Forced expression of a dominant‐negative chimeric tropomyosin causes abnormal motile behavior during cell division

Wong, Karen; Wessels, Deborah; Krob, Sonja L.; Matveia, Amanda R.; Lin, Jin-Lung; Soll, David R.; Lin, Jim Jung‐Ching

doi:10.1002/(sici)1097-0169(200002)45:2<121::aid-cm4>3.0.co;2-#

Cited by 21 publications

(10 citation statements)

References 41 publications

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“…Consistent with our observations, coincident with the morphological changes in the transformed fibroblasts, CaD was reported to become specifically localized in the cell surface blebs [39], suggesting a possible involvement of CaD in the control of bleb formation. The blebs found in dividing CaD39-6F-expressing cells are different from those found in the chimeric tropomyosin hTM5/3-expressing cells that we have previously characterized [34]. Compared to the small and numerous blebs in 39-6FC33 cells, the blebs formed in the hTM5/3-overexpressing cells were larger yet less frequent.…”

Section: Discussioncontrasting

confidence: 70%

“…Compared to the small and numerous blebs in 39-6FC33 cells, the blebs formed in the hTM5/3-overexpressing cells were larger yet less frequent. In addition to bleb formation, the hTM5/3-overexpressing cells usually had difficulties in defining the position of the cleavage furrow, resulting in the twisting of the mitotic cells and the detachment of one of the evolving daughter cells during cytokinesis [34]. In contrast, the CaD39-6F-overexpressing cells do not have this problem and have almost equally divided daughter cells with many small blebs.…”

Section: Discussionmentioning

confidence: 99%

“…Cell dynamics during mitosis were analyzed using the 2D-DIAS program [31 -33] as previously described [17,34]. Briefly, a coverslip on which cells were grown was transferred to a Dvorak-Stotler perfusion chamber (Lucas-Highland, Chantilly, Va.) positioned on a microscope stage prewarmed to 35°C.…”

Section: D-dias Analysis Of Mitotic Cells Expressing Cad39-6fmentioning

confidence: 99%

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Regulation of caldesmon activity by Cdc2 kinase plays an important role in maintaining membrane cortex integrity during cell division

Li¹,

Wessels²,

Wang³

et al. 2003

Cellular and Molecular Life Sciences (CMLS)

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To study the mitosis-specific phosphorylation of caldesmon (CaD), we generated a mutant of the C-terminal fragment (amino acids 244-538) of human fibroblast CaD (CaD39-6F), as well as a mutant of the full-length CaD (CaD-6F), in which all six potential phosphorylation sites for Cdc2 kinase were abolished. The mitotic CaD39-6F-overexpressing cells required more time to progress from anaphase start to 50% cytokinesis, exhibited larger size, and abnormally formed numerous small blebs. In contrast, overexpression of the wild-type C-terminal fragment of CaD (CaD39) did not result in abnormal bleb formation, but led to larger size and prolonged the time requirement between anaphase start and 50% cytokinesis. Similar abnormal blebs were also observed in the CaD-6F-overexpressing cells. CaD-6F-overexpressing cells did not show larger size but required more time to progress from anaphase start to 50% cytokinesis. These results suggest that mitosis-specific phosphorylation of CaD plays a role in inhibiting bleb formation and that the N-terminal fragment of CaD is required for cell size determination.

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Section: Discussioncontrasting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Regulation of caldesmon activity by Cdc2 kinase plays an important role in maintaining membrane cortex integrity during cell division

Li¹,

Wessels²,

Wang³

et al. 2003

Cellular and Molecular Life Sciences (CMLS)

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“…These data suggest that the exact matching of the N and C termini is essential for normal functioning of TMs (48). Further work showed that the hTM5/3 chimeras induce altered motile behavior during the cytokinesis (56). These workers suggested the stronger binding of the chimeras with actin (57) would differentially regulate the contractile ring than would the wild type TMs.…”

Section: Discussionmentioning

confidence: 98%

“…These workers suggested the stronger binding of the chimeras with actin (57) would differentially regulate the contractile ring than would the wild type TMs. The defective cytokinesis could be the consequence of a generation of much higher force for separating daughter cells through interaction between the chimeras and actin than that produced by the wild type proteins (56). Because HA-TM1 interacts poorly with actin, HA-TM1 binding could yield lower than necessary force and hence delay the cytokinesis.…”

Section: Discussionmentioning

confidence: 99%

N Terminus Is Essential for Tropomyosin Functions

Bharadwaj

Hitchcock‐DeGregori

Thorburn

et al. 2004

Journal of Biological Chemistry

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Down-regulation of several key actin-binding proteins, such as ␣-actinin, vinculin, gelsolin, and tropomyosins (TMs), is considered to contribute to the disorganized cytoskeleton present in many neoplastic cells. TMs stabilize actin filaments against the gel severing actions of proteins such as cofilin. Among multiple TMs expressed in non-muscle cells, tropomyosin-1 (TM1) isoform induces stress fibers and functions as a suppressor of malignant transformation. However, the molecular mechanisms of TM1-mediated cytoskeletal effects and tumor suppression remain poorly understood. We have hypothesized that the ability of TM1 to stabilize microfilaments is crucial for tumor suppression. In this study, by employing a variant TM1, which contains an N-terminal hemagglutinin epitope tag, we demonstrate that the N terminus is a key determinant of tropomyosin-1 function. Unlike the wild type TM1, the modified protein fails to restore stress fibers and inhibit anchorage-independent growth in transformed cells. Furthermore, the N-terminal modification of TM1 disorganizes the cytoskeleton and delays cytokinesis in normal cells, abolishes binding to F-actin, and disrupts the dimeric associations in vivo. The functionally defective TM1 allows the association of cofilin to stress fibers and disorganizes the microfilaments, whereas wild type TM1 appears to restrict the binding of cofilin to stress fibers. TM1-induced cytoskeletal reorganization appears to be mediated through preventing cofilin interaction with microfilaments. Our studies provide in vivo functional evidence that the N terminus is a critical determinant of TM1 functions, which in turn determines the organization of stress fibers.

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High‐molecular‐weight tropomyosins localize to the contractile rings of dividing CNS cells but are absent from malignant pediatric and adult CNS tumors

Hughes

Cooke‐Yarborough

Chadwick

et al. 2003

Glia

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Tropomyosin has been implicated in the control of actin filament dynamics during cell migration, morphogenesis, and cytokinesis. In order to gain insight into the role of tropomyosins in cell division, we examined their expression in developing and neoplastic brain tissue. We found that the high-molecular-weight tropomyosins are downregulated at birth, which correlates with glial cell differentiation and withdrawal of most cells from the cell cycle. Expression of these isoforms was restricted to proliferative areas in the embryonic brain and was absent from the adult, where the majority of cells are quiescent. However, they were induced under conditions where glial cells became proliferative in response to injury. During cytokinesis, these tropomyosin isoforms were associated with the contractile ring. We also investigated tropomyosin expression in neoplastic CNS tissues. Low-grade astrocytic tumors expressed high-molecular-weight tropomyosins, while highly malignant CNS tumors of diverse origin did not (P

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Forced expression of a dominant‐negative chimeric tropomyosin causes abnormal motile behavior during cell division

Cited by 21 publications

References 41 publications

Regulation of caldesmon activity by Cdc2 kinase plays an important role in maintaining membrane cortex integrity during cell division

Regulation of caldesmon activity by Cdc2 kinase plays an important role in maintaining membrane cortex integrity during cell division

N Terminus Is Essential for Tropomyosin Functions

High‐molecular‐weight tropomyosins localize to the contractile rings of dividing CNS cells but are absent from malignant pediatric and adult CNS tumors

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