A possible role for adenosine monophosphate‐activated protein kinase in regulating tubulin acetylation (739.10)

Abstract

Microtubules (MTs) play important roles in cell motility, mitosis, and intracellular vesicle transport. These functions are regulated by microtubule associated proteins and/or tubulin posttranslational modifications, which can alter the structure and dynamics of the microtubules. Prior research showed that ATP depletion results in microtubules that are stable to the effects of MT‐depolymerizing drugs. The stable microtubules were also shown to be enriched in detyrosinated tubulin, but no information existed on other tubulin posttranslational modifications. We investigated whether microtubules in ATP‐depleted C3H10T1/2 mouse fibroblasts are more heavily acetylated, and if so, whether the acetylation is dependent on the activity of Adenosine Monophosphate‐Activated Protein Kinase (AMPK). We found that depleting cells of ATP by treatment with sodium azide and 2‐deoxyglucose resulted in a substantial increase in acetylated tubulin, as seen by western blot analysis and immunofluorescence microscopy. Most but not all stable microtubules showed tubulin acetylation. Since various energy stressors are known to activate AMPK, we next ascertained by western blotting that ATP‐depletion led to an increase in phosph‐AMPK, the active form of the enzyme. Cells treated with the AMPK inhibitor, Compound C, prior to ATP depletion showed less tubulin acetylation than cells treated with ATP‐depleting drugs alone. These results suggest a link between the level of tubulin acetylation and the metabolic state of the cells.