bims-iorami 2023-11-12 papers

Issue of 2023–11–12
five papers selected by
Chenxiao Yu, Soochow University

NPJ Aging. 2023 Nov 07. 9(1): 26

Spontaneous p53 activation in middle-aged C57BL/6 mice mitigates the lifespan-extending adaptive response induced by low-dose ionizing radiation.

Masaoki Kohzaki, Keiji Suzuki, Akira Ootsuyama, Ryuji Okazaki.

Understanding the biological effects of low-dose (<100 mGy) ionizing radiation (LDR) is technically challenging. We investigated age-dependent LDR effects using adaptive response experiments in young (7-to 12-week-old) and middle-aged (40-to 62-week-old) C57BL/6 mice. Compared with 3 Gy irradiation, 0.02 Gy preirradiation followed by 3 Gy irradiation prolonged life in young mice but not middle-aged mice. Preirradiation also suppressed irradiation-induced 53BP1 repair foci in the small intestines, splenic apoptosis, and p53 activity in young mice but not middle-aged mice. Young p53+/- C57BL/6 mice did not show these adaptive responses, indicating that insufficient p53 function in young mice mitigated the adaptive responses. Interestingly, p53 activation in middle-aged mice spontaneously became approximately 4.5-fold greater than that in young mice, possibly masking LDR stresses. Furthermore, adaptive responses in young mice, but not in middle-aged mice, suppressed some senescence-associated secretory phenotype (SASP) factors (IL-6, CCL2, CCL5, CXCL1). Thus, LDR-induced adaptive responses associated with specific SASP factors may be attenuated by a combination of reduced DNA damage sensor/transducer function and chronic p53 activation in middle-aged mice.

DOI: https://doi.org/10.1038/s41514-023-00123-3

Cell Mol Immunol. 2023 Nov 07.

Mitochondrial DNA-triggered innate immune response: mechanisms and diseases.

Ming-Ming Hu, Hong-Bing Shu.

Various cellular stress conditions trigger mitochondrial DNA (mtDNA) release from mitochondria into the cytosol. The released mtDNA is sensed by the cGAS-MITA/STING pathway, resulting in the induced expression of type I interferon and other effector genes. These processes contribute to the innate immune response to viral infection and other stress factors. The deregulation of these processes causes autoimmune diseases, inflammatory metabolic disorders and cancer. Therefore, the cGAS-MITA/STING pathway is a potential target for intervention in infectious, inflammatory and autoimmune diseases as well as cancer. In this review, we focus on the mechanisms underlying the mtDNA-triggered activation of the cGAS-MITA/STING pathway, the effects of the pathway under various physiological and pathological conditions, and advances in the development of drugs that target cGAS and MITA/STING.

Keywords: Disease; Innate immunity; MITA/STING; Mitostress; Virus

DOI: https://doi.org/10.1038/s41423-023-01086-x

Biomed Environ Sci. 2023 Oct 20. 36(10): 903-916

Aurora A Kinase Plays a Key Role in Mitosis Skip during Senescence Induced by Ionizing Radiation.

Xu Rui Zhang, Tong Shan Zhang, Ya Nan Zhang, Jun Rui Hua, Ju Fang Wang, Jin Peng He.

Objective: To investigate the fate and underlying mechanisms of G2 phase arrest in cancer cells elicited by ionizing radiation (IR).
Methods: Human melanoma A375 and 92-1 cells were treated with X-rays radiation or Aurora A inhibitor MLN8237 (MLN) and/or p21 depletion by small interfering RNA (siRNA). Cell cycle distribution was determined using flow cytometry and a fluorescent ubiquitin-based cell cycle indicator (FUCCI) system combined with histone H3 phosphorylation at Ser10 (pS10 H3) detection. Senescence was assessed using senescence-associated-β-galactosidase (SA-β-Gal), Ki67, and γH2AX staining. Protein expression levels were determined using western blotting.
Results: Tumor cells suffered severe DNA damage and underwent G2 arrest after IR treatment. The damaged cells did not successfully enter M phase nor were they stably blocked at G2 phase but underwent mitotic skipping and entered G1 phase as tetraploid cells, ultimately leading to senescence in G1. During this process, the p53/p21 pathway is hyperactivated. Accompanying p21 accumulation, Aurora A kinase levels declined sharply. MLN treatment confirmed that Aurora A kinase activity is essential for mitosis skipping and senescence induction.
Conclusion: Persistent p21 activation during IR-induced G2 phase blockade drives Aurora A kinase degradation, leading to senescence via mitotic skipping.

Keywords: G2 arrest; Ionizing radiation; Mitosis skipping; Senescence; Tetraploid

DOI: https://doi.org/10.3967/bes2023.119

Immunity. 2023 Oct 31. pii: S1074-7613(23)00444-2. [Epub ahead of print]

Gasdermin D permeabilization of mitochondrial inner and outer membranes accelerates and enhances pyroptosis.

Gasdermin D (GSDMD)-activated inflammatory cell death (pyroptosis) causes mitochondrial damage, but its underlying mechanism and functional consequences are largely unknown. Here, we show that the N-terminal pore-forming GSDMD fragment (GSDMD-NT) rapidly damaged both inner and outer mitochondrial membranes (OMMs) leading to reduced mitochondrial numbers, mitophagy, ROS, loss of transmembrane potential, attenuated oxidative phosphorylation (OXPHOS), and release of mitochondrial proteins and DNA from the matrix and intermembrane space. Mitochondrial damage occurred as soon as GSDMD was cleaved prior to plasma membrane damage. Mitochondrial damage was independent of the B-cell lymphoma 2 family and depended on GSDMD-NT binding to cardiolipin. Canonical and noncanonical inflammasome activation of mitochondrial damage, pyroptosis, and inflammatory cytokine release were suppressed by genetic ablation of cardiolipin synthase (Crls1) or the scramblase (Plscr3) that transfers cardiolipin to the OMM. Phospholipid scramblase-3 (PLSCR3) deficiency in a tumor compromised pyroptosis-triggered anti-tumor immunity. Thus, mitochondrial damage plays a critical role in pyroptosis.

Keywords: CRLS1; GSDMD; IL-1; PLSCR3; cardiolipin; mitochondria; pyroptosis

DOI: https://doi.org/10.1016/j.immuni.2023.10.004

Cell Death Dis. 2023 11 07. 14(11): 724

DUSP1 protects against ischemic acute kidney injury through stabilizing mtDNA via interaction with JNK.

Lang Shi, Hongchu Zha, Zhou Pan, Jiayi Wang, Yao Xia, Huimin Li, Hua Huang, Ruchi Yue, Zhixia Song, Jiefu Zhu.

The mechanism underlying acute kidney injury (AKI) and AKI-to-Chronic kidney disease (CKD) transition remains unclear, but mitochondrial dysfunction may be a key driving factor. Literature reports suggest that dual-specificity phosphatase 1 (DUSP1) plays a critical role in maintaining mitochondrial function and structural integrity. In this study, ischemic Acute Kidney Injury (AKI) and post-ischemic fibrosis models were established by clamping the renal pedicle with different reperfusion times. To investigate the role of DUSP1, constitutional Dusp1 knockout mice and tubular-specific Sting knockout mice were used. Mitochondrial damage was assessed through electron microscopy observation, measurements of mitochondrial membrane potential, mtDNA release, and BAX translocation. We found that Dusp1 expression was significantly upregulated in human transplant kidney tissue and mouse AKI tissue. Dusp1 gene deletion exacerbated acute ischemic injury, post-ischemic renal fibrosis, and tubular mitochondrial dysfunction in mice. Mechanistically, DUSP1 could directly bind to JNK, and DUSP1 deficiency could lead to aberrant phosphorylation of JNK and BAX mitochondria translocation. BAX translocation promoted mitochondrial DNA (mtDNA) leakage and activated the cGAS-STING pathway. Inhibition of JNK or BAX could inhibit mtDNA leakage. Furthermore, STING knockout or JNK inhibition could significantly mitigate the adverse effects of DUSP1 deficiency in ischemic AKI model. Collectively, our findings suggest that DUSP1 is a regulator for the protective response during AKI. DUSP1 protects against AKI by preventing BAX-induced mtDNA leakage and blocking excessive activation of the cGAS-STING signaling axis through JNK dephosphorylation.

DOI: https://doi.org/10.1038/s41419-023-06247-4