Single-cell protein analysis reveals metastable states during the transition to a sensory organ fate

2021 ◽  
Author(s):  
Ritika Giri ◽  
Shannon C Brady ◽  
Richard William Carthew
Keyword(s):  
Cell Fate ◽  
Single Cell Protein ◽  
Sensory Organ ◽  
Bistable System ◽  
Cell Protein ◽  
Organ Differentiation ◽  
Cell Fate Decisions ◽  
Number Variation ◽  
Drosophila Cells ◽  
Protein Number

Cell fate decisions can be envisioned as bifurcating dynamical systems, and the decision that Drosophila cells make to undergo sensory organ differentiation has been sucessfully described as such. We have extended these studies by focusing on the Senseless protein, which orchestrates the sensory fate transition. Wing cells contain intermediate Senseless numbers prior to their fate transition, after which they express much greater numbers of Senseless molecules as they differentiate. However, the dynamics are not consistent with it being a simple bistable system. Cells with intermediate Senseless are best modeled as residing in four discrete states, each with a distinct protein number and occupying a specific region of the tissue. Although the four states are stable over time, the number of molecules in each state vary with time. Remarkably, the fold-change in molecule number between adjacent states is invariant and robust to absolute protein number variation. Thus, cells transitioning to sensory fates exhibit metastability with relativistic properties.

scholarly journals Drosophila Notch receptor activity suppresses Hairless function during adult external sensory organ development.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1491-1505
Author(s):  
D F Lyman ◽  
B Yedvobnick
Keyword(s):  
Cell Fate ◽  
Daughter Cell ◽  
Notch Receptor ◽  
Sensory Organ ◽  
Cell Fates ◽  
Gain Of Function ◽  
Over Expression ◽  
Cell Fate Decisions ◽  
Synergistic Enhancement ◽  
Conditional Expression

Abstract The neurogenic Notch locus of Drosophila encodes a receptor necessary for cell fate decisions within equivalence groups, such as proneural clusters. Specification of alternate fates within clusters results from inhibitory communication among cells having comparable neural fate potential. Genetically, Hairless (H) acts as an antagonist of most neurogenic genes and may insulate neural precursor cells from inhibition. H function is required for commitment to the bristle sensory organ precursor (SOP) cell fate and for daughter cell fates. Using Notch gain-of-function alleles and conditional expression of an activated Notch transgene, we show that enhanced signaling produces H-like loss-of-function phenotypes by suppressing bristle SOP cell specification or by causing an H-like transformation of sensillum daughter cell fates. Furthermore, adults carrying Notch gain of function and H alleles exhibit synergistic enhancement of mutant phenotypes. Over-expression of an H+ transgene product suppressed virtually all phenotypes generated by Notch gain-of-function genotypes. Phenotypes resulting from over-expression of the H+ transgene were blocked by the Notch gain-of-function products, indicating a balance between Notch and H activity. The results suggest that H insulates SOP cells from inhibition and indicate that H activity is suppressed by Notch signaling.

Role of Notch and achaete-scute complex in the expression of Enhancer of split bHLH proteins

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3745-3752 ◽  
Author(s):  
V. Jennings ◽  
J. de Celis ◽  
C. Delidakis ◽  
A. Preiss ◽  
S. Bray
Keyword(s):  
Cell Fate ◽  
Notch Pathway ◽  
Interaction Mechanism ◽  
Cell Interaction ◽  
Precursor Cell ◽  
Notch Receptor ◽  
Sensory Organ ◽  
Cell Fate Decisions ◽  
Sensory Organ Precursor ◽  
Enhancer Of Split

The proteins encoded by Notch and the Enhancer of split complex are components of a cell-cell interaction mechanism which is important in many cell fate decisions throughout development. One such decision is the formation of the sensory organ precursor cell during the development of the peripheral nervous system in Drosophila. Cells acquire the potential to be neural through the expression of the proneural genes, and the Notch pathway is required to limit neural fate to a single cell from a proneural cluster. However, despite extensive analysis, the precise pathways linking the proneural with Notch and Enhancer of split gene functions remain obscure. For example, it has been suggested that achaete-scute complex proteins directly activate Enhancer of split genes leaving the action of Notch in the pathway unclear. Using monoclonal antibodies that recognise products of the Enhancer of split complex, we show that these proteins accumulate in the cells surrounding the developing sensory organ precursor cell and that their expression is dependent on the activity of Notch and does not directly correlate with expression of Achaete. We further clarify the pathway by showing that ubiquitous expression of an activated Notch receptor leads to widespread accumulation of Enhancer of split proteins even in the absence of achaete-scute complex proteins. Thus Enhancer of split protein expression in response to Notch activity does not require achaete-scute complex proteins.

scholarly journals Screening for gene expression fluctuations reveals latency-promoting agents of HIV

2021 ◽  
Vol 118 (11) ◽  
pp. e2012191118
Author(s):  
Yiyang Lu ◽  
Kathrin Bohn-Wippert ◽  
Patrick J. Pazerunas ◽  
Jennifer M. Moy ◽  
Harpal Singh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Thioredoxin Reductase ◽  
Time Lapse ◽  
Redox Balance ◽  
Single Cell Protein ◽  
Host Cells ◽  
Cell Protein ◽  
Latent Reservoir ◽  
Major Barrier

Upon treatment removal, spontaneous reactivation of latently infected T cells remains a major barrier toward curing HIV. Therapies that reactivate and clear the latent reservoir are only partially effective, while latency-promoting agents (LPAs) used to suppress reactivation and stabilize latency are understudied and lack diversity in their mechanisms of action. Here, we identify additional LPAs using a screen for gene-expression fluctuations (or “noise”) that drive cell-fate specification and control HIV reactivation from latency. Single-cell protein dynamics of a minimal HIV gene circuit were monitored with time-lapse fluorescence microscopy. We screened 1,806 drugs, out of which 279 modulate noise magnitude or half autocorrelation time. Next, we tested the strongest noise modulators in a Jurkat T cell latency model and discovered three LPAs that would be overlooked by quantifying their mean expression levels alone. The LPAs reduced reactivation of latency in both Jurkat and primary cell models when challenged by synergistic and potent combinations of HIV activators. The two strongest LPAs, NSC 401005 and NSC 400938, are structurally and functionally related to inhibitors of thioredoxin reductase, a protein involved in maintaining redox balance in host cells. Experiments with multiple functional analogs revealed two additional LPAs, PX12 and tiopronin, and suggest a potential LPA family, within which some are commercially available and Food and Drug Administration–approved. The LPAs presented here may provide new strategies to complement antiretroviral treatments. Screening for gene expression noise holds the potential for drug discovery in other diseases.

scholarly journals The novel lncRNA lnc-NR2F1 is pro-neurogenic and mutated in human neurodevelopmental disorders

2018 ◽  
Author(s):  
Cheen Euong Ang ◽  
Qing Ma ◽  
Orly L. Wapinski ◽  
Shenghua Fan ◽  
Ryan A. Flynn ◽  
...  
Keyword(s):  
Cell Fate ◽  
Human Genetics ◽  
Neuronal Cell ◽  
Chromosomal Translocation ◽  
Autism Spectrum ◽  
Cell Fate Decisions ◽  
Number Variation ◽  
Neuronal Genes ◽  
Neuronal Lineage ◽  
Candidate Loci

AbstractLong noncoding RNAs (lncRNAs) have been shown to act as important cell biological regulators including cell fate decisions but are often ignored in human genetics. Combining differential lncRNA expression during neuronal lineage induction with copy number variation morbidity maps of a cohort of children with autism spectrum disorder/intellectual disability versus healthy controls revealed focal genomic mutations affecting several lncRNA candidate loci. Here we find that a t(5:12) chromosomal translocation in a family manifesting neurodevelopmental symptoms disrupts specifically lnc-NR2F1. We further show that lnc-NR2F1 is an evolutionarily conserved lncRNA functionally enhances induced neuronal cell maturation and directly occupies and regulates transcription of neuronal genes including autism-associated genes. Thus, integrating human genetics and functional testing in neuronal lineage induction is a promising approach for discovering candidate lncRNAs involved in neurodevelopmental diseases.

scholarly journals The novel lncRNA lnc-NR2F1 is pro-neurogenic and mutated in human neurodevelopmental disorders

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Cheen Euong Ang ◽  
Qing Ma ◽  
Orly L Wapinski ◽  
ShengHua Fan ◽  
Ryan A Flynn ◽  
...  
Keyword(s):  
Cell Fate ◽  
Human Genetics ◽  
Neuronal Cell ◽  
Chromosomal Translocation ◽  
Autism Spectrum ◽  
Cell Fate Decisions ◽  
Number Variation ◽  
Neuronal Genes ◽  
Neuronal Lineage ◽  
Candidate Loci

Long noncoding RNAs (lncRNAs) have been shown to act as important cell biological regulators including cell fate decisions but are often ignored in human genetics. Combining differential lncRNA expression during neuronal lineage induction with copy number variation morbidity maps of a cohort of children with autism spectrum disorder/intellectual disability versus healthy controls revealed focal genomic mutations affecting several lncRNA candidate loci. Here we find that a t(5:12) chromosomal translocation in a family manifesting neurodevelopmental symptoms disrupts specifically lnc-NR2F1. We further show that lnc-NR2F1 is an evolutionarily conserved lncRNA functionally enhances induced neuronal cell maturation and directly occupies and regulates transcription of neuronal genes including autism-associated genes. Thus, integrating human genetics and functional testing in neuronal lineage induction is a promising approach for discovering candidate lncRNAs involved in neurodevelopmental diseases.

scholarly journals Single cell protein analysis for systems biology

2018 ◽  
Vol 62 (4) ◽  
pp. 595-605 ◽  
Author(s):  
Ezra Levy ◽  
Nikolai Slavov
Keyword(s):  
Systems Biology ◽  
Single Cell ◽  
Cell Fate ◽  
Fluorescent Proteins ◽  
Single Cells ◽  
Protein Analysis ◽  
Single Cell Protein ◽  
Cell Protein ◽  
Protein Levels ◽  
Trade Offs

The cellular abundance of proteins can vary even between isogenic single cells. This variability between single-cell protein levels can have regulatory roles, such as controlling cell fate during apoptosis induction or the proliferation/quiescence decision. Here, we review examples connecting protein levels and their dynamics in single cells to cellular functions. Such findings were made possible by the introduction of antibodies, and subsequently fluorescent proteins, for tracking protein levels in single cells. However, in heterogeneous cell populations, such as tumors or differentiating stem cells, cellular decisions are controlled by hundreds, even thousands of proteins acting in concert. Characterizing such complex systems demands measurements of thousands of proteins across thousands of single cells. This demand has inspired the development of new methods for single-cell protein analysis, and we discuss their trade-offs, with an emphasis on their specificity and coverage. We finish by highlighting the potential of emerging mass-spec methods to enable systems-level measurement of single-cell proteomes with unprecedented coverage and specificity. Combining such methods with methods for quantitating the transcriptomes and metabolomes of single cells will provide essential data for advancing quantitative systems biology.

scholarly journals Bazooka/Par3 cooperates with Sanpodo for the assembly of Notch signaling clusters following asymmetric division of Drosophila sensory organ precursor cells

2021 ◽  
Author(s):  
Elise Houssin ◽  
Mathieu Pinot ◽  
Karen Bellec ◽  
Roland Le Borgne
Keyword(s):  
Plasma Membrane ◽  
Notch Signaling ◽  
Cell Fate ◽  
Sensory Organ ◽  
Cell Fate Decisions ◽  
Daughter Cells ◽  
Delta Activity ◽  
Multiple Cell ◽  
Sensory Organ Precursor ◽  
Fate Decision

SummaryIn multiple cell lineages, Delta-Notch signaling regulates cell fate decisions owing to unidirectional signaling between daughter cells. In Drosophila pupal sensory organ lineage, Notch regulates pIIa/pIIb fate decision at cytokinesis. Notch and Delta that localize apically and basally at the pIIa-pIIb interface, are expressed at low levels and their residence time at the plasma membrane is in the order of the minute. How Delta can effectively interact with Notch to trigger signaling from a large plasma membrane remains poorly understood. Here, we report that the signaling interface possesses a unique apicobasal polarity with Par3/Bazooka localizing in the form of nano-clusters at the apical and basal level. Notch is preferentially targeted to the pIIa-pIIb interface where it co-clusters with Bazooka and the Notch cofactor Sanpodo. Clusters whose assembly relies on Bazooka and Sanpodo activities, are also positive for Neuralized, the E3 ligase required for Delta-activity. We propose that the nano-clusters act as snap buttons at the new pIIa-pIIb interface to allow efficient intra-lineage signaling.

Antagonistic activities of Suppressor of Hairless and Hairless control alternative cell fates in the Drosophila adult epidermis

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1433-1441 ◽  
Author(s):  
F. Schweisguth ◽  
J.W. Posakony
Keyword(s):  
Cell Fate ◽  
Imaginal Disc ◽  
Sensory Organ ◽  
Cell Fate Decisions ◽  
Suppressor Of Hairless ◽  
Disc Cells ◽  
Sensory Organ Precursor ◽  
Fate Decision ◽  
Mutant Phenotypes ◽  
Proneural Cluster

Successive alternative cell fate choices in the imaginal disc epithelium lead to the differentiation of a relatively invariant pattern of multicellular adult sensory organs in Drosophila. We show here that the activity of Suppressor of Hairless is required for both the sensory organ precursor (SOP) versus epidermal cell fate decision, and for the trichogen (shaft) versus tormogen (socket) cell fate choice. Complete loss of Suppressor of Hairless function causes most proneural cluster cells to accumulate high levels of the achaete and Delta proteins and to adopt the SOP fate. Late or partial reduction in Suppressor of Hairless activity leads to the apparent transformation of the tormogen (socket) cell into a second trichogen (shaft) cell, producing a ‘double shaft’ phenotype. We find that overexpression of Suppressor of Hairless has the opposite phenotypic effects. SOP determination is prevented by an early excess of Suppressor of Hairless activity, while at a later stage, the trichogen (shaft) cell is transformed into a second tormogen (socket) cell, resulting in ‘double socket’ bristles. We conclude that, for two different cell fate decisions in adult sensory organ development, decreasing or increasing the level of Suppressor of Hairless function confers mutant phenotypes that closely resemble those associated with gain and loss of Hairless activity, respectively. These results, along with the intermediate SOP phenotype observed in Suppressor of Hairless; Hairless double mutant imaginal discs, suggest that the two genes act antagonistically to commit imaginal disc cells stably to alternative fates.

scholarly journals Bazooka/Par3 cooperates with Sanpodo for the assembly of Notch clusters following asymmetric division of Drosophila sensory organ precursor cells

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Elise Houssin ◽  
Mathieu Pinot ◽  
Karen Bellec ◽  
Roland Le Borgne
Keyword(s):  
Plasma Membrane ◽  
Cell Fate ◽  
Sensory Organ ◽  
Membrane Area ◽  
Cell Fate Decisions ◽  
Daughter Cells ◽  
Delta Activity ◽  
Multiple Cell ◽  
Sensory Organ Precursor ◽  
Fate Decision

In multiple cell lineages, Delta-Notch signalling regulates cell fate decisions owing to unidirectional signalling between daughter cells. In Drosophila pupal sensory organ lineage, Notch regulates the intra-lineage pIIa/pIIb fate decision at cytokinesis. Notch and Delta that localise apically and basally at the pIIa-pIIb interface are expressed at low levels and their residence time at the plasma membrane is in the order of minutes. How Delta can effectively interact with Notch to trigger signalling from a large plasma membrane area remains poorly understood. Here, we report that the signalling interface possesses a unique apicobasal polarity with Par3/Bazooka localising in the form of nano-clusters at the apical and basal level. Notch is preferentially targeted to the pIIa-pIIb interface, where it co-clusters with Bazooka and its cofactor Sanpodo. Clusters whose assembly relies on Bazooka and Sanpodo activities are also positive for Neuralized, the E3 ligase required for Delta-activity. We propose that the nano-clusters act as snap buttons at the new pIIa-pIIb interface to allow efficient intra-lineage signalling.

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