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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
Neuropathic pain affects over 20 million people in the United States, and painful diabetic neuropathy (PDN), a common complication of diabetes, is among its most prevalent and treatment-resistant forms. Although PDN is characterized by nociceptor dysfunction, the upstream peripheral mechanisms remain incompletely understood. While dorsal root ganglion (DRG) nociceptor hyperexcitability is a hallmark of PDN, emerging evidence suggests that non-neuronal skin cells may modulate nociceptor function. Here, we investigated whether epidermal Langerhans cells (LCs) contribute to neuropathic pain in PDN through neuroimmune signaling. Using a clinically relevant high-fat diet (HFD) mouse model, transgenic LC ablation, behavioral assays, human skin biopsies, and single-cell RNA sequencing of epidermis and DRG, we found that LC density increased in male diabetic mice in parallel with mechanical allodynia. In human PDN skin, LCs exhibited increased volume and dendritic complexity correlating with diabetes duration. Genetic depletion of LCs prevented mechanical allodynia and spontaneous pain-like behavior in male, but not female, HFD mice, revealing a sex-dependent contribution. Single-cell and interactome analyses identified male-specific inflammatory LC programs, including upregulation of chemokine signaling pathways. Consistently, LC secretome profiling showed increased CCL2 release, and local CCR2 blockade reversed allodynia. These findings identify epidermal LCs as peripheral regulators of PDN pain and highlight sex-dependent chemokine-mediated neuron-immune communication at the skin-nerve interface.
Authors
Paola Pacifico, Dale George, Nirupa D. Jayaraj, Dongjun Ren, James S. Coy-Dibley, Abdelhak A. Belmadani, Sofia Veronesi, Mirna Andelic, Daniele Cartelli, Grazia Devigili, Raffaella Lombardi, Giuseppe Lauria Pinter, Amy S. Paller, Richard J. Miller, Daniela Menichella
Abstract
BACKGROUND. Anti-nephrin autoantibodies have emerged as a putative pathogenic driver in a subset of patients with podocytopathies, including those with post-transplant disease recurrence. METHODS. We measured anti-nephrin autoantibodies in a cohort of 65 patients with podocytopathy associated with steroid-sensitive nephrotic syndrome (n = 39) and steroid-resistant nephrotic syndrome (n = 26), and in 34 patients with post-transplant podocytopathy recurrence. Fourteen patients with membranous nephropathy and 20 healthy volunteers served as controls. ELISA and immunoprecipitation assays were performed to detect anti-nephrin IgG using two different recombinant human nephrin proteins. Immunofluorescence analysis was performed to assess the deposition of IgG and their colocalization with nephrin in renal biopsies. RESULTS. When using murine antigen-based ELISA, the highest positivity was found in healthy volunteers (55%), correlating with levels of circulating natural anti-α-galactose-α-1,3-galactose antibodies. This cross-reactivity was abrogated with recombinant human nephrin expressed in human cells. In this setting, very low prevalence (<5%) of anti-nephrin antibody-positive patients was found in steroid-sensitive and steroid-resistant nephrotic syndrome cohorts and in patients with post-transplant disease recurrence. These frequencies were comparable to healthy volunteers. Using confocal and super-resolution microscopy, only trace amounts of IgM, but no IgG, were found in the glomeruli of analyzed biopsies, which did not colocalize with nephrin. CONCLUSIONS. With the methodology presented here, anti-nephrin reactivity was extremely rare and occurred at comparably low frequencies in healthy controls, native-kidney podocytopathies, and post-transplant disease recurrence. This suggests that these autoantibodies are not inherently disease-specific and may not serve as a broad biomarker across podocytopathies. TRIAL REGISTRATION. ClinicalTrials.gov NCT06334692. FUNDING. Private donation.
Authors
Francesco Pecoraro, Luca Perico, Federica Casiraghi, Paola Rizzo, Matias Trillini, Andrea Angeletti, Manuel Alfredo Podestà, Xhuliana Kajana, Agnese Spennacchio, Marta Todeschini, Marilena Mister, Giuseppe Castellano, Ariela Benigni, Giuseppe Remuzzi
Abstract
Iron overload has emerged as a significant risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD), a growing global health concern. Despite this association, the precise mechanisms by which hepatic iron and its regulatory genes connect liver pathology to systemic metabolic dysfunction remain elusive. Here, we demonstrate that humoral signals originating from iron-overloaded hepatocytes act as critical mediators driving systemic metabolic dysfunction in MASLD. Ferroportin (FPN, SLC40A1), the sole cellular iron exporter, exhibits markedly reduced expression in hepatocytes of both human patients and mouse models with MASLD, concomitant with hepatic iron accumulation. Functionally, hepatocyte-specific FPN deletion significantly exacerbates diet-induced obesity and insulin resistance, with these metabolic perturbations accompanied by decreased energy expenditure and impaired thermogenic capacity. Mechanistically, we establish that hepatic iron accumulation resulting from FPN deficiency enhances the production of two specific hepatokines, Fetuin-A and LECT2, through activation of the transcription factor FoxO1. Notably, therapeutic interventions — including genetic silencing of these hepatokines, hepatocyte-specific FPN overexpression, or oral iron chelation — effectively reverse the metabolic dysfunction phenotypes. These findings provide critical insights into the pathophysiological mechanisms linking MASLD to systemic metabolic disorders and highlight promising therapeutic strategies to combat these diseases.
Authors
Hye Jin Jo, Ayoung Kim, Hyunsoo Rho, Ae Kyung Park, Gil-Hwan Kim, Seo Jeong Jo, Hao Yuxin, You-Jung Hong, Ji Min Yeon, Hwang Chan Yu, Mi-Young Song, Jeongwoo Park, Yeon Hee Jeong, Sung Eun Hong, Hyo Jin Yeon, Da Young Oh, Philipp E. Scherer, Cheol Soo Choi, Dong Hyeon Lee, Sung Hwan Ki, Keon Wook Kang, Murim Choi, Byung-Hyun Park, Eun Ju Bae, Sang Geon Kim, Won Kim, Chang Yeob Han
Abstract
Coenzyme A (CoA) facilitates fatty acid synthesis, energy production, gene regulation, and antioxidant function. While CoA biosynthesis is well-characterized, the mechanisms governing CoA degradation remain poorly understood. Here, we identify the Metazoan Homolog of SpoT, MESH1, as a CoA phosphatase that dephosphorylates CoA at the 3’ position of the ribose ring to form dephospho-CoA (dp-CoA). Recent studies have shown that CoA, similar to glutathione (GSH), is a cysteine-derived metabolite that protects cells against ferroptosis. Ferroptosis induced by blocking cystine import depletes CoA biosynthesis, while CoA restoration rescues cells from ferroptosis. We found that MESH1 knockdown preserved CoA levels by preventing its degradation, contributing to ferroptosis protection, indicating the bifunctional role of MESH1 in regulating CoA and previously reported NADPH. Mechanistically, MESH1 knockdown elevates CoA levels, maintaining functional mitochondrial thioredoxin system, thereby preventing mitochondrial lipid peroxidation. In Drosophila, we found that dMesh1 overexpression leads to ferroptosis-mediated muscle atrophy, which can be rescued by increasing CoA and NADPH levels. Taken together, these findings establish MESH1 as a key phosphatase that governs ferroptosis sensitivity by coordinating CoA and NADPH homeostasis, unveiling a novel link between CoA degradation, mitochondrial integrity, and muscle health.
Authors
Chao-Chieh Lin, Joshua Rose, Alexander A. Mestre, Chien-Kuang C. Ding, Ssu-Yu Chen, Sze Mun Choy, Kah Yong Goh, Weiyi Jiang, Wen Xing Lee, Qizhou Jiang, Yanting Chen, Tianai Sun, Jianli Wu, Yueqi Chen, Yunju Oh, Pyeonghwa Jeong, Jiyong Hong, Kenon Chua, Michael C. Fitzgerald, Guo-Fang Zhang, Hong-Wen Tang, Pei Zhou, Jen-Tsan Chi
Abstract
The liver plays a critical role in lipid homeostasis, where lipids are either secreted as very-low-density lipoproteins (VLDL) or stored in lipid droplets (LDs). However, the regulatory mechanisms governing these two interconnected processes remain poorly understood. Here, we demonstrate that SEC16B functions as a lipid-responsive regulator in the liver, promoting VLDL secretion and LD expansion to handle lipid flux and maintain lipid homeostasis. Genome-wide association studies have identified single-nucleotide polymorphisms in SEC16B to be highly associated with serum lipid levels in humans. Hepatic Sec16b deficiency decreases serum lipid levels by impairing VLDL secretion through mechanisms that are at least partially independent of microsomal triglyceride transfer protein (MTP)-mediated ApoB lipidation and COPII-mediated intracellular trafficking. SEC16B partially localizes at ER-LD contact sites and promotes LD expansion by facilitating the targeting of ER proteins to LDs. More importantly, suppression of Sec16b dramatically lowers serum lipid levels and reduces atherosclerotic lesion size in Ldlr null mice. These data reveal a mechanism that coordinates VLDL and LD metabolism and suggest SEC16B as a potential therapeutic target for atherosclerosis treatment.
Authors
Wei Lu, Zhiming Zhao, Donald Molina, Huaxun Fan, Ruicheng Shi, Ye Tian, Raja Gopoju, Tiantian Yang, Xinyuan Zhang, Yanqiao Zhang, Kai Zhang, Jaume Amengual, Bo Wang
Abstract
Sphingosine-1-phosphate lyase (SPL) insufficiency syndrome (SPLIS) or nephrotic syndrome type 14 (NPHS14), is an autosomal recessive multisystem disorder caused by loss-of-function mutations in SGPL1, encoding the enzyme responsible for the terminal degradation of sphingosine-1-phosphate (S1P). We investigated a patient carrying a previously undescribed c.1084T>A (p.Ser362Thr) SGPL1 variant and analyzed the metabolic and cellular consequences of SPL deficiency using patient fibroblasts, SGPL1-knockout HEK293T cells, and Sgpl1–/– and Sgpl1rosa+fl/fl mice. Metabolic stable isotope labelling revealed that SPL deficiency does not invariably result in S1P accumulation. Instead, SPL-deficient cells maintain near-normal S1P levels through (i) feedback regulation of de novo sphingolipid synthesis via the ORMDL–ceramide axis and (ii) increased diversion of excess ceramides into glycosphingolipids. However, perturbation of sphingolipid homeostasis — either by exogenous sphingolipid load or disruption of compensatory regulation — induces pathological intracellular S1P accumulation. In vivo, Sgpl1–/– mice exhibited pronounced urinary S1P excretion and renal S1P enrichment, accompanied by cytoskeletal disorganization and impaired epithelial morphogenesis. Mechanistically, we identify aberrant Rho–ROCK signaling as a key mediator of S1P-driven cytoskeletal dysregulation. Pharmacological ROCK inhibition with Fasudil mitigated renal cytoskeletal defects in Sgpl1–/– and Sgpl1rosa+fl/fl mice and partially restored epithelial architecture. These findings redefine the metabolic consequences of SPL deficiency and identify S1P-driven Rho–ROCK hyperactivation as a tractable therapeutic target in SPLIS.
Authors
Adam Majcher, Ranjha Khan, Kathrin Buder, Florence Bourquin, Julie D. Saba, Thorsten Hornemann
Abstract
Regulatory T (Treg) cells expressing Forkhead Box P3 (FOXP3) play crucial roles in maintaining immune tolerance and tissue integrity. EZH2, a Histone H3 lysine 27 (H3K27) methyltransferase, is known as a key regulator of Treg cell identity and suppressive function upon activation. Here, we demonstrate that the H3K27 lysine demethylase KDM6B, which catalyzes the opposing reaction to EZH2, was also required for Treg cell identity and function after activation. Treg-specific deletion of Kdm6b impaired tissue Treg cell fate and function. KDM6B was upregulated following T cell antigen receptor (TCR) signaling in Treg cells and contributed to the regulation of Treg-associated gene expression through both direct and indirect mechanisms. A subset of Treg functional genes were direct targets of KDM6B and were co-occupied by FOXP3 at cis-regulatory regions, where KDM6B recruitment limited H3K27me3 accumulation. More broadly, KDM6B-dependent H3K27 demethylation facilitated Treg gene expression programs that supported tissue Treg homeostasis.
Authors
Minghong He, Beisi Xu, Pria G. Bose, Morgan J. McCullough, Rani S. Sellers, Xinying Zong, Wenjie Qi, Brianna L. Banten, Miriya K. Tune, Matthew P. Zimmerman, Genevieve N. Mullins, Brian C. Miller, J. Justin Milner, Jason K. Whitmire, Ageliki Tsagaratou, Karl B. Shpargel, Claire M. Doerschuk, Yong-Dong Wang, Jacob A. Steele, Shondra M. Pruett-Miller, Yongqiang Feng, Jason R. Mock
Abstract
Apolipoprotein B (APOB) containing lipoproteins contribute to atherosclerosis by entering the arterial wall through the endothelial cell (EC) surface receptors scavenger receptor-BI (SR-BI) and activin receptor-like kinase 1 (ALK1). We used N-terminal fragments of APOB, molecular modeling, and site-directed mutagenesis to identify and block the binding of chylomicrons and LDL to these receptors in cells and mice. We discovered that different APOB regions interact with SR-BI and ALK1 expressed on ECs APOB48 lipoproteins were only internalized by SR-BI. A fragment of APOB, comprising 18% of the N-terminal sequence, APOB18, reduced the uptake and transport of both chylomicrons and LDL by ECs, whereas a shorter fragment, APOB12, only blocked ALK1 mediated uptake of APOB100 containing lipoproteins. Importantly, overexpressing APOB18 decreased atherosclerosis in hypercholesterolemic mice. These findings identify the N-terminal region of APOB as the cause of atherosclerosis and illustrate an approach to treating or preventing vascular disease.
Authors
Ainara G. Cabodevilla, Camila Calistru, Waqas Younis, Dimitris Nasias, Tse W.W. Ho, Narasimha Anaganti, Swati Valmiki, Sujith Rajan, Jana Gjini, Rufina Kore, Carmen Hannemann, Nicholas O. Davidson, Tomas Vaisar, Jenny E. Kanter, Karin E. Bornfeldt, Edward A. Fisher, Warren L. Lee, Tobias Madl, M. Mahmood Hussain, Ira J. Goldberg
Abstract
Typ515 (W515) mutations in the protein MPL are one of key driver mutations promoting BCR/ABL-negative myeloproliferative neoplasms (MPNs), but their effects on hematopoietic stem cells (HSCs) and MPN-related hematological abnormalities have not been studied in physiological contexts. Here, we established a MplW514L knock-in mouse model which largely mimics human MPLW515L mutation during hematopoiesis. The mutant mice developed an essential thrombocythemia (ET)-like MPN phenotypes, displaying excess megakaryopoiesis and thrombocytosis and progressive myelofibrosis. Mechanistically we observed that MplW514L-conditioned HSC compartment had a unique disease-initiating capacity however it did not exhibit a obvious advantage of competitive repopulation over wild-type control. Notably, single-cell analysis and flow cytometry profiles support that MplW514L expression led to a significant expansion of megakaryocyte-biased stem cell fate within the HSC pool. Finally, JAK2 inhibitor treatment phenotypically alleviated the ET signs but failed to eliminate the disease-initiating HSCs. These findings underscore the etiology of physiological expression of MPLW515L mutation in HSCs, and also provide a valuable in vivo model to evaluate potential therapeutic options for patients with MPLW515L-positive MPN.
Authors
Shujing Zhang, Jingjing Liu, yuan li, Yi Wang, Lingling Wang, Miaomiao Xu, Yanxia Li, Ge Dong, Shanshan Wang, Yanmei Li, Zhigang Cai, Baobing Zhao
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Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)