Research
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.195836.
Abstract
There are two subtypes of myotonic dystrophy, DM1 and DM2, each caused by repeat expansion mutations. The leading pathogenic mechanism is RNA mediated toxicity whereby (C)CUG expansions sequester the muscleblind-like (MBNL) family of RNA binding proteins. However, key differences exist in muscle involvement patterns and histopathology between DM1 and DM2. The cause of these disparities both in how the muscles are affected within each disease and between the two diseases is unknown, and it is unclear if current DM mouse models recapitulate these differences or develop differential muscle susceptibility. Here, we examined the expression of disease-relevant genes across healthy human muscles from a transcriptomic atlas and collected a series of muscles from Mbnl knockout mice to evaluate characteristic histologic and molecular features of DM pathology. Our results indicate that MBNL loss discordantly affects muscles, likely through a splicing independent mechanism, and results in a fiber atrophy profile more like DM1 than DM2. These findings point to a predominant role for MBNL loss in muscle pattern involvement in DM1, provide further evidence for additional DM2 pathomechanisms, and have important implications for muscle choice when performing analyses in new mouse models and evaluating therapeutic modalities and biomarkers.
Authors
Mackenzie L. Davenport, Amaya Fong, Gloria Montoya-Vazquez, Maria Fernanda Alves de Moura, Jodi L. Bubenik, Maurice S. Swanson
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.190149.
Abstract
Radiotherapy triggers chemokine release and leukocyte infiltration in pre-clinical models through activation of the senescence-associated secretory phenotype (SASP). However, effects of irradiation on senescence and SASP in human tissue and in the context of particle radiotherapy remain unclear. Here, we analyzed chemokine patterns after radiotherapy of human pancreatic tumors and cancer cell lines. We show that irradiated tumor cells co-express SASP chemokines in defined modules. These chemokine modules correlated with infiltration of distinct leukocyte subtypes expressing cognate receptors. We developed a patient-derived pancreatic tumor explant system, which confirmed our identified radiation-induced chemokine modules. Chemokine modules were partially conserved in cancer cells in response to photon and particle irradiation showing a dose-dependent plateau effect and induced subsequent migration of NK and T cell populations. Hence, our work reveals redundant interactions of cancer cells and immune cells in human tissue, suggesting that targeting multiple chemokines is required to efficiently perturb leukocyte infiltration after photon or particle radiotherapy.
Authors
Joscha A. Kraske, Michael M. Allers, Aleksei Smirnov, Bénédicte Lenoir, Azaz Ahmed, Meggy Suarez-Carmona, Mareike Hampel, Damir Krunic, Alexandra Tietz-Dalfuß, Tizian Beikert, Jonathan M. Schneeweiss, Stephan Brons, Dorothee Albrecht, Thuy Trinh, Muzi Liu, Nathalia A. Giese, Christin Glowa, Jakob Liermann, Ramon Lopez Perez, Dirk Jäger, Jürgen Debus, Niels Halama, Peter E. Huber, Thomas Walle
Abstract
FOXP3+ Treg cells are critical for immune tolerance. Genetic deletion of the Forkhead domain containing proteins of the FOXP-subfamily member FOXP1 from Tregs results in impaired function associated with reduced CD25 expression and IL-2 signaling, but to date the only other FOXP family member expressed in Tregs, FOXP4, has been minimally studied. To investigate the potential functional interactions among FOXP family members in Treg cells, we specifically deleted Foxp1, Foxp4 or both in FOXP3+ committed Treg cells in mice. Our findings show that mice with combined, but not individual, deficiency in FOXP1 and FOXP4 exhibit lymphoproliferation, inflammation, autoimmunity, and early lethality. The combined absence of FOXP1 and FOXP4 in Tregs results in an activated/effector-like phenotype with compromised suppressive function in peripheral lymphoid organs, an enhanced germinal center response and proinflammatory cytokine production. We further show that FOXP1 and FOXP4 bind to Il2ra promoter regions to regulate CD25 expression in Tregs. Through pairwise comparison among mouse strains with Treg specific deletion of Foxp1, Foxp4 or both, our findings indicate a non-redundant but insufficient role of FOXP4 in Treg cell function.
Authors
Dachuan Dong, Vishal J. Sindhava, Ananthakrishnan Ganesan, Martin S. Naradikian, Tom L. Stephen, Andrew Frisch, Kristen M. Valentine, Elizabeth Buza, Karla R. Wiehagen, Michael P. Cancro, Edward E. Morrisey, Haley Tucker, Katrina K. Hoyer, Purvesh Khatri, Jonathan S. Maltzman
Abstract
Pathological cardiac remodeling is associated with the reactivation of fetal genes, yet the extent of the heart’s fetal gene program and its impact on proteome compositions remain incompletely understood. Here, using a new proteome-wide protein ratio quantification strategy with mass spectrometry, we identify pervasive isoform usage shifts in fetal and postnatal mouse hearts, involving 145 pairs of highly homologous paralogs and alternative splicing-derived isoform proteins. Proteome-wide ratio comparisons readily rediscover hallmark fetal gene signatures in muscle contraction and glucose metabolism pathways, while revealing novel isoform usage in mitochondrial and gene expression proteins, including PPA1/PPA2, ANT1/ANT2, and PCBP1/PCBP2 switches. Paralogs with differential fetal usage tend to be evolutionarily recent, consistent with functional diversification. Alternative splicing adds another rich source of fetal isoform usage differences, involving PKM M1/M2, GLS-1 KGA/GAC, PDLIM5 long/short, and other spliceoforms. When comparing absolute protein proportions, we observe a partial reversion toward fetal gene usage in pathological hearts. In summary, we present a ratiometric catalog of paralogs and spliceoform pairs in the cardiac fetal gene program. More generally, the results demonstrate the potential of applying the proteome-wide ratio test concept to discover new regulatory modalities beyond differential gene expression.
Authors
Yu Han, Shaonil Binti, Sara A. Wennersten, Boomathi Pandi, Dominic C.M. Ng, Edward Lau, Maggie P.Y. Lam
Abstract
Anemia is a common and disabling complication of chronic kidney disease (CKD). Current therapies can be burdensome, and full correction of anemia is limited by cardiovascular side effects. New approaches that may offer additional therapeutic options are needed. We explored the anti-anemic effects of erythroferrone, an erythroid hormone that induces iron mobilization by suppressing the master iron-regulatory hormone hepcidin. In a preclinical murine model of adenine-induced CKD, transgenic augmentation of erythroferrone mobilized iron, increased hemoglobin concentrations by approximately 2 g/dl, and modestly improved renal function without affecting systemic or renal inflammation, fibrosis, or markers of mineral metabolism. This study supports the concept that therapeutic augmentation of erythroferrone is a promising approach for alleviating CKD-associated anemia.
Authors
Brian Czaya, Joseph D. Olivera, Moya Zhang, Amber Lundin, Christian D. Castro Andrade, Grace Jung, Mark R. Hanudel, Elizabeta Nemeth, Tomas Ganz
Abstract
Regulatory T cells (Tregs) are essential for peripheral tolerance and depend on TCR and IL-2R signaling for their homeostasis and function. In mice, IL-2-dependent BLIMP-1 contributes to Treg homeostasis. BLIMP-1 is a major transcriptional hub in human Tregs, but its mechanisms of action remain undefined. Here, using CRISPR/Cas9 ablation, we show that BLIMP-1 limits human Treg proliferation, but supports IL-10, CTLA4, several immune checkpoints, including CEACAM1, and Treg functional activity. BLIMP-1 restrains Treg expansion to IL-2 by downregulating CD25 and IL-2R signaling, and by enhancing CEACAM1 expression, which in turn inhibits responsiveness to CD3/CD28 signaling and activation of mTOR. Prolonged IL-2R signaling optimizes BLIMP-1 expression, supporting chromosomal opening of CEACAM1 to increased CEACAM1 expression through STAT5- and BLIMP-1-driven enhancers. Correspondingly, CEACAM1 is highly induced on Tregs from autoimmune patients undergoing low-dose IL-2 therapy, and these Tregs showed reduced proliferation. A humanized mouse model of xenogeneic graft versus host disease demonstrates that BLIMP-1 normally promotes, while CEACAM1 restrains, Treg suppressive activity. Collectively, our findings reveal that BLIMP-1 and CEACAM1 function in an IL-2-dependent feedback loop to restrain Treg proliferation and affect suppressive function. CEACAM1 also acts as a highly selective biomarker of IL-2R signaling in human T cells.
Authors
Ying Ding, Aixin Yu, Milos Vujanac, Sabrina N. Copsel, Alejandro Moro, Luis Nivelo, Molly Dalzell, Nicolas Tchitchek, Michelle Rosenzwajg, Alejandro V. Villarino, Robert B. Levy, David Klatzmann, Thomas R. Malek
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.182880.
Abstract
Bronchopulmonary dysplasia (BPD), a prevalent and chronic lung disease affecting premature newborns, results in vascular rarefaction and alveolar simplification. Although the vasculature has been recognized as a main player in this disease, the recently found capillary heterogeneity and cellular dynamics of endothelial subpopulations in BPD remain unclear. Here, we show Cap2 cells are damaged during neonatal hyperoxic injury, leading to their replacement by Cap1 cells which, in turn, significantly decline. Single cell RNA-seq identifies the activation of numerous p53 target genes in endothelial cells (ECs), including Cdkn1a (p21). While global deletion of p53 results in worsened vasculature, endothelial-specific deletion of p53 reverses the vascular phenotype and improves alveolar simplification during hyperoxia. This recovery is associated with the emergence of a transitional EC state, enriched for oxidative stress response genes and growth factors. Notably, this transitional EC gene signature is conserved in an aberrant capillary population identified in human BPD with pulmonary hypertension, underscoring the biological and clinical relevance of our findings. These results reveal a key role for p53 in maintaining endothelial lineage fidelity during pulmonary capillary repair following hyperoxic injury and highlight the critical contribution of the endothelium to BPD pathogenesis.
Authors
Lisandra Vila Ellis, Jonathan D. Bywaters, Amanda Ceas, Yun Liu, Jennifer M.S. Sucre, Jichao Chen
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.190918.
Abstract
Biallelic variants in SCN1B, encoding the voltage-gated sodium channel β1/β1B subunits, are linked to DEE52, a developmental and epileptic encephalopathy with a high risk of Sudden Unexpected Death in Epilepsy (SUDEP). DEE52 patients present clinically with Dravet syndrome or the more severe early infantile DEE. SCN1B is expressed in brain and heart in humans and in mice. Thus, we have proposed that, in addition to generalized seizures, cardiac arrhythmia may play a role in SUDEP. Mice with homozygous expression of the DEE52 variant Scn1b-c.265C>T, predicting p.R89C, have spontaneous and hyperthermia-induced generalized seizures and SUDEP. Here we conducted cardiac characterization of Scn1b-c.265C>T mice and studied induced pluripotent stem cell cardiomyocytes (iPSC-CMs) derived from two SCN1B-c.265C>T DEE52 patients. Scn1bC89/C89 mouse CMs showed increased transient outward potassium current (Ito) density and heart sections revealed ventricular fibrosis. Scn1bC89/C89 mice were susceptible to pacing-induced cardiac arrhythmias. Patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T variant expression showed increased sodium current (INa), late INaL, and Ito current densities. We conclude that, while mouse and human cardiac AP waveforms have critical differences, increased Ito is common to both models of DEE52. Overall, our data suggest that electrical and structural substrates may lead to arrhythmias and contribute to SUDEP in DEE52.
Authors
Roberto Ramos-Mondragon, Shuyun Wang, Nnamdi Edokobi, Qinghua Liu, Xiaotan Qiao, Maya Shih, Louis T. Dang, Yao-Chang Tsan, Katalin Štěrbová, Adam S. Helms, Sarah Weckhuysen, Luis F. Lopez-Santiago, Jack M. Parent, Lori L. Isom
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.186290.
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 or PKD2, which encode polycystin-1 (PC1) and polycystin-2 (PC2) respectively. These proteins are thought to form a signaling complex that can flux cations including calcium. One of the earliest symptoms in ADPKD is a decline in the concentrating ability of the kidneys, occurring prior to cyst formation. We reasoned that hyperosmolality stimulates the polycystin complex, and that the loss of this function impairs water reabsorption. We found that hyperosmolality resulted in the phosphorylation of a microtubule associated protein 4 (MAP4) in a PC1-dependent manner which then elicited ER-localized PC2 calcium signals. ER-localized PC2 hyperosmotic calcium signals were required for trafficking of the water channel aquaporin (AQP2). Pre-cystic PC1-KO and PC2-KO murine kidneys had cytosolic localized AQP2, and diluted urine compared to their respective controls. Kidney tissue sections from ADPKD patients showed decreased AQP2 apical membrane localization in cystic and non-cystic tubules. Our study demonstrates that osmolality is a physiological stimulus of the polycystin complex, and loss of polycystin osmosensing results in impaired water reabsorption via AQP2. This likely contributes to the declined concentrating ability of the kidneys and high circulating vasopressin levels in ADPKD patients.
Authors
Karla M. Márquez-Nogueras, Ryne M. Knutila, Virdjinija Vuchkovska, Charlie Yang, Patricia Outeda, Darren P. Wallace, Ivana Y. Kuo
Abstract
Radiation-induced lymphopenia (RIL) remains a challenging side effect of radiation therapy, often associated with poor prognosis and reduced overall survival. Although CD8+ T cells are highly radiosensitive, the dynamics of quantitative and qualitative changes to the CD8 T cell pool following exposure to high doses of ionizing radiation (IR) remains understudied. Herein, we sought to determine the long-term impact of sublethal whole body irradiation (WBI) on antigen (Ag)-inexperienced CD8 T cell pool, comprised of naïve (TN) and virtual memory (TVM) CD8+ T cells. We show that although both TN and TVM cells gradually regenerate after WBI-induced loss, TN recovery only occurs through de novo thymic production. Despite the numerical restoration, the subset and phenotypic composition of post-recovery Ag-inexperienced CD8+ T cells do not qualitatively recapitulate the pre-WBI state. Specifically, the frequency of TVM cells is increased, especially during the early stages of recovery. Within the TN subset, a lasting overrepresentation of Ly6C+CD122+ cells and an altered TCR clonotype diversity are also observed. Overall, our data highlight the dynamic changes to the Ag-inexperienced CD8+ T cell pool upon recovery from RIL.
Authors
Mohammad Heidarian, Shravan K. Kannan, Whitney Swanson, Thomas S. Griffith, John T. Harty, Vladimir P. Badovinac
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