Development
Abstract
Skraban-Deardorff syndrome, a rare neurodevelopmental disorder caused by WD repeat domain 26 (WDR26) haploinsufficiency, is characterized by intellectual disability, seizures, autistic-like behaviors, and craniofacial anomalies. Despite its genetic association with variants disrupting the C-terminal to LisH (CTLH) E3 ubiquitin ligase complex, the molecular mechanisms linking WDR26 dysfunction to neurodevelopmental deficits remain unclear. Here, we demonstrate that Wdr26 heterozygous-KO mice (Wdr26+/–) recapitulated core clinical features of the syndrome, including learning and memory impairments, social dysfunction, heightened seizure susceptibility, and motor deficits, alongside rare craniofacial and dental abnormalities. Mechanistically, Wdr26 haploinsufficiency stabilized RUNX1 translocation partner 1 (RUNX1T1), a transcriptional coactivator critical for neuronal differentiation, by impairing its ubiquitination and proteasomal degradation, consequently disrupting the level of microtubule-associated protein 2 (MAP2), a key regulator of dendritic architecture and synaptic plasticity. Early intervention in neonatal Wdr26+/– mice (P0.5) using AAV-shRNA–mediated Runx1t1 knockdown reversed MAP2 overexpression and behavioral deficits. Notably, the antipsychotic risperidone ameliorated cognitive and social impairments in Wdr26+/– mice by upregulating WDR26 levels, suggesting a potential therapeutic avenue. Our findings not only establish the animal model as a robust preclinical tool but also define the WDR26/RUNX1T1/MAP2 regulatory axis as pivotal to the syndrome’s pathogenesis, while identifying actionable therapeutic targets.
Authors
Xingyun Xu, Yaohui Zhou, Shiyao Xu, Hongjie Zhou, Xuexia Lin, Yuhao Luo, Yu Xu, Zhigang Miao, Wei Ge, Hao Yang, Xingshun Xu
Abstract
The human epidermal growth factor receptor 2 (HER2) is a major therapeutic target in cancer. While the oncogenic effects of HER2 hyperactivation are well-characterized, the biological consequences of its deficiency remain poorly defined. Here, through exome sequencing analyses of a cohort of 720 families affected by isolated or syndromic orofacial clefts, we unexpectedly identified five distinct rare germline HER2 variants in five unrelated families with growth deficits, orofacial clefts, and other craniofacial, skeletal, and auditory anomalies. In Xenopus embryos, these variants failed to recapitulate the developmental effects of wild-type HER2. In cultured cells, they disrupted HER2 protein stability, membrane localization, or site-specific phosphorylation, resulting in diminished ERK signaling. Strikingly, knock-in mice expressing a patient-derived HER2 variant and mice maternally exposed to Tucatinib, a recently approved anti-HER2 drug, both replicated patient phenotypes: retarded growth and diverse craniofacial abnormalities, including ocular dysgenesis, short jaws, and cleft palate. Collectively, our findings define a developmental disorder that we designate GRACE syndrome (Growth Retardation and Craniofacial Malformations Caused by HER2 Deficiency), establish HER2’s essential role in human growth and craniofacial morphogenesis, and reveal that HER2-targeted therapies during pregnancy can induce craniofacial defects and lifelong growth impairment in fetuses. 5
Authors
Huaxiang Zhao, Pan Wang, Yuhua Jiao, Huimei Huang, Min Yu, Qing He, Chengkai Pan, Shuang Guo, Wenbin Huang, Yunfei Jia, Qianying Kong, Huifang Peng, Yandong Han, Yuxia Hou, Zhanping Ren, Yongwei Tao, Fei Huang, Hongwei Jiang, Shan Sun, Yanying Dong, Jiuxiang Lin, Chunyan Yin, Xuechen Zhu, Feng Chen, Yi Ding
Abstract
High levels of L- and D-2-hydroxyglutarate (2HG), the reduced forms of α-ketoglutarate (αKG), are implicated in neurodevelopmental disorders and cancer by modulating αKG-dependent dioxygenases involved in histone, DNA and RNA demethylation. L-2HG dehydrogenase (L2HGDH) deficiency, a rare autosomal recessive inborn error of metabolism associated with systemic L-2HG elevation, causes progressive neurological disability and increased brain tumor risk of unclear mechanism. Using an isogenic, patient-derived induced pluripotent stem cell (iPSC) system, we examined the impact of L2HGDH deficiency on neural progenitor cell (NPC) function and neuronal differentiation. L2HGDH deficiency caused L-2HG accumulation, NPC hyperproliferation, increased clonogenicity, and defective neuronal differentiation in 2D cultures and cortical spheroids. Editing the L2HGDH locus to wild-type reversed these effects. Inhibiting glutaminase reduced L-2HG levels and induced neuronal differentiation. L-2HG-dependent inhibition of KDM5 histone demethylases led to widespread retention of H3K4me2/3, markers of active gene expression, with prominent enrichment at the MYC locus and elevated MYC expression across multiple neural cell types. Despite broadly altered histone methylation, genetically or pharmacologically normalizing MYC completely restored neuronal differentiation. These data indicated that a primary metabolic disturbance activated MYC to favor self-renewal and suppress neuronal lineage commitment.
Authors
Wen Gu, Xun Wang, Ashley Solmonson, Ling Cai, Yi Xiao, Alpaslan Tasdogan, Jordan Franklin, Yuannyu Zhang, Hua Zhang, Aundrea K. Westfall, Ashley Rowe, Hetali Trivedi, Brandon Faubert, Zheng Wu, Jessica Sudderth, Lauren G. Zacharias, Bushra Afroze, Ilya Bezprozvanny, Sunil Sudarshan, Feng Cai, Samuel K. McBrayer, Thomas P. Mathews, Ralph J. DeBerardinis
Abstract
Neonatal life is marked by rapid antigen exposure, necessitating establishment of peripheral immune tolerance via conversion of naïve CD4+ T cells into regulatory T cells (Tregs). Here, we demonstrated heightened capacity for FOXP3 expression and tolerogenic function among cord blood versus adult blood naive CD4+ T cells and showed that this is linked to their unique metabolic profile and elevated expression of the NADase, CD38. Early-life naïve CD4+ T cells demonstrated a metabolic preference for glycolysis, which directly facilitated their differentiation trajectory. We revealed an age-dependent gradient in CD38 levels on naïve CD4+ T cells and showed that high CD38 expression contributes to both the glycolytic state and tolerogenic potential of neonatal CD4+ T cells, effects that were mediated at least in part via the NAD-dependent deacetylase SIRT1. Thus, the early-life window for peripheral tolerance in humans is critically enabled by the immunometabolic state of the naïve CD4+ compartment.
Authors
Laura R. Dwyer, Andrea M. DeRogatis, Sean Clancy, Victoire Gouirand, Charles Chien, Elizabeth E. Rogers, Scott P. Oltman, Laura L. Jelliffe-Pawlowski, Theo van den Broek, Femke van Wijk, Susan V. Lynch, Rachel L. Rutishauser, Allon Wagner, Alexis J. Combes, Tiffany C. Scharschmidt
Abstract
Germline loss-of-function folliculin (FLCN) gene mutations cause Birt-Hogg-Dubé (BHD) syndrome, in which pulmonary cysts are present in up to 90% of the patients. The pathogenic mechanisms underlying lung cyst development in BHD are almost entirely unknown because of the limited availability of BHD patient lung samples and the lack of authentic BHD lung disease models. We generated lung mesenchyme–specific and lung epithelium–specific Flcn-knockout mice using a Cre/loxP approach. We found that deletion of Flcn in lung mesenchymal cells, but not in lung epithelial cells, resulted in alveolar enlargement starting from early postnatal life, with evidence of cyst formation in adult mice, resembling the pulmonary disease in human BHD. These changes were associated with increased mechanistic target of rapamycin complex 1 (mTORC1) activity in the lungs of both patients with BHD and Flcn-knockout mice. Attenuation of mTORC1 activity by knocking out Raptor gene (Rptor) or pharmacologic inhibition using rapamycin substantially rescued the pulmonary pathology caused by Flcn deletion in mice. Taken together, these human and mouse data support a model in which mTORC1 hyperactivation drives pulmonary cystic pathology in BHD.
Authors
Ke Cao, Hui Chen, Ling Chu, Hong-Jun Wang, Jianhua Zhang, Yongfeng Luo, Joanne Chiu, Damir Khabibullin, Nicola Alesi, Matthew E. Thornton, Brendan H. Grubbs, Ali Ataya, Nishant Gupta, Francis X. McCormack, Kathryn A. Wikenheiser-Brokamp, Elizabeth P. Henske, Wei Shi
Abstract
Muscle cell fusion is critical for the formation and maintenance of multinucleated myotubes during skeletal muscle development and regeneration. However, the molecular mechanisms directing cell-cell fusion are not fully understood. Here, we identified platelet-derived growth factor receptor β (PDGFRβ) signaling as a key modulator of myocyte function in adult muscle cells. Our findings demonstrated that genetic deletion of Pdgfrb enhanced muscle regeneration and increased myofiber size, whereas Pdgfrb activation impaired muscle repair. Inhibition of PDGFRβ activity promoted myonuclear accretion in both mouse and human myotubes, whereas PDGFRβ activation stalled myotube development by preventing cell spreading to limit fusion potential. Furthermore, PDGFRβ activity cooperated with TGF-β signaling to regulate myocyte size and fusion. Mechanistically, PDGFRβ signaling required STAT1 activation, and blocking STAT1 phosphorylation enhanced myofiber repair and size during regeneration. Collectively, PDGFRβ signaling acts as a regenerative checkpoint and represents a potential clinical target to improve skeletal muscle repair.
Authors
Siwen Xue, Abigail M. Benvie, Jamie E. Blum, Benjamin D. Cosgrove, Anna E. Thalacker-Mercer, Daniel C. Berry
Abstract
Alternative splicing-triggered nonsense-mediated mRNA decay (AS-NMD) critically regulates gene expression, but the extent to which neuronal genes are regulated by AS-NMD remains understudied. Here, we identified more than 3,000 developmentally regulated AS-NMD exons in mouse and human brains, and validated them in cultured neurons. AS-NMD suppresses synaptic genes during brain development and differentially regulates more than 200 causal genes for neurodevelopmental disorders (NDDs). We detected an AS-NMD exon in GRIA2 and identified splice-switching antisense oligonucleotides that suppressed GRIA2 NMD and increased its functional isoforms. In summary, this study uncovers genes repressed by AS-NMD in the brain and nominates amenable splice-switching targets for treating dominant NDDs such as autism spectrum disorders and developmental epileptic encephalopathy.
Authors
Kaining Hu, Runwei Yang, Jiaming Qiu, Xinran Feng, Kayleigh J. LaPre, Jessica Tanouye, Yalan Yang, Xiaochang Zhang
Abstract
How β-Catenin (βCat) mediates tissue hyperplasia is poorly understood. To explore this, we employed the adrenal cortex as a model system given its stereotypical spatial organization and the important role βCat plays in homeostasis and disease. For example, excessive production of aldosterone by the adrenal cortex (primary aldosteronism, PA) constitutes a major cause of cardiovascular morbidity and is associated with βCat gain-of-function (βCat-GOF). Adherens junctions (AJs) connect the actin cytoskeletons of adjacent zona Glomerulosa (zG) cells via a cadherin-βCat-α-Catenin complex and mediate aldosterone production. Whether βCat-GOF drives zG hyperplasia, a key feature of PA, via AJs is unknown. Here, we showed that aldosterone secretagogues (K+, AngII) and βCat-GOF mediated AJ formation via Rho/ROCK/actomyosin signaling. In addition, Rho/ROCK inhibition led to altered zG rosette morphology and decreased aldosterone production. Mice with zG-specific βCat-GOF demonstrated increased AJ formation and zG hyperplasia, which was blunted by Rho/ROCK inhibition and deletion of α-Catenin. βCat also impacted AJ formation independently of its role as a transcription factor. Furthermore, analysis of human aldosterone-producing adenomas revealed high levels of βCat expression were associated with increased membranous expression of K-Cadherin. Together, our findings identified Rho/ROCK signaling and αCat as key mediators of AJ formation and βCat-driven hyperplasia.
Authors
Mesut Berber, Betul Haykir, Nick A. Guagliardo, Vasileios Chortis, Kleiton Silva Borges, Paula Q. Barrett, Felix Beuschlein, Diana L. Carlone, David T. Breault
Abstract
The lymphatic system maintains tissue fluid balance, and FOXC2 mutations cause lymphoedema-distichiasis syndrome, which is characterized by lymphatic valve defects. Although oscillatory shear stress regulates FOXC2 expression, other extracellular regulators remain unclear. In this study, we identified LPA4 and LPA6, two Gα12/Gα13-coupled receptors for the bioactive lipid lysophosphatidic acid (LPA), as key regulators of FOXC2 expression and lymphatic valve development. Lymphatic endothelial cell (LEC)-specific Lpa4;Lpa6-deficient mice exhibited impaired lymphatic valve formation and maintenance, which resembled phenotypes of LEC-specific Foxc2-deficient mice, including abnormal lymphatic vessel patterning. Mechanistically, lymphatic endothelial Lpa4/Lpa6 ablation reduced FOXC2 expression in vitro and in vivo. NF-κB was found essential for LPA-induced FOXC2 expression through the LPA4/LPA6-Gα12/Gα13-Rho kinase signaling axis. Accordingly, pharmacological inhibition of NF-κB and Rho kinase impaired lymphatic valve maintenance in mice. These results suggested that lymphatic endothelial LPA4 and LPA6 synergistically regulate FOXC2 expression through NF-κB activation and play an important role in lymphatic valve formation and maintenance. Our findings provide a molecular basis for lymphatic vessel development with a therapeutic potential for targeting lymphatic-associated diseases.
Authors
Daisuke Yasuda, Nana Sato, Keisuke Yanagida, Tomomi Hashidate-Yoshida, Tomohiro Shiiya, Hideo Shindou, Atsuki Taira, Takashi Ebihara, Takao Shimizu, Masanori Hirashima, Seiya Mizuno, Satoru Takahashi, Satoshi Ishii
Abstract
Lymphatics maintains fluid homeostasis, immune surveillance, and tissue integrity. Here, we identified the E26 transformation-specific (ETS) transcription factors Erg and Fli1 as essential, cooperative regulators of lymphatic integrity and function. Using inducible, lymphatic endothelial cell-specific deletion in mice, we demonstrated that combined loss of Erg and Fli1 in adults results in fatal lymphatic failure, including chylothorax, chylous ascites, and impaired lymphatic drainage. Single-cell transcriptomic analysis revealed that loss of Erg and Fli1 caused disrupted lymphatic heterogeneity and dysregulation of key lymphatic genes, including valve-specific gene profiles. Erg and Fli1 coordinated lymphatic-immune crosstalk by transcriptionally regulating C-C motif chemokine ligand 21 (Ccl21), which mediates dendritic cell trafficking. Their loss also induced pro-inflammatory and pro-thrombotic gene expression, further contributing to lymphatic dysfunction. During embryonic development, the co-deletion led to lymphatic mis-patterning and loss of valve-initiating lymphatic endothelial cell clusters. The impact of loss of Erg and Fli1 function on lymphatic development in mice is consistent with FOXC2 mutations in lymphedema-distichiasis syndrome or ERG gene variants underlying primary lymphoedema in humans. Moreover, Erg and Fli1 were required for regenerative lymphangiogenesis and lymphatic repair following injury in adults. Our findings establish Erg and Fli1 as core transcriptional regulators of lymphatic identity, integrity, and function.
Authors
Myung Jin Yang, Seok Kang, Seon Pyo Hong, Hokyung Jin, Jin-Hui Yoon, Cheolhwa Jin, Chae Min Yuk, Lidiya G Gebeyehu, Junho Jung, Sung-hwan Yoon, Hyuek jong Lee, Gou Young Koh
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Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)