Introduction: Defects in ATP production lead to cardiac dysfunction and heart failure (HF) while restoring reduced mitochondrial (Mito) function mitigates HF. Previously we showed that a novel Mito protein, Perm1 (PGC-1 and ERR-induced regulator, muscle 1), promotes Mito biogenesis in cardiomyocytes (CM). Here we studied the role of myocardial Perm1 in vivo . Hypothesis: Perm1 protects the heart from pressure overload-induced dysfunction. Methods: First, we generated cardiac-specific Perm1 transgenic mice (Perm1cTG). Next, we induced pressure overload by transverse aortic constriction (TAC) or performed Sham operations on 10-week-old control (CTL) and Perm1cTG male mice. Heart function, histology, and biochemical analyses were performed eight weeks postoperatively. To understand the mechanism of Perm1, the heart protein samples were subjected to quantitative mass spectrometry (MS) analysis, and we also identified Perm1 binding proteins in the heart by MS. Finally, mouse neonatal CM were infected with adenoviruses expressing shMic60 (knock down) or shControl in combination with Perm1 or LacZ, followed by oxygen consumption rate (OCR) analysis. Results: Sham-operated Perm1cTG and CTL mice showed no differences in function and morphology. Following TAC, CTL developed severely reduced heart function, while Perm1cTG had only minimal change. Perm1cTG TAC mice also showed reduced cardiac hypertrophy, Anf and Bnp mRNA expression, and fibrosis, compared to CTL TAC, showing Perm1 protects the heart from hemodynamic stress. Perm1cTG TAC hearts showed significantly increased OCR compared to CTL TAC, suggesting Perm1 preserves TAC-induced CM Mito dysfunction. MS analysis identified MICOS (mitochondrial contact site and cristae organizing system) and oxidative phosphorylation proteins were upregulated in Perm1cTG TAC hearts compared to CTL TAC. Moreover, we found that Perm1 binds to Mic60, which is a core component of the MICOS. Finally, Mic60 was required for Perm1-induced maximal oxidative capacity, suggesting Perm1 acts through Mic60. Conclusion: Perm1 protects the heart against pressure overload by restoring oxidative metabolism. Future studies will reveal the role of Perm1/Mic60 in the heart. This work is supported by NIH R01HL151239.

Integrins are cell surface receptors expressed ubiquitously including on cardiac cells, which are critical for maintaining homeostasis in the cardiovascular system in health and function as key modulators of cardiac disease. They govern most facets of cardiac myocyte and fibroblast cellular function, act as important bidirectional mechanoreceptors, and interact with and respond to the extracellular matrix and its varied components. In this chapter, we focus on the growing body of knowledge identifying which of the integrin family members are expressed in the heart in health and disease, delineating the expression patterns of integrins in cardiac myocytes and fibroblasts, while highlighting important lessons learnt from cellular and animal models of cardiac disease. We will also highlight aspects of integrin biology obtained from humans, as available. Integrins lack intrinsic enzymatic activity to transduce mechanical to biochemical signaling, therefore, we will also discuss some of the identified binding and adapter proteins involved in integrin-mediated cell signaling relevant to the heart. We will present the currently understood therapeutic potential of select integrins in specific cardiac diseases, such as that following myocardial infarction or development of various cardiomyopathies. Most of this work has been largely unexplored in human cardiac disease. Finally, we highlight some of the pitfalls that have hampered our understanding of integrin and integrin-related protein targeting in heart disease and discuss the reemergence of integrins as attractive therapeutic targets.

HomeCirculationVol. 147, No. 11Perm1 Protects the Heart From Pressure Overload–Induced Dysfunction by Promoting Oxidative Metabolism No AccessLetterRequest AccessFull TextAboutView Full TextView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toNo AccessLetterRequest AccessFull TextPerm1 Protects the Heart From Pressure Overload–Induced Dysfunction by Promoting Oxidative Metabolism Shizuko Tachibana, Nam-Kyung Yu, Ruixia Li, Carolina Fernandez-Costa, Alex Liang, Janet Choi, Dayoen Jung, Changchun Xiao, Anastasia Kralli, John R. Yates III, Robert S. Ross and Yoshitake Cho Shizuko TachibanaShizuko Tachibana Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). , Nam-Kyung YuNam-Kyung Yu Departments of Molecular Medicine and Neurobiology (N.-K.Y., C.F.-C., J.R.Y.), The Scripps Research Institute, La Jolla, CA. , Ruixia LiRuixia Li Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). Department of Medicine/Cardiology, Veterans Administration Healthcare, San Diego, CA (R.L., A.L., R.S.R., Y.C.). , Carolina Fernandez-CostaCarolina Fernandez-Costa Departments of Molecular Medicine and Neurobiology (N.-K.Y., C.F.-C., J.R.Y.), The Scripps Research Institute, La Jolla, CA. , Alex LiangAlex Liang Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). Department of Medicine/Cardiology, Veterans Administration Healthcare, San Diego, CA (R.L., A.L., R.S.R., Y.C.). , Janet ChoiJanet Choi Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). , Dayoen JungDayoen Jung Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). , Changchun XiaoChangchun Xiao Department of Immunology and Microbiology (C.X.), The Scripps Research Institute, La Jolla, CA. , Anastasia KralliAnastasia Kralli Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD (A.K.). , John R. Yates IIIJohn R. Yates III Departments of Molecular Medicine and Neurobiology (N.-K.Y., C.F.-C., J.R.Y.), The Scripps Research Institute, La Jolla, CA. , Robert S. RossRobert S. Ross Correspondence to: Robert S. Ross, MD, MBA, Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093. Email E-mail Address: [email protected] https://orcid.org/0000-0003-2195-8982 Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). Department of Medicine/Cardiology, Veterans Administration Healthcare, San Diego, CA (R.L., A.L., R.S.R., Y.C.). and Yoshitake ChoYoshitake Cho Correspondence to: Yoshitake Cho, PhD, Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093. Email E-mail Address: [email protected] https://orcid.org/0000-0002-7161-3248 Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, La Jolla (S.T., R.L., A.L., J.C., D.J., R.S.R., Y.C.). Department of Medicine/Cardiology, Veterans Administration Healthcare, San Diego, CA (R.L., A.L., R.S.R., Y.C.). Originally published13 Mar 2023https://doi.org/10.1161/CIRCULATIONAHA.122.060173Circulation. 2023;147:916–919FootnotesCirculation is available at www.ahajournals.org/journal/circFor Sources of Funding and Disclosures, see page 919.Correspondence to: Yoshitake Cho, PhD, Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093. Email [email protected]ucsd.eduCorrespondence to: Robert S. Ross, MD, MBA, Division of Cardiovascular Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093. Email [email protected]ucsd.eduReferences1. Brown DA, Perry JB, Allen ME, Sabbah HN, Stauffer BL, Shaikh SR, Cleland JG, Colucci WS, Butler J, Voors AA, et al. Expert consensus document: mitochondrial function as a therapeutic target in heart failure.Nat Rev Cardiol. 2017; 14:238–250. doi: 10.1038/nrcardio.2016.203CrossrefMedlineGoogle Scholar2. Cho Y, Tachibana S, Lam K, Arita Y, Khosrowjerdi S, Zhang O, Liang A, Li R, Andreyev A, Kralli A, et al. Correction: Perm1 promotes cardiomyocyte mitochondrial biogenesis and protects against hypoxia/reoxygenation-induced damage in mice.J Biol Chem. 2021; 297:101121. doi: 10.1016/j.jbc.2021.101121CrossrefMedlineGoogle Scholar3. Rauniyar N, Yates JR. Isobaric labeling-based relative quantification in shotgun proteomics.J Proteome Res. 2014; 13:5293–5309. doi: 10.1021/pr500880bCrossrefMedlineGoogle Scholar4. Rampelt H, Zerbes RM, van der Laan M, Pfanner N. Role of the mitochondrial contact site and cristae organizing system in membrane architecture and dynamics.Biochim Biophys Acta Mol Cell Res. 2017; 1864:737–746. doi: 10.1016/j.bbamcr.2016.05.020CrossrefMedlineGoogle Scholar5. Bock T, Turk C, Aravamudhan S, Keufgens L, Bloch W, Rozsivalova DH, Romanello V, Nogara L, Blaauw B, Trifunovic A, et al. PERM1 interacts with the MICOS-MIB complex to connect the mitochondria and sarcolemma via ankyrin B.Nat Commun. 2021; 12:4900. doi: 10.1038/s41467-021-25185-3CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails March 14, 2023Vol 147, Issue 11 Advertisement Article InformationMetrics © 2023 American Heart Association, Inc.https://doi.org/10.1161/CIRCULATIONAHA.122.060173PMID: 36913499 Originally publishedMarch 13, 2023 KeywordsMICOSoxidative metabolismmitochondriapressure overloadPerm1PDF download Advertisement SubjectsHypertrophyRemodeling

Introduction: Troponin inhibitor3 ( TNNI3 ) is a thin-filament protein that regulates contraction of thick filaments. The role of the switch domain of TNNI3 (aa147-163), which interacts with the calcium-binding pocket of troponin C, is poorly defined. Pathogenic mutations to the switch domain cause restrictive cardiomyopathy in humans, but no therapies exist that address the underlying problem of this mutation at the sarcomeric level. Further, few models of genetic restrictive cardiomyopathy exist to aid in development of new therapies. Hypothesis: Substitution of alanine with valine at position 157 (A157V) in the switch domain of TNNI3 causes restrictive cardiomyopathy by blunting response to adrenergic stimulus. Methods: A known pathogenic mutation to the TNNI3 switch domain (A157V) was identified in a family of patients with cardiomyopathy and restrictive features. A mutant knock-in mouse homozygous for this mutation (A157V) was generated using CRISPR-Cas9 and used to elucidate the function of the switch domain. Results: Compared to wild type controls (WT), mutant A157V mice demonstrate significant restrictive features on invasive hemodynamics that worsen with age but do not show evidence of systolic dysfunction or hypertrophy on echocardiography. Heart size and myocyte cross-sectional area were significantly smaller in mutant A157V mice compared to WT controls. Molecular dynamics simulations revealed reduced TNNI3 activation in response to PKA-mediated phosphorylation at serine23/24. Isolated myocytes from A157V mice demonstrated impaired relaxation, lower peak systolic calcium and delayed reuptake of calcium into the sarcoplasmic reticulum compared to WT controls. Conclusions: The A157V mutation to the switch domain of TNNI3 , a critical regulatory domain that interacts with the calcium binding pocket of troponin C, causes diastolic dysfunction by impairing responsiveness to PKA-mediated phosphorylation of S23/24. This mouse model recapitulates the key restrictive features of human disease and could be used as a platform to study future targeted therapeutics for thin filament cardiomyopathy.

Normal contractile function of the heart depends on a constant and reliable production of ATP by cardiomyocytes. Dysregulation of cardiac energy metabolism can result in immature heart development and disrupt the ability of the adult myocardium to adapt to stress, potentially leading to heart failure. Further, restoration of abnormal mitochondrial function can have beneficial effects on cardiac dysfunction. Previously, we identified a novel protein termed Perm1 (PGC-1 and estrogen-related receptor (ERR)-induced regulator, muscle 1) that is enriched in skeletal and cardiac-muscle mitochondria and transcriptionally regulated by PGC-1 (peroxisome proliferator-activated receptor gamma coactivator 1) and ERR. The role of Perm1 in the heart is poorly understood and is studied here. We utilized cell culture, mouse models, and human tissue, to study its expression and transcriptional control, as well as its role in transcription of other factors. Critically, we tested Perm1's role in cardiomyocyte mitochondrial function and its ability to protect myocytes from stress-induced damage. Our studies show that Perm1 expression increases throughout mouse cardiogenesis, demonstrate that Perm1 interacts with PGC-1α and enhances activation of PGC-1 and ERR, increases mitochondrial DNA copy number, and augments oxidative capacity in cultured neonatal mouse cardiomyocytes. Moreover, we found that Perm1 reduced cellular damage produced as a result of hypoxia and reoxygenation-induced stress and mitigated cell death of cardiomyocytes. Taken together, our results show that Perm1 promotes mitochondrial biogenesis in mouse cardiomyocytes. Future studies can assess the potential of Perm1 to be used as a novel therapeutic to restore cardiac dysfunction induced by ischemic injury.

Vinculin, a mechanotransducer associated with both adherens junctions (AJ) and focal adhesions (FA) plays a central role in force transmission through these cell-cell and cell-substratum contacts. Here we describe the conditional knock out (KO) of vinculin in murine skin. Remarkably, we find that the loss of vinculin function results in the loss of bulge stem cell (BuSC) quiescence. We demonstrate that vinculin KO cells are impaired in force generation resulting in mechanically weak AJs. Mechanistically, vinculin functions by keeping α-catenin in a stretched conformation, which in turn regulates the retention of YAP1, another potent mechanotransducer and regulator of cell proliferation, to the junctions. Conditional KO of α-catenin specifically in the BuSCs further corroborates the importance of stable AJs in the maintenance of quiescence and stemness. Altogether, our data provides definitive mechanistic insights into the hitherto unexplored regulatory link between the mechanical stability of cell-junctions and the maintenance of BuSC quiescence.

RATIONALE:ZO-1 (Zonula occludens-1), a plasma membrane-associated scaffolding protein regulates signal transduction, transcription, and cellular communication. Global deletion of ZO-1 in the mouse is lethal by embryonic day 11.5. The function of ZO-1 in cardiac myocytes (CM) is largely unknown.OBJECTIVE:To determine the function of CM ZO-1 in the intact heart, given its binding to other CM proteins that have been shown instrumental in normal cardiac conduction and function.METHODS AND RESULTS:We generated ZO-1 CM-specific knockout (KO) mice using α-Myosin Heavy Chain-nuclear Cre (ZO-1cKO) and investigated physiological and electrophysiological function by echocardiography, surface ECG and conscious telemetry, intracardiac electrograms and pacing, and optical mapping studies. ZO-1cKO mice were viable, had normal Mendelian ratios, and had a normal lifespan. Ventricular morphometry and function were not significantly different between the ZO-1cKO versus control (CTL) mice, basally in young or aged mice, or even when hearts were subjected to hemodynamic loading. Atrial mass was increased in ZO-1cKO. Electrophysiological and optical mapping studies indicated high-grade atrioventricular (A-V) block in ZO-1cKO comparing to CTL hearts. While ZO-1-associated proteins such as vinculin, connexin 43, N-cadherin, and α-catenin showed no significant change with the loss of ZO-1, Connexin-45 and Coxsackie-adenovirus (CAR) proteins were reduced in atria of ZO-1cKO. Further, with loss of ZO-1, ZO-2 protein was increased significantly in ventricular CM in a presumed compensatory manner but was still not detected in the AV nodal myocytes. Importantly, the expression of the sodium channel protein NaV1.5 was altered in AV nodal cells of the ZO-1cKO versus CTL.CONCLUSIONS:ZO-1 protein has a unique physiological role in cardiac nodal tissue. This is in alignment with its known interaction with CAR and Cx45, and a new function in regulating the expression of NaV1.5 in AV node. Uniquely, ZO-1 is dispensable for function of the working myocardium.

Neutrophils are innate immune effector cells that traffic from the circulation to extravascular sites of inflammation. β2 integrins are important mediators of the processes involved in neutrophil recruitment. Although neutrophils express the cytoskeletal protein vinculin, they do not form mature focal adhesions. Here, we characterize the role of vinculin in β2 integrin-dependent neutrophil adhesion, migration, mechanosensing, and recruitment. We observe that knockout of vinculin attenuates, but does not completely abrogate, neutrophil adhesion, spreading, and crawling under static conditions. However, we also found that vinculin deficiency does not affect these behaviors in the presence of forces from fluid flow. In addition, we identify a role for vinculin in mechanosensing, as vinculin-deficient neutrophils exhibit attenuated spreading on stiff, but not soft, substrates. Consistent with these findings, we observe that in vivo neutrophil recruitment into the inflamed peritoneum of mice remains intact in the absence of vinculin. Together, these data suggest that while vinculin regulates some aspects of neutrophil adhesion and spreading, it may be dispensable for β2 integrin-dependent neutrophil recruitment in vivo .

Talin (Tln) is a component of muscle costameres that links integrins to other components of the cellular cytoskeleton and plays an important role in maintaining the cellular integrity of cardiac myocytes (CM). There are two talin genes, Tln1 and Tln2, expressed in the heart. Tln1 is ubiquitously expressed, and Tln2 is dominantly expressed in CM. In our previous study, we show that the global deletion of Tln2 in mice (T2KO) caused no structural or functional changes in the heart, presumably because CM Tln1 became up-regulated. However, we found that mice lacking both CM Tln1 and Tln2 exhibit cardiac dysfunction by 4 weeks (w) of age with 100% mortality by 6 months (m), showing Tln plays an essential role in cardiac development and in maintaining cardiac function. In this study, we produced a tamoxifen (Tamo)-inducible mouse model in which Tln1 could be explicitly reduced in the adult CM (T1icKO), and then generate T1icKO:T2KO (T1/2dKO), so that the function of Tln could be assessed in the postnatal heart. T2KO and Tln1/2dKO mice were injected with Tamo at 8w. Echocardiograms were performed to evaluate cardiac function up to 8w post-Tamo injection. While T2KO mice showed normal cardiac function, T1/2dKO exhibited a gradual decrease in function post-Tamo injection. At 8w post-Tamo injection, T1/2dKO mice showed cardiac hypertrophy, fibrosis, and heart failure. To understand the mechanism by which deletion CM talin leads to cardiac dysfunction, left ventricular tissue protein lysates from T2KO and T1/2dKO mice at 4w post-Tamo when cardiac function (echo) and structure were preserved in dKO. The protein lysates were subjected to quantitative mass spectrometry analysis. We found there are 1,100 proteins differentially expressed in T2KO and T1/2dKO hearts. Pathway analysis was performed, and the results showed that proteins involved in vesicle transport, protein folding, and innate immunity are most up-regulated in the T1/2dKO heart. Taken together, our results show that Tln is required for maintaining proper cardiac function in the adult heart. The deletion of Tln in CM results in the up-regulation of multiple intracellular pathways, and we are currently studying the role of each pathway in the pathogenesis of heart failure induced by CM Tln deletion.

Integrin receptors enable cells to sense and respond to their chemical and physical environment. As a class of membrane receptors, they provide a dynamic, tightly regulated link between the extracellular matrix or cellular counter-receptors and intracellular cytoskeletal and signaling networks. They enable transmission of mechanical force across the plasma membrane, and particularly for cardiomyocytes, may sense the mechanical load placed on cells. Talins and Kindlins are two families of FERM-domain proteins which bind the cytoplasmic tail of integrins, recruit cytoskeletal and signaling proteins involved in mechano-transduction, and those which synergize to activate integrins, allowing the integrins to physically change and bind to extracellular ligands. In this review, we will discuss the roles of talin and kindlin, particularly as integrin activators, with a focus on cardiac myocytes.

Thrombospondins (Thbs) are a family of five secreted matricellular glycoproteins in vertebrates that broadly affect cell-matrix interaction. While Thbs4 is known to protect striated muscle from disease by enhancing sarcolemmal stability through increased integrin and dystroglycan attachment complexes, here we show that Thbs3 antithetically promotes sarcolemmal destabilization by reducing integrin function, augmenting disease-induced decompensation. Deletion of Thbs3 in mice enhances integrin membrane expression and membrane stability, protecting the heart from disease stimuli. Transgene-mediated overexpression of α7β1D integrin in the heart ameliorates the disease predisposing effects of Thbs3 by augmenting sarcolemmal stability. Mechanistically, we show that mutating Thbs3 to contain the conserved RGD integrin binding domain normally found in Thbs4 and Thbs5 now rescues the defective expression of integrins on the sarcolemma. Thus, Thbs proteins mediate the intracellular processing of integrin plasma membrane attachment complexes to regulate the dynamics of cellular remodeling and membrane stability.

Vinculin is an essential component of cell adhesion complexes, where it regulates the strength and stability of adhesions. Whilst the role of vinculin in cell motility is well established, it remains unclear how vinculin contributes to other aspects of tissue function. Here we examine the role of vinculin in mammary epithelial cell phenotype. In these cells, correct adhesion to the extracellular matrix is essential for both the formation of polarised secretory acini and for the transcription of tissue-specific milk protein genes. We show that vinculin, through its interaction with talin, controls milk protein gene expression. However, vinculin is not required for the formation of polarised acini. This work reveals new roles for vinculin that are central to cellular differentiation, and for the ability of cells to interpret their extracellular microenvironment.

Mitochondria and oxidative metabolism are critical for maintaining cardiac muscle function. Research has shown that mitochondrial dysfunction is an important contributing factor to impaired cardiac function found in heart failure. By contrast, restoring defective mitochondrial function may have beneficial effects to improve cardiac function in the failing heart. Therefore, studying the regulatory mechanisms and identifying novel regulators for mitochondrial function could provide insight which could be used to develop new therapeutic targets for treating heart disease. Here, cardiac myocyte mitochondrial respiration is analyzed using a unique cell culture system. First, a protocol has been optimized to rapidly isolate and culture high viability neonatal mouse cardiomyocytes. Then, a 96-well format extracellular flux analyzer is used to assess the oxygen consumption rate of these cardiomyocytes. For this protocol, we optimized seeding conditions and demonstrated that neonatal mouse cardiomyocytes oxygen consumption rate can be easily assessed in an extracellular flux analyzer. Finally, we note that our protocol can be applied to a larger culture size and other studies, such as intracellular signaling and contractile function analysis.

Objective: Endurance exercise training remodels skeletal muscle, leading to increased mitochondrial content and oxidative capacity. How exercise entrains skeletal muscle signaling pathways to induce adaptive responses remains unclear. In past studies, we identified Perm1 (PGC-1 and ERR induced regulator, muscle 1) as an exercise-induced gene and showed that Perm1 overexpression elicits similar muscle adaptations as endurance exercise training. The mechanism of action and the role of Perm1 in exercise-induced responses are not known. In this study, we aimed to determine the pathway by which Perm1 acts as well as the importance of Perm1 for acute and long-term responses to exercise. Methods: We performed immunoprecipitation and mass spectrometry to identify Perm1 associated proteins, and validated Perm1 interactions with the Ca2+/calmodulin-dependent protein kinase II (CaMKII). We also knocked down Perm1 expression in gastrocnemius muscles of mice via AAV-mediated delivery of shRNA and assessed the impact of reduced Perm1 expression on both acute molecular responses to a single treadmill exercise bout and long-term adaptive responses to four weeks of voluntary wheel running training. Finally, we asked whether Perm1 levels are modulated by diet or diseases affecting skeletal muscle function. Results: We show that Perm1 associates with skeletal muscle CaMKII and promotes CaMKII activation. In response to an acute exercise bout, muscles with a knock down of Perm1 showed defects in the activation of CaMKII and p38 MAPK and blunted induction of regulators of oxidative metabolism. Following four weeks of voluntary training, Perm1 knockdown muscles had attenuated mitochondrial biogenesis. Finally, we found that Perm1 expression is reduced in diet-induced obese mice and in muscular dystrophy patients and mouse models. Conclusions: Our findings identify Perm1 as a muscle-specific regulator of exercise-induced signaling and Perm1 levels as tuners of the skeletal muscle response to exercise. The decreased Perm1 levels in states of obesity or muscle disease suggest that Perm1 may link pathological states to inefficient exercise responses. (C) 2019 The Authors. Published by Elsevier GmbH.

HomeCirculationVol. 139, No. 12Kindlin-2 Is Essential for Preserving Integrity of the Developing Heart and Preventing Ventricular Rupture Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBKindlin-2 Is Essential for Preserving Integrity of the Developing Heart and Preventing Ventricular Rupture Zhiyuan Zhang, MD, PhD, Yongxin Mu, PhD, Jianlin Zhang, PhD, Yangzhao Zhou, MD, Paola Cattaneo, PhD, Jennifer Veevers, PhD, Angela K. Peter, PhD, Ana Maria Manso, PhD, Kirk U. Knowlton, MD, Xinmin Zhou, MD, PhD, Sylvia M. Evans, PhD, Robert S. Ross, MD and Ju Chen, PhD Zhiyuan ZhangZhiyuan Zhang Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Department of Cardiovascular Surgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China (Z.Z., Y.Z., X.Z.). *Drs Z. Zhang and Y. Mu contributed equally. Search for more papers by this author , Yongxin MuYongxin Mu Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Department of Cardiovascular Surgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China (Z.Z., Y.Z., X.Z.). *Drs Z. Zhang and Y. Mu contributed equally. Search for more papers by this author , Jianlin ZhangJianlin Zhang Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Search for more papers by this author , Yangzhao ZhouYangzhao Zhou Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Search for more papers by this author , Paola CattaneoPaola Cattaneo National Research Council, Institute of Genetics and Biomedical Research, Milan Unit, Italy (P.C.). Humanitas Clinical and Research Center, Rozzano (MI), Italy (P.C.). Search for more papers by this author , Jennifer VeeversJennifer Veevers Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Search for more papers by this author , Angela K. PeterAngela K. Peter Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder (A.K.P.). Search for more papers by this author , Ana Maria MansoAna Maria Manso Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Veterans Administration Healthcare, Medicine/Cardiology, San Diego, CA (A.M.M., R.S.R.). Search for more papers by this author , Kirk U. KnowltonKirk U. Knowlton Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Intermountain Heart Institute Intermountain Medical Center, Salt Lake City, UT (K.U.K.). Search for more papers by this author , Xinmin ZhouXinmin Zhou Department of Cardiovascular Surgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China (Z.Z., Y.Z., X.Z.). Search for more papers by this author , Sylvia M. EvansSylvia M. Evans Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Search for more papers by this author , Robert S. RossRobert S. Ross Ju Chen, PhD, Department of Medicine-Cardiology, University of California San Diego, 9500 Gilman Dr, Mail Code 0613-C, La Jolla, CA 92093-0613. Email E-mail Address: [email protected] Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Veterans Administration Healthcare, Medicine/Cardiology, San Diego, CA (A.M.M., R.S.R.). Search for more papers by this author and Ju ChenJu Chen Ju Chen, PhD, Department of Medicine-Cardiology, University of California San Diego, 9500 Gilman Dr, Mail Code 0613-C, La Jolla, CA 92093-0613. Email E-mail Address: [email protected] Department of Medicine-Cardiology, University of California San Diego, La Jolla (Z.Z., Y.M., J.Z., Y.Z., J.V., A.K.P., A.M.M., K.U.K., S.M.E., R.S.R., J.C.). Search for more papers by this author Originally published18 Mar 2019https://doi.org/10.1161/CIRCULATIONAHA.118.038383Circulation. 2019;139:1554–1556Myocardial wall integrity is essential for normal heart development and for preservation of normal postnatal cardiac function. Congenital ventricular aneurysms can lead to rupture, heart failure, or heart rhythm disturbance.1 Weakened myocardial wall can also result in post–myocardial infarction rupture, frequently leading to death.Kindlin-2 is the only Kindlin family member expressed in the mammalian heart. Kindlin-2 regulates integrin activation2 and integrin-independent pathways.3 A potential role for Kindlin-2 in developing cardiomyocytes, and whether any requirement for Kindlin-2 reflects an integrin-dependent or integrin-independent role for Kindlin-2, remains to be addressed. Accordingly, we generated Kindlin-2 cardiomyocyte-specific knockout (KN2-cKO) mice by crossing floxed Kindlin-2 mice (Kindlin-2f/f)3 with TnT-Cre mice.4 KN2-cKOs began to die at embryonic day 11.5 (E11.5), and no viable KN2-cKOs were observed at E12.5. No morphological differences were evident between KN2-cKO and control hearts at E10.5. However, morphological abnormalities were evident in E11.5 KN2-cKO hearts (Figure, A and B). Histological analysis revealed hemorrhage within the E11.5 KN2-cKO myocardial wall of all 9 embryos analyzed (Figure B). Results from immunostaining for α-actinin (cardiomyocytes) and CD31 (endothelium) revealed that, at E10.5, KN2-cKO hearts were indistinguishable from controls. In contrast, at E11.5, KN2-cKO hearts displayed discontinuity of α-actinin–positive myocardium that was replaced with CD31-positive thrombi (Figure C).Download figureDownload PowerPointFigure. Kindlin-2/β1 integrin pathway in cardiomyocytes is essential for preserving the integrity of the developing heart and preventing ventricular rupture.A, Whole-mount microscopic assessment of control (ctrl) and cardiomyocyte-specific knockout (KN2-cKO) embryos (left lateral view) at embryonic day (E) 10.5, E11.5, and E12.5. Arrow indicates pericardial effusion. B, Top, Microscopic assessment of ctrl and KN2-cKO hearts at E10.5 and E11.5. Middle, Histological evaluation with hematoxylin and eosin staining of transverse sections from hearts. Bottom, High-magnification views of boxed areas. Arrow indicates rupture site. C, Immunomicroscopic analysis of transverse sections of hearts of ctrl and KN2-cKO embryos at E10.5 and E11.5, staining for sarcomeric α-actinin (red), CD31 (green), and DAPI (blue). Arrow indicates rupture site. D, Immunomicroscopic analysis of organization and distribution of fibronectin, laminin, and perlecan in hearts of ctrls and KN2-cKOs at E10.5, staining for fibronectin/laminin/ perlecan (green), sarcomeric α-actinin (red), and DAPI (blue). Arrows point to the well-organized layer of fibronectin, laminin, and perlecan in ctrl hearts, whereas arrowheads indicate the loss of well-delineated fibronectin, laminin, and perlecan on the epicardial surface of the compact myocardial layer. Transmission electron microscopy (TEM) analysis confirmed the loss of basement membrane in KN2-cKO hearts. Arrows point to well-formed basement membrane in ctrl hearts, whereas arrow heads point to severely diminished membrane in KN2-cKO hearts at E11.0. E, Western blot analysis of β1 integrin in ctrl and KN2-cKO hearts at E10.5. GAPDH served as a loading control (Top left). The graphs show corresponding quantitative densitometric analysis where protein pixel density is normalized to the level of GAPDH (bottom left). n=4. Stainings for total β1 integrin (green), sarcomeric α-actinin (red), and DAPI (blue) are shown (middle). Stainings for ligand-bound confirmation/activated form of β1 integrin using the activation-specific antibody 9EG7 (green), sarcomeric α-actinin (red), and DAPI (blue) are shown (right). F, Immunomicroscopic analysis of ctrl and INT-cKO mouse hearts at E11.5 to E13.5, staining for β1 integrin (green), sarcomeric α-actinin (red), and DAPI (blue). G, Immunomicroscopic analysis of the organization and distribution of fibronectin, laminin, and perlecan in the hearts of ctrl and INT-cKO at E10.5, staining for fibronectin/laminin/ perlecan (green), sarcomeric α-actinin (red), and DAPI (blue). Arrows point to the well-organized layer of fibronectin, laminin, and perlecan in ctrl hearts, whereas arrowheads indicate the loss of well-delineated fibronectin, laminin, and perlecan on the epicardial surface of the compact myocardial layer. TEM analysis confirmed the loss of basement membrane in INT-cKO hearts. Arrows point to well-formed basement membrane in ctrl hearts, whereas arrowheads point to severely diminished basement membrane in INT-cKO hearts at E11.0. H, Real-time PCR analysis of relative mRNA levels of target genes of interest in ctrl and KN2-cKO hearts at E10.5. Data are normalized to corresponding 18S rRNA levels, and cKO values are expressed as fold change vs ctrls. n=3. All genes tested were not statistically different between control and knockout samples, when evaluated using Student t test (P>0.05). I, RNA-sequencing data for (i) yap-related genes, (ii) TGFβ-related genes, and (iii) sox9 in ctrl and KN2-cKO hearts at E10.5. n=3. No genes were expressed differentially between ctrl and KN2-cKO samples when evaluated using Student t test (P>0.05). DAPI indicates 4′,6-diamidino-2-phenylindole; PCR, polymerase chain reaction; and TGFβ, transforming growth factor β.Because ablation of the basement membrane protein, perlecan, also leads to embryonic heart rupture,5 we investigated extracellular matrix organization. Indeed, extracellular matrix components, fibronectin, laminin, and perlecan were severely reduced in compact myocardium of KN2-cKO hearts (Figure D). Transmission electron microscopy analysis confirmed the loss of basement membrane in KN2-cKO hearts (Figure D). We next investigated how the loss of Kindlin-2 from cardiomyocytes might affect integrin abundance and localization. RNA-sequencing data from isolated embryonic cardiomyocytes revealed that β1 integrin was the dominant β isoform (reads per kilobase per million mapped reads ≈1000), with β3 and β5 also being expressed, but at much lower levels (reads per kilobase per million mapped reads ≈30). Thus, we focused our attention on β1 integrin. Western blot analysis revealed that the level of β1 integrin was slightly decreased in E10.5 KN2-cKO hearts in comparison with controls, although immunomicroscopic analysis showed no evident differences between KN2-cKO and control samples (Figure E). We then evaluated integrin activation using an antibody (9EG7) that detects ligand-bound β1 integrin, a state judged to represent the activated form. β1 integrin activation was dramatically reduced in KN2-cKO hearts versus controls (Figure E), indicating that Kindlin-2 was required for β1 integrin activation in cardiomyocytes.To investigate whether disruption of β1 integrin activation might account for the loss of myocardial integrity and hemorrhage observed in KN2-cKO embryos, we generated β1 integrinf/–;TnT-Cre mice (INT-cKO). INT-cKO embryos began to die at E13.5 with hemorrhage evident in the chest region, and no viable INT-cKO embryos were observed at E14.5. Like KN2-cKO hearts, discontinuity of the compact layer of the myocardium was clearly evident, with hemorrhage through the myocardial wall into the pericardium of INT-cKO embryos (Figure F). Another striking similarity between KN2-cKO and INT-cKO embryos included severely reduced expression of extracellular matrix proteins fibronectin, laminin, and perlecan in the developing heart (Figure G). Potential compensation by β3 or β5 integrin for the loss of β1 integrin may explain why myocardial rupture and subsequent embryonic lethality occurred ≈2 days later in INT-cKO embryos in comparison with KN2-cKO embryos.In addition to its integrin-dependent role, Kindlin-2 can also play a role in transforming growth factor β pathway function, and can regulate expression of sox9 and yap/taz.3 Thus, we evaluated these pathways in our KN2-cKO mice. Real-time polymerase chain reaction and RNA-sequencing analyses were performed and showed that neither expression of yap1/taz, sox9, or target genes of the transforming growth factor β pathway was affected by the loss of Kindlin-2 (Figure H and I).In summary, our data demonstrate a previously unknown essential role for a Kindlin-2/integrin pathway in extracellular matrix organization and myocardial integrity of the midgestation heart. These results critically provide a new understanding of basic processes of cardiogenesis, but also have potential implications for postnatal heart disease, because the integrity of the myocardium is essential for both normal heart development and for the preservation of normal postnatal cardiac function, prevention of cardiomyopathy, and, most dramatically, protection from myocardial wall rupture from congenital or postnatal causes.All procedures were performed in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and approved by the Institutional Animal Care and Use Committee of the University of California, San Diego.Sources of FundingDrs Chen, Evans, and Ross are supported by grants from the National Institutes of Health. Dr Chen is the American Heart Association (AHA) Endowed Chair in Cardiovascular Research. Dr Zhang is supported by Hunan Provincial Natural Science Foundation of China (2018JJ3722).DisclosuresNone.Footnotes*Drs Z. Zhang and Y. Mu contributed equally.https://www.ahajournals.org/journal/circData sharing: RNAseq raw data can be accessed at GEO using GSE123280. Other data, analytic methods, and study materials will be/have been made available to other researchers for purposes of reproducing results or replicating procedures.Ju Chen, PhD, Department of Medicine-Cardiology, University of California San Diego, 9500 Gilman Dr, Mail Code 0613-C, La Jolla, CA 92093-0613. Email [email protected]eduRobert S. Ross, MD, Department of Medicine-Cardiology, University of California San Diego, 9500 Gilman Dr, Mail Code 0613-C, La Jolla, CA 92093-0613. Email [email protected]eduReferences1. Ohlow MA, von Korn H, Lauer B. Characteristics and outcome of congenital left ventricular aneurysm and diverticulum: analysis of 809 cases published since 1816.Int J Cardiol. 2015; 185:34–45. doi: 10.1016/j.ijcard.2015.03.050CrossrefMedlineGoogle Scholar2. Montanez E, Ussar S, Schifferer M, Bösl M, Zent R, Moser M, Fässler R. Kindlin-2 controls bidirectional signaling of integrins.Genes Dev. 2008; 22:1325–1330. doi: 10.1101/gad.469408CrossrefMedlineGoogle Scholar3. Wu C, Jiao H, Lai Y, Zheng W, Chen K, Qu H, Deng W, Song P, Zhu K, Cao H, Galson DL, Fan J, Im HJ, Liu Y, Chen J, Chen D, Xiao G. Kindlin-2 controls TGF-β signalling and Sox9 expression to regulate chondrogenesis.Nat Commun. 2015; 6:7531. doi: 10.1038/ncomms8531CrossrefMedlineGoogle Scholar4. Jiao K, Kulessa H, Tompkins K, Zhou Y, Batts L, Baldwin HS, Hogan BL. An essential role of Bmp4 in the atrioventricular septation of the mouse heart.Genes Dev. 2003; 17:2362–2367. doi: 10.1101/gad.1124803CrossrefMedlineGoogle Scholar5. Costell M, Gustafsson E, Aszódi A, Mörgelin M, Bloch W, Hunziker E, Addicks K, Timpl R, Fässler R. Perlecan maintains the integrity of cartilage and some basement membranes.J Cell Biol. 1999; 147:1109–1122.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Peng D, Fu M, Wang M, Wei Y and Wei X (2022) Targeting TGF-β signal transduction for fibrosis and cancer therapy, Molecular Cancer, 10.1186/s12943-022-01569-x, 21:1, Online publication date: 1-Dec-2022. Gao H, Zhou L, Zhong Y, Ding Z, Lin S, Hou X, Zhou X, Shao J, Yang F, Zou X, Cao H and Xiao G (2022) Kindlin-2 haploinsufficiency protects against fatty liver by targeting Foxo1 in mice, Nature Communications, 10.1038/s41467-022-28692-z, 13:1, Online publication date: 1-Dec-2022. Chen S, Wu X, Lai Y, Chen D, Bai X, Liu S, Wu Y, Chen M, Lai Y, Cao H, Shao Z and Xiao G (2022) Kindlin-2 inhibits Nlrp3 inflammasome activation in nucleus pulposus to maintain homeostasis of the intervertebral disc, Bone Research, 10.1038/s41413-021-00179-5, 10:1, Online publication date: 1-Dec-2022. Wu X, Lai Y, Chen S, Zhou C, Tao C, Fu X, Li J, Tong W, Tian H, Shao Z, Liu C, Chen D, Bai X, Cao H and Xiao G (2022) Kindlin-2 preserves integrity of the articular cartilage to protect against osteoarthritis, Nature Aging, 10.1038/s43587-021-00165-w, 2:4, (332-347), Online publication date: 1-Apr-2022. Bang M, Bogomolovas J and Chen J (2022) Understanding the molecular basis of cardiomyopathy, American Journal of Physiology-Heart and Circulatory Physiology, 10.1152/ajpheart.00562.2021, 322:2, (H181-H233), Online publication date: 1-Feb-2022. Wang W, Rana P, Alkrekshi A, Bialkowska K, Markovic V, Schiemann W, Plow E, Pluskota E and Sossey-Alaoui K (2022) Targeted Deletion of Kindlin-2 in Mouse Mammary Glands Inhibits Tumor Growth, Invasion, and Metastasis Downstream of a TGF-β/EGF Oncogenic Signaling Pathway, Cancers, 10.3390/cancers14030639, 14:3, (639) Wu X, Qu M, Gong W, Zhou C, Lai Y and Xiao G (2022) Kindlin-2 deletion in osteoprogenitors causes severe chondrodysplasia and low-turnover osteopenia in mice, Journal of Orthopaedic Translation, 10.1016/j.jot.2021.08.005, 32, (41-48), Online publication date: 1-Jan-2022. Qin L, Fu X, Ma J, Lin M, Zhang P, Wang Y, Yan Q, Tao C, Liu W, Tang B, Chen D, Bai X, Cao H and Xiao G (2021) Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes, Communications Biology, 10.1038/s42003-021-01950-4, 4:1, Online publication date: 1-Dec-2021. Gao H, Zhong Y, Ding Z, Lin S, Hou X, Tang W, Zhou X, Zou X, Shao J, Yang F, Bai X, Liu C, Cao H and Xiao G (2021) Pinch Loss Ameliorates Obesity, Glucose Intolerance, and Fatty Liver by Modulating Adipocyte Apoptosis in Mice, Diabetes, 10.2337/db21-0392, 70:11, (2492-2505), Online publication date: 1-Nov-2021. Chen K, Guo L and Wu C (2021) How signaling pathways link extracellular mechano‐environment to proline biosynthesis: A hypothesis, BioEssays, 10.1002/bies.202100116, 43:9, (2100116), Online publication date: 1-Sep-2021. Chen D, Zhang C, Chen J, Yang M, Afzal T, An W, Maguire E, He S, Luo J, Wang X, Zhao Y, Wu Q and Xiao Q (2020) miRNA ‐200c‐ 3p promotes endothelial to mesenchymal transition and neointimal hyperplasia in artery bypass grafts , The Journal of Pathology, 10.1002/path.5574, 253:2, (209-224), Online publication date: 1-Feb-2021. 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March 19, 2019Vol 139, Issue 12 Advertisement Article InformationMetrics © 2019 American Heart Association, Inc.https://doi.org/10.1161/CIRCULATIONAHA.118.038383PMID: 30883226 Originally publishedMarch 18, 2019 Keywordsheartextracellular matrixintegrinmyocardiumaneurysmbasement membranePDF download Advertisement SubjectsBasic Science ResearchCell Signaling/Signal TransductionMyocardial Biology

Dilated cardiomyopathy (DCM) is a leading cause of morbidity and mortality worldwide; yet how genetic variation and environmental factors impact DCM heritability remains unclear. Here, we report that compound genetic interactions between DNA sequence variants contribute to the complex heritability of DCM. By using genetic data from a large family with a history of DCM, we discovered that heterozygous sequence variants in the TROPOMYOSIN 1 (TPM1) and VINCULIN (VCL) genes cose-gregate in individuals affected by DCM. In vitro studies of patient-derived and isogenic human-pluripotent-stem-cell-derived cardio-myocytes that were genome-edited via CRISPR to create an allelic series of TPM1 and VCL variants revealed that cardiomyocytes with both TPM1 and VCL variants display reduced contractility and sarcomeres that are less organized. Analyses of mice genetically engineered to harbour these human TPM1 and VCL variants show that stress on the heart may also influence the variable penetrance and expressivity of DCM-associated genetic variants in vivo. We conclude that compound genetic variants can interact combinatorially to induce DCM, particularly when influenced by other disease-provoking stressors.

BACKGROUND:Inflammation is associated with cardiac remodeling and heart failure, but how it is initiated in response to nonischemic interventions in the absence of cell death is not known. We tested the hypothesis that activation of Ca2+/calmodulin-dependent protein kinase II δ (CaMKIIδ) in cardiomyocytes (CMs) in response to pressure overload elicits inflammatory responses leading to adverse remodeling.METHODS:Mice in which CaMKIIδ was selectively deleted from CMs (cardiac-specific knockout [CKO]) and floxed control mice were subjected to transverse aortic constriction (TAC). The effects of CM-specific CaMKIIδ deletion on inflammatory gene expression, inflammasome activation, macrophage accumulation, and fibrosis were assessed by quantitative polymerase chain reaction, histochemistry, and ventricular remodeling by echocardiography.RESULTS:TAC induced increases in cardiac mRNA levels for proinflammatory chemokines and cytokines in ≤3 days, and these responses were significantly blunted when CM CaMKIIδ was deleted. Apoptotic and necrotic cell death were absent at this time. CMs isolated from TAC hearts mirrored these robust increases in gene expression, which were markedly attenuated in CKO. Priming and activation of the NOD-like receptor pyrin domain-containing protein 3 inflammasome, assessed by measuring interleukin-1β and NOD-like receptor pyrin domain-containing protein 3 mRNA levels, caspase-1 activity, and interleukin-18 cleavage, were increased at day 3 after TAC in control hearts and in CMs isolated from these hearts. These responses were dependent on CaMKIIδ and associated with activation of Nuclear Factor-kappa B and reactive oxygen species. Accumulation of macrophages observed at days 7 to 14 after TAC was diminished in CKO and, by blocking Monocyte Chemotactic Protein-1 signaling, deletion of CM Monocyte Chemotactic Protein-1 or inhibition of inflammasome activation. Fibrosis was also attenuated by these interventions and in the CKO heart. Ventricular dilation and contractile dysfunction observed at day 42 after TAC were diminished in the CKO. Inhibition of CaMKII, Nuclear Factor-kappa B, inflammasome, or Monocyte Chemotactic Protein-1 signaling in the first 1 or 2 weeks after TAC decreased remodeling, but inhibition of CaMKII after 2 weeks did not.CONCLUSIONS:Activation of CaMKIIδ in response to pressure overload triggers inflammatory gene expression and activation of the NOD-like receptor pyrin domain-containing protein 3 inflammasome in CMs. These responses provide signals for macrophage recruitment, fibrosis, and myocardial dysfunction in the heart. Our work suggests the importance of targeting early inflammatory responses induced by CM CaMKIIδ signaling to prevent progression to heart failure.