What does this research mean for the field?

The ΔLys-210 troponin T mutation, which causes dilated cardiomyopathy, reduces maximum ATPase activation and sliding speed while altering Ca2+ sensitivity, producing functional consequences that are distinct from hypertrophic cardiomyopathy-causing mutations like R92Q. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To compare the in vitro regulatory consequences of the dilated cardiomyopathy mutation ΔLys-210 and the hypertrophic cardiomyopathy mutation R92Q in human cardiac troponin T.

October 1, 2002Journal of Biological ChemistryOpen Access

Alterations in Thin Filament Regulation Induced by a Human Cardiac Troponin T Mutant That Causes Dilated Cardiomyopathy Are Distinct from Those Induced by Troponin T Mutants That Cause Hypertrophic Cardiomyopathy

Q: What is the clinical evidence from this study?

Population: Dilated cardiomyopathy and Hypertrophic cardiomyopathy. Intervention: Recombinant human cardiac troponin with ΔLys-210 or R92Q troponin T mutants vs. Wild type troponin T. Primary outcome: In vitro regulatory properties (ATPase activity and sliding speed).

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Key result

The ΔLys-210 troponin T mutant reduced maximum ATPase activation and sliding speed and increased Ca2+ sensitivity (ΔpCa50 = +0.2), effects distinct from the R92Q hypertrophic cardiomyopathy mutant.

Key Points

To compare the in vitro regulatory consequences of the dilated cardiomyopathy mutation ΔLys-210 and the hypertrophic cardiomyopathy mutation R92Q in human cardiac troponin T.
Reconstituted recombinant human cardiac troponin complexes containing wild-type, ΔLys-210, or R92Q troponin T alongside actin and tropomyosin.
Assayed actin-tropomyosin-activated myosin subfragment-1 ATPase activity and thin filament sliding velocity across calcium concentrations from pCa 8.5 to 4.5.
Troponin containing ΔLys-210 retained wild-type inhibition at pCa 8.5 (>80%) but substantially reduced maximal ATPase activation at pCa 4.5, increased Ca2+ sensitivity (ΔpCa50 = +0.2 pCa units), abolished cooperativity, and reduced filament sliding speed.
Equimolar mixtures of wild-type and ΔLys-210 troponin T decreased Ca2+ sensitivity relative to wild-type while preserving the diminished maximal ATPase activation and sliding velocity.
In contrast, the R92Q troponin T mutant conferred reduced inhibition at pCa 8.5, heightened maximal activation at pCa 4.5, and increased Ca2+ sensitivity with unaltered cooperativity.

Structured PICO

Population

In vitro reconstituted thin filaments using recombinant human cardiac troponin, rabbit skeletal muscle actin, rabbit and human cardiac muscle α-tropomyosin, and subfragment-1 (S-1) from rabbit skeletal muscle myosin

Intervention

Recombinant human cardiac troponin containing the ΔLys-210 troponin T mutant (causes dilated cardiomyopathy)

Comparator

Recombinant human cardiac troponin containing wild type troponin T or the R92Q troponin T mutant (causes hypertrophic cardiomyopathy)

Outcome

Actin-tropomyosin-activated myosin subfragment-1 ATPase activity and sliding speed in in vitro motility assaysurrogate

The ΔLys-210 troponin T mutation causing DCM produces distinct functional alterations (reduced ATPase activation and sliding speed, loss of cooperativity) compared to HCM mutations, suggesting different primary triggers for these cardiomyopathies.

Discussion

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Implication

Distinguishes DCM-linked troponin effects from HCM in vitro; hypothesis-generating for distinct cardiomyopathy triggers pending human validation.

Cite This Study

Robinson et al. (2002) studied Dilated cardiomyopathy and Hypertrophic cardiomyopathy. Recombinant human cardiac troponin with ΔLys-210 or R92Q troponin T mutants vs. Wild type troponin T was evaluated on In vitro regulatory properties (ATPase activity and sliding speed). The ΔLys-210 troponin T mutant reduced maximum ATPase activation and sliding speed and increased Ca2+ sensitivity (ΔpCa50 = +0.2), effects distinct from the R92Q hypertrophic cardiomyopathy mutant.

synapsesocial.com/papers/6a1540bed64fa333899f6e75 https://doi.org/10.1074/jbc.m203446200

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Implication

Distinguishes DCM-linked troponin effects from HCM in vitro; hypothesis-generating for distinct cardiomyopathy triggers pending human validation.

Alterations in Thin Filament Regulation Induced by a Human Cardiac Troponin T Mutant That Causes Dilated Cardiomyopathy Are Distinct from Those Induced by Troponin T Mutants That Cause Hypertrophic Cardiomyopathy

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Alterations in Thin Filament Regulation Induced by a Human Cardiac Troponin T Mutant That Causes Dilated Cardiomyopathy Are Distinct from Those Induced by Troponin T Mutants That Cause Hypertrophic Cardiomyopathy

Key Points

Structured PICO

Discussion

Implication

Cite This Study

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