Abstract
Abdominal aortic aneurysm (AAA) lacks effective pharmacological therapies. Here, we investigate transcription factor 7-like 2 (TCF7L2), a genetic locus associated with both thoracic and abdominal aortic aneurysms, to elucidate its role in AAA pathogenesis. Integrating summary-data-based Mendelian randomization (SMR) with single-cell RNA sequencing (scRNA-seq) of human and mouse aortas, we identify TCF7L2 as a gene enriched in vascular smooth muscle cells (VSMCs) and causally linked to AAA development. Smooth muscle cell-specific TCF7L2 knockout significantly attenuates AAA formation across three distinct murine models (Ang II infusion-, BAPN/Ang II co-administration-, and elastase-induced AAA), independent of systemic blood pressure or lipid levels. Mechanistic studies reveal that TCF7L2 directly upregulates MMP14 and downregulates TIMP3 expression in vitro and in vivo, driving MMP2-mediated extracellular matrix (ECM) degradation. Concurrently, TCF7L2 represses integrin β1 (ITGB1) expression, reducing VSMC adhesion to the ECM. Collectively, these findings identify TCF7L2 as a key driver of pathological vascular remodeling in AAA, suggesting that targeting TCF7L2 may offer a novel therapeutic strategy for limiting AAA progression.
Authors
Yongjie Deng, Yaozhong Liu, Yang Zhao, Hongyu Liu, Guizhen Zhao, Zhenguo Wang, Xu Zhang, Chao Xue, Wei Huang, Tianqing Zhu, Haocheng Lu, Yanhong Guo, Lin Chang, Ida Surakka, Y. Eugene Chen, Jifeng Zhang
Abstract
Heterozygous TBX4 variants are the second most common genetic cause of pediatric pulmonary hypertension (PH), yet mechanisms underlying TBX4-related lung disease remain poorly understood. This study developed a lung mesenchyme-specific Tbx4 loss-of-function (Tbx4cKO) mouse model that bypasses embryonic lethality to investigate this condition. Adult Tbx4cKO mice demonstrated significantly impaired pulmonary flow acceleration consistent with PH. Three-dimensional analysis of embryonic lungs revealed reduced lobe volumes and decreased distance between pleural edges and muscularized vessels. In adult Tbx4cKO lungs, we identified extensive vascular remodeling characterized by medial thickening and the extension of muscularized arteries into normally non-muscularized subpleural parenchymal zones. Contrary to previous reports suggesting vascular simplification, three-dimensional analysis demonstrated an elaborated pulmonary artery (PA) tree in addition to pathologic wall muscularization. Depletion of a single Tbx5 allele in addition to both Tbx4 alleles exacerbated histologic phenotypes with worsened right ventricular dilation. This model also demonstrated dysregulated airway smooth muscle patterning and prominent subpleural smooth muscle bands, similar to those in human TBX4 syndrome. We identify TBX4 as a critical regulator of smooth muscle differentiation and patterning across multiple lung compartments. Our model recapitulates key features of human TBX4 syndrome and identifies dysregulated smooth muscle differentiation as a potential future therapeutic target.
Authors
Lea C. Steffes, Kaylie A. Chiles, Sehar R. Masud, Aleen Rahman, Madeline Dawson, Csaba Galambos, Maya E. Kumar, Ripla Arora
Abstract
Aortic dissection (AD) is a catastrophic vascular emergency with high mortality, and current pharmacologic interventions to prevent its progression are limited. Vascular smooth muscle cells (VSMCs) undergo a pathological phenotypic switch from a contractile to a synthetic state during AD, compromising aortic wall integrity; however, the underlying metabolic mechanisms remain poorly understood. In this study, we performed integrative transcriptomic analyses and identified glutaminase 1 (GLS1) as a key regulator of VSMC phenotypic switching in AD. GLS1 expression was significantly downregulated in VSMCs from both human AD aortic tissues and mouse models. Functionally, GLS1 deficiency promoted PDGF-BB–induced VSMC dedifferentiation in vitro. Smooth muscle cells specific Gls1 knockout (Gls1SMKO) mice exhibited aggravated AD upon BAPN treatment, whereas VSMCs specific GLS1 overexpression improved the contractile phenotype and reduced AD incidence. Mechanistically, GLS1 downregulation impaired glutamate metabolism, leading to reduced levels of glutathione and α-ketoglutarate. This metabolic disruption promoted reactive oxygen species accumulation and mitochondrial dysfunction, ultimately triggering VSMC phenotypic switching. Furthermore, we found that GLS1 transcription was repressed by retinoic acid receptor-α (RARα). Pharmacologic inhibition of RARα with AR7 restored GLS1 expression, ameliorated VSMC phenotypic switching, and conferred protection against AD. These findings reveal a critical role of GLS1-mediated glutamate metabolism in VSMC phenotypic switching and suggest a promising therapeutic strategy for AD.
Authors
Wei Xie, Chen Ning, Chen Lu, Dongjin Wang, Shuang Zhao, Tianyu Song, Hailong Cao
Abstract
Increased consumption of ultra-processed foods (UPFs) is a risk factor for metabolic disorders-associated heart failure (HF). Here, we demonstrate that UPF-induced calpain-1 aggravated oxidative stress, thereby increasing high mobility group box 1 (HMGB1)-mediated myocardial inflammation, which contributes to cardiac dysfunction. After illustrating the dysregulated inflammatory pathways in human and murine hearts upon metabolic stress, we revealed an increase in calpain-1 alongside profound oxidative stress and inflammation in the failing myocardium. Mechanistically, in neonatal rat cardiomyocytes (NRCMs) and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), HMGB1 was upregulated by calpain-1 and reactive oxygen species (ROS) upon stress of saturated and trans fatty acids (FA). Consequently, HMGB1 promoted a pro-inflammatory response in macrophages. On the contrary, inhibition of calpain or ROS efficiently repressed HMGB1 in cardiomyocytes. Therapeutically, either recombinant adeno-associated virus 9 (AAV9) delivered inhibitor of calpain-1 or its pharmacological inhibitor attenuated ROS and HMGB1-induced inflammation in the myocardium and mitigated HF in both male and female mice fed with an ultra-processed diet (UPD). Collectively, we have demonstrated the effects of suppressing calpain-1 and oxidative stress on alleviating myocardial inflammation via blockage of HMGB1 and cardiac dysfunction. The results provide a promising therapeutic strategy for preventing or treating HF in metabolic disorders.
Authors
Claire Ross, Sanskruti Ravindra Gare, Nasser H. Alatawi, Oveena Fonseka, Xinyi Chen, Jiayan Zhang, Yihua Han, Andrea Ruiz-Velasco, Riham R.E. Abouleisa, Yingjuan Liu, Xiangjun Zhao, Han Xiao, Bernard Keavney, Gareth J. Howell, Tao Wang, Tamer M.A. Mohamed, Elizabeth J. Cartwright, Wei Liu
Abstract
Heart failure with preserved ejection fraction (HFpEF) is a multifactorial disease that develops in several clinical settings. Despite its complex pathogenesis, evidence indicates a central role for fibrosis in the progression of left ventricular (LV) diastolic dysfunction (LVDD). Through exploratory research into brown adipose tissue (BAT)-derived adipokines (BATokines), we identified a secreted-type pro-fibrotic protein, procollagen C-endopeptidase enhancer-1 (PCPE-1), whose expression increased in BAT with aging. PCPE-1 promotes the cleavage of procollagens and is a critical initiator of fibrillogenesis. This molecule was increased in the plasma of aged mice. In addition to aging, dietary obesity led to an increase in PCPE-1 expression in the LV of mice. Both systemic and BAT-specific PCPE-1 depletion ameliorated LV fibrosis and LVDD in the obese HFpEF model. Our data also showed that age-associated LVDD was ameliorated in the systemic PCPE-1 knockout mouse model fed with a normal chow diet. Conversely, the overexpression of PCPE-1 expression in BAT was shown to lead to aggravation of LV fibrosis and LVDD. Mechanistically, we found reactive oxygen species (ROS)/DNA damage/c-Fos/c-Jun signaling resulted in an increased production of PCPE-1 in brown adipocytes. These results indicate PCPE-1 may represent a druggable target for aging- and obesity-related HFpEF.
Authors
Yung-Ting Hsiao, Yohko Yoshida, Hirotsugu Tsuchimochi, Jingyuan Tang, Tin May Aung, Chun-Han Chang, Agian Jeffilano Barinda, Zhihong Li, Nur Syakirah Binti Othman, Tom Yoshizaki, Yiwei Ling, Shujiro Okuda, Manabu Abe, Seiya Mizuno, Satoru Takahashi, Takayuki Inomata, Hidetaka Kioka, Yasushi Sakata, Daichi Maeda, Yuya Matsue, Takaaki Furihata, Hiroshi Iwata, James T. Pearson, Kinya Otsu, Kenneth Walsh, Akihito Ishigami, Tohru Minamino, Ippei Shimizu
Abstract
Short QT syndrome is a heritable arrhythmia disorder linked to sudden cardiac death. We recently identified that individuals with alternating hemiplegia of childhood (AHC), a rare neurodevelopmental disorder, can exhibit shortened corrected QT intervals and elevated risk for ventricular fibrillation. This is especially true for patients with AHC heterozygous for the recurrent ATP1A3-D801N variant, though the underlying cardiac mechanism remains unclear. We hypothesized that the D801N missense impairs Na+/K+-ATPase function, causing Ca2+ overload, shortened action potential duration (APD), and arrhythmias. Using in silico modeling and patient-derived induced pluripotent stem cell cardiomyocytes (iPSC-CMsD801N), we observed shorter APD, elevated intracellular and sarcoplasmic reticulum Ca2+ levels, and delayed afterdepolarizations (DADs) compared with WT. Additionally, increased Ca²+ influx via the Na+/Ca2+ exchanger (NCX1) during depolarization was observed in iPSC-CMsD801N. Simulations and in vitro experiments suggest that reduced ATPase function accelerated inactivation of L-type Ca2+ channels. Pharmacologic inhibition of NCX1 with ORM-10103 normalized APD and reduced DADs. These findings support a Ca2+-mediated mechanism for arrhythmogenesis in ATP1A3-D801N carriers and identify NCX1 as a potential therapeutic target.
Authors
Minu-Tshyeto K. Bidzimou, Padmapriya Muralidharan, Zhushan Zhang, Danyal Raza, Daniel Needs, Bo Sun, Robin M. Perelli, Mary E. Moya-Mendez, P.K. Rakesh Manivannan, Arsen S. Hunanyan, Abbigail Helfer, Christine Q. Simmons, Alfred L. George Jr., Donald M. Bers, Nenad Bursac, Mohamad A. Mikati, Andrew P. Landstrom
Abstract
The RhoBTB1-Cullin3 (CUL3) pathway in smooth muscle cells (SMCs) controls the ubiquitination and proteasomal degradation of target proteins that regulate vasodilation, vasoconstriction, and the actin cytoskeleton, and through this blood pressure (BP) and arterial stiffness. Using proximity labelling coupled with mass spectrometry in A7R5 SMCs, we identified proteins which bound to the C-terminal half of RhoBTB1 which functions as an adapter to deliver substrates to CUL3. We examined the physiological relevance of one of these substrates, RbFox2. Co-immunoprecipitation validated the interaction of RbFox2 with RhoBTB1. RbFox2 expression was elevated in response to inhibition of the ubiquitination-proteasomal pathway, CUL3-deficiency, and RhoBTB1 inhibition by either siRNA or angiotensin II (ANG). RbFox2 was ubiquitinated in a RhoBTB1- and CUL3-dependent manner suggesting its regulation through the RhoBTB1-CUL3-dependent ubiquitin-proteasome pathway. Inhibition of RbFox2 impaired the actin cytoskeleton in A7R5 cells and in primary SMC from RbFox2Flox/Flox (RbFox2F/F) mice and decreased the levels of globular and filamentous actin. ANG increased BP and arterial stiffness of RbFox2F/F mice, but the progression of arterial stiffness was halted after SMC-specific RbFox2 deletion despite a continued rise in BP. We conclude that RhoBTB1 and RbFox2 are important regulators of arterial stiffness through a mechanism that influences cytoskeletal integrity.
Authors
Gaurav Kumar, Nisita Chaihongsa, Daniel T. Brozoski, Daria Golosova, Ibrahim Vazirabad, Ko-Ting Lu, Kelsey K. Wackman, Ravi K. Singh, Curt D. Sigmund
Abstract
Authors
Robert Lakin, Xueyan Liu, Dana Sherrard, Mihir Parikh, Ryan Debi, Nazari Polidovitch, Markus J. Duncan, Jian Wu, Peter H. Backx
Abstract
Myotonic Dystrophy Type 1 (DM1) is caused by an expanded CTG repeat in the DMPK gene, resulting in mutant transcripts that form expanded CUG (CUGexp) RNA foci and sequester muscleblind-like (MBNL) RNA-binding proteins. DM1 is multisystemic with progressive worsening of disease manifestations in affected tissues. Disease progression is attributed to somatic expansion of the CTG repeats with age, resulting in production of CUGexp RNA with enhanced intrinsic toxicity due to increased MBNL sequestration. To determine the degree to which cardiac disease progression can occur independently of repeat expansion, we used a transgenic DM1 mouse model with inducible heart-specific expression of a stable, interrupted 960-CUG repeat RNA. Sustained CUGexp RNA expression caused progressive cardiac enlargement, contractile dysfunction, conduction delay, myocardial fibrosis, and reduced survival, while MBNL-dependent splicing defects remained static, consistent with the stable repeat length. We also determined the degree of reversibility after different periods of CUGexp RNA expression by shutting off the repeat-containing transgene. Suppression of CUGexp RNA expression rescued cardiac abnormalities, but reversibility declined with longer exposure to the toxic RNA. These findings demonstrate that prolonged expression of stable CUGexp RNA drives progressive cardiac pathology, revealing a mechanism of disease progression in DM1 in addition to somatic expansion.
Authors
Rong-Chi Hu, Mohammadreza Tabary, Xander H.T. Wehrens, Thomas A. Cooper
Abstract
Resident cardiac fibroblast (RCF)-derived cardiac myofibroblasts (CMF) contribute to myocardial repair but also drive adverse ventricular remodeling and contractile dysfunction after myocardial infarction (MI). The sodium-activated potassium channel Slick (Slo2.1) has been described in cardiomyocyte (CM) mitochondria; however, transcriptomic analyses indicate higher Slick expression in RCFs/CMFs. Here, we investigated the role of Slick in cardiac fibroblast function and post-MI remodeling. Using live-cell imaging and whole-cell patch-clamp recordings, we found that plasma membrane Slick channels in RCFs and CMFs regulated potassium (K+) efflux and modulated store-operated calcium entry (SOCE), particularly in CMFs. Global Slick KO and conditional CMF-specific KO hearts exhibited reduced fibrosis and preserved left ventricular function following ischemia/reperfusion injury. This cardioprotection was associated with diminished CMF activation and proliferation, reduced inflammation, and improved CM survival post-MI. Collectively, these findings identify fibroblast Slick channels as regulators of SOCE-dependent fibrogenesis and demonstrate that their deletion mitigates maladaptive remodeling and functional decline after MI.
Authors
Jiaqi Yang, Lin Zhu, David Spähn, Melanie Cruz Santos, Sophia Schanz, Selina Maier, Lena Birkenfeld, Helmut Bischof, Anna Roslan, Nina Wettschureck, Oliver Borst, Lucas Matt, Robert Lukowski
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