Insight
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Publications in Cell by NOMIS researchers

NOMIS Researcher(s)

Published in

June 20, 2024

Gamete formation and subsequent offspring development often involve extended phases of suspended cellular development or even dormancy. How cells adapt to recover and resume growth remains poorly understood. Here, we visualized budding yeast cells undergoing meiosis by cryo-electron tomography (cryoET) and discovered elaborate filamentous assemblies decorating the nucleus, cytoplasm, and mitochondria. To determine filament composition, we developed a “filament identification” (FilamentID) workflow that combines multiscale cryoET/cryo-electron microscopy (cryoEM) analyses of partially lysed cells or organelles. FilamentID identified the mitochondrial filaments as being composed of the conserved aldehyde dehydrogenase Ald4ALDH2 and the nucleoplasmic/cytoplasmic filaments as consisting of acetyl-coenzyme A (CoA) synthetase Acs1ACSS2. Structural characterization further revealed the mechanism underlying polymerization and enabled us to genetically perturb filament formation. Acs1 polymerization facilitates the recovery of chronologically aged spores and, more generally, the cell cycle re-entry of starved cells. FilamentID is broadly applicable to characterize filaments of unknown identity in diverse cellular contexts.

Research field(s)
Microbiology, Biology

NOMIS Researcher(s)

Published in

May 13, 2024

Retrospective lineage reconstruction of humans predicts that dramatic clonal imbalances in the body can be traced to the 2-cell stage embryo. However, whether and how such clonal asymmetries arise in the embryo is unclear. Here, we performed prospective lineage tracing of human embryos using live imaging, non-invasive cell labeling, and computational predictions to determine the contribution of each 2-cell stage blastomere to the epiblast (body), hypoblast (yolk sac), and trophectoderm (placenta). We show that the majority of epiblast cells originate from only one blastomere of the 2-cell stage embryo. We observe that only one to three cells become internalized at the 8-to-16-cell stage transition. Moreover, these internalized cells are more frequently derived from the first cell to divide at the 2-cell stage. We propose that cell division dynamics and a cell internalization bottleneck in the early embryo establish asymmetry in the clonal composition of the future human body.

Research field(s)
Biology

NOMIS Researcher(s)

Published in

August 17, 2023

The bone marrow in the skull is important for shaping immune responses in the brain and meninges, but its molecular makeup among bones and relevance in human diseases remain unclear. Here, we show that the mouse skull has the most distinct transcriptomic profile compared with other bones in states of health and injury, characterized by a late-stage neutrophil phenotype. In humans, proteome analysis reveals that the skull marrow is the most distinct, with differentially expressed neutrophil-related pathways and a unique synaptic protein signature. 3D imaging demonstrates the structural and cellular details of human skull-meninges connections (SMCs) compared with veins. Last, using translocator protein positron emission tomography (TSPO-PET) imaging, we show that the skull bone marrow reflects inflammatory brain responses with a disease-specific spatial distribution in patients with various neurological disorders. The unique molecular profile and anatomical and functional connections of the skull show its potential as a site for diagnosing, monitoring, and treating brain diseases. © 2023 The Author(s)

Research field(s)
Health Sciences

NOMIS Researcher(s)

Published in

January 19, 2023

Learning has been associated with modifications of synaptic and circuit properties, but the precise changes storing information in mammals have remained largely unclear. We combined genetically targeted voltage imaging with targeted optogenetic activation and silencing of pre- and post-synaptic neurons to study the mechanisms underlying hippocampal behavioral timescale plasticity. In mice navigating a virtual-reality environment, targeted optogenetic activation of individual CA1 cells at specific places induced stable representations of these places in the targeted cells. Optical elicitation, recording, and modulation of synaptic transmission in behaving mice revealed that activity in presynaptic CA2/3 cells was required for the induction of plasticity in CA1 and, furthermore, that during induction of these place fields in single CA1 cells, synaptic input from CA2/3 onto these same cells was potentiated. These results reveal synaptic implementation of hippocampal behavioral timescale plasticity and define a methodology to resolve synaptic plasticity during learning and memory in behaving mammals. © 2022 The Author(s)

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

December 22, 2022

Cerebrospinal fluid (CSF) contains a tightly regulated immune system. However, knowledge is lacking about how CSF immunity is altered with aging or neurodegenerative disease. Here, we performed single-cell RNA sequencing on CSF from 45 cognitively normal subjects ranging from 54 to 82 years old. We uncovered an upregulation of lipid transport genes in monocytes with age. We then compared this cohort with 14 cognitively impaired subjects. In cognitively impaired subjects, downregulation of lipid transport genes in monocytes occurred concomitantly with altered cytokine signaling to CD8 T cells. Clonal CD8 T effector memory cells upregulated C-X-C motif chemokine receptor 6 (CXCR6) in cognitively impaired subjects. The CXCR6 ligand, C-X-C motif chemokine ligand 16 (CXCL16), was elevated in the CSF of cognitively impaired subjects, suggesting CXCL16-CXCR6 signaling as a mechanism for antigen-specific T cell entry into the brain. Cumulatively, these results reveal cerebrospinal fluid immune dysregulation during healthy brain aging and cognitive impairment.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

December 22, 2022

Spatial molecular profiling of complex tissues is essential to investigate cellular function in physiological and pathological states. However, methods for molecular analysis of large biological specimens imaged in 3D are lacking. Here, we present DISCO-MS, a technology that combines whole-organ/whole-organism clearing and imaging, deep-learning-based image analysis, robotic tissue extraction, and ultra-high-sensitivity mass spectrometry. DISCO-MS yielded proteome data indistinguishable from uncleared samples in both rodent and human tissues. We used DISCO-MS to investigate microglia activation along axonal tracts after brain injury and characterized early- and late-stage individual amyloid-beta plaques in a mouse model of Alzheimer’s disease. DISCO-bot robotic sample extraction enabled us to study the regional heterogeneity of immune cells in intact mouse bodies and aortic plaques in a complete human heart. DISCO-MS enables unbiased proteome analysis of preclinical and clinical tissues after unbiased imaging of entire specimens in 3D, identifying diagnostic and therapeutic opportunities for complex diseases. Video abstract: [Figure presented]

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

February 17, 2022

ChRmine, a recently discovered pump-like cation-conducting channelrhodopsin, exhibits puzzling properties (large photocurrents, red-shifted spectrum, and extreme light sensitivity) that have created new opportunities in optogenetics. ChRmine and its homologs function as ion channels but, by primary sequence, more closely resemble ion pump rhodopsins; mechanisms for passive channel conduction in this family have remained mysterious. Here, we present the 2.0 Å resolution cryo-EM structure of ChRmine, revealing architectural features atypical for channelrhodopsins: trimeric assembly, a short transmembrane-helix 3, a twisting extracellular-loop 1, large vestibules within the monomer, and an opening at the trimer interface. We applied this structure to design three proteins (rsChRmine and hsChRmine, conferring further red-shifted and high-speed properties, respectively, and frChRmine, combining faster and more red-shifted performance) suitable for fundamental neuroscience opportunities. These results illuminate the conduction and gating of pump-like channelrhodopsins and point the way toward further structure-guided creation of channelrhodopsins for applications across biology.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

December 23, 2020

The ability to record transient cellular events in the DNA or RNA of cells would enable precise, large-scale analysis, selection, and reprogramming of heterogeneous cell populations. Here, we report a molecular technology for stable genetic tagging of cells that exhibit activity-related increases in intracellular calcium concentration (FLiCRE). We used FLiCRE to transcriptionally label activated neural ensembles in the nucleus accumbens of the mouse brain during brief stimulation of aversive inputs. Using single-cell RNA sequencing, we detected FLiCRE transcripts among the endogenous transcriptome, providing simultaneous readout of both cell-type and calcium activation history. We identified a cell type in the nucleus accumbens activated downstream of long-range excitatory projections. Taking advantage of FLiCRE’s modular design, we expressed an optogenetic channel selectively in this cell type and showed that direct recruitment of this otherwise genetically inaccessible population elicits behavioral aversion. The specificity and minute resolution of FLiCRE enables molecularly informed characterization, manipulation, and reprogramming of activated cellular ensembles.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

April 16, 2020

In this Perspective, Janelle Ayres argues for a paradigm shift in how we think about “health,” toward viewing it as an active process involving mechanisms distinct from those of disease.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

March 19, 2020

Selective autophagy of organelles is critical for cellular differentiation, homeostasis, and organismal health. Autophagy of the ER (ER-phagy) is implicated in human neuropathy but is poorly understood beyond a few autophagosomal receptors and remodelers. By using an ER-phagy reporter and genome-wide CRISPRi screening, we identified 200 high-confidence human ER-phagy factors. Two pathways were unexpectedly required for ER-phagy. First, reduced mitochondrial metabolism represses ER-phagy, which is opposite of general autophagy and is independent of AMPK. Second, ER-localized UFMylation is required for ER-phagy to repress the unfolded protein response via IRE1α. The UFL1 ligase is brought to the ER surface by DDRGK1 to UFMylate RPN1 and RPL26 and preferentially targets ER sheets for degradation, analogous to PINK1-Parkin regulation during mitophagy. Our data provide insight into the cellular logic of ER-phagy, reveal parallels between organelle autophagies, and provide an entry point to the relatively unexplored process of degrading the ER network.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

September 19, 2019

Proteomic profiling of melanomas from patients undergoing immunotherapy reveals key mediators of tumor immunogenicity.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

September 20, 2018

Pathogen virulence exists on a continuum. The strategies that drive symptomatic or asymptomatic infections remain largely unknown. We took advantage of the concept of lethal dose 50 (LD50) to ask which component of individual non-genetic variation between hosts defines whether they survive or succumb to infection. Using the enteric pathogen Citrobacter, we found no difference in pathogen burdens between healthy and symptomatic populations. Iron metabolism-related genes were induced in asymptomatic hosts compared to symptomatic or naive mice. Dietary iron conferred complete protection without influencing pathogen burdens, even at 1000× the lethal dose of Citrobacter. Dietary iron induced insulin resistance, increasing glucose levels in the intestine that were necessary and sufficient to suppress pathogen virulence. A short course of dietary iron drove the selection of attenuated Citrobacter strains that can transmit and asymptomatically colonize naive hosts, demonstrating that environmental factors and cooperative metabolic strategies can drive conversion of pathogens toward commensalism. Defense strategies that are cooperative rather than antagonistic can promote asymptomatic infection and select for reduced virulence in a bacterial pathogen.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

Published in

April 19, 2018

Cytoplasmic FUS aggregates are a pathological hallmark in a subset of patients with frontotemporal dementia (FTD) or amyotrophic lateral sclerosis (ALS). A key step that is disrupted in these patients is nuclear import of FUS mediated by the import receptor Transportin/Karyopherin-β2. In ALS-FUS patients, this is caused by mutations in the nuclear localization signal (NLS) of FUS that weaken Transportin binding. In FTD-FUS patients, Transportin is aggregated, and post-translational arginine methylation, which regulates the FUS-Transportin interaction, is lost. Here, we show that Transportin and arginine methylation have a crucial function beyond nuclear import—namely to suppress RGG/RG-driven phase separation and stress granule association of FUS. ALS-associated FUS-NLS mutations weaken the chaperone activity of Transportin and loss of FUS arginine methylation, as seen in FTD-FUS, promote phase separation, and stress granule partitioning of FUS. Our findings reveal two regulatory mechanisms of liquid-phase homeostasis that are disrupted in FUS-associated neurodegeneration. Phase separation of FUS is regulated by both arginine methylation and binding to the nuclear import receptor Transportin/Karyopherin-β2, and this control can be compromised in the neurodegenerative diseases FTD and ALS.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

February 8, 2018

Protein aggregation and dysfunction of the ubiquitin-proteasome system are hallmarks of many neurodegenerative diseases. Here, we address the elusive link between these phenomena by employing cryo-electron tomography to dissect the molecular architecture of protein aggregates within intact neurons at high resolution. We focus on the poly-Gly-Ala (poly-GA) aggregates resulting from aberrant translation of an expanded GGGGCC repeat in C9orf72, the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. We find that poly-GA aggregates consist of densely packed twisted ribbons that recruit numerous 26S proteasome complexes, while other macromolecules are largely excluded. Proximity to poly-GA ribbons stabilizes a transient substrate-processing conformation of the 26S proteasome, suggesting stalled degradation. Thus, poly-GA aggregates may compromise neuronal proteostasis by driving the accumulation and functional impairment of a large fraction of cellular proteasomes. Neuronal poly-GA aggregates linked to amyotrophic lateral sclerosis and frontotemporal dementia selectively sequester proteasomes.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

November 30, 2017

Internal states of the brain profoundly influence behavior. Fluctuating states such as alertness can be governed by neuromodulation, but the underlying mechanisms and cell types involved are not fully understood. We developed a method to globally screen for cell types involved in behavior by integrating brain-wide activity imaging with high-content molecular phenotyping and volume registration at cellular resolution. We used this method (MultiMAP) to record from 22 neuromodulatory cell types in behaving zebrafish during a reaction-time task that reports alertness. We identified multiple monoaminergic, cholinergic, and peptidergic cell types linked to alertness and found that activity in these cell types was mutually correlated during heightened alertness. We next recorded from and controlled homologous neuromodulatory cells in mice; alertness-related cell-type dynamics exhibited striking evolutionary conservation and modulated behavior similarly. These experiments establish a method for unbiased discovery of cellular elements underlying behavior and reveal an evolutionarily conserved set of diverse neuromodulatory systems that collectively govern internal state. Registration of brain-wide activity measurements with multiple molecular markers at cellular resolution uncovers multiple diverse neuromodulatory pathways linked to brain state.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

September 8, 2016

The reprioritization of feeding motivations during disease is proposed to optimize host defense strategies against infection. Now, Wang et al. identify that sickness-induced anorexia differentially shapes the metabolic requirements of cellular stress adaptations, leading to opposite impact on disease tolerance upon bacterial versus viral infections.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

June 2, 2016

Animal defense strategies against microbes are most often thought of as a function of the immune system, the primary function of which is to sense and kill microbes through the execution of resistance mechanisms. However, this antagonistic view creates complications for our understanding of beneficial host-microbe interactions. Pathogenic microbes are described as employing a few common behaviors that promote their fitness at the expense of host health and fitness. Here, a complementary framework is proposed to suggest that, in addition to pathogens, beneficial microbes have evolved behaviors to manipulate host processes in order to promote their own fitness and do so through the promotion of host health and fitness. In this Perspective, I explore the idea that patterns or behaviors traditionally ascribed to pathogenic microbes are also employed by beneficial microbes to promote host tolerance defense strategies. Such strategies would promote host health without having a negative impact on microbial fitness and would thereby yield cooperative evolutionary dynamics that are likely required to drive mutualistic co-evolution of hosts and microbes.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

NOMIS Researcher(s)

Published in

August 14, 2014

The homeostasis of multicellular organisms requires terminally differentiated cells to preserve their lineage specificity. However, it is unclear whether mechanisms exist to actively protect cell identity in response to environmental cues that confer functional plasticity. Regulatory T (Treg) cells, specified by the transcription factor Foxp3, are indispensable for immune system homeostasis. Here, we report that conserved noncoding sequence 2 (CNS2), a CpG-rich Foxp3 intronic cis-element specifically demethylated in mature Tregs, helps maintain immune homeostasis and limit autoimmune disease development by protecting Treg identity in response to signals that shape mature Treg functions and drive their initial differentiation. In activated Tregs, CNS2 helps protect Foxp3 expression from destabilizing cytokine conditions by sensing TCR/NFAT activation, which facilitates the interaction between CNS2 and Foxp3 promoter. Thus, epigenetically marked cis-elements can protect cell identity by sensing key environmental cues central to both cell identity formation and functional plasticity without interfering with initial cell differentiation. © 2014 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology