scholarly journals Fluctuating fitness shapes the clone-size distribution of immune repertoires

2015 ◽  
Vol 113 (2) ◽  
pp. 274-279 ◽  
Author(s):  
Jonathan Desponds ◽  
Thierry Mora ◽  
Aleksandra M. Walczak
Keyword(s):  
T Cells ◽  
Cell Fate ◽  
Single Cells ◽  
Adaptive Immune System ◽  
Cell Types ◽  
Power Law Distribution ◽  
Clone Size ◽  
Environmental Signals ◽  
Somatic Evolution ◽  
Effective Models

The adaptive immune system relies on the diversity of receptors expressed on the surface of B- and T cells to protect the organism from a vast amount of pathogenic threats. The proliferation and degradation dynamics of different cell types (B cells, T cells, naive, memory) is governed by a variety of antigenic and environmental signals, yet the observed clone sizes follow a universal power-law distribution. Guided by this reproducibility we propose effective models of somatic evolution where cell fate depends on an effective fitness. This fitness is determined by growth factors acting either on clones of cells with the same receptor responding to specific antigens, or directly on single cells with no regard for clones. We identify fluctuations in the fitness acting specifically on clones as the essential ingredient leading to the observed distributions. Combining our models with experiments, we characterize the scale of fluctuations in antigenic environments and we provide tools to identify the relevant growth signals in different tissues and organisms. Our results generalize to any evolving population in a fluctuating environment.

scholarly journals Fluctuating fitness shapes the clone size distribution of immune repertoires

2015 ◽  
Author(s):  
Jonathan Desponds ◽  
Thierry Mora ◽  
Aleksandra Walczak
Keyword(s):  
T Cells ◽  
Cell Fate ◽  
Single Cells ◽  
Adaptive Immune System ◽  
Cell Types ◽  
Power Law Distribution ◽  
Clone Size ◽  
Environmental Signals ◽  
Somatic Evolution ◽  
Effective Models

The adaptive immune system relies on the diversity of receptors expressed on the surface of B and T-cells to protect the organism from a vast amount of pathogenic threats. The proliferation and degradation dynamics of different cell types (B cells, T cells, naive, memory) is governed by a variety of antigenic and environmental signals, yet the observed clone sizes follow a universal power law distribution. Guided by this reproducibility we propose effective models of somatic evolution where cell fate depends on an effective fitness. This fitness is determined by growth factors acting either on clones of cells with the same receptor responding to specific antigens, or directly on single cells with no regards for clones. We identify fluctuations in the fitness acting specifically on clones as the essential ingredient leading to the observed distributions. Combining our models with experiments we characterize the scale of fluctuations in antigenic environments and we provide tools to identify the relevant growth signals in different tissues and organisms. Our results generalize to any evolving population in a fluctuating environment.

scholarly journals A new role for Notch in the control of polarity and asymmetric cell division of developing T cells

2019 ◽  
Author(s):  
Mirren Charnley ◽  
Mandy Ludford-Menting ◽  
Kim Pham ◽  
Sarah M. Russell
Keyword(s):  
T Cells ◽  
Cell Division ◽  
Cell Fate ◽  
Asymmetric Cell Division ◽  
Single Cells ◽  
Cell Types ◽  
Notch Signalling ◽  
Pass Through ◽  
Fate Determinants ◽  
Different Cell Types

AbstractA fundamental question in biology is how single cells can reliably produce progeny of different cell types. Notch signalling frequently facilitates fate determination. Asymmetric cell division (ACD) often controls segregation of Notch signalling by imposing unequal inheritance of regulators of Notch. Here, we assessed the functional relationship between Notch and ACD in mouse T cell development. To attain immunological specificity, developing T cells must pass through a pivotal stage termed β-selection, which involves Notch signalling and ACD. We assessed functional interactions between Notch and ACD during β-selection using direct presentation of Notch ligands, DL1 and DL4, and pharmacological inhibition of Notch signalling. Contrary to prevailing models, we find Notch controls distribution of Notch1 itself and cell fate determinants, α-Adaptin and Numb. Notch and CXCR4 signalling cooperated to drive polarity during division. Thus, Notch signalling directly orchestrates ACD, and Notch1 is differentially inherited by sibling cells.

scholarly journals The Roles of Chromatin Accessibility in Regulating the Candida albicans White-Opaque Phenotypic Switch

2021 ◽  
Vol 7 (1) ◽  
pp. 37
Author(s):  
Mohammad N. Qasim ◽  
Ashley Valle Arevalo ◽  
Clarissa J. Nobile ◽  
Aaron D. Hernday
Keyword(s):  
Candida Albicans ◽  
Cell Fate ◽  
Cell Types ◽  
Chromatin Accessibility ◽  
Phenotypic Switching ◽  
Phenotypic Switch ◽  
Chromatin Remodelers ◽  
Environmental Signals ◽  
Cell Fate Decisions ◽  
Simple Model System

Candida albicans, a diploid polymorphic fungus, has evolved a unique heritable epigenetic program that enables reversible phenotypic switching between two cell types, referred to as “white” and “opaque”. These cell types are established and maintained by distinct transcriptional programs that lead to differences in metabolic preferences, mating competencies, cellular morphologies, responses to environmental signals, interactions with the host innate immune system, and expression of approximately 20% of genes in the genome. Transcription factors (defined as sequence specific DNA-binding proteins) that regulate the establishment and heritable maintenance of the white and opaque cell types have been a primary focus of investigation in the field; however, other factors that impact chromatin accessibility, such as histone modifying enzymes, chromatin remodelers, and histone chaperone complexes, also modulate the dynamics of the white-opaque switch and have been much less studied to date. Overall, the white-opaque switch represents an attractive and relatively “simple” model system for understanding the logic and regulatory mechanisms by which heritable cell fate decisions are determined in higher eukaryotes. Here we review recent discoveries on the roles of chromatin accessibility in regulating the C. albicans white-opaque phenotypic switch.

scholarly journals High-throughput single-cell transcriptomics reveals the female germline differentiation trajectory in Arabidopsis thaliana

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhimin Hou ◽  
Yanhui Liu ◽  
Man Zhang ◽  
Lihua Zhao ◽  
Xingyue Jin ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Single Cell ◽  
Cell Fate ◽  
Single Cells ◽  
Expression Patterns ◽  
Cell Types ◽  
Developmental Time ◽  
Developmental Trajectory ◽  
Germline Differentiation ◽  
Female Germline

AbstractFemale germline cells in flowering plants differentiate from somatic cells to produce specialized reproductive organs, called ovules, embedded deep inside the flowers. We investigated the molecular basis of this distinctive developmental program by performing single-cell RNA sequencing (scRNA-seq) of 16,872 single cells of Arabidopsis thaliana ovule primordia at three developmental time points during female germline differentiation. This allowed us to identify the characteristic expression patterns of the main cell types, including the female germline and its surrounding nucellus. We then reconstructed the continuous trajectory of female germline differentiation and observed dynamic waves of gene expression along the developmental trajectory. A focused analysis revealed transcriptional cascades and identified key transcriptional factors that showed distinct expression patterns along the germline differentiation trajectory. Our study provides a valuable reference dataset of the transcriptional process during female germline differentiation at single-cell resolution, shedding light on the mechanisms underlying germline cell fate determination.

Cell contact induces multiple types of electrical excitability from ascidian two-cell embryos that are cleavage arrested and contain all cell fate determinants

2007 ◽  
Vol 293 (5) ◽  
pp. R1976-R1996
Author(s):  
Motoko Tanaka-Kunishima ◽  
Kunitaro Takahashi ◽  
Fumiyuki Watanabe
Keyword(s):  
Stem Cells ◽  
Cell Fate ◽  
Single Cells ◽  
Muscle Cells ◽  
Cell Types ◽  
Specific Cell ◽  
Cell Type ◽  
Cell Pair ◽  
Fate Determinants ◽  
Cell Fate Determinants

Ascidian early embryonic cells undergo cell differentiation without cell cleavage, thus enabling mixture of cell fate determinants in single cells, which will not be possible in mammalian systems. Either cell in a two-cell embryo (2C cell) has multiple fates and develops into any cell types in a tadpole. To find the condition for controlled induction of a specific cell type, cleavage-arrested cell triplets were prepared in various combinations. They were 2C cells in contact with a pair of anterior neuroectoderm cells from eight-cell embryos (2C-aa triplet), with a pair of presumptive notochordal neural cells (2C-AA triplet), with a pair of presumptive posterior epidermal cells (2C-bb triplet), and with a pair of presumptive muscle cells (2C-BB triplet). The fate of the 2C cell was electrophysiologically identified. When two-cell embryos had been fertilized 3 h later than eight-cell embryos and triplets were formed, the 2C cells became either anterior-neuronal, posterior-neuronal or muscle cells, depending on the cell type of the contacting cell pair. When two-cell embryos had been fertilized earlier than eight-cell embryos, most 2C cells became epidermal. When two- and eight-cell embryos had been simultaneously fertilized, the 2C cells became any one of three cell types described above or the epidermal cell type. Differentiation of the ascidian 2C cell into major cell types was reproducibly induced by selecting the type of contacting cell pair and the developmental time difference between the contacting cell pair and 2C cell. We discuss similarities between cleavage-arrested 2C cells and vertebrate embryonic stem cells and propose the ascidian 2C cell as a simple model for toti-potent stem cells.

scholarly journals CD8 single-cell gene coexpression reveals three different effector types present at distinct phases of the immune response

2007 ◽  
Vol 204 (5) ◽  
pp. 1193-1205 ◽  
Author(s):  
António Peixoto ◽  
César Evaristo ◽  
Ivana Munitic ◽  
Marta Monteiro ◽  
Alain Charbit ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Cd8 T Cells ◽  
Cytotoxic T Cells ◽  
Single Cells ◽  
Cell Types ◽  
Primary Response ◽  
Gene Coexpression

To study in vivo CD8 T cell differentiation, we quantified the coexpression of multiple genes in single cells throughout immune responses. After in vitro activation, CD8 T cells rapidly express effector molecules and cease their expression when the antigen is removed. Gene behavior after in vivo activation, in contrast, was quite heterogeneous. Different mRNAs were induced at very different time points of the response, were transcribed during different time periods, and could decline or persist independently of the antigen load. Consequently, distinct gene coexpression patterns/different cell types were generated at the various phases of the immune responses. During primary stimulation, inflammatory molecules were induced and down-regulated shortly after activation, generating early cells that only mediated inflammation. Cytotoxic T cells were generated at the peak of the primary response, when individual cells simultaneously expressed multiple killer molecules, whereas memory cells lost killer capacity because they no longer coexpressed killer genes. Surprisingly, during secondary responses gene transcription became permanent. Secondary cells recovered after antigen elimination were more efficient killers than cytotoxic T cells present at the peak of the primary response. Thus, primary responses produced two transient effector types. However, after boosting, CD8 T cells differentiate into long-lived killer cells that persist in vivo in the absence of antigen.

scholarly journals The neural crest stem cells: control of neural crest cell fate and plasticity by endothelin-3

2001 ◽  
Vol 73 (4) ◽  
pp. 533-545 ◽  
Author(s):  
ELISABETH DUPIN ◽  
CARLA REAL ◽  
NICOLE LeDOUARIN
Keyword(s):  
Stem Cells ◽  
Neural Crest ◽  
Cell Fate ◽  
Neural Crest Cell ◽  
Cell Types ◽  
The Body ◽  
Neural Crest Stem Cells ◽  
Environmental Signals

How the considerable diversity of neural crest (NC)-derived cell types arises in the vertebrate embryo has long been a key question in developmental biology. The pluripotency and plasticity of differentiation of the NC cell population has been fully documented and it is well-established that environmental cues play an important role in patterning the NC derivatives throughout the body. Over the past decade, in vivo and in vitro cellular approaches have unravelled the differentiation potentialities of single NC cells and led to the discovery of NC stem cells. Although it is clear that the final fate of individual cells is in agreement with their final position within the embryo, it has to be stressed that the NC cells that reach target sites are pluripotent and further restrictions occur only late in development. It is therefore a heterogenous collection of cells that is submitted to local environmental signals in the various NC-derived structures. Several factors were thus identified which favor the development of subsets of NC-derived cells in vitro. Moreover, the strategy of gene targeting in mouse has led at identifying new molecules able to control one or several aspects of NC cell differentiation in vivo. Endothelin peptides (and endothelin receptors) are among those. The conjunction of recent data obtained in mouse and avian embryos and reviewed here contributes to a better understanding of the action of the endothelin signaling pathway in the emergence and stability of NC-derived cell phenotypes.

scholarly journals Integration of spatial and single-cell transcriptomic data elucidates mouse organogenesis

2021 ◽  
Author(s):  
T. Lohoff ◽  
S. Ghazanfar ◽  
A. Missarova ◽  
N. Koulena ◽  
N. Pierson ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Fate ◽  
Target Genes ◽  
Single Cells ◽  
Cell Types ◽  
Spatial Context ◽  
Cell Fate Decisions ◽  
Spatially Resolved ◽  
Regulatory Processes ◽  
Cell Transcriptome

AbstractMolecular profiling of single cells has advanced our knowledge of the molecular basis of development. However, current approaches mostly rely on dissociating cells from tissues, thereby losing the crucial spatial context of regulatory processes. Here, we apply an image-based single-cell transcriptomics method, sequential fluorescence in situ hybridization (seqFISH), to detect mRNAs for 387 target genes in tissue sections of mouse embryos at the 8–12 somite stage. By integrating spatial context and multiplexed transcriptional measurements with two single-cell transcriptome atlases, we characterize cell types across the embryo and demonstrate that spatially resolved expression of genes not profiled by seqFISH can be imputed. We use this high-resolution spatial map to characterize fundamental steps in the patterning of the midbrain–hindbrain boundary (MHB) and the developing gut tube. We uncover axes of cell differentiation that are not apparent from single-cell RNA-sequencing (scRNA-seq) data, such as early dorsal–ventral separation of esophageal and tracheal progenitor populations in the gut tube. Our method provides an approach for studying cell fate decisions in complex tissues and development.

scholarly journals Analysis of HIV Reservoirs in Cellular Conjugates from Peripheral Blood

2021 ◽  
Author(s):  
Liliana Pérez ◽  
Daniel Crespo-Vélez ◽  
Max Lee ◽  
Saami Zakaria ◽  
April Poole ◽  
...  
Keyword(s):  
T Cells ◽  
Dna Sequences ◽  
Cd4 T Cells ◽  
Ex Vivo ◽  
Single Cells ◽  
Cell Types ◽  
Hiv Dna ◽  
Infected Cells ◽  
Hiv Controllers

AbstractDefining distinctive attributes of HIV-infected cells will inform development of HIV cure-directed therapies. Prior ex vivo studies of blood and tissue have suggested that some HIV-infected CD4 T cells are found in conjugates with other cell types. Here, we analyzed levels and sequences of HIV nucleic acids in sorted cellular conjugates from PBMC. Compared to single CD4 T cells, conjugates containing CD4 T cells showed no enrichment for HIV DNA or RNA. However, in several HIV controllers, HIV DNA sequences from sorted conjugates were enriched for sequences closely related to plasma viruses. In ART-treated people, although subgenomic HIV DNA sequences in sorted conjugates and single cells were genetically intermingled, intact proviruses were more frequent in whole blood cells than in magnetically-purified CD4 T cells. We conclude that some HIV-infected cells have attributes that predict preferential loss during sample processing, and that may also reflect vulnerability to therapeutic targeting in vivo.

scholarly journals A cell atlas of the adult Drosophila midgut

2018 ◽  
Author(s):  
Ruei-Jiun Hung ◽  
Yanhui Hu ◽  
Rory Kirchner ◽  
Fangge Li ◽  
Chiwei Xu ◽  
...  
Keyword(s):  
Cell Fate ◽  
Single Cells ◽  
Enrichment Analysis ◽  
Cell Types ◽  
Gene Set Enrichment Analysis ◽  
Web Based ◽  
Molecular Features ◽  
Gut Hormone ◽  
A Cell ◽  
Fate Decision

AbstractStudies of the adult Drosophila midgut have provided a number of insights on cell type diversity, stem cell regeneration, tissue homeostasis and cell fate decision. Advances in single-cell RNA sequencing (scRNA-seq) provide opportunities to identify new cell types and molecular features. We used inDrop to characterize the transcriptome of midgut epithelial cells and identified 12 distinct clusters representing intestinal stem cells (ISCs), enteroblasts (EBs), enteroendocrine cells (EEs), enterocytes (ECs) from different regions, and cardia. This unbiased approach recovered 90% of the known ISCs/EBs markers, highlighting the high quality of the dataset. Gene set enrichment analysis in conjunction with electron micrographs revealed that ISCs are enriched in free ribosomes and possess mitochondria with fewer cristae. We demonstrate that a subset of EEs in the middle region of the midgut expresses the progenitor marker esg and that individual EEs are capable of expressing up to 4 different gut hormone peptides. We also show that the transcription factor klumpfuss (klu) is expressed in EBs and functions to suppress EE formation. Lastly, we provide a web-based resource for visualization of gene expression in single cells. Altogether, our study provides a comprehensive resource for addressing novel functions of genes in the midgut epithelium.

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