SEARCH · PubMed Health

Results for “endosome”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed2025

In Vivo CRISPR Activation Screening Reveals Chromosome 1q Genes VPS72, GBA1, and MRPL9 Drive Hepatocellular Carcinoma.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) frequently undergoes regional chromosomal amplification, resulting in elevated gene expression levels. We aimed to elucidate the role of these poorly understood genetic changes by using CRISPR activation (CRISPRa) screening in mouse livers to identify which genes within these amplified loci are cancer driver genes. METHODS: We used data from The Cancer Genome Atlas to identify that frequently copy number-amplified and up-regulated genes all reside on human chromosomes 1q and 8q. We generated CRISPRa screening transposons that contain oncogenic Myc to drive tumor formation. We conducted CRISPRa screens in vivo in the liver to identify tumor driver genes. We extensively validated the findings in separate mice and performed RNA sequencing analysis to explore mechanisms driving tumorigenesis. RESULTS: We targeted genes that frequently undergo amplification in human HCC using an in vivo CRISPRa screening system in mice, which induced extensive liver tumorigenesis. Human chromosome 1q genes Zbtb7b, Vps72, Gba1, and Mrpl9 emerged as drivers of liver tumorigenesis. In human HCC there is a trend in correlation between levels of MRPL9, VPS72, or GBA1 and poor survival. In validation assays, activation of Vps72, Gba1, or Mrpl9 resulted in extensive liver tumorigenesis and decreased survival in mice. RNA sequencing revealed different mechanisms driving HCC, with Mrpl9 activation altering genes functionally related to mitochondrial function, Vps72 levels altering phospholipid metabolism, and Gba1 activation enhancing endosomal-lysosomal activity, all leading to promotion of cellular proliferation. Analysis of human tumor tissues with high levels of MRPL9, VPS72, or GBA1 revealed congruent results, indicating conserved mechanisms driving HCC. CONCLUSIONS: This study reveals chromosome 1q genes Vps72, Gba1, and Mrpl9 as drivers of HCC. Future efforts to prevent or treat HCC can focus on these new driver genes.

Animals↗

PubMed2024

Proteomic Characterization of Ubiquitin Carboxyl-Terminal Hydrolase 19 Deficient Cells Reveals a Role for USP19 in the Secretion of Lysosomal Proteins.

Ubiquitin carboxyl-terminal hydrolase 19 (USP19) is a unique deubiquitinase, characterized by multiple variants generated by alternative splicing. Several variants bear a C-terminal transmembrane domain that anchors them to the endoplasmic reticulum. Other than regulating protein stability by preventing proteasome degradation, USP19 has been reported to rescue substrates from endoplasmic reticulum-associated protein degradation in a catalytic-independent manner, promote autophagy, and address proteins to lysosomal degradation via endosomal microautophagy. USP19 has recently emerged as the protein responsible for the unconventional secretion of misfolded proteins including Parkinson's disease-associated protein α-synuclein. Despite mounting evidence that USP19 plays crucial roles in several biological processes, the underlying mechanisms are unclear due to lack of information on the physiological substrates of USP19. Herein, we used high-resolution quantitative proteomics to analyze changes in the secretome and cell proteome induced by the loss of USP19 to identify proteins whose secretion or turnover is regulated by USP19. We found that ablation of USP19 induced significant proteomic alterations both in and out of the cell. Loss of USP19 impaired the release of several lysosomal proteins, including legumain (LGMN) and several cathepsins. In order to understand the underlaying mechanism, we dissected the USP19-regulated secretion of LGMN in several cell types. We found that LGMN was not a deubiquitinase substrate of USP19 and that its USP19-dependent release did not require their direct interaction. LGMN secretion occurred by a mechanism that involved the Golgi apparatus, autophagosome formation, and lysosome function. This mechanism resembled the recently described "lysosomal exocytosis," by which lysosomal hydrolases are secreted, when ubiquitination of p62 is increased in cells lacking deubiquitinases such as USP15 and USP17. In conclusion, our proteomic characterization of USP19 has identified a collection of proteins in the secretome and within the cell that are regulated by USP19, which link USP19 to the secretion of lysosomal proteins, including LGMN.

Humans↗

PubMed2026

Kv11.1 (hERG) Protein Interaction Networks Connect Endocytic Trafficking to Polygenic Influences on Cardiac Repolarization.

Polygenic scores (PGS) capture the combined effect of many common genetic variants on quantitative traits and disease risk, yet their functional consequences at the protein level remain poorly defined. Here, we integrated quantitative and interaction proteomics to resolve how polygenic liability for cardiac repolarization manifests in human cells. We studied human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from donors with extreme PGS for QT interval duration, a clinically relevant electrophysiologic trait associated with arrhythmia risk. Global quantitative proteomics revealed increased abundance of mitochondrial proteins in high-PGS cardiomyocytes. To define protein network-level effects on a key repolarizing ion channel, we performed multiplexed affinity purification-mass spectrometry (AP-MS) of Kv11.1. While mitochondrial changes did not directly explain Kv11.1-associated complexes, interactome analysis revealed increased association of Kv11.1 with myosin motor proteins and endosomal recycling machinery in high-PGS cells. These findings suggest altered channel trafficking dynamics of Kv11.1, distinct from the trafficking defects observed in monogenic Kv11.1 variants. Together, these data show that integrating global and interaction proteomics can resolve how polygenic variation reshapes protein networks. Future work using these methods could connect genomic risk to subcellular remodeling and our work provides a generalizable framework to probe the proteomic basis of complex traits. SIGNIFICANCE STATEMENT: Polygenic scores (PGS) predict disease risk, but how biological pathways are influenced by these common variants remains difficult to define. We generated human induced pluripotent stem cells from individuals with extreme high- and low- PGS for QT interval, a key electrocardiographic measure linked to arrhythmia risk. By combining global proteomics and interactomics for a common ion channel involved in regulating the QT interval (Kv11.1) we found potential mechanisms that are influenced by common genetic traits in patients. Our work provides an approach to connect polygenic scores to pathway-level molecular mechanisms in human cells and a general framework for uncovering how complex genetic architecture drives disease-relevant biology.

AP-MS↗

PubMed2026

Engineering CRISPR nanoplatforms to deplete cancer stem cells: Delivery checkpoints, target plasticity, and clinical viability.

Cancer stem cells (CSCs) sustain tumor initiation, therapy resistance, and relapse, yet evade durable control because they switch phenotype, enter quiescence, shelter within protective niches, resist drug efflux, and share markers with normal stem cells. Programmable CRISPR editing can disable intracellular self-renewal dependencies that antibodies and small molecules cannot reach, whereas only nanoscale carriers can confine such editing to intended cells; neither component alone solves the CSC problem. This review reframes CSC-directed CRISPR nanomedicine as an integrated design problem. We examine why target plasticity defeats static single-marker targeting; the sequential delivery checkpoints spanning blood stability, organ selection, tumor penetration, CSC recognition, endosomal escape, and productive editing; and advanced architectures including organ-selective lipid nanoparticles, biomimetic and vesicle carriers, metal-organic frameworks, and logic-gated systems. Genotoxicity, immunogenicity, incomplete depletion, manufacturing reproducibility, and absent CSC-specific clinical evidence remain limiting. Clinical viability, not imminent cure, is the realistic near-term objective.

Neoplastic Stem Cells↗

PubMed2026

Engineering extracellular vesicles for targeted siRNA delivery: Advances, therapeutic applications, and clinical translation.

Small interfering RNA (siRNA) therapeutics have emerged as a transformative approach for sequence-specific gene silencing, offering the potential to treat a broad spectrum of diseases by selectively suppressing disease-associated genes. However, the clinical translation of siRNA remains limited by rapid enzymatic degradation, poor cellular uptake, inadequate endosomal escape, and off-target effects, necessitating the development of efficient delivery systems. Extracellular vesicles (EVs) have gained considerable attention as natural nanocarriers owing to their excellent biocompatibility, low immunogenicity, intrinsic targeting capability, and ability to protect therapeutic cargo while traversing complex biological barriers. This review comprehensively discusses the biological characteristics of EVs, the molecular basis of RNA interference, and the major challenges associated with siRNA delivery [Fig. 1]. Recent advances in EV engineering, including cargo-loading strategies such as electroporation, sonication, extrusion, parent-cell engineering, and microfluidic approaches, together with surface functionalization using peptides, antibodies, aptamers, and hybrid nanoplatforms, are critically evaluated for improving targeting specificity and intracellular delivery. Furthermore, the therapeutic applications of engineered EV-mediated siRNA delivery in cancer, neurological disorders, liver diseases, cardiovascular diseases, inflammatory disorders, and infectious diseases are systematically summarized, highlighting their potential to enhance gene silencing while minimizing systemic toxicity. Current challenges related to large-scale manufacturing, cargo-loading efficiency, standardization, quality control, regulatory approval, and clinical translation are also discussed, together with emerging technologies involving synthetic biology, genome engineering, artificial intelligence, and multifunctional hybrid vesicles. Overall, engineered extracellular vesicles represent a highly versatile and biologically inspired platform for targeted siRNA delivery, providing a promising foundation for the development of next-generation precision RNA therapeutics and accelerating the clinical translation of gene-silencing strategies.

Extracellular vesicle engineering↗

PubMed1979

Endocytosis and breakdown of 125I-labelled lactate dehydrogenase isoenzyme M4 by rat liver and spleen in vivo.

1. Porcine lactate dehydrogenase isoenzyme M4 was labelled with 125I and injected intravenously into rats. Enzyme activity and radioactivity in plasma were cleared in an identical way with a half-life of about 30 min. This half-life was the same as that of unlabelled enzyme. 2. Uptake of label by liver and spleen was determined. Radioactivity in these tissues increased up to about 13 min after injection and subsequently declined. Radioautography indicated uptake of the enzyme by sinusoidal liver cells (probably Kupffer cells) and by spleen macrophages. After differential fractionation of liver, acid-precipitable radioactivity was largely found in the light mitochondrial and microsomal fractions, suggesting localization in lysosomes and endosomes respectively. 3. The amount of acid-soluble radioactive breakdown products in plasma started to rise between 7 and 15 min after injection. Breakdown in liver and spleen was retarded by previous injection of suramin, an inhibitor of lysosomal proteolysis. 4. The contribution of liver and spleen towards the clearance of the enzyme could be calculated from its half-life in plasma and its uptake by the organs within the first 13 min period after injection. Our results indicate that about 65% and 12% of the injected dose was taken up, and subsequently broken down, by liver and spleen respectively. 5. Unlabelled porcine lactate dehydrogenase isoenzyme H4 showed a plasma half-life of about 8 h. This isoenzyme is therefore endocytosed by liver at a much slower rate than isoenzyme M4 (if it is taken up at all).

Animals↗

PubMed2024

TMPRSS2-mediated SARS-CoV-2 uptake boosts innate immune activation, enhances cytopathology, and drives convergent virus evolution.

The accessory protease transmembrane protease serine 2 (TMPRSS2) enhances severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uptake into ACE2-expressing cells, although how increased entry impacts downstream viral and host processes remains unclear. To investigate this in more detail, we performed infection assays in engineered cells promoting ACE2-mediated entry with and without TMPRSS2 coexpression. Electron microscopy and inhibitor experiments indicated TMPRSS2-mediated cell entry was associated with increased virion internalization into endosomes, and partially dependent upon clathrin-mediated endocytosis. TMPRSS2 increased panvariant uptake efficiency and enhanced early rates of virus replication, transcription, and secretion, with variant-specific profiles observed. On the host side, transcriptional profiling confirmed the magnitude of infection-induced antiviral and proinflammatory responses were linked to uptake efficiency, with TMPRSS2-assisted entry boosting early antiviral responses. In addition, TMPRSS2-enhanced infections increased rates of cytopathology, apoptosis, and necrosis and modulated virus secretion kinetics in a variant-specific manner. On the virus side, convergent signatures of cell-uptake-dependent innate immune induction were recorded in viral genomes, manifesting as switches in dominant coupled Nsp3 residues whose frequencies were correlated to the magnitude of the cellular response to infection. Experimentally, we demonstrated that selected Nsp3 mutations conferred enhanced interferon antagonism. More broadly, we show that TMPRSS2 orthologues from evolutionarily diverse mammals facilitate panvariant enhancement of cell uptake. In summary, our study uncovers previously unreported associations, linking cell entry efficiency to innate immune activation kinetics, cell death rates, virus secretion dynamics, and convergent selection of viral mutations. These data expand our understanding of TMPRSS2's role in the SARS-CoV-2 life cycle and confirm its broader significance in zoonotic reservoirs and animal models.

SARS-CoV-2↗

PubMed2026

The archaeal roots of eukaryotic life.

Resolving the biological and geological events that led to the origin of eukaryotes is an ongoing challenge in biology. A major step in the evolution of complex cellular life was the merger between an ancestral host cell and a bacterium (that became the mitochondrion) some two billion years ago. Recently, metagenomics has enabled the reconstruction of a broad diversity of genomes, referred to as the Asgard Archaea. The Asgards are monophyletic with eukaryotes on the tree of life. Asgards have an array of genes, previously thought exclusive to eukaryotes, involved in cellular trafficking, the ubiquitin system, endosomal sorting, and cytoskeleton formation, with growing evidence demonstrating the functions of these proteins mirror those in eukaryotes. This gene repertoire suggests that these Archaea are descendants of the archaeal host from which eukaryotes evolved. Increased sampling has revealed that Asgard lineages are metabolically versatile and play key roles in various ecosystems and uncovered evolutionary transitions between Archaea and eukaryotes, such as innovations in eukaryotic defense systems. The positioning of eukaryotes in the Asgards is debated, but eukaryotes appear to branch within the Heimdallarchaeia. Lineages within this group, particularly Hodarchaeales and Kariarchaeaceae, contain a broad repertoire of eukaryote-like traits, including high-energy yielding metabolisms. Observing and studying Asgard interactions with bacterial descendants of mitochondria in a modern setting will transform our understanding of the origin of complex cellular life.

Archaea↗

PubMed2025

The pathway of autophagy in the epigenetic landscape of Mycobacterium-host interactions.

Macroautophagy (autophagy) is an evolutionarily conserved process that degrades excess cytoplasmic components, such as protein aggregates and damaged organelles, by encapsulating them within double-membrane autophagosomes. These autophagosomes undergo distinct stages - initiation, phagophore nucleation, expansion, and closure - before fusing with lysosomes (or occasionally endosomes) for degradation and recycling. This process is regulated by ATG (autophagy related) proteins, which govern autophagosome formation and lysosomal fusion. Epigenetic modifications and transcription factors can regulate ATG gene expression in the nucleus. Autophagy also plays a key role in eliminating intracellular Mycobacterium tuberculosis (Mtb) through the lytic and antimicrobial activities of autolysosomes, which are more potent antimicrobial compartments than conventional phagosomes. Emerging evidence suggests that Mtb can modify the host epigenome and transcriptional machinery, significantly affecting the host immune response. This review explores the epigenetic regulation of autophagy during mycobacterium-host interactions. The interplay between epigenetic regulation and autophagy highlights a crucial aspect of host-pathogen interactions during Mtb infection. Understanding how Mtb manipulates the host epigenome to regulate autophagy could lead to the development of novel therapeutic strategies that enhance autophagic pathways or counteract Mtb's immune evasion tactics.Abbreviations: AM: Alveolar macrophages; ATG: autophagy related; DNMT: DNA methyltransferase; FOXO3: forkhead box O3; HAT: histone acetyltransferase; HDAC: histone deacetylase; MIR: microRNA; MTOR: mechanistic target of rapamycin kinase; Mtb: Mycobacterium tuberculosis; ROS: reactive oxygen species; SIRT: sirtuin; STPK: serine/threonine protein kinase.

Autophagy↗

PubMed2026

Protein sorting and proteostasis mechanisms in CFTR-related exocrine pancreas dysfunction: A systematic narrative review.

The pancreas consists of exocrine and endocrine compartments. In the exocrine pancreas, cystic fibrosis transmembrane conductance regulator (CFTR) functions mainly in ductal epithelial cells as a chloride and bicarbonate channel. Its activity depends on proper protein folding, trafficking, and localization to the apical membrane. This systematic narrative review aims to synthesize the available evidence on the role of protein sorting machinery in CFTR channelopathies and its contribution to exocrine pancreatic dysfunction. A thorough search was conducted using PRISMA criteria on PubMed, Wiley Online Library, and Scopus for studies published in English between January 2000 and November 2025. Twenty studies that met the inclusion criteria were included in this review. Pathogenic CFTR variants impair protein folding, endoplasmic reticulum (ER) exit, and endosomal recycling, resulting in reduced apical membrane expression and stability. These defects disrupt the localization of associated transporters and secretory proteins, impair ductal bicarbonate secretion, alter zymogen handling, and promote acinar injury, although these claims are supported mainly by indirect experimental models and therefore require clinical confirmation. CFTR channelopathies in the exocrine pancreas encompass both ion transport defects and broader disruptions of protein sorting machinery. CFTR may contribute to the assembly, stabilization, or localization of selected apical transport complexes, and its loss can secondarily alter epithelial organization. Therapeutic approaches targeting both channel correction and intracellular trafficking may improve pancreatic function and mitigate disease progression.

Humans↗

PubMed1975

Colchicine effects on lysosomal enzyme induction and intracellular degradation in the cultivated macrophage.

The effects of colchicine on lysosomal fusion and lysosomal enzyme induction in the cultivated mouse peritoneal macrophage have been examined. Colchicine (10- minus 6 M), but not lumicolchicine, inhibited lysosomal enzyme induction by both phagocytic and pinocytic stimuli. In addition, the drug significantly retarded pinocytic uptake of [3-H] sucrose and transport of the amino acids [3-H] alpha aminoisobutyric acid and L-[3-H] leucine. In contrast, lumicolchicine had no effect on pinocytosis or amino acid transport. Thus, a role for intact microtubules in lysosomal enzyme induction, pinocytosis, and amino acid uptake in these cells is suggested. That colchicine inhibited lysosomal enzyme induction by phagocytic stimuli under conditions in which pinocytosis contributed little to the enzyme rise indicated that inhibition of pinocytosis was unlikely to account for colchicine effects on lysosomal enzyme induction. Effects of colchicine on degradation of phagocytized and pinocytized substrates were examined to determine if intact microtubules are required for fusion among lysosomes, pinosomes, and phagosomes. Colchicine did not alter the rate of intracellular digestion of radiolabeled bacteria by the cultivated macrophage. Similarly, it had no effect on enzymatic hydrolysis of intracellular [3-H] sucrose resulting from uptake of exogenous invertase. The finding that colchicine had no effect on the functional consequences of fusion of lysosomes with endosomes suggests that intact microtubules are not required for fusion among these constituents of the vacuolar apparatus.

Acid Phosphatase↗

PubMed2026

The present and future of nonviral delivery-based genome editing for hereditary hearing loss.

PURPOSE OF REVIEW: This review summarizes nonviral genome-editing delivery platforms for hereditary hearing loss, focusing on lipid nanoparticles (LNPs) and engineered virus-like particles (eVLPs), and discusses their advantages over adeno-associated virus-based delivery, as well as the barriers to clinical translation. RECENT FINDINGS: Recent advances have established LNPs as a clinically advanced nonviral platform, although challenges related to inner ear biodistribution, cell type specificity, endosomal escape, and immunogenicity remain to be addressed. In parallel, eVLPs have undergone substantial technical evolution, progressing from early low efficiency systems to advanced base editor- and prime editor-eVLP architectures that enhance cargo loading and editing efficiency. Extracellular vesicle-based genome editing has also emerged as an additional platform, although issues related to reproducibility, loading efficiency, and scalability remain major hurdles. SUMMARY: Nonviral genome editing platforms expand the therapeutic toolkit for hereditary hearing loss by enabling transient delivery of genome editors with potential safety advantages. Future efforts should focus on characterizing biodistribution and immunogenicity, refining cell type-specific tropism, and establishing scalable manufacturing processes to enable successful clinical translation.

Humans↗

PubMed2026

The N6-methyladenosine reader IGF2BP2 in T-cell lymphoma.

Peripheral T-cell lymphoma (PTCL) represents a highly heterogeneous and aggressive lymphoid neoplasm that lacks pathogenic biomarkers of RNA modification with therapeutic potential. IGF2BP2 is recognized as an N6-methyladenosine reader critically involved in oncogenesis. In this study, we observed consistently high expression of IGF2BP2 across common nodal PTCL subtypes in 3 independent external cohorts, which was further confirmed in our RNA-sequencing (RNA-seq) data set of 196 patients with newly diagnosed PTCL. Both in vitro and in vivo, IGF2BP2 promoted tumor cell growth and inhibited CD8+ T-cell infiltration within the tumor microenvironment. Mechanistically, IGF2BP2 bound to endosome-related genes (RAB4, VPS35, RAB9, and STAM) to maintain their stability, which resulted in enhanced endocytic activity and increased internalization of membrane proteins, and ultimately induced tumor cell proliferation and inhibition of CD8+ T-cell-mediated tumor cytotoxicity. The relationship between IGF2BP2 and endocytosis-associated genes was confirmed using RNA-seq data from patients with PTCL. IGF2BP2 as an upstream regulator of both tumor growth and immune suppression was further demonstrated in patient-derived xenograft models and a coculture system established using tumor samples from patients with PTCL and peripheral blood mononuclear cells. Notably, therapeutic targeting of IGF2BP2 with CWI1-2 suppressed endocytosis and impeded tumor growth in both cell lines and patient-derived xenograft models. Collectively, our findings highlight IGF2BP2 as a clinically relevant oncogenic driver in PTCL that integrates tumor-intrinsic growth signals with immune evasion through endocytosis-centered regulation, providing a novel therapeutic rationale for RNA modification-based strategies that concurrently target tumor cells and the tumor microenvironment.

Humans↗

PubMed2026

Unlocking the potential of bacteriophage-based therapeutic gene delivery in hepatocellular carcinoma.

Liver cancer, mainly hepatocellular carcinoma (HCC), remains a global health burden marked by poor prognosis with limited therapeutic efficacy, and high recurrence rates. HCC remains one of the most lethal malignancies worldwide, with limited therapeutic options and high resistance to conventional treatments. Despite low therapeutic efficacy, molecular heterogeneity, treatment resistance and high recurrence rate, hepatocellular carcinoma (HCC) is still a significant health problem worldwide. These restrictions have stimulated the research of focused methods for delivering therapeutic genetic payload into cancer cells. Bacteriophages have been gaining growing attention as an emerging delivery platform due to their genetic versatility, ease of engineering, ability to be surface modified and payload targeted. In this narrative review, the therapeutic potential of engineered bacteriophages in the context of HCC therapy is critically analyzed focusing on phage display-mediated tumor targeting, phage-mediated intracellular gene delivery, TRAIL gene delivery, and CRISPR/Cas-based therapeutic strategies. It has been previously noted in the literature that phage display can be used to attach tumor-targeting ligands to the surface of a phage, which may aid in the recognition of receptors at the tumor site and promote targeted delivery to the receptor. Therapeutic application is stunted by inefficient trafficking to the cytosol, endosomal degradation, immune recognition and clearance, vector stability, manufacturing scalability and regulatory issues. In conclusion, engineered bacteriophages are a promising and versatile tool for targeted gene delivery in HCC but more mechanistic, preclinical and translational research is needed to prove their therapeutic effectiveness and clinical usefulness for this purpose.

Humans↗

PubMed1978

The ultrastructure of cell division in Euglena gracilis.

The ultrastructure of mitosis in Euglena gracilis was investigated. At preprophase the nucleus migrates anteriorly and associates with the basal bodies. Flagella and basal bodies replicate at preprophase. Cells retain motility throughout division. The reservoir and the prophase nucleus elongate perpendicular to the incipient cleavage furrow. One basal body pair surrounded by a ribosome-free zone is found at each of the nuclear poles. The spindle forms within the intact nuclear envelope- Polar fenestrae are absent. At metaphase, the endosome is elongated from pole to pole, and chromosomes are loosely arranged in the equatorial region. Distinct, trilayered kinetochores are present. Spindle elongates as chromosomes migrate to the poles forming a dumb-bell shaped nucleus by telophase. Daughter nuclei are formed by constriction of the nuclear envelope. Cytokinesis is accomplished by furrowing. Cell division in Euglena is compared with that of certain other algae.

Animals↗

PubMed2025

Expression of intron-containing HIV-1 RNA induces NLRP1 inflammasome activation in myeloid cells.

Despite the success of antiretroviral therapy in suppressing plasma viremia in people living with human immunodeficiency virus type-1 (HIV-1), persistent viral RNA expression in tissue reservoirs is observed and can contribute to HIV-1-induced immunopathology and comorbidities. Infection of long-lived innate immune cells, such as tissue-resident macrophages and microglia may contribute to persistent viral RNA production and chronic inflammation. We recently reported that de novo cytoplasmic expression of HIV-1 intron-containing RNA (icRNA) in macrophages and microglia leads to MDA5 and MAVS-dependent innate immune sensing and induction of type I IFN responses, demonstrating that HIV icRNA is a pathogen-associated molecular pattern (PAMP). In this report, we show that cytoplasmic expression of HIV-1 icRNA also induces NLRP1 inflammasome activation and IL-1β secretion in macrophages and microglia in an RLR- and endosomal TLR-independent manner. Infection of both macrophages and microglia with either replication-competent or single-cycle HIV-1 induced IL-1β secretion, which was attenuated when cytoplasmic expression of viral icRNA was prevented. While IL-1β secretion was blocked by treatment with caspase-1 inhibitors or knockdown of NLRP1 or caspase-1 expression in HIV-infected macrophages, overexpression of NLRP1 significantly enhanced IL-1β secretion in an HIV-icRNA-dependent manner. Immunoprecipitation analysis revealed interaction of HIV-1 icRNA, but not multiply-spliced HIV-1 RNA, with NLRP1, suggesting that HIV-1 icRNA sensing by NLRP1 is sufficient to trigger inflammasome activation. Together, these findings reveal a pathway of NLRP1 inflammasome activation induced by de novo expressed HIV icRNA in HIV-infected myeloid cells.

HIV-1↗

PubMed2026

Direct interaction between RSV polymerase L and active Rab11a mediates viral ribonucleoprotein transport to assembly sites.

Respiratory syncytial virus (RSV) is an enveloped, negative-sense, single-stranded RNA virus whose ribonucleoproteins (vRNPs) must be transported from cytoplasmic viral factories to the plasma membrane for efficient virion assembly. Viral vRNPs comprise genomic RNA encapsidated by nucleoprotein N and associated with the polymerase complex (L, P, and M2-1). It was previously demonstrated that newly synthesized vRNPs are transported along microtubules by hijacking Rab11a, a small GTPase involved in the regulation of recycling endosomes. In our previous study, we showed an interaction between Rab11a and vRNPs in infected cells by immunoprecipitation assays, nevertheless the molecular mechanisms underlying Rab11a viral hijacking remained unknown. Here, we provide the first comprehensive characterization of the interaction between RSV vRNPs and Rab11a using immunoprecipitation, immunofluorescence colocalization, GST pull-down assays, and biolayer interferometry. We demonstrate that the viral polymerase L is the sole vRNPs component responsible for Rab11a recognition: immunoprecipitation of L specifically co-precipitates HA-tagged Rab11a, whereas other vRNPs proteins show no interaction. In vitro binding studies confirm that L interacts directly and specifically with the active, GTP-bound form of Rab11a with sub-micromolar affinity. Domain mapping using truncated constructs reveals that this interaction requires the C-terminal methyltransferase and CTD domains of L (residues 1756-2165) and depends on Rab11a's Switch I region, known to mediate interactions with cellular Rab11a partners. Mutagenesis further highlights leucine 1860 in the L polymerase as critical for Rab11a binding. Competitive inhibition of the interaction between Rab11a and L using the minimal Rab11a-binding domain significantly impairs vRNP dynamics during infection, indicating that Rab11a-L binding is involved in the transport of vRNPs. Together, these findings establish RSV polymerase L as the key mediator of Rab11a engagement, define the molecular interface of their interaction, and reveal a potentially conserved viral strategy for genome transport. Targeting the L-Rab11a interaction could therefore be a promising strategy for the development of RSV-specific or broad-spectrum antiviral therapies.

rab GTP-Binding Proteins↗

PubMed2026

Bipolar disorder-associated variants in RAB5A disrupt its function in endolysosomal trafficking in fruit fly and mammalian systems.

Bipolar disorder is a severe neuropsychiatric disorder associated with significant morbidity and mortality. Although the heritability of bipolar disorder is among the highest of all neuropsychiatric disorders, the specific genetic etiologies for most affected individuals have remained elusive. This is due, in part, to difficulty confirming pathogenicity of genomic variants identified in bipolar disorder populations. From the Bipolar Exomes Browser (BipEX) project, we identified three missense variants in RAB5A in four individuals with bipolar disorder not found in controls. We used a Drosophila overexpression system to evaluate these bipolar disorder-associated variants in RAB5A. We determined that when bipolar disorder-associated RAB5A variants are expressed in fruit flies, synaptic neurotransmission, endolysosomal trafficking, viability, survival and wing morphology are all disrupted. We confirmed that certain bipolar disorder-associated RAB5A variants also disrupt early endosomal trafficking in mammalian cells. This confirms bipolar disorder-associated variants in RAB5A disrupt its normal function. Moreover, Drosophila melanogaster is a viable experimental system to test the pathogenicity of genomic variants associated with psychiatric disorders.

Journal Article↗