Aging
Abstract
Authors
Nishanth S. Sadagopan, Rushmin Khazanchi, Rishi Jain, Amy B. Heimberger, Stephen T. Magill
Abstract
Despite effective antiretroviral therapy (ART), transcriptionally competent HIV-1 reservoirs persist and contribute to persistent immune activation in people living with HIV (PWH). HIV-1-infected macrophages are important mediators of chronic innate immune activation, though mechanisms remain unclear. We previously reported that nuclear export and cytoplasmic expression of HIV-1 intron-containing RNA (icRNA) activates mitochondrial antiviral signaling protein (MAVS)-mediated type I interferon (IFN) responses in macrophages. In this study, we demonstrate an essential role of melanoma differentiation-associated protein 5 (MDA5) in sensing HIV-1 icRNA and promoting MAVS-dependent IRF5 activation in macrophages. Suppression of MDA5, but not RIG-I expression nor disruption of endosomal TLR pathway, abrogated HIV-1 icRNA-induced type I IFN responses and IP-10 expression in macrophages. Furthermore, induction of IP-10 in macrophages upon HIV-1 icRNA sensing by MDA5 was dependent on IRF5. Additionally, monocytes and MDMs from older (>50 years) individuals exhibit constitutively higher levels of IRF5 expression compared to younger (<35 years) individuals, and HIV-1 icRNA induced IP-10 expression was significantly enhanced in older macrophages, which was attenuated upon ablation of IRF5 expression suggesting that IRF5 functions as a major mediator of pro-inflammatory response downstream of MDA5-dependent HIV-1 icRNA sensing, dysregulation of which might contribute to chronic inflammation in older PWH.
Authors
Sita Ramaswamy, Hisashi Akiyama, Jacob Berrigan, Andrés A. Quiñones-Molina, Alex J. Olson, Yunhan Chen, YanMei Liang, Andrew J. Henderson, Archana Asundi, Manish Sagar, Suryaram Gummuluru
Abstract
The nucleolus is a membraneless organelle and an excellent stress sensor. Any changes in its architecture or composition lead to nucleolar stress, resulting in cell cycle arrest and interruption of ribosomal activity, critical factors in aging and cancer. In this study, we identified and described the pivotal role of the RNA-binding protein (RBP) HNRNPK in ribosome and nucleolar dynamics. We developed an in vitro model of endogenous HNRNPK overexpression and an in vivo mouse model of ubiquitous HNRNPK overexpression. These models showed disruptions in translation and caused alterations in the nucleolar structure, resulting in p53-dependent nucleolar stress, cell cycle arrest, senescence, and bone marrow failure phenotype, similar to what is observed in patients with ribosomopathies. Together, our findings identify HNRNPK as a master regulator of ribosome biogenesis (RiBi) and nucleolar homeostasis through p53, providing a new perspective on the orchestration of nucleolar integrity, ribosome function and cellular senescence.
Authors
Pedro Aguilar-Garrido, María Velasco-Estévez, Miguel Ángel Navarro-Aguadero, Alvaro Otero-Sobrino, Marta Ibañez-Navarro, Miguel Ángel Marugal, María Hernández-Sánchez, Prerna Malaney, Ashley Rodriguez, Oscar Benitez, Xiaorui Zhang, Marisa J.L. Aitken, Alejandra Ortiz-Ruiz, Diego Megias, Manuel Pérez-Martínez, Gadea Mata, Jesús Gomez, Miguel Lafarga, Orlando Dominguez, Osvaldo Graña-Castro, Eduardo Caleiras, Pilar Ximenez-Embun, Marta Isasa, Paloma J. de Andrés, Sandra Rodriguez-Perales, Raul Torres-Ruiz, Enrique Revilla, Rosa María García-Martín, Daniel Azorín, Josune Zubicaray, Julian Sevilla, Oleksandra Sirozh, Vanesa Lafarga, Joaquín Martinez-Lopez, Sean M. Post, Miguel Gallardo
Abstract
Neuronal hyperexcitability precedes synapse loss in certain neurodegenerative diseases, yet the synaptic membrane interactions and downstream signaling events remain unclear. The disordered amino terminus of the prion protein (PrPC) has been implicated in aberrant signaling in prion and Alzheimer’s disease. To disrupt neuronal interactions and signaling linked to the amino terminus, here we CRISPR-engineered a knock-in mouse expressing mutant PrPC (G92N), generating an N-linked glycosylation site between two functional motifs. Mice developed seizures and necrosis of hippocampal pyramidal neurons, similar to prion-infected mice and consistent with excitotoxicity. Phosphoproteomics revealed phosphorylated glutamate receptors and calcium-sensitive kinases, including protein kinase C (PKC). Additionally, 92N-PrPC-expressing neurons show persistent calcium influx as well as dendritic beading, which was rescued by an NMDA receptor antagonist. Finally, survival of Prnp92N mice was prolonged by blocking active NMDA receptor channels. We propose dysregulated PrPC – NMDA receptor - induced signaling can trigger excitatory – inhibitory imbalance, spongiform degeneration, and neurotoxicity, and that calcium dysregulation is central to PrPC-linked neurodegeneration.
Authors
Joie Lin, Julia A. Callender, Joshua E. Mayfield, Daniel B. McClatchy, Daniel Ojeda-Juárez, Mahsa Pourhamzeh, Katrin Soldau, Timothy D. Kurt, Garrett A. Danque, Helen K. Khuu, Josephina E. Ronson, Donald P. Pizzo, Yixing Du, Maxwell A. Gruber, Alejandro M. Sevillano, Jin Wang, Christina D. Orrú, Joy Chen, Gail Funk, Patricia Aguilar-Calvo, Brent D. Aulston, Subhojit Roy, Jong M. Rho, Jack D. Bui, Alexandra C. Newton, Stuart A. Lipton, Byron Caughey, Gentry N. Patrick, Kim Doré, John R. Yates III, Christina J. Sigurdson
Abstract
The histopathological neurons in the brain tissue of drug-resistant epilepsy exhibit aberrant cytoarchitecture and imbalanced synaptic circuit function. However, the gene expression changes of these neurons remain unknown, making it difficult to determine the diagnosis or to dissect the mechanism of drug-resistant epilepsy. By integrating whole-cell patch clamp recording and single-cell RNA-seq approaches, we identified a transcriptionally distinct subset of cortical pyramidal neurons. These neurons highly expressed genes CDKN1A (P21), CCL2, and NFKBIA, which associate with mTOR pathway, inflammatory response, and cellular senescence. We confirmed the expression of senescent marker genes in a subpopulation of cortical pyramidal neurons with enlarged soma size in the brain tissue of drug-resistant epilepsy. We further revealed the expression of senescent cell markers P21, P53, COX2, γ-H2AX, and β-Gal, and reduction of nuclear integrity marker Lamin B1 in histopathological neurons in the brain tissue of patients with drug-resistant epilepsy with different pathologies, but not in control brain tissue with no history of epilepsy. Additionally, chronic, but not acute, epileptic seizures induced senescent marker expression in cortical neurons in mouse models of drug-resistant epilepsy. These results provide important molecular markers for histopathological neurons and what we believe to be new insights into the pathophysiological mechanisms of drug-resistant epilepsy.
Authors
Qianqian Ge, Jiachao Yang, Fei Huang, Xinyue Dai, Chao Chen, Jingxin Guo, Mi Wang, Mengyue Zhu, Yijie Shao, Yuxian Xia, Yu Zhou, Jieqiao Peng, Suixin Deng, Jiachen Shi, Yiqi Hu, Huiying Zhang, Yi Wang, Xiaoqun Wang, Xiao-Ming Li, Zhong Chen, Yousheng Shu, Jun-Ming Zhu, Jianmin Zhang, Ying Shen, Shumin Duan, Shengjin Xu, Li Shen, Jiadong Chen
Abstract
Posttranslational modification (PTM) of the amyloid precursor protein (APP) plays a critical role in Alzheimer’s disease (AD). Recent evidence reveals that lactylation modification, as a novel PTM, is implicated in the occurrence and development of AD. However, whether and how APP lactylation contributes to both the pathogenesis and cognitive function in AD remains unknown. Here, we observed a reduction in APP lactylation in AD patients and AD model mice and cells. Proteomic mass spectrometry analysis further identified lysine 612 (APP-K612la) as a crucial site for APP lactylation, influencing APP amyloidogenic processing. A lactyl-mimicking mutant (APPK612T) reduced amyloid-β peptide (Aβ) generation and slowed down cognitive deficits in vivo. Mechanistically, APPK612T appeared to facilitate APP trafficking and metabolism. However, lactylated APP entering the endosome inhibited its binding to BACE1, suppressing subsequent cleavage. Instead, it promoted protein interaction between APP and CD2-associated protein (CD2AP), thereby accelerating the endosomal-lysosomal degradation pathway of APP. In the APP23/PS45 double-transgenic mouse model of AD, APP-Kla was susceptible to L-lactate regulation, which reduced Aβ pathology and repaired spatial learning and memory deficits. Thus, these findings suggest that targeting APP lactylation may be a promising therapeutic strategy for AD in humans.
Authors
Qiuyun Tian, Junjie Li, Bin Wu, Yayan Pang, Wenting He, Qian Xiao, Jiaojiao Wang, Lilin Yi, Na Tian, Xiuyu Shi, Lei Xia, Xin Tian, Mulan Chen, Yepeng Fan, Boqing Xu, Yuhan Tao, Weihong Song, Yehong Du, Zhifang Dong
Endothelial BMAL1 decline during aging leads to bone loss by destabilizing extracellular fibrillin-1
Abstract
The occurrence of aging is intricately associated with alterations in circadian rhythms that coincide with stem cell exhaustion. Nonetheless, the extent to which the circadian system governs skeletal aging remains inadequately understood. Here, we noticed that skeletal aging in male mice was accompanied by a decline in a core circadian protein, BMAL1, especially in bone marrow endothelial cells (ECs). Using male mice with endothelial KO of aryl hydrocarbon receptor nuclear translocator–like protein 1 (Bmal1), we ascertained that endothelial BMAL1 in bone played a crucial role in ensuring the stability of an extracellular structural component, fibrillin-1 (FBN1), through regulation of the equilibrium between the extracellular matrix (ECM) proteases thrombospondin type 1 domain–containing protein 4 (THSD4) and metalloproteinase with thrombospondin motifs 4 (ADAMTS4), which promote FBN1 assembly and breakdown, respectively. The decline of endothelial BMAL1 during aging prompted excessive breakdown of FBN1, leading to persistent activation of TGF-β/SMAD3 signaling and exhaustion of bone marrow mesenchymal stem cells. Meanwhile, the free TGF-β could promote osteoclast formation. Further analysis revealed that activation of ADAMTS4 in ECs lacking BMAL1 was stimulated by TGF-β/SMAD3 signaling through an ECM-positive feedback mechanism, whereas THSD4 was under direct transcriptional control by endothelial BMAL1. Our investigation has elucidated the etiology of bone aging in male mice by defining the role of ECs in upholding the equilibrium within the ECM, consequently coordinating osteogenic and osteoclastic activities and retarding skeletal aging.
Authors
Ying Yin, Qingming Tang, Jingxi Yang, Shiqi Gui, Yifan Zhang, Yufeng Shen, Xin Zhou, Shaoling Yu, Guangjin Chen, Jiwei Sun, Zhenshuo Han, Luoying Zhang, Lili Chen
Abstract
The aging process is characterized by cellular functional decline and increased susceptibility to infections. Understanding the association between virus infection and aging is crucial for developing effective strategies against viral infections in older individuals. However, the relationship between Kaposi's sarcoma-associated herpesvirus (KSHV) infection, a cause of Kaposi's sarcoma prevalent among the elderly without HIV infection, and cellular senescence remains enigmatic. This study uncovers a fascinating link between cellular senescence and enhanced KSHV infectivity in human endothelial cells. Through a comprehensive proteomic analysis, we identified caveolin-1 and CD109 as novel host factors significantly upregulated in senescent cells that promote KSHV infection. Remarkably, CRISPR-Cas9-mediated knockout of these factors reduced KSHV binding and entry, leading to decreased viral infectivity. Furthermore, surface plasmon resonance analysis and confocal microscopy revealed a direct interaction between KSHV virions and CD109 on the cell surface during entry, with recombinant CD109 protein exhibiting an intriguing ability to inhibit infection by blocking virion binding. These findings uncover a previously unrecognized role of cellular senescence in enhancing KSHV infection through upregulation of specific host factors and provide novel insights into the complex interplay between aging and viral pathogenesis.
Authors
Myung-Ju Lee, Jun-Hee Yeon, Jisu Lee, Yun Hee Kang, Beom Seok Park, Joo Hee Park, Sung-Ho Yun, Dagmar Wirth, Seung-Min Yoo, Changhoon Park, Shou-Jiang Gao, Myung-Shin Lee
Abstract
Parkinson’s disease (PD) is characterized by age-dependent neurodegeneration and the accumulation of toxic phosphorylated α-synuclein (pS129-α-syn). The mechanisms underlying these crucial pathological changes remain unclear. Mutations in parkin RBR E3 ubiquitin protein ligase (PARK2), the gene encoding parkin that is phosphorylated by PTEN-induced putative kinase 1 (PINK1) to participate in mitophagy, cause early onset PD. However, current parkin-KO mouse and pig models do not exhibit neurodegeneration. In the current study, we utilized CRISPR/Cas9 technology to establish parkin-deficient monkey models at different ages. We found that parkin deficiency leads to substantia nigra neurodegeneration in adult monkey brains and that parkin phosphorylation decreases with aging, primarily due to increased insolubility of parkin. Phosphorylated parkin is important for neuroprotection and the reduction of pS129-α-syn. Consistently, overexpression of WT parkin, but not a mutant form that cannot be phosphorylated by PINK1, reduced the accumulation of pS129-α-syn. These findings identify parkin phosphorylation as a key factor in PD pathogenesis and suggest it as a promising target for therapeutic interventions.
Authors
Rui Han, Qi Wang, Xin Xiong, Xiusheng Chen, Zhuchi Tu, Bang Li, Fei Zhang, Chunyu Chen, Mingtian Pan, Ting Xu, Laiqiang Chen, Zhifu Wang, Yanting Liu, Dajian He, Xiangyu Guo, Feng He, Peng Wu, Peng Yin, Yunbo Liu, Xiaoxin Yan, Shihua Li, Xiao-Jiang Li, Weili Yang
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare disease caused by the expression of progerin, an aberrant protein produced by a point mutation in the LMNA gene. HGPS patients show accelerated aging and die prematurely mainly from complications of atherosclerosis such as myocardial infarction, heart failure, or stroke. However, the mechanisms underlying HGPS vascular pathology remain ill defined. We used single-cell RNA sequencing to characterize the aorta in progerin-expressing LmnaG609G/G609G mice and wild-type controls, with a special focus on endothelial cells (ECs). HGPS ECs showed gene expression changes associated with extracellular matrix alterations, increased leukocyte extravasation, and activation of the yes-associated protein 1/transcriptional activator with PDZ-binding domain (YAP/TAZ) mechanosensing pathway, all validated by different techniques. Atomic force microscopy experiments demonstrated stiffer subendothelial extracellular matrix in progeroid aortas, and ultrasound assessment of live HGPS mice revealed disturbed aortic blood flow, both key inducers of the YAP/TAZ pathway in ECs. YAP/TAZ inhibition with verteporfin reduced leukocyte accumulation in the aortic intimal layer and decreased atherosclerosis burden in progeroid mice. Our findings identify endothelial YAP/TAZ signaling as a key mechanism of HGPS vascular disease and open a new avenue for the development of YAP/TAZ targeting drugs to ameliorate progerin-induced atherosclerosis.
Authors
Ana Barettino, Cristina González-Gómez, Pilar Gonzalo, María J. Andrés-Manzano, Carlos R. Guerrero, Francisco M. Espinosa, Rosa M. Carmona, Yaazan Blanco, Beatriz Dorado, Carlos Torroja, Fátima Sánchez-Cabo, Ana Quintas, Alberto Benguría, Ana Dopazo, Ricardo García, Ignacio Benedicto, Vicente Andrés
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ISSN: 0021-9738 (print), 1558-8238 (online)