Recently, Liu et al. studied how excessive alcohol consumption regulates downstream signaling cascades of mammalian target of rapamycin complex 1 (mTORC1), focusing on the Akt/glycogen synthase kinase-3ß (GSK-3ß)/collapsing response mediator protein-2 (CRMP-2) pathway in rodent nucleus accumbens. Excessive alcohol increases protein levels of the microtubule (MT) binding protein CRMP-2 via mTORC1-mediated translation. Additionally, Akt is activated, initiating a sequential cascade of GSK-3ß deactivation by Akt-mediated phosphorylation and a subsequent decrease in GSK-3ß -mediated phosphorylation of CRMP-2. Phosphorylation of CRMP-2 inhibits its binding to MTs and the alcohol-induced reduction in CRMP-2 phosphorylation increases binding between CRMP-2 and MTs, as well as MT asssembly. The authors posit that these alcohol-induced changes in MT binding and protein levels underlie the neuroadaptations (i.e., structural plasticity) that occur in the development and/or maintenance of alcohol-drinking behaviors. Cytoskeleton’s Microtubule Binding Protein Spin-down Assay Kit (Cat. # BK029) and Microtubule/Tubulin In Vivo Assay Kit (Cat. # BK038) were essential reagents in this study, providing quantitation of both MT binding to CRMP-2 and changes in MT content after excessive alcohol consumption. These data suggest that CRMP-2 and its functional relationship with MTs is an essential step in the alcohol-induced neuroadaptations that underlie addiction and addictive behaviors.
HeLa CCL-2 cells were grown to 70% confluency at 37°C/5% CO2. Cells were untreated (lanes S1, P1, S2, P2) or treated with 3.3 mM of the tubulin polymerizing drug paclitaxel (i.e., taxol) for 60 min at 37°C/5% CO2 (lanes S3, P3, S4, P4). Cells were lysed and separated into supernatant (S) and pellet (P) fractions and analyzed by western blot quantitation of tubulin protein according to the Microtubules/Tubulin In Vivo Assay Kit (Cat. # BK038) instructions.
Liu F. et al. 2016. mTORC1-dependent translation of collapsing response mediator protein-2 drives neuroadaptations underlying excessive alcohol-drinking behaviors. Mol. Psychiatry. Doi: 10.1038/mp.2016.12.