Nerve growth factor transfer from cardiomyocytes to innervating sympathetic neurons activates TrkA receptors at the neuro-cardiac junction
Author(s)
Type
Journal Article
Abstract
Sympathetic neurons densely innervate the myocardium with non-random topology and establish structured contacts (i.e. neuro-cardiac junctions, NCJ) with cardiomyocytes, allowing synaptic intercellular communication. Establishment of heart innervation is regulated by molecular mediators released by myocardial cells. The mechanisms underlying maintenance of cardiac innervation in the fully developed heart, are, however, less clear. Notably, several cardiac diseases, primarily affecting cardiomyocytes, are associated with sympathetic denervation, supporting the hypothesis that retrograde 'cardiomyocyte-to-sympathetic neuron' communication is essential for heart cellular homeostasis. We aimed to determine whether cardiomyocytes provide nerve growth factor (NGF) to sympathetic neurons, and the role of the NCJ in supporting such retrograde neurotrophic signalling. Immunofluorescence on murine and human heart slices shows that NGF and its receptor, tropomyosin-receptor-kinase-A, accumulate, respectively, in the pre- and post-junctional sides of the NCJ. Confocal immunofluorescence, scanning ion conductance microscopy and molecular analyses, in co-cultures, demonstrate that cardiomyocytes feed NGF to sympathetic neurons, and that this mechanism requires a stable intercellular contact at the NCJ. Consistently, cardiac fibroblasts, devoid of NCJ, are unable to sustain SN viability. ELISA assay and competition binding experiments suggest that this depends on the NCJ being an insulated microenvironment, characterized by high [NGF]. In further support, real-time imaging of tropomyosin-receptor-kinase-A vesicle movements demonstrate that efficiency of neurotrophic signalling parallels the maturation of such structured intercellular contacts. Altogether, our results demonstrate the mechanisms which link sympathetic neuron survival to neurotrophin release by directly innervated cardiomyocytes, conceptualizing sympathetic neurons as cardiomyocyte-driven heart drivers. KEY POINTS: CMs are the cell source of nerve growth factor (NGF), required to sustain innervating cardiac SNs; NCJ is the place of the intimate liaison, between SNs and CMs, allowing on the one hand neurons to peremptorily control CM activity, and on the other, CMs to adequately sustain the contacting, ever-changing, neuronal actuators; alterations in NCJ integrity may compromise the efficiency of 'CM-to-SN' signalling, thus representing a potentially novel mechanism of sympathetic denervation in cardiac diseases.
Date Issued
2022-06-15
Date Acceptance
2022-03-28
Citation
The Journal of Physiology, 2022, 600 (12), pp.2853-2875
ISSN
0022-3751
Publisher
Wiley
Start Page
2853
End Page
2875
Journal / Book Title
The Journal of Physiology
Volume
600
Issue
12
Copyright Statement
© 2022 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Sponsor
British Heart Foundation
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/35413134
Grant Number
RG/17/13/33173
Subjects
Animals
Heart Diseases
Humans
Mice
Myocytes, Cardiac
Nerve Growth Factor
Neurons
Receptor, trkA
Sympathetic Nervous System
Tropomyosin
cardiac sympathetic neurons
cardiomyocytes
nerve growth factor
nerve growth factor receptor
neuro-cardiac junction
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2022-04-12