Functional Analysis of a Troponin I (R145G) Mutation Associated with Familial Hypertrophic Cardiomyopathy
| Autor: | Aldrin V. Gomes, Todd Miller, Philippe R. Housmans, Rosalyn Lang, Jiaju Zhao, James D. Potter |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
medicine.medical_specialty
Time Factors Arginine Swine Molecular Sequence Data Muscle Fibers Skeletal Mutation Missense macromolecular substances Myosins Biochemistry Muscle hypertrophy Troponin C Internal medicine Troponin I Cardiomyopathy Hypertrophic Familial medicine Animals Humans Missense mutation Amino Acid Sequence Molecular Biology Adenosine Triphosphatases Binding Sites Dose-Response Relationship Drug biology Chemistry Circular Dichroism Myocardium Temperature Cardiac muscle Wild type Cell Biology Models Theoretical Troponin medicine.anatomical_structure Endocrinology Mutation biology.protein Calcium Stress Mechanical Muscle Contraction |
| Zdroj: | Journal of Biological Chemistry. 277:11670-11678 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m108912200 |
| Popis: | Familial hypertrophic cardiomyopathy has been associated with several mutations in the gene encoding human cardiac troponin I (HCTnI). A missense mutation in the inhibitory region of TnI replaces an arginine residue at position 145 with a glycine and cosegregates with the disease. Results from several assays indicate that the inhibitory function of HCTnI(R145G) is significantly reduced. When HCTnI(R145G) was incorporated into whole troponin, Tn(R145G) (HCTnT small middle dotHCTnI(R145G) small middle dotHCTnC), only partial inhibition of the actin-tropomyosin-myosin ATPase activity was observed in the absence of Ca(2+) compared with wild type Tn (HCTnT small middle dotHCTnI small middle dotHCTnC). Maximal activation of actin-tropomyosin-myosin ATPase in the presence of Ca(2+) was also decreased in Tn(R145G) when compared with Tn. Using skinned cardiac muscle fibers, we determined that in comparison with the wild type complex 1) the complex containing HCTnI(R145G) only inhibited 84% of Ca(2+)-unregulated force, 2) the recovery of Ca(2+)-activated force was decreased, and 3) there was a significant increase in the Ca(2+) sensitivity of force development. Computer modeling of troponin C and I variables predicts that the primary defect in TnI caused by these mutations would lead to diastolic dysfunction. These results suggest that severe diastolic dysfunction and somewhat decreased contractility would be prominent clinical features and that hypertrophy could arise as a compensatory mechanism. |
| Databáze: | OpenAIRE |
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