Coronin-1A links cytoskeleton dynamics to TCR alpha beta-induced cell signaling

T cell population size control by coronin 1 uncovered: from a spot identified by two-dimensional gel electrophoresis to quantitative proteomics

INTRODUCTION

Recent work identified members of the evolutionarily conserved coronin protein family as key regulators of cell population size. This work originated ~25 years ago through the identification, by two-dimensional gel electrophoresis, of coronin 1 as a host protein involved in the virulence of Mycobacterium tuberculosis. We here describe the journey from a spot on a 2D gel to the recent realization that coronin proteins represent key controllers of eukaryotic cell population sizes, using ever more sophisticated proteomic techniques.

AREAS COVERED

We discuss the value of 'old school' proteomics using relatively simple and cost-effective technologies that allowed to gain insights into subcellular proteomes and describe how label-free quantitative (phospho)proteomics using mass spectrometry allowed to disentangle the role for coronin 1 in eukaryotic cell population size control. Finally, we mention potential implications of coronin-mediated cell population size control for health and disease.

EXPERT OPINION

Proteome analysis has been revolutionized by the advent of modern-day mass spectrometers and is indispensable for a better understanding of biology. Here, we discuss how careful dissection of physio-pathological processes by a combination of proteomics, genomics, biochemistry and cell biology may allow to zoom in on the unexplored, thereby possibly tackling hitherto unasked questions and defining novel mechanisms.

TRIM4 enhances small-molecule-induced neddylated-degradation of CORO1A for triple negative breast cancer therapy

Background: As a critical member of the Coronin family, Coronin 1A (CORO1A) plays a crucial role in the progression of triple-negative breast cancer (TNBC). However, CORO1A is typically considered "undruggable" due to its smooth surface and complex protein-protein interactions (PPIs). Molecular glues have emerged as one of the most effective strategies to rapidly degrade such "undruggable" targets. Neddylation, an emerging approach, has shown promise in targeting pathogenic proteins for degradation through the NEDD8 pathway, making the degradation of CORO1A an attractive pharmacological strategy. Methods: A phenotypic drug screening strategy coupled with multi-omics approaches was utilized to rapidly identify a molecular glue degrader for CORO1A and to uncover the associated mechanisms. The Omics and Text-based Target Enrichment and Ranking (OTTER) tools, co-immunoprecipitation (Co-IP) assay, mass spectrometry, and the separation of phases-based protein interaction reporter (SPPIER) method were employed to explore the interaction between Aurovertin B (AB) and CORO1A via TRIM4. The pharmacological effects of AB were assessed using TNBC patient-derived organoids (PDOs) and 3D bioprinting models. Results: We identified AB as a previously undisclosed molecular glue that significantly promotes the neddylation and proteasomal degradation of CORO1A via TRIM4, an atypical E3 ligase. Notably, the degradation of CORO1A markedly inhibited various cellular processes and exerted robust antitumor effects in TNBC PDOs and 3D bioprinting models. Conclusions: Our findings underscore the critical role of CORO1A in TNBC and lay a crucial foundation for the development of innovative drugs based on molecular glue technology.

Coronin 1-dependent cell density sensing and regulation of the peripheral T cell population size

The establishment and maintenance of peripheral T cells is important to ensure appropriate immunity. In mammals, T cells are produced in the thymus before seeding the periphery early in life, and thereafter progressive thymus involution impairs new T cell production. Yet, peripheral T cells are maintained lifelong at approximately similar cell numbers. The question thus arises: what are the mechanisms that enable the maintenance of the appropriate number of circulating T cells, ensuring that T cell numbers are neither too low nor too high? Here, we highlight recent research suggesting a key role for coronin 1, a member of the evolutionarily conserved family of coronin proteins, in both allowing T cells to reach as well as maintain their appropriate cell population size. This cell population size controlling pathway was found to be conserved in amoeba, mice and human. We propose that coronin 1 is an integral part of a cell-intrinsic pathway that couples cell density information with prosurvival signalling thereby regulating the appropriate number of peripheral T cells.

β-Actin G342D as a Cause of NK Cell Deficiency Impairing Lytic Synapse Termination

NK cell deficiency (NKD) occurs when an individual's major clinical immunodeficiency derives from abnormal NK cells and is associated with several genetic etiologies. Three categories of β-actin-related diseases with over 60 ACTB (β-actin) variants have previously been identified, none with a distinct NK cell phenotype. An individual with mild developmental delay, macrothrombocytopenia, and susceptibility to infections, molluscum contagiosum virus, and EBV-associated lymphoma had functional NKD for over a decade. A de novo ACTB variant encoding G342D β-actin was identified and was consistent with the individual's developmental and platelet phenotype. This novel variant also was found to have direct impact in NK cells because its expression in the human NK cell line YTS (YTS-NKD) caused increased cell spreading in lytic immune synapses created on activating surfaces. YTS-NKD cells were able to degranulate and perform cytotoxicity, but they demonstrated defective serial killing because of prolonged conjugation to the killed target cell and thus were effectively unable to terminate lytic synapses. G342D β-actin results in a novel, to our knowledge, mechanism of functional NKD via increased synaptic spreading and defective lytic synapse termination with resulting impaired serial killing, leading to overall reductions in NK cell cytotoxicity.

The Actin Regulators Involved in the Function and Related Diseases of Lymphocytes

Actin is an important cytoskeletal protein involved in signal transduction, cell structure and motility. Actin regulators include actin-monomer-binding proteins, Wiskott-Aldrich syndrome (WAS) family of proteins, nucleation proteins, actin filament polymerases and severing proteins. This group of proteins regulate the dynamic changes in actin assembly/disassembly, thus playing an important role in cell motility, intracellular transport, cell division and other basic cellular activities. Lymphocytes are important components of the human immune system, consisting of T-lymphocytes (T cells), B-lymphocytes (B cells) and natural killer cells (NK cells). Lymphocytes are indispensable for both innate and adaptive immunity and cannot function normally without various actin regulators. In this review, we first briefly introduce the structure and fundamental functions of a variety of well-known and newly discovered actin regulators, then we highlight the role of actin regulators in T cell, B cell and NK cell, and finally provide a landscape of various diseases associated with them. This review provides new directions in exploring actin regulators and promotes more precise and effective treatments for related diseases.

Coronin 1A facilitates calcium mobilization and promotes astrocyte reactivity in HIV-1 neuropathogenesis

Astrocyte reactivity, a phenomenon observed in a variety of neurodegenerative disorders, can have both beneficial and detrimental manifestations which significantly affect neuronal physiology. In neuroAIDS, reactive astrocytes have been observed to severely affect the neuronal population present in their vicinity. Calcium signaling plays a central role in mediating astrocyte reactivity. Coronin 1A, an actin-binding protein, majorly reported in hematopoietic cells, regulates cell activity in a calcium-dependent manner, but its role in astrocyte physiology and reactivity is largely unknown. Using a well-characterized primary culture of human astroglia and neurons, we explored the roles of coronin 1A in astrocyte physiology and its involvement in facilitating astrocyte reactivity. In this study, we report coronin 1A expression in human primary astrocytes and autopsy brain sections, and that it plays activity-dependent roles by facilitating calcium mobilization from the intracellular stores. HIV-1 Tat, a potent neurotoxicant that turns astrocytes reactive, augments coronin 1A expression, apart from affecting GFAP and pro-inflammatory molecules. Also, the autopsy brain tissue of HIV-1 infected individuals has a higher expression of coronin 1A. Downregulation of coronin 1A attenuated the HIV-1 Tat-induced deleterious effects of reactive astrocytes, measured as the upregulated expression of GFAP, pro-inflammatory molecules, and enhanced release of IL-6, and hence reduced astrocyte-mediated neurodegeneration. Our findings also suggest that out of a pool of dysregulated miRNAs studied by us, hsa-miR-92b-5p regulates coronin 1A expression under the effect of HIV-1 Tat. These findings highlight the novel roles of coronin 1A in regulating astrocyte activity in stimulated conditions and astrocyte reactivity observed in HIV-1 neuropathogenesis.

Actin Dynamics at the T Cell Synapse as Revealed by Immune-Related Actinopathies

The actin cytoskeleton is composed of dynamic filament networks that build adaptable local architectures to sustain nearly all cellular activities in response to a myriad of stimuli. Although the function of numerous players that tune actin remodeling is known, the coordinated molecular orchestration of the actin cytoskeleton to guide cellular decisions is still ill defined. T lymphocytes provide a prototypical example of how a complex program of actin cytoskeleton remodeling sustains the spatio-temporal control of key cellular activities, namely antigen scanning and sensing, as well as polarized delivery of effector molecules, via the immunological synapse. We here review the unique knowledge on actin dynamics at the T lymphocyte synapse gained through the study of primary immunodeficiences caused by mutations in genes encoding actin regulatory proteins. Beyond the specific roles of individual actin remodelers, we further develop the view that these operate in a coordinated manner and are an integral part of multiple signaling pathways in T lymphocytes.

Wnt5a regulates Ameloblastoma Cell Migration by modulating Mitochondrial and Cytoskeletal Dynamics

Objective: Abnormal expression of Wnt5a has been detected in various tumors, including ameloblastoma (AB). Yet, there is no specific mechanistic evidence for the functional role of Wnt5a in AB. In this study, we aimed to conduct a mechanistic examination of the importance of Wnt5a in AB development. Methods: The expressions of Wnt5a and Coro1A were examined by Western blot and immunohistochemistry both in AB tissues and AM-1 cells. The number and size of mitochondria were detected by electronic transmission microscope and confocal microscope. Gain-of-function and loss-of-function assays were used to explore the biological roles of Wnt5a and Coro1A in organelle dynamics changes and cell migration. Cell migration was detected by wound healing and transwell assay. Results: We found that in AM-1 cells, up-regulation of Wnt5a led to enhanced mitochondrial energy production and altered calcium homeostasis, with elevated calcium levels directly leading to altered mitochondrial dynamics and interactions between the cytoskeleton and the mitochondria. When Wnt5a or its downstream cytoskeleton-associated protein Coro1A was knocked down, the migration capacity of AM-1 cells was markedly impaired. Conclusion: Together, these results suggest that Wnt5a plays mitochondria and cytoskeleton specific roles in regulating the development of human AB, with its down-regulation leading to impaired tumor development, thus highlighting Wnt5a or Coro1A as potentially viable therapeutic targets for the treatment of AB.

Omics-wide quantitative B-cell infiltration analyses identify GPR18 for human cancer prognosis with superiority over CD20

Tumor-infiltrating B lymphocyte (TIL-B), and TIL-B-related biomarkers have clinical prognostic values for human cancers. CD20 (encoded by MS4A1) is a widely used TIL-B biomarker. Using TCGA-quantitative multiomics datasets, we first cross-compare prognostic powers of intratumoral CD20 protein, mRNA and TIL-B levels in pan-cancers. Here, we show that MS4A1 and TIL-B are consistently prognostic in 5 cancers (head and neck, lung, cervical, kidney and low-grade glioma), while unexpectedly, CD20 protein levels lack quantitative correlations with MS4A1/TIL-B levels and demonstrate limited prognosticity. Subsequent bioinformatics discovery for TIL-B prognostic gene identifies a single gene, GPR18 with stand-alone prognosticity across 9 cancers (superior over CD20), with further validations in multiple non-TCGA cohorts. GPR18's immune signature denotes major B-cell-T-cell interactions, with its intratumoral expression strongly tied to a "T-cell active", likely cytolytic, status across human cancers, suggesting its functional link to cytolytic T-cell activity in cancer. GPR18 merits biological and clinical utility assessments over CD20.

The relevance between the immune response-related gene module and clinical traits in head and neck squamous cell carcinoma

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer in the world, accounting for more than 90% of head and neck malignant tumors. However, its molecular mechanism is largely unknown. To help elucidate the potential mechanism of HNSCC tumorigenesis, we investigated the gene interaction patterns associated with tumorigenesis.

METHODS

Weighted gene co-expression network analysis (WGCNA) can help us to predict the intrinsic relationship or correlation between gene expression. Additionally, we further explored the combination of clinical information and module construction.

RESULTS

Sixteen modules were constructed, among which the key module most closely associated with clinical information was identified. By analyzing the genes in this module, we found that the latter may be related to the immune response, inflammatory response and formation of the tumor microenvironment. Sixteen hub genes were identified-ARHGAP9, SASH3, CORO1A, ITGAL, PPP1R16B, TBC1D10C, IL10RA, ITK, AKNA, PRKCB, TRAF3IP3, GIMAP4, CCR7, P2RY8, GIMAP7, and SP140. We further validated these genes at the transcriptional and translation levels.

CONCLUSION

The innovative use of a weighted network to analyze HNSCC samples provides new insights into the molecular mechanism and prognosis of HNSCC. Additionally, the hub genes we identified can be used as biomarkers and therapeutic targets of HNSCC, laying the foundation for the accurate diagnosis and treatment of HNSCC in clinical and research in the future.

Molecular Classification of Primary Immunodeficiencies of T Lymphocytes

Proper regulation of the immune system is required for protection against pathogens and preventing autoimmune disorders. Inborn errors of the immune system due to inherited or de novo germline mutations can lead to the loss of protective immunity, aberrant immune homeostasis, and the development of autoimmune disease, or combinations of these. Forward genetic screens involving clinical material from patients with primary immunodeficiencies (PIDs) can vary in severity from life-threatening disease affecting multiple cell types and organs to relatively mild disease with susceptibility to a limited range of pathogens or mild autoimmune conditions. As central mediators of innate and adaptive immune responses, T cells are critical orchestrators and effectors of the immune response. As such, several PIDs result from loss of or altered T cell function. PID-associated functional defects range from complete absence of T cell development to uncontrolled effector cell activation. Furthermore, the gene products of known PID causal genes are involved in diverse molecular pathways ranging from T cell receptor signaling to regulators of protein glycosylation. Identification of the molecular and biochemical cause of PIDs can not only guide the course of treatment for patients, but also inform our understanding of the basic biology behind T cell function. In this chapter, we review PIDs with known genetic causes that intrinsically affect T cell function with particular focus on perturbations of biochemical pathways.

Coronins and their role in immunological phenomena

Coronins are a large family of proteins occurring in many eukaryotes. In mammals, seven coronin genes have been identified, evidencing that coronins 1 to 6 present classic coronin structure, while coronin 7 is a tandem coronin particle, without a spiral domain, although the best characterised coronin, in terms of both structure and function, is the mammalian coronin 1. It has been proven that they are related to regulation of actin dynamics, e.g. as a result of interaction with the complex of proteins Arp2/3. These proteins also modulate the activity of immune system cells, including lymphocyte T and B cells, neutrophils and macrophages. They are involved in bacterial infections with Mycobacterium tuberculosis, M. leprae and Helicobacter pylori and participate in the response to viral infections, e.g. infections of lymphocytic choriomeningitis virus (LCMV) and vesicular stomatitis Indiana virus (VSV). Also their involvement in autoimmune diseases such as lupus erythematosus has been recorded.

Severe Epstein-Barr virus infection in primary immunodeficiency and the normal host

Epstein-Barr virus (EBV) infection is ubiquitous in humans, but the majority of infections have an asymptomatic or self-limiting clinical course. Rarely, individuals may develop a pathological EBV infection with a variety of life threatening complications (including haemophagocytosis and malignancy) and others develop asymptomatic chronic EBV viraemia. Although an impaired ability to control EBV infection has long been recognised as a hallmark of severe T-cell immunodeficiency, the advent of next generation sequencing has identified a series of Primary Immunodeficiencies in which EBV-related pathology is the dominant feature. Chronic active EBV infection is defined as chronic EBV viraemia associated with systemic lymphoproliferative disease, in the absence of immunodeficiency. Descriptions of larger cohorts of patients with chronic active EBV in recent years have significantly advanced our understanding of this clinical syndrome. In this review we summarise the current understanding of the pathophysiology and natural history of these diseases and clinical syndromes, and discuss approaches to the investigation and treatment of severe or atypical EBV infection.

Proof of Principle for a T Lymphocyte Intrinsic Function of Coronin 1A

Coronins are evolutionarily conserved proteins that were originally identified as modulators of actin-dependent processes. Studies analyzing complete Coronin 1a knock-out mice have shown that this molecule is an important regulator of naive T cell homeostasis and it has been linked to immune deficiencies as well as autoimmune disorders. Nevertheless, because Coronin 1A is strongly expressed in all leukocyte subsets, it is not conclusive whether or not this phenotype is attributed to a T cell-intrinsic function of Coronin 1A. To address this research question, we have generated a T cell-specific Coronin 1a knock-out mouse (Coro1afl/fl × Cd4[Cre]). Deletion of Coronin 1A specifically in T cells led to a strong reduction in T cell number and a shift toward the effector/memory phenotype in peripheral lymphoid organs when compared with Cd4[Cre] mice expressing wild-type Coronin 1A. In contrast to peripheral lymphoid tissue, thymocyte number and subsets were not affected by the deletion of Coronin 1a Furthermore, T cell-specific Coronin 1a knock-out mice were largely resistant to the induction of autoimmunity when tested in the myelin oligoglycoprotein-induced EAE mouse model of multiple sclerosis. Thus, the phenotype of T cell-specific Coronin 1a deletion resembles the phenotype observed with conventional (whole body) Coronin 1a knock-out mice. In summary, our findings provide formal proof of the predominant T cell-intrinsic role of Coronin 1A.

Computational spatiotemporal analysis identifies WAVE2 and cofilin as joint regulators of costimulation-mediated T cell actin dynamics

Fluorescence microscopy is one of the most important tools in cell biology research because it provides spatial and temporal information to investigate regulatory systems inside cells. This technique can generate data in the form of signal intensities at thousands of positions resolved inside individual live cells. However, given extensive cell-to-cell variation, these data cannot be readily assembled into three- or four-dimensional maps of protein concentration that can be compared across different cells and conditions. We have developed a method to enable comparison of imaging data from many cells and applied it to investigate actin dynamics in T cell activation. Antigen recognition in T cells by the T cell receptor (TCR) is amplified by engagement of the costimulatory receptor CD28. We imaged actin and eight core actin regulators to generate over a thousand movies of T cells under conditions in which CD28 was either engaged or blocked in the context of a strong TCR signal. Our computational analysis showed that the primary effect of costimulation blockade was to decrease recruitment of the activator of actin nucleation WAVE2 (Wiskott-Aldrich syndrome protein family verprolin-homologous protein 2) and the actin-severing protein cofilin to F-actin. Reconstitution of WAVE2 and cofilin activity restored the defect in actin signaling dynamics caused by costimulation blockade. Thus, we have developed and validated an approach to quantify protein distributions in time and space for the analysis of complex regulatory systems.

Recurrent viral infections associated with a homozygous CORO1A mutation that disrupts oligomerization and cytoskeletal association

BACKGROUND

Coronin-1A (CORO1A) is a regulator of actin dynamics important for T-cell homeostasis. CORO1A deficiency causes T(-)B(+) natural killer-positive severe combined immunodeficiency or T-cell lymphopenia with severe viral infections. However, because all known human mutations in CORO1A abrogate protein expression, the role of the protein's functional domains in host immunity is unknown.

OBJECTIVE

We sought to identify the cause of the primary immunodeficiency in 2 young adult siblings with a history of disseminated varicella, cutaneous warts, and CD4(+) T-cell lymphopenia.

METHODS

We performed immunologic, genetic, and biochemical studies in the patients, family members, and healthy control subjects.

RESULTS

Both patients had CD4(+) T-cell lymphopenia and decreased lymphocyte proliferation to mitogens. IgG, IgM, IgA, and specific antibody responses were normal. Whole-genome sequencing identified a homozygous frameshift mutation in CORO1A disrupting the last 2 C-terminal domains by replacing 61 amino acids with a novel 91-amino-acid sequence. The CORO1A(S401fs) mutant was expressed in the patients' lymphocytes at a level comparable with that of wild-type CORO1A in normal lymphocytes but did not oligomerize and had impaired cytoskeletal association. CORO1A(S401fs) was associated with increased filamentous actin accumulation in T cells, severely defective thymic output, and impaired T-cell survival but normal calcium flux and cytotoxicity, demonstrating the importance of CORO1A oligomerization and subcellular localization in T-cell homeostasis.

CONCLUSIONS

We describe a truncating mutation in CORO1A that permits protein expression and survival into young adulthood. Our studies demonstrate the importance of intact CORO1A C-terminal domains in thymic egress and T-cell survival, as well as in defense against viral pathogens.

F-actin remodeling defects as revealed in primary immunodeficiency disorders

Primary immunodeficiencies (PIDs) are a heterogeneous group of immune-related diseases. PIDs develop due to defects in gene-products that have consequences to immune cell function. A number of PID-proteins is involved in the remodeling of filamentous actin (f-actin) to support the generation of a contact zone between the antigen-specific T cell and antigen presenting cell (APC): the immunological synapse (IS). IS formation is the first step towards T-cell activation and essential for clonal expansion and acquisition of effector function. We here evaluated PIDs in which aberrant f-actin-driven IS formation may contribute to the PID disease phenotypes as seen in patients. We review examples of such contributions to PID phenotypes from literature, and highlight cases in which PID-proteins were evaluated for a role in f-actin polymerization and IS formation. We conclude with the proposition that patient groups might benefit from stratifying them in distinct functional groups in regard to their f-actin remodeling phenotypes in lymphocytes.

Comprehensive Proteomic and Metabolomic Signatures of Nontypeable Haemophilus influenzae-Induced Acute Otitis Media Reveal Bacterial Aerobic Respiration in an Immunosuppressed Environment

A thorough understanding of the molecular details of the interactions between bacteria and host are critical to ultimately prevent disease. Recent technological advances allow simultaneous analysis of host and bacterial protein and metabolic profiles from a single small tissue sample to provide insight into pathogenesis. We used the chinchilla model of human otitis media to determine, for the first time, the most expansive delineation of global changes in protein and metabolite profiles during an experimentally induced disease. After 48 h of infection with nontypeable Haemophilus influenzae, middle ear tissue lysates were analyzed by high-resolution quantitative two-dimensional liquid chromatography-tandem mass spectrometry. Dynamic changes in 105 chinchilla proteins and 66 metabolites define the early proteomic and metabolomic signature of otitis media. Our studies indicate that establishment of disease coincides with actin morphogenesis, suppression of inflammatory mediators, and bacterial aerobic respiration. We validated the observed increase in the actin-remodeling complex, Arp2/3, and experimentally showed a role for Arp2/3 in nontypeable Haemophilus influenzae invasion. Direct inhibition of actin branch morphology altered bacterial invasion into host epithelial cells, and is supportive of our efforts to use the information gathered to modify outcomes of disease. The twenty-eight nontypeable Haemophilus influenzae proteins identified participate in carbohydrate and amino acid metabolism, redox homeostasis, and include cell wall-associated metabolic proteins. Quantitative characterization of the molecular signatures of infection will redefine our understanding of host response driven developmental changes during pathogenesis. These data represent the first comprehensive study of host protein and metabolite profiles in vivo in response to infection and show the feasibility of extensive characterization of host protein profiles during disease. Identification of novel protein targets and metabolic biomarkers will advance development of therapeutic and diagnostic options for treatment of disease.

T Lymphocyte Migration: An Action Movie Starring the Actin and Associated Actors

The actin cytoskeleton is composed of a dynamic filament meshwork that builds the architecture of the cell to sustain its fundamental properties. This physical structure is characterized by a continuous remodeling, which allows cells to accomplish complex motility steps such as directed migration, crossing of biological barriers, and interaction with other cells. T lymphocytes excel in these motility steps to ensure their immune surveillance duties. In particular, actin cytoskeleton remodeling is a key to facilitate the journey of T lymphocytes through distinct tissue environments and to tune their stop and go behavior during the scanning of antigen-presenting cells. The molecular mechanisms controlling actin cytoskeleton remodeling during T lymphocyte motility have been only partially unraveled, since the function of many actin regulators has not yet been assessed in these cells. Our review aims to integrate the current knowledge into a comprehensive picture of how the actin cytoskeleton drives T lymphocyte migration. We will present the molecular actors that control actin cytoskeleton remodeling, as well as their role in the different T lymphocyte motile steps. We will also highlight which challenges remain to be addressed experimentally and which approaches appear promising to tackle them.

The disease-linked Glu-26-Lys mutant version of Coronin 1A exhibits pleiotropic and pathway-specific signaling defects

Coronin 1A is involved in cell shape dynamics and Rac1 GTPase signaling. Loss-of-function mutations in the Coro1A gene promote severe immunodeficiency. An immunodeficiency-linked Coro1A point mutant is described that becomes dysfunctional due to changes in actin-binding, actin-remodeling, and signaling activities.

Coronin 1A (Coro1A) is involved in cytoskeletal and signaling events, including the regulation of Rac1 GTPase– and myosin II–dependent pathways. Mutations that generate truncated or unstable Coro1A proteins cause immunodeficiencies in both humans and rodents. However, in the case of the peripheral T-cell–deficient (Ptcd) mouse strain, the immunodeficiency is caused by a Glu-26-Lys mutation that targets a surface-exposed residue unlikely to affect the intramolecular architecture and stability of the protein. Here we report that this mutation induces pleiotropic effects in Coro1A protein, including the exacerbation of Coro1A-dependent actin-binding and -bundling activities; the formation of large meshworks of Coro1A^E26K-decorated filaments endowed with unusual organizational, functional, and staining properties; and the elimination of Coro1A functions associated with both Rac1 and myosin II signaling. By contrast, it does not affect the ability of Coro1A to stimulate the nuclear factor of activated T-cells (NF-AT). Coro1A^E26K is not a dominant-negative mutant, indicating that its pathological effects are derived from the inability to rescue the complete loss of the wild-type counterpart in cells. These results indicate that Coro1A^E26K behaves as either a recessive gain-of-function or loss-of-function mutant protein, depending on signaling context and presence of the wild-type counterpart in cells.

The expanding spectrum of human coronin 1A deficiency

Since the first discovery of coronin in the amoeba Dictyostelium discoideum, remarkable insights have been gained regarding the structure and function of coronins, highly conserved from yeast to humans. It has been speculated that coronins have evolved from actin-binding molecules in lower eukaryotes to regulators of various cellular processes in mammals. Indeed, coronins are not only involved in cytokinesis, cell motility, and other actin-related processes but they are also implicated in immune homeostasis and calcium-calcineurin signaling. Most strikingly, coronin 1 deficiencies give rise to immune deficiencies in mice and humans that are characterized by severe T lymphocytopenia. Whereas complete absence of coronin 1A is associated with severe combined immunodeficiency in humans, hypomorphic mutations lead to a profound defect in naïve T cells, expansion of oligoclonal memory T cells, and exquisite susceptibility to EBV-associated B cell lymphoproliferation. Recent publications show that coronin 1A also plays a role in natural killer cell cytotoxic function and in neurobehavioral processes. It can be expected that future identification of coronin 1A-deficient patients will further extend the phenotypic spectrum thereby increasing our knowledge of this fascinating molecule.

Molecular mechanisms and functional implications of polarized actin remodeling at the T cell immunological synapse

Transient,specialized cell-cell interactions play a central role in leukocyte function by enabling specific intercellular communication in the context of a highly dynamic systems level response. The dramatic structural changes required for the formation of these contacts are driven by rapid and precise cytoskeletal remodeling events. In recent years, the immunological synapse that forms between a T lymphocyte and its antigen-presenting target cell has emerged as an important model system for understanding immune cell interactions. In this review, we discuss how regulators of the cortical actin cytoskeleton control synaptic architecture and in this way specify T cell function.

Compound heterozygous CORO1A mutations in siblings with a mucocutaneous-immunodeficiency syndrome of epidermodysplasia verruciformis-HPV, molluscum contagiosum and granulomatous tuberculoid leprosy

PURPOSE

Coronin-1A deficiency is a recently recognized autosomal recessive primary immunodeficiency caused by mutations in CORO1A (OMIM 605000) that results in T-cell lymphopenia and is classified as T(-)B(+)NK(+)severe combined immunodeficiency (SCID). Only two other CORO1A-kindred are known to date, thus the defining characteristics are not well delineated. We identified a unique CORO1A-kindred.

METHODS

We captured a 10-year analysis of the immune-clinical phenotypes in two affected siblings from disease debut of age 7 years. Target-specific genetic studies were pursued but unrevealing. Telomere lengths were also assessed. Whole exome sequencing (WES) uncovered the molecular diagnosis and Western blot validated findings.

RESULTS

We found the compound heterozygous CORO1A variants: c.248_249delCT (p.P83RfsX10) and a novel mutation c.1077delC (p.Q360RfsX44) (NM_007074.3) in two affected non-consanguineous siblings that manifested as absent CD4CD45RA(+) (naïve) T and memory B cells, low NK cells and abnormally increased double-negative (DN) ϒδ T-cells. Distinguishing characteristics were late clinical debut with an unusual mucocutaneous syndrome of epidermodysplasia verruciformis-human papilloma virus (EV-HPV), molluscum contagiosum and oral-cutaneous herpetic ulcers; the older female sibling also had a disfiguring granulomatous tuberculoid leprosy. Both had bilateral bronchiectasis and the female died of EBV+ lymphomas at age 16 years. The younger surviving male, without malignancy, had reproducibly very short telomere lengths, not before appreciated in CORO1A mutations.

CONCLUSION

We reveal the third CORO1A-mutated kindred, with the immune phenotype of abnormal naïve CD4 and DN T-cells and newfound characteristics of a late/hypomorphic-like SCID of an EV-HPV mucocutaneous syndrome with also B and NK defects and shortened telomeres. Our findings contribute to the elucidation of the CORO1A-SCID-CID spectrum.

Porcine coronin 1A contributes to nuclear factor-kappa B (NF-κB) inactivation during Haemophilus parasuis infection

Haemophilus parasuis (H.parasuis) is the etiological agent of porcine polyserositis and arthritis (Glässer's disease) characterized by fibrinous polyserositis, meningitis and polyarthritis, causing severe economic losses to the swine industry. Currently, the molecular basis of this infection is largely unkonwn. Coronin 1A (Coro1A) plays important roles in host against bacterial infection, yet little is known about porcine Coro1A. In this study, we investigated the molecular characterization of porcine Coro1A, revealing that porcine Coro1A was widely expressed in different tissues. Coro1A could be induced by lipopolysaccharide (LPS), polyinosinic acid-polycytidylic acid [poly (I:C)] and H.parasuis in porcine kidney-15 (PK-15) cells. Functional analyses revealed that porcine Coro1A suppressed the NF-κB activation during H.parasuis infection by inhibiting the degradation of IκBα and nuclear translocation of p65. Overexpression of porcine Coro1A inhibited the transcription of NF-κB-mediated downstream genes [Interleukin-6 (IL-6), Interleukin-8 (IL-8) and COX-2] through down-regulation of NF-κB. The results indicated that porcine Coro1A is an important immunity related gene that helps to inhibit NF-kB activation during H. parasuis infection.

Coronin1 proteins dictate rac1 intracellular dynamics and cytoskeletal output

Rac1 regulates lamellipodium formation, myosin II-dependent contractility, and focal adhesions during cell migration. While the spatiotemporal assembly of those processes is well characterized, the signaling mechanisms involved remain obscure. We report here that the cytoskeleton-related Coronin1A and -1B proteins control a myosin II inactivation-dependent step that dictates the intracellular dynamics and cytoskeletal output of active Rac1. This step is signaling-branch specific, since it affects the functional competence of active Rac1 only when forming complexes with downstream ArhGEF7 and Pak proteins in actomyosin-rich structures. The pathway is used by default unless Rac1 is actively rerouted away from the structures by upstream activators and signals from other Rho GTPases. These results indicate that Coronin1 proteins are at the center of a regulatory hub that coordinates Rac1 activation, effector exchange, and the F-actin organization state during cell signaling. Targeting this route could be useful to hamper migration of cancer cells harboring oncogenic RAC1 mutations.

Coronin3 regulates gastric cancer invasion and metastasis by interacting with Arp2

Coronin3 expression is increased in gastric cancer (GC) tissues and can promote GC invasion and metastasis. However, the mechanisms underlying Coronin3 function in GC remain unclear. In this study, we aimed to explore the interacting molecules essential for the tumor-promoting effects of Coronin3 in GC. Using mass spectrometric analysis, functional studies, and immunohistochemistry, we found that Arp2 interacted with Coronin3, and ectopic expression of Arp2 promoted GC cell migration and invasion, while Arp2 knockdown suppressed whole-cell motility and attenuated the Coronin3-mediated upregulation of cell migration and invasion. In addition, both proteins correlated with the metastatic status of GC patients. Furthermore, survival analyses demonstrated that both Coronin3 and Arp2 correlated with overall GC patient survival, and the combination of Coronin3 and Arp2 most accurately predicted GC patient prognosis. Combined, these data demonstrate that Coronin3 can regulate GC invasion and metastasis through Arp2, and the combination of Coronin3 and Arp2 provides a potential marker for predicting GC prognosis.

The actin-driven spatiotemporal organization of T-cell signaling at the system scale

T cells are activated through interaction with antigen-presenting cells (APCs). During activation, receptors and signaling intermediates accumulate in diverse spatiotemporal distributions. These distributions control the probability of signaling interactions and thus govern information flow through the signaling system. Spatiotemporally resolved system-scale investigation of signaling can extract the regulatory information thus encoded, allowing unique insight into the control of T-cell function. Substantial technical challenges exist, and these are briefly discussed herein. While much of the work assessing T-cell spatiotemporal organization uses planar APC substitutes, we focus here on B-cell APCs with often stark differences. Spatiotemporal signaling distributions are driven by cell biologically distinct structures, a large protein assembly at the interface center, a large invagination, the actin-supported interface periphery as extended by smaller individual lamella, and a newly discovered whole-interface actin-driven lamellum. The more than 60 elements of T-cell activation studied to date are dynamically distributed between these structures, generating a complex organization of the signaling system. Signal initiation and core signaling prefer the interface center, while signal amplification is localized in the transient lamellum. Actin dynamics control signaling distributions through regulation of the underlying structures and drive a highly undulating T-cell/APC interface that imposes substantial constraints on T-cell organization. We suggest that the regulation of actin dynamics, by controlling signaling distributions and membrane topology, is an important rheostat of T-cell signaling.

Orchestrating cytoskeleton and intracellular vesicle traffic to build functional immunological synapses

Immunological synapses are specialized cell-cell contacts formed between T lymphocytes and antigen-presenting cells. They are induced upon antigen recognition and are crucial for T-cell activation and effector functions. The generation and function of immunological synapses depend on an active T-cell polarization process, which results from a finely orchestrated crosstalk between the antigen receptor signal transduction machinery, the actin and microtubule cytoskeletons, and controlled vesicle traffic. Although we understand how some of these particular events are regulated, we still lack knowledge on how these multiple cellular elements are harmonized to ensure appropriate T-cell responses. We discuss here our view on how T-cell receptor signal transduction initially commands cytoskeletal and vesicle traffic polarization, which in turn sets the immunological synapse molecular design that regulates T-cell activation. We also discuss how the human immunodeficiency virus (HIV-1) hijacks some of these processes impairing immunological synapse generation and function.

Lytic immune synapse function requires filamentous actin deconstruction by Coronin 1A

Lytic immune effector function depends upon directed secretion of cytolytic granules at the immunological synapse (IS) and requires dynamic rearrangement of filamentous (F)-actin. Coronin 1A (Coro1A) is the hematopoietic-specific member of the Coronin family of actin regulators that promote F-actin disassembly. Here, we show that Coro1A is required for natural killer (NK) cell cytotoxic function in two human NK cell lines and ex vivo cells from a Coro1A-deficient patient. Using superresolution nanoscopy to probe the IS, we demonstrate that Coro1A promotes the deconstruction of F-actin density that facilitates effective delivery of lytic granules to the IS. Thus, we show, for the first time to our knowledge, a critical role for F-actin deconstruction in cytotoxic function and immunological secretion and identify Coro1A as its mediator.

Cell biological steps and checkpoints in accessing NK cell cytotoxicity

Natural killer (NK) cell-mediated cytotoxicity is governed by the formation of a lytic immune synapse in discrete regulated steps, which give rise to an extensive array of cellular checkpoints in accessing NK cell-mediated cytolytic defense. Appropriate progression through these cell biological steps is critical for the directed secretion of specialized secretory lysosomes and subsequent target cell death. Here we highlight recent discoveries in the formation of the NK cell cytolytic synapse as well as the molecular steps and cell biological checkpoints required for this essential host defense process.

ZCH-2B8a, an antibody targeting actin-binding protein coronin-1a, is a potential therapeutic agent for B-lineage malignancies

BACKGROUND

Monoclonal antibody (mAb)-based targeted therapy is one of the most promising strategies to cure cancers. MAb ZCH-2B8a (2B8a) was a novel antibody generated in our laboratory, which presented potential to be a therapeutic agent for hematologic malignancies.

METHODS

We investigated the reactivity profile of 2B8a mAb, identified the targeting antigen by proteomic and genetic approaches and evaluated its potential to exert tumor cell killing.

RESULTS

2B8a antigen was strictly expressed on lymph tissues and hematopoietic cells (mainly leukocytes), and was highly expressed on B-lineage leukemia cell lines and acute lymphoblastic leukemia (ALL) cells from patients. 2B8a antibody was quickly internalized into the target cells once binding to the antigen, but was capable of killing tumor cells through complement dependent cytotoxicity. To identify the 2B8a antigen, the proteins of Raji cells were immunoprecipitated with 2B8a antibody and analyzed by mass spectrometry, which indicated that coronin-1a was a potential candidate. Then, coronin-1a gene was cloned from Raji cells, inserted into plasmid pcDNA3.1 (+), and transfected into CHO cells. The intracellular 2B8a antigen level was significantly increased in the coronin-1a transfectant cell line.

CONCLUSION

2B8a mAb is a novel antibody targeting coronin-1a, which has the potential to be a therapeutic agent for B-lineage malignancies.

Quantitative proteomics in resected renal cancer tissue for biomarker discovery and profiling

Background:

Proteomics-based approaches for biomarker discovery are promising strategies used in cancer research. We present state-of-art label-free quantitative proteomics method to assess proteome of renal cell carcinoma (RCC) compared with noncancer renal tissues.

Methods:

Fresh frozen tissue samples from eight primary RCC lesions and autologous adjacent normal renal tissues were obtained from surgically resected tumour-bearing kidneys. Proteins were extracted by complete solubilisation of tissues using filter-aided sample preparation (FASP) method. Trypsin digested proteins were analysed using quantitative label-free proteomics approach followed by data interpretation and pathways analysis.

Results:

A total of 1761 proteins were identified and quantified with high confidence (MASCOT ion score threshold of 35 and P-value <0.05). Of these, 596 proteins were identified as differentially expressed between cancer and noncancer tissues. Two upregulated proteins in tumour samples (adipose differentiation-related protein and Coronin 1A) were further validated by immunohistochemistry. Pathway analysis using IPA, KOBAS 2.0, DAVID functional annotation and FLink tools showed enrichment of many cancer-related biological processes and pathways such as oxidative phosphorylation, glycolysis and amino acid synthetic pathways.

Conclusions:

Our study identified a number of differentially expressed proteins and pathways using label-free proteomics approach in RCC compared with normal tissue samples. Two proteins validated in this study are the focus of on-going research in a large cohort of patients.

Combined immunodeficiencies with nonfunctional T lymphocytes

Immunodeficiencies with nonfunctional T cells comprise a heterogeneous group of conditions characterized by altered function of T lymphocytes in spite of largely preserved T cell development. Some of these forms are due to hypomorphic mutations in genes causing severe combined immunodeficiency. More recently, advances in human genome sequencing have facilitated the identification of novel genetic defects that do not affect T cell development, but alter T cell function and homeostasis. Along with increased susceptibility to infections, these conditions are characterized by autoimmunity and higher risk of malignancies. The study of these diseases, and of corresponding animal models, has provided fundamental insights on the mechanisms that govern immune homeostasis.

On guard: coronin proteins in innate and adaptive immunity

Recent work has implicated members of the evolutionarily conserved family of coronin proteins - in particular coronin 1 - in immune homeostasis. Coronins are involved in processes as diverse as pathogen survival in phagocytes and homeostatic T cell signalling. Notably, in both mice and humans, coronin mutations are associated with immune deficiencies and resistance to autoimmunity. In this article, we review what is currently known about these conserved molecules and discuss a potential common mechanism that underlies their diverse activities, which seem to involve cytoskeletal interactions as well as calcium-calcineurin signalling.

Primary immunodeficiencies predisposed to Epstein-Barr virus-driven haematological diseases

Epstein-Barr virus (EBV), a ubiquitous human herpesvirus, maintains lifelong subclinical persistent infections in humans. In the circulation, EBV primarily infects the B cells, and protective immunity is mediated by EBV-specific cytotoxic T cells (CTLs) and natural killer (NK) cells. However, EBV has been linked to several devastating diseases, such as haemophagocytic lymphohistiocytosis (HLH) and lymphoproliferative diseases in the immunocompromised host. Some types of primary immunodeficiencies (PIDs) are characterized by the development of EBV-associated complications as their predominant clinical feature. The study of such genetic diseases presents an ideal opportunity for a better understanding of the biology of the immune responses against EBV. Here, we summarize the range of PIDs that are predisposed to EBV-associated haematological diseases, describing their clinical picture and pathogenetic mechanisms.

Whole-exome sequencing identifies Coronin-1A deficiency in 3 siblings with immunodeficiency and EBV-associated B-cell lymphoproliferation

BACKGROUND

Primary immunodeficiencies are a rare group of inborn diseases characterized by a broad clinical and genetic heterogeneity. Substantial advances in the identification of the underlying molecular mechanisms can be achieved through the study of patients with increased susceptibility to specific infections and immune dysregulation. We evaluated 3 siblings from a consanguineous family presenting with EBV-associated B-cell lymphoproliferation at an early age (12, 7½, and 14 months, respectively) and profound naive T-cell lymphopenia.

OBJECTIVE

On the basis of the hypothesis of a rare inborn immunodeficiency of autosomal recessive inheritance, we sought to characterize the underlying genetic defect.

METHODS

We performed genome-wide homozygosity mapping, followed by whole-exome sequencing.

RESULTS

We identified a homozygous inherited missense mutation in the gene encoding Coronin-1A (CORO1A) in the 3 siblings. This mutation, p. V134M, results in the substitution of an evolutionarily conserved amino acid within the β-propeller domain, which abrogates almost completely the protein expression in the patients' cells. In addition to a significant diminution of naive T-cell numbers, we found impaired development of a diverse T-cell repertoire, near-to-absent invariant natural killer T cells, and severely diminished mucosal-associated invariant T cell numbers.

CONCLUSIONS

Our findings define a new clinical entity of a primary immunodeficiency with increased susceptibility to EBV-induced lymphoproliferation in patients associated with hypomorphic Coronin-1A mutation.

T cell antigen receptor activation and actin cytoskeleton remodeling

T cells constitute a crucial arm of the adaptive immune system and their optimal function is required for a healthy immune response. After the initial step of T cell-receptor (TCR) triggering by antigenic peptide complexes on antigen presenting cell (APC), the T cell exhibits extensive cytoskeletal remodeling. This cytoskeletal remodeling leads to the formation of an "immunological synapse" [1] characterized by regulated clustering, segregation and movement of receptors at the interface. Synapse formation regulates T cell activation and response to antigenic peptides and proceeds via feedback between actin cytoskeleton and TCR signaling. Actin polymerization participates in various events during the synapse formation, maturation, and eventually its disassembly. There is increasing knowledge about the actin effectors that couple TCR activation to actin rearrangements [2,3], and how defects in these effectors translate into impairment of T cell activation. In this review we aim to summarize and integrate parts of what is currently known about this feedback process. In addition, in light of recent advancements in our understanding of TCR triggering and translocation at the synapse, we speculate on the organizational and functional diversity of microfilament architecture in the T cell. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.

Partial defects of T-cell development associated with poor T-cell function

For many years, severe combined immune deficiency diseases, which are characterized by virtual lack of circulating T cells and severe predisposition to infections since early in life, have been considered the prototypic forms of genetic defects of T-cell development. More recently, advances in genome sequencing have allowed identification of a growing number of gene defects that cause severe but incomplete defects in T-cell development, function, or both. Along with recurrent and severe infections, especially cutaneous viral infections, the clinical phenotype of these conditions is characterized by prominent immune dysregulation.

Transcriptome analysis of spermatogenically regressed, recrudescent and active phase testis of seasonally breeding wall lizards Hemidactylus flaviviridis

BACKGROUND

Reptiles are phylogenically important group of organisms as mammals have evolved from them. Wall lizard testis exhibits clearly distinct morphology during various phases of a reproductive cycle making them an interesting model to study regulation of spermatogenesis. Studies on reptile spermatogenesis are negligible hence this study will prove to be an important resource.

METHODOLOGY/PRINCIPAL FINDINGS

Histological analyses show complete regression of seminiferous tubules during regressed phase with retracted Sertoli cells and spermatognia. In the recrudescent phase, regressed testis regain cellular activity showing presence of normal Sertoli cells and developing germ cells. In the active phase, testis reaches up to its maximum size with enlarged seminiferous tubules and presence of sperm in seminiferous lumen. Total RNA extracted from whole testis of regressed, recrudescent and active phase of wall lizard was hybridized on Mouse Whole Genome 8×60 K format gene chip. Microarray data from regressed phase was deemed as control group. Microarray data were validated by assessing the expression of some selected genes using Quantitative Real-Time PCR. The genes prominently expressed in recrudescent and active phase testis are cytoskeleton organization GO 0005856, cell growth GO 0045927, GTpase regulator activity GO: 0030695, transcription GO: 0006352, apoptosis GO: 0006915 and many other biological processes. The genes showing higher expression in regressed phase belonged to functional categories such as negative regulation of macromolecule metabolic process GO: 0010605, negative regulation of gene expression GO: 0010629 and maintenance of stem cell niche GO: 0045165.

CONCLUSION/SIGNIFICANCE

This is the first exploratory study profiling transcriptome of three drastically different conditions of any reptilian testis. The genes expressed in the testis during regressed, recrudescent and active phase of reproductive cycle are in concordance with the testis morphology during these phases. This study will pave the way for deeper insight into regulation and evolution of gene regulatory mechanisms in spermatogenesis.

Functional T cell immunodeficiencies (with T cells present)

Severe combined immunodeficiency (SCID) comprises a group of disorders that are fatal owing to genetic defects that abrogate T cell development. Numerous related defects have recently been identified that allow T cell development but that compromise T cell function by affecting proximal or distal steps in intracellular signaling. These functional T cell immunodeficiencies are characterized by immune dysregulation and increased risk of malignancies, in addition to infections. The study of patients with these rare conditions, and of corresponding animal models, illustrates the importance of intracellular signaling to maintain T cell homeostasis.

Constitutive turnover of phosphorylation at Thr-412 of human p57/coronin-1 regulates the interaction with actin

The actin-binding protein p57/coronin-1, a member of the coronin protein family, is selectively expressed in hematopoietic cells and plays crucial roles in the immune response through reorganization of the actin cytoskeleton. We previously reported that p57/coronin-1 is phosphorylated by protein kinase C, and the phosphorylation down-regulates the association of this protein with actin. In this study we analyzed the phosphorylation sites of p57/coronin-1 derived from HL60 human leukemic cells by MALDI-TOF-MS, two-dimensional gel electrophoresis, and Phos-tag® acrylamide gel electrophoresis in combination with site-directed mutagenesis and identified Ser-2 and Thr-412 as major phosphorylation sites. A major part of p57/coronin-1 was found as an unphosphorylated form in HL60 cells, but phosphorylation at Thr-412 of p57/coronin-1 was detected after the cells were treated with calyculin A, a Ser/Thr phosphatase inhibitor, suggesting that p57/coronin-1 undergoes constitutive turnover of phosphorylation/dephosphorylation at Thr-412. A diphosphorylated form of p57/coronin-1 was detected after the cells were treated with phorbol 12-myristate 13-acetate plus calyculin A. We then assessed the effects of phosphorylation at Thr-412 on the association of p57/coronin-1 with actin. A co-immunoprecipitation experiment with anti-p57/coronin-1 antibodies and HL60 cell lysates revealed that β-actin was co-precipitated with the unphosphorylated form but not with the phosphorylated form at Thr-412 of p57/coronin-1. Furthermore, the phosphorylation mimic (T412D) of p57/coronin-1 expressed in HEK293T cells exhibited lower affinity for actin than the wild-type or the unphosphorylation mimic (T412A) did. These results indicate that the constitutive turnover of phosphorylation at Thr-412 of p57/coronin-1 regulates its interaction with actin.

Antigen processing and presentation by dendritic cells is independent of coronin 1

Coronin 1, which is a member of the evolutionary conserved coronin protein family that is highly expressed in all leukocytes is involved in the activation of the Ca(2+)/calcineurin signaling pathway following cell surface stimulation in T cells, B cells as well as macrophages. Mice deficient for coronin 1 have strongly reduced peripheral T cell numbers as a result of a lack of pro-survival signals for naïve T cells. Whether or not impaired antigen processing and presentation in the absence of coronin 1 expression contributes to this reduction of T cell numbers is unknown. We here show that coronin 1-deficient bone marrow-derived dendritic cells develop normally, and that wild type and coronin 1-deficient dendritic cells were equally able to induce antigen-specific proliferation of T cells. Furthermore, upon immunization, in vivo proliferation of adoptively transferred antigen-specific T cells was comparable in wild type and coronin 1-deficient mice. Finally, infection of wild type and coronin 1-deficient dendritic cells with an ovalbumin-expressing Listeria monocytogenes strain induced comparable levels of ovalbumin-specific T cells responses. Together these results suggest that coronin 1 is dispensable for antigen processing and presentation by dendritic cells.

Experimental assessment of the contribution of electrodynamic interactions to long-distance recruitment of biomolecular partners: Theoretical basis

Highly specific spatiotemporal interactions between cognate molecular partners essentially sustain all biochemical transactions in living matter. That such an exquisite level of accuracy may result from encountering forces solely driven by thermal diffusive processes is unlikely. Here we propose a yet unexplored strategy to experimentally tackle the long-standing question of a possibly active recruitment at a distance of cognate partners of biomolecular reactions via the action of resonant electrodynamic interactions. We considered two simplified models for a preliminary feasibility investigation of the devised methodology. By taking advantage of advanced experimental techniques nowadays available, we propose to measure the characteristic encounter time scales of dually interacting biopartners and to compare them with theoretical predictions worked out in both the presence and absence of putative long-range electromagnetic forces.

GRAIL (gene related to anergy in lymphocytes) regulates cytoskeletal reorganization through ubiquitination and degradation of Arp2/3 subunit 5 and coronin 1A

Anergy is an important mechanism for the maintenance of peripheral tolerance and avoidance of autoimmunity. The up-regulation of E3 ubiqitin ligases, including GRAIL (gene related to anergy in lymphocytes), is a key event in the induction and preservation of anergy in T cells. However, the mechanisms of GRAIL-mediated anergy induction are still not completely understood. We examined which proteins serve as substrates for GRAIL in anergic T cells. Arp2/3-5 (actin-related protein 2/3 subunit 5) and coronin 1A were polyubiquitinated by GRAIL via Lys-48 and Lys-63 linkages. In anergic T cells and GRAIL-overexpressed T cells, the expression of Arp2/3-5 and coronin 1A was reduced. Furthermore, we demonstrated that GRAIL impaired lamellipodium formation and reduced the accumulation of F-actin at the immunological synapse. GRAIL functions via the ubiquitination and degradation of actin cytoskeleton-associated proteins, in particular Arp2/3-5 and coronin 1A. These data reveal that GRAIL regulates proteins involved in the actin cytoskeletal organization, thereby maintaining the unresponsive state of anergic T cells.