The Pho23-Rpd3 histone deacetylase complex regulates the yeast metabolic transcription factor Stb5.

Macroautophagy/autophagy is an essential catabolic process for maintaining homeostasis and cell survival under stressful conditions. We previously characterized the metabolic transcription factor Stb5 as a negative modulator of autophagy through its regulation of genes involved in NADPH production. However, the molecular mechanisms regulating STB5 expression are not fully characterized. Here, we identify the yeast Pho23-Rpd3 histone deacetylase complex as a transcriptional regulator of STB5 . Our work provides insight into the mechanisms modulating the metabolic transcription factor Stb5 and expands on the repertoire of genes targeted by the Pho23-Rpd3 complex.

The yeast transcription factor Stb5 acts as a negative regulator of autophagy by modulating cellular metabolism.

Macroautophagy/autophagy is a highly conserved pathway of cellular degradation and recycling that maintains cell health during homeostatic conditions and facilitates survival during stress. Aberrant cellular autophagy contributes to the pathogenesis of human diseases such as cancer, neurodegeneration, and cardiovascular, metabolic and lysosomal storage disorders. Despite decades of research, there remain unanswered questions as to how autophagy modulates cellular metabolism, and, conversely, how cellular metabolism affects autophagy activity. Here, we have identified the yeast metabolic transcription factor Stb5 as a negative regulator of autophagy. Chromosomal deletion of STB5 in the yeast Saccharomyces cerevisiae enhances autophagy. Loss of Stb5 results in the upregulation of select autophagy-related (ATG) transcripts under nutrient-replete conditions; however, the Stb5-mediated impact on autophagy occurs primarily through its effect on genes involved in NADPH production and the pentose phosphate pathway. This work provides insight into the intersection of Stb5 as a transcription factor that regulates both cellular metabolic responses and autophagy activity.Abbreviations: bp, base pairs; ChIP, chromatin immunoprecipitation; G6PD, glucose-6-phosphate dehydrogenase; GFP, green fluorescent protein; IDR, intrinsically disordered region; NAD, nicotinamide adenine dinucleotide; NADP+, nicotinamide adenine dinucleotide phosphate; NADPH, nicotinamide adenine dinucleotide phosphate (reduced); ORF, open reading frame; PA, protein A; PCR, polymerase chain reaction; PE, phosphatidylethanolamine; PPP, pentose phosphate pathway; prApe1, precursor aminopeptidase I; ROS, reactive oxygen species; RT-qPCR, real-time quantitative PCR; SD, standard deviation; TF, transcription factor; TOR, target of rapamycin; WT, wild-type.

SETD2 transcriptional control of ATG14L/S isoforms regulates autophagosome-lysosome fusion.

Macroautophagy/autophagy is an evolutionarily conserved and tightly regulated catabolic process involved in the maintenance of cellular homeostasis whose dysregulation is implicated in several pathological processes. Autophagy begins with the formation of phagophores that engulf cytoplasmic cargo and mature into double-membrane autophagosomes; the latter fuse with lysosomes/vacuoles for cargo degradation and recycling. Here, we report that yeast Set2, a histone lysine methyltransferase, and its mammalian homolog, SETD2, both act as positive transcriptional regulators of autophagy. However, whereas Set2 regulates the expression of several autophagy-related (Atg) genes upon nitrogen starvation, SETD2 effects in mammals were found to be more restricted. In fact, SETD2 appears to primarily regulate the differential expression of protein isoforms encoded by the ATG14 gene. SETD2 promotes the expression of a long ATG14 isoform, ATG14L, that contains an N-terminal cysteine repeats domain, essential for the efficient fusion of the autophagosome with the lysosome, that is absent in the short ATG14 isoform, ATG14S. Accordingly, SETD2 loss of function decreases autophagic flux, as well as the turnover of aggregation-prone proteins such as mutant HTT (huntingtin) leading to increased cellular toxicity. Hence, our findings bring evidence to the emerging concept that the production of autophagy-related protein isoforms can differentially affect core autophagy machinery bringing an additional level of complexity to the regulation of this biological process in more complex organisms.

Post-transcriptional regulation of ATG1 is a critical node that modulates autophagy during distinct nutrient stresses.

Macroautophagy/autophagy is a highly conserved nutrient-recycling pathway that eukaryotes utilize to combat diverse stresses including nutrient depletion. Dysregulation of autophagy disrupts cellular homeostasis leading to starvation susceptibility in yeast and disease development in humans. In yeast, the robust autophagy response to starvation is controlled by the upregulation of ATG genes, via regulatory processes involving multiple levels of gene expression. Despite the identification of several regulators through genetic studies, the predominant mechanism of regulation modulating the autophagy response to subtle differences in nutrient status remains undefined. Here, we report the unexpected finding that subtle changes in nutrient availability can cause large differences in autophagy flux, governed by hitherto unknown post-transcriptional regulatory mechanisms affecting the expression of the key autophagyinducing kinase Atg1 (ULK1/ULK2 in mammals). We have identified two novel post-transcriptional regulators of ATG1 expression, the kinase Rad53 and the RNA-binding protein Ded1 (DDX3 in mammals). Furthermore, we show that DDX3 regulates ULK1 expression post-transcriptionally, establishing mechanistic conservation and highlighting the power of yeast biology in uncovering regulatory mechanisms that can inform therapeutic approaches.

Highlights in the fight against COVID-19: does autophagy play a role in SARS-CoV-2 infection?

In the preceding months, the novel SARS-CoV-2 pandemic has devastated global communities. The need for safe and effective prophylactic and therapeutic treatments to combat COVID-19 - the human disease resulting from SARS-CoV-2 infection - is clear. Here, we present recent developments in the effort to combat COVID-19 and consider whether SARS-CoV-2 may potentially interact with the host autophagy pathway. Abbreviations: ACE2, angiotensin converting enzyme II; ßCoV, betacoronavirus; COVID-19, Coronavirus Disease 2019; CQ, chloroquine; DMV, double-membrane vesicle; GI, gastrointestinal; HCQ, hydroxychloroquine; IL, interleukin; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MEFs, mouse embryonic fibroblasts; MERS-CoV, Middle East respiratory syndrome coronavirus; MHV, murine hepatitis virus; PE, phosphatidylethanolamine; SARS-CoV, severe acute respiratory syndrome coronavirus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TMPRSS2, transmembrane serine protease 2; TNF, tumor necrosis factor; WHO, World Health Organization.

The LC3-conjugation machinery specifies cargo loading and secretion of extracellular vesicles.

Classical macroautophagy/autophagy functions to maintain cell health during stressful conditions by targeting cytosolic components for degradation and recycling through the lysosomal pathway. In contrast, nondegradative secretory autophagy functions as an alternative autophagy mechanism to mediate extracellular secretion. A recent study published in Nature Cell Biology from the laboratory of Jayanta Debnath has identified components of the LC3-conjugation machinery as mediators in the selection of cargo for nonclassical secretion. Termed LC3-dependent extracellular vesicle loading and secretion (LDELS), this mechanism provides an additional link between secretory autophagy and the release of extracellular vesicles. ABBREVIATIONS: ATG, autophagy-related; BioID, proximity-dependent biotinylation; CM, conditioned medium; EV, extracellular vesicle; HNRNPK, heterogeneous nuclear ribonuclear protein K; ILVs, intralumenal vesicles; LDELS, LC3-dependent EV loading and secretion; LIR, LC3-interacting region; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MS, mass spectrometry; MVBs, multivesicular bodies; ncRNA, non-coding RNA; NSMAF/FAN, neutral sphingomyelinase activation associated factor; P-bodies, processing bodies; PE, phosphatidylethanolamine; RB1CC1/FIP200, RB1 inducible coiled-coil 1; RBP, RNA-binding protein; RNA-seq, RNA sequencing; SAFB, scaffold-attachment factor B; SILAC, stable isotope labeling of amino acids in cell culture; SMPD3/nSMase2, sphingomyelin phosphodiesterase 3; TEM, transmission electron microscopy; TMT, tandem mass tagging.

TEX264 is a major receptor for mammalian reticulophagy.

The endoplasmic reticulum (ER) is the main site of cellular protein and calcium homeostasis, as well as lipid synthesis in eukaryotic cells. Reticulophagy is the selective clearance and degradation of ER components and membranes by the cellular autophagy machinery. Recently, 2 groups (the laboratories of Noboru Mizushima and Wade Harper) independently identified the previously uncharacterized protein TEX264 (testis expressed gene 264) as a major receptor for selective reticulophagy in mammalian cells. Here we highlight and integrate the major findings of their recent work. Abbreviations: AIM: Atg8-interacting motif; AP-MS: affinity purification-mass spectrometry; ATL3: atlastin GTPase 3; Baf A1: bafilomycin A1; CCPG1: cell cycle progression 1; CRISPR: clustered regularly interspaced short palindromic repeats; GABARAP: gamma-aminobutyric acid receptor associated protein; GFP: green fluorescent protein; GyrI: gyrase inhibitor; IDR: intrinsically disordered region; IP: immunoprecipitation; KO: knockout; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; MS: mass spectrometry; MTOR: mechanistic target of rapamycin kinase; RB1CC1/FIP200: RB1-inducible coiled-coil 1; RFP: red fluorescent protein; RNAi: RNA interference; RTN3: reticulon 3; RTN3L: long isoform of RTN3; siRNA: small interfering RNA; SARS: selective autophagy receptors; ss: signal sequence; TEM: transmission electron microscopy, TEX264: testis expressed gene 264; TMT: tandem mass tagging.

Inflammatory-dependent Sting activation induces antiviral autophagy to limit zika virus in the Drosophila brain.

Incidences of congenital syndrome associated with maternal zika virus (ZIKV) infection during pregnancy are well documented; however, the cellular and molecular mechanisms by which ZIKV infection causes these devastating fetal pathologies are still under active investigation. ZIKV is a member of the flavivirus family and is mainly transmitted to human hosts through Aedes mosquito vectors. However, in vivo models for the neurological tropism of the virus and the arthropod vector have been lacking. A recent study published in Cell Host & Microbe from Dr. Sara Cherry's lab investigates both of these key aspects of the ZIKV infectious life cycle. Liu et al. demonstrate how inflammatory activated Sting/dSTING-dependent antiviral macroautophagy/autophagy is sufficient to restrict ZIKV infection in the Drosophila melanogaster brain. Additionally, this study provides further evidence for the ancestral function of autophagy in protecting host cells from viral invaders. Abbreviations: AGO2: Argonaute 2; ATG: autophagy-related; Dcr-2: Dicer-2; DptA/Dipt: Diptericin A; Drs: Drosomycin; DCV: Drosophila C virus; IMD: immune-deficiency; qRT-PCR: quantitative real-time PCR; Rel/NF-κB: Relish; RNAi: RNA interference; ZIKV: zika virus.

On the edge of degradation: Autophagy regulation by RNA decay.

Cells must dynamically adapt to altered environmental conditions, particularly during times of stress, to ensure their ability to function effectively and survive. The macroautophagy/autophagy pathway is highly conserved across eukaryotic cells and promotes cell survival during stressful conditions. In general, basal autophagy occurs at a low level to sustain cellular homeostasis and metabolism. However, autophagy is robustly upregulated in response to nutrient deprivation, pathogen infection and increased accumulation of potentially toxic protein aggregates and superfluous organelles. Within the cell, RNA decay maintains quality control to remove aberrant transcripts and regulate appropriate levels of gene expression. Recent evidence has identified components of the cellular mRNA decay machinery as novel regulators of autophagy. Here, we review current findings that demonstrate how autophagy is modulated through RNA decay. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Turnover and Surveillance > Regulation of RNA Stability.

The exoribonuclease Xrn1 is a post-transcriptional negative regulator of autophagy.

Macroautophagy/autophagy is a conserved catabolic process that promotes survival during stress. Autophagic dysfunction is associated with pathologies such as cancer and neurodegenerative diseases. Thus, autophagy must be strictly modulated at multiple levels (transcriptional, post-transcriptional, translational and post-translational) to prevent deregulation. Relatively little is known about the post-transcriptional control of autophagy. Here we report that the exoribonuclease Xrn1/XRN1 functions as a negative autophagy factor in the yeast Saccharomyces cerevisiae and in mammalian cells. In yeast, chromosomal deletion of XRN1 enhances autophagy and the frequency of autophagosome formation. Loss of Xrn1 results in the upregulation of autophagy-related (ATG) transcripts under nutrient-replete conditions, and this effect is dependent on the ribonuclease activity of Xrn1. Xrn1 expression is regulated by the yeast transcription factor Ash1 in rich conditions. In mammalian cells, siRNA depletion of XRN1 enhances autophagy and the replication of 2 picornaviruses. This work provides insight into the role of the RNA decay factor Xrn1/XRN1 as a post-transcriptional regulator of autophagy.

Transcriptional and post-transcriptional regulation of autophagy in the yeast Saccharomyces cerevisiae.

Autophagy is a highly conserved catabolic pathway that is vital for development, cell survival, and the degradation of dysfunctional organelles and potentially toxic aggregates. Dysregulation of autophagy is associated with cancer, neurodegeneration, and lysosomal storage diseases. Accordingly, autophagy is precisely regulated at multiple levels (transcriptional, post-transcriptional, translational, and post-translational) to prevent aberrant activity. Various model organisms are used to study autophagy, but the baker's yeast Saccharomyces cerevisiae continues to be advantageous for genetic and biochemical analysis of non-selective and selective autophagy. In this Minireview, we focus on the cellular mechanisms that regulate autophagy transcriptionally and post-transcriptionally in S. cerevisiae.

Secretory autophagy holds the key to lysozyme secretion during bacterial infection of the intestine.

In 2013, Dr. Lora Hooper and colleagues described the induction of antibacterial macroautophagy/autophagy in intestinal epithelial cells as a cytoprotective host defense mechanism against invading Salmonella enterica serovar Typhimurium (S. Typhimurium). Canonical autophagy functions in a primarily degradative capacity to safeguard cells and ensure survival during stress conditions, including pathogen infection. In contrast, secretory autophagy has emerged as an alternative nondegradative mechanism for cellular trafficking and unconventional protein secretion. More recently, a study by Bel et al. from Dr. Hooper's lab describes how intestinal Paneth cells exploit the endoplasmic reticulum (ER) stress response to release antibacterial lysozyme through secretory autophagy in response to S. Typhimurium infection.

A three-dimensional culture system recapitulates placental syncytiotrophoblast development and microbial resistance.

In eutherians, the placenta acts as a barrier and conduit at the maternal-fetal interface. Syncytiotrophoblasts, the multinucleated cells that cover the placental villous tree surfaces of the human placenta, are directly bathed in maternal blood and are formed by the fusion of progenitor cytotrophoblasts that underlie them. Despite their crucial role in fetal protection, many of the events that govern trophoblast fusion and protection from microbial infection are unknown. We describe a three-dimensional (3D)-based culture model using human JEG-3 trophoblast cells that develop syncytiotrophoblast phenotypes when cocultured with human microvascular endothelial cells. JEG-3 cells cultured in this system exhibit enhanced fusogenic activity and morphological and secretory activities strikingly similar to those of primary human syncytiotrophoblasts. RNASeq analyses extend the observed functional similarities to the transcriptome, where we observed significant overlap between syncytiotrophoblast-specific genes and 3D JEG-3 cultures. Furthermore, JEG-3 cells cultured in 3D are resistant to infection by viruses and Toxoplasma gondii, which mimics the high resistance of syncytiotrophoblasts to microbial infections in vivo. Given that this system is genetically manipulatable, it provides a new platform to dissect the mechanisms involved in syncytiotrophoblast development and microbial resistance.

Atg41/Icy2 regulates autophagosome formation.

Macroautophagy (hereafter autophagy) is one of the major degradation systems in eukaryotic cells, and its dysfunction may result in diseases ranging from neurodegeneration to cancer. Although most of the autophagy-related (Atg) proteins that function in this pathway were first identified in yeast, many were subsequently shown to have homologs in higher eukaryotes including humans, and the overall mechanism of autophagy is highly conserved. The most prominent feature of autophagy is the formation of a double-membrane sequestering compartment, the phagophore; this transient organelle surrounds part of the cytoplasm and matures into an autophagosome, which subsequently fuses with the vacuole or lysosome to allow degradation of the cargo. Much attention has focused on the process involved in phagophore nucleation and expansion, but many questions remain. Here, we identified the yeast protein Icy2, which we now name Atg41, as playing a role in autophagosome formation. Atg41 interacts with the transmembrane protein Atg9, a key component involved in autophagosome biogenesis, and both proteins display a similar localization profile. Under autophagy-inducing conditions the expression level of Atg41 increases dramatically and is regulated by the transcription factor Gcn4. This work provides further insight into the mechanism of Atg9 function and the dynamics of sequestering membrane formation during autophagy.

A missing piece of the puzzle: Atg11 functions as a scaffold to activate Atg1 for selective autophagy.

The mechanism regulating Atg1 kinase activity for the initiation of selective macroautophagy (hereafter autophagy) under nutrient-rich conditions has been a long-standing question. Canonically in yeast, nutrient starvation or rapamycin treatment repress TOR complex 1 and stimulate the Atg1 complex (including at least Atg1, Atg13, Atg17, Atg29 and Atg31), which allows the recruitment of downstream autophagy-related (Atg) components to the phagophore assembly site (PAS), culminating in phagophore formation, and, subsequently, autophagosome biogenesis. Atg1 also functions under conditions promoting selective autophagy that do not necessarily require nutrient deprivation for induction. However, there has been some debate as to whether Atg1 catalytic activity plays a more important role under conditions of nutrient starvation-induced autophagy (i.e., bulk autophagy) vs. selective autophagy (e.g., the cytoplasm-to-vacuole targeting [Cvt] pathway). A recent paper by Kamber and colleagues investigates the mechanism regulating Atg1 activity during selective autophagy.

Rph1/KDM4 mediates nutrient-limitation signaling that leads to the transcriptional induction of autophagy.

BACKGROUND: Autophagy is a conserved process mediating vacuolar degradation and recycling. Autophagy is highly upregulated upon various stresses and is essential for cell survival in deleterious conditions. Autophagy defects are associated with severe pathologies, whereas unchecked autophagy activity causes cell death. Therefore, to support proper cellular homeostasis, the induction and amplitude of autophagy activity have to be finely regulated. Transcriptional control is a critical, yet largely unexplored, aspect of autophagy regulation. In particular, little is known about the signaling pathways modulating the expression of autophagy-related genes, and only a few transcriptional regulators have been identified as contributing in the control of this process. RESULTS: We identified Rph1 as a negative regulator of the transcription of several ATG genes and a repressor of autophagy induction. Rph1 is a histone demethylase protein, but it regulates autophagy independently of its demethylase activity. Rim15 mediates the phosphorylation of Rph1 upon nitrogen starvation, which causes an inhibition of its function. Preventing Rph1 phosphorylation or overexpressing the protein causes a severe block in autophagy induction. A similar function of Rph1/KDM4 is seen in mammalian cells, indicating that this process is highly conserved. CONCLUSION: Rph1 maintains autophagy at a low level in nutrient-rich conditions; upon nutrient limitation, the inhibition of its activity is a prerequisite to the induction of ATG gene transcription and autophagy.

Human trophoblasts confer resistance to viruses implicated in perinatal infection.

OBJECTIVE: Primary human trophoblasts were previously shown to be resistant to viral infection, and able to confer this resistance to nontrophoblast cells. Can trophoblasts protect nontrophoblastic cells from infection by viruses or other intracellular pathogens that are implicated in perinatal infection? STUDY DESIGN: Isolated primary term human trophoblasts were cultured for 48-72 hours. Diverse nonplacental human cell lines (U2OS, human foreskin fibroblast, TZM-bl, MeWo, and Caco-2) were preexposed to either trophoblast conditioned medium, nonconditioned medium, or miR-517-3p for 24 hours. Cells were infected with several viral and nonviral pathogens known to be associated with perinatal infections. Cellular infection was defined and quantified by plaque assays, luciferase assays, microscopy, and/or colonization assays. Differences in infection were assessed by Student t test or analysis of variance with Bonferroni correction. RESULTS: Infection by rubella and other togaviruses, human immunodeficiency virus-1, and varicella zoster was attenuated in cells preexposed to trophoblast-conditioned medium (P < .05), and a partial effect by the chromosome 19 microRNA miR-517-3p on specific pathogens. The conditioned medium had no effect on infection by Toxoplasma gondii or Listeria monocytogenes. CONCLUSION: Our findings indicate that medium conditioned by primary human trophoblasts attenuates viral infection in nontrophoblastic cells. Our data point to a trophoblast-specific antiviral effect that may be exploited therapeutically.

The yeast Saccharomyces cerevisiae: an overview of methods to study autophagy progression.

Macroautophagy (hereafter autophagy) is a highly evolutionarily conserved process essential for sustaining cellular integrity, homeostasis, and survival. Most eukaryotic cells constitutively undergo autophagy at a low basal level. However, various stimuli, including starvation, organelle deterioration, stress, and pathogen infection, potently upregulate autophagy. The hallmark morphological feature of autophagy is the formation of the double-membrane vesicle known as the autophagosome. In yeast, flux through the pathway culminates in autophagosome-vacuole fusion, and the subsequent degradation of the resulting autophagic bodies and cargo by vacuolar hydrolases, followed by efflux of the breakdown products. Importantly, aberrant autophagy is associated with diverse human pathologies. Thus, there is a need for ongoing work in this area to further understand the cellular factors regulating this process. The field of autophagy research has grown exponentially in recent years, and although numerous model organisms are being used to investigate autophagy, the baker's yeast Saccharomyces cerevisiae remains highly relevant, as there are significant and unique benefits to working with this organism. In this review, we will focus on the current methods available to evaluate and monitor autophagy in S. cerevisiae, which in several cases have also been subsequently exploited in higher eukaryotes.

Assays for the biochemical and ultrastructural measurement of selective and nonselective types of autophagy in the yeast Saccharomyces cerevisiae.

Autophagy is a conserved intracellular catabolic pathway that degrades unnecessary or dysfunctional cellular components. Components destined for degradation are sequestered into double-membrane vesicles called autophagosomes, which subsequently fuse with the vacuole/lysosome delivering their cargo into the interior of this organelle for turnover. Autophagosomes are generated through the concerted action of the autophagy-related (Atg) proteins. The yeast Saccharomyces cerevisiae has been key in the identification of the corresponding genes and their characterization, and it remains one of the leading model systems for the investigation of the molecular mechanism and functions of autophagy. In particular, it is still pivotal for the study of selective types of autophagy. The objective of this review is to present detailed protocols of the methods available to monitor the progression of both nonselective and selective types of autophagy, and to discuss their advantages and disadvantages. The ultimate aim is to provide researchers with the information necessary to select the optimal approach to address their biological question.

BPIFB3 regulates autophagy and coxsackievirus B replication through a noncanonical pathway independent of the core initiation machinery.

UNLABELLED: Enteroviruses require autophagy to facilitate the formation of autophagosome (AP)-like double-membrane vesicles that provide the scaffolding for RNA replication. Here, we identify bactericidal/permeability-increasing protein (BPI) fold-containing family B, member 3 (BPIFB3) as a gene whose silencing greatly enhances coxsackievirus B (CVB) replication and induces dramatic alterations in the morphology of CVB-induced replication organelles. We show that BPIFB3 is associated with the endoplasmic reticulum (ER), and its silencing by RNA interference enhances basal levels of autophagy and promotes increased autophagy during CVB replication. Conversely, overexpression of BPIFB3 inhibits CVB replication, dramatically alters the morphology of LC3B-positive vesicles, and suppresses autophagy in response to rapamycin. In addition, we found that, whereas silencing of core autophagy components associated with the initiation of APs in control cells suppressed CVB replication, silencing of these same components had no effect on CVB-induced autophagy or viral replication in cells transfected with BPIFB3 small interfering RNA. Based on these results, taken together, this study reports on a previously uncharacterized regulator of enterovirus infection that controls replication through a noncanonical pathway independent from the core autophagy initiation machinery. IMPORTANCE: Coxsackievirus B (CVB) infections are commonly associated with dilated cardiomyopathy, a condition that accounts for nearly half of all heart transplants annually. During infection, CVB co-opts a cellular pathway, termed autophagy, to provide the membranes necessary for its replication. Autophagy is an evolutionarily conserved process by which cells ingest damaged organelles as a means of maintaining cell homeostasis. Here, we report on a novel regulator of autophagy, bactericidal/permeability-increasing protein (BPI) fold-containing family B, member 3 (BPIFB3), whose expression functions to restrict CVB replication by suppressing key steps in the authophagic process. We show that loss of BPIFB3 expression greatly enhances CVB replication while having no effect on replication of poliovirus, a closely related virus. Our results thus identify a novel host cell therapeutic target whose function could be targeted to alter CVB replication.