Decline of contractility during ischemia-reperfusion injury: actin glutathionylation and its effect on allosteric interaction with tropomyosin

Abstract

The severity and duration of ischemia-reperfusion injury is hypothesized to play an important role in the ability of the heart subsequently to recover contractility. Permeabilized trabeculae were prepared from a rat model of ischemia-reperfusion injury to examine the impact on force generation. Compared with the control perfused condition, the maximum force (F(max)) per cross-sectional area and the rate of tension redevelopment of Ca(2+)-activated trabeculae fell by 71% and 44%, respectively, during ischemia despite the availability of a high concentration of ATP. The reduction in F(max) with ischemia was accompanied by a decline in fiber stiffness, implying a drop in the absolute number of attached cross bridges. However, the declines during ischemia were largely recovered after reperfusion, leading to the hypothesis that intrinsic, reversible posttranslational modifications to proteins of the contractile filaments occur during ischemia-reperfusion injury. Examination of thin-filament proteins from ischemic or ischemia-reperfused hearts did not reveal proteolysis of troponin I or T. However, actin was found to be glutathionylated with ischemia. Light-scattering experiments demonstrated that glutathionylated G-actin did not polymerize as efficiently as native G-actin. Although tropomyosin accelerated the time course of native and glutathionylated G-actin polymerization, the polymerization of glutathionylated G-actin still lagged native G-actin at all concentrations of tropomyosin tested. Furthermore, cosedimentation experiments demonstrated that tropomyosin bound glutathionylated F-actin with significantly reduced cooperativity. Therefore, glutathionylated actin may be a novel contributor to the diverse set of posttranslational modifications that define the function of the contractile filaments during ischemia-reperfusion injury.

A change of heart: oxidative stress in governing muscle function?

“…The S-glutathionylation of actin is increased after post-ischemic reperfusion and causes decreased actin-tropomyosin interactions (Canton et al 2004;Chen and Ogut 2006). Furthermore, S-glutathionylation of actin limits polymerization of globular (G)-actin to filament (F)-actin (Wang et al 2001;Dalle-Donne et al 2003a).…”

“…Force generation is produced via the cyclic interaction between actin and myosin filaments. This interaction is controlled by the tropomyosin-troponin complex bound to the actin filament (Canton et al 2006;Chen and Ogut 2006;Horwitz et al 1979). All mechanisms that regulate Ca 2+ in skeletal and cardiac muscles are known to be susceptible to oxidative stress produced by organic free radicals and ROS (Comporti 1989).…”

Redox regulation of human estrogen sulfotransferase (hSULT1E1)

“…Redox modification of Cys residues of an enzyme provides a mechanism for regulating enzyme activity [10]. Proteins can be S-glutathionylated [11] or S-nitrosylated [12], especially during oxidative stress. Oxidative stress is involved in the pathogenesis of various degenerative diseases, including cancer [13].…”

Regulation of protein function by S-nitrosation and S-glutathionylation: processes and targets in cardiovascular pathophysiology

“…Of note, GAPDH activity is restored at the end of reperfusion, thus suggesting that S-glutathionylation may constitute a temporary protection of catalytic cysteines from irreversible oxidation. Additional studies highlighted the S-glutathionylation of actin in a rat model of in vivo IR (Chen and Ogut, 2006). Studies on isolated G-actin indicated that its S-glutathionylation can delay its rate of polymerization and decrease the cooperativity of its binding to tropomyosin, suggesting that the phenomenon may contribute to the decline in cardiac contractility observed during ischemia (Wang et al, 2001a,b).…”