TGF-β1 affects cell-cell adhesion in the heart in an NCAM1-dependent mechanism
Introduction
Heart failure is a complex disease that results from the impairment of cardiac muscle function and often develops as a consequence of chronic neurohormonal and mechanical stress. While select heart failure treatments are available to reduce neuroendocrine signaling, such therapies do not prevent death and only mildly extend lifespan [1]. Hence, a better understanding of the molecular mechanisms underlying cardiac dysfunction is needed to aid in the development of new treatments that extend beyond neuroendocrine modulation.
The diseased heart is associated with remodeling of the intercalated discs (ID), structures responsible for transmission of contractile force between cardiomyocytes [2]. Proper organization of intercalated discs is necessary to maintain normal cell-cell interactions between myocytes and therefore preserve cardiac function [3]. Intercalated discs are composed of adherens junctions, desmosomes, and gap junctions [4]. The classical adhesion receptor present in the adherens junctions and desmosomes is composed of cadherins. The extracellular domain of cadherins promotes homophilic interactions that mediate strong myocyte-myocyte adhesion and allow proper maintenance of tissue structure [5]. In addition to cadherins, other receptors are targeted to the intercalated discs and regulate cardiomyocytes' coupling. Specifically, connexin proteins are key components of gap junctions, structures specialized in intercellular electric coupling [6]. In the past years it has become clear that intercalated discs are dynamic structures that are a target of complex signaling events that can alter their composition and compromise their function during disease states. Indeed, mislocalization of intercalated disc proteins is observed in heart failure and contributes to cardiac dysfunction [7]. Also, numerous mutations in intercalated disc proteins have been described, resulting in alterations to intercalated disc structure and consequently increasing susceptibility to deterioration of heart pump function [8].
During chronic stress or following insults (i.e. myocardial infarction or cardiotropic viral infection) complex signaling events perturb the homeostasis of the heart [9]. During these injury conditions secreted molecules coordinate the response of the heart to stress [10]. How this response results in disruption of cell adhesion in cardiomyocytes and overall dysfunction is not clear. A master regulator of tissue stress responses is Transforming Growth Factor beta 1 (TGFβ1) [11]. Activation of TGFβ1 is observed in the injured heart and a direct role of TGFβ1 in affecting cardiomyocytes function post-stress has been proven by Koitabashi and colleagues using genetic mouse models of cardiomyocyte-specific deletion of TGFβ1 receptors [12]. However, attempts to generate gain-of-function mouse models recapitulating the pathologic effects of TGFβ1 in the myocardium have been challenging, likely because TGFβ1 activation is tightly regulated and overexpression per se is typically not sufficient to increase its activity. Indeed, TGFβ1 is secreted as part of a complex with two other polypeptides, the latent TGFβ1 binding protein (LTBP) and the latency-associated peptide (LAP), together making up the latency complex [13], [14]. Attachment of TGFβ1 to the latency complex occurs through disulfide bonds that prevent the release of active TGFβ1 and therefore limit TGFβ1 bioavailability [14]. In 2000, Nakajima and colleagues successfully generated a mouse model expressing a mutant form of TGFβ1 (cysteine-to-serine substitution at residue 33) showing increased TGFβ1 activity in the heart, but not sufficient to uncover a ventricular phenotype [15]. These results have left an unmet need to fully understand the role of TGFβ1 signaling in ventricular cardiomyocyte dysfunction.
Here we adopted a mouse model of active TGFβ1 that mimics the degree of TGFβ1 activation observed in cardiomyopathy and we report a novel mechanism of TGFβ1-mediated ventricular dysfunction through a pathway dependent on Neural Adhesion Molecule 1 (NCAM1) to facilitate defective cardiomyocyte adhesion.
Section snippets
Procurement of human heart samples
The studies on human heart tissue were performed under the guidelines of the Declaration of Helsinki, with oversight by the Institutional Review Boards at The Ohio State University (protocol no. 2012H0197). Failing heart samples were obtained from patients who were diagnosed with end-stage heart failure and were receiving a heart transplant at The Ohio State University Wexner Medical Center. Non-failing hearts were obtained in collaboration with the Lifeline of Ohio Organ Procurement program
TGFβ1 activation induces ventricular dysfunction
TGFβ1 is induced in the injured heart and is considered a central player in cardiac diseases [17], [23]. Indeed, we observed increase in TGFβ1 activity in human failing hearts by ELISA (Fig. 1A). We have also found that cardiomyocytes are a source for TGFβ1 in human failing myocardium (Supplemental Fig. 1A and B). To mimic the TGFβ1 activation occurring during cardiomyopathies and to study the direct mechanistic role of TGFβ1 in cardiomyocytes we have adopted a transgenic mouse model for
Discussion
The TGFβ1 signaling pathway has been recognized as critical in the context of stress responses as well as in the development of multiple organ systems, including the heart [27]. The importance of understanding how TGFβ1 exerts its downstream action is demonstrated by the fact that perturbation of TGFβ1 signaling is known to occur in disease states in the heart and beyond. Also, genetic mutations affecting TGFβ1 activation are a primary cause of disease or act as disease modifiers in both
Acknowledgements
The authors would like to thank: Susan Montgomery, Erin Bumgardner, and Emily Jarvis for their help in consenting the patients for this study; Abraham Zawodni (Lifeline of Ohio) for help with obtaining clinical correlates for the donor hearts; Nathaniel Murphy for help with mouse phenotyping; Dr. Patricia Maness (UNC-Chapel Hill) for providing Ncam1 plasmids.
Sources of funding
This work was supported by grants from the NIHR00HL121284 and R01HL136951 (to F.A.), R00HL116778 (to M.A.A.), R01HL113084 (to P.M.L.J.), T32GM068412 (to J.M.P.).
Disclosures
None.
References (38)
- et al.
Three-dimensional structure of the intercalated disc reveals plicate domain and gap junction remodeling in heart failure
Biophys. J.
(2015) The extracellular matrix and transforming growth factor-beta1: tale of a strained relationship
Matrix Biol.
(2015)- et al.
Latent TGF-beta-binding proteins
Matrix Biol.
(2015) - et al.
NCAM(CD56) and RUNX1(AML1) are up-regulated in human ischemic cardiomyopathy and a rat model of chronic cardiac ischemia
Am. J. Pathol.
(2003) - et al.
The 140-kD isoform of CD56 (NCAM1) directs the molecular pathogenesis of ischemic cardiomyopathy
Am. J. Pathol.
(2013) - et al.
Regulation of neural cell adhesion molecule and L1 by the transforming growth factor-beta superfamily. Selective effects of the bone morphogenetic proteins
J. Biol. Chem.
(1994) - et al.
Heart failure as an inflammatory condition: potential role for androgens as immune modulators
Eur. J. Heart Fail.
(2002) - et al.
Mechanotransduction in cardiac hypertrophy and failure
Circ. Res.
(2015) - et al.
Refining the molecular organization of the cardiac intercalated disc
Cardiovasc. Res.
(2017) - et al.
Cadherin adhesion: mechanisms and molecular interactions
Handb. Exp. Pharmacol.
(2004)
Gap junctions - guards of excitability
Biochem. Soc. Trans.
Alterations in cell adhesion proteins and cardiomyopathy
World J. Cardiol.
Arrhythmogenic cardiomyopathy: a disease of intercalated discs
Cell Tissue Res.
Molecular pathways underlying cardiac remodeling during pathophysiological stimulation
Circulation
Adult mouse epicardium modulates myocardial injury by secreting paracrine factors
J. Clin. Invest.
TGF-beta signaling and the fibrotic response
FASEB J.
Pivotal role of cardiomyocyte TGF-beta signaling in the murine pathological response to sustained pressure overload
J. Clin. Invest.
Atrial but not ventricular fibrosis in mice expressing a mutant transforming growth factor-beta(1) transgene in the heart
Circ. Res.
Reengineering inducible cardiac-specific transgenesis with an attenuated myosin heavy chain promoter
Circ. Res.
Cited by (28)
Cardiac-derived TGF-β1 confers resistance to diet-induced obesity through the regulation of adipocyte size and function
2021, Molecular MetabolismCitation Excerpt :In the heart, TGF-β1 is sufficient to drive dysfunction and single cell analysis revealed ubiquitous expression of its receptors [13–15]. TGF-β1 is activated in response to cardiac injuries such as pressure overload-induced remodeling as well as in ischemic heart disease [13,14]. However, the impact of this growth factor as a systemic messenger for the heart has not been recognized previously.
CTGF/CCN2 is an autocrine regulator of cardiac fibrosis
2018, Journal of Molecular and Cellular CardiologyCitation Excerpt :As an example, members of the TGFβ family of growth factors have been extensively characterized for their ability to stimulate myofibroblast (pro-fibrotic) phenotypes both in vitro and in vivo [5]. In the heart, we have found that upregulation of TGFβ1 is sufficient to drive fibrosis, cardiac dysfunction, and mortality in a murine transgenic model [6, 7]. However, because of the pleiotropic effects of TGFβ1 and its critical functions not only in stress-responses but also in the maintenance of homeostasis, therapeutically targeting TGFβ1 is complicated and carries the risk for important adverse effects.
Proteomic study of left ventricle and cortex in rats after myocardial infarction
2024, Scientific ReportsEngineering a conduction-consistent cardiac patch with graphene oxide modified butterfly wings and human pluripotent stem cell-derived cardiomyocytes
2023, Bioengineering and Translational MedicineAssociation between Cardiovascular Response and Inflammatory Cytokines in Non-Small Cell Lung Cancer Patients
2023, Journal of Cardiovascular Development and Disease