What question did this study set out to answer?

This research investigates how specific phosphorylation sites on cardiac troponin I affect cardiac function.

March 1, 2003Journal of Biological ChemistryOpen Access

Phosphorylation or Glutamic Acid Substitution at Protein Kinase C Sites on Cardiac Troponin I Differentially Depress Myofilament Tension and Shortening Velocity

Q: What is the clinical evidence from this study?

Study design: Other. Intervention: Phosphorylation or glutamic acid substitution at Protein Kinase C sites on cardiac troponin I vs. Controls. Primary outcome: Ca(2+)-dependence of force, maximum tension, and sliding speed.

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Key result

Phosphorylation or glutamic acid substitution at PKC sites on cardiac troponin I differentially depressed myofilament maximum tension by up to 27% and altered Ca(2+) sensitivity and sliding speed.

Population

Detergent-skinned mouse cardiac fiber bundles and reconstituted thin filament preparations

Comparison

Replacement of endogenous cTnI with cTnI… vs Controls (unmodified/endogenous cTnI)

Design

Preclinical

Authors

EBEileen M. BurkartWashington University in St. Louis MSMarius P. SumandeaBioMarin (United States)TKTomoyoshi KobayashiIllinois College

Discussion

Member takes

Implication

Site-specific cTnI phosphorylation effects on tension remain preclinical; leaves open targeted myofilament therapies in human disease.

Key Points

This research investigates how specific phosphorylation sites on cardiac troponin I affect cardiac function.
Measured tension and sliding speed of thin filaments in reconstituted preparations with different cTnI modifications.
Used detergent-skinned mouse cardiac fiber bundles to assess Ca(2+)-dependence of force.
Performed in vitro motility assays with actin filaments regulated by various cTnI forms.
Phosphorylated cTnI led to up to 27% lower maximum tension compared to controls.
Actin filaments with cTnI-S43E/S45E/T144E exhibited decreased calcium sensitivity and maximum sliding speed.
cTnI-T144E showed desensitization to calcium but no change in maximum tension.

Structured PICO

Population

Detergent-skinned mouse cardiac fiber bundles and reconstituted thin filament preparations

Intervention

Replacement of endogenous cTnI with cTnI phosphorylated by protein kinase C-epsilon or mutated to cTnI-S43E/S45E/T144E, cTnI-S43E/S45E, or cTnI-T144E

Comparator

Controls (unmodified/endogenous cTnI)

Outcome

Ca(2+)-dependence of force (tension) and maximum sliding speedsurrogate

PKC phosphorylation at specific sites on cardiac troponin I differentially modulates myofilament tension and shortening velocity, highlighting the complexity of actin-myosin regulation.

Cite This Study

Burkart et al. (2003) studied this question. Phosphorylation or glutamic acid substitution at Protein Kinase C sites on cardiac troponin I vs. Controls was evaluated on Ca(2+)-dependence of force, maximum tension, and sliding speed. Phosphorylation or glutamic acid substitution at PKC sites on cardiac troponin I differentially depressed myofilament maximum tension by up to 27% and altered Ca(2+) sensitivity and sliding speed.

synapsesocial.com/papers/6a6a8137050bc01bbbcb2eab https://doi.org/10.1074/jbc.m210712200

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Phosphorylation or Glutamic Acid Substitution at Protein Kinase C Sites on Cardiac Troponin I Differentially Depress Myofilament Tension and Shortening Velocity

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Phosphorylation or Glutamic Acid Substitution at Protein Kinase C Sites on Cardiac Troponin I Differentially Depress Myofilament Tension and Shortening Velocity

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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