Decreased S -Nitrosylation of Tissue Transglutaminase Contributes to Age-Related Increases in Vascular Stiffness

Abstract

Rationale: Although an age-related decrease in NO bioavailability contributes to vascular stiffness, the underlying molecular mechanisms remain incompletely understood. We hypothesize that NO constrains the activity of the matrix crosslinking enzyme tissue transglutaminase (TG2) via S-nitrosylation in young vessels, a process that is reversed in aging. Objective: We sought to determine whether endothelium-dependent NO regulates TG2 activity by S-nitrosylation and whether this contributes to age-related vascular stiffness. Methods and Results: We first demonstrate that NO suppresses activity and increases S-nitrosylation of TG2 in cellular models. Next, we show that nitric oxide synthase (NOS) inhibition leads to increased surface and extracellular matrix-associated TG2. We then demonstrate that endothelium-derived bioactive NO primarily mediates its effects through TG2, using TG2 ؊/؊ mice chronically treated with the NOS inhibitor L-N Gnitroarginine methyl ester (L-NAME). We confirm that TG2 activity is modulated by endothelium-derived bioactive NO in young rat aorta. In aging rat aorta, although TG2 expression remains unaltered, its activity increases and S-nitrosylation decreases. Furthermore, TG2 inhibition decreases vascular stiffness in aging rats. Finally, TG2 activity and matrix crosslinks are augmented with age in human aorta, whereas abundance remains unchanged. Conclusions: Decreased S-nitrosylation of TG2 and increased TG activity lead to enhanced matrix crosslinking and contribute to vascular stiffening in aging. TG2 appears to be the member of the transglutaminase family primarily contributing to this phenotype. Inhibition of TG2 could thus represent a therapeutic target for age-associated vascular stiffness and isolated systolic hypertension. (Circ Res. 2010;107:117-125.)Key Words: tissue transglutaminase Ⅲ S-nitrosylation Ⅲ S-nitrosation Ⅲ aging Ⅲ vascular stiffness A ging is associated with alterations in the properties of all elements of the vascular wall including endothelium, vascular smooth muscle, and matrix. 1 These changes result in increased vascular stiffness and isolated systolic hypertension. In addition, increased vascular stiffness promotes atherosclerosis at various sites in the vascular tree, such as the carotid artery. 2,3 Both dynamic changes (alterations in endothelial function and effects on vascular smooth muscle contractility), as well as structural alterations (eg, fracturing of elastin, increased collagen content, and accumulation of advanced glycation end products) have been described in aging. Vessel structure can additionally be regulated by alterations in matrix crosslinking. 1 Transglutaminases (TGs) are enzymes that catalyze a transamidation reaction, leading to the crosslinking of proteins through the formation of the stable N--(␥-glutamyl)lysine isopeptide bonds. 4,5 At least 3 of the 9 members of the TG superfamily are expressed in vascular systems. Tissue transglutaminase (TG2) in particular is ubiquitously expressed in vasculature, including in endothelial ce...

Age-dependent Effects of 17β-estradiol on the Dynamics of Estrogen Receptor β (ERβ) Protein–Protein Interactions in the Ventral Hippocampus

“…Interestingly, the ER␤-selective agonist diarylproprionitrile induces S-nitrosylation proteins as a cardioprotective mechanism in the heart (49). Loss of S-nitrosylated proteins with age could ostensibly contribute to a loss of cardioprotective effects of E2 in older patients (50). Moreover, S-nitrosylation of interaction partners mediated through ER␤ could result in the characteristic "chain" patterns observed in the 2D-DIGE experiments.…”

Vascular ageing and endothelial cell senescence: Molecular mechanisms of physiology and diseases

“…At cellular level, it has been shown that decreased nitric oxide (NO) bioavailability plays and important role in age-related vascular stiffness. Indeed, TG2 extracellular secretion and crosslinking activity are inhibited by S-nitrosylation, a post-translational modification of the cysteine residues in TG2 active site, by NO (Santhanam et al, 2010;Melino et al, 1997). Decreases in NO in arteria of old rats results to decreased TG2 S-nitrosylation, increased TG2 in the vascular matrix, and increased TG2 crosslinking function (Santhanam et al, 2010;Steppan et al, 2014).…”

S-Nitrosylation: Specificity, Occupancy, and Interaction with Other Post-Translational Modifications

“…The diversity of regulatory mechanisms for SNO might account for the ability of SNO to regulate a variety of cellular conditions. Indeed, studies have implicated regulation by SNO in sex-specific protein changes (13,81,110), aging (95,97), cardiovascular disease (5,36,58,59,85,107,109), and renal function (113), to name a few.…”