Development
Abstract
Authors
Diana B. Voss, Emily J. Shields, Andrey Poleshko, Li Li, Jun Li, Roger Wang, Mariacristina Calcagno, Rajan Jain, Cheryl L. Smith, Jonathan A. Epstein
Abstract
Epilepsy affects approximately 50 million people worldwide, yet more than half of individuals with a presumed genetic cause still lack a molecular diagnosis despite the identification of over 1,000 monogenic epilepsy genes. This diagnostic gap is unlikely to be resolved by improved variant detection alone, suggesting that variants affecting the same biological pathway may combine to cause disease. By studying epilepsy-associated actin regulatory genes, we identified a conserved “actin-mitochondria-glutamate (AMG) pathway”. We demonstrate that reduced actin polymerization promotes DRP1-mediated mitochondrial fission, increases reactive oxygen species (ROS) levels, and enhances glutamatergic transmission, leading to seizures. The glial innate immune pathway, a recently recognized contributor to epilepsy, is activated when the AMG pathway is affected. Reducing mitochondrial fission with the DRP1 inhibitor Mdivi-1, or suppressing ROS with N-acetyl-L-cysteine amide (NACA), significantly alleviates seizures. Importantly, digenic heterozygous loss‑of‑function variants in AMG‑pathway genes combine to cause seizures, and individuals with epilepsy of unknown etiology show an increased burden of such variants when compared to the controls. Modeling patient‑specific digenic combinations in Drosophila confirms that many combinations promote seizure susceptibility. Together, these findings establish the AMG pathway as a mechanistic framework for identifying digenic etiologies in epilepsy and highlight potential therapeutic targets.
Authors
Shenzhao Lu, Mengqi Ma, Shabab B. Hannan, Mingxi Deng, Hu Chen, Zhijian Yu, Lindsey D. Goodman, Haein Kim, Yun Zhao, Sandeep Kumar Dubey, Wen-Wen Lin, Xueyang Pan, Debdeep Dutta, Vishnu Anand Cuddapah, Jill A. Rosenfeld, Xi Luo, Zhandong Liu, Joshua M. Shulman, Hugo J. Bellen
Abstract
Kleefstra syndrome (KLEFS1) results from EHMT1 haploinsufficiency and is characterized by variable neurodevelopmental delays and psychopathology. Developmental regression, marked by the sudden loss of previously acquired daily life skills during late puberty or early adulthood, has emerged as a severe complication in individuals with KLEFS1. To investigate the clinical and molecular mechanisms underlying developmental regression and assess the therapeutic potential of olanzapine, we conducted a sequential study in an international cohort of fifty-four individuals with KLEFS1. Among sixteen individuals treated with olanzapine, ten exhibited a beneficial response based upon improvement of their adaptive functioning, and four showed temporary improvement. These clinical findings informed preclinical studies using human induced pluripotent stem cell-derived and ex-vivo cortical slices from a mouse model of KLEFS1. We identified hyperactivity in EHMT1+/– neuronal networks co-cultured with EHMT1+/– astrocytes, a dysfunction reversible by olanzapine. Mechanistically, EHMT1+/– astrocytes displayed elevated levels of S100B, a neuroinflammatory marker contributing to neuronal network hyperactivity. Notably, olanzapine treatment reduced S100B levels, and pharmacological inhibition or genetic knockdown of S100B in EHMT1+/– astrocytes was sufficient to rescue the neuronal hyperactivity phenotype. These findings underscore a critical role for astrocytes in KLEFS1 pathophysiology and identify a potential cellular target for olanzapine in mitigating developmental regression.
Authors
Karlijn Vermeulen-Kalk, Shan Wang, Joost Kummeling, Britt Mossink, Kim N. Wijnant, Carlos O. González Jiménez, Zoe J. Frazier, Brian J. Rozumny, Anne O'Donnell-Luria, Ellen Hanson, Monica Frega, Katrin Linda, Moritz Negwer, Bas Lendemeijer, Astrid Oudakker, Monica Pop-Purceleanu, Joost G.E. Janzing, Linde van Dongen, Femke M.S. de Vrij, Steven A. Kushner, Ilse van der Werf, Chantal Schoenmaker, Wouter Oomens, Siddharth Srivastava, Jos I.M. Egger, Hans van Bokhoven, Dirk Schubert, Nael Nadif Kasri, Tjitske Kleefstra
Abstract
Reproductive aging is characterized by a progressive decline of reproductive function, with broad implications for overall health and longevity. Environmental factors, including assisted reproductive technologies (ART), can accelerate reproductive aging by promoting premature ovarian failure in females. In vitro fertilization (IVF) though widely used and generally considered safe, has been associated with lasting effects on offspring health. Using a mouse model that closely approximates human IVF, we demonstrated that IVF accelerates reproductive aging in female offspring by inducing premature ovarian failure. IVF-conceived females exhibited altered ovarian function, reduced follicle reserve, disrupted endocrine profiles, and transcriptomic and epigenetic changes consistent with premature reproductive decline. These findings reveal long-term consequences of IVF on female reproductive health and highlight the need to understand how early-life interventions influence reproductive longevity.
Authors
Eric A. Rhon-Calderon, Cassidy N. Hemphill, Alexandra J. Savage, Ana Domingo-Muelas, Zhengfeng Liu, Christopher J. Krapp, Laren Riesche, Nicolas Plachta, Richard M. Schultz, Marisa S. Bartolomei
Abstract
Gene therapy-based biological pacemakers have been proposed as an alternative to their hardware-based counterparts. In this context, short-term ectopic expression of the T-box transcription factor 18 (TBX18) in the ventricle has been reported to generate potent short-term pacemaker function in various animal models. Here, we investigated the impact of adeno-associated virus (AAV)-mediated long-term expression of TBX18, and compared the outcomes to those of the pacemaker ion channel Hcn2. Our findings revealed that CMV-driven ectopic TBX18 expression in mouse hearts led to severe cardiac fibrosis. At lower, non-fibrogenic levels, TBX18 maintained its transcriptional function but failed to induce pacemaker phenotypes. TBX18-expressing cells showed suppressed expression of key working myocardial genes, but the pacemaker gene program was not induced. Electrophysiological studies showed abnormal automaticity in TBX18-expressing cells, combined with prolonged repolarization and various current changes. However, no hyperpolarization-activated funny current was detected. In a complete AV-block rat model, AAV-mediated Hcn2 expression induced robust ectopic pacemaker activity in the presence of isoproterenol, whereas TBX18 expression neither generated such activity nor augmented Hcn2-mediated pacing. In conclusion, at functionally non-fibrogenic levels, TBX18 is neither sufficient nor necessary to induce pacemaker activity. In contrast, Hcn2 generates reliable pacing, making it a more viable candidate for biological pacemaker development.
Authors
Jianan Wang, Mathilde R. Rivaud, Mischa Klerk, Arie R. Boender, Ruud N. Visser, Rinske Sparrius, Hee Young Lee, Karel van Duijvenboden, Huiling Zhou, Yuting Yang, Emiel J.M. Kramer, Kyung Ho Park, Larry C. Park, Silke Schrödel, Christian Thirion, Eric Ehrke-Schulz, Anja Ehrhardt, Osne F. Kirzner, Klaus Neef, Hanno L. Tan, Arie O. Verkerk, Vincent M. Christoffels, Gerard J.J. Boink
Abstract
De novo heterozygous variants in CELF2 have recently been associated with a rare neurodevelopmental disorder, yet the mechanisms linking specific variants to distinct clinical phenotypes remain poorly understood. Here, we reported a cohort of 18 individuals and provided evidence that variants causing CELF2 mislocalization, but not protein-null variants, were associated with seizures. Using proband-derived human cortical neurons and transgenic mouse models, we demonstrated that CELF2 underwent activity-dependent nucleocytoplasmic shuttling in excitatory neurons and that its cytoplasmic retention caused neuronal hyperactivity, elevated seizure susceptibility, and learning and memory deficits. We further found that cytoplasmic CELF2 regulated mRNAs critical for synaptic function and neuronal excitability and implicated in epileptic seizures and intellectual disability. Drug screening further identified AKT signaling as a key regulator of CELF2 nucleocytoplasmic shuttling and a candidate target for reversing neuronal hyperactivity. Together, our findings expand the clinical and genetic spectrum of CELF2-related neurodevelopmental disorders and establish a variant-specific mechanism that links CELF2 mislocalization to neuronal hyperactivity, seizures, and cognitive impairment.
Authors
Michelle Hua, Mohamad-Reza Aghanoori, Melissa J. MacPherson, Yi Ren, Shehani V. Siripala, Yifan Yang, Yvonne Yan Yan Or, Malea Nguyen, Robert Duba-Kiss, Daniel Feng, Laura Williams, Christopher J. Gafuik, GengYi Wang, Chloe Quelin, Boris Keren, Sarah Schuhmann, Georgia Vasileiou, Alexia Bourgois, Antonio Vitobello, Christophe Philippe, Zornitza Stark, Richard J. Leventer, George McGillivray, Frederic Tran Mau-Them, Marine Tessarech, Clément Prouteau, Phillis Lakeman, Mahdi M. Motazacker, Donald R. Latner, Raymond C. Caylor, Yvette van Ierland, Eloise Prijoles, Angie Lichty, Evangelos Theodorou, David A. Sweetser, Edward Steel, Jan Cobben, Majed J. Dasouki, Daniel G. Calame, Bertrand Isidor, Benjamin Cogné, Mitchell Kesler, Brooke Rackel, Isabel Clark, Deborah M. Kurrasch, G. Campbell Teskey, James Ellis, Guiqiong He, Scott D. Ryan, Douglas J. Mahoney, A. Micheil Innes, Jonathan R. Epp, Guang Yang
Abstract
Chromatin remodeling is a dynamic epigenetic process that alters chromatin structure to gauge gene accessibility, enabling precise spatiotemporal gene expression, with disruptions often underlying neurodevelopmental disorders (NDDs), although the mechanistic underpinning remains incompletely understood. Despite essential roles in chromatin remodeling processes such as DNA methylation, and histone acetylation and deposition, DMAP1 has not been implicated in human disease. We identified 20 individuals from 16 families with a syndromic NDD carrying homozygous or compound heterozygous variants in DMAP1. Neural-specific knockdown of its Drosophila ortholog, dDMAP1, caused pupal lethality, structural defects in the mushroom body (MB), decreased dendrite length, abnormal social behavior and mechanical-induced seizures. Human reference DMAP1 could largely compensate for the loss of dDMAP1 in knockdown flies, whereas patient variants failed to restore or differentially rescued the phenotypes, confirming their pathogenicity with differing severity. Transcriptome profiling of dDMAP1 knockdown fly brains nominated Cbl and SF1 as downstream targets. Their overexpression rescued the aforementioned lethality and MB defects. Finally, a DNA methylation episignature was identified, leading to the molecular diagnosis of an additional patient. Our findings demonstrate that biallelic inactivating variants in DMAP1 cause a syndromic NDD, expanding the short list of recessive disease-causing genes within the epigenetic machinery.
Authors
Qin Wang, Andrew K. Sobering, Christian Tirrito, Sadegheh Haghshenas, Tina Duelund Hjortshøj, Konrad Platzer, Silke Redler, Michael E. March, Leticia S. Matsuoka, Hang Xi, Josiah Zoodsma, Yuanhua Chen, Mari Mori, Marco L. Leung, Nathalie Couque, Alain Verloes, Antoine Pouzet, Noor A.A. Giesbertz, Marleen E.H. Simon, Ashley K. Yearwood, Dominique L. Assing, Tzung-Chien Hsieh, Jing-Mei Li, Michael A. Levy, Jennifer Kerkhof, Haley McConkey, Jessica Rzasa, Carolyn Lauzon-Young, Raashda A. Sulaiman, Firdous Abdulwahab, Hanan E. Shamseldin, Naif A.M. Almontashiri, Manal Afqi, Vettaikorumakankav Vedanarayanan, Maria J. Guillen Sacoto, Ingrid M. Wentzensen, Nadirah S. Damseh, Rivka Birnbaum, Babeth van Ommeren, Saskia M.J. Hopman, Maha S. Zaki, Gehad Elmakkawy, Erum Afzal, JiHye Kim, Stephanie Efthymiou, Henry Houlden, Ambreen Nusrat, Mathias Toft, Uzma Abdullah, Zafar Iqbal, Shannon Terek, Fowzan S. Alkuraya, Elizabeth J. Bhoj, Reza Maroofian, Bekim Sadikovic, Hakon Hakonarson, Yuanquan Song, Dong Li
Abstract
Enhanced TGFβ signaling caused by mutations in Fibrillin-1 (FBN1) in patients with Marfan syndrome (MFS) leads to myxomatous degeneration of the mitral valve (MDMV). MDMV can result in mitral valve prolapse, severe regurgitation, and sudden cardiac death. However, it remains unknown whether lymphatic vessel (LV) dysfunction contributes to MDMV development in MFS. Here, we show that lymphangiogenesis in murine mitral valves (MVs) begins postnatally. However, this process is inhibited in a mouse MFS model, Fbn1 mutant (Fbn1C1039G/+) mice, accompanied by disrupted lymphatic cell-cell junctions, impaired lymphatic drainage, and an abnormally widespread distribution of MHCII+ infiltrating macrophages. Treatment of Fbn1 mutant mice with VEGF-C156S, a selective VEGFR3 agonist, stimulates the ERK and Akt pathways, increases LV density in MVs, and ameliorates MDMV. Fbn1 mutant MVs display disorganized valvular endothelial cells (VECs) and decreased expression of the anti-inflammatory modulator Zfp36 (zinc finger protein 36) in VECs and immune cells. Treatment with FTY720 (Fingolimod), a ZFP36 activator and S1P antagonist, rescues MDMV phenotypes in Fbn1 mutant mice by reducing immune cell infiltration and restoring lymphatic cell junctions and drainage. These findings suggest that the Fbn1 mutation causes LV hypoplasia and defective lymphatic drainage in MVs, driven in part by pro-inflammatory VECs, leading to MFS-related MDMV.
Authors
Can Tan, Ziyou Ren, Shreya Kurup, Xianpeng Liu, Zhi-Dong Ge, Shodai Suzuki, Pritika Jakka, Cheryl Tang, M. Luisa Iruela-Arispe, Tsutomu Kume
Abstract
Cancers reflect aberrant growth and differentiation of normal cell populations. Biological understanding of small intestine neuroendocrine tumors (SI-NETs) is hampered because their closest normal counterparts, enteroendocrine cells (EECs), constitute tiny fractions of intestinal epithelium. Recent characterization of adult human EEC ontogeny from intestinal stem cells can help overcome that limitation. Transient expression of transcription factor gene ASCL1 normally ensures proper timing and fidelity of well-differentiated EECs, which express NEUROD1. Here we report that SI-NETs resembled mature enterochromaffin cells; however, individual tumor cells co-expressed stem/progenitor genes, harboring each differentiation state along the EEC trajectory except ASCL1+ precursors. We found that enhancers normally active, and others inactive, during EEC differentiation underlie aberrant SI-NET gene activity. SI-NETs uniformly expressed NEUROD1 but lacked ASCL1, owing to inaccessible chromatin and repressive H3K27me3 marking at the ASCL1 locus. Multiple cyclin-dependent kinase inhibitor (CDKi) genes were similarly silenced, other than CDKN1B, the only gene recurrently mutated in SI-NETs. Deletion of CDKN1B altered cell cycle kinetics during human EEC differentiation, and deletions of ASCL1 or CDKN1B activated certain genes that are expressed in SI-NETs but not in the normal EEC trajectory. We propose that a limited CDKi repertoire and absence of ASCL1-dependent constraints on EEC maturation together explain unique SI-NET characteristics.
Authors
Pratik N.P. Singh, Elsa Hadj Bachir, James R. Howe, Andrew M. Bellizzi, Paloma Cejas, Shariq Madha-Krause, Charles B. Epstein, Jennifer Chan, Bradley E. Bernstein, Matthew H. Kulke, Qiao Zhou, Ramesh A. Shivdasani
Abstract
We previously identified a muscular dystrophy caused by biallelic variants in JAG2, whose protein product Jagged2 JAGGED2 (JAG2) is a canonical Notch NOTCH ligand. However, the disease mechanism remains unclear, particularly with respect to muscle stem cell (MuSC) function and muscle regeneration. We examined the consequences of JAG2 deficiency and modeled pathogenic JAG2 variants in vitro and in vivo, the latter in mouse and fly models and with particular attention to the MuSC-muscle endothelial cell (MuEC) niche. We found that both Jag2 deficiency and overexpression of pathogenic JAG2 variants impaired NOTCHNotch signaling and myogenic self-renewal and differentiation. Hypomorphic Jag2 mutant (Jag2sm) mice display depleted MuSCs, corresponding with impaired muscle regeneration in those mice. Co-culture experiments and the examination of cell-type-specific Jag2 conditional knockout mice demonstrated that MuEC-specific Jag2 knockout resulted in reduced MuSC self-renewal, while MuSC-specific Jag2 knockout resulted in reduced myogenic differentiation. Human reference JAG2, but not human pathogenic variants of JAG2, rescued the deficiency of Serrate (Ser), the Drosophila ortholog of JAG2. Therefore, pathogenic variants in JAG2 impair muscle development and regeneration through disrupted cell-autonomous cis-inhibition and non-autonomous trans-activation involving NOTCHNotch signaling dysfunction. Our findings indicate that optimizing JAG2-mediated NOTCHNotch signaling is a potential therapeutic approach for JAG2-related muscular dystrophy.
Authors
Minoru Tanaka, Nam Chul Kim, Isabelle Draper, Hannah R. Littel, Mekala Gunasekaran, Johnnie Turner, Natalya M. Wells, Qasim Mujteba, Yoko Asakura, Peter B. Kang, Atsushi Asakura
No posts were found with this tag.
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)