The Apoptotic Microtubule Network During the Execution Phase of Apoptosis

Apoptosis is a regulated energy-dependent process of cell death characterized by specific morphological and biochemical features in which caspase activation has a central role. During apoptosis, cells undergo characteristic morphological rear‐ rangements in which the cytoskeleton participates actively. From a historical point of view, this reorganization has been assigned mainly to actinomyosin ring contraction with microtubule and intermediate filaments, both reported to be de‐ polymerized at early stages of apoptosis. However, recent results have shown that the microtubule cytoskeleton is reformed during the execution phase of apoptosis, forming an apoptotic microtubule network (AMN). AMN is closely as‐ sociated with the plasma membrane, forming a cortical ring or cellular “cocoon.” Apoptotic microtubules’ reorganization has been reported in many cell types and under many apoptotic inducers. Recently, it has been proposed that AMN is es‐ sential for preserving plasma membrane permeability and cell morphology dur‐ ing the execution phase of apoptosis. Apoptotic microtubules’ depolymerization leads cells to secondary necrosis and the release of toxic intracellular contents that can harm surrounding cells and initiate inflammation. Therefore, microtu‐ bules’ reorganization in physiological apoptosis during development and in the adult organism or in pathological apoptosis induced by anticancer treatments or chronic inflammation is essential for tissue homeostasis, preventing cell damage and inflammation.