Abstract
Passive stiffness of the heart is determined largely by extracellular matrix and titin, which functions as a molecular spring within sarcomeres. Titin stiffening is associated with the development of diastolic dysfunction (DD), while augmented titin compliance appears to impair systolic performance in dilated cardiomyopathy. We found that myofibril stiffness was elevated in mice lacking histone deacetylase 6 (HDAC6). Cultured adult murine ventricular myocytes treated with a selective HDAC6 inhibitor also exhibited increased myofibril stiffness. Conversely, HDAC6 overexpression in cardiomyocytes led to decreased myofibril stiffness, as did ex vivo treatment of mouse, rat, and human myofibrils with recombinant HDAC6. Modulation of myofibril stiffness by HDAC6 was dependent on 282 amino acids encompassing a portion of the PEVK element of titin. HDAC6 colocalized with Z-disks, and proteomics analysis suggested that HDAC6 functions as a sarcomeric protein deacetylase. Finally, increased myofibril stiffness in HDAC6-deficient mice was associated with exacerbated DD in response to hypertension or aging. These findings define a role for a deacetylase in the control of myofibril function and myocardial passive stiffness, suggest that reversible acetylation alters titin compliance, and reveal the potential of targeting HDAC6 to manipulate the elastic properties of the heart to treat cardiac diseases.
Authors
Ying-Hsi Lin, Jennifer L. Major, Tim Liebner, Zaynab Hourani, Joshua G. Travers, Sara A. Wennersten, Korey R. Haefner, Maria A. Cavasin, Cortney E. Wilson, Mark Y. Jeong, Yu Han, Michael Gotthardt, Scott K. Ferguson, Amrut V. Ambardekar, Maggie P.Y. Lam, Chunaram Choudhary, Henk L. Granzier, Kathleen C. Woulfe, Timothy A. McKinsey
Abstract
Subendothelial macrophage internalization of modified lipids and foam cell formation are hallmarks of atherosclerosis. Deubiquitinating enzymes (DUBs) are involved in various cellular activities; however, their role in foam cell formation is not fully understood. Here, using a loss-of-function lipid accumulation screening, we identified ubiquitin-specific peptidase 9 X-linked (USP9X) as a factor that suppressed lipid uptake in macrophages. We found that USP9X expression in lesional macrophages was reduced during atherosclerosis development in both humans and rodents. Atherosclerotic lesions from macrophage USP9X-deficient mice showed increased macrophage infiltration, lipid deposition, and necrotic core content than control apolipoprotein E-knockout (Apoe-/-) mice. Additionally, loss-of-function USP9X exacerbated lipid uptake, foam cell formation and inflammatory responses in macrophages. Mechanistically, the class A1 scavenger receptor (SR-A1) was identified as a USP9X substrate that removed the K63 polyubiquitin chain at the K27 site. Genetic or pharmacological inhibition of USP9X increased SR-A1 cell surface internalization following binding of oxidized low-density lipoprotein (ox-LDL). The K27R mutation of SR-A1 dramatically attenuated basal and USP9X knockdown-induced ox-LDL uptake. Moreover, blocking binding of USP9X to SR-A1 with a cell-penetrating peptide exacerbated foam cell formation and atherosclerosis. In this study, we identified macrophage USP9X as a beneficial regulator of atherosclerosis and revealed the specific mechanisms for the development of potential therapeutic strategies for atherosclerosis.
Authors
Biqing Wang, Xuening Tang, Liu Yao, Yuxin Wang, Zhipeng Chen, Mengqi Li, Naishi Wu, Dawei Wu, Xiangchen Dai, Hongfeng Jiang, Ding Ai
Abstract
Pregnancy is associated with substantial physiological changes of the heart, and disruptions in these processes can lead to peripartum-cardiomyopathy (PPCM). The molecular processes that cause physiological and pathological changes in the heart during pregnancy are not well characterized. Here, we show that mTORc1 was activated in pregnancy to facilitate cardiac enlargement that was reversed after delivery in mice. mTORc1 activation in pregnancy was negatively regulated by the mRNA-destabilizing-protein ZFP36L2 through its degradation of Mdm2 mRNA and P53 stabilization, leading to increased SESN2 and REDD1 expression. This pathway impeded uncontrolled cardiomyocytes hypertrophy during pregnancy, and mice with cardiac-specific Zfp36l2 deletion developed rapid cardiac dysfunction after delivery, while prenatal treatment of these mice with rapamycin improved post-partum cardiac function. Collectively, these data provide a novel pathway for the regulation of mTORc1 through mRNA stabilization of a P53 ubiquitin ligase. This pathway was critical for normal cardiac growth during pregnancy, and its reduction led to PPCM-like adverse remodeling in mice.
Authors
Hidemichi Kouzu, Yuki Tatekoshi, Hsiang-Chun Chang, Jason S. Shapiro, Warren A. McGee, Adam De Jesus, Issam Ben-Sahra, Zoltan Arany, Jonathan Leor, Chunlei Chen, Perry J. Blackshear, Hossein Ardehali
Abstract
Patients with heart failure (HF) have augmented vascular tone, which increases cardiac workload, impairing ventricular output and promoting further myocardial dysfunction. The molecular mechanisms underlying the maladaptive vascular responses observed in HF are not fully understood. Vascular smooth muscle cells (VSMCs) control vasoconstriction via a Ca2+-dependent process, in which the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) on the sarcoplasmic reticulum (SR) plays a major role. To dissect the mechanistic contribution of intracellular Ca2+ release to the increased vascular tone observed in HF, we analyzed the remodeling of IP3R1 in aortic tissues from patients with HF and from controls. VSMC IP3R1 channels from patients with HF and HF mice were hyperphosphorylated by both serine and tyrosine kinases. VSMCs isolated from IP3R1VSMC–/– mice exhibited blunted Ca2+ responses to angiotensin II (ATII) and norepinephrine compared with control VSMCs. IP3R1VSMC–/– mice displayed significantly reduced responses to ATII, both in vivo and ex vivo. HF IP3R1VSMC–/– mice developed significantly less afterload compared with HF IP3R1fl/fl mice and exhibited significantly attenuated progression toward decompensated HF and reduced interstitial fibrosis. Ca2+-dependent phosphorylation of the MLC by MLCK activated VSMC contraction. MLC phosphorylation was markedly increased in VSMCs from patients with HF and HF mice but reduced in VSMCs from HF IP3R1VSMC–/– mice and HF WT mice treated with ML-7. Taken together, our data indicate that VSMC IP3R1 is a major effector of increased vascular tone, which contributes to increased cardiac afterload and decompensation in HF.
Authors
Haikel Dridi, Gaetano Santulli, Jessica Gambardella, Stanislovas S. Jankauskas, Qi Yuan, Jingyi Yang, Steven Reiken, Xujun Wang, Anetta Wronska, Xiaoping Liu, Alain Lacampagne, Andrew R. Marks
Abstract
The causative role of inflammation in hypertension-related cardiovascular diseases is evident and calls for development of specific immunomodulatory therapies. We tested the therapeutic efficacy and mechanisms of action of developmental endothelial locus-1 (DEL-1), an endogenous anti-inflammatory factor, in angiotensin-II (ANGII)- and DOCA (deoxycorticosterone acetate)-salt-induced cardiovascular organ damage and hypertension. By using mice with endothelial overexpression of DEL-1 (EC-Del1) and performing preventive and interventional studies by injecting recombinant DEL-1 in mice, we showed that DEL-1 improved endothelial function and abrogated aortic adventitial fibrosis, medial thickening and loss of elastin. DEL-1 also protected the mice from cardiac concentric hypertrophy, interstitial and perivascular coronary fibrosis and improved left-ventricular function and myocardial coronary perfusion. DEL-1 prevented aortic stiffness and abolished the progression of hypertension. Mechanistically, DEL-1 acted by inhibiting αvβ3-integrin dependent activation of pro-MMP2 in mice and in human isolated aorta. Moreover, DEL-1 stabilized αvβ3-integrin dependent CD25+FoxP3+ Treg numbers and IL-10 levels, which were associated with decreased pro-inflammatory cell recruitment of inflammatory cells and reduced production of pro-inflammatory cytokines in cardiovascular organs. The demonstrated effects and immune-modulating mechanisms of DEL-1 in abrogation of cardiovascular remodeling and progression of hypertension identify DEL-1 as a potential therapeutic factor.
Authors
Theresa Failer, Michael Amponsah-Offeh, Aleš Neuwirth, Ioannis Kourtzelis, Pallavi Subramanian, Peter Mirtschink, Mirko Peitzsch, Klaus Matschke, Sems M. Tugtekin, Tetsuhiro Kajikawa, Xiaofei Li, Anne Steglich, Florian Gembardt, Annika C. Wegner, Christian Hugo, George Hajishengallis, Triantafyllos Chavakis, Andreas Deussen, Vladimir Todorov, Irakli Kopaliani
Abstract
The heart utilizes multiple adaptive mechanisms to maintain pump function. Compensatory cardiac hypertrophy reduces wall stress and oxygen consumption, thereby protecting the heart against acute blood pressure elevation. The nuclear effector of the Hippo pathway, Yes-associated protein 1 (YAP), is activated and mediates compensatory cardiac hypertrophy in response to acute pressure overload (PO). In this study, YAP promoted glycolysis by upregulating glucose transporter 1 (GLUT1), which in turn caused accumulation of intermediates and metabolites of the glycolytic, auxiliary, and anaplerotic pathways during acute PO. Cardiac hypertrophy was inhibited and heart failure was exacerbated in mice with YAP haploinsufficiency in the presence of acute PO. However, normalization of GLUT1 rescued the detrimental phenotype. PO induced accumulation of glycolytic metabolites, including L-serine, L-aspartate, and malate, in a YAP-dependent manner, thereby promoting cardiac hypertrophy. YAP upregulated the GLUT1 gene through interaction with TEAD1 and HIF-1α in cardiomyocytes. Thus, YAP induces compensatory cardiac hypertrophy through activation of the Warburg effect.
Authors
Toshihide Kashihara, Risa Mukai, Shin-ichi Oka, Peiyong Zhai, Yasuki Nakada, Zhi Yang, Wataru Mizushima, Tsutomu Nakahara, Junco S. Warren, Maha Abdellatif, Junichi Sadoshima
Abstract
Mutations in TAB2 (transforming growth factor β activated kinase 1 binding protein 2) have been implicated in the pathogenesis of dilated cardiomyopathy and/or congenital heart disease in humans, but the underlying mechanisms are currently unknown. Here we identified an indispensable role for TAB2 in regulating myocardial homeostasis and remodeling by suppressing RIPK1 (receptor-interacting protein kinase 1) activation and RIPK1-dependent apoptosis and necroptosis. Cardiomyocyte-specific deletion of Tab2 in mice triggered dilated cardiomyopathy with massive apoptotic and necroptotic cell death. Moreover, Tab2-deficient mice were also predisposed to myocardial injury and adverse remodeling following pathological stress. In cardiomyocytes, deletion of TAB2, but not its close homologue TAB3, promoted TNFα-induced apoptosis and necroptosis, which was rescued by forced activation of TAK1 or inhibition of RIPK1 kinase activity. Mechanistically, TAB2 critically mediates RIPK1 phosphorylation at Ser321 via a TAK1-dependent mechanism, which prevents RIPK1 kinase activation and the formation of RIPK1-FADD-caspase-8 apoptotic complex or RIPK1-RIPK3 necroptotic complex. Strikingly, genetic inactivation of RIPK1 with Ripk1-K45A knock-in effectively rescued cardiac remodeling and dysfunction in Tab2-deficient mice. Together, these data demonstrate that TAB2 is a key regulator of myocardial homeostasis and remodeling by suppressing RIPK1-dependent apoptosis and necroptosis. Our results also suggest that targeting RIPK1-mediated cell death signaling may represent a promising therapeutic strategy for TAB2 deficiency-induced dilated cardiomyopathy.
Authors
Haifeng Yin, Xiaoyun Guo, Yi Chen, Yachang Zeng, Xiaoliang Mo, Siqi Hong, Hui He, Jing Li, Rachel Steinmetz, Qinghang Liu
Abstract
Circular RNAs (circRNAs) have been recently recognized as playing a role in the pathogenesis of vascular remodeling–related diseases by modulating the functions of miRNAs. However, the interplay between circRNAs and proteins during vascular remodeling remains poorly understood. Here, we investigated a previously identified circRNA, circEsyt2, whose expression is known to be upregulated during vascular remodeling. Loss- and gain-of‑function mutation analyses in vascular smooth muscle cells (VSMCs) revealed that circEsyt2 enhanced cell proliferation and migration and inhibited apoptosis and differentiation. Furthermore, the silencing of circEsyt2 in vivo reduced neointima formation, while circEsyt2 overexpression enhanced neointimal hyperplasia in the injured carotid artery, confirming its role in vascular remodeling. Using unbiased protein–RNA screening and molecular validation, circEsyt2 was found to directly interact with polyC-binding protein 1 (PCBP1), an RNA splicing factor, and regulate PCBP1 intracellular localization. Additionally, circEsyt2 silencing substantially enhanced p53β splicing via the PCBP1–U2AF65 interaction, leading to the altered expression of p53 target genes (cyclin D1, p21, PUMA, and NOXA) and the decreased proliferation of VSMCs. Thus, we identified a potentially novel circRNA that regulated vascular remodeling, via altered RNA splicing, in atherosclerotic mouse models.
Authors
Xue Gong, Miao Tian, Nian Cao, Peili Yang, Zaicheng Xu, Shuo Zheng, Qiao Liao, Caiyu Chen, Cindy Zeng, Pedro A. Jose, Da-Zhi Wang, Zhao Jian, Yingbin Xiao, Ding-Sheng Jiang, Xiang Wei, Bing Zhang, Yibin Wang, Ken Chen, Gengze Wu, Chunyu Zeng
Abstract
Repair of the infarcted heart requires TGF-β/Smad3 signaling in cardiac myofibroblasts. However, TGF-β-driven myofibroblast activation needs to be tightly regulated in order to prevent excessive fibrosis and adverse remodeling that may precipitate heart failure. We hypothesized that induction of the inhibitory Smad, Smad7 may restrain infarct myofibroblast activation, and we examined the molecular mechanisms of Smad7 actions. In a mouse model of non-reperfused infarction, Smad3 activation triggered Smad7 synthesis in α-SMA+ infarct myofibroblasts, but not in α-SMA-/PDGFRα+ fibroblasts. Myofibroblast-specific Smad7 loss increased heart failure-related mortality, worsened dysfunction, and accentuated fibrosis in the infarct border zone and in the papillary muscles. Smad7 attenuated myofibroblast activation and reduced synthesis of structural and matricellular extracellular matrix proteins. Smad7 actions on TGF-β cascades involved de-activation of Smad2/3 and non-Smad pathways, without any effects on TGF-β receptor activity. Unbiased transcriptomic and proteomic analysis identified receptor tyrosine kinase signaling as a major target of Smad7. Smad7 interacted with Erbb2 in a TGF-independent manner and restrained Erbb1/Erbb2 activation, suppressing fibroblast expression of fibrogenic proteases, integrins and CD44. Smad7 induction in myofibroblasts serves as an endogenous TGF-β-induced negative feedback mechanism that inhibits post-infarction fibrosis by restraining Smad-dependent and Smad-independent TGF-β responses, and by suppressing TGF-independent fibrogenic actions of Erbb2.
Authors
Claudio Humeres, Arti V. Shinde, Anis Hanna, Linda Alex, Silvia C. Hernandez, Ruoshui Li, Bijun Chen, Simon J. Conway, Nikolaos G. Frangogiannis
Abstract
Various population of cells are recruited to the heart after cardiac injury but little is known about whether the cardiomyocyte directly regulates heart repair. In a murine model of ischemic cardiac injury, we demonstrate that the cardiomyocyte plays a pivotal role in heart repair by regulating nucleotide metabolism and fates of non-myocytes. Cardiac injury induced the expression of the ectonucleotidase ENPP1 that hydrolyzes extracellular ATP to form AMP. In response to AMP, the cardiomyocyte released adenine and specific ribonucleosides that disrupted pyrimidine biosynthesis at OMP synthesis step, induced genotoxic stress and a p53 mediated cell death of cycling non-myocytes. As non-myocytes are critical for heart repair, we showed that rescue of pyrimidine biosynthesis by administration of uridine or by genetic targeting of ENPP1/AMP pathway enhanced repair after cardiac injury. We identified ENPP1 inhibitors on small molecule screening and showed that systemic administration of an ENPP1 inhibitor after heart injury rescued pyrimidine biosynthesis in non-myocyte cells, augmented cardiac repair and post infarct heart function. These observations demonstrate that the cardiac muscle cell by releasing adenine and specific nucleosides after heart injury regulates pyrimidine metabolism in non-muscle cells and provide insight into how inter-cellular regulation of pyrimidine biosynthesis can be targeted and monitored for augmenting tissue repair.
Authors
Shen Li, Tomohiro Yokota, Ping Wang, Johanna ten Hoeve, Feiyang Ma, Thuc M. Le, Evan R. Abt, Yonggang Zhou, Rimao Wu, Maxine Nanthavongdouangsy, Abraham Rodriguez, Yijie Wang, Yen-Ju Lin, Hayato Muranaka, Mark Sharpley, Demetrios T. Braddock, Vicky E. MacRae, Utpal Banerjee, Pei-Yu Chiou, Marcus Seldin, Dian Huang, Michael Teitell, Ilya Gertsman, Michael Jung, Steven J. Bensinger, Robert Damoiseaux, Kym Faull, Matteo Pellegrini, Aldons Lusis, Thomas G. Graeber, Caius G. Radu, Arjun Deb
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)