Splicing factor SRSF1 controls T cell homeostasis and its decreased levels are linked to lymphopenia in systemic lupus erythematosus

Metabolic regulation of the immune system in health and diseases: mechanisms and interventions

Metabolism, including glycolysis, oxidative phosphorylation, fatty acid oxidation, and other metabolic pathways, impacts the phenotypes and functions of immune cells. The metabolic regulation of the immune system is important in the pathogenesis and progression of numerous diseases, such as cancers, autoimmune diseases and metabolic diseases. The concept of immunometabolism was introduced over a decade ago to elucidate the intricate interplay between metabolism and immunity. The definition of immunometabolism has expanded from chronic low-grade inflammation in metabolic diseases to metabolic reprogramming of immune cells in various diseases. With immunometabolism being proposed and developed, the metabolic regulation of the immune system can be gradually summarized and becomes more and more clearer. In the context of many diseases including cancer, autoimmune diseases, metabolic diseases, and many other disease, metabolic reprogramming occurs in immune cells inducing proinflammatory or anti-inflammatory effects. The phenotypic and functional changes of immune cells caused by metabolic regulation further affect and development of diseases. Based on experimental results, targeting cellular metabolism of immune cells becomes a promising therapy. In this review, we focus on immune cells to introduce their metabolic pathways and metabolic reprogramming, and summarize how these metabolic pathways affect immune effects in the context of diseases. We thoroughly explore targets and treatments based on immunometabolism in existing studies. The challenges of translating experimental results into clinical applications in the field of immunometabolism are also summarized. We believe that a better understanding of immune regulation in health and diseases will improve the management of most diseases.

The role of B-cell ferroptosis in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the dysregulation of B cell subpopulation and function. Recent studies have suggested a potential role of ferroptosis, an iron-dependent form of regulated cell death, in the pathogenesis of SLE. Here, we demonstrate that B-cell ferroptosis occurs both in lupus patients and MRL/lpr mice. Treatment with liproxstatin-1, a potent ferroptosis inhibitor, could reduce autoantibody production, improve renal damage, and alleviate lupus symptoms in vivo. Furthermore, our results suggest that ferroptosis may regulate B cell differentiation and plasma cell formation, indicating a potential mechanism for its involvement in SLE. Taken together, targeting ferroptosis in B cells may be a promising therapeutic strategy for SLE.

Towards understandings of serine/arginine-rich splicing factors

Serine/arginine-rich splicing factors (SRSFs) refer to twelve RNA-binding proteins which regulate splice site recognition and spliceosome assembly during precursor messenger RNA splicing. SRSFs also participate in other RNA metabolic events, such as transcription, translation and nonsense-mediated decay, during their shuttling between nucleus and cytoplasm, making them indispensable for genome diversity and cellular activity. Of note, aberrant SRSF expression and/or mutations elicit fallacies in gene splicing, leading to the generation of pathogenic gene and protein isoforms, which highlights the therapeutic potential of targeting SRSF to treat diseases. In this review, we updated current understanding of SRSF structures and functions in RNA metabolism. Next, we analyzed SRSF-induced aberrant gene expression and their pathogenic outcomes in cancers and non-tumor diseases. The development of some well-characterized SRSF inhibitors was discussed in detail. We hope this review will contribute to future studies of SRSF functions and drug development targeting SRSFs.

Estradiol in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune polymorphous disease that primarily affects women of reproductive age. This gender disparity has suggested the importance of investigating the role of reproductive hormones in the pathogenesis of the disease. Estradiol, the most potent form of estrogen, plays a key role in shaping the immune system including the production of lymphocytes, the peripheral differentiation of regulatory T cells (T-regs), antibody production, and the complement and interferon systems, and has been studied in the pathogenesis of systemic lupus erythematosus (SLE). It operates by binding to estrogen receptors (ERs) α and β, initiating cellular responses including alterations in gene expression. Regulatory T cells are instrumental in preserving immunological self-tolerance and moderating immune responses. Estradiol's serum levels correlate with the expansion of CD4+CD25+ and FoxP3+ in healthy females. However, this response is reduced in lupus patients. Estradiol also interacts with microRNAs (miRNAs) in gene regulation. Hsa-miR-10b-5p, a miRNA targeting SRSF1, is overexpressed in SLE patients and its levels increase with exposure to estrogens. Other miRNAs also show correlation with plasma Estradiol levels. The precise role of Estradiol in the pathogenesis of SLE remains complex and multifaceted and is a topic for further research.

Splicing factor SRSF1 deficiency in the liver triggers NASH-like pathology and cell death

Regulation of RNA processing contributes profoundly to tissue development and physiology. Here, we report that serine-arginine-rich splicing factor 1 (SRSF1) is essential for hepatocyte function and survival. Although SRSF1 is mainly known for its many roles in mRNA metabolism, it is also crucial for maintaining genome stability. We show that acute liver damage in the setting of targeted SRSF1 deletion in mice is associated with the excessive formation of deleterious RNA-DNA hybrids (R-loops), which induce DNA damage. Combining hepatocyte-specific transcriptome, proteome, and RNA binding analyses, we demonstrate that widespread genotoxic stress following SRSF1 depletion results in global inhibition of mRNA transcription and protein synthesis, leading to impaired metabolism and trafficking of lipids. Lipid accumulation in SRSF1-deficient hepatocytes is followed by necroptotic cell death, inflammation, and fibrosis, resulting in NASH-like liver pathology. Importantly, SRSF1-depleted human liver cancer cells recapitulate this pathogenesis, illustrating a conserved and fundamental role for SRSF1 in preserving genome integrity and tissue homeostasis. Thus, our study uncovers how the accumulation of detrimental R-loops impedes hepatocellular gene expression, triggering metabolic derangements and liver damage.

RBP-RNA interactions in the control of autoimmunity and autoinflammation

Autoimmunity and autoinflammation arise from aberrant immunological and inflammatory responses toward self-components, contributing to various autoimmune diseases and autoinflammatory diseases. RNA-binding proteins (RBPs) are essential for immune cell development and function, mainly via exerting post-transcriptional regulation of RNA metabolism and function. Functional dysregulation of RBPs and abnormities in RNA metabolism are closely associated with multiple autoimmune or autoinflammatory disorders. Distinct RBPs play critical roles in aberrant autoreactive inflammatory responses via orchestrating a complex regulatory network consisting of DNAs, RNAs and proteins within immune cells. In-depth characterizations of RBP-RNA interactomes during autoimmunity and autoinflammation will lead to a better understanding of autoimmune pathogenesis and facilitate the development of effective therapeutic strategies. In this review, we summarize and discuss the functions of RBP-RNA interactions in controlling aberrant autoimmune inflammation and their potential as biomarkers and therapeutic targets.

Splicing factor SRSF1 controls autoimmune-related molecular pathways in regulatory T cells distinct from FoxP3

Regulatory T cells (Tregs) are vital for maintaining immune self-tolerance, and their impaired function leads to autoimmune disease. Mutations in FoxP3, the master transcriptional regulator of Tregs, leads to immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome in humans and the early lethal "scurfy" phenotype with multi-organ autoimmune disease in mice. We recently identified serine/arginine-rich splicing factor 1 (SRSF1) as an indispensable regulator of Treg homeostasis and function. Intriguingly, Treg-conditional SRSF1-deficient mice exhibit early lethal systemic autoimmunity with multi-organ inflammation reminiscent of the scurfy mice. Importantly, SRSF1 is decreased in T cells from patients with the autoimmune disease systemic lupus erythematosus (SLE), and low SRSF1 levels inversely correlate with disease severity. Given that the Treg-specific deficiency of SRSF1 causes similarly profound autoimmune disease outcomes in mice as the deficiency/mutation in FoxP3, we aimed to evaluate the genes and molecular pathways controlled by these two indispensable regulatory proteins. We performed comparative bioinformatic analyses of transcriptomic profiles of Tregs from Srsf1-knockout mice and two Foxp3 mutant mice--the FoxP3-deficient ΔFoxp3 and the Foxp3 M370I mutant mice. We identified 132 differentially expressed genes (DEGs) unique to Srsf1-ko Tregs, 503 DEGs unique to Foxp3 M370I Tregs, and 1367 DEGs unique to ΔFoxp3 Tregs. Gene set enrichment and pathway analysis of DEGs unique to Srsf1-ko Tregs indicate that SRSF1 controls cytokine and immune response pathways. Conversely, FoxP3 controls pathways involved in DNA replication and cell cycle. Besides the distinct gene signatures, we identified only 30 shared genes between all three Treg mutants, mostly contributing to cytokine and immune defense pathways. Prominent genes included the chemokines CXCR6 and CCL1 and the checkpoint inhibitors FASLG and PDCD1. Thus, we demonstrate that SRSF1 and FoxP3 control common and distinct molecular pathways implicated in autoimmunity. Our analyses suggest that SRSF1 controls crucial immune functions in Tregs contributing to immune tolerance, and perturbations in its levels lead to systemic autoimmunity via mechanisms that are largely distinct from FoxP3.

Splicing factor SRSF1 is essential for CD8 T cell function and host antigen-specific viral immunity

Cytotoxic CD8 T cells are crucial for the host antigen-specific immune response to viral pathogens. Here we report the identification of an essential role for the serine/arginine-rich splicing factor (SRSF) 1 in CD8 T cell homeostasis and function. Specifically, SRSF1 is necessary for the maintenance of normal CD8 T lymphocyte numbers in the lymphoid compartment, and for the proliferative capacity and cytotoxic function of CD8 T cells. Furthermore, SRSF1 is required for antigen-specific IFN-γ cytokine responses in a viral infection challenge in mice. Transcriptomics analyses of Srsf1-deficient T cells reveal that SRSF1 controls proliferation, MAP kinase signaling and IFN signaling pathways. Mechanistically, SRSF1 controls the expression and activity of the Mnk2/p38-MAPK axis at the molecular level. Our findings reveal previously unrecognized roles for SRSF1 in the physiology and function of cytotoxic CD8 T lymphocytes and a potential molecular mechanism in viral immunopathogenesis.

Pathological mechanisms and crosstalk among different forms of cell death in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder characterized by a profound immune dysregulation and the presence of a variety of autoantibodies. Aberrant activation of programmed cell death (PCD) signaling and accelerated cell death is critical in the immunopathogenesis of SLE. Accumulating cellular components from the dead cells and ineffective clearance of the dead cell debris, in particular the nucleic acids and nucleic acids-protein complexes, provide a stable source of self-antigens, which potently activate auto-reactive B cells and promote IFN-I responses in SLE. Different cell types display distinct susceptibility and characteristics to a certain type of cell death, while different PCDs in various cells have mutual and intricate connections to promote immune dysregulation and contribute to the development of SLE. In this review, we discuss the role of various cell death pathways and their interactions in the pathogenesis of SLE. An in depth understanding of the interconnections among various forms cell death in SLE will lead to a better understanding of disease pathogenesis, shedding light on the development of novel therapeutic targets.

Serine and arginine rich splicing factor 1 deficiency alters pathways involved in IL-17A expression and is implicated in human psoriasis

Serine and Arginine Rich Splicing Factor 1 (SRSF1) is a splicing factor that binds to exonic enhancers and stimulates splicing and is previously implicated with autoimmunity. Herein, we investigate the role of SRSF1 in regulating innate immune functions that are pertinent in the pathogenesis of auto-inflammatory diseases. Specifically, we show that conditional deletion of SRSF1 in mature lymphocytes resulted in higher expression of il-17a and il-17 f and an expansion of IL17A+ CD8 T cells. Mechanistically, the aberrant expression of IL-17A in SRSF1 cKO mice could not be attributed to alternative splicing of il-17a or il-17 f genes but possibly to defective CD11B+LY6C+ myeloid derived suppressor function in the spleen. Finally, meta-analysis of RNA-Seq collected from psoriasis patients demonstrate a clear correlation between SRSF1 and psoriasis that suggests a putative role of SRSF1 in IL-17A-induced psoriasis.

The functional roles of m6A modification in T lymphocyte responses and autoimmune diseases

RNA N6-methyladenosine (m⁶A) modification is abundant in eukaryotes, bacteria and archaea. It is an RNA modification mainly existing in messenger RNA (mRNAs) and has a significant effect on the metabolism and function of mRNAs. m⁶A modification is controlled by three types of proteins, namely methyltransferase as the "writers", demethylase as the "erasers", and specific m⁶A recognized protein (YTHDF1-3) as the "readers". Recent studies have shown that m⁶A modification plays an important role in cancer, viral infection and autoimmune diseases. In this review, we will elaborate on the m⁶A modifications in the homeostasis and differentiation of T cells. Then we will further summarize the effects of m⁶A modification on the T cell responses and T cell-mediated autoimmune diseases. This will advance T cell epigenetics research and provide potential biomarkers and therapeutic targets for autoimmune diseases.

Regulation of activated T cell survival in rheumatic autoimmune diseases

Adaptive immune responses rely on the proliferation of T lymphocytes able to recognize and eliminate pathogens. The magnitude and duration of the expansion of activated T cell clones are finely regulated to minimize immunopathology and avoid autoimmunity. In patients with rheumatic autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, activated lymphocytes survive and exert effector functions for prolonged periods, defying the mechanisms that normally curb their capacities during acute and chronic infections. Here, we review the molecular mechanisms that limit the duration of immune responses in health and discuss the factors that alter such regulation in the setting of systemic lupus erythematosus and rheumatoid arthritis. We highlight defects that could contribute to the development and progression of autoimmune disease and describe how chronic inflammation can alter the regulation of activated lymphocyte survival, promoting its perpetuation. These concepts might contribute to the understanding of the mechanisms that underlie the chronicity of inflammation in the context of autoimmunity.

Splicing factor SRSF1 controls distinct molecular programs in regulatory and effector T cells implicated in systemic autoimmune disease

Systemic autoimmune diseases are characterized by hyperactive effector T cells (Teffs), aberrant cytokines and chemokines, and dysfunctional regulatory T cells (Tregs). We previously uncovered new roles for serine/arginine-rich splicing factor 1 (SRSF1) in the control of genes involved in T cell signaling and cytokine production in human T cells. SRSF1 levels are decreased in T cells from patients with systemic lupus erythematosus (SLE), and low levels correlate with severe disease. Moreover, T cell-conditional Srsf1-deficient mice recapitulate the autoimmune phenotype, exhibiting CD4 T cell hyperactivity, dysfunctional Tregs, systemic autoimmunity, and tissue inflammation. However, the role of SRSF1 in controlling molecular programs in Teffs and Tregs and how these pathways are implicated in autoimmunity is not known. Here, by comparative bioinformatics analysis, we demonstrate that SRSF1 controls largely distinct gene programs in Tregs and Teffs in vivo. SRSF1 regulates 189 differentially expressed genes (DEGs) unique to Tregs, 582 DEGs unique to Teffs, and 29 DEGs shared between both. Shared genes included IL-17A, IL-17F, CSF1, CXCL10, and CXCR4, and were highly enriched for inflammatory response and cytokine-cytokine receptor interaction pathways. SRSF1 controls distinct pathways in Tregs, which include chemokine signaling and immune cell differentiation, compared with pathways in Teffs, which include cytokine production, T cell homeostasis, and activation. We identified putative mRNA binding targets of SRSF1 which include CSF1, CXCL10, and IL-17F. Finally, comparisons with transcriptomics profiles from lupus-prone MRL/lpr mice reveal that SRSF1 controls genes and pathways implicated in autoimmune disease. The target genes of SRSF1 and putative binding targets we discovered, have known roles in systemic autoimmunity. Our findings suggest that SRSF1 controls distinct molecular pathways in Tregs and Teffs and aberrant SRSF1 levels may contribute to their dysfunction and immunopathogenesis of systemic autoimmune disease.

SRSF1 plays a critical role in invariant natural killer T cell development and function

Invariant natural killer T (iNKT) cells are highly conserved innate-like T lymphocytes that originate from CD4⁺CD8⁺ double-positive (DP) thymocytes. Here, we report that serine/arginine splicing factor 1 (SRSF1) intrinsically regulates iNKT cell development by directly targeting Myb and balancing the abundance of short and long isoforms. Conditional ablation of SRSF1 in DP cells led to a substantially diminished iNKT cell pool due to defects in proliferation, survival, and TCRα rearrangement. The transition from stage 0 to stage 1 of iNKT cells was substantially blocked, and the iNKT2 subset was notably diminished in SRSF1-deficient mice. SRSF1 deficiency resulted in aberrant expression of a series of regulators that are tightly correlated with iNKT cell development and iNKT2 differentiation, including Myb, PLZF, Gata3, ICOS, and CD5. In particular, we found that SRSF1 directly binds and regulates pre-mRNA alternative splicing of Myb and that the expression of the short isoform of Myb is substantially reduced in SRSF1-deficient DP and iNKT cells. Strikingly, ectopic expression of the Myb short isoform partially rectified the defects caused by ablation of SRSF1. Furthermore, we confirmed that the SRSF1-deficient mice exhibited resistance to acute liver injury upon α-GalCer and Con A induction. Our findings thus uncovered a previously unknown role of SRSF1 as an essential post-transcriptional regulator in iNKT cell development and functional differentiation, providing new clinical insights into iNKT-correlated disease.

Therapeutic perspectives on the metabolism of lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

INTRODUCTION

The activation of autoreactive T- and B-cells and production of autoantibodies by B cells are involved in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Recently, the concept of 'immunometabolism' has attracted significant attention. Immune cells produce large amounts of energy in the form of ATP and biosynthesize biological components such as nucleic acids and lipids via metabolic reprogramming to activate, differentiate, and exert their functions.

AREAS COVERED

While the mechanisms underlying the metabolism of CD4⁺ T cells in SLE have been extensively studied, the metabolic changes underlying B cell activation, differentiation, and function remain unclear. Drugs targeting mTOR and AMPK, such as sirolimus, rapamycin, and metformin, have shown some efficacy and tolerability in clinical trials on patients with SLE, but have not led to breakthroughs. In this review, we summarize the current knowledge on the immunometabolic mechanisms involved in SLE and RA and discuss the potential novel therapeutic drugs.

EXPERT OPINION

The intensity of activation of different immune cells and their metabolic kinetics vary in different autoimmune diseases; thus, understanding the disease- and cell-specific metabolic mechanisms may help in the development of clinically effective immunometabolism-targeting drugs.

RNA Methylation in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with complicated clinical manifestations. Although our understanding of the pathogenesis of SLE has greatly improved, the understanding of the pathogenic mechanisms of SLE is still limited by disease heterogeneity, and targeted therapy is still unavailable. Substantial evidence shows that RNA methylation plays a vital role in the mechanisms of the immune response, prompting speculation that it might also be related to the occurrence and development of SLE. RNA methylation has been a hot topic in the field of epigenetics in recent years. In addition to revealing the modification process, relevant studies have tried to explore the relationship between RNA methylation and the occurrence and development of various diseases. At present, some studies have provided evidence of a relationship between RNA methylation and SLE pathogenesis, but in-depth research and analysis are lacking. This review will start by describing the specific mechanism of RNA methylation and its relationship with the immune response to propose an association between RNA methylation and SLE pathogenesis based on existing studies and then discuss the future direction of this field.

Splicing factor SRSF1 is indispensable for regulatory T cell homeostasis and function

The ability of regulatory T (Treg) cells to control the immune response and limit the development of autoimmune diseases is determined by distinct molecular processes, which are not fully understood. We show here that serine/arginine-rich splicing factor 1 (SRSF1), which is decreased in T cells from patients with systemic lupus erythematosus, is necessary for the homeostasis and proper function of Treg cells, because its conditional absence in these cells leads to profound autoimmunity and organ inflammation by elevating the glycolytic metabolism and mTORC1 activity and the production of proinflammatory cytokines. Our data reveal a molecular mechanism that controls Treg cell plasticity and offer insights into the pathogenesis of autoimmune disease.

T Cells in Systemic Lupus Erythematosus

T-cell dysregulation has been implicated in the loss of tolerance and overactivation of B cells in systemic lupus erythematosus (SLE). Recent studies have identified T-cell subsets and genetic, epigenetic, and environmental factors that contribute to pathogenic T-cell differentiation, as well as disease pathogenesis and clinical phenotypes in SLE. Many therapeutics targeting T-cell pathways are under development, and although many have not progressed in clinical trials, the recent approval of the calcineurin inhibitor voclosporin is encouraging. Further study of T-cell subsets and biomarkers of T-cell action may pave the way for specific targeting of pathogenic T-cell populations in SLE.

Estrogen-induced hsa-miR-10b-5p is elevated in T cells from patients with systemic lupus erythematosus and downregulates splicing factor SRSF1

Objective

Autoimmune diseases affect women disproportionately more than men. Estrogen is implicated in immune cell dysfunction, yet its precise molecular roles are not fully known. We recently identified new roles for serine/arginine‐rich splicing factor 1 (SRSF1) in T cell function and autoimmunity. SRSF1 levels are decreased in T cells from patients with systemic lupus erythematosus (SLE) and are associated with active disease and comorbidity. However, the molecular mechanisms that control SRSF1 expression are unknown. Srsf1 messenger RNA (mRNA) has a long 3′‐untranslated region (3′‐UTR), suggesting posttranscriptional control. This study was undertaken to investigate the role of estrogen and posttranscriptional mechanisms of SRSF1 regulation in T cells and SLE.

Methods

In silico bioinformatics analysis of Srsf1–3′‐UTR revealed multiple microRNA (miRNA; miR)–binding sites. Additional screening and literature searches narrowed down hsa‐miR‐10b‐5p for further study. Peripheral blood T cells from healthy individuals and SLE patients were evaluated for mRNA and miRNA expression by quantitative reverse transcription–polymerase chain reaction, and SRSF1 protein levels were assessed by immunoblotting. T cells were cultured with β‐estradiol, and transient transfections were used to overexpress miRNAs. Luciferase assays were used to measure 3′‐UTR activity.

Results

We demonstrated that estrogen increased hsa‐miR‐10b‐5p expression in human T cells, and hsa‐miR‐10b‐5p down‐regulated SRSF1 protein expression. Mechanistically, hsa‐mir‐10b‐5p regulated SRSF1 posttranscriptionally via control of its 3′‐UTR activity. Importantly, hsa‐miR‐10b‐5p expression levels were elevated in T cells from healthy women compared to healthy men and also elevated in T cells from SLE patients.

Conclusion

We identified a previously unrecognized molecular link between estrogen and gene regulation in immune cells, with potential relevance to systemic autoimmune disease.

Splicing factor SRSF1 limits IFN-γ production via RhoH and ameliorates experimental nephritis

OBJECTIVE

CD4 T helper 1 (Th1) cells producing IFN-γ contribute to inflammatory responses in the pathogenesis of SLE and lupus nephritis. Moreover, elevated serum type II IFN levels precede the appearance of type I IFNs and autoantibodies in patient years before clinical diagnosis. However, the molecules and mechanisms that control this inflammatory response in SLE remain unclear. Serine/arginine-rich splicing factor 1 (SRSF1) is decreased in T cells from SLE patients, and restrains T cell hyperactivity and systemic autoimmunity. Our objective here was to evaluate the role of SRSF1 in IFN-γ production, Th1 differentiation and experimental nephritis.

METHODS

T cell-conditional Srsf1-knockout mice were used to study nephrotoxic serum-induced nephritis and evaluate IFN-γ production and Th1 differentiation by flow cytometry. RNA sequencing was used to assess transcriptomics profiles. RhoH was silenced by siRNA transfections in human T cells by electroporation. RhoH and SRSF1 protein levels were assessed by immunoblots.

RESULTS

Deletion of Srsf1 in T cells led to increased Th1 differentiation and exacerbated nephrotoxic serum nephritis. The expression levels of RhoH are decreased in Srsf1-deficient T cells, and silencing RhoH in human T cells leads to increased production of IFN-γ. Furthermore, RhoH expression was decreased and directly correlated with SRSF1 in T cells from SLE patients.

CONCLUSION

Our study uncovers a previously unrecognized role of SRSF1 in restraining IFN-γ production and Th1 differentiation through the control of RhoH. Reduced expression of SRSF1 may contribute to pathogenesis of autoimmune-related nephritis through these molecular mechanisms.

Alternative Splicing of Pre-mRNA in the Control of Immune Activity

The human immune response is a complex process that responds to numerous exogenous antigens in preventing infection by microorganisms, as well as to endogenous components in the surveillance of tumors and autoimmune diseases, and a great number of molecules are necessary to carry the functional complexity of immune activity. Alternative splicing of pre-mRNA plays an important role in immune cell development and regulation of immune activity through yielding diverse transcriptional isoforms to supplement the function of limited genes associated with the immune reaction. In addition, multiple factors have been identified as being involved in the control of alternative splicing at the cis, trans, or co-transcriptional level, and the aberrant splicing of RNA leads to the abnormal modulation of immune activity in infections, immune diseases, and tumors. In this review, we summarize the recent discoveries on the generation of immune-associated alternative splice variants, clinical disorders, and possible regulatory mechanisms. We also discuss the immune responses to the neoantigens produced by alternative splicing, and finally, we issue some alternative splicing and immunity correlated questions based on our knowledge.

Emerging roles of circular RNAs in systemic lupus erythematosus

Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed single-stranded structures lacking 5'-3' polarity and a polyadenine tail. Over recent years, a growing body of studies have been conducted to explore the roles of circRNAs in human diseases. Systemic lupus erythematosus (SLE) is a severe autoimmune disorder characterized by the presence of autoantibodies and excessive inflammation, which impact multiple organs. Recent advances have begun to shed light on the roles of circRNAs in SLE, providing fresh insights into the pathogenesis of SLE and the latent capacity for translation into clinical applications. Here, we briefly introduce these "star molecules" and summarize their roles in SLE. In addition, we outline the limitations of the current studies and raise prospects for future research.

The RNA binding protein SRSF1 is a master switch of gene expression and regulation in the immune system

Serine/Arginine splicing factor 1 (SRSF1) is an RNA binding protein abundantly expressed in most tissues. The pleiotropic functions of SRSF1 exert multiple roles in gene expression by regulating major steps in transcription, processing, export through the nuclear pores and translation of nascent RNA transcripts. The aim of this review is to highlight recent findings in the functions of this protein and to describe its role in immune system development, functions and regulation.

Immunometabolism in the pathogenesis of systemic lupus erythematosus: an update

PURPOSE OF REVIEW

To provide an update on state-of-the-art evidence on the role of immunometabolism reprogramming in the pathogenesis of systemic lupus erythematosus (SLE).

RECENT FINDINGS

Mitochondrial dysfunction and enhanced oxidative stress, along with specific defects in other metabolic pathways, can promote dysregulation of innate and adaptive immune responses in SLE. These abnormalities appear to be driven by genetic and epigenetic factors, modulated by stochastic events. In addition to extensive descriptions of abnormalities in immunometabolism of lupus lymphocytes, recent studies support the critical role of dysregulation of metabolic pathways in innate immune cells including neutrophils, macrophages and dendritic cells, in SLE pathogenesis. Recent abnormalities described in lipid metabolism have been associated with SLE disease activity and related damage. Promising therapeutic strategies that target these metabolic abnormalities have recently been described in SLE.

SUMMARY

Fundamental new insights regarding the role of mitochondrial dysfunction in innate immune dysregulation in SLE pathogenesis have recently emerged. Defects in specific molecular pathways pertinent to immunometabolism in SLE have been described. New insights in translational medicine and promising therapeutic targets have been proposed based on these recent findings.