy J. Triche, Douglas S. Hawkins, James F. Amatruda, Stephen X. Skapek Identifying oncogenic drivers and tumor suppressors remains a challenge in many forms of cancer, including rhabdomyosarcoma. Anticipating gene expression alterations resulting from DNA copy-number variants to be particularly important, we developed a computational and experimental strategy incorporating a Bayesian algorithm and CRISPR/Cas9 “mini-pool” screen that enables both genome-scale assessment of disease genes and functional validation. The algorithm, called iExCN, identified 29 rhabdomyosarcoma drivers and suppressors enriched for cell-cycle and nucleic-acid-binding activities. Functional studies showed that many iExCN genes represent rhabdomyosarcoma line-specific or shared vulnerabilities. Complementary experiments addressed modes of action and demonstrated coordinated repression of multiple iExCN genes during skeletal muscle differentiation. Analysis of two separate cohorts revealed that the number of iExCN genes harboring copy-number alterations correlates with survival. Our findings highlight rhabdomyosarcoma as a cancer in which multiple drivers influence disease biology and demonstrate a generalizable capacity for iExCN to unmask disease genes in cancer. Graphical abstract Teaser Xu et al. use an integrative computational pipeline (iExCN) to identify 25 candidate oncogenic driver genes and 4 tumor suppressors in rhabdomyosarcoma, and many are validated in a CRISPR/Cas9 mini-pool screen. Functional assays and correlation with survival indicate that cooperative interactions across iExCN genes contribute to disease biology, including differentiation arrest.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Yuichi Sekine, Alexander Lin-Moore, Devon M. Chenette, Xingxing Wang, Zhaoxin Jiang, William B. Cafferty, Marc Hammarlund, Stephen M. Strittmatter

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Giuliano Ferrero, Christopher B. Mahony, Eléonore Dupuis, Laurent Yvernogeau, Elodie Di Ruggiero, Magali Miserocchi, Marianne Caron, Catherine Robin, David Traver, Julien Y. Bertrand, Valérie Wittamer Microglia, the tissue-resident macrophages of the CNS, represent major targets for therapeutic intervention in a wide variety of neurological disorders. Efficient reprogramming protocols to generate microglia-like cells in vitro using patient-derived induced pluripotent stem cells will, however, require a precise understanding of the cellular and molecular events that instruct microglial cell fates. This remains a challenge since the developmental origin of microglia during embryogenesis is controversial. Here, using genetic tracing in zebrafish, we uncover primitive macrophages as the unique source of embryonic microglia. We also demonstrate that this initial population is transient, with primitive microglia later replaced by definitive microglia that persist throughout adulthood. The adult wave originates from cmyb -dependent hematopoietic stem cells. Collectively, our work challenges the prevailing model establishing erythro-myeloid progenitors as the sole and direct microglial precursor and provides further support for the existence of multiple waves of microglia, which originate from distinct hematopoietic precursors. Graphical abstract Teaser Using zebrafish to investigate microglia ontogeny during vertebrate development, Ferrero et al. find that embryonic “primitive” microglia exclusively derive from primitive macrophages, while adult “definitive” microglia originate from cmyb -dependent hematopoietic stem cells.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Eric Wong, Ren-Huan Xu, Daniel Rubio, Avital Lev, Colby Stotesbury, Min Fang, Luis J. Sigal Circulating natural killer (NK) cells help protect the host from lympho-hematogenous acute viral diseases by rapidly entering draining lymph nodes (dLNs) to curb virus dissemination. Here, we identify a highly choreographed mechanism underlying this process. Using footpad infection with ectromelia virus, a pathogenic DNA virus of mice, we show that TLR9/MyD88 sensing induces NKG2D ligands in virus-infected, skin-derived migratory dendritic cells (mDCs) to induce production of IFN-γ by classical NK cells and other types of group 1 innate lymphoid cells (ILCs) already in dLNs, via NKG2D. Uninfected inflammatory monocytes, also recruited to dLNs by mDCs in a TLR9/MyD88-dependent manner, respond to IFN-γ by secreting CXCL9 for optimal CXCR3-dependent recruitment of circulating NK cells. This work unveils a TLR9/MyD88-dependent mechanism whereby in dLNs, three cell types—mDCs, group 1 ILCs (mostly NK cells), and inflammatory monocytes—coordinate the recruitment of protective circulating NK cells to dLNs. Graphical abstract Teaser Wong et al. show that infected migratory dendritic cells (mDCs) in draining lymph nodes (dLNs) upregulate NKG2D ligands through TLR9/MyD88. This results in NKG2D-dependent IFN-γ production by group 1 innate lymphoid cells, mostly NK cells. IFN-γ induces CXCL9 in uninfected inflammatory monocytes, leading to the recruitment of protective NK cells to dLNs.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Taylor W. Schmitz, Marieke Mur, Meghmik Aghourian, Marc-Andre Bedard, R. Nathan Spreng The cholinergic neurons of the basal forebrain (BF) provide virtually all of the brain’s cortical and amygdalar cholinergic input. They are particularly vulnerable to neuropathology in early Alzheimer’s disease (AD) and may trigger the emergence of neuropathology in their cortico-amygdalar projection system through cholinergic denervation and trans -synaptic spreading of misfolded proteins. We examined whether longitudinal degeneration within the BF can explain longitudinal cortico-amygdalar degeneration in older human adults with abnormal cerebrospinal fluid biomarkers of AD neuropathology. We focused on two BF subregions, which are known to innervate cortico-amygdalar regions via two distinct macroscopic cholinergic projections. To further assess whether structural degeneration of these regions in AD reflects cholinergic denervation, we used the [ 18 F] FEOBV radiotracer, which binds to cortico-amygdalar cholinergic terminals. We found that the two BF subregions explain spatially distinct patterns of cortico-amygdalar degeneration, which closely reflect their cholinergic projections, and overlap with [ 18 F] FEOBV indices of cholinergic denervation. Graphical abstract Teaser Among older adults in prodromal stages of Alzheimer’s disease, Schmitz et al. show that longitudinal degeneration within sub-regions of the basal forebrain covaries with cortico-amygdalar topographies of both structural degeneration and cholinergic denervation. The findings support the view that loss of cortico-amygdalar cholinergic input is a pivotal event in AD progression.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Lucas J.T. Kaaij, Robin H. van der Weide, René F. Ketting, Elzo de Wit The spatial organization of chromosomes is critical in establishing gene expression programs. We generated in situ Hi-C maps throughout zebrafish development to gain insight into higher-order chromatin organization and dynamics. Zebrafish chromosomes segregate in active and inactive chromatin (A/B compartments), which are further organized into topologically associating domains (TADs). Zebrafish A/B compartments and TADs have genomic features similar to those of their mammalian counterparts, including evolutionary conservation and enrichment of CTCF binding sites at TAD borders. At the earliest time point, when there is no zygotic transcription, the genome is highly structured. After zygotic genome activation (ZGA), the genome loses structural features, which are re-established throughout early development. Despite the absence of structural features, we see clustering of super-enhancers in the 3D genome. Our results provide insight into vertebrate genome organization and demonstrate that the developing zebrafish embryo is a powerful model system to study the dynamics of nuclear organization. Graphical abstract Teaser How do developing zebrafish embryos organize their genome? Kaaij et al. show that, early in development, when there is no transcription, the genome is highly structured; however, when the zygotic genome is activated, this organization is lost. Later in development, the genome again adopts a structured organization.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Yuji Matsuoka, Antónia Monteiro The cuticular skeleton of a butterfly wing scale cell is an exquisitely finely sculpted material that can contain pigments, produce structural colors, or both. While cuticle rigidity and pigmentation depend on the products of the melanin pathway, little is known about whether genes in this pathway also play a role in the development of specific scale morphologies. Here, we use CRISPR/Cas9 to show that knockout mutations in five genes that function in the melanin pathway affect both the fine structure and the coloration of the wing scales. Most dramatically, mutations in the yellow gene lead to extra horizontal laminae on the surface of scales, whereas mutations in DDC gene lead to taller and sheet-like vertical laminae throughout each scale. We identify genes affecting the development of color and scale morphology, the regulation and pleiotropic effects of which may be important in creating and limiting the diversity of the structural and pigmentary colors observed in butterflies. Graphical abstract Teaser Matsuoka and Monteiro discover that deletions of the yellow and DDC melanin genes alter both the color and the morphology of Bicyclus anynana wing scales. This study identifies genes that regulate the intricate morphology of wing scales.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Lars Schlotawa, Michaela Wachs, Olaf Bernhard, Franz J. Mayer, Thomas Dierks, Bernhard Schmidt, Karthikeyan Radhakrishnan Multiple sulfatase deficiency (MSD) is a fatal, inherited lysosomal storage disorder characterized by reduced activities of all sulfatases in patients. Sulfatases require a unique post-translational modification of an active-site cysteine to formylglycine that is catalyzed by the formylglycine-generating enzyme (FGE). FGE mutations that affect intracellular protein stability determine residual enzyme activity and disease severity in MSD patients. Here, we show that protein disulfide isomerase (PDI) plays a pivotal role in the recognition and quality control of MSD-causing FGE variants. Overexpression of PDI reduces the residual activity of unstable FGE variants, whereas inhibition of PDI function rescues the residual activity of sulfatases in MSD fibroblasts. Mass spectrometric analysis of a PDI+FGE variant covalent complex allowed determination of the molecular signature for FGE recognition by PDI. Our findings highlight the role of PDI as a disease modifier in MSD, which may also be relevant for other ER-associated protein folding pathologies. Graphical abstract Teaser Impaired activity of misfolded formylglycine-generating enzyme (FGE) results in multiple sulfatase deficiency (MSD) in humans. Schlotawa et al. show that recognition and quality control of misfolded FGE by protein disulfide isomerase (PDI) play a crucial role in the manifestation of MSD as a severe disease.

Description: Publication date: 3 July 2018 Source: Cell Reports, Volume 24, Issue 1 Author(s): Sari Tojkander, Katarzyna Ciuba, Pekka Lappalainen Stress fibers are contractile actomyosin bundles that guide cell adhesion, migration, and morphogenesis. Their assembly and alignment are under precise mechanosensitive control. Thus, stress fiber networks undergo rapid modification in response to changes in biophysical properties of the cell’s surroundings. Stress fiber maturation requires mechanosensitive activation of 5′AMP-activated protein kinase (AMPK), which phosphorylates vasodilator-stimulated phosphoprotein (VASP) to inhibit actin polymerization at focal adhesions. Here, we identify Ca 2+ -calmodulin-dependent kinase kinase 2 (CaMKK2) as a critical upstream factor controlling mechanosensitive AMPK activation. CaMKK2 and Ca 2+ influxes were enriched around focal adhesions at the ends of contractile stress fibers. Inhibition of either CaMKK2 or mechanosensitive Ca 2+ channels led to defects in phosphorylation of AMPK and VASP, resulting in a loss of contractile bundles and a decrease in cell-exerted forces. These data provide evidence that Ca 2+ , CaMKK2, AMPK, and VASP form a mechanosensitive signaling cascade at focal adhesions that is critical for stress fiber assembly. Graphical abstract Teaser Contractile actomyosin bundles control cell morphology, adhesion, and migration. Tojkander et al. show that the maturation of actomyosin bundles occurs through activation of local, mechanosensitive Ca 2+ influx that triggers CaMKK2/AMPK-dependent signaling cascade at focal adhesions.