Utilizing Split Fluorescent Proteins to Visualize Binary Cell Fate Decisions

2021 ◽  
Author(s):  
Setu Mehta
Keyword(s):  
Embryonic Development ◽  
Cell Fate ◽  
Protein Interactions ◽  
Fluorescent Proteins ◽  
Protein Protein Interactions ◽  
Temporal Expression ◽  
Cell Fate Decisions ◽  
Cellular Decision Making ◽  
Decision Making Processes ◽  
Intimate Knowledge

Binary cell fate decisions serve at a cornerstone of cellular decision-making processes during embryonic development. Understanding and studying these decisions require an intimate knowledge of the spatial and temporal expression dynamics of critical genes. Split fluorescent proteins (sFP) can serve as a novel tool to study these binary cell fate decisions, with unique applications such as the potential to amplify weak genetic signals. Ultimately, sFPs can be utilized to revolutionize the study of protein-protein interactions during embryonic development and beyond.

Mitosis in Drosophila

1989 ◽  
Vol 92 (2) ◽  
pp. 137-146 ◽  
Author(s):  
D.M. Glover
Keyword(s):  
Genetic Analysis ◽  
Embryonic Development ◽  
Protein Interactions ◽  
Dynamic Process ◽  
Early Embryogenesis ◽  
Female Sterility ◽  
Protein Protein Interactions ◽  
Stages Of Development ◽  
Cell Cycles

Drosophila is an attractive organism in which to study both the rapid rounds of mitosis typical of embryonic development in many species, and the longer cell cycles of diploid tissues later in development. Mutations in genes essential for mitosis in Drosophila may result in lethality in late embryonic, larval or pupal stages of development. In addition, mutations in many genes required for the nuclear divisions of early embryogenesis have been found in screens for female sterility. The mitotic mutations have phenotypes indicative of lesions at a variety of mitotic stages. A combined molecular and genetic analysis of these genes has the potential to unravel the complex set of protein-protein interactions that occur in this dynamic process.

scholarly journals Mechanism and bottlenecks in strand photodissociation of split green fluorescent proteins (GFPs)

2017 ◽  
Vol 114 (11) ◽  
pp. E2146-E2155 ◽  
Author(s):  
Chi-Yun Lin ◽  
Johan Both ◽  
Keunbong Do ◽  
Steven G. Boxer
Keyword(s):  
Quantum Yield ◽  
Protein Interactions ◽  
Fluorescent Proteins ◽  
Point Mutations ◽  
Photoactive Yellow Protein ◽  
Green Fluorescent Proteins ◽  
Protein Protein Interactions ◽  
Low Efficiency ◽  
Green Fluorescent ◽  
Rate Limiting

Split GFPs have been widely applied for monitoring protein–protein interactions by expressing GFPs as two or more constituent parts linked to separate proteins that only fluoresce on complementing with one another. Although this complementation is typically irreversible, it has been shown previously that light accelerates dissociation of a noncovalently attached β-strand from a circularly permuted split GFP, allowing the interaction to be reversible. Reversible complementation is desirable, but photodissociation has too low of an efficiency (quantum yield <1%) to be useful as an optogenetic tool. Understanding the physical origins of this low efficiency can provide strategies to improve it. We elucidated the mechanism of strand photodissociation by measuring the dependence of its rate on light intensity and point mutations. The results show that strand photodissociation is a two-step process involving light-activated cis-trans isomerization of the chromophore followed by light-independent strand dissociation. The dependence of the rate on temperature was then used to establish a potential energy surface (PES) diagram along the photodissociation reaction coordinate. The resulting energetics–function model reveals the rate-limiting process to be the transition from the electronic excited-state to the ground-state PES accompanying cis-trans isomerization. Comparisons between split GFPs and other photosensory proteins, like photoactive yellow protein and rhodopsin, provide potential strategies for improving the photodissociation quantum yield.

scholarly journals Analysis of IFITM-IFITM Interactions by a Flow Cytometry-Based FRET Assay

2019 ◽  
Vol 20 (16) ◽  
pp. 3859 ◽  
Author(s):  
Michael Winkler ◽  
Florian Wrensch ◽  
Pascale Bosch ◽  
Maike Knoth ◽  
Michael Schindler ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Protein Interactions ◽  
Viral Entry ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Protein Protein Interactions

The interferon-induced transmembrane proteins 1–3 (IFITM1–3) inhibit host cell entry of several viruses. However, it is incompletely understood how IFITM1–3 exert antiviral activity. Two phenylalanine residues, F75 and F78, within the intramembrane domain 1 (IM1) were previously shown to be required for IFITM3/IFITM3 interactions and for inhibition of viral entry, suggesting that IFITM/IFITM interactions might be pivotal to antiviral activity. Here, we employed a fluorescence resonance energy transfer (FRET) assay to analyze IFITM/IFITM interactions. For assay calibration, we equipped two cytosolic, non-interacting proteins, super yellow fluorescent protein (SYFP) and super cyan fluorescent protein (SCFP), with signals that target proteins to membrane rafts and also analyzed a SCFP-SYFP fusion protein. This strategy allowed us to discriminate background signals resulting from colocalization of proteins at membrane subdomains from signals elicited by protein–protein interactions. Coexpression of IFITM1–3 and IFITM5 fused to fluorescent proteins elicited strong FRET signals, and mutation of F75 and F78 in IFITM3 (mutant IFITM3-FF) abrogated antiviral activity, as expected, but did not alter cellular localization and FRET signals. Moreover, IFITM3-FF co-immunoprecipitated efficiently with wild type (wt) IFITM3, lending further support to the finding that lack of antiviral activity of IFITM3-FF was not due to altered membrane targeting or abrogated IFITM3-IFITM3 interactions. Collectively, we report an assay that allows quantifying IFITM/IFITM interactions. Moreover, we confirm residues F75 and F78 as critical for antiviral activity but also show that these residues are dispensable for IFITM3 membrane localization and IFITM3/IFITM3 interactions.

scholarly journals Distinct p53 acetylation cassettes differentially influence gene-expression patterns and cell fate

2006 ◽  
Vol 173 (4) ◽  
pp. 533-544 ◽  
Author(s):  
Chad D. Knights ◽  
Jason Catania ◽  
Simone Di Giovanni ◽  
Selen Muratoglu ◽  
Ricardo Perez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Protein Interactions ◽  
Posttranslational Modifications ◽  
Biological Activities ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Gene Expression Profiles ◽  
P53 Gene ◽  
Protein Protein Interactions

The activity of the p53 gene product is regulated by a plethora of posttranslational modifications. An open question is whether such posttranslational changes act redundantly or dependently upon one another. We show that a functional interference between specific acetylated and phosphorylated residues of p53 influences cell fate. Acetylation of lysine 320 (K320) prevents phosphorylation of crucial serines in the NH2-terminal region of p53; only allows activation of genes containing high-affinity p53 binding sites, such as p21/WAF; and promotes cell survival after DNA damage. In contrast, acetylation of K373 leads to hyperphosphorylation of p53 NH2-terminal residues and enhances the interaction with promoters for which p53 possesses low DNA binding affinity, such as those contained in proapoptotic genes, leading to cell death. Further, acetylation of each of these two lysine clusters differentially regulates the interaction of p53 with coactivators and corepressors and produces distinct gene-expression profiles. By analogy with the “histone code” hypothesis, we propose that the multiple biological activities of p53 are orchestrated and deciphered by different “p53 cassettes,” each containing combination patterns of posttranslational modifications and protein–protein interactions.

scholarly journals MTG16 (CBFA2T3) represses E protein-dependent transcription to regulate colonic secretory cell differentiation, epithelial regeneration, and tumorigenesis

2021 ◽  
Author(s):  
Rachel E. Brown ◽  
Justin Jacobse ◽  
Shruti A. Anant ◽  
Koral M. Blunt ◽  
Bob Chen ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Mouse Model ◽  
Cell Fate ◽  
Protein Interactions ◽  
Protein Function ◽  
Colonic Epithelium ◽  
E Proteins ◽  
Cell Fate Decisions ◽  
Epithelial Regeneration ◽  
E Protein

Aberrant epithelial differentiation and regeneration pathways contribute to colon pathologies including inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). MTG16 (also known as CBFA2T3) is a transcriptional corepressor expressed in the colonic epithelium. MTG16 interaction partners include E box-binding basic helix-loop-helix transcription factors (E proteins). MTG16-deficient mice exhibit worse colitis and increased tumor burden in inflammatory carcinogenesis. In this study, we sought to understand the role of MTG16 in colonic epithelial homeostasis and the mechanisms by which MTG16 protects the epithelium in colitis and CAC. We demonstrated that MTG16 deficiency enabled enteroendocrine cell differentiation from secretory precursor cells at the expense of goblet cells. Transcriptomic analysis implicated dysregulated E protein function in MTG16-deficient colon crypts. Using a novel mouse model with a point mutation that disrupts MTG16:E protein complex formation (Mtg16P209T), we established that enteroendocrine:goblet cell balance was dependent on MTG16:E protein interactions and that the shift in lineage allocation was associated with enhanced expression of Neurog3, the central driver of enteroendocrine lineage specification. Furthermore, Mtg16 was upregulated in the previously described Ascl2+, de-differentiating cells that replenish the stem cell compartment in response to colon injury. Mtg16 expression was also increased in dextran sulfate sodium (DSS)-treated mouse colon crypts and in IBD patients compared to unaffected controls. We determined that the effects of MTG16 in regeneration are also dependent on its repression of E proteins, as the colonic epithelium failed to regenerate following DSS-induced injury in our novel mutant mouse model. Finally, we revealed that uncoupling MTG16:E protein interactions contributes to the enhanced tumorigenicity in Mtg16-/- colon in the azoxymethane(AOM)/DSS-induced model of CAC. Collectively, our results demonstrate that MTG16, via its repression of E protein targets, is a key regulator of cell fate decisions during colonic differentiation and regeneration.

scholarly journals Redesign of Genetically Encoded Biosensors for Monitoring Mitochondrial Redox Status in a Broad Range of Model Eukaryotes

2013 ◽  
Vol 19 (3) ◽  
pp. 379-386 ◽  
Author(s):  
Simone C. Albrecht ◽  
Mirko C. Sobotta ◽  
Daniela Bausewein ◽  
Isabel Aller ◽  
Rüdiger Hell ◽  
...  
Keyword(s):  
Cell Fate ◽  
Fluorescent Proteins ◽  
Redox Homeostasis ◽  
Redox Status ◽  
Model Organisms ◽  
Green Fluorescent Proteins ◽  
Cell Fate Decisions ◽  
Major Interest ◽  
Green Fluorescent

The development of genetically encoded redox biosensors has paved the way toward chemically specific, quantitative, dynamic, and compartment-specific redox measurements in cells and organisms. In particular, redox-sensitive green fluorescent proteins (roGFPs) have attracted major interest as tools to monitor biological redox changes in real time and in vivo. Most recently, the engineering of a redox relay that combines glutaredoxin (Grx) with roGFP2 as a translational fusion (Grx1-roGFP2) led to a biosensor for the glutathione redox potential ( EGSH). The expression of this probe in mitochondria is of particular interest as mitochondria are the major source of oxidants, and their redox status is closely connected to cell fate decisions. While Grx1-roGFP2 can be expressed in mammalian mitochondria, it fails to enter mitochondria in various nonmammalian model organisms. Here we report that inversion of domain order from Grx1-roGFP2 to roGFP2-Grx1 yields a biosensor with perfect mitochondrial targeting while fully maintaining its biosensor capabilities. The redesigned probe thus allows extending in vivo observations of mitochondrial redox homeostasis to important nonmammalian model organisms, particularly plants and insects.

scholarly journals Inhibition of β-catenin–TCF1 interaction delays differentiation of mouse embryonic stem cells

2015 ◽  
Vol 211 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Sujash S. Chatterjee ◽  
Abil Saj ◽  
Tenzin Gocha ◽  
Matthew Murphy ◽  
Foster C. Gonsalves ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Cell Fate ◽  
Protein Interactions ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells ◽  
Protein Protein Interactions ◽  
Nanog Expression ◽  
Context Specific

The ability of mouse embryonic stem cells (mESCs) to self-renew or differentiate into various cell lineages is regulated by signaling pathways and a core pluripotency transcriptional network (PTN) comprising Nanog, Oct4, and Sox2. The Wnt/β-catenin pathway promotes pluripotency by alleviating T cell factor TCF3-mediated repression of the PTN. However, it has remained unclear how β-catenin’s function as a transcriptional activator with TCF1 influences mESC fate. Here, we show that TCF1-mediated transcription is up-regulated in differentiating mESCs and that chemical inhibition of β-catenin/TCF1 interaction improves long-term self-renewal and enhances functional pluripotency. Genetic loss of TCF1 inhibited differentiation by delaying exit from pluripotency and conferred a transcriptional profile strikingly reminiscent of self-renewing mESCs with high Nanog expression. Together, our data suggest that β-catenin’s function in regulating mESCs is highly context specific and that its interaction with TCF1 promotes differentiation, further highlighting the need for understanding how its individual protein–protein interactions drive stem cell fate.

scholarly journals Strategies to improve the fluorescent signal of the tripartite sfGFP system

2020 ◽  
Vol 52 (9) ◽  
pp. 998-1006
Author(s):  
Jing Shen ◽  
Wenlu Zhang ◽  
Chunyang Gan ◽  
Xiafei Wei ◽  
Jie Li ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Bimolecular Fluorescence Complementation ◽  
Fluorescence Signal ◽  
Recovery Efficiency ◽  
Good Recovery ◽  
Protein Protein Interactions ◽  
Bifc Assay ◽  
Green Fluorescent

Abstract Bimolecular fluorescence complementation (BiFC) is a popular method used to detect protein–protein interactions. For a BiFC assay, a fluorescent protein is usually split into two parts, and the fluorescence is recovered upon the interaction between the fused proteins of interest. As an elegant extension of BiFC, a tripartite superfold green fluorescent protein (sfGFP) system that has the advantages of low background fluorescence and small fusion tag size has been developed. However, the tripartite system exhibits a low fluorescence signal in some cases. To address this problem, we proposed to increase the affinity between the two parts, G1–9 and G11, of the tripartite system by adding affinity pairs. Among the three affinity pairs tested, LgBiT-HiBiT improved both the signal and signal-to-noise (S/N) ratio to the greatest extent. More strikingly, the direct covalent fusion of G11 to G1–9, which converted the tripartite system into a new bipartite system, enhanced the S/N ratio from 20 to 146, which is superior to the bipartite sfGFP system split at 157/158 or 173/174. Our results implied that the 10th β-strand of sfGFP has a low affinity and a good recovery efficiency to construct a robust BiFC system, and this concept might be applied to other fluorescent proteins with similar structure to construct new BiFC systems.

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