Curated Optogenetic Publication Database

Search precisely and efficiently by using the advantage of the hand-assigned publication tags that allow you to search for papers involving a specific trait, e.g. a particular optogenetic switch or a host organism.

Qr: journal:"bioRxiv"
Showing 51 - 75 of 142 results
51.

Activation of NF-κB signaling by optogenetic clustering of IKKα and β.

blue CRY2/CRY2 CRY2olig HEK293T Signaling cascade control Organelle manipulation
bioRxiv, 12 Jun 2024 DOI: 10.1101/2024.06.12.598631 Link to full text
Abstract: A large percentage of proteins form higher-order structures in order to fulfill their function. These structures are crucial for the precise spatial and temporal regulation of the cellular signaling network. Investigation of this network requires sophisticated research tools, such as optogenetic tools, that allow dynamic control over the signaling molecules. Cryptochrome 2 and its variations are the best-characterized oligomerizing photoreceptors the optogenetics toolbox has to offer. Therefore, we utilized this switch and combined it with an eGFP-binding nanobody, to build a toolbox of optogenetic constructs that enables the oligomerization of any eGFP-tagged protein of interest. We further introduced the higher clustering variant Cry2olig and an intrinsically disordered region to create higher-order oligomers or phase-separated assemblies to investigate the impact of different oligomerization states on eGFP-tagged signaling molecules. We apply these constructs to cluster IKKα and IKKβ, which resemble the central signaling integrator of the NF-κB pathway, thereby engineer a potent, blue-light-inducible activator of NF-κB signaling.
52.

Illuminating morphogen and patterning dynamics with optogenetic control of morphogen production.

blue VVD mESCs Cell differentiation Endogenous gene expression
bioRxiv, 11 Jun 2024 DOI: 10.1101/2024.06.11.598403 Link to full text
Abstract: Cells use dynamic spatial and temporal cues to instruct cell fate decisions during development. Morphogens are key examples, where the concentration and duration of morphogen exposure produce distinct cell fates that drive tissue patterning. Studying the dynamics of these processes has been challenging. Here, we establish an optogenetic system for morphogen production that enables the investigation of developmental patterning in vitro. Using a tunable light-inducible gene expression system, we generate long-range Shh gradients that pattern neural progenitors into spatially distinct progenitor domains mimicking the spatial arrangement of neural progenitors found in vivo during vertebrate neural tube development. With this system, we investigate how biochemical features of Shh and the presence of morphogen-interacting proteins affect the patterning length scale. We measure tissue clearance rates, revealing that Shh has an extracellular half-life of about 1h, and we probe how the level and duration of morphogen exposure govern the acquisition and maintenance of cell fates. The rate of Shh turnover is substantially faster than the downstream gene expression dynamics, indicating that the gradient is continually renewed during patterning. Together the optogenetic approach establishes a simple experimental system for the quantitative interrogation of morphogen patterning. Controlling morphogen dynamics in a reproducible manner provides a framework to dissect the interplay between biochemical cues, the biophysics of gradient formation, and the transcriptional programmes underlying developmental patterning.
53.

AGS3-based optogenetic GDI induces GPCR-independent Gβγ signaling and macrophage migration.

blue CRY2/CIB1 HeLa RAW264.7 Signaling cascade control
bioRxiv, 5 Jun 2024 DOI: 10.1101/2024.06.04.597473 Link to full text
Abstract: G protein-coupled receptors (GPCRs) are efficient Guanine nucleotide exchange factors (GEFs) and exchange GDP to GTP on the Gα subunit of G protein heterotrimers in response to various extracellular stimuli, including neurotransmitters and light. GPCRs primarily broadcast signals through activated G proteins, GαGTP, and free Gβγ and are major disease drivers. Evidence shows that the ambient low threshold signaling required for cells is likely supplemented by signaling regulators such as non-GPCR GEFs and Guanine nucleotide Dissociation Inhibitors (GDIs). Activators of G protein Signaling 3 (AGS3) are recognized as a GDI involved in multiple health and disease-related processes. Nevertheless, understanding of AGS3 is limited, and no significant information is available on its structure-function relationship or signaling regulation in living cells. Here, we employed in silico structure-guided engineering of a novel optogenetic GDI, based on the AGS3’s G protein regulatory (GPR) motif, to understand its GDI activity and induce standalone Gβγ signaling in living cells on optical command. Our results demonstrate that plasma membrane recruitment of OptoGDI efficiently releases Gβγ, and its subcellular targeting generated localized PIP3 and triggered macrophage migration. Therefore, we propose OptoGDI as a powerful tool for optically dissecting GDI-mediated signaling pathways and triggering GPCR-independent Gβγ signaling in cells and in vivo.
54.

Large-scale control over collective cell migration using light-controlled epidermal growth factor receptors.

blue CRY2/CRY2 iLID hTERT RPE-1 MCF10A Signaling cascade control Control of cytoskeleton / cell motility / cell shape Organelle manipulation
bioRxiv, 31 May 2024 DOI: 10.1101/2024.05.30.596676 Link to full text
Abstract: Receptor tyrosine kinases (RTKs) are thought to play key roles in coordinating cell movement at single-cell and tissue scales. The recent development of optogenetic tools for controlling RTKs and their downstream signaling pathways suggested these responses may be amenable to engineering-based control for sculpting tissue shape and function. Here, we report that a light-controlled EGF receptor (OptoEGFR) can be deployed in epithelial cell lines for precise, programmable control of long-range tissue movements. We show that in OptoEGFR-expressing tissues, light can drive millimeter-scale cell rearrangements to densify interior regions or produce rapid outgrowth at tissue edges. Light-controlled tissue movements are driven primarily by PI 3-kinase signaling, rather than diffusible signals, tissue contractility, or ERK kinase signaling as seen in other RTK-driven migration contexts. Our study suggests that synthetic, light-controlled RTKs could serve as a powerful platform for controlling cell positions and densities for diverse applications including wound healing and tissue morphogenesis.
55.

Luminescent ingestible electronic capsules for in vivo regulation of optogenetic engineered bacteria.

green CcaS/CcaR E. coli Transgene expression
bioRxiv, 24 May 2024 DOI: 10.1101/2024.05.24.595681 Link to full text
Abstract: The ideal engineered microbial smart-drug should be capable of functioning on demand at specific sites in vivo. However, precise regulation of engineered microorganisms poses challenges in the convoluted and elongated intestines. Despite the promising application potential of optogenetic regulation strategies based on light signals, the poor tissue penetration of light signals limits their application in large experimental animals. Given the rapid development of ingestible electronic capsules in recent years, taking advantage of them as regulatory devices to deliver light signals in situ to engineered bacteria within the intestines has become feasible. In this study, we established an electronic-microorganism signaling system, realized by two Bluetooth-controlled luminescent electronic capsules were designed. The “Manager” capsule is equipped with a photosensor to monitor the distribution of engineered bacteria and to activate the optogenetic function of the bacteria by emitting green light. The other capsule, “Locator”, can control the in situ photopolymerization of hydrogels in the intestines via ultraviolet light, aiding in the retention of engineered bacteria at specific sites. These two electronic capsules are expected to work synergistically to regulate the distribution and function of engineered bacteria in vivo, and their application in the treatment of colitis in pigs is currently being investigated, with relevant results to be updated subsequently.
56.

A modular strategy for extracellular vesicle-mediated CRISPR-Cas9 delivery through aptamer-based loading and UV-activated cargo release.

violet PhoCl HEK293T in vitro Control of intracellular / vesicular transport
bioRxiv, 24 May 2024 DOI: 10.1101/2024.05.24.595612 Link to full text
Abstract: CRISPR-Cas9 gene editing technology offers the potential to permanently repair genes containing pathological mutations. However, efficient intracellular delivery of the Cas9 ribonucleoprotein complex remains one of the major hurdles in its therapeutic application. Extracellular vesicles (EVs) are biological nanosized membrane vesicles released by cells, that play an important role in intercellular communication. Due to their innate capability of intercellular transfer of proteins, RNA, and various other biological cargos, EVs have emerged as a novel promising strategy for the delivery of macromolecular biotherapeutics, including CRISPR-Cas9 ribonucleoproteins. Here, we present a versatile, modular strategy for the loading and delivery of Cas9. We leverage the high affinity binding of MS2 coat proteins (MCPs) fused to EV-enriched proteins to MS2 aptamers incorporated into single guide RNAs (sgRNAs), in combination with a UV-activated photocleavable linker domain, PhoCl. Combined with the Vesicular stomatitis virus G (VSV-G) protein this modular platform enables efficient loading and subsequent delivery of the Cas9 ribonucleoprotein complex, which shows critical dependence on the incorporation and activation of the photocleavable linker domain. As this approach does not require any direct fusion of Cas9 to EV-enriched proteins, we demonstrate that Cas9 can readily be exchanged for other variants, including transcriptional activator dCas9-VPR and adenine base editor ABE8e, as confirmed by various sensitive fluorescent reporter assays. Taken together, we describe a robust and modular strategy for successful Cas9 delivery, which can be applied for CRISPR-Cas9-based genetic engineering as well as transcriptional regulation, underlining the potential of EV-mediated strategies for the treatment of genetic diseases.
57.

Ubiquitin-driven protein condensation initiates clathrin-mediated endocytosis.

blue CRY2/CRY2 SUM-159 Control of intracellular / vesicular transport Organelle manipulation
bioRxiv, 19 May 2024 DOI: 10.1101/2023.08.21.554139 Link to full text
Abstract: Clathrin-mediated endocytosis is an essential cellular pathway that enables signaling and recycling of transmembrane proteins and lipids. During endocytosis, dozens of cytosolic proteins come together at the plasma membrane, assembling into a highly interconnected network that drives endocytic vesicle biogenesis. Recently, multiple groups have reported that early endocytic proteins form flexible condensates, which provide a platform for efficient assembly of endocytic vesicles. Given the importance of this network in the dynamics of endocytosis, how might cells regulate its stability? Many receptors and endocytic proteins are ubiquitylated, while early endocytic proteins such as Eps15 contain ubiquitin-interacting motifs. Therefore, we examined the influence of ubiquitin on the stability of the early endocytic protein network. In vitro, we found that recruitment of small amounts of polyubiquitin dramatically increased the stability of Eps15 condensates, suggesting that ubiquitylation could nucleate endocytic assemblies. In live cell imaging experiments, a version of Eps15 that lacked the ubiquitin-interacting motif failed to rescue defects in endocytic initiation created by Eps15 knockout. Furthermore, fusion of Eps15 to a deubiquitylase enzyme destabilized nascent endocytic sites within minutes. In both in vitro and live cell settings, dynamic exchange of Eps15 proteins, a hallmark of liquid like systems, was modulated by Eps15-Ub interactions. These results collectively suggest that ubiquitylation drives assembly of the flexible protein network responsible for catalyzing endocytic events. More broadly, this work illustrates a biophysical mechanism by which ubiquitylated transmembrane proteins at the plasma membrane could regulate the efficiency of endocytic recycling.
58.

Kinetic properties of optogenetic DNA editing by LiCre-loxP.

blue AsLOV2 S. cerevisiae Transgene expression Nucleic acid editing
bioRxiv, 18 May 2024 DOI: 10.1101/2024.05.17.594525 Link to full text
Abstract: Previously, we developed an optogenetic tool made of a single chimeric protein called LiCre that enables the edition of specific changes in the genome of live cells with blue light via DNA recombination between loxP sites (Duplus-Bottin et al., 2021). Here, we used in vitro and in vivo experiments combined with kinetic modeling to provide a deeper characterization of the photo-activated LiCre-loxP recombination reaction. We find that LiCre binds DNA with high affinity in absence of light stimulus, that this binding is cooperative although not as much as for the Cre recombinase from which LiCre was derived and that increasing temperature from 20°C to 37°C gradually increased LiCre efficiency. The recombination kinetics in live cells can be explained by a model where photo-activation of two or more DNA-bound LiCre units (happening in seconds) can produce (in several minutes) a functional recombination synapse. Our conclusions provide helpful guidelines to induce specific genetic changes in live cells using light.
59.

Endogenous OptoRhoGEFs reveal biophysical principles of epithelial tissue furrowing.

blue iLID D. melanogaster in vivo Control of cytoskeleton / cell motility / cell shape Developmental processes
bioRxiv, 12 May 2024 DOI: 10.1101/2024.05.12.593711 Link to full text
Abstract: During development, epithelia function as malleable substrates that undergo extensive remodeling to shape developing embryos. Optogenetic control of Rho signaling provides an avenue to investigate the mechanisms of epithelial morphogenesis, but transgenic optogenetic tools can be limited by variability in tool expression levels and deleterious effects of transgenic overexpression on development. Here, we use CRISPR/Cas9 to tag Drosophila RhoGEF2 and Cysts/Dp114RhoGEF with components of the iLID/SspB optogenetic heterodimer, permitting light-dependent control over endogenous protein activities. Using quantitative optogenetic perturbations, we uncover a dose-dependence of tissue furrow depth and bending behavior on RhoGEF recruitment, revealing mechanisms by which developing embryos can shape tissues into particular morphologies. We show that at the onset of gastrulation, furrows formed by cell lateral contraction are oriented and size-constrained by a stiff basal actomyosin layer. Our findings demonstrate the use of quantitative, 3D-patterned perturbations of cell contractility to precisely shape tissue structures and interrogate developmental mechanics.
60.

PhoCoil: An Injectable and Photodegradable Single-component Recombinant Protein Hydrogel for Localized Therapeutic Cell Delivery.

violet PhoCl in vitro Extracellular optogenetics
bioRxiv, 10 May 2024 DOI: 10.1101/2024.05.07.592971 Link to full text
Abstract: Hydrogel biomaterials offer great promise for 3D cell culture and therapeutic delivery. Despite many successes, challenges persist in that gels formed from natural proteins are only marginally tunable while those derived from synthetic polymers lack intrinsic bioinstructivity. Towards the creation of biomaterials with both excellent biocompatibility and customizability, recombinant protein-based hydrogels have emerged as molecularly defined and user-programmable platforms that mimic the proteinaceous nature of the extracellular matrix. Here, we introduce PhoCoil, a dynamically tunable recombinant hydrogel formed from a single protein component with unique multi-stimuli responsiveness. Physical crosslinking through coiled-coil interactions promotes rapid shear-thinning and self-healing behavior, rendering the gel injectable, while an included photodegradable motif affords on-demand network dissolution via visible light. PhoCoil gel photodegradation can be spatiotemporally and lithographically controlled in a dose-dependent manner, through complex tissue, and without harm to encapsulated cells. We anticipate that PhoCoil will enable new applications in tissue engineering and regenerative medicine.
61.

Chromatin condensates tune nuclear mechano-sensing in Kabuki Syndrome by constraining cGAS activation.

blue CRY2/CRY2 hMSCs NIH/3T3 Organelle manipulation
bioRxiv, 6 May 2024 DOI: 10.1101/2024.05.06.592652 Link to full text
Abstract: Cells and tissue integrity is constantly challenged by the necessity to adapt and respond to mechanical loads. Among the cellular components, the nucleus possesses mechano-sensing and mechanotransduction capabilities, yet the molecular mechanisms involved remain poorly defined. We postulated that the mechanical properties of the chromatin and its compartmentalization into condensates contribute to the nuclear adaptation to external forces, while preserving its integrity. By interrogating the effects of MLL4 loss-of-function in Kabuki Syndrome, we found that the balancing of transcriptional and Polycomb condensates tunes the nuclear responsiveness to external mechanical forces. We showed that MLL4 acts as a chromatin mechano-sensor by clustering into condensates through its Prion-like domain, and its response was regulated by the chromatin context. Furthermore, the mechano-sensing activity of MLL4 condensates is instrumental to withstand the physical challenges that nuclei experience during cell confinement and migration by preserving their integrity. In Kabuki Syndrome persistent rupture of nuclear envelope triggers cGAS-STING activation, which leads to programmed cell death. Ultimately, these results demonstrate the critical role chromatin compartments play in mechano-responses and how they impact pathological conditions by stimulating cGAS-STING signaling.
62.

Crystal structure of a bacterial photoactivated adenylate cyclase determined at room temperature by serial femtosecond crystallography.

blue BLUF domains Background
bioRxiv, 26 Apr 2024 DOI: 10.1101/2024.04.21.590439 Link to full text
Abstract: OaPAC is a recently discovered blue-light using flavin adenosine dinucleotide (BLUF) photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata that uses adenosine triphosphate and translates the light signal into the production of cyclic adenosine monophosphate. Here, we report the crystal structures of the enzyme in the absence of its natural substrate determined from room temperature serial crystallography data collected at both an X-ray free electron laser and a synchrotron and we compare them with the cryo macromolecular crystallography structures obtained at a synchrotron by us and others. These results reveal slight differences in the structure of the enzyme due to data collection at different temperatures and X-ray sources. We further investigate the effect of the Y6 mutation in the blue-light using flavin adenosine dinucleotide domain, a mutation which results in a rearrangement of the hydrogen-bond network around the flavin and a notable rotation of the side_x0002_chain of the criticalQ48 residue. These studies pave the way for ps - ms time-resolved serial crystallography experiments at X-ray free electron lasers and synchrotrons in order to determine the early structural intermediates and correlate them with the well-studied ps - ms spectroscopic intermediates.
63.

Myosin II actively regulates Drosophila proprioceptors.

blue CRY2/CIB1 D. melanogaster in vivo Control of cytoskeleton / cell motility / cell shape
bioRxiv, 21 Apr 2024 DOI: 10.1101/2024.04.18.590050 Link to full text
Abstract: Auditory receptors can be motile to actively amplify their mechanical input. Here we describe a novel and different type of motility that, residing in supporting cells, shapes physiological responses of mechanoreceptor cells. In Drosophila larvae, supporting cap cells transmit mechanical stimuli to proprioceptive chordotonal neurons. We found that the cap cells are strongly pre-stretched at rest to twice their relaxed length. The tension in these cells is modulated by non-muscle myosin-II motors. Activating the motors optogenetically causes contractions of the cap cells. Cap-cell-specific knockdown of the regulatory light chain of myosin-II alters mechanically evoked receptor neuron responses, converting them from phasic to more tonic, impairing sensory adaptation. Hence, two motile mechanisms seem to operate in concert in insect chordotonal organs, one in the sensory receptor neurons, based on dynein, and the other in supporting cells, based on myosin.
64.

Focal adhesion-derived liquid-liquid phase separations regulate mRNA translation.

blue CRY2/CRY2 MCF7 Organelle manipulation
bioRxiv, 18 Apr 2024 DOI: 10.1101/2023.11.22.568289 Link to full text
Abstract: Liquid-liquid phase separation (LLPS) has emerged as a major organizing principle in cells. Recent work showed that multiple components of integrin-mediated focal adhesions including p130Cas can form LLPS, which govern adhesion dynamics and related cell behaviors. In this study, we found that the focal adhesion protein p130Cas drives formation of structures with the characteristics of LLPS that bud from focal adhesions into the cytoplasm. Condensing concentrated cytoplasm around p130Cas-coated beads allowed their isolation, which were enriched in a subset of focal adhesion proteins, mRNAs and RNA binding proteins, including those implicated in inhibiting mRNA translation. Plating cells on very high concentrations of fibronectin to induce large focal adhesions inhibited message translation which required p130Cas and correlated with droplet formation. Photo-induction of p130Cas condensates using the Cry2 system also reduced translation. These results identify a novel regulatory mechanism in which high adhesion limits message translation via induction of p130Cas-dependent cytoplasmic LLPS. This mechanism may contribute to the quiescent state of very strongly adhesive myofibroblasts and senescent cells.
65.

A protein condensation network contextualises cell fate decisions.

blue CRY2olig S. cerevisiae Cell cycle control Organelle manipulation
bioRxiv, 18 Apr 2024 DOI: 10.1101/2024.04.18.590070 Link to full text
Abstract: For cells to thrive, they must make appropriate fate decisions based on a myriad of internal and external stimuli. But how do they integrate these different forms of information to contextualise their decisions? Old yeast cells showed an ability to dampen their proliferation as they entered senescence. Conversely, they had an enhanced ability to promote proliferation during escape from pheromone stimulation. A network of nucleoprotein condensation states involving processing bodies (P-bodies) and the prion-like RNA-binding protein, Whi3, controlled these opposing fate decisions. In old but not in young cells, condensation of Whi3 was both necessary and sufficient for senescence entry. In old cells, Whi3 localised to age-dependent P-bodies. Preventing their formation stopped Whi3 condensation from driving senescence entry. Challenging old cells with an external stimulus, pheromone, revealed that the condensates had a second function: potentiating the cell's ability to trigger escape from the mating pheromone response. These findings identify biomolecular condensation as an integrator of contextual information as cells make decisions, enabling them to navigate overlapping life events.
66.

KIF2C-induced nuclear condensation concentrates PLK1 and phosphorylated BRCA2 at the kinetochore microtubules in mitosis.

blue CRY2olig HEK293 Organelle manipulation
bioRxiv, 14 Apr 2024 DOI: 10.1101/2024.04.13.589357 Link to full text
Abstract: During mitosis, the human microtubule depolymerase KIF2C increases the turnover of kinetochore-microtubule attachments. This facilitates the correction of attachment errors. Moreover, BRCA2 phosphorylated at Thr207 by PLK1 (BRCA2-pT207) assembles a complex including PLK1, PP2A and BUBR1 that contributes to the stability of the kinetochore-microtubule attachments. PLK1, together with Aurora B, critically regulate the accurate segregation of chromosomes. Here we demonstrate that KIF2C contains an N-terminal domain that binds directly to several phosphorylated peptides, including BRCA2-pT207. Using an optogenetic platform, we reveal that KIF2C assembles into membrane-less compartments or biomolecular condensates that are located next to microtubules. We provide evidence that condensate assembly depends on the presence of the newly defined N-terminal phospho-binding domain of KIF2C and on the kinase activities of Aurora B and PLK1. Moreover, KIF2C condensates concentrate active PLK1 and colocalize with BRCA2-pT207. We propose that, because of its phospho-dependent binding and oligomerization capacities, KIF2C forms biomolecular condensates that partition PLK1 and locally amplify its kinase activity during mitosis.
67.

Optogenetic control of Nodal signaling patterns.

blue CRY2/CIB1 VfAU1-LOV zebrafish in vivo Developmental processes
bioRxiv, 12 Apr 2024 DOI: 10.1101/2024.04.11.588875 Link to full text
Abstract: A crucial step in early embryogenesis is the establishment of spatial patterns of signaling activity. Tools to perturb morphogen signals with high resolution in space and time can help reveal how embryonic cells decode these signals to make appropriate fate decisions. Here, we present new optogenetic reagents and an experimental pipeline for creating designer Nodal signaling patterns in live zebrafish embryos. Nodal receptors were fused to the light sensitive heterodimerizing pair Cry2/CIB1N, and the Type II receptor was sequestered to the cytosol. The improved optoNodal2 reagents eliminate dark activity and improve response kinetics, without sacrificing dynamic range. We adapted an ultra-widefield microscopy platform for parallel light patterning in up to 36 embryos and demonstrated precise spatial control over Nodal signaling activity and downstream gene expression. Patterned Nodal activation drove precisely controlled internalization of endodermal precursors. Further, we used patterned illumination to generate synthetic signaling patterns in Nodal signaling mutants, rescuing several characteristic developmental defects. This study establishes an experimental toolkit for systematic exploration of Nodal signaling patterns in live embryos.
68.

The Dystrophin-Dystroglycan complex ensures cytokinesis efficiency in Drosophila epithelia.

blue CRY2/CIB1 D. melanogaster in vivo Control of cytoskeleton / cell motility / cell shape
bioRxiv, 14 Mar 2024 DOI: 10.1101/2024.03.14.585005 Link to full text
Abstract: Cytokinesis physically separates daughter cells at the end of cell division. This step is particularly challenging for epithelial cells, which are connected to their neighbors and to the extracellular matrix by transmembrane protein complexes. To systematically evaluate the impact of the cell adhesion machinery on epithelial cytokinesis efficiency, we performed an RNAi-based modifier screen in the Drosophila follicular epithelium. Strikingly, this unveiled adhesion molecules and transmembrane receptors that facilitate cytokinesis completion. Among these is Dystroglycan, which connects the extracellular matrix to the cytoskeleton via Dystrophin. Live imaging revealed that Dystrophin and Dystroglycan become enriched in the ingressing membrane, below the cytokinetic ring, during and after ring constriction. Using multiple alleles, including Dystrophin isoform-specific mutants, we show that Dystrophin/Dystroglycan localization is linked with unanticipated roles in regulating cytokinetic ring contraction and in preventing membrane regression during the abscission period. Altogether, we provide evidence that, rather than opposing cytokinesis completion, the machinery involved in cell-cell and cell-matrix interactions has also evolved functions to ensure cytokinesis efficiency in epithelial tissues.
69.

Protein supersaturation powers innate immune signaling.

blue CRY2clust HEK293T THP-1 Cell death
bioRxiv, 3 Mar 2024 DOI: 10.1101/2023.03.20.533581 Link to full text
Abstract: Innate immunity protects us in youth but turns against us as we age. The reason for this tradeoff is unclear. Seeking a thermodynamic basis, we focused on death fold domains (DFDs), whose ordered polymerization has been stoichiometrically linked to innate immune signal amplification. We hypothesized that soluble ensembles of DFDs function as phase change batteries that store energy via supersaturation and subsequently release it through nucleated polymerization. Using imaging and FRET-based cytometry to characterize the phase behaviors of all 109 human DFDs, we found that the hubs of innate immune signaling networks encode large nucleation barriers that are intrinsically insulated from cross-pathway activation. We showed via optogenetics that supersaturation drives signal amplification and that the inflammasome is constitutively supersaturated in vivo. Our findings reveal that the soluble “inactive” states of adaptor DFDs function as essential, yet impermanent, kinetic barriers to inflammatory cell death, suggesting a thermodynamic driving force for aging.
70.

Light-directed evolution of dynamic, multi-state, and computational protein functionalities.

blue red EL222 PhyB/PIF3 S. cerevisiae Cell cycle control Transgene expression
bioRxiv, 2 Mar 2024 DOI: 10.1101/2024.02.28.582517 Link to full text
Abstract: Directed evolution is a powerful method in biological engineering. Current approaches were devised for evolving steady-state properties such as enzymatic activity or fluorescence intensity. A fundamental problem remains how to evolve dynamic, multi-state, or computational functionalities, e.g., folding times, on-off kinetics, state-specific activity, stimulus-responsiveness, or switching and logic capabilities. These require applying selection pressure on all of the states of a protein of interest (POI) and the transitions between them. We realized that optogenetics and cell cycle oscillations could be leveraged for a novel directed evolution paradigm (‘optovolution’) that is germane for this need: We designed a signaling cascade in budding yeast where optogenetic input switches the POI between off (0) and on (1) states. In turn, the POI controls a Cdk1 cyclin, which in the re-engineered cell cycle system is essential for one cell cycle stage but poisonous for another. Thus, the cyclin must oscillate (1-0-1-0…) for cell proliferation. In this system, evolution can act efficiently on the dynamics, transient states, and input-output relations of the POI in every cell cycle. Further, controlling the pacemaker, light, directs and tunes selection pressures. Optovolution is in vivo, continuous, self-selecting, and genetically robust. We first evolved two optogenetic systems, which relay 0/1 input to 0/1 output: We obtained 25 new variants of the widely used LOV transcription factor El222. These mutants were stronger, less leaky, or green- and red-responsive. The latter was conjectured to be impossible for LOV domains but is needed for multiplexing and lowering phototoxicity. Evolving the PhyB-Pif3 optogenetic system, we discovered that loss of YOR1 makes supplementing the expensive and unstable chromophore phycocyanobilin (PCB) unnecessary. Finally, we demonstrate the generality of the method by creating and evolving a destabilized rtTA transcription factor, which performs an AND operation between transcriptional and doxycycline input. Optovolution makes coveted, difficult-to-change protein functionalities evolvable.
71.

Light-Guided Rabies Virus Tracing for Neural Circuit Analysis.

red PhyB/PIF3 rat cortical neurons Transgene expression
bioRxiv, 23 Feb 2024 DOI: 10.1101/2023.03.04.531104 Link to full text
Abstract: Neuronal tracing methods are essential tools to understand the fundamental architecture of neural circuits and their connection to the overall functional behavior of the brain. Viral vectors used to map these transsynaptic connections are capable of cell-type-specific and directional-specific labeling of the neuronal connections. Herein, we describe a novel approach to guide the transsynaptic spreading of the Rabies Virus (RV) retrograde tracer using light. We built a Baculovirus (BV) as a helper virus to deliver all the functional components necessary and sufficient for a nontoxic RV to spread from neuron to neuron, with a light-actuated gene switch to control the RV polymerase, the L gene. This design should allow for precisely controlled polysynaptic viral tracing with minimal viral toxicity. To use this system in a highly scalable and automated manner, we built optoelectronics for controlling this system in vitro with a large field of view using an off-the-shelf CMOS sensor, OLED display panel, and microcontrollers. We describe the assembly of these genetic circuits using the uLoop DNA assembly method and a library of genetic parts designed for the uLoop system. Combining these tools provides a framework for increasing the capabilities of nontoxic tracing through multiple synapses and increasing the throughput of neural tracing using viruses.
72.

Optogenetic Regulation of EphA1 RTK Activation and Signaling.

blue CRY2olig HEK293T Neuro-2a Signaling cascade control Control of cytoskeleton / cell motility / cell shape
bioRxiv, 20 Feb 2024 DOI: 10.1101/2024.02.06.579139 Link to full text
Abstract: Eph receptors are ubiquitous class of transmembrane receptors that mediate cell-cell communication, proliferation, differentiation, and migration. EphA1 receptors specifically play an important role in angiogenesis, fetal development, and cancer progression; however, studies of this receptor can be challenging as its ligand, ephrinA1, binds and activates several EphA receptors simultaneously. Optogenetic strategies could be applied to circumvent this requirement for ligand activation and enable selective activation of the EphA1 subtype. In this work, we designed and tested several iterations of an optogenetic EphA1 - Cryptochrome 2 (Cry2) fusion, investigating their capacity to mimic EphA1-dependent signaling in response to light activation. We then characterized the key cell signaling target of MAPK phosphorylation activated in response to light stimulation. The optogenetic regulation of Eph receptor RTK signaling without the need for external stimulus promises to be an effective means of controlling individual Eph receptor-mediated activities and creates a path forward for the identification of new Eph-dependent functions.
73.

A temperature-inducible protein module for control of mammalian cell fate.

blue BcLOV4 HEK293T Signaling cascade control Control of cytoskeleton / cell motility / cell shape Cell death
bioRxiv, 19 Feb 2024 DOI: 10.1101/2024.02.19.581019 Link to full text
Abstract: Inducible protein switches are used throughout the biosciences to allow on-demand control of proteins in response to chemical or optical inputs. However, these inducers either cannot be controlled with precision in space and time or cannot be applied in optically dense settings, limiting their application in tissues and organisms. Here we introduce a protein module whose active state can be reversibly toggled with a small change in temperature, a stimulus that is both penetrant and dynamic. This protein, called Melt (Membrane localization through temperature), exists as a monomer in the cytoplasm at elevated temperatures but both oligomerizes and translocates to the plasma membrane when temperature is lowered. Using custom devices for rapid and high-throughput temperature control during live-cell microscopy, we find that the original Melt variant fully switches states between 28-32°C, and state changes can be observed within minutes of temperature changes. Melt was highly modular, permitting thermal control over diverse intracellular processes including signaling, proteolysis, and nuclear shuttling through straightforward end-to-end fusions with no further engineering. Melt was also highly tunable, giving rise to a library of Melt variants with switch point temperatures ranging from 30-40°C. The variants with higher switch points allowed control of molecular circuits between 37°C-41°C, a well-tolerated range for mammalian cells. Finally, Melt could thermally regulate important cell decisions over this range, including cytoskeletal rearrangement and apoptosis. Thus Melt represents a versatile thermogenetic module that provides straightforward, temperature-based, real-time control of mammalian cells with broad potential for biotechnology and biomedicine.
74.

Optogenetic control of pheromone gradients reveals functional limits of mating behavior in budding yeast.

blue EL222 S. cerevisiae Signaling cascade control Endogenous gene expression
bioRxiv, 8 Feb 2024 DOI: 10.1101/2024.02.06.578657 Link to full text
Abstract: Cell-cell communication through diffusible signals allows distant cells to coordinate biological functions. Such coordination depends on the signal landscapes generated by emitter cells and the sensory capacities of receiver cells. In contrast to morphogen gradients in embryonic development, microbial signal landscapes occur in open space with variable cell densities, spatial distributions, and physical environments. How do microbes shape signal landscapes to communicate robustly under such circumstances remains an unanswered question. Here we combined quantitative spatial optogenetics with biophysical theory to show that in the mating system of budding yeast— where two mates communicate to fuse—signal landscapes convey demographic or positional information depending on the spatial organization of mating populations. This happens because α-factor pheromone and its mate-produced protease Bar1 have characteristic wide and narrow diffusion profiles, respectively. Functionally, MATα populations signal their presence as collectives, but not their position as individuals, and Bar1 is a sink of alpha-factor, capable of both density-dependent global attenuation and local gradient amplification. We anticipate that optogenetic control of signal landscapes will be instrumental to quantitatively understand the spatial behavior of natural and engineered cell-cell communication systems.
75.

Temporal dynamics of BMP/Nodal ratio drive tissue-specific gastrulation morphogenesis.

blue CRY2/CIB1 zebrafish in vivo Signaling cascade control Developmental processes
bioRxiv, 7 Feb 2024 DOI: 10.1101/2024.02.06.579243 Link to full text
Abstract: Anteroposterior (AP) elongation of the vertebrate body plan is driven by convergence and extension (C&E) gastrulation movements in both the mesoderm and neuroectoderm, but how or whether molecular regulation of C&E differs between tissues remains an open question. Using a zebrafish explant model of AP axis extension, we show that C&E of the neuroectoderm and mesoderm can be uncoupled ex vivo, and that morphogenesis of individual tissues results from distinct morphogen signaling dynamics. Using precise temporal manipulation of BMP and Nodal signaling, we identify a critical developmental window during which high or low BMP/Nodal ratios induce neuroectoderm- or mesoderm-driven C&E, respectively. Increased BMP activity similarly enhances C&E specifically in the ectoderm of intact zebrafish gastrulae, highlighting the in vivo relevance of our findings. Together, these results demonstrate that temporal dynamics of BMP and Nodal morphogen signaling activate distinct morphogenetic programs governing C&E gastrulation movements within individual tissues.
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