Citations

Aging occurs heterogeneously across organs, leading to progressive tissue dysfunction. Cellular senescence is a stress response triggered by age-associated insults, yet the mechanisms regulating senescence and organ aging remain incompletely understood. Here, we defined a role for lysine-specific demethylase 1 (LSD1) in DNA damage–mediated senescence and organ aging. LSD1 was upregulated in aged organs and senescent cells. In response to natural aging or ionizing radiation–induced DNA damage, LSD1 interacted with and demethylated ATM at lysine 3,016, as confirmed using a newly generated ATM-K3016me antibody. This modification sustained ATM phosphorylation, amplified DNA damage signaling, and delayed checkpoint recovery, promoting senescence and organ aging. Inhibition of LSD1 accelerated ATM dephosphorylation via WIP1, enhanced DNA repair, reduced senescence and DNA damage, and prevented irradiation-induced hair graying. Elimination of senescent cells with senolytics reduced LSD1 protein in aged organs, indicating a feedback loop between LSD1 and senescence. Mechanistically, LSD1 underwent autophagosome-lysosome degradation through interaction with LC3 and Beclin1, and autophagy impairment during DNA damage contributed to LSD1 accumulation in senescent cells. This study revealed LSD1 as a key regulator of DNA damage–induced senescence and organ aging and suggested that targeting LSD1 may attenuate senescence, delay organ aging, and prevent hair graying.

Polycystic kidney disease (PKD) arises from mutations in cilia-associated genes, such as PKD1 and PKD2 , expressed in renal epithelial cells, leading to progressive kidney dysfunction and end-stage kidney disease (ESKD). PKD patients exhibit significant heterogeneity in disease progression, largely due to genetic and environmental modifiers. Like patients, mouse models of PKD also exhibit significant heterogeneity with regards to the gene mutated, age of disease onset, and rate of disease progression. To elucidate the cellular and molecular consequences of these variables, we constructed an integrated single-cell RNA sequencing atlas across mouse models of PKD, mapping changes in cell type composition, gene expression, and intercellular signaling networks across the whole atlas and within individual models. Across models, single cell RNA sequencing (scRNAseq) data revealed increased Spp1 (osteopontin) expression and signaling from PKD-enriched clusters. Global deletion of Spp1 in Pkd1 RC/RC mice resulted in a modest reduction in cyst severity and improved kidney function. From these studies, we created a freely available, searchable website (https://bmblx.bmi.osumc.edu/scPKD/) that can be used to identify cross- and intra-model changes in gene expression, guiding researchers to new therapeutic targets for treating PKD.

Key Points Alanyl-transfer RNA synthetase 1 (AARS1) was upregulated and promoted cyst growth in autosomal dominant polycystic kidney disease. AARS1 promoted lysine lactylation of signal transducer and activator of transcription 3 (K140) and NF-κB p65 (K310), enhancing their phosphorylation, interaction, and transcriptional activity. AARS1 transcriptionally repressed its novel targets, Atg5 and Dusp4, to impair autophagy but activate polycystic kidney disease signaling pathways. Background Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder, characterized by metabolic reprogramming with enhanced glycolysis and lactate accumulation. However, the enzyme that senses lactate and uses it as a substrate for protein lactylation in ADPKD remains unknown. Alanyl-transfer RNA synthetase 1 (AARS1) is a lactate-responsive enzyme with lactyltransferase activity, while its role and mechanisms in ADPKD have not been defined. Methods To investigate the role of AARS1, we generated Pkd1 and Aars1 double conditional knockout Pkd1 fl/fl :Aars1 fl/fl :Ksp-Cre mice and evaluated the effect of AARS1 inhibitor β -alanine in two ADPKD mouse models. Coimmunoprecipitation and Cleavage Under Targets and Tagmentation analyses were performed to identify novel AARS1 substrates and downstream target genes involved in cystogenesis. Results AARS1 was elevated in Pkd1 mutant renal epithelial cells and kidneys, and genetic deletion of Aars1 significantly delayed cyst growth, preserved kidney function, and reduced renal lactylation in Pkd1 mutant mice. Mechanistically, AARS1 promoted lactylation-dependent activation of signal transducer and activator of transcription 3 (STAT3) and NF-κB (p65), specifically at STAT3 K140 and p65 K310, thereby amplifying pro-proliferative and proinflammatory transcriptional programs. AARS1 also associated with promoter regions and mediated histone H3 lysine 14 lactylation, thereby repressing the transcription of Atg5 to impair autophagy and suppressing the transcription of Dusp4 to sustain phosphorylation of cAMP response element–binding protein and retinoblastoma protein. Cytokine signaling through IL-6 and TNF- α further reinforced AARS1 expression through STAT3- and NF-κB–dependent feed-forward loops. Importantly, inhibition of AARS1 with β -alanine markedly slowed cyst progression in Pkd1 mutant mouse models. Conclusions Our study identified AARS1 as a central metabolic sensor linking lactate-driven lysine lactylation to transcriptional, epigenetic, and signaling pathways that drive ADPKD progression.

ABSTRACT Background Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst growth, inflammation, fibrosis, and renal failure. Klotho is a renoprotective protein with antiproliferative, anti-inflammatory, and antioxidant properties, but its mechanistic role in ADPKD remains poorly defined. Methods Klotho expression was analyzed in human ADPKD kidneys, public bulk and single-cell RNA sequencing datasets, Pkd1 mutant renal epithelial cells, and Pkd1 mouse models. The therapeutic effects of recombinant Klotho were evaluated in late-onset Pkd1fl/fl:tamoxifen-Cre mice. Molecular mechanisms were investigated using cell viability assays, western blotting, reverse transcription quantitative polymerase chain reaction (RT-qPCR), immunohistochemistry, ferroptosis assays, DNA methylation analysis, and chromatin immunoprecipitation assay. Results Klotho expression was markedly reduced in human ADPKD kidneys and Pkd1-deficient cells and mice, particularly in distal nephron segments. Recombinant Klotho treatment significantly reduced cyst burden, kidney enlargement, and blood urea nitrogen levels, while decreasing epithelial proliferation and increasing apoptosis in cyst-lining cells. Mechanistically, Klotho suppressed PKD-associated signaling pathways, including protein kinase B (AKT), signal transducer and activator of transcription 3 (STAT3), and retinoblastoma protein (Rb), reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-mediated inflammation via downregulation of Smyd2, and attenuated transforming growth factor-beta (TGF-β)-Smad-dependent renal fibrosis. Klotho also inhibited ferroptosis by upregulating GPX-4 and reducing lipid peroxidation. Epigenetic analyses revealed DNA methyltransferase 1 (DNMT1)-mediated hypermethylation of the Klotho promoter and gene body in ADPKD kidneys, contributing to Klotho silencing. Inhibition of DNMT1 restored Klotho expression, and recombinant Klotho reduced DNMT1 levels, suggesting a negative feedback loop. Conclusions Klotho is epigenetically repressed in ADPKD and functions as a central regulator of cyst growth, inflammation, fibrosis, and ferroptosis. Restoration of Klotho signaling markedly attenuates disease progression in Pkd1 mutant mice, identifying the Klotho–DNMT1 axis as a promising therapeutic target for ADPKD.

Immune checkpoint inhibitors (ICIs) can cause immune-related adverse events (irAEs), with acute interstitial nephritis (ICI-AIN) being the most common irAE. While the exact mechanism remains unclear, upregulation of IFN-γ and TNF-α pathways has been implicated. This study used a humanized chimeric PD-1/PD-L1 mouse model to assess renal effects of ICIs, alone or combined with proinflammatory cytokines, and to test if selective TNF-α blockade could prevent ICI-AIN. Mice were randomly divided into 4 experimental groups: Control, ICI-Only, ICI-Cytokines (ICI-Cyt), and ICI-Block (ICI-TNF-α blockade). Renal function and cytokine profiles were assessed, while kidney tissue was analyzed using microscopy and single-cell RNA-seq. Histology revealed increased renal infiltration of CD4 + /CD8 + T cells in ICI-treated groups and decreased TNF-α expression following TNF-α blockade. Additionally, kidney tissue ELISA demonstrated reduced IFN-γ levels following TNF-α blockade. Plasma IL-6, MCP-1, and TNF-α were lower in ICI-Block mice. Single-cell RNA-seq revealed shifts in immune cell populations and genes of interest including Bcl2a1 , Icos , Il18r1 , Ccr2 , and Jaml . This humanized model replicates ICI-AIN key features, revealing a synergistic role of ICIs and proinflammatory cytokines. TNF-α blockade demonstrated protective effects, supporting its potential role in mitigating the risk of ICI-AIN.

Key Points α Klotho as an antiaging protein can extend the lifespan of healthy animals; serum α Klotho was lower in patients with autosomal dominant polycystic kidney disease. Transgenic α Klotho and recombinant α Klotho delayed cyst growth in Pkd1 mutant mouse kidneys. α Klotho exerted its proapoptotic and anti-inflammatory function through interacting with and destabilizing cellular inhibitor of apoptosis protein 1. Background α -Klotho ( α Klotho) is expressed mainly in the kidney, which is encoded by the KL gene, existing in a membrane-bound form and a soluble circulating form. Soluble serum α Klotho was lower in patients with autosomal dominant polycystic kidney disease (ADPKD). However, the role of α Klotho in ADPKD remains unknown. Methods To investigate the roles of α Klotho in ADPKD, we generated transgenic α Klotho and Pkd1 mutant Pkd1-HOMO-KL Tg mice to evaluate cyst growth and investigated underlying mechanisms with single-cell RNA sequencing analysis. Results We showed that α Klotho was lower in diverse kidney cell types in Pkd1 mutant kidneys, which was restored by transgenic α Klotho. We identified differential expression genes and pathways mediated by transgenic α Klotho at single-cell resolution and determined the cytokines and their receptors mediated cell-to-cell communication networks in Pkd1 mutant and Pkd1-HOMO-KL Tg kidneys by CellChat analysis. We further showed that α Klotho exerted a proapoptotic and anti-inflammatory function through interacting with and destabilizing cellular inhibitor of apoptosis protein 1, which disturbed TNF and its receptor mediated prosurvival complex, leading to ( 1 ) the formation of predeath complex to increase cystic cell death and ( 2 ) the decrease of the activation of NF-κB, the expression of cytokines, and the recruitment of macrophages, resulting in a delay of cyst growth. Treatment with recombinant α Klotho also delayed cyst growth in Pkd1 mutant kidneys. Conclusions This study defined an unknown role and mechanism of α Klotho in the regulation of a TNF-dependent cystic cell apoptosis and inflammation in Pkd1 mutant kidneys.

Sustained injury to renal tubular epithelial cells (TECs), driven by excessive autophagy, is a critical mechanism underlying kidney fibrosis. Our previous work identified JLP — a TEC-expressed scaffolding protein — as an endogenous antifibrotic factor that counteracts TGF-β1–induced autophagy and fibrogenesis. However, the mechanism underlying JLP downregulation in renal fibrosis remains unclear. Here, we delineated a TGF-β1/LEF1/β-catenin/JLP axis that governs TEC autophagy through a dichotomous regulatory circuit. Under physiological conditions, low levels of β-catenin and LEF1 with minimal nuclear localization permitted normal JLP expression, which in turn maintained autophagy in check. In contrast, during renal injury, TGF-β1 promoted the expression and nuclear translocation of β-catenin and LEF1, which together suppressed JLP transcription. This loss of JLP-mediated inhibition led to unchecked autophagy and exacerbated fibrotic damage. Analyses of kidney tissues from patients with CKD, murine fibrotic kidneys, and cultured HK-2 cells confirmed consistent JLP downregulation accompanied by upregulation and nuclear accumulation of LEF1 and β-catenin. Therapeutic intervention using the β-catenin/LEF1 inhibitor iCRT3 or LEF1-targeted silencing in murine fibrosis models restored JLP expression, attenuated TEC autophagy, and ameliorated renal fibrosis. These findings revealed an autoregulatory circuit controlling TEC autophagy and fibrogenesis, and supported LEF1 and β-catenin as potential therapeutic targets in CKD.

Abstract Single‐molecule immunoassay is a reliable technique for the detection and quantification of low‐abundance blood biomarkers, which are essential for early disease diagnosis and biomedical research. However, current single‐molecule methods predominantly rely on endpoint detection and necessitate signal amplification via labeling, which brings a variety of unwanted effects, like matrix effect and autofluorescence interference. This study introduces a real‐time mass imaging‐based label‐free single‐molecule immunoassay (LFSMiA). Featuring plasmonic scattering microscopy‐based mass imaging, a 2‐step sandwich assay format enables background reduction, minimization of matrix effect by dynamic tracking of single binding events, and fully leveraging real‐time data for improved measurement precision through a Bayesian Gaussian process model, the LFSMiA enables ultra‐sensitive and direct protein detection at the single‐molecule level in neat blood sample matrices. LFSMiA measurement is demonstrated for interleukin‐6 and prostate‐specific antigen in buffer, undiluted serum, and whole blood with sub‐femtomolar detection limits and eight logs of dynamic ranges. Moreover, comparable performance is achieved with an inexpensive miniaturized setup. To show its translational potential to clinical settings and point‐of‐care diagnostics, N‐terminal pro‐B‐type natriuretic peptide is examined in patient whole blood samples using the LFSMiA and results in a strong linear correlation (r > 0.99) with standard clinical lab results.