Abstract
Atrial fibrillation (AF) is the most common sustained human cardiac arrhythmia and linked to a drastic increase in stroke and heart failure risk. While sequence variations in the PITX2 non-coding region are the strongest genetic signature of AF risk, the direct role of PITX2 in AF remains a topic of debate. Here, we generated a mouse model (Pitx2Pro41Ser) of a human PITX2 coding variant linked to increased AF risk in the Finnish population. The Pitx2Pro41Ser mice exhibit near-complete penetrance of pacing-induced AF, and transcriptional profiling indicates that Pitx2Pro41Ser is a loss-of-function mutation. In vivo cleavage under targets and tagmentation (CUT&Tag) reveals that PITX2 acts as a transcriptional repressor in developing left atrial cardiomyocytes independent of DNA methylation. Ectopic Pitx2 expression in postnatal right atrial cardiomyocytes via adeno-associated virus (AAV) delivery or genetic overexpression represses right atrial genes and induces a left atrial transcriptome, revealing unexpected plasticity of postnatal atrial cardiomyocytes. Strikingly, delivery of Pitx2 AAV into Pitx2Pro41Ser mice rescues AF inducibility uncovering a direct link between PITX2 activity and AF susceptibility.
Authors
Jeffrey D. Steimle, Yue Yuan, Shaohai Fang, Vaibhav Deshmukh, Christine Rodriguez, Fansen Meng, Taotao Tan, Md. Abul Hassan Samee, Yun Huang, Na Li, James F. Martin
Abstract
Chronic kidney disease (CKD) disrupts mineral homeostasis, leading to impaired skeletal mineralization and cardiovascular pathology, yet the mechanism linking these processes remains undefined. Here we identify glycerol-3-phosphate acyltransferase 2 (GPAT2) as a regulator that couples free fatty acid (FFA) partitioning in osteoblasts to systemic phosphate balance. In mouse and human CKD, elevated osteoblast GPAT2 routes FFA away from mitochondrial oxidation, limiting phosphate incorporation into bone, and toward lysophosphatidic acid synthesis, increasing production of the phosphaturic hormone fibroblast growth factor 23 (FGF23). By contrast, osteoblast-specific Gpat2 deletion restores osteoblast FFA oxidation and skeletal phosphate incorporation, lowers circulating phosphate and FGF23, and attenuates vascular calcification and cardiac hypertrophy in CKD. Further, a bone-targeted GPAT inhibitor recapitulates most of these beneficial effects. These findings establish a fundamental role for osteoblast lipid metabolism in mineral homeostasis and identify GPAT2 in bone as a promising therapeutic target for both skeletal and cardiovascular complications of CKD.
Authors
Petra Simic, Han Xie, Wen Zhou, Yu Fan, Renata C. Pereira, Fangcong Dong, Jason D. Roh, Isidro B. Salusky, Charandeep Singh, Russell P. Goodman, Ashok Khatri, Eugene P. Rhee
Abstract
Authors
Rong Tian, E. Douglas Lewandowski
Abstract
Authors
Chai-Wan Kim, Matthew A. Mitsche, Jay D. Horton
Abstract
Authors
Diwakar Turaga, Chang-Ru Tsai, Yuka Morikawa, Hanna J. Tadros, Yi Zhao, Lalita Wadhwa, Iki Adachi, Xiao Li, James F. Martin
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
Authors
Seyi E. Elasoru, Christian Miccile, Jingwu Pan, Zhaoyang Zhang, Kalyanam Shivkumar, Herbert Herzog, Robert D. Harvey, Zhilin Qu, Olujimi A. Ajijola
Abstract
The endocardium is a major source of coronary angiogenesis and arterialization, through coordinated cell fate transition and migration. However, the transcriptional regulatory network synchronizing cell fate determination and movement remains unclear. Here, we identified transcription factor HAND2 as a key candidate for coronary vascular formation. Endocardial deletion of Hand2 in mice disrupted arterial-venous networks and stunted coronary arteries, paralleling a ventricular noncompaction phenotype. Moreover, deletion of Hand2 produced excessive tip cells with defective movement. RNA-seq analysis revealed enhanced hypoxic metabolic activation but declined TGF-β/p38MAPK-dependent endothelial-to-mesenchymal transition (Endo-MT). In consistence, genetic inhibition of the core hypoxic regulators or pharmaceutical administration of TGFβ2 partially recovered the coronary arterial defects in Hand2 mutants. Furthermore, HAND2 was found directly bound to promoters of the target genes, harmonizing cell migration and cell fate transition. These findings pinpoint HAND2 as an essential regulator of the endocardial transcriptional regulatory network for coronary arterialization and provide potential therapeutic targets for coronary artery diseases.
Authors
Huijuan Wang, Haosheng Zhang, Leiyin Zheng, Peihan Zhang, Yuqian Wang, Sijia Ding, Wenping Liu, Yuanming Cheng, Zhongzhou Yang, Wen Luo
Abstract
Myofibroblasts are the cells responsible for collagen production, leading to tissue fibrosis. Because 20.5% of the total amino acids in collagen are proline, myofibroblasts must acquire a well-developed proline-producing mechanism during their differentiation. However, the detailed mechanism for myofibroblasts to acquire and keep the developed proline biosynthesis machinery remains obscure. Here, we show branched-chain amino acid transaminase 1 (Bcat1) is up-regulated in a substantial subset of Postn-expressing proto-myofibroblast-like fibroblasts, transitional cells en route to fully differentiated myofibroblasts, as well as in myofibroblasts in the fibrotic heart and liver of mice and humans and promotes the proline production. The branched-chain amino acid (BCAA) production by BCAT1 promotes SMAD3 phosphorylation via HDAC5 phosphorylation at Ser488, thereby enhancing SMAD3-dependent transcription of proline biosynthesis-related genes, Aldh18a1, Pycr1, and Eprs, in proto-myofibroblast-like fibroblasts and myofibroblasts. In BCAT1-deficient mice, expression of proline biosynthesis-related genes is significantly attenuated in their hearts after myocardial infarction, resulting in decreased cardiac fibrosis. Moreover, BCAT1 inhibitor treatment of mice with myocardial infarction reduces cardiac fibrosis. Our results identified a BCAT1-mediated pathway that promotes collagen production via proline biosynthesis regulation in proto-myofibroblast-like fibroblasts and myofibroblasts, which may provide a therapeutic target for cardiac fibrosis.
Authors
Noburo Takizawa, Takanori Hironaka, Hayato Watanabe, Haruna Suetsugu, Keisuke Yoshioka, Yuma Horii, Yuri Nagata, Hiroaki Matoba, Hidetaka Kosako, Kenji Hamase, Go Hirai, Michio Nakaya
Abstract
Gut microbiota-derived trimethylamine N-oxide (TMAO) plays a role in the pathogenesis of cardiovascular disease. The role of TMAO in the pathogenesis of atrial fibrillation (AF) remains uncertain. TMAO levels were quantified in plasma from serial subjects undergoing elective cardiac catheterizations (N=5090) and shown to independently associate with prevalent AF following adjustment for risk factors (TMAO adjusted odds ratio 1.7 [95% confidence interval 1.3-2.1]; P<0.01). Human cAMP response element modulator isoform IbΔC-X transgenic mice (CREM-IbΔC-X), a spontaneous mouse model of AF, supplemented with a TMAO diet developed AF sooner. C57BL/6J mice on and off a TMAO had more inducible AF via a transesophageal pacing study compared to chow controls. Dietary choline supplementation increased circulating TMAO levels and significantly accelerated AF onset in CREM-IbΔC-X mice (P<0.01). Iodomethylcholine (IMC), the gut microbial CutC/D inhibitor that suppresses choline→TMA(O) metabolic transformation, reduced circulating TMAO levels (P<0.0001) and choline induced AF onset (P<0.01). Cecal metagenomic analyses showed that choline supplementation induced changes in microbial communities associated with AF, while many of these changes were attenuated by IMC. Choline supplementation promoted overall adverse atrial remodeling with left atrial dilation. Optical mapping studies showed that mice supplemented with choline exhibited reduced conduction velocity, shortened action potential duration at 80% repolarization, and decreased wavelength. TMAO inhibits muscarinic receptor 2 resulting in autonomic dysfunction that promotes AF. In summary, the gut microbial metabolite TMAO, independently associated with AF risk in subjects, enhances AF in multiple AF mouse models via autonomic dysfunction, and is a therapeutic target for prevention of AF.
Authors
Selvam Arjunan, Isaiah Pemberton, Xinmin S. Li, Naseer Sangwan, Lydia Akino, Emmanuel Opoku, Dmitriy Verbovetskiy, Ina Nemet, Hyun Su Kim, Haruko Masumiya, Zeneng Wang, Joseph A. Lupica, Melissa Y. Tian, Karis Mao, Deepthi P. Mallela, Maradumane Mohan, Sarah Schumacher, Julie H. Rennison, Sathyamangla Prasad, Kenneth R. Laurita, Vamsi Chodisetty, Mina K. Chung, David R. Van Wagoner, John Barnard, Jonathan D. Smith, Oussama Wazni, Stanley L. Hazen, Robert A. Koeth
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)