Microtubule Mass Research Articles

Mechanisms of minor pole-mediated spindle bipolarization in human oocytes.

Spindle bipolarization, the process of a microtubule mass transforming into a bipolar spindle, is a prerequisite for accurate chromosome segregation. In contrast to mitotic cells, the process and mechanism of spindle bipolarization in human oocytes remains unclear. Using high-resolution imaging in more than 1800 human oocytes, we revealed a typical state of multipolar intermediates that form during spindle bipolarization and elucidated the mechanism underlying this process. We found that the minor poles formed in multiple kinetochore clusters contribute to the generation of multipolar intermediates. We further determined the essential roles of HAUS6, KIF11, and KIF18A in spindle bipolarization and identified mutations in these genes in infertile patients characterized by oocyte or embryo defects. These results provide insights into the physiological and pathological mechanisms of spindle bipolarization in human oocytes.

P-248 The meiotic spindle is preserved during freezing but post-thawing rehydration causes its destabilization in human eggs

Abstract Study question Is the human egg spindle integrity impaired by vitrification and thawing procedures? Summary answer Cryoprotective-caused dehydration stabilizes the MII spindle, but the re-entry of water during thawing induces depolymerization of microtubules, thus promoting instability of the division apparatus. What is known already Freezing sperm and preimplantation embryos have become routine IVF procedures with excellent clinical results, whereas cryopreservation of oocytes remains problematic. The major factor underlying the human oocytés notorious propensity to cryoinjury is the temperature sensitivity of the meiotic spindle, the fidelity of which is critical for faithful post-fertilization development. Most studies focus on evaluating vitrified-thawed oocytes' post-fertilization outcome, but behavior of the meiotic spindle during the freezing process has received only a little attention. Study design, size, duration The experimental study involved a total of 165 human oocytes donated for research. The presence and morphology of the meiotic spindle were examined by polarized light microscopy (PLM) and fluorescent confocal imaging to map out the MII spindle dynamics during the vitrification-thawing procedure. Participants/materials, setting, methods A total of 114 women gave informed consent for their surplus immature oocytes to be used in this project. Oocytes that completed maturation in vitro were subjected to spindle imaging (Oosight) and vitrified using a Kitazato/Cryotop open system. The PLM-positive/negative oocytes were fixed at 6 steps of the vitrification-thawing protocol and 2 hours after thawing (15 oocytes in each subgroup). Microtubules and DNA were fluorescently labeled to inspect chromosome-spindle configuration. Main results and the role of chance Time-course experiments showed that PLM-detectable bipolar spindle remained intact in all but one oocyte (44/45) fixed during pre-vitrification equilibration. Notably, the PLM signal became more prominent after adding a cryoprotectant that displaced intracellular water. In contrast, the MII spindle signal progressively disappeared during thawing. Specific tubulin labeling revealed that the microtubule mass was still present in most (41/45) oocytes from the vitrified-thawed sample group. However, the division apparatus tended to lose its bipolarity and disintegrate (8/45) during the washing steps. This trend was accented in the group of oocytes that lacked PLM-detectable spindles before freezing. Here, only a minority of cells (11/45) undergoing rehydration displayed characteristic chromosome-spindle configuration. The difference in eggś capability to ensure spindle bipolarity was apparent even 2 hours after thawing when 13/15 of initially PLM-positive but only 7/15 PLM-negative oocytes exhibited normal-shaped spindles. Based on these data, we hypothesize that the transient disappearance of the PLM spindle signal during warming may be attributed to the restoration of microtubule dynamics and spindle destabilization. The speed and efficiency of spindle reconstruction seem to depend on the overall egǵs fitness. Limitations, reasons for caution This research study involved a limited number of hormonally-primed oocytes that extruded a polar body in vitro shortly after retrieval. The obtained imaging data represent snapshots of the process. A technically challenging live imaging study is needed to complement the description of the oocyte spindle dynamics during post-vitrification recovery. Wider implications of the findings Our results demonstrate that meiotic spindles in frozen-thawed eggs are not products of de novo spindle assembly but are built on preexisting microtubule mass. Suboptimal handling and reducing the interval between thawing and ICSI may enhance unavoidable spindle instability and thus compromise the developmental potential of vitrified eggs. Trial registration number not-applicable

Fidgetin impacts axonal growth and branching in a local mTOR signal dependent manner.

Neurons require a constant increase in protein synthesis during axonal growth and regeneration. AKT-mTOR is a central pathway for mammalian cell survival and regeneration. Fidgetin (Fign) is an ATP-dependent microtubule (MT)-severing enzyme whose functions are associated with neurite outgrowth, axon regeneration and cell migration. Although most previous studies have indicated that depletion of Fign is involved in those biological activities by increasing labile MT mass, it remains unknown whether mTOR activation contributes to this process. Here, we showed that depletion of Fign enhanced p-mTOR/p-S6K activation, and the mTOR inhibitor Rapamycin inhibited axon outgrowth and p-rpS6 activation. We then investigated the effects of neuronal-specific Fign deletion in a rat spinal cord hemisection model by injecting syn-GFP Fign shRNA virus. BBB values revealed an improvement in functional recovery. The p-mTOR was activated along with neuronal Fign depletion. The syn-mCherry virus showed more sprouting neurites entering the injury region, which was confirmed by immunostaining GAP43 protein. Further, we showed that Fign siRNA treatment promoted axon outgrowth and branching, whose underlying mechanism was firstly attributed to local activation of the mTOR pathway, and increased MT dynamicity. Finally, considering L-leucine, promotes axonal growth and neuronal survival, we applied L-leucine with Fign depletion after spinal cord injury or in chondroitin sulfate proteoglycan inhibitory molecules. The phenomenon of synergistically augmented axon regeneration was observed. In summary, our results indicated a novel local mTOR pathway for fidgetin to impact axon growth and provided a combined strategy in SCI.

Combretastatin Derivatives as Microtubule Inhibitors of Colchicines Binding Site

: The colchicine binding site in microtubules is the most flourishing target for anti-cancer treatment. Microtubule inhibitor drugs, including paclitaxel and vinca alkaloids, have been considered to exert their activity primarily by increasing or decreasing the cellular micro-tubule mass. This review describes the microtubular assembly along with the combretastatin de-rivatives as microtubules inhibitors, the structures of compounds known to interact with colchi-cines binding sites, and their possible mechanism of action. Additionally, the utility of other heterocyclic rings and their combretastatin derivatives in treating cancer is also discussed. Col-chicines binding site represents a stimulating new molecular target in the design of com-bretastatin drugs.

Spastin accumulates on shrinking microtubule tips by slowing them down

The microtubule-severing enzyme spastin is an important regulator of microtubule dynamics and its mutation is implicated in hereditary spastic paraplegia. In addition to severing microtubules, spastin also slows their depolymerization and promotes their transition from shrinkage to growth (rescue). This activity, in combination with severing, can lead to the amplification of microtubule number and mass. The effects of spastin on microtubule dynamics may be enhanced by its observed accumulation on the tips of shrinking microtubules, but the mechanism of tip accumulation is unclear.

The Xenopus spindle is as dense as the surrounding cytoplasm.

The mitotic spindle is a self-organizing molecular machine, where hundreds of different molecules continuously interact to maintain a dynamic steady state. While our understanding of key molecular players in spindle assembly is significant, it is still largely unknown how the spindle's material properties emerge from molecular interactions. Here, we use correlative fluorescence imaging and label-free three-dimensional optical diffraction tomography (ODT) to measure the Xenopus spindle's mass density distribution. While the spindle has been commonly referred to as a denser phase of the cytoplasm, we find that it has the same density as its surrounding, which makes it neutrally buoyant. Molecular perturbations suggest that spindle mass density can be modulated by tuning microtubule nucleation and dynamics. Together, ODT provides direct, unbiased, and quantitative information of the spindle's emergent physical properties-essential to advance predictive frameworks of spindle assembly and function.

Differences in Intrinsic Tubulin Dynamic Properties Contribute to Spindle Length Control in Xenopus Species.

The function of cellular organelles relates not only to their molecular composition but also to their size. However, how the size of dynamic mesoscale structures is established and maintained remains poorly understood [1-3]. Mitotic spindle length, for example, varies several-fold among cell types and among different organisms [4]. Although most studies on spindle size control focus on changes in proteins that regulate microtubule dynamics [5-8], the contribution of the spindle's main building block, the αβ-tubulin heterodimer, has yet to be studied. Apart from microtubule-associated proteins and motors, two factors have been shown to contribute to the heterogeneity of microtubule dynamics: tubulin isoform composition [9, 10] and post-translational modifications [11]. In the past, studying the contribution of tubulin and microtubules to spindle assembly has been limited by the fact that physiologically relevant tubulins were not available. Here, we show that tubulins purified from two closely related frogs, Xenopus laevis and Xenopus tropicalis, have surprisingly different microtubule dynamics invitro. X.laevis microtubules combine very fast growth and infrequent catastrophes. In contrast, X.tropicalis microtubules grow slower and catastrophe more frequently. We show that spindle length and microtubule mass can be controlled by titrating the ratios of the tubulins from the two frog species. Furthermore, we combine our invitro reconstitution assay and egg extract experiments with computational modeling to show that differences in intrinsic properties of different tubulins contribute to the control of microtubule mass and therefore set steady-state spindle length.

Effects of Severing Enzymes on the Length Distribution and Total Mass of Microtubules

Microtubules are cytoskeletal polymers of αβ-tubulin whose dynamics is highly regulated as eukaryotic cells undergo cell division, migration and tissue development. Microtubule severing enzymes, spastin, katanin and fidgetin use ATP-hydrolysis to fragment microtubules into shorter filaments. Paradoxically, in vivo experiments have shown that severases can increase total microtubule number and mass inside the cells, suggesting that severases possess a nucleation-like activity. We have resolved this paradox by reconstituting a dynamic microtubule severing system in vitro and discovered that Drosophila spastin has two additional properties in addition to severing: it increases microtubule rescue and slows down shrinkage. Under the right circumstances these effects lead to an exponential increase in the number and mass of microtubules. In this abstract, we address the question of how the exponential rate constant and the length distribution depend on severing and microtubule dynamics. A mathematical model reveals that the amplification rate depends on the balance of creating new microtubules through severing and the loss of existing microtubule through shrinkage. The mean length depends on the ratio of the growth rate to the severing rate and can be well-approximated by a simplified no-catastrophe model, which we have solved analytically. Unexpectedly, dynamic instability has only a small impact on microtubule length. On the other hand, dynamic instability can influence the amplification rate. Thus differential regulation of the dynamic parameters can separately modulate different aspects of the microtubule network. Our results establish the quantitative basis for how severing and dynamics conjunctly constitute a versatile mechanism to regulate microtubule length and mass in the complex cellular environment.

Predicted Effects of Severing Enzymes on the Length Distribution and Total Mass of Microtubules

Microtubules are dynamic cytoskeletal polymers whose growth and shrinkage are highly regulated as eukaryotic cells change shape, move, and divide. One family of microtubule regulators includes the ATP-hydrolyzing enzymes spastin, katanin, and fidgetin, which sever microtubule polymers into shorter fragments. Paradoxically, severases can increase microtubule number and mass in cells. Recent work with purified spastin and katanin accounts for this phenotype by showing that, in addition to severing, these enzymes modulate microtubule dynamics by accelerating the conversion of microtubules from their shrinking to their growing states and thereby promoting their regrowth. This leads to the observed exponential increase in microtubule mass. Spastin also influences the steady-state distribution of microtubule lengths, changing it from an exponential, as predicted by models of microtubule dynamic instability, to a peaked distribution. This effect of severing and regrowth by spastin on the microtubule length distribution has not been explained theoretically. To solve this problem, we formulated and solved a master equation for the time evolution of microtubule lengths in the presence of severing and microtubule dynamic instability. We then obtained numerical solutions to the steady-state length distribution and showed that the rate of severing and the speed of microtubule growth are the dominant parameters determining the steady-state length distribution. Furthermore, we found that the amplification rate is predicted to increase with severing, which is, to our knowledge, a new result. Our results establish a theoretical basis for how severing and dynamics together can serve to nucleate new microtubules, constituting a versatile mechanism to regulate microtubule length and mass.

Spastin is a dual-function enzyme that severs microtubules and promotes their regrowth to increase the number and mass of microtubules

The remodeling of the microtubule cytoskeleton underlies dynamic cellular processes, such as mitosis, ciliogenesis, and neuronal morphogenesis. An important class of microtubule remodelers comprises the severases-spastin, katanin, and fidgetin-which cut microtubules into shorter fragments. While severing activity might be expected to break down the microtubule cytoskeleton, inhibiting these enzymes in vivo actually decreases, rather increases, the number of microtubules, suggesting that severases have a nucleation-like activity. To resolve this paradox, we reconstituted Drosophila spastin in a dynamic microtubule assay and discovered that it is a dual-function enzyme. In addition to its ATP-dependent severing activity, spastin is an ATP-independent regulator of microtubule dynamics that slows shrinkage and increases rescue. We observed that spastin accumulates at shrinking ends; this increase in spastin concentration may underlie the increase in rescue frequency and the slowdown in shortening. The changes in microtubule dynamics promote microtubule regrowth so that severed microtubule fragments grow, leading to an increase in the number and mass of microtubules. A mathematical model shows that spastin's effect on microtubule dynamics is essential for this nucleation-like activity: spastin switches microtubules into a state where the net flux of tubulin onto each polymer is positive, leading to the observed exponential increase in microtubule mass. This increase in the microtubule mass accounts for spastin's in vivo phenotypes.

Severing Enzymes Amplify Microtubule Arrays through Lattice GTP-Tubulin Incorporation

Spastin and katanin sever and destabilize microtubules. Their mutation causes debilitating diseases. Paradoxically, despite their destructive activity they increase microtubule mass in spindles, plant cortical arrays and neurons. Combining electron and single-molecule TIRF microscopy we show that the elemental step in microtubule-severing is the generation of nanoscale damage throughout the microtubule by active extraction of tubulin heterodimers. These damage sites are repaired spontaneously by GTP-tubulin incorporation. As a result, the microtubule shaft is rejuvenated with GTP-tubulin islands that stabilize it against depolymerization and newly severed ends emerge with a high-density of GTP-tubulin that protects against depolymerization. Consequently, spastin and katanin increase microtubule rescue frequency without affecting growth rates and catastrophe. The stabilization of the newly severed plus-ends and the higher rescue frequency synergize to amplify microtubule number and mass. Thus, severing enzymes regulate microtubule architecture and dynamics by promoting GTP-tubulin incorporation within the microtubule shaft.

Knockdown of Fidgetin Improves Regeneration of Injured Axons by a Microtubule-Based Mechanism.

Fidgetin is a microtubule-severing protein that pares back the labile domains of microtubules in the axon. Experimental depletion of fidgetin results in elongation of the labile domains of microtubules and faster axonal growth. To test whether fidgetin knockdown assists axonal regeneration, we plated dissociated adult rat DRGs transduced using AAV5-shRNA-fidgetin on a laminin substrate with spots of aggrecan, a growth-inhibitory chondroitin sulfate proteoglycan. This cell culture assay mimics the glial scar formed after CNS injury. Aggrecan is more concentrated at the edge of the spot, such that axons growing from within the spot toward the edge encounter a concentration gradient that causes growth cones to become dystrophic and axons to retract or curve back on themselves. Fidgetin knockdown resulted in faster-growing axons on both laminin and aggrecan and enhanced crossing of axons from laminin onto aggrecan. Strikingly, axons from within the spot grew more avidly against the inhibitory aggrecan concentration gradient to cross onto laminin, without retracting or curving back. We also tested whether depleting fidgetin improves axonal regeneration in vivo after a dorsal root crush in adult female rats. Whereas control DRG neurons failed to extend axons across the dorsal root entry zone after injury, DRG neurons in which fidgetin was knocked down displayed enhanced regeneration of axons across the dorsal root entry zone into the spinal cord. Collectively, these results establish fidgetin as a novel therapeutic target to augment nerve regeneration and provide a workflow template by which microtubule-related targets can be compared in the future.SIGNIFICANCE STATEMENT Here we establish a workflow template from cell culture to animals in which microtubule-based treatments can be tested and compared with one another for their effectiveness in augmenting regeneration of injured axons relevant to spinal cord injury. The present work uses a viral transduction approach to knock down fidgetin from rat neurons, which coaxes nerve regeneration by elevating microtubule mass in their axons. Unlike previous strategies using microtubule-stabilizing drugs, fidgetin knockdown adds microtubule mass that is labile (rather than stable), thereby better recapitulating the growth status of a developing axon.

Severing to build microtubules

Cytoskeleton![Figure][1] New tubulin (pink) patches small holes in microtubule lattices made by severing enzymes (purple). CREDIT: JANET IWASA Microtubules are essential intracellular polymers, built from tubulin subunits, that establish cell shape, move organelles, and segregate chromosomes during cell division. Vemu et al. show that microtubule-severing enzymes extract tubulin subunits along the microtubule shaft. This nanoscale damage is repaired by the incorporation of free tubulin, which stabilizes the microtubule against depolymerization. When extraction outpaces repair, microtubules are severed, emerging with stabilized ends composed of fresh tubulin. The severed microtubules act as templates for new microtubule growth, leading to amplification of microtubule number and mass. Thus, seemingly paradoxically, severing enzymes can increase microtubule mass in processes such as neurogenesis and mitotic spindle assembly. Science , this issue p. [eaau1504][2] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aau1504

Severing enzymes amplify microtubule arrays through lattice GTP-tubulin incorporation.

Spastin and katanin sever and destabilize microtubules. Paradoxically, despite their destructive activity they increase microtubule mass in vivo. We combined single-molecule total internal reflection fluorescence microscopy and electron microscopy to show that the elemental step in microtubule severing is the generation of nanoscale damage throughout the microtubule by active extraction of tubulin heterodimers. These damage sites are repaired spontaneously by guanosine triphosphate (GTP)-tubulin incorporation, which rejuvenates and stabilizes the microtubule shaft. Consequently, spastin and katanin increase microtubule rescue rates. Furthermore, newly severed ends emerge with a high density of GTP-tubulin that protects them against depolymerization. The stabilization of the newly severed plus ends and the higher rescue frequency synergize to amplify microtubule number and mass. Thus, severing enzymes regulate microtubule architecture and dynamics by promoting GTP-tubulin incorporation within the microtubule shaft.

Tau Does Not Stabilize Axonal Microtubules but Rather Enables Them to Have Long Labile Domains

It is widely believed that tau stabilizes microtubules in the axon [1-3] and, hence, that disease-induced loss of tau from axonal microtubules leads to their destabilization [3-5]. An individual microtubule in the axon has a stable domain and a labile domain [6-8]. We found that tau is more abundant on the labile domain, which is inconsistent with tau's proposed role as a microtubule stabilizer. When tauis experimentally depleted from cultured rat neurons, the labile microtubule mass of the axon drops considerably, the remaining labile microtubule mass becomes less labile, and the stable microtubule mass increases. MAP6 (also called stable tubule-only polypeptide), which is normally enriched on the stable domain [9], acquires a broader distribution across the microtubule when tau is depleted, providing a potential explanation for the increase in stable microtubule mass. When MAP6 is depleted, the labile microtubule mass becomes even more labile, indicating that, unlike tau, MAP6 is a genuine stabilizer of axonal microtubules. We conclude that tau is not a stabilizer of axonal microtubules but is enriched on the labile domain of the microtubule to promote its assembly while limiting the binding to it of genuine stabilizers, such as MAP6. This enables the labile domain to achieve great lengths without being stabilized. These conclusions are contrary to tau dogma.

Microtubule defects in mesenchymal stromal cells distinguish patients with Progressive Supranuclear Palsy

Progressive Supranuclear Palsy (PSP) is a rare neurodegenerative disease whose etiopathogenesis remains elusive. The intraneuronal accumulation of hyperphosphorylated Tau, a pivotal protein in regulating microtubules (MT), leads to include PSP into tauopathies. Pathological hallmarks are well known in neural cells but no word yet if PSP‐linked dysfunctions occur also in other cell types. We focused on bone marrow mesenchymal stromal cells (MSCs) that have recently gained attention for therapeutic interventions due to their anti‐inflammatory, antiapoptotic and trophic properties. Here, we aimed to investigate MSCs biology and to disclose if any disease‐linked defect occurs in this non‐neuronal compartment. First, we found that cells obtained from patients showed altered morphology and growth. Next, Western blotting analysis unravelled the imbalance in α‐tubulin post‐translational modifications and in MT stability. Interestingly, MT mass is significantly decreased in patient cells at baseline and differently changes overtime compared to controls, suggesting their inability to efficiently remodel MT cytoskeleton during ageing in culture. Thus, our results provide the first evidence that defects in MT regulation and stability occur and are detectable in a non‐neuronal compartment in patients with PSP. We suggest that MSCs could be a novel model system for unravelling cellular processes implicated in this neurodegenerative disorder.

Nanoparticle Delivery of Fidgetin siRNA as a Microtubule-based Therapy to Augment Nerve Regeneration

Microtubule-stabilizing drugs have gained popularity for treating injured adult axons, the rationale being that increased stabilization of microtubules will prevent the axon from retracting and fortify it to grow through inhibitory molecules associated with nerve injury. We have posited that a better approach would be not to stabilize the microtubules, but to increase labile microtubule mass to levels more conducive to axonal growth. Recent work on fetal neurons suggests this can be accomplished using RNA interference to reduce the levels of fidgetin, a microtubule-severing protein. Methods to introduce RNA interference into adult neurons, in vitro or in vivo, have been problematic and not translatable to human patients. Here we show that a novel nanoparticle approach, previously shown to deliver siRNA into tissues and organs, enables siRNA to gain entry into adult rat dorsal root ganglion neurons in culture. Knockdown of fidgetin is partial with this approach, but sufficient to increase the labile microtubule mass of the axon, thereby increasing axonal growth. The increase in axonal growth occurs on both a favorable substrate and a growth-inhibitory molecule associated with scar formation in injured spinal cord. The nanoparticles are readily translatable to in vivo studies on animals and ultimately to clinical applications.

Mechanics of Blood Cells with Marginal Band: Competition between Cortical Tension and Rigidity

The fast blood stream of animals is associated with large shear stresses. Consequently, blood cells have evolved a special morphology and a specific internal architecture allowing them to maintain their integrity over several weeks. Non-mammalian red blood cells, mammalian erythroblasts and platelets in particular have a peripheral ring of microtubules, called the marginal band, that flattens the overall cell morphology by pushing on the cell cortex. We modeled how the shape of these cells stems from the competition between marginal band elasticity and cortical tension. We predict that the diameter of the cell scales with the total microtubule mass, and verify the predicted law across a wide range of species. Our analysis also shows that the combination of the marginal band rigidity and cortical tension increases the ability of the cell to withstand forces without buckling. Eventually, we show that the buckling of the marginal band observed during platelet activation is caused by a rapid increase of the cortical tension.

Microtubules in health and degenerative disease of the nervous system.

Microtubules are essential for the development and maintenance of axons and dendrites throughout the life of the neuron, and are vulnerable to degradation and disorganization in a variety of neurodegenerative diseases. Microtubules, polymers of tubulin heterodimers, are intrinsically polar structures with a plus end favored for assembly and disassembly and a minus end less favored for these dynamics. In the axon, microtubules are nearly uniformly oriented with plus ends out, whereas in dendrites, microtubules have mixed orientations. Microtubules in developing neurons typically have a stable domain toward the minus end and a labile domain toward the plus end. This domain structure becomes more complex during neuronal maturation when especially stable patches of polyaminated tubulin become more prominent within the microtubule. Microtubules are the substrates for molecular motor proteins that transport cargoes toward the plus or minus end of the microtubule, with motor-driven forces also responsible for organizing microtubules into their distinctive polarity patterns in axons and dendrites. A vast array of microtubule-regulatory proteins impart direct and indirect changes upon the microtubule arrays of the neuron, and these include microtubule-severing proteins as well as proteins responsible for the stability properties of the microtubules. During neurodegenerative diseases, microtubule mass is commonly diminished, and the potential exists for corruption of the microtubule polarity patterns and microtubule-mediated transport. These ill effects may be a primary causative factor in the disease or may be secondary effects, but regardless, therapeutics capable of correcting these microtubule abnormalities have great potential to improve the status of the degenerating nervous system.

LG308, a Novel Synthetic Compound with Antimicrotubule Activity in Prostate Cancer Cells, Exerts Effective Antitumor Activity.

Microtubule plays many different essential roles in the process of tumorigenesis in many eukaryotes, and targeting mitotic progression by disturbing microtubule dynamics is used as a common strategy for cancer treatment. Microtubule-targeted drugs, including paclitaxel and Vinca alkaloids, were previously considered to work primarily by increasing or decreasing the cellular microtubule mass. The tubulin/microtubule system, which is an integral component of the cytoskeleton, is a therapeutic target for prostate cancer. In this study, we found a novel synthetic compound, 8-fluoro-N-phenylacetyl-1, 3, 4, 9-tetrahydro-β-carboline (LG308), which disrupted the microtubule organization via inhibiting the polymerization of microtubule in PC-3M and LNCaP prostate cancer cell lines. Further study proved that LG308 induced mitotic phase arrest and inhibited G2/M progression significantly in LNCaP and PC-3M cell lines in a dose-dependent manner, and these were associated with the upregulation of cyclin B1 and mitotic marker MPM-2 and the dephosphorylation of cdc2. Besides, the cell proliferation and colony formation of PC-3M and LNCaP cells were effectively inhibited by LG308. Furthermore, LG308 induced apoptosis and cell death in PC-3M and LNCaP cell lines in vitro. In vivo, LG308 dramatically suppressed the growth and metastasis of prostate cancer in both xenograft and orthotopic models. All these data indicate that LG308 is a promising anticancer candidate with antimitotic activity for the treatment of prostate cancer.