Biology subjects

Lin, C.-W.

Publications and source records attributed to Lin, C.-W..

At least 19 recordsLinked to original sources

bioRxiv2026

An On-Demand Nanodisc Platform for Reconstitution of Functional Membrane Proteins into Model and Living Membranes

Membrane proteins are central to transport, signaling, and pharmacological regulation, yet their direct functional reconstitution into defined membrane environments remains technically challenging. Detergent-based workflows have enabled major advances in membrane protein research, but some applications require complementary strategies that better preserve native-like lipid environments. Cell-based expression approaches, meanwhile, require long incubation times and suffer from cell-type-dependent variability. Here, we establish nanodiscs as modular carriers for the rapid delivery of both lipids and full-length membrane proteins into model and cellular membranes. Using supported lipid bilayers, we first show that membrane scaffold protein (MSP) nanodiscs mediate efficient lipid transfer within minutes, with fluorescence recovery after photobleaching confirming lateral mobility of the delivered lipids. We then extend this strategy to the bacterial calcium channel BsYetJ, achieving concentration-dependent protein incorporation and single-molecule diffusion within supported lipid bilayers. Importantly, BsYetJ-loaded nanodiscs enable direct reconstitution of functional channels into intact mammalian plasma membranes across multiple cell lines. Calcium imaging demonstrates robust BsYetJ-mediated calcium influx, confirming that the delivered channel retains ion-conductive activity after transfer into heterologous cellular membranes. Crucially, this nanodisc-mediated delivery bypasses the variable trafficking pathways inherent to different host systems, allowing for the direct reconstitution of membrane proteins into target membranes while preserving their functional activity. Furthermore, unlike MSP nanodiscs, styrene-maleic acid (SMA) nanodiscs can directly capture membrane proteins from native cell membranes. This capability makes them particularly well-suited for studying complex and challenging membrane proteins. Therefore, we further generalize this platform using SMA nanodiscs . We demonstrate that, similar to MSP nanodiscs, SMA nanodiscs can efficiently deliver lipid cargo to supported bilayers and mammalian cells. By directly capturing full-length dopamine D2 receptor from cellular membranes and transferring it into naive target cells, we achieve functional GPCR reconstitution, as validated by specific binding of a custom fluorescent agonist. Together, these results demonstrate that nanodiscs can serve not only as stabilizing membrane mimetics but also as active delivery vehicles for on-demand membrane protein reconstitution. This approach provides a rapid and broadly applicable platform for interrogating ion channels, GPCRs, and other challenging pharmacological targets in user-defined membrane environments.

biochemistry↗

bioRxiv2026

High resolution spatial transcriptomic and proteomic profiling of early primate gastrulation in utero

Early gastrulation represents a key stage in which several embryonic and extra-embryonic lineages are formed in the primitive streak to support embryonic development. However, very little is known about lineage specification events in the early primate gastrula. To gain molecular insights into mechanisms that organize this stage of primate development, we performed high-resolution spatial transcript and protein expression profiling of five sagittal sections from a cynomolgus macaque embryo at Carnegie Stage 6b, an early gastrulation stage. We established a molecular map of six major cell populations: the epiblast, primitive streak, amnion, endoderm, mesoderm, and primordial germ cells. We also uncovered a variety of lineage subtypes, as well as important signaling and transcriptional networks. In particular, we show that canonical WNT signaling is a driver of amnion fate progression. Together, this study provides a unique multiomic resource of an early primate gastrula with complete spatial information for future investigations.

developmental biology↗

bioRxiv2026

Nanodisc-Mediated Visualization of Crowding-Induced Condensation and Membrane Reorganization in Two-Dimensional Membrane Environments

Although biological membranes exhibit complex and dynamic organization, the mechanistic role of molecular crowding in governing lateral membrane heterogeneity remains poorly characterized experimentally. Here, we provide direct experimental visualization showing that crowding-induced condensation of membrane-anchored macromolecules above the bilayer interface reorganizes membrane dynamics and gives rise to spatially heterogeneous lipid mobility. Both PEGylated lipids and membrane-anchored proteins undergo surface-density-driven condensation on supported lipid bilayers, forming immobile regions that constrain lipid diffusion. Notably, the condensation threshold varies inversely with PEG chain length and surface density, defining a quantitative relationship between molecular size and crowding strength. To directly visualize these crowding-induced structures, we employed nanodelivery using lipid-loaded nanodiscs, revealing a clear correspondence between condensed crowder regions and diffusion barriers reminiscent of the picket-fence model of live-cell membranes. Similar condensation behavior observed for protein-crowded SLBs demonstrates the generality of this crowding-driven mechanism. Together, these findings establish surface-density-driven crowding and condensation of membrane-anchored macromolecules as a key physical mechanism underlying lateral membrane inhomogeneity and position nanodelivery as a general approach for interrogating membrane organization across synthetic and biological systems.

biophysics↗

bioRxiv2025

Comparative gene regulatory network mapping of Brassicaceae members with differential drought tolerance

Climate change is projected to intensify weather extremes like droughts that threaten global crop yields. While many crops are sensitive to water deprivation, they have drought-tolerant wild relatives; however, the molecular basis for this differential tolerance among closely related species remains unclear. We previously investigated this using transcriptomics in the Brassicaceae family, comparing the drought-sensitive reference plant Arabidopsis thaliana (Ath) with its drought-tolerant relatives Arabidopsis lyrata (Aly) and Eutrema salsugineum (Esa), uncovering key differences that may underlie their respective phenotypes. Here, to elucidate the regulatory architecture driving these differences, we mapped drought-responsive gene regulatory networks (GRNs) for all three species using the yeast one-hybrid (Y1H) approach. We cloned promoters of orthologs with divergent drought-induced expression patterns and screened them against the Ath transcription factor (TF) collection, generating a quality-controlled cross-species drought-responsive GRN map encompassing 1,137 high-confidence TF-promoter interactions. Comparative analysis revealed that the tolerant species share greater regulatory similarity and exhibit higher network connectivity than Ath. An Esa-specific expansion of bZIP TF interactions was observed, consistent with an enrichment of G-box motifs in its genome and in drought-upregulated genes. Several observed changes affect the ABA signalling pathway: Ath gained a susceptibility linked GBF3-CYP707A1 edge, whereas Esa acquired tolerance associated ABF-mTERF10 interactions. Furthermore, network-rewiring analysis uncovered a novel role for ASIL2 in stress response. Finally, our network highlights TFs (CSDP1, ERF4, HB6, and MYB73) that likely contribute to the "stress-primed" state of Aly and Esa. Our work provides a broadly applicable framework for comparative GRN mapping and a valuable resource for improving drought tolerance in crops.

plant biology↗

bioRxiv2025

The natural diversity of E. coli transporter-dependent capsules

Serotyping of bacteria using genomic information (in silico serotyping) has increasingly replaced serology. However, the E. coli capsule serotyping system has been largely abandoned since the 1990s, leaving gaps in our knowledge of capsule genetics, diversity, distribution, and epidemiology. To address this, we established a definitive genotype-serotype map for 35 serologically identified and structurally characterized transporter-dependent capsules. We then surveyed >37,000 E. coli genomes, cataloging 85 transporter-dependent capsule types (K-types), including 55 novel ones. We leveraged this catalog to develop an in silico serotyping tool, kTYPr, and applied it to curated sets of >25,000 E. coli genomes and metagenome-assembled genomes spanning diverse environmental and clinical sources. We found novel K-types enriched in under-sampled environments and associated with E. coli disease. This research expands our understanding of E. coli surface structures, supporting efforts for precision targeting with phage therapy or vaccines.

microbiology↗

bioRxiv2025

The endo-lysosomal system drives lumen formation in a human epiblast model

The formation of a central lumen in the epiblast is a critical step that occurs during implantation in the human embryo. Lumen formation is accompanied by highly dynamic and complex cargo trafficking in the endo-lysosomal system. However, our understanding of key players and machineries that control this critical trafficking process remains incomplete in the context of epiblast development. Here, we explored endo-lysosomal dynamics that are associated with the generation of the apicosome, the earliest stage of lumen formation in a model of human epiblast development based on human pluripotent stem cells. We uncovered a hybrid early/late endosome compartment as well as a previously unrecognized dynamics of late endosome and lysosome compartments in trafficking podocalyxin (PODXL), a sialomucin glycoprotein that helps to establish and maintain the open lumen, during apicosome formation. To gain molecular insight into these unique hybrid endosome and late endosome/lysosome machineries in PODXL traffic, we used APEX2-based spatial proteomics to identify PODXL-proximity partners during apicosome formation, and identified RAB35, a Rab small GTPase known to control PODXL traffic as well as early and late endosome dynamics, as a key player in controlling apicosome formation. Our results suggest that RAB35 limits excess apicosome formation by promoting the early to late endosome transition as well as lysosome formation, which help to reduce PODXL to a level necessary for single apicosome formation. Overall, this study reveals novel endo-lysosomal mechanisms that contribute to apical membrane morphogenesis in a human model of epiblast formation.

developmental biology↗

bioRxiv2025

CaV1.2-dependent excitation-transcription coupling modulates nociception

Peripheral nociceptive sensory neurons integrate various noxious inputs, resulting in local depolarization that triggers the firing of action potentials and thus the sensation of pain. We recently reported that nociceptor depolarization itself initiates signaling by the calcium channel Cav1.2 causing acute hyperalgesia in vivo. However, whether this mechanism initiates excitation-transcription (E-T) coupling and thereby leads to long-lasting modulation of nociceptor activity remains poorly understood. Using high content imaging of dorsal root ganglion (DRG) neurons, we here found that depolarization of nociceptors induces phosphorylation of the transcription factor (TF) cAMP-response element binding protein (CREB), which was affected by inhibition of protein kinase A (PKA) and calcineurin, but not Ca2+/calmodulin-dependent protein kinases. Genetic deletion or pharmacological inhibition of Cav1.2 confirmed its role in calcium-dependent kinase signaling and CREB phosphorylation after depolarization. In line with this, pharmacological modulation of Cav1 channels affected the expression of a subset of depolarization-regulated immediate early genes known to orchestrate a broader transcriptional response. Indeed, RNA-Seq analysis of DRG neurons from mice with a tissue-specific deletion of Cav1.2 in nociceptive sensory neurons (SNS-Cacna1c-/- mice) revealed downregulation of multiple calcium and potassium channel subunits as well as proteins involved in synaptic vesicle release and cell adhesion. Furthermore, repetitive firing of action potentials and release of the neuropeptide CGRP was impaired in Cav1.2-deficient sensory neurons. SNS-Cacna1c-/- mice showed increased sensitivity to noxious heat and exacerbated inflammatory but not neuropathic pain. In conclusion, our data suggest a Cav1.2-dependent E-T coupling mechanism in nociceptors that counteracts nociception in vivo. HighlightsO_LIDepolarization induces Cav1.2- and PKA-dependent phosphorylation of the transcriptional regulator CREB in nociceptors C_LIO_LICav1.2 regulates the expression of depolarization-induced immediate early genes and induces reorganization of the signaling network in nociceptors C_LIO_LICav1.2-deficient nociceptors downregulate multiple ion channel subunits as well as proteins involved in synaptic vesicle release and cell adhesion C_LIO_LICav1.2-deficient nociceptors show impaired depolarization-induced PKA-II signaling, CREB phosphorylation, repetitive firing of action potentials, and release of the neuropeptide CGRP C_LIO_LINociceptor-specific Cav1.2-deficiency in mice increases the sensitivity to noxious heat and exacerbates inflammatory pain C_LI In briefIsensee et al. report that depolarization of nociceptors induces calcium influx through Cav1.2 channels, thereby initiating a signaling cascade that links neuronal excitation to transcriptional regulation of immediate early genes (E-T coupling). Nociceptor-specific knockout of Cav1.2 led to transcriptional changes in nociceptor-specific genes and was associated with impaired depolarization-induced signaling, action potential firing, and neuropeptide release. As the Cav1.2-deficient mice show increased noxious heat sensitivity and exacerbated inflammatory pain, these findings suggest that Cav1.2-dependent E-T coupling mechanism counteracts nociception in vivo.

neuroscience↗

bioRxiv2024

Severe traumatic brain injury temporally affects cerebral blood flow, endothelial cell phenotype, and cilia

BackgroundPrevious clinical work suggested that altered cerebral blood flow (CBF) in severe traumatic brain injury (sTBI) correlates with poor executive function and clinical outcome. However, the molecular consequences of altered CBF on endothelial cells (ECs) and their blood flow-sensor organelle called cilia are not known. MethodsWe performed laser speckle contrast imaging, single cell isolation, and single cell RNA sequencing (scRNAseq) after sTBI in a closed skull, linear impact mouse model. Validation of select ciliary target protein changes was performed using flow cytometry. Additionally, in vitro experiments modeled the post-injury hypoxic environment to evaluate the effect on cilia protein ARL13B in human brain microvascular ECs. ResultsWe detected immediate reductions in CBF that were sustained for at least 100 minutes in both impacted and non-impacted sides of the brain. Our scRNAseq data detected heterogeneity in the brain cortex-derived EC cluster and demonstrated that two of five unique EC sub-clusters changed their relative proportions post-sTBI. Consistent with flow changes, we identified multiple genes associated with the fluid shear stress pathway that were significantly differentially expressed in brain ECs post-injury. Also, ECs displayed activation of ischemic pathway as early as day 1 post-injury, and enrichment of hypoxia pathway at day 7 and 28 post- injury. Arl13b ciliary gene expression was lost on day 1 in ECs cluster and remained lost for the entire course of the injury. We validated the loss of cilia protein ARL13B specifically from brain ECs as early as day 1 post-injury and detected the protein in the peripheral blood of the injured mice. We also determined that hypoxia could induce loss of ARL13B protein from cultured ECs. ConclusionsIn severe TBI, blood flow is disrupted in both impacted and non-impacted regions of the brain, creating a hypoxic environment that may influence ciliary gene and protein expression on ECs.

neuroscience↗

bioRxiv2024

Grb2 Phosphorylation Antagonizes EGFR-driven Ras Activation by Interfering with Condensate Assembly

Upon ligand binding, the kinase domain of EGFR phosphorylates multiple tyrosine residues on the receptor cytoplasmic tail through a trans-autophosphorylation process. Phosphotyrosine sites on activated receptors recruit Grb2, which further recruits SOS to initiate downstream signaling by activating Ras. Multivalent binding between SOS and Grb2, as well as direct Grb2:Grb2 interactions, contribute to formation of a protein condensate of activated EGFR. The condensed state of EGFR facilitates autoinhibition release in SOS and exerts regulatory control over signal propagation from activated EGFR to Ras. While kinase activity of EGFR is an essential driver of this signaling process, phosphorylation at residue Y160 on Grb2 blocks Grb2:Grb2 binding and can interfere with EGFR condensation. Here, using a reconstituted system, we examine how titrating kinase activity in the EGFR system can both promote and inhibit signal output to Ras. The results reveal how effects of tyrosine kinase inhibition can, under some circumstances, promote Ras activation by inhibiting negative feedback through Grb2 phosphorylation and disruption of a Grb2 SH2/SH3 dimer interface. Statement of SignificanceActivated EGFR forms a biomolecular condensate, via linkage of multiple EGFR through Grb2 and SOS, and the condensation state of EGFR influences signal propagation to Ras. While tyrosine phosphorylation is a critical step in EGFR activation, phosphorylation of Grb2 can have an inhibitory effect on EGFR condensation and subsequent Ras activation. Under some conditions, kinase inhibition can promote signaling from EGFR to Ras.

biophysics↗

bioRxiv2024

Enzymatic reactions dictated by the 2D membrane environment

The cell membrane is a fundamental component of cellular architecture. Beyond serving as a physical barrier that encloses the cytosol, it also provides a crucial platform for numerous biochemical reactions. Due to the unique two-dimensional and fluidic environment of the membrane, reactions that occur on its surface are subject to specific physical constraints. However, the advantages and disadvantages of membrane-mediated reactions have yet to be thoroughly explored. In this study, we reconstitute a classic proteolytic cleavage reaction at the membrane interface, designed for the real-time, single-molecule kinetic analysis. The interactions between the enzyme and substrate near the membrane are examined under different classic scenarios. Our findings reveal that while the membrane environment significantly enhances enzymatic activity, it also imposes diffusion limitations that reduce this activity over time. By adjusting the enzymes membrane affinity to an intermediate level, we enable the enzyme to "hop" on the membrane surface, overcoming these diffusion constraints and sustaining high enzymatic activity with faster kinetics. These results provide critical insights into the role of the cell membrane in regulating biochemical reactions and can be broadly applied to other membrane-associated interactions.

biophysics↗

bioRxiv2023

A gut meta-interactome map reveals modulation of human immunity by microbiome effectors

The molecular mechanisms by which the gut microbiome influences human health remain largely unknown. Pseudomonadota is the third most abundant phylum in normal gut microbiomes. Several pathogens in this phylum can inject so-called virulence effector proteins into host cells. We report the identification of intact type 3 secretion systems (T3SS) in 5 - 20% of commensal Pseudomonadota in normal human gut microbiomes. To understand their functions, we experimentally generated a high-quality protein-protein meta-interactome map consisting of 1,263 interactions between 289 bacterial effectors and 430 human proteins. Effector targets are enriched for metabolic and immune functions and for genetic variation of microbiome-influenced traits including autoimmune diseases. We demonstrate that effectors modulate NF-{kappa}B signaling, cytokine secretion, and adhesion molecule expression. Finally, effectors are enriched in metagenomes of Crohns disease, but not ulcerative colitis patients pointing toward complex contributions to the etiology of inflammatory bowel diseases. Our results suggest that effector-host protein interactions are an important regulatory layer by which the microbiome impacts human health.

microbiology↗

bioRxiv2023

Identification of amnion progenitor-like cells at the amnion-epiblast boundary in the primate peri-gastrula

Amniogenesis is triggered in a collection of pluripotent epiblast cells as the human embryo implants. To gain insights into the critical but poorly understood transcriptional machinery governing amnion fate determination, we examined the evolving transcriptome of a developing human pluripotent stem cell-derived amnion model at the single cell level. This analysis revealed several continuous amniotic fate progressing states with state-specific markers, which include a previously unrecognized CLDN10+ amnion progenitor state. Strikingly, we found that expression of CLDN10 is restricted to the amnion-epiblast boundary region in the human post-implantation amniotic sac model as well as in a peri-gastrula cynomolgus macaque embryo, bolstering the growing notion that, at this stage, the amnion-epiblast boundary is a site of active amniogenesis. Bioinformatic analysis of published primate peri-gastrula single cell sequencing data further confirmed that CLDN10 is expressed in cells progressing to amnion. Additionally, our loss of function analysis shows that CLDN10 promotes amniotic but suppresses primordial germ cell-like fate. Overall, this study presents a comprehensive amniogenic single cell transcriptomic resource and identifies a previously unrecognized CLDN10+ amnion progenitor population at the amnion-epiblast boundary of the primate peri-gastrula.

developmental biology↗

bioRxiv2023

Surface crosslinking of virus-like particles increases resistance to proteases, low pH and mechanical stress for mucosal applications

AbstractVirus-like particles (VLPs) are emerging as nano-scaffolds in a variety of biomedical applications including the delivery of vaccine antigens to mucosal surfaces. These soft, colloidal, and proteinaceous structures (capsids) are nevertheless susceptible to mucosal environmental factors which limit their usefulness. We addressed this issue by crosslinking multiple capsid surface reactive residues using polyethylene glycol tethers. Surface crosslinking enhanced the colloidal stability and mechanical strength of VLPs against low pH, proteases, and mechanical agitation, while it did not interfere with function as vaccine. Chemical crosslinking thus offers a viable means to enhance the resilience of VLPs in mucosal applications.

biophysics↗

bioRxiv2023

Temporally resolved early BMP-driven transcriptional cascade during human amnion specification

Amniogenesis, a process critical for continuation of healthy pregnancy, is triggered in a collection of pluripotent epiblast cells as the human embryo implants. Previous studies have established that BMP signaling is a major driver of this lineage specifying process, but the downstream BMP-dependent transcriptional networks that lead to successful amniogenesis remain to be identified. This is, in part, due to the current lack of a robust and reproducible model system that enables mechanistic investigations exclusively into amniogenesis. Here, we developed an improved model of early amnion specification, using a human pluripotent stem cell-based platform in which the activation of BMP signaling is controlled and synchronous. Uniform amniogenesis is seen within 48 hours after BMP activation, and the resulting cells share transcriptomic characteristics with amnion cells of a gastrulating human embryo. Using detailed time-course transcriptomic analyses, we established a previously uncharacterized BMP-dependent amniotic transcriptional cascade, and identified markers that represent five distinct stages of amnion fate specification; the expression of selected markers was validated in early post-implantation macaque embryos. Moreover, a cohort of factors that could potentially control specific stages of amniogenesis was identified, including the transcription factor TFAP2A. Functionally, we determined that, once amniogenesis is triggered by the BMP pathway, TFAP2A controls the progression of amniogenesis. This work presents a temporally resolved transcriptomic resource for several previously uncharacterized amniogenesis states and demonstrates a critical intermediate role for TFAP2A during amnion fate specification.

developmental biology↗

bioRxiv2021

A two-component protein condensate of EGFR and Grb2 regulates Ras activation at the membrane

We reconstitute a phosphotyrosine-mediated protein condensation phase transition of the [~]200 residue cytoplasmic tail of the epidermal growth factor receptor (EGFR) and the adaptor protein, Grb2, on a membrane surface. The phase transition depends on phosphorylation of the EGFR tail, which recruits Grb2, and the dimerization of Grb2, which provides the crosslinking element for condensation with EGFR. The Grb2 Y160 residue plays a structurally critical role in dimer formation, and phosphorylation or mutation of Y160 prevents EGFR:Grb2 condensation. By extending the reconstitution experiment to include the guanine nucleotide exchange factor, SOS, and its substrate Ras, we further find that EGFR condensation controls the ability of SOS to activate Ras. These results identify an EGFR:Grb2 protein condensation phase transition as a regulator of signal propagation from EGFR to the MAPK pathway.

biophysics↗

bioRxiv2021

A map of direct SARS-CoV-2 protein interactions implicates specific human host processes

Key steps in viral propagation, immune suppression, and pathology are mediated by direct, binary, physical interactions between viral and host proteins. To understand the biology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we generated an unbiased systematic map of binary interactions between viral and host proteins, complementing previous co-complex association maps by conveying more direct mechanistic understanding and potentially enabling targeted disruption of direct interactions. To this end, we deployed two parallel strategies, identifying 205 virus-host and 27 intraviral binary interactions amongst 171 host and 19 viral proteins, and confirming high quality of these interactions via a calibrated orthogonal assay. Host proteins interacting with SARS-CoV-2 proteins are enriched in various cellular processes, including immune signaling and inflammation, protein ubiquitination, and membrane trafficking. Specific subnetworks provide new hypotheses related to viral modulation of host protein homeostasis and T-cell regulation. The binary virus-host protein interactions we identified can now be prioritized as targets for therapeutic intervention. More generally, we provide a resource of systematic maps describing which SARS-CoV-2 and human proteins interact directly.

systems biology↗

bioRxiv2020

Glycan-Protein Interactions Determine Kinetics of N-Glycan Remodeling

A hallmark of N-linked glycosylation in the secretory compartments of eukaryotic cells is the sequential remodeling of an initially uniform oligosaccharide to a site-specific, heterogeneous ensemble of glycostructures on mature proteins. To understand site-specific processing, we used protein disulfide isomerase (PDI), a model protein with five glycosylation sites, for molecular dynamics (MD) simulations and compared the result to a biochemical in vitro analysis with four different glycan processing enzymes. As predicted by an analysis of the accessibility of the N-glycans for their processing enzymes derived from the MD simulations, N-glycans at different glycosylation sites showed different kinetic properties for the processing enzymes. In addition, altering the tertiary structure context of N-glycan substrates affected N-glycan remodeling in a site-specific way. We propose that differential, tertiary structure context dependent N-glycan reactivities lead to different glycan structures in the same protein through kinetically controlled processing pathways.

biochemistry↗

bioRxiv2020

Dihydroceramide desaturase directs the switch between exosome production and autophagy for neuronal maintenance

Exosomes are important for cell-cell communication. Deficiencies in the human dihydroceramide desaturase gene, DEGS1, increase the dihydroceramide-to-ceramide ratio and causes hypomyelinating leukodystrophy. However, the disease mechanism remains unknown. Here, we developed an in vivo assay with spatially controlled expression of exosome markers in Drosophila eye imaginal discs and showed that the level and activity of the DEGS1 ortholog, ifc, correlated with exosome production. Knocking out ifc decreased the density of the exosome precursor intraluminal vesicles (ILVs) in the multivesicular endosomes and reduced the number of exosomes released. While ifc overexpression and autophagy inhibition both enhanced exosome production, combining the two had no additive effect. Moreover, DEGS1 activity was sufficient to drive ILV formation in vitro. Together, DEGS1/Ifc controls the dihydroceramide-to-ceramide ration and enhances exosome secretion by promoting ILV formation and preventing the autophagic degradation of MVEs. These findings provide a potential cause for the neuropathy associated with DEGS1-deficient mutations. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/376046v3_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@c7479corg.highwire.dtl.DTLVardef@12e7f46org.highwire.dtl.DTLVardef@1a5e7f0org.highwire.dtl.DTLVardef@11e7f08_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIAn in vivo system was developed for observing exosome production in Drosophila. C_LIO_LIDihydroceramide desaturase (DEGS1/Ifc) promotes exosome production by two means. C_LIO_LIIfc drives membrane invagination to promote the formation of intraluminal vesicles. C_LIO_LIIfc inhibits autophagic degradation of MVEs and increases exosome release. C_LI eTOC BlurbThe level and activity of dihydroceramide desaturase (human DEGS1 and Drosophila Ifc) correlate with exosome production. Wu et al. show that DEGS1 drives the formation of intraluminal vesicles in vivo and in vitro. Overexpressing Ifc inhibits autophagy and reduces the degradation of multivesicular endosomes, thus increases exosome release.

cell biology↗