Human FCHO1 deficiency reveals role for clathrin-mediated endocytosis in development and function of T cells

Genomic Regions Associated with Resistance to Gastrointestinal Nematode Parasites in Sheep-A Review

Gastrointestinal nematodes (GINs) can be a major constraint and global challenge to the sheep industry. These nematodes infect the small intestine and abomasum of grazing sheep, causing symptoms such as weight loss, diarrhea, hypoproteinemia, and anemia, which can lead to death. The use of anthelmintics to treat infected animals has led to GIN resistance, and excessive use of these drugs has resulted in residue traced in food and the environment. Resistance to GINs can be measured using multiple traits, including fecal egg count (FEC), Faffa Malan Chart scores, hematocrit, packed cell volume, eosinophilia, immunoglobulin (Ig), and dagginess scores. Genetic variation among animals exists, and understanding these differences can help identify genomic regions associated with resistance to GINs in sheep. Genes playing important roles in the immune system were identified in several studies in this review, such as the CFI and MUC15 genes. Results from several studies showed overlapping quantitative trait loci (QTLs) associated with multiple traits measuring resistance to GINs, mainly FEC. The discovery of genomic regions, positional candidate genes, and QTLs associated with resistance to GINs can help increase and accelerate genetic gains in sheep breeding programs and reveal the genetic basis and biological mechanisms underlying this trait.

Causal effects of gut microbiota on sepsis and sepsis-related death: insights from genome-wide Mendelian randomization, single-cell RNA, bulk RNA sequencing, and network pharmacology

BACKGROUND

Gut microbiota alterations have been implicated in sepsis and related infectious diseases, but the causal relationship and underlying mechanisms remain unclear.

METHODS

We evaluated the association between gut microbiota composition and sepsis using two-sample Mendelian randomization (MR) analysis based on published genome-wide association study (GWAS) summary statistics. Sensitivity analyses were conducted to validate the robustness of the results. Reverse MR analysis and integration of GWAS and expression quantitative trait loci (eQTL) data were performed to identify potential genes and therapeutic targets.

RESULTS

Our analysis identified 11 causal bacterial taxa associated with sepsis, with increased abundance of six taxa showing positive causal relationships. Ten taxa had causal effects on the 28-day survival outcome of septic patients, with increased abundance of six taxa showing positive associations. Sensitivity analyses confirmed the robustness of these associations. Reverse MR analysis did not provide evidence of reverse causality. Integration of GWAS and eQTL data revealed 76 genes passing the summary data-based Mendelian randomization (SMR) test. Differential expression of these genes was observed between sepsis patients and healthy individuals. These genes represent potential therapeutic targets for sepsis. Molecular docking analysis predicted potential drug-target interactions, further supporting their therapeutic potential.

CONCLUSION

Our study provides insights for the development of personalized treatment strategies for sepsis and offers preliminary candidate targets and drugs for future drug development.

CamoTSS: analysis of alternative transcription start sites for cellular phenotypes and regulatory patterns from 5' scRNA-seq data

Five-prime single-cell RNA-seq (scRNA-seq) has been widely employed to profile cellular transcriptomes, however, its power of analysing transcription start sites (TSS) has not been fully utilised. Here, we present a computational method suite, CamoTSS, to precisely identify TSS and quantify its expression by leveraging the cDNA on read 1, which enables effective detection of alternative TSS usage. With various experimental data sets, we have demonstrated that CamoTSS can accurately identify TSS and the detected alternative TSS usages showed strong specificity in different biological processes, including cell types across human organs, the development of human thymus, and cancer conditions. As evidenced in nasopharyngeal cancer, alternative TSS usage can also reveal regulatory patterns including systematic TSS dysregulations.

FCH domain only 1 (FCHo1), a potential new biomarker for lung cancer

Lung carcinoma is the main reason for cancer-associated deaths in the world. In a previous study, FCH domain only 1 (FCHo1) which is managed by protein kinase B (AKT), was shown to be activated in lung cancer. FCHo1 knockdown has previously been shown to cause cell death in lung cancer. However, the specific roles of FCHo1 in lung carcinoma remain elusive. Herein, we propose that FCHo1's intracellular mechanism targets the G1 to S phase transition, following the M phase. We demonstrated that F-BAR and mu homology domains exist separately in human lung tissues and that one truncated form is not detected in patients with lung cancer. Furthermore, quantitative global proteome analysis of FCHo1 indicated that the inhibition of G1/S phase transition and FCHo1 RNAi led to the death of cells in the G1/S phase. Noninvasive viral aerosol-mediated delivery of FCHo1 shRNA suppressed cancer progression in mice with non-small-cell lung cancer (NSCLC), suggesting that the delivery of FCHo1 shRNA could be a meaningful therapeutic strategy in lung cancer. Additional studies are needed to make clear the detailed mechanism of action of FCHo1.

FCHO controls AP2's initiating role in endocytosis through a PtdIns(4,5)P2-dependent switch

Clathrin-mediated endocytosis (CME) is the main mechanism by which mammalian cells control their cell surface proteome. Proper operation of the pivotal CME cargo adaptor AP2 requires membrane-localized Fer/Cip4 homology domain-only proteins (FCHO). Here, live-cell enhanced total internal reflection fluorescence-structured illumination microscopy shows that FCHO marks sites of clathrin-coated pit (CCP) initiation, which mature into uniform-sized CCPs comprising a central patch of AP2 and clathrin corralled by an FCHO/Epidermal growth factor potential receptor substrate number 15 (Eps15) ring. We dissect the network of interactions between the FCHO interdomain linker and AP2, which concentrates, orients, tethers, and partially destabilizes closed AP2 at the plasma membrane. AP2's subsequent membrane deposition drives its opening, which triggers FCHO displacement through steric competition with phosphatidylinositol 4,5-bisphosphate, clathrin, cargo, and CME accessory factors. FCHO can now relocate toward a CCP's outer edge to engage and activate further AP2s to drive CCP growth/maturation.

Imaging vesicle formation dynamics supports the flexible model of clathrin-mediated endocytosis

Clathrin polymerization and changes in plasma membrane architecture are necessary steps in forming vesicles to internalize cargo during clathrin-mediated endocytosis (CME). Simultaneous analysis of clathrin dynamics and membrane structure is challenging due to the limited axial resolution of fluorescence microscopes and the heterogeneity of CME. This has fueled conflicting models of vesicle assembly and obscured the roles of flat clathrin assemblies. Here, using Simultaneous Two-wavelength Axial Ratiometry (STAR) microscopy, we bridge this critical knowledge gap by quantifying the nanoscale dynamics of clathrin-coat shape change during vesicle assembly. We find that de novo clathrin accumulations generate both flat and curved structures. High-throughput analysis reveals that the initiation of vesicle curvature does not directly correlate with clathrin accumulation. We show clathrin accumulation is preferentially simultaneous with curvature formation at shorter-lived clathrin-coated vesicles (CCVs), but favors a flat-to-curved transition at longer-lived CCVs. The broad spectrum of curvature initiation dynamics revealed by STAR microscopy supports multiple productive mechanisms of vesicle formation and advocates for the flexible model of CME.

Despite decades of research, the dynamics of clathrin-coated vesicle formation is ambiguous. Here, authors use STAR microscopy to quantify the nanoscale dynamics of vesicle formation, supporting the flexible model of clathrin-mediated endocytosis.

Are Alzheimer's and coronary artery diseases genetically related to longevity?

INTRODUCTION

In the last decade researchers have attempted to investigate the shared genetic architecture of longevity and age-related diseases and assess whether the increased longevity in certain people is due to protective alleles in the risk genes for a particular condition or whether there are specific "longevity" genes increasing the lifespan independently of age-related conditions' risk genes. The aim of this study was to investigate the shared genetic component between longevity and two age-related conditions.

METHODS

We performed a cross-trait meta-analysis of publicly available genome-wide data for Alzheimer's disease, coronary artery disease and longevity using a subset-based approach provided by the R package ASSET.

RESULTS

Despite the lack of strong genetic correlation between longevity and the two diseases, we identified 38 genome-wide significant lead SNPs across 22 independent genomic loci. Of them 6 were found to be potentially shared among the three traits mapping to genes including DAB2IP, DNM2, FCHO1, CLPTM1, and SNRPD2. We also identified 19 novel genome-wide associations for the individual traits in this study. Functional annotations and biological pathway enrichment analyses suggested that pleiotropic variants are involved in clathrin-mediated endocytosis and plasma lipoprotein and neurotransmitter clearance processes.

DISCUSSION

In summary, we have been able to advance in the knowledge of the genetic overlap existing among longevity and the two most common age-related disorders.

Mechanisms and functions of endocytosis in T cells

Once thought of primarily as a means to neutralize pathogens or to facilitate feeding, endocytosis is now known to regulate a wide range of eukaryotic cell processes. Among these are regulation of signal transduction, mitosis, lipid homeostasis, and directed migration, among others. Less well-appreciated are the roles various forms of endocytosis plays in regulating αβ and, especially, γδ T cell functions, such as T cell receptor signaling, antigen discovery by trogocytosis, and activated cell growth. Herein we examine the contribution of both clathrin-mediated and clathrin-independent mechanisms of endocytosis to T cell biology.

Antagonistic regulation controls clathrin-mediated endocytosis: AP2 adaptor facilitation vs restraint from clathrin light chains

Orchestration of a complex network of protein interactions drives clathrin-mediated endocytosis (CME). A central role for the AP2 adaptor complex beyond cargo recognition and clathrin recruitment has emerged in recent years. It is now apparent that AP2 serves as a pivotal hub for protein interactions to mediate clathrin coated pit maturation, and couples lattice formation to membrane deformation. As a key driver for clathrin assembly, AP2 complements the attenuating role of clathrin light chain subunits, which enable dynamic lattice rearrangement needed for budding. This review summarises recent insights into AP2 function with respect to CME dynamics and biophysics, and its relationship to the role of clathrin light chains in clathrin assembly.

The paradigm of hematological malignant versus non-malignant manifestations, driven by primary immunodeficiencies: a complex interplay

Hematological malignancies (HM) developed on underlying primary immunodeficiencies (PID) are rare and of unusual features. Differentiating between malignant and non-malignant lymphoproliferation in cases of pediatric hematology and oncology and revealing their molecular predisposition demonstrate the complex interplay between PID and HM. We retrospectively studied a case series of seven pediatric patients, all with PID with manifestations raising suspicion for HM or hypereosinophilic syndrome (HES) or confirmed HM of lymphoid origin. Combined immunodeficiency (CID) without detection of a known mutated gene or with ataxia-telangiectasia (AT), STAT3 gain of function (GOF), DOCK8 deficiency, and CTLA4 deficiency were diagnosed in three, one, one, one, and one patient, respectively. Acute lymphoblastic leukemia and Hodgkin lymphoma followed by second primary Burkitt lymphoma were diagnosed in one patient with CID each, while lymphomatoid granulomatosis in one patient with AT. Lymphoproliferative disease occurred in STAT3 GOF, CTLA4 deficiency and CID, one patient each, and idiopathic HES in DOCK8 deficiency (median age at presentation of PID or any hematological manifestation: four years). Four patients underwent hematopoietic cell transplantation (HCT) for STAT3 GOF, DOCK8 deficiency and CID in one, one, and two cases, respectively (median age: 10 years). At the last follow-up, all transplanted patients were alive. Reporting on patients' phenotype, genotype and course of disease shed light on the prevalence, characteristics, and pathophysiology of HM complicating PID. Discriminating the non-yet malignant lymphoproliferation from its malignant equivalent on the same pathophysiology background proved of additional value. Outcomes of PID after HCT, herein reported, are favorable.

Phenotypic Characteristics and Copy Number Variants in a Cohort of Colombian Patients with VACTERL Association

VACTERL association (OMIM 192350) is a heterogeneous clinical condition characterized by congenital structural defects that include at least 3 of the following features: vertebral abnormalities, anal atresia, heart defects, tracheoesophageal fistula, renal malformations, and limb defects. The nonrandom occurrence of these malformations and some familial cases suggest a possible association with genetic factors such as chromosomal alterations, gene mutations, and inherited syndromes such as Fanconi anemia (FA). In this study, the clinical phenotype and its relationship with the presence of chromosomal abnormalities and FA were evaluated in 18 patients with VACTERL association. For this, a G-banded karyotype, array-comparative genomic hybridization, and chromosomal fragility test for FA were performed. All patients (10 female and 8 male) showed a broad clinical spectrum: 13 (72.2%) had vertebral abnormalities, 8 (44.4%) had anal atresia, 14 (77.8%) had heart defects, 8 (44.4%) had esophageal atresia, 10 (55.6%) had renal abnormalities, and 10 (55.6%) had limb defects. Chromosomal abnormalities and FA were ruled out. In 2 cases, the finding of microalterations, namely del(15)(q11.2) and dup(17)(q12), explained the phenotype; in 8 cases, copy number variations were classified as variants of unknown significance and as not yet described in VACTERL. These variants comprise genes related to important cellular functions and embryonic development.

Beyond the Surface: Endocytosis of Mosquito-Borne Flaviviruses

Flaviviruses are a group of positive-sense RNA viruses that are primarily transmitted through arthropod vectors and are capable of causing a broad spectrum of diseases. Many of the flaviviruses that are pathogenic in humans are transmitted specifically through mosquito vectors. Over the past century, many mosquito-borne flavivirus infections have emerged and re-emerged, and are of global importance with hundreds of millions of infections occurring yearly. There is a need for novel, effective, and accessible vaccines and antivirals capable of inhibiting flavivirus infection and ameliorating disease. The development of therapeutics targeting viral entry has long been a goal of antiviral research, but most efforts are hindered by the lack of broad-spectrum potency or toxicities associated with on-target effects, since many host proteins necessary for viral entry are also essential for host cell biology. Mosquito-borne flaviviruses generally enter cells by clathrin-mediated endocytosis (CME), and recent studies suggest that a subset of these viruses can be internalized through a specialized form of CME that has additional dependencies distinct from canonical CME pathways, and antivirals targeting this pathway have been discovered. In this review, we discuss the role and contribution of endocytosis to mosquito-borne flavivirus entry as well as consider past and future efforts to target endocytosis for therapeutic interventions.

Matched Family Donor Lymphocyte Infusions as First Cellular Therapy for Patients with Severe Primary T Cell Deficiencies

Patients with primary immunodeficiencies caused by severe defects in T cell immunity are at risk of acquiring life-threatening infections. Cellular therapies are necessary to establish normal T cell function and to allow for long-term survival. This is most commonly achieved by hematopoietic stem cell transplantation (HSCT), but the outcome of this procedure is impaired if active infections are present at the time of HSCT. Donor lymphocyte infusions (DLIs) are a well-established therapeutic strategy following HSCT to treat viral infections, improve donor cell engraftment, or achieve graft-versus-leukemia activity in malignant disease. Here we present a cohort of 6 patients with primary T cell deficiencies who received transfusions of unselected mature donor lymphocytes prior and not directly related to allogeneic HSCT. DLIs obtained from the peripheral blood of HLA-identical (10/10) family donors were transfused without prior conditioning to treat or prevent life-threatening infections. All patients are alive with a follow-up of 0.5 to 16.5 years after the initial T cell administration. Additional cellular therapies were administered in 5 of 6 patients at 0.8 to 15 months after the first DLI. Mild cutaneous graft-versus-host disease (GVHD, stage ≤2) was observed in 3 of 6 patients and resolved spontaneously. We provide evidence that unselected HLA-identical DLIs can effectively prevent or contribute to overcome infections with a limited risk for GVHD in T cell deficient patients. The T cell system established by this readily available source can provide T cell function for years and can serve as a bridge to additional cellular therapies or, in specific conditions, as definite treatment.

Clathrin's life beyond 40: Connecting biochemistry with physiology and disease

Understanding of the range and mechanisms of clathrin functions has developed exponentially since clathrin's discovery in 1975. Here, newly established molecular mechanisms that regulate clathrin activity and connect clathrin pathways to differentiation, disease and physiological processes such as glucose metabolism are reviewed. Diversity and commonalities of clathrin pathways across the tree of life reveal species-specific differences enabling functional plasticity in both membrane traffic and cytokinesis. New structural information on clathrin coat formation and cargo interactions emphasises the interplay between clathrin, adaptor proteins, lipids and cargo, and how this interplay regulates quality control of clathrin's function and is compromised in infection and neurological disease. Roles for balancing clathrin-mediated cargo transport are defined in stem cell development and additional disease states.