Table 2.
Characteristics Ascribed to Alarmins (HMGB1) and Comparison with Reported Properties of Prothymosin Alpha
| Characteristic | HMGB1 (Chan et al., 2012, Schiller et al., 2013, Telusma et al., 2006) | ProTα (Cannavo et al., 2013, Halder et al., 2013, Ioannou et al., 2012) |
|---|---|---|
| Origin | Nonhistone nuclear protein | Nonhistone nuclear protein |
| Expression | Expressed in all cells | Expressed in all cells |
| Physiological intracellular role | DNA organization, transcriptional regulator | DNA organization, transcriptional regulator, antiapoptotic and oxidative stress regulator |
| Extracellular role | Cytokine/inflammatory mediator | Cytokine/inflammatory mediator |
| Release mechanism | Passive release and active secretion | Release upon ischemic stress |
| Receptors | TLR2, TLR4, TLR9, TIM3, and RAGE | TLR4 |
| Regenerative potential | Cardiac and nervous cell regeneration, skin wound healing, bone repair, skeletal muscle repair | Cardiac and nervous cell regeneration |
| Implication in diseases | Cancer, rheumatoid arthritis stroke, atherosclerosis, sepsis | Cancer, autoimmune diseases, ischemic stroke, viral infections |
| Additional similarities | ||
| Immunoactive peptides | Hp-106, Hp-31, Hp-91, and Hp-16 | ProTα(100–109), proTα(50–89), Tα1 |
| Intracellular mobility | Translocation from nucleus to cytoplasm; during apoptosis, translocation into apoptotic cell-derived membranous vesicles | Translocation from nucleus to cytoplasm; during apoptosis, NLS cleavage by caspases and generation of proTα(100–109) |