GIMAP6 is required for T cell maintenance and efficient autophagy in mice

Investigation and verification of GIMAP6 as a robust biomarker for prognosis and tumor immunity in lung adenocarcinoma

BACKGROUND AND AIM

According to previous reports, GTPase of immunity-associated protein 6 (GIMAP6) is essential for autophagy. However, it is unclear how GIMAP6 affects the development and tumor immunity of lung adenocarcinoma (LUAD).

METHODS

In the present study, the role of GIMAP6 in vivo and in vitro was examined using reverse transcription-quantitative PCR, western blotting, and Cell Counting Kit-8, colony formation and Transwell assays. Datasets from The Cancer Genome Atlas and Genotype-Tissue Expression databases were thoroughly analyzed using R software. A nomogram was created using GIMAP6 and prognostic characteristics. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and Gene Set Enrichment Analysis were applied to explore the potential mechanism of GIMAP6 in lung cancer. The link between GIMAP6 and the immunological landscape was studied using single-cell RNA sequencing datasets from Tumor Immune Estimation Resource (TIMER) 2.0 and Tumor Immune Single-cell Hub.

RESULTS

Patients with high GIMAP6 expression had improved overall and disease-specific survival compared with those patients with low GIMAP6 expression. According to the receiver operating characteristic and calibration curve, the nomogram based on T stage, N stage and GIMAP6 had predictive value for prognosis. According to functional enrichment analysis, GIMAP6 was primarily involved in T-cell receptor signaling pathway, chemokine signaling pathway, cytokine and cytokine receptor interaction. GIMAP6 was shown to be favorably linked with the infiltration of immune cells and immune-related molecules, including cytotoxic T-lymphocyte associated protein 4, programmed death-ligand 1, and T cell immunoreceptor with Ig and ITIM domains, by single-cell sequencing and TIMER2.0 analysis. The role of GIMAP6 in lung cancer cell proliferation, invasion, migration and immunity was experimentally verified.

CONCLUSION

These findings confirmed that GIMAP6 was an effective prognostic molecule that was involved in the regulation of the immune microenvironment of LUAD, and may become a predictor for the efficacy of immunotherapy.

GIMAP6 regulates autophagy, immune competence, and inflammation in mice and humans

Inborn errors of immunity (IEIs) unveil regulatory pathways of human immunity. We describe a new IEI caused by mutations in the GTPase of the immune-associated protein 6 (GIMAP6) gene in patients with infections, lymphoproliferation, autoimmunity, and multiorgan vasculitis. Patients and Gimap6^−/− mice show defects in autophagy, redox regulation, and polyunsaturated fatty acid (PUFA)–containing lipids. We find that GIMAP6 complexes with GABARAPL2 and GIMAP7 to regulate GTPase activity. Also, GIMAP6 is induced by IFN-γ and plays a critical role in antibacterial immunity. Finally, we observed that Gimap6^−/− mice died prematurely from microangiopathic glomerulosclerosis most likely due to GIMAP6 deficiency in kidney endothelial cells.

Identification of Biomarkers Associated With CD4+ T-Cell Infiltration With Gene Coexpression Network in Dermatomyositis

Background

Dermatomyositis is an autoimmune disease characterized by damage to the skin and muscles. CD4⁺ T cells are of crucial importance in the occurrence and development of dermatomyositis (DM). However, there are few bioinformatics studies on potential pathogenic genes and immune cell infiltration of DM. Therefore, this study intended to explore CD4⁺ T-cell infiltration–associated key genes in DM and construct a new model to predict the level of CD4⁺ T-cell infiltration in DM.

Methods

GSE46239, GSE142807, GSE1551, and GSE193276 datasets were downloaded. The WGCNA and CIBERSORT algorithms were performed to identify the most correlated gene module with CD4⁺ T cells. Matascape was used for GO enrichment and KEGG pathway analysis of the key gene module. LASSO regression analysis was used to identify the key genes and construct the prediction model. The correlation between the key genes and CD4⁺ T-cell infiltration was investigated. GSEA was performed to research the underlying signaling pathways of the key genes. The key gene-correlated transcription factors were identified through the RcisTarget and Gene-motif rankings databases. The miRcode and DIANA-LncBase databases were used to build the lncRNA-miRNA-mRNA network.

Results

In the brown module, 5 key genes (chromosome 1 open reading frame 106 (C1orf106), component of oligomeric Golgi complex 8 (COG8), envoplakin (EVPL), GTPases of immunity-associated protein family member 6 (GIMAP6), and interferon-alpha inducible protein 6 (IFI6)) highly associated with CD4⁺ T-cell infiltration were identified. The prediction model was constructed and showed better predictive performance in the training set, and this satisfactory model performance was validated in another skin biopsy dataset and a muscle biopsy dataset. The expression levels of the key genes promoted the CD4⁺ T-cell infiltration. GSEA results revealed that the key genes were remarkably enriched in many immunity-associated pathways, such as JAK/STAT signaling pathway. The cisbp_M2205, transcription factor-binding site, was enriched in C1orf106, EVPL, and IF16. Finally, 3,835 lncRNAs and 52 miRNAs significantly correlated with key genes were used to build a ceRNA network.

Conclusion

The C1orf106, COG8, EVPL, GIMAP6, and IFI6 genes are associated with CD4⁺ T-cell infiltration. The prediction model constructed based on the 5 key genes may better predict the level of CD4⁺ T-cell infiltration in damaged muscle and lesional skin of DM. These key genes could be recognized as potential biomarkers and immunotherapeutic targets of DM.

Patchy Distribution of GTPases of Immunity Associated Proteins (GIMAP) within Cnidarians and Dinoflagellates Suggests a Complex Evolutionary History

GTPases of Immunity-Associated Proteins (GIMAP) are a group of small GTP-binding proteins found in a variety of organisms, including vertebrates, invertebrates, and plants. These proteins are characterized by the highly conserved AIG1 domain, and in vertebrates, have been implicated in regulation of the immune system as well as apoptosis and autophagy, though their exact mechanism of action remains unclear. Recent work on cnidarian GIMAPs suggests a conserved role in immunity, apoptosis, and autophagy—three processes involved in coral bleaching, or the breakdown of cnidarian-dinoflagellate symbiosis. Therefore, to further understand the evolution of GIMAPs in this group of organisms, the purpose of this study was to characterize GIMAP or GIMAP-like sequences utilizing publicly available genomic and transcriptomic data in species across the cnidarian phylogeny. The results revealed a patchy distribution of GIMAPs in cnidarians, with three distinct types referred to as L-GIMAP, S-GIMAP, and GIMAP-like. Additionally, GIMAPs were present in most dinoflagellate species and formed seven well-supported clades. Overall, these results elucidate the distribution of GIMAPs within two distantly related eukaryotic groups and represent the first in-depth investigation on the evolution of these proteins within both protists and basal metazoans.

Topical Application of Temperature-Sensitive Gel Containing Caerin 1.1 and 1.9 Peptides on TC-1 Tumour-Bearing Mice Induced High-Level Immune Response in the Tumour Microenvironment

The development of topical cream drugs that increase the immune activation of tumour-infiltrating lymphocytes against tumour and chronic viral infection-associated lesions is of great immunotherapeutic significance. This study demonstrates that the topical application of a temperature-sensitive gel containing caerin 1.1 and 1.9 peptides reduces nearly 50% of the tumour weight of HPV16 E6/E7-transformed TC-1 tumour-bearing mice via improving the tumour microenvironment. Confocal microscopy confirms the time-dependent penetration of caerin 1.9 through the epidermal layer of the ear skin structure of mice. Single-cell transcriptomic analysis shows that the caerin 1.1/1.9 gel expands the populations with high immune activation level and largely stimulates the pro-inflammatory activity of NK and dendritic cells. Closely associated with INFα response, Cebpb seems to play a key role in altering the function of all Arg1^hi macrophages in the caerin group. In addition, the caerin gel treatment recruits almost two-fold more activated CD8⁺ T cells to the TME, relative to the untreated tumour, which shows a synergistic effect derived from the regulation of S1pr1, Ccr7, Ms4a4b and Gimap family expression. The TMT10plex-labelling proteomic quantification further demonstrates the activation of interferon-alpha/beta secretion and response to cytokine stimulus by the caerin gel, while the protein contents of several key regulators were elevated by more than 30%, such as Cd5l, Gzma, Ifit1, Irf9 and Stat1. Computational integration of the proteome with the single-cell transcriptome consistently suggested greater activation of NK and T cells with the topical application of caerin peptide gel.

The GIMAP Family Proteins: An Incomplete Puzzle

Overview: Long-term survival of T lymphocytes in quiescent state is essential to maintain their cell numbers in secondary lymphoid organs and in peripheral circulation. In the BioBreeding diabetes-prone strain of rats (BB-DP), loss of functional GIMAP5 (GTPase of the immune associated nucleotide binding protein 5) results in profound peripheral T lymphopenia. This discovery heralded the identification of a new family of proteins initially called Immune-associated nucleotide binding protein (IAN) family. In this review we will use ‘GIMAP’ to refer to this family of proteins. Recent studies suggest that GIMAP proteins may interact with each other and also be involved in the movement of the cellular cargo along the cytoskeletal network. Here we will summarize the current knowledge on the characteristics and functions of GIMAP family of proteins.

A human case of GIMAP6 deficiency: a novel primary immune deficiency

The GTPase of immunity-associated proteins (GIMAPs) are a family of genes believed to contribute to lymphocyte development, signaling, and apoptosis, thus playing an important role in immune system homeostasis. While models of gene derangement have been described in both mice and immortalized cell lines, human examples of these diseases remain exceptionally rare. In this manuscript we describe the first documented human cases of a homozygous deleterious GIMAP6 variant in the GIMAP6 gene and their subsequent clinical and immunological phenotype. In order to interrogate the patients’ immune defect, we performed whole-exome sequencing, western blot, flow cytometry analysis, lymphocyte activation and proliferation studies, cytokine release assays, and apoptosis studies. We found two siblings with a predicted deleterious homozygous variant in the GIMAP6 gene with no expression of GIMAP6 protein on western blot. Patients demonstrated accelerated apoptosis, but largely normal lymphocyte subpopulations, activation and proliferation and cytokine release. There appears to be a spectrum of clinical features associated with deficiency of GIMAP6 protein, with one patient suffering lymphopenia and recurrent sinopulmonary infections, and the other clinically asymptomatic. Biallelic variants in the GIMAP6 gene have now been shown to demonstrate disease in humans. The absence of GIMAP6 protein is associated with a spectrum of clinical manifestations and much remains to be learnt about the pathogenic mechanisms underlying this disease. We suggest that biallelic variants in the gene for GIMAP6 should be considered in children with lymphopenia and recurrent sinopulmonary infections.

Differential expression of Exaiptasia pallida GIMAP genes upon induction of apoptosis and autophagy suggests a potential role in cnidarian symbiosis and disease

Coral reefs, one of the world's most productive and diverse ecosystems, are currently threatened by a variety of stressors that result in increased prevalence of both bleaching and disease. Therefore, understanding the molecular mechanisms involved in these responses is critical to mitigate future damage to the reefs. One group of genes that is potentially involved in cnidarian immunity and symbiosis is GTPases of immunity associated proteins (GIMAP). In vertebrates, this family of proteins is involved in regulating the fate of developing lymphocytes and interacts with proteins involved in apoptosis and autophagy. As apoptosis, autophagy and immunity have previously been shown to be involved in cnidarian symbiosis and disease, the goal of this research was to determine the role of cnidarian GIMAPs in these processes using the anemone Exaiptasia pallida To do so, GIMAP genes were characterized in the E. pallida genome and changes in gene expression were measured using qPCR in response to chemical induction of apoptosis, autophagy and treatment with the immune stimulant lipopolysaccharide (LPS) in both aposymbiotic and symbiotic anemones. The results revealed four GIMAP-like genes in E. pallida, referred to as Ep_GIMAPs Induction of apoptosis and autophagy resulted in a general downregulation of Ep_GIMAPs, but no significant changes were observed in response to LPS treatment. This indicates that Ep_GIMAPs may be involved in the regulation of apoptosis and autophagy, and therefore could play a role in cnidarian-dinoflagellate symbiosis. Overall, these results increase our knowledge on the function of GIMAPs in a basal metazoan.

Transcriptomic study in women with trisomy 21 identifies a possible role of the GTPases of the immunity-associated proteins (GIMAP) in the protection of breast cancer

BACKGROUND

People with trisomy 21 (T21) are predisposed to developing hematological tumors, but have significantly lower-than-expected age-adjusted incidence rates of having a solid tumor.

MATERIAL AND METHODS

To identify novel genetic factors implicated in the lower breast cancer (BC) frequency observed in women with T21 than in the general population, we compared the transcriptome pattern of women with a homogeneous T21, aged more than 30 years, with or without BC, and tumoral BC tissue of control women with a normal karyotype from the study of Varley et al. (2014).

RESULTS

Differential analysis of gene expression between the 15 women in the T21 without BC group and BC patients in the other groups (two women with T21 and fifteen control women, respectively) revealed 154 differentially expressed genes, of which 63 were found to have similar expression profile (up- or downregulated). Of those 63 genes, four were in the same family, namely GIMAP4, GIMAP6, GIMAP7 and GIMAP8, and were strongly upregulated in the T21 without BC group compared to the other groups. A significant decrease in mRNA levels of these genes in BC tissues compared to non-tumor breast tissues was also noted.

CONCLUSION

We found that the expression of some GIMAPs is significantly higher in women with T21 without BC than in patients with sporadic BC. Our findings support the hypothesis that GIMAPs may play a tumor-suppressive role against BC, and open the possibility that they may also have the same role for other solid tumors in T21 patients. The search for new prognostic factors and hopefully new therapeutic or preventive strategies against BC are discussed.

Egyptian Rousette IFN-ω Subtypes Elicit Distinct Antiviral Effects and Transcriptional Responses in Conspecific Cells

Bats host a number of viruses that cause severe disease in humans without experiencing overt symptoms of disease themselves. While the mechanisms underlying this ability to avoid sickness are not known, deep sequencing studies of bat genomes have uncovered genetic adaptations that may have functional importance in the antiviral response of these animals. Egyptian rousette bats (Rousettus aegyptiacus) are the natural reservoir hosts of Marburg virus (MARV). In contrast to humans, these bats do not become sick when infected with MARV. A striking difference to the human genome is that Egyptian rousettes have an expanded repertoire of IFNW genes. To probe the biological implications of this expansion, we synthesized IFN-ω4 and IFN-ω9 proteins and tested their antiviral activity in Egyptian rousette cells. Both IFN-ω4 and IFN-ω9 showed antiviral activity against RNA viruses, including MARV, with IFN-ω9 being more efficient than IFN-ω4. Using RNA-Seq, we examined the transcriptional response induced by each protein. Although the sets of genes induced by the two IFNs were largely overlapping, IFN-ω9 induced a more rapid and intense response than did IFN-ω4. About 13% of genes induced by IFN-ω treatment are not found in the Interferome or other ISG databases, indicating that they may be uniquely IFN-responsive in this bat.