Defining the landscape of TIA1 and SQSTM1 digenic myopathy.

TIA1/SQSTM1 myopathy is one of the few digenic myopathies. We describe four new French adult male patients carrying the TIA1 p.Asn357Ser and SQSTM1 p.Pro392Leu variant and review the literature to include 20 additional cases to define the spectrum of the disease. These twenty-four patients (75% males) had late-onset (52,6 ± 10,1 years), mainly asymmetric, distal ankle and hand finger extension weakness (75%), mild CK elevation (82.4%) and myopathic EMG. Two of the four French patients had sensorimotor axonal polyneuropathy and an additional one had neurogenic changes in muscle biopsy. Muscle biopsy showed rimmed vacuoles (44.4%), myofibrillar disorganization (16.7%) or both (38.9%), with P62/TDP43 aggregates. The TIA1 p.Asn357Ser variant was present in all patients and the SQSTM1 p.Pro392Leu was the most frequent (71%) of the four reported SQSTM1 variants. We reviewed the distal myopathy gene panels of Pitié-Salpêtrière's hospital cohort finding a prevalence of 11/414=2.7% of the TIA1 p.Asn357Ser variant, with two patients having an alternative diagnosis (TTN and MYH7) with atypical phenotypes, resembling some of the features seen in TIA1/SQSTM1 myopathy. Overall, TIA1/SQSTM1 myopathy has a homogenous phenotype reinforcing the pathogenicity of its digenic variants. We confirm an increased burden of the TIA1 p.Asn357Ser variant in distal myopathy patients which could act as a genetic modifier.

Diverse Phenotypic Presentation of the Welander Distal Myopathy Founder Mutation, With Myopathy and Amyotrophic Lateral Sclerosis in the Same Family.

ABSTRACT: Welander distal myopathy is a rare myopathy with prominent and early involvement of distal upper extremity muscles, prevalent in individuals of Scandinavian origin, and caused by a founder mutation in the cytotoxic granule-associated RNA-binding protein (T-cell intracellular antigen-1; TIA1), E384K. Different pathogenic variants in the TIA1 gene, distinct from the founder 1, have recently been associated with frontotemporal dementia and amyotrophic lateral sclerosis (ALS), suggesting that TIA1-related disorders belong to the group of multisystem proteinopathies. We describe the first case of a two-generation family with the founder E384K TIA1 mutation demonstrating phenotypic variability; the mother manifested as Welander myopathy, whereas 2 daughters manifested as ALS. No other genetic cause of ALS was found in 1 of the affected daughters. We also discuss the possible mechanisms explaining this pleotropic presentation of the founder mutation.

Chandipura Virus Forms Cytoplasmic Inclusion Bodies through Phase Separation and Proviral Association of Cellular Protein Kinase R and Stress Granule Protein TIA-1.

Negative-strand RNA viruses form cytoplasmic inclusion bodies (IBs) representing virus replication foci through phase separation or biomolecular condensation of viral and cellular proteins, as a hallmark of their infection. Alternatively, mammalian cells form stalled mRNA containing antiviral stress granules (SGs), as a consequence of phosphorylation of eukaryotic initiation factor 2α (eIF2α) through condensation of several RNA-binding proteins including TIA-1. Whether and how Chandipura virus (CHPV), an emerging human pathogen causing influenza-like illness, coma and death, forms IBs and evades antiviral SGs remain unknown. By confocal imaging on CHPV-infected Vero-E6 cells, we found that CHPV infection does not induce formation of distinct canonical SGs. Instead, CHPV proteins condense and co-localize together with SG proteins to form heterogeneous IBs, which ensued independent of the activation of eIF2α and eIF2α kinase, protein kinase R (PKR). Interestingly, siRNA-mediated depletion of PKR or TIA-1 significantly decreased viral transcription and virion production. Moreover, CHPV infection also caused condensation and recruitment of PKR to IBs. Compared to SGs, IBs exhibited significant rapidity in disassembly dynamics. Altogether, our study demonstrating that CHPV replication co-optimizes with SG proteins and revealing an unprecedented proviral role of TIA-1/PKR may have implications in understanding the mechanisms regulating CHPV-IB formation and designing antiviral therapeutics. Importance: CHPV is an emerging tropical pathogen reported to cause acute influenza-like illness and encephalitis in children with a very high mortality rate of ~70%. Lack of vaccines and an effective therapy against CHPV makes it a potent pathogen for causing an epidemic in tropical parts of globe. Given these forewarnings, it is of paramount importance that CHPV biology must be understood comprehensively. Targeting of host factors offers several advantages over targeting the viral components due to the generally higher mutation rate in the viral genome. In this study, we aimed at understanding the role of SGs forming cellular RNA-binding proteins in CHPV replication. Our study helps understand participation of cellular factors in CHPV replication and could help develop effective therapeutics against the virus.

The miR-30-5p/TIA-1 axis directs cellular senescence by regulating mitochondrial dynamics.

Senescent cells exhibit a diverse spectrum of changes in their morphology, proliferative capacity, senescence-associated secretory phenotype (SASP) production, and mitochondrial homeostasis. These cells often manifest with elongated mitochondria, a hallmark of cellular senescence. However, the precise regulatory mechanisms orchestrating this phenomenon remain predominantly unexplored. In this study, we provide compelling evidence for decreases in TIA-1, a pivotal regulator of mitochondrial dynamics, in models of both replicative senescence and ionizing radiation (IR)-induced senescence. The downregulation of TIA-1 was determined to trigger mitochondrial elongation and enhance the expression of senescence-associated ß-galactosidase, a marker of cellular senescence, in human foreskin fibroblast HS27 cells and human keratinocyte HaCaT cells. Conversely, the overexpression of TIA-1 mitigated IR-induced cellular senescence. Notably, we identified the miR-30-5p family as a novel factor regulating TIA-1 expression. Augmented expression of the miR-30-5p family was responsible for driving mitochondrial elongation and promoting cellular senescence in response to IR. Taken together, our findings underscore the significance of the miR-30-5p/TIA-1 axis in governing mitochondrial dynamics and cellular senescence.

Deciphering the role of Zn2+-binding histidines from TIA-1 on the assembly and dynamics of stress granules.

T-cell intracellular antigen-1 (TIA-1) is a key RNA-binding protein that participates in translation regulation and RNA splicing. TIA-1 undergoes liquid-liquid phase separation as a fundamental mechanism that enables the condensation of RNA and proteins into membraneless organelles called stress granules (SGs). However, this dynamic behavior can lead to aberrant fibril formation, implicated in neurodegenerative disorders, and must be tightly regulated. In this study, we investigated the role in the cell of histidine residues His94 and His96, responsible for Zn2+ binding. Using fluorescence microscopy, we found that the specific binding site formed by these residues is critical for SG assembly. Furthermore, it also plays a role maintaining the dynamic behavior of SG-assembled TIA-1. Collectively, our findings confirm the physiological relevance of TIA-1 His94 and His96 in the Zn2+-mediated regulatory mechanism for protection against fibril formation in SGs.

Distal myopathy due to digenic inheritance of TIA1 and SQSTM1 variants in two unrelated Spanish patients.

Welander distal myopathy typically manifests in late adulthood and is caused by the founder TIA1 c.1150G>A (p.Glu384Lys) variant in families of Swedish and Finnish descent. Recently, a similar phenotype has been attributed to the digenic inheritance of TIA1 c.1070A>G (p.Asn357Ser) and SQSTM1 c.1175C>T (p.Pro392Leu) variants. We describe two unrelated Spanish patients presenting with slowly progressive gait disturbance, distal-predominant weakness, and mildly elevated creatine kinase (CK) levels since their 6th decade. Electromyography revealed abnormal spontaneous activity and a myopathic pattern. Muscle magnetic resonance imaging (MRI) showed marked fatty replacement in distal leg muscles. A muscle biopsy, performed on one patient, revealed myopathic changes with rimmed vacuoles. Both patients carried the TIA1 p.Asn357Ser and SQSTM1 p.Pro392Leu variants. Digenic inheritance is supported by evidence from unrelated pedigrees and a plausible biological interaction between both proteins in protein quality control processes. Recent functional studies and additional case descriptions further support this. Clinical suspicion is necessary to seek both variants.

Mutagenesis and structural studies reveal the basis for the specific binding of SARS-CoV-2 SL3 RNA element with human TIA1 protein.

Viral RNA-host protein interactions are indispensable during RNA virus transcription and replication, but their detailed structural and dynamical features remain largely elusive. Here, we characterize the binding interface for the SARS-CoV-2 stem-loop 3 (SL3) cis-acting element to human TIA1 protein with a combined theoretical and experimental approaches. The highly structured SARS-CoV-2 SL3 has a high binding affinity to TIA1 protein, in which the aromatic stacking, hydrogen bonds, and hydrophobic interactions collectively direct this specific binding. Further mutagenesis studies validate our proposed 3D binding model and reveal two SL3 variants have enhanced binding affinities to TIA1. And disruptions of the identified RNA-protein interactions with designed antisense oligonucleotides dramatically reduce SARS-CoV-2 infection in cells. Finally, TIA1 protein could interact with conserved SL3 RNA elements within other betacoronavirus lineages. These findings open an avenue to explore the viral RNA-host protein interactions and provide a pioneering structural basis for RNA-targeting antiviral drug design.

Liquid Droplet Aging and Seeded Fibril Formation of the Cytotoxic Granule Associated RNA Binding Protein TIA1 Low Complexity Domain.

Protein domains biased toward a few amino acid types are vital for the formation of biomolecular condensates in living cells. These membraneless compartments are formed by molecules exhibiting a range of molecular motions and structural order. Missense mutations increase condensate persistence lifetimes or structural order, properties that are thought to underlie pathological protein aggregation. In the context of stress granules associated with neurodegenerative diseases, this process involves the rigidification of protein liquid droplets into ß-strand rich protein fibrils. Here, we characterize the molecular mechanism underlying the rigidification of liquid droplets for the low complexity domain of the Cytotoxic granule associated RNA binding protein TIA1 (TIA1) stress granule protein and the influence of a disease mutation linked to neurodegenerative diseases. A seeding procedure and solid state nuclear magnetic resonance measurements show that the low complexity domain converges on a ß-strand rich fibril conformation composed of 21% of the sequence. Additional solid state nuclear magnetic resonance measurements and difference spectroscopy show that aged liquid droplets of wild type and a proline-to-leucine mutant low complexity domain are composed of fibril assemblies that are conformationally heterogeneous and structurally distinct from the seeded fibril preparation. Regarding low complexity domains, our data support the functional template-driven formation of conformationally homogeneous structures, that rigidification of liquid droplets into conformationally heterogenous structures promotes pathological interactions, and that the effect of disease mutations is more nuanced than increasing thermodynamic stability or increasing ß-strand structure content.

A guide to selecting high-performing antibodies for RNA-binding protein TIA1 for use in Western Blot, immunoprecipitation and immunofluorescence.

A member of the RNA-binding protein family, T-cell intracellular antigen-1 (TIA1) regulates mRNA translation and splicing as well as cellular stress by promoting stress granule formation. Variants of the TIA1 gene have implications in neurogenerative disorders including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Reproducible research on TIA1 would be enhanced with the availability of high-quality anti-TIA1 antibodies. In this study, we characterized twelve TIA1 commercial antibodies for Western Blot, immunoprecipitation, and immunofluorescence using a standardized experimental protocol based on comparing read-outs in knockout cell lines and isogenic parental controls. We identified many high-performing antibodies and encourage readers to use this report as a guide to select the most appropriate antibody for their specific needs.

RAMP2-AS1 stabilized RAPM2 mRNA through TIA1 to inhibit the progression of non-small cell lung cancer.

As the most common subtype of lung cancer, non-small cell lung cancer (NSCLC)is responsible for a large proportion of global cancer-caused deaths. The implication of long non-coding RNAs (lncRNAs) as tumor-suppressor or carcinogenic genes in NSCLC has been widely documented. Our study sought to investigate the performance of lncRNA RAMP2 antisense RNA1 (RAMP2-AS1) in NSCLC. GEPIA bioinformatics tool and RT-qPCR were applied for assessing the expression of RAMP2-AS1 and its neighboring gene receptor activity-modifying protein 2 (RAMP2) in NSCLC. Functional assays including CCK-8 assay, colony formation assay as well as caspase-3 activity analysis and Transwell invasion assays were applied for detecting the biological phenotypes of NSCLC cells. Interaction among RAMP2-AS1, RAMP2 and T-cell intracellular antigen 1cytotoxic granule associated RNA binding protein (TIA1) was evaluated by RNA immunoprecipitation and pulldown assays. We found that RAMP2-AS1 and RAMP2 were downregulated in NSCLC. Overexpression of RAMP2-AS1 hampered proliferation and invasion, whereas induced apoptosis of NSCLC cells. Mechanistically, RAMP2-AS1 interacted with TIA1 to stabilize the mRNA of RAMP2. In conclusion, we first uncovered that RAMP2-AS1 stabilized RAPM2 mRNA through TIA1 to inhibit the progression of NSCLC, providing new insight to improve the treatment efficacy of NSCLC.

The splicing regulators TIA1 and TIAL1 are required for the expression of the DNA damage repair machinery during B cell lymphopoiesis.

B cell lymphopoiesis requires dynamic modulation of the B cell transcriptome for timely coordination of somatic mutagenesis and DNA repair in progenitor B (pro-B) cells. Here, we show that, in pro-B cells, the RNA-binding proteins T cell intracellular antigen 1 (TIA1) and TIA1-like protein (TIAL1) act redundantly to enable developmental progression. They are global splicing regulators that control the expression of hundreds of mRNAs, including those involved in DNA damage repair. Mechanistically, TIA1 and TIAL1 bind to 5' splice sites for exon definition, splicing, and expression of DNA damage sensors, such as Chek2 and Rif1. In their absence, pro-B cells show exacerbated DNA damage, altered P53 expression, and increased cell death. Our study uncovers the importance of tight regulation of RNA splicing by TIA1 and TIAL1 for the expression of integrative transcriptional programs that control DNA damage sensing and repair during B cell development.

ALS mutations in the TIA-1 prion-like domain trigger highly condensed pathogenic structures.

T cell intracellular antigen-1 (TIA-1) plays a central role in stress granule (SG) formation by self-assembly via the prion-like domain (PLD). In the TIA-1 PLD, amino acid mutations associated with neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) or Welander distal myopathy (WDM), have been identified. However, how these mutations affect PLD self-assembly properties has remained elusive. In this study, we uncovered the implicit pathogenic structures caused by the mutations. NMR analysis indicated that the dynamic structures of the PLD are synergistically determined by the physicochemical properties of amino acids in units of five residues. Molecular dynamics simulations and three-dimensional electron crystallography, together with biochemical assays, revealed that the WDM mutation E384K attenuated the sticky properties, whereas the ALS mutations P362L and A381T enhanced the self-assembly by inducing ß-sheet interactions and highly condensed assembly, respectively. These results suggest that the P362L and A381T mutations increase the likelihood of irreversible amyloid fibrillization after phase-separated droplet formation, and this process may lead to pathogenicity.

T-Cell Intracellular Antigen 1-Like Protein in Physiology and Pathology.

T-cell intracellular antigen 1 (TIA1)-related/like (TIAR/TIAL1) protein is a multifunctional RNA-binding protein (RBP) involved in regulating many aspects of gene expression, independently or in combination with its paralog TIA1. TIAR was first described in 1992 by Paul Anderson's lab in relation to the development of a cell death phenotype in immune system cells, as it possesses nucleolytic activity against cytotoxic lymphocyte target cells. Similar to TIA1, it is characterized by a subcellular nucleo-cytoplasmic localization and ubiquitous expression in the cells of different tissues of higher organisms. In this paper, we review the relevant structural and functional information available about TIAR from a triple perspective (molecular, cellular and pathophysiological), paying special attention to its expression and regulation in cellular events and processes linked to human pathophysiology.

Successful early diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma manifesting as chronic diarrhea and hypokalemia using video capsule endoscopy and double-balloon enteroscopy.

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), formerly known as enteropathy-associated T-cell lymphoma (EATL) type II, is a rare disease with a poor prognosis that is often diagnosed when patients present with intestinal perforation or obstruction. Our patient, a man in his 60 s, had a 5-month history of persistent watery diarrhea. Upper and lower gastrointestinal endoscopy, abdominal computed tomography (CT), and stool culture results were unremarkable. He was admitted to our hospital 8 months later with a weight loss of 20 kg, general fatigue, and hypokalemia. Contrast-enhanced CT of the abdomen revealed mild thickening and contrast enhancement of the small intestinal wall. Video capsule endoscopy and double-balloon enteroscopy were performed to reveal a broad ulcer in the jejunum and multiple erosions throughout the small intestine. Examination of the biopsy specimens showed infiltration of atypical lymphocytes with pale cytoplasm in the glandular epithelium. The atypical lymphocytes were positive for CD3, CD8, CD56, granzyme B, and T-cell intracellular antigen-1 by immunostaining. Early diagnosis of MEITL was made, and the patient survived for 21 months with continuous chemotherapy. Aggressive examination of the small intestine is effective for the early diagnosis of serious diseases, such as MEITL, in patients with chronic diarrhea of unknown origin.

Intracellular accumulation of tau inhibits autophagosome formation by activating TIA1-amino acid-mTORC1 signaling.

BACKGROUND: Autophagy dysfunction plays a crucial role in tau accumulation and neurodegeneration in Alzheimer's disease (AD). This study aimed to investigate whether and how the accumulating tau may in turn affect autophagy. METHODS: The primary hippocampal neurons, N2a and HEK293T cells with tau overexpression were respectively starved and treated with vinblastine to study the effects of tau on the initiating steps of autophagy, which was analysed by Student's two-tailed t-test. The rapamycin and concanamycin A were employed to inhibit the mammalian target of rapamycin kinase complex 1 (mTORC1) activity and the vacuolar H+-ATPase (v-ATPase) activity, respectively, which were analysed by One-way ANOVA with post hoc tests. The Western blotting, co-immunoprecipitation and immunofluorescence staining were conducted to gain insight into the mechanisms underlying the tau effects of mTORC1 signaling alterations, as analysed by Student's two-tailed t-test or One-way ANOVA with post hoc tests. The autophagosome formation was detected by immunofluorescence staining and transmission electron microscopy. The amino acids (AA) levels were detected by high performance liquid chromatography (HPLC). RESULTS: We observed that overexpressing human full-length wild-type tau to mimic AD-like tau accumulation induced autophagy deficits. Further studies revealed that the increased tau could bind to the prion-related domain of T cell intracellular antigen 1 (PRD-TIA1) and this association significantly increased the intercellular level of amino acids (Leucine, P = 0.0038; Glutamic acid, P = 0.0348; Alanine, P = 0.0037; Glycine, P = 0.0104), with concordant upregulation of mTORC1 activity [phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (p-4EBP1), P < 0.0001; phosphorylated 70 kDa ribosomal protein S6 kinase 1 (p-p70S6K1), P = 0.0001, phosphorylated unc-51-like autophagy-activating kinase 1 (p-ULK1), P = 0.0015] and inhibition of autophagosome formation [microtubule-associated protein light chain 3 II (LC3 II), P = 0.0073; LC3 puncta, P < 0.0001]. As expected, this tau-induced deficit of autophagosome formation in turn aggravated tau accumulation. Importantly, we also found that blocking TIA1 and tau interaction by overexpressing PRD-TIA1, downregulating the endogenous TIA1 expression by shRNA, or downregulating tau protein level by a small proteolysis targeting chimera (PROTAC) could remarkably attenuate tau-induced autophagy impairment. CONCLUSIONS: Our findings reveal that AD-like tau accumulation inhibits autophagosome formation and induces autophagy deficits by activating the TIA1/amino acid/mTORC1 pathway, and thus this work reveals new insight into tau-associated neurodegeneration and provides evidence supporting the use of new therapeutic targets for AD treatment and that of related tauopathies.

The role of peritumoral CD8 + /TIA1 + lymphocytes in hepatocellular carcinoma aggressiveness and recurrence after surgical resection.

Hepatocellular carcinoma (HCC) is characterized by a low mutation burden and a relatively low number of tumor-infiltrating lymphocytes (TILs), making still difficult to identify targets for specific therapies. The aim of this study was the identification of the prognostic role of TILs in HCC, focusing on their distribution and status of activation. We retrospectively enrolled 41 patients, undergone to liver resection for HCC. A significant increase of CD8 + intratumoral lymphocytes was observed in HCCs with prevalent solid architecture, but with a higher PD-1/TIA1 ratio, suggesting that HCCs with solid architecture have more peri-tumoral lymphocytes, but with minor functionality. At multivariate and univariate analyses, TIA1/CD8 ratio correlated with tumor recurrence, meaning that HCC with more activated TILs are characterized by a higher tumor aggressiveness. The use of a feasible and cheap immunohistochemical panel can help in post-surgical prognostic stratification, focusing not only in the raw number and density of TILs, but more on their state of activation and morphology.

Key Modulators of the Stress Granule Response TIA1, TDP-43, and G3BP1 Are Altered by Polyglutamine-Expanded ATXN7.

Spinocerebellar ataxia type 7 (SCA7) and other polyglutamine (polyQ) diseases are caused by expansions of polyQ repeats in disease-specific proteins. Aggregation of the polyQ proteins resulting in various forms of cellular stress, that could induce the stress granule (SG) response, is believed to be a common pathological mechanism in these disorders. SGs can contribute to cell survival but have also been suggested to exacerbate disease pathology by seeding protein aggregation. In this study, we show that two SG-related proteins, TDP-43 and TIA1, are sequestered into the aggregates formed by polyQ-expanded ATXN7 in SCA7 cells. Interestingly, mutant ATXN7 also localises to induced SGs, and this association altered the shape of the SGs. In spite of this, neither the ability to induce nor to disassemble SGs, in response to arsenite stress induction or relief, was affected in SCA7 cells. Moreover, we could not observe any change in the number of ATXN7 aggregates per cell following SG induction, although a small, non-significant, increase in total aggregated ATXN7 material could be detected using filter trap. However, mutant ATXN7 expression in itself increased the speckling of the SG-nucleating protein G3BP1 and the SG response. Taken together, our results indicate that the SG response is induced, and although some key modulators of SGs show altered behaviour, the dynamics of SGs appear normal in the presence of mutant ATXN7.

CRNDE inducing cisplatin resistance through SRSF1/TIA1 signaling pathway in ovarian cancer.

BACKGROUND: CRNDE is known to be an important predictive factor of prognosis in many tumors; however, its role in cisplatin resistance is still unknown in ovarian cancer. The aim of the current research was to investigate the association between CRNDE and cisplatin resistance. MATERIALS AND METHODS: QRT-PCR and in situ hybridization assay were employed to detect the expression of CRNDE in ovarian cancer cells and tissues; CCK8 assay, AnnexinV-FITC apoptosis assay and Trans-well assay, to determine the cell proliferation, apoptosis and invasion; and RNA-pull down assay, mass spectrometry analysis, gene microarray to search the targeted gene of CRNDE and SRSF1. Association of CRNDE with SRSF1 was determined in ovarian cancer cells and nude mice. RESULTS: It was found that CRNDE and SRSF1 expression were higher in the cisplatin resistant ovarian cancer cells than their control cells. High expression of CRNDE and SRSF1 led to cisplatin resistance. While inhibition of CRNDE or SRSF1 sensitized ovarian cancer to cisplatin in vitro and in vivo. Moreover, as indicated in RIP assay, SRSF1 was potentially the targeted gene of CRNDE, and CRNDE promoting SRSF1 expression to induce cisplatin resistance; as indicated in gene microassay, there was significantly positive correlation between SRSF1 and TIA1, and SRSF1 promoting TIA1 expression. CONCLUSION: In conclusion, CRNDE induced cisplatin resistance in ovarian cancer through SRSF1/TIA1 signaling pathway; thus, CRNDE inhibitor or SRSF1 inhibitor combined with cisplatin might act as a novel promising approach to ovarian cancer.

Dynamics of T-Cell Intracellular Antigen 1-Dependent Stress Granules in Proteostasis and Welander Distal Myopathy under Oxidative Stress.

T-cell intracellular antigen 1 (TIA1) is an RNA-binding protein that is primarily involved in the post-transcriptional regulation of cellular RNAs. Furthermore, it is a key component of stress granules (SGs), RNA, and protein aggregates that are formed in response to stressful stimuli to reduce cellular activity as a survival mechanism. TIA1 p.E384K mutation is the genetic cause of Welander distal myopathy (WDM), a late-onset muscular dystrophy whose pathogenesis has been related to modifying SG dynamics. In this study, we present the results obtained by analyzing two specific aspects: (i) SGs properties and dynamics depending on the amino acid at position 384 of TIA1; and (ii) the formation/disassembly time-course of TIA1WT/WDM-dependent SGs under oxidative stress. The generation of TIA1 variants-in which the amino acid mutated in WDM and the adjacent ones were replaced by lysines, glutamic acids, or alanines-allowed us to verify that the inclusion of a single lysine is necessary and sufficient to alter SGs dynamics. Moreover, time-lapse microscopy analysis allowed us to establish in vivo the dynamics of TIA1WT/WDM-dependent SG formation and disassembly, after the elimination of the oxidizing agent, for 1 and 3 h, respectively. Our observations show distinct dynamics between the formation and disassembly of TIA1WT/WDM-dependent SGs. Taken together, this study has allowed us to expand the existing knowledge on the role of TIA1 and the WDM mutation in SG formation.

The Multifunctional Faces of T-Cell Intracellular Antigen 1 in Health and Disease.

T-cell intracellular antigen 1 (TIA1) is an RNA-binding protein that is expressed in many tissues and in the vast majority of species, although it was first discovered as a component of human cytotoxic T lymphocytes. TIA1 has a dual localization in the nucleus and cytoplasm, where it plays an important role as a regulator of gene-expression flux. As a multifunctional master modulator, TIA1 controls biological processes relevant to the physiological functioning of the organism and the development and/or progression of several human pathologies. This review summarizes our current knowledge of the molecular aspects and cellular processes involving TIA1, with relevance for human pathophysiology.