Translational initiation regulated by ATM in dendritic cells development

Identification and validation of biomarkers related to ferroptosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a kind of interstitial lung disease (ILD). It has a high incidence rate and mortality. Its pathogenesis remains unclear. So far, no effective methods have been found for the early diagnosis of IPF. Ferroptosis has been reported to be critical in the initiation and progression of IPF. Therefore, our aim was to identify the hub gene related to ferroptosis co-expressed in the peripheral blood and pulmonary tissue of patients with IPF. Sequencing data were obtained from the Gene Expression Omnibus database. A comprehensive analysis was conducted on the differentially expressed genes (DEGs) to extract ferroptosis-related differentially expressed genes (FRDEGs). The results showed that ferroptosis-related signal paths were highly enriched in IPF, and 10 FRDEGs were identified.The hub gene was predicted through protein-protein interactions (PPI) and Cytoscape. The diagnostic utility of the hub gene was proven by enzyme-linked immunosorbent assay (ELISA) in serum and by immunohistochemistry (IHC) in pulmonary tissues. The results of ELISA indicated that the levels of ATM in the serum of patients with IPF were significantly lower than the normal levels. In contrast, the results of IHC showed that the expression of ATM in the pulmonary tissues of IPF patients exhibited a notably elevated trend. The immune status was assessed by the CIBERSORT method and so was the relevance between ATM and immune cells. These findings unveiled significant differences in various immune cell types in peripheral blood and pulmonary tissue between the IPF group and the control group. Furthermore, ATM was associated with various immune cells. This study suggests that as a ferroptosis-related gene, ATM assumes a pivotal role in the diagnosis and treatment of IPF. This discovery presents a novel approach for the clinical diagnosis and therapy of IPF.

ATM in immunobiology: From lymphocyte development to cancer immunotherapy

Ataxia Telangiectasia Mutated (ATM) is a protein kinase traditionally known for its role in DNA damage response and cell cycle regulation. However, emerging research has revealed its multifaceted and crucial functions in the immune system. This comprehensive review explores the diverse roles of ATM in immune regulation, from lymphocyte development to its involvement in cancer immunotherapy. The review describes ATM's critical functions in V(D)J recombination and class switch recombination, highlighting its importance in adaptive immunity. It examines ATM's role in innate immunity, particularly in NF-κB signaling and cytokine production. Furthermore, the review analyzes the impact of ATM deficiency on oxidative stress and mitochondrial function in immune cells, providing insights into the immunological defects observed in Ataxia Telangiectasia (A-T). The article explores ATM's significance in maintaining hematopoietic stem cell function and its implications for bone marrow transplantation and gene therapy. Additionally, it addresses ATM's involvement in inflammation and immune senescence, linking DNA damage response to age-related immune decline. Finally, this review highlights the emerging role of ATM in cancer immunotherapy, where its inhibition shows promise in enhancing immune checkpoint blockade therapy. This review synthesizes current knowledge on ATM's functions in the immune system, offering insights into the pathophysiology of ATM-related disorders and potential therapeutic strategies for immune-related conditions and cancer immunotherapy.

GM-CSF Protects Macrophages from DNA Damage by Inducing Differentiation

At inflammatory loci, pro-inflammatory activation of macrophages produces large amounts of reactive oxygen species (ROS) that induce DNA breaks and apoptosis. Given that M-CSF and GM-CSF induce two different pathways in macrophages, one for proliferation and the other for survival, in this study we wanted to determine if these growth factors are able to protect against the DNA damage produced during macrophage activation. In macrophages treated with DNA-damaging agents we found that GM-CSF protects better against DNA damage than M-CSF. Treatment with GM-CSF resulted in faster recovery of DNA damage than treatment with M-CSF. The number of apoptotic cells induced after DNA damage was higher in the presence of M-CSF. Protection against DNA damage by GM-CSF is not related to its higher capacity to induce proliferation. GM-CSF induces differentiation markers such as CD11c and MHCII, as well as the pro-survival Bcl-2A1 protein, which make macrophages more resistant to DNA damage.

DNA Damage Response in the Adaptive Arm of the Immune System: Implications for Autoimmunity

In complex environments, cells have developed molecular responses to confront threats against the genome and achieve the maintenance of genomic stability assuring the transfer of undamaged DNA to their progeny. DNA damage response (DDR) mechanisms may be activated upon genotoxic or environmental agents, such as cytotoxic drugs or ultraviolet (UV) light, and during physiological processes requiring DNA transactions, to restore DNA alterations that may cause cellular malfunction and affect viability. In addition to the DDR, multicellular organisms have evolved specialized immune cells to respond and defend against infections. Both adaptive and innate immune cells are subjected to DDR processes, either as a prerequisite to the immune response, or as a result of random endogenous and exogenous insults. Aberrant DDR activities have been extensively studied in the immune cells of the innate arm, but not in adaptive immune cells. Here, we discuss how the aberrant DDR may lead to autoimmunity, with emphasis on the adaptive immune cells and the potential of therapeutic targeting.

Loss of lipid phosphatase SHIP1 promotes macrophage differentiation through suppression of dendritic cell differentiation

SH2-containing inositol 5'-phosphatase-1 (SHIP1) deficiency in mice results in abnormal myeloid expansion, and proinflammatory conditions in the lung. However, the mechanisms involved in SHIP1-mediated regulation of myeloid differentiation remain unclear. Here we show that SHIP1 is a key regulator of early differentiation for dendritic cells (DCs). We also provide critical evidence to modify the function of SHIP1 in in vitro development of BMDCs using the recent framework of defining DCs. We found that loss of SHIP1 suppresses GM-CSF-induced formation of bone marrow-derived DC (BMDC) colonies, leading to reduced BMDC number in BM cell culture. The number of maturated BMDCs decreased in SHIP1-KO culture, due to reduction of immature BMDCs, suggesting SHIP1 is critical for lineage commitment rather than for maturation from myeloid precursors to DCs. We further showed that F4/80⁺/MHCII^low BM macrophage-like cells (BMMs) were the main population of SHIP1-KO BM culture. Treatment of wild-type BM culture with 3 α-aminocholestane (3AC), a specific inhibitor for functional activity of SHIP1, caused a similar developmental defect in BMDCs as seen in SHIP1-KO cells, resulting in the absence of BMDC colony, and increased number of BMMs in BM culture. In conclusion, our results suggest that differentiation of BMDCs are markedly impaired under SHIP1 deficient condition, which causes skewed development of myeloid lineage cells manifested as pathological conditions associated with an excess of macrophage population.

The screening of a microRNA expression during development of human macrophages and mouse dendritic cells

There is increasing evidence showing specific roles of microRNA in cell differentiation and cancer progression. Here we examine miRNA profiles during maturation of monocytes and bone marrow-derived dendritic cells (BMDCs) in human and mouse, respectively. We have identified significant changes of various miRNA expression during monocyte and BMDC monocyte development via miRNA microarrays, confirmed by quantitative PCR. Increases in miR155 expression positively correlated with increasing maturity of monocyte and BMDC in both mouse and human microarrays, indicating its importance in development. We describe a requirement of miR155 for MHCII expression during GM-CSF-induced development and LPS-induced maturation of DCs, suggesting reduced immune function of DC when miR155 is absent. Our study suggests that miRNAs might have an important role in differentiation of myeloid cell such as dendritic cells and macrophages.

NOX2-dependent ATM kinase activation dictates pro-inflammatory macrophage phenotype and improves effectiveness to radiation therapy

Although tumor-associated macrophages have been extensively studied in the control of response to radiotherapy, the molecular mechanisms involved in the ionizing radiation-mediated activation of macrophages remain elusive. Here we show that ionizing radiation induces the expression of interferon regulatory factor 5 (IRF5) promoting thus macrophage activation toward a pro-inflammatory phenotype. We reveal that the activation of the ataxia telangiectasia mutated (ATM) kinase is required for ionizing radiation-elicited macrophage activation, but also for macrophage reprogramming after treatments with γ-interferon, lipopolysaccharide or chemotherapeutic agent (such as cisplatin), underscoring the fact that the kinase ATM plays a central role during macrophage phenotypic switching toward a pro-inflammatory phenotype through the regulation of mRNA level and post-translational modifications of IRF5. We further demonstrate that NADPH oxidase 2 (NOX2)-dependent ROS production is upstream to ATM activation and is essential during this process. We also report that the inhibition of any component of this signaling pathway (NOX2, ROS and ATM) impairs pro-inflammatory activation of macrophages and predicts a poor tumor response to preoperative radiotherapy in locally advanced rectal cancer. Altogether, our results identify a novel signaling pathway involved in macrophage activation that may enhance the effectiveness of radiotherapy through the reprogramming of tumor-infiltrating macrophages.

Cell Differentiation and Checkpoint

DNA damage is induced in many types of cells by internal and external cell stress. When DNA is damaged, DNA Damage Response (DDR) programs are activated to repair the DNA lesions in order to preserve genomic integrity and suppress subsequent malignant transformation. Among these programs is cell cycle checkpoint that ensures cell cycle arrest and subsequent repair of the damaged DNA, apoptosis and senescence in various phases of the cell cycle. Moreover, recent studies have established the cell differentiation checkpoint, the other type of the checkpoint that is specifically activated in the course of differentiation. We will discuss the evidences that support the link between DNA damage proteins and C2C12 cell differentiation.