Infantile restrictive cardiomyopathy: cTnI-R170G/W impair the interplay of sarcomeric proteins and the integrity of thin filaments.
Actins
/ metabolism
Amino Acid Substitution
Animals
Calcium
/ metabolism
Cardiomyopathy, Restrictive
/ genetics
Carrier Proteins
/ chemistry
Child, Preschool
Guinea Pigs
Humans
Microscopy, Electron
Models, Biological
Myocardium
/ metabolism
Protein Binding
Sarcomeres
/ metabolism
Tropomyosin
/ metabolism
Troponin I
/ genetics
Journal
PloS one
ISSN: 1932-6203
Titre abrégé: PLoS One
Pays: United States
ID NLM: 101285081
Informations de publication
Date de publication:
2020
2020
Historique:
received:
16
11
2019
accepted:
31
01
2020
entrez:
18
3
2020
pubmed:
18
3
2020
medline:
17
6
2020
Statut:
epublish
Résumé
TNNI3 encoding cTnI, the inhibitory subunit of the troponin complex, is the main target for mutations leading to restrictive cardiomyopathy (RCM). Here we investigate two cTnI-R170G/W amino acid replacements, identified in infantile RCM patients, which are located in the regulatory C-terminus of cTnI. The C-terminus is thought to modulate the function of the inhibitory region of cTnI. Both cTnI-R170G/W strongly enhanced the Ca2+-sensitivity of skinned fibres, as is typical for RCM-mutations. Both mutants strongly enhanced the affinity of troponin (cTn) to tropomyosin compared to wildtype cTn, whereas binding to actin was either strengthened (R170G) or weakened (R170W). Furthermore, the stability of reconstituted thin filaments was reduced as revealed by electron microscopy. Filaments containing R170G/W appeared wavy and showed breaks. Decoration of filaments with myosin subfragment S1 was normal in the presence of R170W, but was irregular with R170G. Surprisingly, both mutants did not affect the Ca2+-dependent activation of reconstituted cardiac thin filaments. In the presence of the N-terminal fragment of cardiac myosin binding protein C (cMyBPC-C0C2) cooperativity of thin filament activation was increased only when the filaments contained wildtype cTn. No effect was observed in the presence of cTn containing R170G/W. cMyBPC-C0C2 significantly reduced binding of wildtype troponin to actin/tropomyosin, but not of both mutant cTn. Moreover, we found a direct troponin/cMyBPC-C0C2 interaction using microscale thermophoresis and identified cTnI and cTnT, but not cTnC as binding partners for cMyBPC-C0C2. Only cTn containing cTnI-R170G showed a reduced affinity towards cMyBPC-C0C2. Our results suggest that the RCM cTnI variants R170G/W impair the communication between thin and thick filament proteins and destabilize thin filaments.
Identifiants
pubmed: 32182250
doi: 10.1371/journal.pone.0229227
pii: PONE-D-19-31904
pmc: PMC7077804
doi:
Substances chimiques
Actins
0
Carrier Proteins
0
TNNI3 protein, human
0
Tropomyosin
0
Troponin I
0
myosin-binding protein C
0
Calcium
SY7Q814VUP
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
e0229227Déclaration de conflit d'intérêts
The authors have declared that no competing interests exist.
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