Biology subjects

Chen, Y.-C.

Publications and source records attributed to Chen, Y.-C..

At least 73 records · Page 4Linked to original sources

bioRxiv2023

Spatial patterning regulates neuron numbers in the Drosophila visual system

Neurons must be made in the correct proportions to communicate with the appropriate synaptic partners and form functional circuits. In the Drosophila visual system, multiple subtypes of Distal medulla (Dm) inhibitory interneurons are made in distinct, reproducible numbers--from 5 to 800 per optic lobe. These neurons are born from a crescent-shaped neuroepithelium called the Outer Proliferation Center (OPC), which can be subdivided into specific domains based on transcription factor expression. We fate mapped Dm neurons and found that more abundant neural types are born from larger neuroepithelial subdomains, while less abundant subtypes are born from smaller ones. Additionally, morphogenetic Dpp/BMP signaling provides a second layer of patterning that subdivides the neuroepithelium into smaller domains to provide more granular control of cell proportions. Apoptosis appears to play a minor role in regulating Dm neuron abundance. This work describes an underappreciated mechanism for the regulation of neuronal stoichiometry.

developmental biology↗

bioRxiv2023

Long-term selection on mitocoding genes buried in mammalian and avian nuclear genomes

Sporadically genetic material that originates from an organelle genome integrates into the nuclear genome. However it is unclear what processes maintain such an integration over longer evolutionary time. Recently it was shown that nuclear DNA of mitochondrial origin (NUMTs) may harbour genes with intact mitochondrial reading frames despite the fact that they are highly divergent to the hosts mitochondrial genome. Two major hypotheses have been put forward to explain the existence of such mitocoding nuclear genes: (A) recent introgression from another species and (B) long-term selection. To address whether these intriguing possibilities do play a role we scanned the genomes of more than 1,000 avian and mammalian species for NUMTs. We indeed identified that the subclass of divergent NUMTs harbouring mitogenes with intact reading frames are widespread across mammals and birds. We can show that for these NUMTs signatures of cross-species introgression are widespread in birds, but not mammals with the exception of ungulates. We can also show that a substantial fraction of deeply divergent NUMTs are maintained by selection. For a small number of NUMT genes we identify an evolutionary signature that is consistent with adaptive evolution including one human NUMT that is shared among seven ape species. This highlights the intriguing possibility that NUMT insertions occasionally may be functional.

evolutionary biology↗

bioRxiv2023

An inducible germ cell ablation chicken model for high-grade germline chimeras

Chicken embryos are a powerful and widely used animal model in developmental biology studies. After the development of CRISPR technology, gene-edited chickens have been generated by transferring primordial germ cells (PGCs) after genetic modifications. However, the low inheritance caused by the competition between host germ cells and the transferred ones is the most common complication and largely reduces the production efficiency in this way. Here, we generated a gene-edited chicken, in which germ cells can be ablated in a drug-dependent manner, as recipients for gene-edited PGC transfer. We used the nitroreductase/metronidazole (NTR/Mtz) system for cell ablation, in which NTR produces cytotoxic alkylating agents from administered Mtz, causing cell apoptosis. The chicken Vasa homolog (CVH) gene locus is used to drive the expression of the NTR gene in a germ cell-specific manner. In addition, a fluorescent protein gene, mCherry, was also placed in the CVH locus to visualize the PGCs. We named this system germ cell-Specific AutonoMoUs RemovAl Induction (gSAMURAI). gSAMURAI chickens will be an ideal recipient to produce offspring derived from transplanted exogenous germ cells.

bioengineering↗

bioRxiv2023

Deformable Cell-Like Microlasers for Real-Time Mechanical Quantification in Organoids

Mechanical stress in multicellular environments plays a critical role in a wide range of tissue function and drug delivery. However, conventional methods are incapable of quantifying internal solid stress in situ, which is the hallmark of the 3D multicellular mechanical environment. To overcome the limitations, here we developed hollow-core structured microsphere lasers to realize all-optical direct recording of cellular stress in organoids and spheroids with cellular resolution. The deformations of whispering-gallery-mode laser can therefore be transduced into the change of the laser spectrum to reflect deformation within two-hundred nanometers in deep tissue environment. Our findings demonstrate the capability to quantify internal solid stress in different types of human tumor spheroids in real time. We also explored its potential in mechano-responded drug screening. Dynamic monitoring of contractile stress inside human embryonic stem cell-derived cardiac organoids was also obtained. This method may bring new opportunities to mechanobiology with multicellular resolution and accelerate high-throughput drug screening in human organoids.

bioengineering↗

bioRxiv2023

Contributions of early and mid-level visual cortex to high-level object categorization

The complexity of visual features for which neurons are tuned increases from early to late stages of the ventral visual stream. Thus, the standard hypothesis is that high-level functions like object categorization are primarily mediated by higher visual areas because they require more complex image formats that are not evident in early visual processing stages. However, human observers can categorize images as objects or animals or as big or small even when the images preserve only some low- and mid-level features but are rendered unidentifiable ( texforms, Long et al., 2018). This observation suggests that even the early visual cortex, in which neurons respond to simple stimulus features, may already encode signals about these more abstract high-level categorical distinctions. We tested this hypothesis by recording from populations of neurons in early and mid-level visual cortical areas while rhesus monkeys viewed texforms and their unaltered source stimuli (simultaneous recordings from areas V1 and V4 in one animal and separate recordings from V1 and V4 in two others). Using recordings from a few dozen neurons, we could decode the real-world size and animacy of both unaltered images and texforms. Furthermore, this neural decoding accuracy across stimuli was related to the ability of human observers to categorize texforms by real-world size and animacy. Our results demonstrate that neuronal populations early in the visual hierarchy contain signals useful for higher-level object perception and suggest that the responses of early visual areas to simple stimulus features display preliminary untangling of higher-level distinctions.

neuroscience↗

bioRxiv2023

Cynipid wasps systematically reprogram host metabolism and restructure cell walls in developing galls

Many insects have evolved the ability to manipulate plant growth to generate extraordinary structures called galls in which insect larva can develop while being sheltered within and feeding on the plant. In particular, Cynipid (Hymenoptera: Cynipidae) wasps have evolved to form some of the most morphologically complex galls known and generate an astonishing array of gall shapes, colors, and sizes. However, the biochemical basis underlying these remarkable cellular and developmental transformations remains poorly understood. A key determinant in plant cellular development is the deposition of the cell wall to dictate the physical form and physiological function of newly developing cells, tissues, and organs. However, it is unclear to what degree cell walls are restructured to initiate and support the formation of new gall tissue. Here, we characterize the molecular alterations underlying gall development using a combination of metabolomic, histological, and biochemical techniques to elucidate how leaf cells are reprogrammed to form galls. Strikingly, gall development involves an exceptionally coordinated spatial deposition of lignin and xylan to form de novo gall vasculature. Our results highlight how Cynipid wasps can radically change the metabolite profile and restructure the cell wall to enable the formation of galls, providing new insights into the mechanism of gall induction and the extent to which plants can be entirely reprogrammed to form novel structures and organs.

plant biology↗

bioRxiv2023

Extended regulation interface coupled to the allosteric network and disease mutations in the PP2A-B56 delta holoenzyme

An increasing number of mutations associated with devastating human diseases are diagnosed by whole-genome/exon sequencing. Recurrent de novo missense mutations have been discovered in B56{delta} (encoded by PPP2R5D), a regulatory subunit of protein phosphatase 2A (PP2A), that cause intellectual disabilities (ID), macrocephaly, Parkinsonism, and a broad range of neurological symptoms. Single-particle cryo-EM structures show that the PP2A-B56{delta} holoenzyme possesses closed latent and open active forms. In the closed form, the long, disordered arms of B56{delta} termini fold against each other and the holoenzyme core, establishing dual autoinhibition of the phosphatase active site and the substrate-binding protein groove. The resulting interface spans over 190 [A] and harbors unfavorable contacts, activation phosphorylation sites, and nearly all residues with ID-associated mutations. Our studies suggest that this dynamic interface is close to an allosteric network responsive to activation phosphorylation and altered globally by mutations. Furthermore, we found that ID mutations perturb the activation phosphorylation rates, and the severe variants significantly increase the mitotic duration and error rates compared to the wild variant.

biochemistry↗

bioRxiv2023

Mode-based morphometry: A multiscale approach to mapping human neuroanatomy

Voxel-based morphometry (VBM) and surface-based morphometry (SBM) are two widely used neuroimaging techniques for investigating brain anatomy. These techniques rely on statistical inferences at individual points (voxels or vertices), clusters of points, or a priori regions-of-interest. They are powerful tools for describing brain anatomy, but offer little insights into the generative processes that shape a particular set of findings. Moreover, they are restricted to a single spatial resolution scale, precluding the opportunity to distinguish anatomical variations that are expressed across multiple scales. Drawing on concepts from classical physics, here we develop an approach, called mode-based morphometry (MBM), that can describe any empirical map of anatomical variations in terms of the fundamental, resonant modes--eigenmodes--of brain anatomy, each tied to a specific spatial scale. Hence, MBM naturally yields a multiscale characterization of the empirical map, affording new opportunities for investigating the spatial frequency content of neuroanatomical variability. Using simulated and empirical data, we show that the validity and reliability of MBM are either comparable or superior to classical vertex-based SBM for capturing differences in cortical thickness maps between two experimental groups. Our approach thus offers a robust, accurate, and informative method for characterizing empirical maps of neuroanatomical variability that can be directly linked to a generative physical process.

neuroscience↗

bioRxiv2023

Vaccinia virus induces EMT-like transformation and RhoA-mediated mesenchymal migration

The emerging outbreak of monkeypox is closely associated with the viral infection and spreading, threatening global public health. Virus-induced cell migration facilitates viral transmission. However, high-resolution dynamics and mechanisms underlying this type of cell migration remain unclear. Here, we investigate the motility of cells infected by vaccinia virus (VACV), a close relative of monkeypox, through combining multi-omics analyses and high-resolution live-cell imaging. We find that, upon VACV infection, the epithelial cells undergo EMT-like transformation, during which they lose intercellular junctions and acquire the migratory capacity to promote viral spreading. After transformation, VACV-induced mesenchymal migration is highly dependent on the actin cytoskeleton and RhoA signaling, which is responsible for the depolymerization of robust actin stress fibers, the leading-edge protrusion formation, and the rear-edge recontraction. Our study reveals how poxviruses alter the epithelial phenotype and regulate RhoA signaling to induce fast migration, providing a unique perspective to understand the pathogenesis of poxviruses.

cell biology↗

bioRxiv2023

Using single-cell RNA sequencing to generate cell-type-specific split-GAL4 reagents throughout development

Cell-type-specific tools facilitate the identification and functional characterization of distinct cell types, which underly the complexity of neuronal circuits. A large collection of existing genetic tools in Drosophila relies on enhancer activity to label different subsets of cells. These enhancer-based GAL4 lines often fail to show a predicable expression pattern to reflect the expression of nearby gene(s), partly due to an incomplete capture of the full gene regulatory elements. While genetic intersectional technique such as the split-GAL4 system further improve cell-type-specificity, it requires significant time and resource to generate and screen through combinations of enhancer expression patterns. In addition, since existing enhancer-based split-GAL4 lines that show cell-type-specific labeling in adult are not necessarily active nor specific in early development, there is a relative lack of tools for the study of neural development. Here, we use an existing single-cell RNA sequencing (scRNAseq) dataset to select gene pairs and provide an efficient pipeline to generate cell-type-specific split-GAL4 lines based on the native genetic regulatory elements. These gene-specific split-GAL4 lines can be generated from a large collection of coding intronic MiMIC/CRIMIC lines either by embryo injection or in vivo cassette swapping crosses and/or CRISPR knock-in at the N or C terminal of the gene. We use the developing Drosophila visual system as a model to demonstrate the high prediction power of scRNAseq-guided gene specific split-GAL4 lines in targeting known cell types. The toolkit allows efficient cluster annotation in scRNAseq datasets but also the identification of novel cell types. Lastly, the gene-specific split-GAL4 lines are broadly applicable to Drosophila tissues. Our work opens new avenues for generating cell-type-specific tools for the targeted manipulation of distinct cell types throughout development and represents a valuable resource to the fly research community. Significance StatementUnderstanding the functional role of individual cell types in the nervous systems has remained a major challenge for neuroscience researchers, partly due to incomplete identification and characterization of underlying cell types. To study the development of individual cell types and their functional roles in health and disease, experimental access to a specific cell type is often a prerequisite. Here, we establish an experimental pipeline to generate gene-specific split-GAL4 guided by single-cell RNA sequencing datasets. These lines show high accuracy for labeling targeted cell types from early developmental stages to adulthood and can be applied to any tissues in Drosophila. The collection of gene-speicifc-split-GAL4 will provide a valuable resource to the entire fly research community.

developmental biology↗

bioRxiv2023

Pancreatic Deletion of Mitogen-inducible Gene 6 Promotes Beta Cell Proliferation Following Destruction

Type 1 Diabetes (T1D) is caused by autoimmune-mediated beta cell destruction. Following beta cell injury, the pancreas attempts to launch a cellular repair and regenerative program, yet it fails to completely restore functional beta cell mass. One component of this regenerative program is epidermal growth factor receptor (EGFR) signaling. However, upon irreparable beta cell damage, EGFR signaling is dampened, disrupting attempts to restore functional beta cell mass and maintain normoglycemia. We previously demonstrated that the negative feedback inhibitor of EGFR, Mitogen-inducible gene 6 (Mig6), is induced by the pro-inflammatory cytokines central to the autoimmune-mediated beta cell destruction. We also established that pro-inflammatory cytokines suppress EGFR activation, and siRNA-mediated suppression of Mig6 restores EGFR signaling. Thus, we hypothesized that pro-inflammatory cytokines induce nitric oxide production and that in turn induced Mig6, disrupting EGFR repair mechanisms. We determined that NO induces Mig6, attenuating EGFR signaling, and NO synthase inhibition blocks the cytokine-mediated induction of Mig6, thereby restoring cytokine-impaired EGFR signaling. To that end, we treated mice lacking pancreatic Mig6 and control mice with a streptozotocin (STZ) to induce beta cell death and diabetes in a way that mimics the onset and progression of T1D. Whereas STZ-treated control mice became hyperglycemic and had reduced beta cell mass, STZ-treated Mig6 pancreas-specific knock out (PKO) mice remained euglycemic and glucose tolerant due to preserved beta cell mass. The restoration of beta cell mass in PKO mice was accompanied by enhanced beta cell proliferation. Thus, our work suggests that Mig6 is a promising target to preserve beta cell mass before overt T1D.

cell biology↗

bioRxiv2022

Aldo-Keto Reductase Family 1 Member A1 (AKR1A1) Deficiency Exacerbates Alcohol-Induced Hepatic Oxidative Stress, Inflammation, Steatosis, and Fibrosis

BackgroundAlcohol-associated liver disease (ALD) covers a wide range of hepatic lesions that depend on the amount and duration of alcohol consumption, from early and reversible conditions to hepatic steatosis and severe lesions, including steatohepatitis and alcoholic fibrosis, to irreversible cirrhosis. AKR1A1, an aldo-keto reductase family member, participates in the detoxification of alcohol-derived acetaldehyde, but its role in ALD remains unclear. In this study, we studied the role of AKR1A1 in the development of ALD using Akr1a1-/- knockout mice and palmitic acid/oleic acid (P/O) plus ethanol-treated AML12 hepatocyte cells. MethodsLevels of AKR1A1 were measured in mice fed with the Lieber-DeCarli diet containing 5% alcohol (alcohol-fed, AF) or control liquid diet (pair-fed, PF). The effects of AKR1A1 on the liver function, inflammation, oxidative stress, lipid accumulation, and fibrosis were assessed in AF-induced Akr1a1-/- and ICR control mice. ResultsData showed that AF-Akr1a1-/- mice exhibited an exacerbation of liver injury and increased gene and protein levels of inflammatory mediators, oxidative stress, lipid accumulation, and fibrosis, whilst decreased expression of antioxidant enzymes in their livers than the AF-ICR mice. Therefore, loss of AKR1A1 can activate 4-HNE/p53 signaling to modulate ROS and antioxidant balance, increase lipid peroxidation, fatty acid synthesis and lipid droplet formation, reduced fatty acid {beta}-oxidation, and elevated proinflammatory and fibrotic mediator, eventually exacerbate the ALD. In in vitro study, we further demonstrated that knockdown of Akrlal aggravated the effects of alcohol plus P/O-induced oxidative stress and steatosis, LPS-stimulated inflammation, and TGF-{beta}1-induced fibrosis in AML12 hepatocyte cells. Conclusionour results revealed that AKR1A1 exerts protective effects on alcohol-induced liver injury, steatosis, and fibrosis, possibly by regulating the 4-HNE-p53 signaling pathway.

pathology↗

bioRxiv2022

Aging Fly Cell Atlas Identifies Exhaustive Aging Features at Cellular Resolution

Aging is characterized by a decline in tissue function, but the underlying changes at cellular resolution across the organism remain unclear. Here, we present the Aging Fly Cell Atlas, a single-nucleus transcriptomic map of the whole aging Drosophila. We characterize 163 distinct cell types and perform an in-depth analysis of changes in tissue cell composition, gene expression, and cell identities. We further develop aging clock models to predict the fly age and show that ribosomal gene expression is a conserved predictive factor for age. Combining all aging features, we find unique cell type-specific aging patterns. This atlas provides a valuable resource for studying fundamental principles of aging in complex organisms.

developmental biology↗

bioRxiv2022

Microsecond pulse electrical stimulation modulates cell migration

Wound healing is a complicated process for maintaining skin integrity after injury, for which electrical stimulations (ES) are ascribed to promote wound healing by facilitating cell migration. Time-shortening of the stimulation treatment from current hours to minutes for efficient wound healing but free of cell damage in return, is however rather a challenge. Here, a novel mechanism of ultrashort pulse electric field (PEF), microsecond PEF at higher voltage, is proposed and realized to promote wound healing under a much short time (seconds) for the total treatment. We revealed that microsecond PEF regulated actin cytoskeleton reorganization and focal adhesion turnover, promoting fibroblasts migration in 2D cell cultures under the pulse stimulation. This accelerated fibroblast migration was accompanied by the mutual promotion with extracellular matrix (ECM) alignment in 3D microenvironments, which cooperatively benefit the eventual wound healing, and these findings were further confirmed by the enhanced skin wound healing in a classic mouse model. Additionally, we coined an actin- and collagen-dependent mechanism of microsecond PEF-mediated wound healing. The quantitative mechanism proposed here for our novel microsecond pulse electric filed (sPEF) methodology orients the new practical electric treatment in a wide range of biomedical applications, such as wound healing, regenerative medicine, and tissue engineering.

bioengineering↗

bioRxiv2022

Deletion of carboxypeptidase E in beta cells disrupts proinsulin processing and alters beta cell identity in mice

Carboxypeptidase E (CPE) facilitates the conversion of prohormones into mature hormones and is highly expressed in multiple neuroendocrine tissues. Carriers of CPE mutations have elevated plasma proinsulin and develop severe obesity and hyperglycemia. We aimed to determine whether loss of Cpe in pancreatic beta cells disrupts proinsulin processing and accelerates development of diabetes and obesity in mice. Pancreatic beta cell-specific Cpe knockout mice ({beta}CpeKO; Cpefl/fl x Ins1Cre/+) lack mature insulin granules and have elevated proinsulin in plasma; however, glucose-and KCl-stimulated insulin secretion in {beta}CpeKO islets remained intact. High fat diet-fed {beta}CpeKO mice showed comparable weight gain and glucose tolerance compared to Wt littermates. Notably, beta-cell area was increased in chow-fed {beta}CpeKO mice and beta-cell replication was elevated in {beta}CpeKO islets. Transcriptomic analysis of {beta}CpeKO beta cells revealed elevated glycolysis and Hif1-target gene expression. Upon high glucose challenge, beta cells from {beta}CpeKO mice showed reduced mitochondrial membrane potential, increased reactive oxygen species, reduced MafA, and elevated Aldh1a3 transcript levels. Following multiple low-dose streptozotocin treatment, {beta}CpeKO mice had accelerated hyperglycemia with reduced beta-cell insulin and Glut2 expression. These findings suggest that Cpe and proper proinsulin processing are critical in maintaining beta cell function during the development of diabetes.

physiology↗

bioRxiv2022

A single dose of intravenous human amniotic membrane-derived mesenchymal stem cells limits transmural infarction, reduces fibrosis size, and improves left ventricular systolic function in the myocardial ischemic/reperfusion model of rats

Despite the advances in coronary reperfusion in acute myocardial infarction (MI), post-MI heart failure is still a large burden of public health. Transmural infarction and extended fibrosis contribute largely to post-MI systolic dysfunction and heart failure, and thus cardioprotective strategies are crucial. Human amniotic membrane-derived mesenchymal stem cells (hAMSCs) have been shown with properties of immunomodulation, anti-inflammation, and low immunogenicity, which make them good candidates for cell therapies. In this study, a myocardial ischemia/reperfusion (I/R) model was established in rats, and hAMSCs were administered via the tail vein during coronary reperfusion. Compared to the control group, the rats receiving hAMSCs during the I/R procedure (hAMSC group) exhibited significantly better left ventricular ejection fractions after MI. Histological examinations of the hearts in hAMSC group showed minimal transmural infarction 4 weeks after the I/R procedure. Compared to the control group, hAMSC group had reduced size of cardiac fibrosis and less thinning of myocardial wall. In conclusion, intravenous hAMSCs limit transmural infarction, reduce fibrosis size, and improve left ventricular systolic function after MI in the animal model.

cell biology↗

bioRxiv2022

Insights into deuterostome evolution from the biphasic transcriptional programmes of hemichordates

Evolutionary history of deuterostomes remains unsolved and is intimately related to the origin of chordates. Among deuterostomes, hemichordates and echinoderms (collectively called Ambulacraria) are sister groups of chordates. Comparative studies involving these three groups provide valuable insights into deuterostome evolution. Indirect developing hemichordates produce planktonic larvae that bear resemblance to echinoderm larvae before undergoing metamorphosis into an adult body plan with anteroposterior polarity homologous to that of chordates. Therefore, understanding the developmental processes of indirect-developing hemichordates can help understand the evolution of deuterostomes and the origins of chordates. In this study, we analysed the transcriptomes and chromatin accessibility of multiple developmental stages of the indirect-developing hemichordate Ptychodera flava and discovered that it exhibits a biphasic developmental program controlled by distinct sets of transcription factors and their corresponding regulatory elements. Comparative analyses of transcriptomes and network analyses revealed that the gastrula transcriptome is relatively ancient, and the TFs orchestrating its gene expression are highly interconnected in networks of cis-regulatory interactions. Comparing the developmental transcriptomes of hemichordates, echinoderms, and amphioxus, revealed high conservation of gene expression during gastrulation that extends to the neurula stages of amphioxus, along with remarkable similarity in larval transcriptomes across the three species. Additionally, we show that P. flava possesses conserved interactions of transcription factors necessary for the development of echinoderm endomesoderm and chordate axial mesoderm, including conserved cis-regulatory elements of the FoxA transcription factor that is central to the two networks. These findings suggest the existence of a deuterostome phylotypic stage during gastrulation governed by gene regulatory networks with conserved cis-regulatory interactions. Conversely, integration of gene expression data with synteny data revealed that gene expression recapitulates the independent evolutionary history of the Ancestral Linkage Groups that underwent rearrangements in each deuterostome lineage, suggesting a potential role of genome rearrangement during the evolution of larval strategies in hemichordates and deuterostome body plans.

evolutionary biology↗

bioRxiv2022

Molecular insights into intrinsic transducer-coupling bias in the CXCR4-CXCR7 system

Chemokine receptors constitute an important subfamily of G protein-coupled receptors (GPCRs), and they are critically involved in a broad range of immune response mechanisms. Ligand promiscuity among these receptors makes them an interesting target to explore novel aspects of biased agonism. Here, we comprehensively characterize two chemokine receptors namely, CXCR4 and CXCR7, which share a common chemokine agonist (CXCL12), in terms of their G-protein coupling, {beta}-arrestin ({beta}arr) recruitment, contribution of GRKs, and ERK1/2 MAP kinase activation. We observe that CXCR7 lacks G-protein coupling while maintaining robust {beta}arr recruitment with a major contribution of GRK5/6. On the other hand, CXCR4 displays robust G-protein activation as expected, however, it exhibits significantly reduced {beta}arr-coupling compared to CXCR7 in response to their shared natural agonist, CXCL12. These two receptors induce distinct {beta}arr conformations even when activated by the same agonist, and CXCR7, unlike CXCR4, fails to activate ERK1/2 MAP kinase. We further determine the crystal structure of {beta}arr2 in complex with a carboxyl-terminal phosphopeptide derived from CXCR7, which reveals a smaller interdomain rotation than observed previously for activated {beta}arrs. Importantly, structure-guided cellular experiments reveal a key contribution of a single phosphorylation site in CXCR7 on {beta}arr recruitment and endosomal trafficking. Taken together, our study provides molecular insights into intrinsic bias encoded in the CXCR4-CXCR7 system, and it has broad implications for therapeutically important framework of biased agonism.

biochemistry↗