Jain et al. report that a tubulin tyrosine ligase mutant causes hypertrophy in patient-derived and CRISPR gene-edited induced pluripotent stem cell–derived (iPSC-derived) cardiomyocytes due to perturbation of tubulin tyrosination. The cover image shows patient iPSC-derived cardiomyocytes displaying the meshwork of detyrosinated α-tubulin (black).
The cellular etiology of seizures in CLN2 disease, a childhood-onset neurodegenerative lysosomal storage disorder caused by a deficiency of tripeptidyl peptidase 1 (TPP1), remains elusive. Given that Cln2R207X/R207X mice display fatal spontaneous seizures and an early loss of several cortical GABAergic interneuron populations, we hypothesized that these two events might be causally related. To study the cell-autonomous effects of interneuron-specific TPP1 deficiency, we first generated a transgenic mouse expressing loxP-flanked lysosomal membrane-tethered TPP1 (TPP1LAMP1) on the Cln2R207X/R207X genetic background, and then crossed TPP1LAMP1 mice with Vgat-Cre mice. These Vgat-Cre; TPP1LAMP1 mice accumulated storage in cortical and striatal interneurons. Vgat-Cre; TPP1LAMP1 mice also died more readily after pentylenetetrazole-induced seizures, indicating that interneuron-specific TPP1 deficiency renders these mice more susceptible to seizure-induced mortality. We also selectively activated interneurons using Designer Receptor Exclusively Activated by Designer Drugs (DREADDs) in Vgat-Cre; Cln2R207X/R207X mice. Electroencephalogram monitoring revealed that DREADD-mediated activation of interneurons markedly accelerated the onset of spontaneous seizures and seizure-associated death in Vgat-Cre; Cln2R207X/R207X mice, suggesting that modulating interneuron activity can exacerbate epileptiform abnormalities. Taken together, these results provide new mechanistic insights into the underlying etiology of seizures and premature death that characterize CLN2 disease.
Keigo Takahashi, Nicholas R. Rensing, Elizabeth M. Eultgen, Letitia L. Williams, Sophie H. Wang, Hemanth R. Nelvagal, Steven Q. Le, Marie S. Roberts, Balraj Doray, Edward B. Han, Patricia I. Dickson, Michael Wong, Mark S. Sands, Jonathan D. Cooper
Pulmonary veno-occlusive disease (PVOD) is a rare and severe subtype of pulmonary arterial hypertension, characterized by progressive remodeling of small pulmonary arteries and veins with no therapies. Using a mitomycin C (MMC)-induced rat model, we previously demonstrated that protein kinase R (PKR)-mediated integrated stress response (ISR) drives endothelial dysfunction and vascular remodeling. To determine if PKR is the primary mediator of ISR and the pathogenesis, we treated control (Ctrl) and PKR knockout (KO) mice with the same dose of MMC. Consistent with rat data, Ctrl mice displayed ISR activation, vascular remodeling, and pulmonary hypertension after MMC treatment, while KO mice showed none of these phenotypes. Proteomic analysis revealed that MMC-mediated ISR activation attenuates protein synthesis in Ctrl but not in KO mice. These findings underscore the critical role of PKR-dependent ISR activation and subsequent perturbation of proteostasis as central mechanisms driving PVOD pathogenesis and identifying PKR as a promising therapeutic target.
Amit Prabhakar, Rahul Kumar, Meetu Wadhwa, Abhilash Barpanda, Joseph Lyons, Asavari S. Gowda, Simren P. Gupta, Ananyaa Arvind, Prajakta Ghatpande, Arun P. Wiita, Brian B. Graham, Giorgio Lagna, Akiko Hata
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.
Mackenzie L. Davenport, Amaya Fong, Gloria Montoya-Vazquez, Maria Fernanda Alves de Moura, Jodi L. Bubenik, Maurice S. Swanson
Joshua A. Keefe, Jose Alberto Navarro-Garcia, Shuai Zhao, Mihail G. Chelu, Xander H.T. Wehrens
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.
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