Abstract
Colchicine has been used to treat gout and, more recently, to effectively prevent autoinflammatory diseases and both primary and recurrent episodes of pericarditis. The anti-inflammatory action of colchicine seems to result from irreversible inhibition of tubulin polymerization and microtubule (MT) assembly by binding to the tubulin heterodimer, avoiding the signal transduction required to the activation of the entire NLRP3 inflammasome. Emerging results show that the MT network is a potential regulator of cardiac mechanics. Here, we investigated how colchicine impacts in tubulin folding cofactors TBCA, TBCB, and TBCE activities. We show that TBCA is abundant in mouse heart insoluble protein extracts. Also, a decrease of the TBCA/β-tubulin complex followed by an increase of free TBCA is observed in human cells treated with colchicine. The presence of free TBCA is not observed in cells treated with other anti-mitotic agents such as nocodazole or cold shock, neither after translation inhibition by cycloheximide. In vitro assays show that colchicine inhibits tubulin heterodimer dissociation by TBCE/TBCB, probably by interfering with interactions of TBCE with tubulin dimers, leading to free TBCA. Manipulation of TBCA levels, either by RNAi or overexpression results in decreased levels of tubulin heterodimers. Together, these data strongly suggest that TBCA is mainly receiving β-tubulin from the dissociation of pre-existing heterodimers instead of newly synthesized tubulins. The TBCE/TBCB+TBCA system is crucial for controlling the critical concentration of free tubulin heterodimers and MT dynamics in the cells by recycling the tubulin heterodimers. It is conceivable that colchicine affects tubulin heterodimer recycling through the TBCE/TBCB+TBCA system producing the known benefits in the treatment of pericardium inflammation.
Highlights
Microtubules (MTs) are dynamic polymers of heterodimers of α- and β-tubulin that grow and shrink by the addition and removal of tubulin heterodimers at their ends
Contrary to TBCB, TBCE, and TBCD, TBCA is not able to dissociate the native tubulin heterodimer by itself (Martín et al, 2000; Kortazar et al, 2006, 2007; Carranza et al, 2013), but after tubulin heterodimer dissociation, TBCA forms a stable complex with β-tubulin, being responsible for its recycling/degradation (Kortazar et al, 2007)
According to Llosa et al (1996) when protein extracts from cells are analyzed in this type of native gels, it is expected that the anti-TBCA sera will be able to detect the free TBCA and a faster migrating band corresponding to the TBCA/β-tubulin complex
Summary
Microtubules (MTs) are dynamic polymers of heterodimers of α- and β-tubulin that grow and shrink by the addition and removal of tubulin heterodimers at their ends. MT arrays are present in almost all eukaryotic cells constituting, together with actin and intermediate filaments, the cytoskeleton. MTs, in crosstalk with other cytoskeleton members, play many roles in cell spatial. Colchicine Inhibits Tubulin Heterodimer Dissociation organization, the establishment of cellular asymmetries and polarity, intracellular transport, cell migration, and morphogenesis (Dogterom and Koenderink, 2019). These polymers are the main constituents of complex structures such as the mitotic and meiotic spindles, centrioles/basal bodies, and the ciliary axoneme, being involved in cell division, motility, and signaling. MTs are modulated by a vast number of MT-binding proteins with multiple activities (for review, Goodson and Jonasson, 2018)
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