Fluorescent Probes of Tissue Transglutaminase Reveal Its Association with Arterial Stiffening

Abstract

Tissue transglutaminase (TG2) catalyzes the crosslinking of proteins. TG2 has been implicated in fibrosis and vascular calcification, both of which lead to a common feature of aging known as arterial stiffness. In order to probe the role of TG2 in arterial rigidification, we have prepared a fluorescent irreversible inhibitor as a probe for TG2 activity (RhodB-PGG-K(Acr)-LPF-OH). This probe was synthesized on solid support, characterized kinetically (k(inact) = 0.68 min⁻¹, K(I) = 79 μM), and then used to stain the aorta from rats used as a model of isolated systolic hypertension (ISH). Interestingly, TG2 activity was thus shown to increase over 4 weeks of the hypertension model, corresponding with the previously observed increase in arterial stiffness. These results clearly suggest an association between TG2 and the phenomenon of arterial rigidification.

Post-translational modifications of tubulin: pathways to functional diversity of microtubules

“…Similarly, fluorescent TG-inhibitors [111] will help track TG2 distribution and activity at various stages of neurons, defining roles for TG2 in axonal health and disease. Combining these reagents with the TG2 knockout mouse [112] will further our understanding of tubulin polyamination.…”

Biotechnological Applications of Transglutaminases

“…In addition, of clinical relevance, TG2 is known to play a role in fibrosis and vascular calcification. In order to probe this further, mechanism-based fluorescent inhibitors were designed to covalently label TG2, to investigate how its activity may relate to stiffening of arterial tissues [94]. …”

Vascular Stiffness and Increased Pulse Pressure in the Aging Cardiovascular System

“…NOS uncoupling can have several etiologies including limited substrate (arginine) or cofactor (Tetrahydrobiopterin) availability, as well as a recently identified posttranslational modification by the enzyme glutathionylation (oxidized glutathione) [33–35]. In addition to its vasoactive effects, NO modulates the activity of the matrix crosslinking enzyme transglutaminase (TG) via S-nitrosylation, also leading to increases in arterial stiffening [36, 37]. Other mechanisms recognized as contributing to the development of increased vascular stiffness in aging include a decrease in NOS expression [38], an increase in xanthine oxidase activity [39, 40], and an increase in reactive oxygen species [39, 41], while stiffening itself can lead to a decrease in NOS activity [42].…”