Engineered Troponin C Constructs Correct Disease-related Cardiac Myofilament Calcium Sensitivity

Liu, Bin; Lee, Ryan S.; Biesiadecki, Brandon J.; Tikunova, Svetlana B.; Davis, Jonathan P.

doi:10.1074/jbc.m111.334953

Cited by 25 publications

(37 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly, TnI phosphorylation had a negligible effect on the myosin S1 disassociation component of thin filament deactivation with all 3 phosphorylation combinations minimally slowing S1 disassociation by about 25% of wild-type. Consistent with these phosphorylation data, we have also reported similar differential effects of TnI and TnT disease mutations on Ca 2+ sensitivity and dissociation rates [22, 32]. The combination effect of TnI Ser-150 and Ser-23/24 phosphorylation on dissociation was not the result of a pH effect but rather resulted from combination of the phosphate residues as demonstrated by the identical dissociation rates of TnI S23/24/150D at both pH 6.5 and 7.0 (Fig.…”

Section: Discussionsupporting

confidence: 83%

“…Following reconstitution, 0.2 mM Ca 2+ was added to saturate Tn or the thin filament. Ca 2+ saturated thin filament or Tn was rapidly mixed with EGTA buffer and Ca 2+ dissociation was monitored by the change in IAANS fluorescence at 15°C as previously described [22, 23]. …”

Section: Methodsmentioning

confidence: 99%

“…Following reconstitution EGTA was added to 5 mM and myosin S1 added at a ratio of 7:4 (actin:myosin S1). Rigor bound myosin S1 thin filaments were then rapidly mixed with ATP (2 mM final) and the dissociation of myosin monitored by the change in IAANS fluorescence at 15°C as previously described [22, 23]. …”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2+ sensitivity and accelerates deactivation in an acidic environment

Nixon¹,

Walton²,

Zhang³

et al. 2014

Journal of Molecular and Cellular Cardiology

Self Cite

View full text Add to dashboard Cite

The binding of Ca2+ to troponin C (TnC) in the troponin complex is a critical step regulating the thin filament, the actin-myosin interaction and cardiac contraction. Phosphorylation of the troponin complex is a key regulatory mechanism to match cardiac contraction to demand. Here we demonstrate phosphorylation of the troponin I (TnI) subunit is simultaneously increased at Ser-150 and Ser-23/24 during in vivo myocardial ischemia. Myocardial ischemia decreases intracellular pH resulting in depressed binding of Ca2+ to TnC and impaired contraction. To determine the pathological relevance of simultaneous TnI phosphorylation we measured individual TnI Ser-150 (S150D), Ser-23/24 (S23/24D) and combined (S23/24/150D) pseudo-phosphorylation effects on thin filament regulation at acidic pH similar to that in myocardial ischemia. Results demonstrate that while acidic pH decreased thin filament Ca2+ binding to TnC regardless of TnI composition, TnI S150D attenuated this decrease rendering it similar to non-phosphorylated TnI at normal pH. The dissociation of Ca2+ from TnC was unaltered by pH such that TnI S150D remained slow, S23/24D remained accelerated and the combined S23/24/150D remained accelerated. This effect of the combined TnI Ser-150 and Ser-23/24 pseudo-phosphorylation to maintain Ca2+ binding while accelerating Ca2+ dissociation represents the first post-translational modification of troponin by phosphorylation to both accelerate thin filament deactivation and maintain Ca2+ sensitive activation. These data suggest TnI Ser-150 phosphorylation attenuation of the pH-dependent decrease in Ca2+ sensitivity and its combination with Ser-23/24 phosphorylation to maintain accelerated thin filament deactivation may impart an adaptive role to preserve contraction during acidic ischemia pH without slowing relaxation.

show abstract

Section: Discussionsupporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2+ sensitivity and accelerates deactivation in an acidic environment

Nixon¹,

Walton²,

Zhang³

et al. 2014

Journal of Molecular and Cellular Cardiology

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is important to note that we used skeletal actin and myosin S1 in this study because of our extensive prior work using these proteins (15; 30; 35; 40; 50). However, skeletal and cardiac actins are 99 % identical, differing by only four amino acids.…”

Section: Discussionmentioning

confidence: 99%

Molecular and functional consequences of mutations in the central helix of cardiac troponin C

Swindle

Albury

Baroud

et al. 2014

Archives of Biochemistry and Biophysics

Self Cite

View full text Add to dashboard Cite

The objective of this work was to investigate the role of acidic residues within the exposed middle segment of the central helix of cTnC in (1) cTnC-cTnI interactions, (2) Ca2+ binding and exchange with the regulatory N-domain of cTnC in increasingly complex biochemical systems, and (3) ability of the cTn complex to regulate actomyosin ATPase. In order to achieve this objective, we introduced the D87A/D88A and E94A/E95A/E96A mutations into the central helix of cTnC. The D87A/D88A and E94A/E95A/E96A mutations decreased affinity of cTnC for the regulatory region of cTnI. The Ca2+ sensitivity of the regulatory N-domain of isolated cTnC was decreased by the D87A/D88A, but not E94A/E95A/E96A mutation. However, both the D87A/D88A and E94A/E95A/E96A mutations desensitized the cTn complex and reconstituted thin filaments to Ca2+. Decreases in the Ca2+ sensitivity of the cTn complex and reconstituted thin filaments were, at least in part, due to faster rates of Ca2+ dissociation. In addition, the D87A/D88A and E94A/E95A/E96A mutations desensitized actomyosin ATPase to Ca2+, and decreased maximal actomyosin ATPase activity. Thus, our results indicate that conserved acidic residues within the exposed middle segment of the central helix of cTnC are important for the proper regulatory function of the cTn complex.

show abstract

“…68,71,78 A mutation in troponin C resulting in calcium-independent sarcomeric perturbation has been shown to be rescued by an engineered molecule. 79 …”

Section: The Sarcomerementioning

confidence: 99%

From Stem Cells to Cardiomyocytes

Kaushik¹,

Engler²

2014

Progress in Molecular Biology and Translational Science

View full text Add to dashboard Cite

Stem cell differentiation into a variety of lineages is known to involve signaling from the extracellular niche, including from the physical properties of that environment. What regulates stem cell responses to these cues is there ability to activate different mechanotransductive pathways. Here, we will review the structures and pathways that regulate stem cell commitment to a cardiomyocyte lineage, specifically examining proteins within muscle sarcomeres, costameres, and intercalated discs. Proteins within these structures stretch, inducing a change in their phosphorylated state or in their localization to initiate different signals. We will also put these changes in the context of stem cell differentiation into cardiomyocytes, their subsequent formation of the chambered heart, and explore negative signaling that occurs during disease.

show abstract

Engineered Troponin C Constructs Correct Disease-related Cardiac Myofilament Calcium Sensitivity

Cited by 25 publications

References 56 publications

Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2+ sensitivity and accelerates deactivation in an acidic environment

Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2+ sensitivity and accelerates deactivation in an acidic environment

Molecular and functional consequences of mutations in the central helix of cardiac troponin C

From Stem Cells to Cardiomyocytes

Contact Info

Product

Resources

About