Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients

Danuta Szczesna-Cordary, Michelle Jones, Jeffrey R. Moore, James Watt, W. Glenn Kerrick, Yuanyuan Xu, Ying Wang, Cory Wagg, Gary D. Lopaschuk

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The glutamic acid to lysine mutation at the 22nd amino acid residue (E22K) in the human cardiac myosin regulatory light chain (RLC) gene causes familial hypertrophic cardiomyopathy (FHC) with a phenotype of midventricular obstruction and septal hypertrophy. Our recent histopathology results have shown that the hearts of transgenic E22K mice (Tg-E22K) resemble those of human patients, demonstrating enlarged interventricular septa and papillary muscles. In this study, we show no effect of the E22K mutation on the kinetics of mutated myosin in its ATP-powered interaction with fluorescently labeled single actin filaments compared to nontransgenic or transgenic wild-type (Tg-WT) control mice. Likewise, no change in cross-bridge dissociation rates (gapp) was observed in freshly skinned papillary muscle fibers. In contrast, maximal force and ATPase were decreased ∼20% in Tg-E22K skinned papillary muscle fibers and intracellular [Ca2+] and force transients were significantly decreased in intact papillary muscle fibers from Tg-E22K compared to Tg-WT mice. Moreover, energy metabolism measured in isolated working Tg-E22K mouse hearts perfused under conditions of physiologically relevant levels of metabolic demand was similar in Tg-E22K and control hearts before and after 20 min of no-flow ischemia. Our results suggest that the pathological response observed in the E22K myocardium might be triggered by mutation induced changes in the properties of the RLC Ca2+-Mg2+ site, the state of the Ca2+/Mg2+ occupancy and consequently the Ca2+ buffering ability of the RLC. By decreasing the affinity of the RLC for Ca2+, the E22K mutation most likely promotes a Mg 2+-saturated RLC producing less force and ATPase than the Ca 2+-saturated RLC of WT fibers. Decreased Ca2+ binding may also lead to faster Ca2+ dissociation kinetics in Tg-E22K intact fibers resulting in decreased duration and amplitude of [Ca2+] and force transients. These changes when placed in vivo would result in higher workloads and consequently cardiac hypertrophy.

Original languageEnglish
Pages (from-to)3974-3985
Number of pages12
JournalFASEB Journal
Volume21
Issue number14
DOIs
StatePublished - Dec 1 2007

Fingerprint

myosin light chains
Myosin Light Chains
Transgenic Mice
Muscle
Calcium
Papillary Muscles
mutation
calcium
genetically modified organisms
Mutation
Fibers
mice
Light
Adenosine Triphosphatases
muscle fibers
Cardiac Myosins
heart
Kinetics
hypertrophy
Familial Hypertrophic Cardiomyopathy

Keywords

  • Ca/Mg binding to RLC
  • Cardiac hypertrophy
  • Energy metabolism
  • In vitro motility assays
  • Intact and skinned muscle fibers
  • Transgenic mice

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients. / Szczesna-Cordary, Danuta; Jones, Michelle; Moore, Jeffrey R.; Watt, James; Kerrick, W. Glenn; Xu, Yuanyuan; Wang, Ying; Wagg, Cory; Lopaschuk, Gary D.

In: FASEB Journal, Vol. 21, No. 14, 01.12.2007, p. 3974-3985.

Research output: Contribution to journalArticle

Szczesna-Cordary, Danuta ; Jones, Michelle ; Moore, Jeffrey R. ; Watt, James ; Kerrick, W. Glenn ; Xu, Yuanyuan ; Wang, Ying ; Wagg, Cory ; Lopaschuk, Gary D. / Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients. In: FASEB Journal. 2007 ; Vol. 21, No. 14. pp. 3974-3985.
@article{3c7466d895c94a3a861bafd2c8999054,
title = "Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients",
abstract = "The glutamic acid to lysine mutation at the 22nd amino acid residue (E22K) in the human cardiac myosin regulatory light chain (RLC) gene causes familial hypertrophic cardiomyopathy (FHC) with a phenotype of midventricular obstruction and septal hypertrophy. Our recent histopathology results have shown that the hearts of transgenic E22K mice (Tg-E22K) resemble those of human patients, demonstrating enlarged interventricular septa and papillary muscles. In this study, we show no effect of the E22K mutation on the kinetics of mutated myosin in its ATP-powered interaction with fluorescently labeled single actin filaments compared to nontransgenic or transgenic wild-type (Tg-WT) control mice. Likewise, no change in cross-bridge dissociation rates (gapp) was observed in freshly skinned papillary muscle fibers. In contrast, maximal force and ATPase were decreased ∼20{\%} in Tg-E22K skinned papillary muscle fibers and intracellular [Ca2+] and force transients were significantly decreased in intact papillary muscle fibers from Tg-E22K compared to Tg-WT mice. Moreover, energy metabolism measured in isolated working Tg-E22K mouse hearts perfused under conditions of physiologically relevant levels of metabolic demand was similar in Tg-E22K and control hearts before and after 20 min of no-flow ischemia. Our results suggest that the pathological response observed in the E22K myocardium might be triggered by mutation induced changes in the properties of the RLC Ca2+-Mg2+ site, the state of the Ca2+/Mg2+ occupancy and consequently the Ca2+ buffering ability of the RLC. By decreasing the affinity of the RLC for Ca2+, the E22K mutation most likely promotes a Mg 2+-saturated RLC producing less force and ATPase than the Ca 2+-saturated RLC of WT fibers. Decreased Ca2+ binding may also lead to faster Ca2+ dissociation kinetics in Tg-E22K intact fibers resulting in decreased duration and amplitude of [Ca2+] and force transients. These changes when placed in vivo would result in higher workloads and consequently cardiac hypertrophy.",
keywords = "Ca/Mg binding to RLC, Cardiac hypertrophy, Energy metabolism, In vitro motility assays, Intact and skinned muscle fibers, Transgenic mice",
author = "Danuta Szczesna-Cordary and Michelle Jones and Moore, {Jeffrey R.} and James Watt and Kerrick, {W. Glenn} and Yuanyuan Xu and Ying Wang and Cory Wagg and Lopaschuk, {Gary D.}",
year = "2007",
month = "12",
day = "1",
doi = "10.1096/fj.07-8630com",
language = "English",
volume = "21",
pages = "3974--3985",
journal = "FASEB Journal",
issn = "0892-6638",
publisher = "FASEB",
number = "14",

}

TY - JOUR

T1 - Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients

AU - Szczesna-Cordary, Danuta

AU - Jones, Michelle

AU - Moore, Jeffrey R.

AU - Watt, James

AU - Kerrick, W. Glenn

AU - Xu, Yuanyuan

AU - Wang, Ying

AU - Wagg, Cory

AU - Lopaschuk, Gary D.

PY - 2007/12/1

Y1 - 2007/12/1

N2 - The glutamic acid to lysine mutation at the 22nd amino acid residue (E22K) in the human cardiac myosin regulatory light chain (RLC) gene causes familial hypertrophic cardiomyopathy (FHC) with a phenotype of midventricular obstruction and septal hypertrophy. Our recent histopathology results have shown that the hearts of transgenic E22K mice (Tg-E22K) resemble those of human patients, demonstrating enlarged interventricular septa and papillary muscles. In this study, we show no effect of the E22K mutation on the kinetics of mutated myosin in its ATP-powered interaction with fluorescently labeled single actin filaments compared to nontransgenic or transgenic wild-type (Tg-WT) control mice. Likewise, no change in cross-bridge dissociation rates (gapp) was observed in freshly skinned papillary muscle fibers. In contrast, maximal force and ATPase were decreased ∼20% in Tg-E22K skinned papillary muscle fibers and intracellular [Ca2+] and force transients were significantly decreased in intact papillary muscle fibers from Tg-E22K compared to Tg-WT mice. Moreover, energy metabolism measured in isolated working Tg-E22K mouse hearts perfused under conditions of physiologically relevant levels of metabolic demand was similar in Tg-E22K and control hearts before and after 20 min of no-flow ischemia. Our results suggest that the pathological response observed in the E22K myocardium might be triggered by mutation induced changes in the properties of the RLC Ca2+-Mg2+ site, the state of the Ca2+/Mg2+ occupancy and consequently the Ca2+ buffering ability of the RLC. By decreasing the affinity of the RLC for Ca2+, the E22K mutation most likely promotes a Mg 2+-saturated RLC producing less force and ATPase than the Ca 2+-saturated RLC of WT fibers. Decreased Ca2+ binding may also lead to faster Ca2+ dissociation kinetics in Tg-E22K intact fibers resulting in decreased duration and amplitude of [Ca2+] and force transients. These changes when placed in vivo would result in higher workloads and consequently cardiac hypertrophy.

AB - The glutamic acid to lysine mutation at the 22nd amino acid residue (E22K) in the human cardiac myosin regulatory light chain (RLC) gene causes familial hypertrophic cardiomyopathy (FHC) with a phenotype of midventricular obstruction and septal hypertrophy. Our recent histopathology results have shown that the hearts of transgenic E22K mice (Tg-E22K) resemble those of human patients, demonstrating enlarged interventricular septa and papillary muscles. In this study, we show no effect of the E22K mutation on the kinetics of mutated myosin in its ATP-powered interaction with fluorescently labeled single actin filaments compared to nontransgenic or transgenic wild-type (Tg-WT) control mice. Likewise, no change in cross-bridge dissociation rates (gapp) was observed in freshly skinned papillary muscle fibers. In contrast, maximal force and ATPase were decreased ∼20% in Tg-E22K skinned papillary muscle fibers and intracellular [Ca2+] and force transients were significantly decreased in intact papillary muscle fibers from Tg-E22K compared to Tg-WT mice. Moreover, energy metabolism measured in isolated working Tg-E22K mouse hearts perfused under conditions of physiologically relevant levels of metabolic demand was similar in Tg-E22K and control hearts before and after 20 min of no-flow ischemia. Our results suggest that the pathological response observed in the E22K myocardium might be triggered by mutation induced changes in the properties of the RLC Ca2+-Mg2+ site, the state of the Ca2+/Mg2+ occupancy and consequently the Ca2+ buffering ability of the RLC. By decreasing the affinity of the RLC for Ca2+, the E22K mutation most likely promotes a Mg 2+-saturated RLC producing less force and ATPase than the Ca 2+-saturated RLC of WT fibers. Decreased Ca2+ binding may also lead to faster Ca2+ dissociation kinetics in Tg-E22K intact fibers resulting in decreased duration and amplitude of [Ca2+] and force transients. These changes when placed in vivo would result in higher workloads and consequently cardiac hypertrophy.

KW - Ca/Mg binding to RLC

KW - Cardiac hypertrophy

KW - Energy metabolism

KW - In vitro motility assays

KW - Intact and skinned muscle fibers

KW - Transgenic mice

UR - http://www.scopus.com/inward/record.url?scp=36849094890&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=36849094890&partnerID=8YFLogxK

U2 - 10.1096/fj.07-8630com

DO - 10.1096/fj.07-8630com

M3 - Article

C2 - 17606808

AN - SCOPUS:36849094890

VL - 21

SP - 3974

EP - 3985

JO - FASEB Journal

JF - FASEB Journal

SN - 0892-6638

IS - 14

ER -