TY - JOUR
T1 - Single molecule kinetics in the familial hypertrophic cardiomyopathy D166V mutant mouse heart
AU - Muthu, Priya
AU - Mettikolla, Prasad
AU - Calander, Nils
AU - Luchowski, Rafal
AU - Gryczynski, Ignacy
AU - Gryczynski, Zygmunt
AU - Szczesna-Cordary, Danuta
AU - Borejdo, J.
N1 - Funding Information:
The authors thank Jingsheng Liang (Univ. of Miami, Miller School of Medicine) for the preparation of glycerinated skinned ventricular muscle fibers from Tg-WT and Tg-D166V mice. This work was supported by the NIH grants: R01AR048622 (to J.B.), R01HL071778 (to D.S-C.), R01HL090786 (to J.B. and D.S-C.) and by Texas ETF grant (CCFT). R.L. is the recipient of the Research Mobility program from the Polish Ministry of Science and Higher Education.
PY - 2010/5
Y1 - 2010/5
N2 - One of the sarcomeric mutations associated with a malignant phenotype of familial hypertrophic cardiomyopathy (FHC) is the D166V point mutation in the ventricular myosin regulatory light chain (RLC) encoded by the MYL2 gene. In this report we show that the rates of myosin cross-bridge attachment and dissociation are significantly different in isometrically contracting cardiac myofibrils from right ventricles of transgenic (Tg)-D166V and Tg-WT mice. We have derived the myosin cross-bridge kinetic rates by tracking the orientation of a fluorescently labeled single actin molecule. Orientation (measured by polarized fluorescence) oscillated between two states, corresponding to the actin-bound and actin-free states of the myosin cross-bridge. The rate of cross-bridge attachment during isometric contraction decreased from 3 s-1 in myofibrils from Tg-WT to 1.4 s-1 in myofibrils from Tg-D166V. The rate of detachment decreased from 1.3 s-1 (Tg-WT) to 1.2 s-1 (Tg-D166V). We also showed that the level of RLC phosphorylation was largely decreased in Tg-D166V myofibrils compared to Tg-WT. Our findings suggest that alterations in the myosin cross-bridge kinetics brought about by the D166V mutation in RLC might be responsible for the compromised function of the mutated hearts and lead to their inability to efficiently pump blood.
AB - One of the sarcomeric mutations associated with a malignant phenotype of familial hypertrophic cardiomyopathy (FHC) is the D166V point mutation in the ventricular myosin regulatory light chain (RLC) encoded by the MYL2 gene. In this report we show that the rates of myosin cross-bridge attachment and dissociation are significantly different in isometrically contracting cardiac myofibrils from right ventricles of transgenic (Tg)-D166V and Tg-WT mice. We have derived the myosin cross-bridge kinetic rates by tracking the orientation of a fluorescently labeled single actin molecule. Orientation (measured by polarized fluorescence) oscillated between two states, corresponding to the actin-bound and actin-free states of the myosin cross-bridge. The rate of cross-bridge attachment during isometric contraction decreased from 3 s-1 in myofibrils from Tg-WT to 1.4 s-1 in myofibrils from Tg-D166V. The rate of detachment decreased from 1.3 s-1 (Tg-WT) to 1.2 s-1 (Tg-D166V). We also showed that the level of RLC phosphorylation was largely decreased in Tg-D166V myofibrils compared to Tg-WT. Our findings suggest that alterations in the myosin cross-bridge kinetics brought about by the D166V mutation in RLC might be responsible for the compromised function of the mutated hearts and lead to their inability to efficiently pump blood.
KW - Familial hypertrophic cardiomyopathy
KW - Fluorescence correlation spectroscopy
KW - Fluorescence lifetime
KW - Regulatory light chain of myosin
KW - Sarcomere
KW - Single molecule detection
UR - http://www.scopus.com/inward/record.url?scp=77951622927&partnerID=8YFLogxK
U2 - 10.1016/j.yjmcc.2009.11.004
DO - 10.1016/j.yjmcc.2009.11.004
M3 - Article
C2 - 19914255
AN - SCOPUS:77951622927
SN - 0022-2828
VL - 48
SP - 989
EP - 998
JO - Journal of Molecular and Cellular Cardiology
JF - Journal of Molecular and Cellular Cardiology
IS - 5
ER -