Nocodazole

Nocodazole is an anti-neoplastic agent which exerts its effect in cells by interfering with the polymerization of microtubules. Microtubules are one type of fibre which constitutes the cytoskeleton, and the dynamic microtubule network has several important roles in the cell, including vesicular transport, forming the mitotic spindle and in cytokinesis. Several drugs including vincristine and colcemid are similar to nocodazole in that they interfere with microtubule polymerisation.

As nocodazole affects the cytoskeleton, it is often used in cell biology experiments as a control: for example, some dominant negative Rho small GTPases cause a similar effect as nocodazole, and constitutively activated mutants often reverse or negate the effect.

Nocodazole is frequently used in cell biology laboratories to synchronize the cell division cycle. Cells treated with nocodazole arrest with a G2- or M-phase DNA content when analysed by flow cytometry. Microscopy of nocodazole-treated cells shows that they do enter mitosis but cannot form metaphase spindles because microtubules (of which the spindles are made) cannot polymerise. The absence of microtubule attachment to kinetochores activates the spindle assembly checkpoint, causing the cell to arrest in prometaphase. For cell synchronization experiments, nocodazole is usually used at a concentration of 40-100ng/mL of culture medium for a duration of 12-18 hrs. Prolonged arrest of cells in mitosis due to nocodazole treatment typically results in cell death by apoptosis.

Another standard cell biological application of Nocodazole is to induce the formation of Golgi ministacks in eukaryotic cells. The perinuclear structural organization of the Golgi apparatus in eukaryotes is dependant on microtubule trafficking, but disrupting the trafficking of Golgi elements from the endoplasmic reticulum treatment with Nocodazole (33 uM for 3 hours works) induces numerous Golgi elements to form adjacent to ER exit sites. These functional Golgi ministacks remain distrubuted about the cell, unable to track forward to form a perinuclear Golgi since Nocodazole has depolymerized the microtubules.