1
|
Meißner L, Niese L, Schüring I, Mitra A, Diez S. Human kinesin-5 KIF11 drives the helical motion of anti-parallel and parallel microtubules around each other. EMBO J 2024; 43:1244-1256. [PMID: 38424239 PMCID: PMC10987665 DOI: 10.1038/s44318-024-00048-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.
Collapse
Affiliation(s)
- Laura Meißner
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- BASS Center, Molecular Biophysics and Biochemistry Department, Yale University, 06511, New Haven, USA
| | - Lukas Niese
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Irene Schüring
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Aniruddha Mitra
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584CH, Utrecht, Netherlands
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany.
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307, Dresden, Germany.
- Cluster of Excellence Physics of Life, TUD Dresden University of Technology, 01062, Dresden, Germany.
| |
Collapse
|
2
|
Gao W, Lu J, Yang Z, Li E, Cao Y, Xie L. Mitotic Functions and Characters of KIF11 in Cancers. Biomolecules 2024; 14:386. [PMID: 38672404 PMCID: PMC11047945 DOI: 10.3390/biom14040386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 04/28/2024] Open
Abstract
Mitosis mediates the accurate separation of daughter cells, and abnormalities are closely related to cancer progression. KIF11, a member of the kinesin family, plays a vital role in the formation and maintenance of the mitotic spindle. Recently, an increasing quantity of data have demonstrated the upregulated expression of KIF11 in various cancers, promoting the emergence and progression of cancers. This suggests the great potential of KIF11 as a prognostic biomarker and therapeutic target. However, the molecular mechanisms of KIF11 in cancers have not been systematically summarized. Therefore, we first discuss the functions of the protein encoded by KIF11 during mitosis and connect the abnormal expression of KIF11 with its clinical significance. Then, we elucidate the mechanism of KIF11 to promote various hallmarks of cancers. Finally, we provide an overview of KIF11 inhibitors and outline areas for future work.
Collapse
Affiliation(s)
| | | | | | | | - Yufei Cao
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China; (W.G.); (J.L.); (Z.Y.); (E.L.)
| | - Lei Xie
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China; (W.G.); (J.L.); (Z.Y.); (E.L.)
| |
Collapse
|
3
|
Fermino do Rosário C, Wadsworth P. Measurement of Microtubule Stability in Mammalian Cells. Curr Protoc 2023; 3:e793. [PMID: 37235484 DOI: 10.1002/cpz1.793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The microtubule cytoskeleton is essential for various biological processes such as the intracellular distribution of molecules and organelles, cell morphogenesis, chromosome segregation, and specification of the location of contractile ring formation. Distinct cell types contain microtubules with different extents of stability. For example, microtubules in neurons are highly stabilized to support organelle (or vesicular) transport over large distances, and microtubules in motile cells are more dynamic. In some cases, such as the mitotic spindle, both dynamic and stable microtubules coexist. Alteration of microtubule stability is connected to disease states, making understanding microtubule stability an important area of research. Methods to measure microtubule stability in mammalian cells are described here. Together, these approaches allow microtubule stability to be measured qualitatively or semiquantitatively following staining for post-translational modifications of tubulin or treating cells with microtubule destabilizing agents such as nocodazole. Microtubule stability can also be measured quantitatively by performing fluorescence recovery after photobleaching or fluorescence photoactivation of tubulin in live cells. These methods should be helpful for those seeking to understand microtubule dynamics and stabilization. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Fixing and staining cells for tubulin post-translational modifications Basic Protocol 2: Evaluating microtubule stability following treatment with nocodazole in live or fixed cells Basic Protocol 3: Measurement of microtubule dynamic turnover by quantification of fluorescence recovery after photobleaching Basic Protocol 4: Measurement of microtubule dynamic turnover by quantification of dissipation of fluorescence after photoactivation.
Collapse
Affiliation(s)
- Carline Fermino do Rosário
- Department of Biology, University of Massachusetts Amherst, Amherst, Massachusetts
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Patricia Wadsworth
- Department of Biology, University of Massachusetts Amherst, Amherst, Massachusetts
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts
| |
Collapse
|
4
|
Husser MC, Ozugergin I, Resta T, Martin VJJ, Piekny AJ. Cytokinetic diversity in mammalian cells is revealed by the characterization of endogenous anillin, Ect2 and RhoA. Open Biol 2022; 12:220247. [PMID: 36416720 PMCID: PMC9683116 DOI: 10.1098/rsob.220247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cytokinesis is required to physically separate the daughter cells at the end of mitosis. This crucial process requires the assembly and ingression of an actomyosin ring, which must occur with high fidelity to avoid aneuploidy and cell fate changes. Most of our knowledge of mammalian cytokinesis was generated using over-expressed transgenes in HeLa cells. Over-expression can introduce artefacts, while HeLa are cancerous human cells that have lost their epithelial identity, and the mechanisms controlling cytokinesis in these cells could be vastly different from other cell types. Here, we tagged endogenous anillin, Ect2 and RhoA with mNeonGreen and characterized their localization during cytokinesis for the first time in live human cells. Comparing anillin localization in multiple cell types revealed cytokinetic diversity with differences in the duration and symmetry of ring closure, and the timing of cortical recruitment. Our findings show that the breadth of anillin correlates with the rate of ring closure, and support models where cell size or ploidy affects the cortical organization, and intrinsic mechanisms control the symmetry of ring closure. This work highlights the need to study cytokinesis in more diverse cell types, which will be facilitated by the reagents generated for this study.
Collapse
Affiliation(s)
| | - Imge Ozugergin
- Biology Department, Concordia University, Montreal, Quebec, Canada
| | - Tiziana Resta
- Biology Department, Concordia University, Montreal, Quebec, Canada
| | - Vincent J. J. Martin
- Biology Department, Concordia University, Montreal, Quebec, Canada,Center for Applied Synthetic Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa J. Piekny
- Biology Department, Concordia University, Montreal, Quebec, Canada,Center for Applied Synthetic Biology, Concordia University, Montreal, Quebec, Canada,Center for Microscopy and Cellular Imaging, Concordia University, Montreal, Quebec, Canada
| |
Collapse
|
5
|
Hao M, Zhang J, Sun M, Diao K, Wang J, Li S, Cao Q, Dai S, Mi X. TRAF4 Inhibits the Apoptosis and Promotes the Proliferation of Breast Cancer Cells by Inhibiting the Ubiquitination of Spindle Assembly-Associated Protein Eg5. Front Oncol 2022; 12:855139. [PMID: 35692762 PMCID: PMC9174544 DOI: 10.3389/fonc.2022.855139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Tumor necrosis factor receptor associated factor 4 (TRAF4) is a RING domain E3 ubiquitin ligase that mediates the ubiquitination of various proteins and plays an important role in driving tumor progression. By studying the relationship between TRAF4 and Eg5, a member of the kinesin family that plays a critical role in spindle assembly, we demonstrated that TRAF4 regulated Eg5 ubiquitination and contributed to Eg5-mediated breast cancer proliferation and inhibited breast cancer apoptosis. TRAF4 and Eg5 were both highly expressed in breast cancer and their protein level was positively correlated. Relying on its Zinc fingers domain, TRAF4 interacted with Eg5 in the cytoplasm of breast cancer cells. TRAF4 was a mitosis-related protein, and by up-regulating the protein level of Eg5 TRAF4 participated in spindle assembly. Loss of TRAF4 resulted in monopolar spindles formation, but loss of function could be rescued by Eg5. Relying on its RING domain, TRAF4 up-regulated Eg5 protein levels by inhibition of Eg5 ubiquitination, thus stabilizing Eg5 protein level during mitosis. Furthermore, we found that Smurf2, a TRAF4-targeted ubiquitination substrate, mediated the regulation of Eg5 ubiquitination by TRAF4. TRAF4 inhibited the interaction between Smurf2 and Eg5, and down-regulated the protein level of Smurf2 by promoting its ubiquitination, thereby inhibited the Smurf2-catalyzed ubiquitination of Eg5 and up-regulated Eg5 protein levels. We also demonstrate that TRAF4 plays an important role in promoting cell proliferation and in inhibiting cell apoptosis induced by Eg5. In summary, our study suggests a new direction for investigating the role of TRAF4 in driving breast cancer progression.
Collapse
Affiliation(s)
- Miaomiao Hao
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
- Department of Pathology, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jie Zhang
- Department of Pathology, School of Basic Medical Sciences, Hebei University, Baoding, China
| | - Mingfang Sun
- Department of Pathology, College of Basic Medical Sciences, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Kexin Diao
- Department of Pathology, College of Basic Medical Sciences, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Jian Wang
- Department of Pathology, College of Basic Medical Sciences, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Shiping Li
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Qixue Cao
- Department of Pathology, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Shundong Dai
- Department of Pathology, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Xiaoyi Mi
- Department of Pathology, College of Basic Medical Sciences, First Affiliated Hospital, China Medical University, Shenyang, China
- *Correspondence: Xiaoyi Mi,
| |
Collapse
|
6
|
The chirality of the mitotic spindle provides a mechanical response to forces and depends on microtubule motors and augmin. Curr Biol 2022; 32:2480-2493.e6. [PMID: 35537456 PMCID: PMC9235856 DOI: 10.1016/j.cub.2022.04.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/17/2022] [Accepted: 04/13/2022] [Indexed: 12/24/2022]
Abstract
Forces produced by motor proteins and microtubule dynamics within the mitotic spindle are crucial for proper chromosome segregation. In addition to linear forces, rotational forces or torques are present in the spindle, which are reflected in the left-handed twisted shapes of microtubule bundles that make the spindle chiral. However, the biological role and molecular origins of spindle chirality are unknown. By developing methods for measuring the spindle twist, we show that spindles are most chiral near the metaphase-to-anaphase transition. To assess the role of chirality in spindle mechanics, we compressed the spindles along their axis. This resulted in a stronger left-handed twist, suggesting that the twisted shape allows for a mechanical response to forces. Inhibition or depletion of motor proteins that perform chiral stepping, Eg5/kinesin-5, Kif18A/kinesin-8, MKLP1/kinesin-6, and dynein, decreased the left-handed twist or led to right-handed twist, implying that these motors regulate the twist by rotating microtubules within their antiparallel overlaps or at the spindle pole. A right-handed twist was also observed after the depletion of the microtubule nucleator augmin, indicating its contribution to the twist through the nucleation of antiparallel bridging microtubules. The uncovered switch from left-handed to right-handed twist reveals the existence of competing mechanisms that promote twisting in opposite directions. As round spindles are more twisted than the elongated ones are, we infer that bending and twisting moments are generated by similar molecular mechanisms and propose a physiological role for spindle chirality in allowing the spindle to absorb mechanical load. Video abstract
Spindle twist depends on torque-generating motors Eg5, Kif18A, MKLP1, and dynein Without the microtubule nucleator augmin, spindles show right-handed twist Compression of the spindle along the axis increases the left-handed twist Rounder spindles are more twisted than elongated ones are
Collapse
|
7
|
Risteski P, Jagrić M, Pavin N, Tolić IM. Biomechanics of chromosome alignment at the spindle midplane. Curr Biol 2021; 31:R574-R585. [PMID: 34033791 DOI: 10.1016/j.cub.2021.03.082] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
During metaphase, chromosomes are aligned in a lineup at the equatorial plane of the spindle to ensure synchronous poleward movement of chromatids in anaphase and proper nuclear reformation at the end of mitosis. Chromosome alignment relies on microtubules, several types of motor protein and numerous other microtubule-associated and regulatory proteins. Because of the multitude of players involved, the mechanisms of chromosome alignment are still under debate. Here, we discuss the current models of alignment based on poleward pulling forces exerted onto sister kinetochores by kinetochore microtubules, which show length-dependent dynamics and undergo poleward flux, and polar ejection forces that push the chromosome arms away from the pole. We link these models with the recent ideas based on mechanical coupling between bridging and kinetochore microtubules, where sliding of bridging microtubules promotes overlap length-dependent sliding of kinetochore fibers and thus the alignment of sister kinetochores at the spindle equator. Finally, we discuss theoretical models of forces acting on chromosomes during metaphase.
Collapse
Affiliation(s)
- Patrik Risteski
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Mihaela Jagrić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| |
Collapse
|
8
|
Jagrić M, Risteski P, Martinčić J, Milas A, Tolić IM. Optogenetic control of PRC1 reveals its role in chromosome alignment on the spindle by overlap length-dependent forces. eLife 2021; 10:61170. [PMID: 33480356 PMCID: PMC7924949 DOI: 10.7554/elife.61170] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/21/2021] [Indexed: 12/27/2022] Open
Abstract
During metaphase, chromosome position at the spindle equator is regulated by the forces exerted by kinetochore microtubules and polar ejection forces. However, the role of forces arising from mechanical coupling of sister kinetochore fibers with bridging fibers in chromosome alignment is unknown. Here, we develop an optogenetic approach for acute removal of PRC1 to partially disassemble bridging fibers and show that they promote chromosome alignment. Tracking of the plus-end protein EB3 revealed longer antiparallel overlaps of bridging microtubules upon PRC1 removal, which was accompanied by misaligned and lagging kinetochores. Kif4A/kinesin-4 and Kif18A/kinesin-8 were found within the bridging fiber and largely lost upon PRC1 removal, suggesting that these proteins regulate the overlap length of bridging microtubules. We propose that PRC1-mediated crosslinking of bridging microtubules and recruitment of kinesins to the bridging fiber promote chromosome alignment by overlap length-dependent forces transmitted to the associated kinetochore fibers. Before cells divide to create copies of themselves, they need to duplicate their genetic material. To help split their DNA evenly, they build a machine called the mitotic spindle. The mitotic spindle is made of fine, tube-like structures called microtubules, which catch the chromosomes containing the genetic information and line them up at the center of the spindle. Microtubules push and pull the chromosomes by elongating or shortening their tips. But it remains unclear how the microtubules know when the chromosomes have reached center point. One way to find out is to remove proteins that accumulate in the middle of the spindle during division, such as the protein PRC1, which helps to assemble a subset of microtubules called bridging fibers, and the proteins Kif4A and Kif18A, which work like molecular rulers, shortening long microtubules. Usually, scientists would delete one of these proteins to see what impact this has. However, these experiments take days, giving the cell enough time to adapt and thus making it difficult to study the role of each of the proteins. Here, Jagrić, Risteski, Martinčić et al. used light to manipulate proteins at the exact moment of chromosome alignment and to move PRC1 from the spindle to the cell membrane. Consequently, Kif4A and Kif18A were removed from the spindle center. This caused the bridging fibers, which overlap with the microtubules that connect to the chromosomes, to become thinner. Jagrić et al. discovered that without the molecular ruler proteins, the bridging fibers were also too long. This increased the overlap between the microtubules in the center of the spindle, causing the chromosomes to migrate away from the center. This suggests that the alignment of chromosomes in the middle of the spindle depends on the bridging microtubules, which need to be of a certain length to effectively move and keep the chromosomes at the center. Thus, forces that move the chromosomes are generated both at the tips of the microtubules and along the wall of microtubules. These results might inspire other researchers to reassess the role of bridging fibers in cell division. The optogenetic technique described here could also help to determine the parts other proteins have to play. Ultimately, this might allow researchers to identify all the proteins needed to align the chromosomes.
Collapse
Affiliation(s)
- Mihaela Jagrić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Patrik Risteski
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Jelena Martinčić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Ana Milas
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| |
Collapse
|
9
|
Pavin N, Tolić IM. Mechanobiology of the Mitotic Spindle. Dev Cell 2020; 56:192-201. [PMID: 33238148 DOI: 10.1016/j.devcel.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/06/2020] [Accepted: 11/02/2020] [Indexed: 10/22/2022]
Abstract
The mitotic spindle is a microtubule-based assembly that separates the chromosomes during cell division. As the spindle is basically a mechanical micro machine, the understanding of its functioning is constantly motivating the development of experimental approaches based on mechanical perturbations, which are complementary to and work together with the classical genetics and biochemistry methods. Recent data emerging from these approaches in combination with theoretical modeling led to novel ideas and significant revisions of the basic concepts in the field. In this Perspective, we discuss the advances in the understanding of spindle mechanics, focusing on microtubule forces that control chromosome movements.
Collapse
Affiliation(s)
- Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| |
Collapse
|
10
|
Fang CT, Kuo HH, Hsu SC, Yih LH. HSP70 regulates Eg5 distribution within the mitotic spindle and modulates the cytotoxicity of Eg5 inhibitors. Cell Death Dis 2020; 11:715. [PMID: 32873777 PMCID: PMC7462862 DOI: 10.1038/s41419-020-02919-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 02/06/2023]
Abstract
The heat shock protein 70 (HSP70) is a conserved molecular chaperone and proteostasis regulator that protects cells from pharmacological stress and promotes drug resistance in cancer cells. In this study, we found that HSP70 may promote resistance to anticancer drugs that target the mitotic kinesin, Eg5, which is essential for assembly and maintenance of the mitotic spindle and cell proliferation. Our data show that loss of HSP70 activity enhances Eg5 inhibitor-induced cytotoxicity and spindle abnormalities. Furthermore, HSP70 colocalizes with Eg5 in the mitotic spindle, and inhibition of HSP70 disrupts this colocalization. Inhibition or depletion of HSP70 also causes Eg5 to accumulate at the spindle pole, altering microtubule dynamics and leading to chromosome misalignment. Using ground state depletion microscopy followed by individual molecule return (GSDIM), we found that HSP70 inhibition reduces the size of Eg5 ensembles and prevents their localization to the inter-polar region of the spindle. In addition, bis(maleimido)hexane-mediated protein-protein crosslinking and proximity ligation assays revealed that HSP70 inhibition deregulates the interaction between Eg5 tetramers and TPX2 at the spindle pole, leading to their accumulation in high-molecular-weight complexes. Finally, we showed that the passive substrate-binding activity of HSP70 is required for appropriate Eg5 distribution and function. Together, our results show that HSP70 substrate-binding activity may regulate proper assembly of Eg5 ensembles and Eg5-TPX2 complexes to modulate mitotic distribution/function of Eg5. Thus, HSP70 inhibition may sensitize cancer cells to Eg5 inhibitor-induced cytotoxicity.
Collapse
Affiliation(s)
- Chieh-Ting Fang
- Department of Life Science, National Taiwan University, Taipei, Taiwan.,Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hsiao-Hui Kuo
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Shao-Chun Hsu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Ling-Huei Yih
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
| |
Collapse
|