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Abstract

1. One type of transglutaminase is usually accumulated in various forms of naturally occurring cell death and apoptosis. The accumulated enzyme is activated during the death process, leading to the formation of cross-linked protein structures. Degradation of the cross-linked apoptotic bodies results in the elevation of the epsilon (gamma-glutamyl)lysine isodipeptide concentration in body fluids, which may provide a diagnostic tool to monitor the apoptosis rate in various tissues under normal and pathologic conditions. 2. Extensive protein cross-linking may be directly related to the act of killing in some cells. In others, the effect of protein cross-linking is palliative, preventing leakage of macromolecules and enhancing phagocytosis of the dead cells. 3. Tissue transglutaminase has been implicated in some physiologic functions of the nervous system. 4. The molecular machinery of apoptosis is present and easily evoked in neuronal cells. 5. Effector elements of the apoptosis process have been associated with the pathogenesis of neurologic disorders. Tissue transglutaminase, representing one of the effector elements of apoptosis, may be induced and activated in cells following ischemia. It may also participate in the formation of abnormal cell inclusions and A beta deposits in amyloid plaques.

Arterial Vimentin Is a Transglutaminase Substrate: A Link between Vasomotor Activity and Remodeling?

“…It is possible that vimentin becomes a transglutaminase substrate when it is released during cellular apoptosis, an event that occurs with a relatively high frequency within the plaque [21, 22]. It is notable in this regard that tissue transglutaminase activity is increased during apoptosis [23, 24]. Evidence for the cellular release of vimentin within the vessel wall has been demonstrated in patients with accelerated transplant vasculopathy.…”

Tissue transglutaminase-induced aggregation of α-synuclein: Implications for Lewy body formation in Parkinson's disease and dementia with Lewy bodies

“…Fourth, increased expression of tTGase itself can be another factor contributing to protein aggregation and subsequent pathogenetic events. The elevated expression of TGase in neurodegenerative disorders including AD, Huntington's disease, and PD (27, 28, 57) may accelerate not only protein aggregation but neuronal apoptosis as well (38,59). Although there is no evidence to date for the involvement of tTGase in apoptotic events occurring in PD, exploring such a link would be of interest.…”

Elevated ε-(γ-Glutamyl)lysine in Human Diabetic Nephropathy Results from Increased Expression and Cellular Release of Tissue Transglutaminase

“…Intracellular tTg has been associated with cell death both as part of the apoptotic program in the formation of the apoptotic envelope [34] and in a novel cell death process independent of apoptosis [35]. In this tTg-mediated cell death process, intracellular tTg appears to become activated in response to intracellular rises in calcium.…”