Qr: host:"HEK293"
Showing 1 - 25 of 365 results
1.
Optogenetic control of biomolecular organization reveals distinct roles of phase separation in RTK signaling.
Abstract:
Multimerization and phase separation represent two paradigms for organizing receptor tyrosine kinases (RTKs). However, their functional distinctions from the perspective of biomolecular organization remain unclear. Here, we present CORdensate, a light-controllable condensation system combining two synergistic photoactuators: oligomeric Cry2 and heterodimeric LOVpep/ePDZ. Engineering single-chain photoswitches, we achieve four biomolecular organization patterns ranging from monomerization to phase separation. CORdensate exhibits constant assembly and disassembly kinetics. Applying CORdensate to mimic pathogenic RTK granules establishes the role of phase separation in activating ALK and RET. Moreover, assembling ALK and RET through varying organization patterns, we highlight the superior organizational ability of phase separation over multimerization. Additionally, CORdensate-based RTK granules suggest that phase separation broadly and robustly activates RTKs. This study introduces a optogenetic tool for investigating biomolecular condensation.
2.
Rapid Optimization of a Light-Inducible System to Control Mammalian Gene Expression.
Abstract:
Inducible gene expression tools can open novel applications in human health and biotechnology, but current options are often expensive, difficult to reverse, and have undesirable off-target effects. Optogenetic systems use light-responsive proteins to control the activity of regulators such that expression is controlled with the "flip of a switch". This study optimizes a simplified light activated CRISPR effector (2pLACE) system, which provides tunable, reversible, and precise control of mammalian gene expression. The OptoPlate-96 enables high-throughput screening via flow cytometry for single-cell analysis and rapid optimization of 2pLACE. This study demonstrates how to use the 2pLACE system with the OptoPlate-96 in HEK293T cells to identify the optimal component ratios for maximizing dynamic range and to find the blue light intensity response curve. Similar workflows can be developed for other mammalian cells and for other optogenetic systems and wavelengths of light. These advancements enhance the precision, scalability, and adaptability of optogenetic tools for biomanufacturing applications.
3.
Shining light on drug discovery: optogenetic screening for TopBP1 biomolecular condensate inhibitors.
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Morano, L
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Vie, N
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Aissanou, A
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Hodroj, D
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Garambois, V
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Fauvre, A
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Promonet, A
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Egger, T
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Bordignon, B
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Hassen-Khodja, C
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Fiachetti, S
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Basbous, J
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Gongora, C
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Constantinou, A
Abstract:
Human topoisomerase IIβ binding protein 1 (TopBP1) is a scaffold protein involved in DNA replication initiation, DNA repair, transcription regulation, and checkpoint activation. TopBP1 forms nuclear condensates that act as a molecular switch to amplify ATR activity and promote the activation of the checkpoint effector kinase Chk1. In cancer cells, ATR activity is crucial to tolerate the intrinsically high level of DNA lesions and obstacles that block replication fork progression. Thus, ATR inhibitors are currently tested in clinical trials, often in combination with chemotherapy drugs. However, resistance and toxicity are still major issues. The weak interactions that hold TopBP1 condensates together are highly sensitive to changes in the cellular milieu, suggesting that small molecules may alter the formation of TopBP1 condensates. Here, we developed a high-throughput screening system to identify TopBP1 condensation modulators. This system allowed us to identify FDA-approved drugs, including thimerosal and quinacrine, that inhibit TopBP1 condensation and block the activation of ATR/Chk1 signaling. Mechanistically, quinacrine impaired TopBP1's ability to associate with chromatin, thereby interfering with its capacity to form condensates. Furthermore, quinacrine enhanced the therapeutic efficacy of 5-fluorouracil and irinotecan, components of the clinically used FOLFIRI regimen in a mouse model of peritoneal carcinomatosis from colorectal cancer.
4.
Photoswitchable intein for light control of covalent protein binding and cleavage.
Abstract:
Precise control of covalent protein binding and cleavage in mammalian cells is crucial for manipulating cellular processes but remains challenging due to dark background, poor stability, low efficiency, or requirement of unnatural amino acids in current optogenetic tools. We introduce a photoswitchable intein (PS Intein) engineered by allosterically modulating a small autocatalytic gp41-1 intein with tandem Vivid photoreceptor. PS Intein exhibits superior functionality and low background in cells compared to existing tools. PS Intein-based systems enable light-induced covalent binding, cleavage, and release of proteins for regulating gene expression and cell fate. The high responsiveness and ability to integrate multiple inputs allow for intersectional cell targeting using cancer- and tumor microenvironment-specific promoters. PS Intein tolerates various fusions and insertions, facilitating its application in diverse cellular contexts. This versatile technology offers efficient light-controlled protein manipulation, providing a powerful tool for adding functionalities to proteins and precisely controlling protein networks in living cells.
5.
Proximity-specific ribosome profiling reveals the logic of localized mitochondrial translation.
Abstract:
Localized translation broadly enables spatiotemporal control of gene expression. Here, we present LOV-domain-controlled ligase for translation localization (LOCL-TL), an optogenetic approach for monitoring translation with codon resolution at any defined subcellular location under physiological conditions. Application of LOCL-TL to mitochondrially localized translation revealed that ∼20% of human nuclear-encoded mitochondrial genes are translated on the outer mitochondrial membrane (OMM). Mitochondrially translated messages form two classes distinguished by encoded protein length, recruitment mechanism, and cellular function. An evolutionarily ancient mechanism allows nascent chains to drive cotranslational recruitment of long proteins via an unanticipated bipartite targeting signal. Conversely, mRNAs of short proteins, especially eukaryotic-origin electron transport chain (ETC) components, are specifically recruited by the OMM protein A-kinase anchoring protein 1 (AKAP1) in a translation-independent manner that depends on mRNA splicing. AKAP1 loss lowers ETC levels. LOCL-TL thus reveals a hierarchical strategy that enables preferential translation of a subset of proteins on the OMM.
6.
A rapid and efficient red-light-activated Cre recombinase system for genome engineering in mammalian cells and transgenic mice.
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Zhou, Y
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Wei, Y
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Yin, J
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Kong, D
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Li, W
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Wang, X
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Yao, Y
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Huang, Q
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Li, L
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Liu, M
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Qiao, L
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Li, H
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Zhao, J
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Zhong, TP
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Li, D
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Duan, L
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Guan, N
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Ye, H
Abstract:
The Cre-loxP recombination system enables precise genome engineering; however, existing photoactivatable Cre tools suffer from several limitations, including low DNA recombination efficiency, background activation, slow activation kinetics, and poor tissue penetration. Here, we present REDMAPCre, a red-light-controlled split-Cre system based on the ΔPhyA/FHY1 interaction. REDMAPCre enables rapid activation (1-s illumination) and achieves an 85-fold increase in reporter expression over background levels. We demonstrate its efficient regulation of DNA recombination in mammalian cells and mice, as well as its compatibility with other inducible recombinase systems for Boolean logic-gated DNA recombination. Using a single-vector adeno-associated virus delivery system, we successfully induced REDMAPCre-mediated DNA recombination in mice. Furthermore, we generated a REDMAPCre transgenic mouse line and validated its efficient, light-dependent recombination across multiple organs. To explore its functional applications, REDMAPCre transgenic mice were crossed with isogenic Cre-dependent reporter mice, enabling optogenetic induction of insulin resistance and hepatic lipid accumulation via Cre-dependent overexpression of ubiquitin-like with PHD and RING finger domains 1 (UHRF1), as well as targeted cell ablation through diphtheria toxin fragment A expression. Collectively, REDMAPCre provides a powerful tool for achieving remote control of recombination and facilitating functional genetic studies in living systems.
7.
Activation of NF-κB Signaling by Optogenetic Clustering of IKKα and β.
Abstract:
Molecular optogenetics allows the control of molecular signaling pathways in response to light. This enables the analysis of the kinetics of signal activation and propagation in a spatially and temporally resolved manner. A key strategy for such control is the light-inducible clustering of signaling molecules, which leads to their activation and subsequent downstream signaling. In this work, an optogenetic approach is developed for inducing graded clustering of different proteins that are fused to eGFP, a widely used protein tag. To this aim, an eGFP-specific nanobody is fused to Cryptochrome 2 variants engineered for different orders of cluster formation. This is exemplified by clustering eGFP-IKKα and eGFP-IKKβ, thereby achieving potent and reversible activation of NF-κB signaling. It is demonstrated that this approach can activate downstream signaling via the endogenous NF-κB pathway and is thereby capable of activating both an NF-κB-responsive reporter construct as well as endogenous NF-κB-responsive target genes as analyzed by RNA sequencing. The generic design of this system is likely transferable to other signaling pathways to analyze the kinetics of signal activation and propagation.
8.
Chemogenetic and optogenetic strategies for spatiotemporal control of split-enzyme-based calcium recording.
Abstract:
Methods for monitoring physiological changes in cellular Ca2+ levels have been in high demand for their utility in monitoring neuronal signaling. Recently, we introduced SCANR (Split-Tobacco Etch Virus (TEV) protease Calcium-regulated Neuron Recorder), which reports on Ca2+ changes in cells through the binding of calmodulin and M13 to reconstitute an active TEV protease. First-generation SCANR marked all of the Ca2+ spikes that occur throughout the lifetime of the cell, but it did not have a mechanism for controlling the time window in which recording of physiological changes in Ca2+ occurred. Here, we explore both chemical and light-based strategies for controlling the time and place in which Ca2+ recording occurs. We describe the adaptation of six popular chemo- and opto-genetics methods for controlling protein activity and subcellular localization to the SCANR system. We report two successful strategies, one that leverages the LOV-Jα optogenetics system for sterically controlling protein interactions and another that employs chemogenetic manipulation of subcellular protein distribution using the FKBP/FRB rapamycin binding pair.
9.
A versatile anti-CRISPR platform for opto- and chemogenetic control of CRISPR-Cas9 and Cas12 across a wide range of orthologs.
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Brenker, L
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Aschenbrenner, S
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Bubeck, F
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Staykov, K
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Gebhardt, C
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Wolf, B
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Jendrusch, M
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Kröll, AS
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Becker, J
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Ambiel, I
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Fackler, OT
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Grimm, D
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Mathony, J
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Niopek, D
Abstract:
CRISPR-Cas technologies have revolutionized life sciences by enabling programmable genome editing across diverse organisms. Achieving dynamic and precise control over CRISPR-Cas activity with exogenous triggers, such as light or chemical ligands, remains an important need. Existing tools for CRISPR-Cas control are often limited to specific Cas orthologs or selected applications, restricting their versatility. Anti-CRISPR (Acr) proteins are natural inhibitors of CRISPR-Cas systems and provide a flexible regulatory layer but are constitutively active in their native forms. In this study, we built on our previously reported concept for optogenetic CRISPR-Cas control with engineered, light-switchable anti-CRISPR proteins and expanded it from ortholog-specific Acrs towards AcrIIA5 and AcrVA1, broad-spectrum inhibitors of CRISPR-Cas9 and CRISPR-Cas12a, respectively. We then conceived and implemented a novel, chemogenetic anti-CRISPR platform based on engineered, circularly permuted ligand receptor domains, that together respond to six clinically relevant drugs. The resulting toolbox achieves both optogenetic and chemogenetic control of genome editing in human cells with a wide range of CRISPR-Cas effectors, including type II-A and II-C CRISPR-Cas9s, and CRISPR-Cas12a. In sum, this work establishes a versatile platform for the multidimensional control of CRISPR-Cas systems, with immediate applications in basic research and biotechnology, and with the potential for therapeutic use in the future.
10.
A simplified two-plasmid system for orthogonal control of mammalian gene expression using light-activated CRISPR effector.
Abstract:
Optogenetic systems use light-responsive proteins to control gene expression, ion channels, protein localization, and signaling with the "flip of a switch". One such tool is the light activated CRISPR effector (LACE) system. Its ability to regulate gene expression in a tunable, reversible, and spatially resolved manner makes it attractive for many applications. However, LACE relies on delivery of four separate components on individual plasmids, which can limit its use. Here, we optimize LACE to reduce the number of plasmids needed to deliver all four components.
11.
Pharmacological interventions on GSK3β phosphorylation-mediated tau aggregation by modulating phase separation of tau proline-rich domain.
Abstract:
Tau pathological aggregation in neurofibrillary tangles is a hallmark of several neurodegenerative diseases, including Alzheimer's disease. Phase separation is a thermodynamic process that plays an important role in biomolecular membrane-less condensate formation, while abnormal phase separation of tau leads to pathological aggregate formation. However, the detailed molecular mechanism underlying tau condensation remains not fully understood. Moreover, whether condensation-based pharmacological intervention will be helpful for the treatment of tau-associated neurodegenerative diseases remains elusive. Here, we used an optogenetic tool (optoDroplets) in combination with cell biology and pharmacology to explore the contribution of different domains for tau condensation in cells, and we found that proline-rich domain (PRD) phosphorylation, which is mainly regulated by glycogen synthase kinase 3 β (GSK3β), plays important roles for tau condensation. Moreover, phosphorylation of tau PRD regulates its mis-localization on nuclear speckle. Interestingly and importantly, we found that pharmacological inhibition of GSK3β can impede abnormal tau condensation to slow down the tau-associated pathological process.
12.
Potent optogenetic regulation of gene expression in mammalian cells for bioproduction and basic research.
Abstract:
Precise temporal and spatial control of gene expression greatly benefits the study of specific cellular circuits and activities. Compared to chemical inducers, light-dependent control of gene expression by optogenetics achieves a higher spatial and temporal resolution. Beyond basic research, this could also prove decisive for manufacturing difficult-to-express proteins in pharmaceutical bioproduction. However, current optogenetic gene-expression systems limit this application in mammalian cells, as expression levels and the degree of induction upon light stimulation are insufficient. To overcome this limitation, we designed a photoswitch by fusing the blue light-activated light-oxygen-voltage receptor EL222 from Erythrobacter litoralis to the three transcriptional activator domains VP64, p65, and Rta in tandem. The resultant photoswitch, dubbed DEL-VPR, allows up to a 570-fold induction of target gene expression by blue light, thereby achieving expression levels of strong constitutive promoters. Here, we used DEL-VPR to enable light-induced expression of complex monoclonal and bispecific antibodies with reduced byproduct expression and increased yield of functional protein complexes. Our approach offers temporally controlled yet strong gene expression and applies to academic and industrial settings.
13.
An Optical Approach to Modulating Membrane Protein Endocytosis Using a Light-Responsive Tag for Recruiting β-Arrestin.
Abstract:
Membrane receptors, particularly G protein-coupled receptors (GPCRs), are integral to numerous physiological processes. Precise control of the receptor endocytosis is essential for understanding cellular signaling pathways. In this study, we present the development of a broadly applicable optogenetic tool for light-inducible receptor internalization. This system, named E-fragment, leverages the CRY2-CIB photodimerization pair to enable blue-light-dependent recruitment of β-arrestin and subsequent receptor internalization. We showed that the E-fragment system is applicable across diverse membrane proteins, including multiple GPCRs. Furthermore, we investigated its impact on intracellular cAMP signaling in cells expressing dopamine receptor D1 and α2-adrenergic receptor. Quantitative analyses revealed that light-induced internalization led to reduced surface receptor expression and attenuated ligand-evoked cAMP responses. These findings demonstrate the versatility of the E-fragment system as a platform for studying membrane receptor function and suggest potential applications in therapeutic strategies targeting receptor trafficking and signaling modulation.
14.
Combining light-induced aggregation and biotin proximity labeling implicates endolysosomal proteins in early α-synuclein oligomerization.
Abstract:
Alpha-synuclein (α-syn) aggregation is a defining feature of Parkinson's disease (PD) and related synucleinopathies. Despite significant research efforts focused on understanding α-syn aggregation mechanisms, the early stages of this process remain elusive, largely due to limitations in experimental tools that lack the temporal resolution to capture these dynamic events. Here, we introduce UltraID-LIPA, an innovative platform that combines the light-inducible protein aggregation (LIPA) system with the UltraID proximity-dependent biotinylation assay to identify α-syn-interacting proteins and uncover key mechanisms driving its oligomerization. UltraID-LIPA successfully identified 38 α-syn-interacting proteins, including both established and previously unreported candidates, highlighting the accuracy and robustness of the approach. Notably, a strong interaction with endolysosomal and membrane-associated proteins was observed, supporting the hypothesis that interactions with membrane-bound organelles are pivotal in the early stages of α-syn aggregation. This powerful platform provides new insights into dynamic protein aggregation events, enhancing our understanding of synucleinopathies and other proteinopathies.
15.
KIF2C condensation concentrates PLK1 and phosphorylated BRCA2 on kinetochore microtubules in mitosis.
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Skobelkina , A
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Julien, M
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Jeannin, S
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Miron, S
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Egger, T
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Chaaban, R
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Bouvignies, G
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Alghoul, E
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Ghouil, R
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Friel, C
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Busso, D
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Cañas, JC
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Theillet, FX
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Le Bars, R
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Carreira, A
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Constantinou, A
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Basbous, J
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Zinn-Justin, S
Abstract:
During mitosis, the microtubule depolymerase KIF2C, the tumor suppressor BRCA2, and the kinase PLK1 contribute to the control of kinetochore-microtubule attachments. Both KIF2C and BRCA2 are phosphorylated by PLK1, and BRCA2 phosphorylated at T207 (BRCA2-pT207) serves as a docking site for PLK1. Reducing this interaction results in unstable microtubule-kinetochore attachments. Here we identified that KIF2C also directly interacts with BRCA2-pT207. Indeed, the N-terminal domain of KIF2C adopts a Tudor/PWWP/MBT fold that unexpectedly binds to phosphorylated motifs. Using an optogenetic platform, we found that KIF2C forms membrane-less organelles that assemble through interactions mediated by this phospho-binding domain. KIF2C condensation does not depend on BRCA2-pT207 but requires active Aurora B and PLK1 kinases. Moreover, it concentrates PLK1 and BRCA2-pT207 in an Aurora B-dependent manner. Finally, KIF2C depolymerase activity promotes the formation of KIF2C condensates, but strikingly, KIF2C condensates exclude tubulin: they are located on microtubules, especially at their extremities. Altogether, our results suggest that, during the attachment of kinetochores to microtubules, the assembly of KIF2C condensates amplifies PLK1 and KIF2C catalytic activities and spatially concentrates BRCA2-pT207 at the extremities of microtubules. We propose that this novel and highly regulated mechanism contributes to the control of microtubule-kinetochore attachments, chromosome alignment, and stability.
16.
Engineered depalmitoylases enable selective manipulation of protein localization and function.
Abstract:
S-Palmitoylation is a reversible post-translational modification that tunes the localization, stability, and function of an impressive array of proteins including ion channels, G-proteins, and synaptic proteins. Indeed, altered protein palmitoylation is linked to various human diseases including cancers, neurodevelopmental and neurodegenerative diseases. As such, strategies to selectively manipulate protein palmitoylation with enhanced temporal and subcellular precision are sought after to both delineate physiological functions and as potential therapeutics. Here, we develop chemogenetically and optogenetically inducible engineered depalmitoylases to manipulate the palmitoylation status of target proteins. We demonstrate that this strategy is programmable allowing selective depalmitoylation in specific organelles, triggered by cell-signaling events, and of individual protein complexes. Application of this methodology revealed bidirectional tuning of neuronal excitability by distinct depalmitoylases. Overall, this strategy represents a versatile and powerful method for manipulating protein palmitoylation in live cells, providing insights into their regulation in distinct physiological contexts.
17.
β-Arrestin Condensates Regulate G Protein-Coupled Receptor Function.
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Anderson, PJ
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Xiao, P
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Zhong, Y
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Kaakati, A
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Alfonso-DeSouza, J
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Zhang, T
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Zhang, C
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Yu, K
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Qi, L
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Ding, W
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Liu, S
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Pani, B
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Krishnan, A
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Chen, O
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Jassal, C
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Strawn, J
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Sun, JP
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Rajagopal, S
Abstract:
G protein-coupled receptors (GPCRs) are the largest class of receptors in the genome and control many signaling cascades essential for survival. GPCR signaling is regulated by β-arrestins, multifunctional adapter proteins that direct receptor desensitization, internalization, and signaling. While at many GPCRs, β-arrestins interact with a wide array of signaling effectors, it is unclear how β-arrestins promote such varied functions. Here we show that β-arrestins undergo liquid-liquid phase separation (LLPS) to form condensates that regulate GPCR function. We demonstrate that β-arrestin oligomerization occurs in proximity to the GPCR and regulates GPCR functions such as internalization and signaling. This model is supported by a cryoEM structure of the adhesion receptor ADGRE1 in a 2:2 complex with β-arrestin 1, with a β-arrestin orientation that can promote oligomerization. Our work provides a paradigm for β-arrestin condensates as regulators of GPCR function, with LLPS serving as an important promoter of signaling compartmentalization at GPCRs.
18.
Ferroptosis spreads to neighboring cells via plasma membrane contacts.
Abstract:
Ferroptosis is a lytic, iron-dependent form of regulated cell death characterized by excessive lipid peroxidation and associated with necrosis spread in diseased tissues through unknown mechanisms. Using a novel optogenetic system for light-driven ferroptosis induction via degradation of the anti-ferroptotic protein GPX4, we show that lipid peroxidation and ferroptotic death can spread to neighboring cells through their closely adjacent plasma membranes. Ferroptosis propagation is dependent on cell distance and completely abolished by disruption of α-catenin-dependent intercellular contacts or by chelation of extracellular iron. Remarkably, bridging cells with a lipid bilayer or increasing contacts between neighboring cells enhances ferroptosis spread. Reconstitution of iron-dependent spread of lipid peroxidation between pure lipid, contacting liposomes provides evidence for the physicochemical mechanism involved. Our findings support a model in which iron-dependent lipid peroxidation propagates across proximal plasma membranes of neighboring cells, thereby promoting the transmission of ferroptotic cell death with consequences for pathological tissue necrosis spread.
19.
An improved FLARE system for recording and manipulating neuronal activity.
Abstract:
To address the need for methods for tagging and manipulating neuronal ensembles underlying specific behaviors, we present an improved version of FLARE, termed cytoFLARE (cytosol-expressed FLARE). cytoFLARE incorporates cytosolic tethering of a transcription factor and expression of a more sensitive pair of calcium-sensing domains. We show that cytoFLARE captures more calcium- and light-dependent signals in HEK293T cells and higher signal-to-background ratios in neuronal cultures. We further establish cytoFLARE transgenic Drosophila models and apply cytoFLARE to label activated neurons upon sensory or optogenetic stimulation within a defined time window. Notably, through the cytoFLARE-driven expression of optogenetic actuators, we successfully reactivated and inhibited neurons involved in the larval nociceptive system. Our findings demonstrate the characterization and application of time-gated calcium integrators for both recording and manipulating neuronal activity in Drosophila larvae.
20.
Light-induced expression of gRNA allows for optogenetic gene editing of T lymphocytes in vivo.
Abstract:
There is currently a lack of tools capable of perturbing genes in both a precise and a spatiotemporal fashion. The flexibility of CRISPR (clustered regularly interspaced short palindromic repeats), coupled with light's unparalleled spatiotemporal resolution deliverable from a controllable source, makes optogenetic CRISPR a well-suited solution for precise spatiotemporal gene perturbations. Here, we present a new optogenetic CRISPR tool (Blue Light-inducible Universal VPR-Improved Production of RGRs, BLU-VIPR) that diverges from prevailing split-Cas design strategies and instead focuses on optogenetic regulation of guide RNA (gRNA) production. We engineered BLU-VIPR around a new potent blue-light activated transcription factor (VPR-EL222) and ribozyme-flanked gRNA. The BLU-VIPR design is genetically encoded and ensures precise excision of multiple gRNAs from a single messenger RNA transcript. This simplified spatiotemporal gene perturbation and allowed for several types of optogenetic CRISPR, including indels, CRISPRa, and base editing. BLU-VIPR also worked in vivo with cells previously intractable to optogenetic gene editing, achieving optogenetic gene editing in T lymphocytes in vivo.
21.
POT, an optogenetics-based endogenous protein degradation system.
Abstract:
Precise regulation of protein abundance is critical for cellular homeostasis, whose dysfunction may directly lead to human diseases. Optogenetics allows rapid and reversible control of precisely defined cellular processes, which has the potential to be utilized for regulation of protein dynamics at various scales. Here, we developed a novel optogenetics-based protein degradation system, namely Peptide-mediated OptoTrim-Away (POT) which employs expressed small peptides to effectively target endogenous and unmodified proteins. By engineering the light-induced oligomerization of the E3 ligase TRIM21, POT can rapidly trigger protein degradation via the proteasomal pathway. Our results showed that the developed POT-PI3K and POT-GPX4 modules, which used the iSH2 and FUNDC1 domains to specifically target phosphoinositide 3-kinase (PI3K) and glutathione peroxidase 4 (GPX4) respectively, were able to potently induce the degradation of these endogenous proteins by light. Both live-cell imaging and biochemical experiments validated the potency of these tools in downregulating cancer cell migration, proliferation, and even promotion of cell apoptosis. Therefore, we believe the POT offers an alternative and practical solution for rapid manipulation of endogenous protein levels, and it could potentially be employed to dissect complex signaling pathways in cell and for targeted cellular therapies.
22.
Enhanced or reversible RNA N6-methyladenosine editing by red/far-red light induction.
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Tang, H
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Han, S
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Jie, Y
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Jiang, X
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Zhang, Y
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Peng, J
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Wang, F
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Li, X
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Zhou, X
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Jiang, W
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Weng, X
Abstract:
The RNA N6-methyladenosine (m6A) modification is a critical regulator of various biological processes, but precise and dynamic control of m6A remains a challenge. In this work, we present a red/far-red light-inducible m6A editing system that enables efficient and reversible modulation of m6A levels with minimal off-target effects. By engineering the CRISPR dCas13 protein and sgRNA with two pairs of light-inducible heterodimerizing proteins, ΔphyA/FHY1 and Bphp1/PspR2, we achieved targeted recruitment of m6A effectors. This system significantly enhances m6A writing efficiency and allows dynamic regulation of m6A deposition and removal on specific transcripts, such as SOX2 and ACTB. Notably, reversible m6A editing was achieved through cyclic modulation at a single target site, demonstrating the ability to influence mRNA expression and modulate the differentiation state of human embryonic stem cells. This optogenetic platform offers a precise, versatile tool for cyclic and reversible m6A regulation, with broad implications for understanding RNA biology and its potential applications in research and medicine.
23.
Anti-resonance in developmental signaling regulates cell fate decisions.
Abstract:
Cells process dynamic signaling inputs to regulate fate decisions during development. While oscillations or waves in key developmental pathways, such as Wnt, have been widely observed the principles governing how cells decode these signals remain unclear. By leveraging optogenetic control of the Wnt signaling pathway in both HEK293T cells and H9 human embryonic stem cells, we systematically map the relationship between signal frequency and downstream pathway activation. We find that cells exhibit a minimal response to Wnt at certain frequencies, a behavior we term anti-resonance. We developed both detailed biochemical and simplified hidden variable models that explain how anti-resonance emerges from the interplay between fast and slow pathway dynamics. Remarkably, we find that frequency directly influences cell fate decisions involved in human gastrulation; signals delivered at anti-resonant frequencies result in dramatically reduced mesoderm differentiation. Our work reveals a previously unknown mechanism of how cells decode dynamic signals and how anti-resonance may filter against spurious activation. These findings establish new insights into how cells decode dynamic signals with implications for tissue engineering, regenerative medicine, and cancer biology.
24.
A modular toolbox for the optogenetic deactivation of transcription.
Abstract:
Light-controlled transcriptional activation is a commonly used optogenetic strategy that allows researchers to regulate gene expression with high spatiotemporal precision. The vast majority of existing tools are, however, limited to light-triggered induction of gene expression. Here, we inverted this mode of action and created optogenetic systems capable of efficiently terminating transcriptional activation in response to blue light. First, we designed highly compact regulators by photo-controlling the VP16 (pcVP16) transactivation peptide. Then, applying a two-hybrid strategy, we engineered LOOMINA (light off-operated modular inductor of transcriptional activation), a versatile transcriptional control platform for mammalian cells that is compatible with various effector proteins. Leveraging the flexibility of CRISPR systems, we combined LOOMINA with dCas9 to control transcription with blue light from endogenous promoters with exceptionally high dynamic ranges in multiple cell lines. Functionally and mechanistically, the versatile LOOMINA platform and the exceptionally compact pcVP16 transactivator represent valuable additions to the optogenetic repertoire for transcriptional regulation.
25.
Optogenetic control of Protein Kinase C-epsilon activity reveals its intrinsic signaling properties with spatiotemporal resolution.
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Ong, Q
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Lim, CJY
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Liao, Y
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Tze-Yang Ng, J
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Lim, LTR
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Koh, SXY
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Chan, SE
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Ying, PLY
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Lim, H
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Ye, CR
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Wang, LC
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Ler, SG
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Sobota, RM
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Tan, YS
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Shulman, GI
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Yang, X
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Han, W
Abstract:
The regulation of PKC epsilon (PKCε) and its downstream effects is still not fully understood, making it challenging to develop targeted therapies or interventions. A more precise tool that enables spatiotemporal control of PKCε activity is thus required. Here, we describe a photo-activatable optogenetic PKCε probe (Opto-PKCε) consisting of an engineered PKCε catalytic domain and a blue-light inducible dimerization domain. Molecular dynamics and AlphaFold simulations enable rationalization of the dark-light activity of the optogenetic probe. We first characterize the binding partners of Opto-PKCε, which are similar to those of PKCε. Subsequent validation of the Opto-PKCε tool is performed with phosphoproteome analysis, which reveals that only PKCε substrates are phosphorylated upon light activation. Opto-PKCε could be engineered for recruitment to specific subcellular locations. Activation of Opto-PKCε in isolated hepatocytes reveals its sustained activation at the plasma membrane is required for its phosphorylation of the insulin receptor at Thr1160. In addition, Opto-PKCε recruitment to the mitochondria results in its lowering of the spare respiratory capacity through phosphorylation of complex I NDUFS4. These results demonstrate that Opto-PKCε may have broad applications for the studies of PKCε signaling with high specificity and spatiotemporal resolution.
