Deficiency of T-Cell Intracellular Antigen 1 in Murine Embryonic Fibroblasts Is Associated with Changes in Mitochondrial Morphology and Respiration

T-cell intracellular antigen 1 (TIA1) is a multifunctional RNA-binding protein involved in regulating gene expression and splicing during development and in response to environmental stress, to maintain cell homeostasis and promote survival. Herein, we used TIA1-deficient murine embryonic fibroblasts (MEFs) to study their role in mitochondria homeostasis. We found that the loss of TIA1 was associated with changes in mitochondrial morphology, promoting the appearance of elongated mitochondria with heterogeneous cristae density and size. The proteomic patterns of TIA1-deficient MEFs were consistent with expression changes in molecular components related to mitochondrial dynamics/organization and respiration. Bioenergetics analysis illustrated that TIA1 deficiency enhances mitochondrial respiration. Overall, our findings shed light on the role of TIA1 in mitochondrial dynamics and highlight a point of crosstalk between potential pro-survival and pro-senescence pathways.

Expression Pattern of MicroRNA-21 during the Liver Ischemia/Reperfusion

Ischemia/reperfusion (I/R) injury in cadaveric liver transplantation is not avoidable. Liver I/R injury is an important phenomenon in hepatic damage. MicroRNA-21 (miR-21) plays an important role in I/R injury. The present study aimed to determine the expression pattern of miR-21 in liver I/R injury/recovery and its correlation with the immunologic transmission signals pathways in several days post-reperfusion. In an animal model for I/R in the liver, 40 male Balb/c mice were divided into 3 groups. The animals were monitored for 3 and 24 hours, and also for 4, 7, 14, and 28 days postreperfusion. Liver tissue damage was assessed by histopathology. The plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total antioxidant capacity (TAC) levels were measured with enzymatic assays. MiR-21, programmed cell death 4 (PDCD4) mRNA, T-cell-restricted intracellular antigen 1 (TIA1) mRNA, and fas ligand (FASL) mRNA expression levels were measured; using reverse transcription-polymerase chain reaction (RT-PCR) at different times after the reperfusion in liver tissue and blood. Histopathology and plasma ALT, AST, ALP, and TAC levels confirmed liver damage induced by I/R injury. MiR-21 increased by twofold in the liver tissue and on the inflammatory phase after 24 hours of reperfusion; it then continued to decrease up to day 7 post-reperfusion. Afterward, it continued to rise slightly up to day 14 post-reperfusion. This trend was in parallel with the recovery of the liver damage. MiR-21 expression level in the liver and blood is a predictor of the extent of I/R injury.

The Role of Antigen Processing and Presentation in Cancer and the Efficacy of Immune Checkpoint Inhibitor Immunotherapy

Recent clinical successes of cancer immunotherapy using immune checkpoint inhibitors (ICIs) are rapidly changing the landscape of cancer treatment. Regardless of initial impressive clinical results though, the therapeutic benefit of ICIs appears to be limited to a subset of patients and tumor types. Recent analyses have revealed that the potency of ICI therapies depends on the efficient presentation of tumor-specific antigens by cancer cells and professional antigen presenting cells. Here, we review current knowledge on the role of antigen presentation in cancer. We focus on intracellular antigen processing and presentation by Major Histocompatibility class I (MHCI) molecules and how it can affect cancer immune evasion. Finally, we discuss the pharmacological tractability of manipulating intracellular antigen processing as a complementary approach to enhance tumor immunogenicity and the effectiveness of ICI immunotherapy.

Precise T cell recognition programs designed by transcriptionally linking multiple receptors

Living cells often identify their correct partner or target cells by integrating information from multiple receptors, achieving levels of recognition that are difficult to obtain with individual molecular interactions. In this study, we engineered a diverse library of multireceptor cell-cell recognition circuits by using synthetic Notch receptors to transcriptionally interconnect multiple molecular recognition events. These synthetic circuits allow engineered T cells to integrate extra- and intracellular antigen recognition, are robust to heterogeneity, and achieve precise recognition by integrating up to three different antigens with positive or negative logic. A three-antigen AND gate composed of three sequentially linked receptors shows selectivity in vivo, clearing three-antigen tumors while ignoring related two-antigen tumors. Daisy-chaining multiple molecular recognition events together in synthetic circuits provides a powerful way to engineer cellular-level recognition.

General principles and escalation options of immunotherapy in autoantibody-associated disorders of the CNS

Autoimmune diseases associated with antineuronal and antiglial autoantibodies (Abs) is one of the most rapidly expanding research fields in clinical neuroimmunology, with more than 30 autoantibodies described so far. Being associated with a wide range of clinical presentations these syndromes can be diagnostically challenging. Surface or intracellular antigen localizations are crucial for the treatment response and outcome. In the latter Abs are mostly of paraneoplastic cause and tumor management should be performed as soon as possible in order to stop peripheral antigen stimulation. Immunotherapy should be started early in both groups, before irreversible neuronal loss occurs. Despite serious prognosis, aggressive therapeutic approaches can be effective in many cases. In this article we review main pathogenic mechanisms leading to Abs-related syndromes and describe standard as well as emerging strategies of immunotherapy, including tocilizumab and bortezomib. Several special therapeutic approaches will be illustrated by clinical cases recently treated in our department.

A Heterologous Cell Model for Studying the Role of T-Cell Intracellular Antigen 1 in Welander Distal Myopathy

ABSTRACT Welander distal myopathy (WDM) is a muscle dystrophy characterized by adult-onset distal muscle weakness, prevalently impacting the distal long extensors of the hands and feet. WDM is an autosomal dominant disorder caused by a missense mutation (c.1362G>A; p.E384K) in the TIA1 (T-cell intracellular antigen 1) gene, which encodes an RNA-binding protein basically required for the posttranscriptional regulation of RNAs. We have developed a heterologous cell model of WDM to study the molecular and cellular events associated with mutated TIA1 expression. Specifically, we analyzed how this mutation affects three regulatory functions mediated by TIA1: (i) control of alternative SMN2 (survival motor neuron 2) splicing; (ii) formation, assembly, and disassembly of stress granules; and (iii) mitochondrial dynamics and its consequences for mitophagy, autophagy, and apoptosis. Our results show that whereas WDM-associated TIA1 expression had only a mild effect on SMN2 splicing, it led to suboptimal adaptation to environmental stress, with exacerbated stress granule formation that was accompanied by mitochondrial dysfunction and autophagy. Overall, our observations indicate that some aspects of the cell phenotype seen in muscle of patients with WDM can be recapitulated by ectopic expression of WDM-TIA1 in embryonic kidney cells, highlighting the potential of this model to investigate the pathogenesis of this degenerative disease and possible therapeutics.