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Coordinating cytoskeletal tracks to polarize cellular movements.

Kodama A, Lechler T, Fuchs E - J. Cell Biol. (2004)

Bottom Line: For many years after the discovery of actin filaments and microtubules, it was widely assumed that their polymerization, organization, and functions were largely distinct.However, in recent years it has become increasingly apparent that coordinated interactions between microtubules and filamentous actin are involved in many polarized processes, including cell shape, mitotic spindle orientation, motility, growth cone guidance, and wound healing.In the past few years, significant strides have been made in unraveling the intricacies that govern these intertwined cytoskeletal rearrangements.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.

ABSTRACT
For many years after the discovery of actin filaments and microtubules, it was widely assumed that their polymerization, organization, and functions were largely distinct. However, in recent years it has become increasingly apparent that coordinated interactions between microtubules and filamentous actin are involved in many polarized processes, including cell shape, mitotic spindle orientation, motility, growth cone guidance, and wound healing. In the past few years, significant strides have been made in unraveling the intricacies that govern these intertwined cytoskeletal rearrangements.

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Related in: MedlinePlus

Schematic view of cortical platform formation, maturation, and function. Cortical platforms are localized membrane-associated sites that develop into a rich molecular center for the convergence of transmembrane receptors, signal transduction proteins, actin polymerization machinery, and microtubule capture mechanisms. One of the earliest steps in the formation of a cortical platform center is the recruitment and activation of the Rho family of small GTPases. Downstream GTPase-activated effector proteins, including actin binding proteins and +TIPs, are then recruited to these activated sites. This sets off a molecular cascade of events that culminates in the polarization and polymerization of actin and the capturing of the growing ends of microtubules. The strength of the actin–microtubule connection is likely to have a marked impact on the length of time that microtubules are polarized at cortical platforms. In simpler eukaryotes where microtubule capture typically occurs over short periods of time, these linkages are indirect, involving multiple proteins, some with actin binding domains and others with microtubule or +TIP binding domains. In more complex eukaryotes with needs to prolong the capture process, spectraplakins evolved as scaffold proteins that can bind F-actin, +TIPs, microtubules, and likely a myriad of other proteins. These proteins are likely to function not only in stabilizing microtubule–actin interactions, but also in integrating other events, such as cell migration or cell–cell adhesion, that may take place at cortical platforms. See text for detailed descriptions of the proteins and structures shown here.
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fig1: Schematic view of cortical platform formation, maturation, and function. Cortical platforms are localized membrane-associated sites that develop into a rich molecular center for the convergence of transmembrane receptors, signal transduction proteins, actin polymerization machinery, and microtubule capture mechanisms. One of the earliest steps in the formation of a cortical platform center is the recruitment and activation of the Rho family of small GTPases. Downstream GTPase-activated effector proteins, including actin binding proteins and +TIPs, are then recruited to these activated sites. This sets off a molecular cascade of events that culminates in the polarization and polymerization of actin and the capturing of the growing ends of microtubules. The strength of the actin–microtubule connection is likely to have a marked impact on the length of time that microtubules are polarized at cortical platforms. In simpler eukaryotes where microtubule capture typically occurs over short periods of time, these linkages are indirect, involving multiple proteins, some with actin binding domains and others with microtubule or +TIP binding domains. In more complex eukaryotes with needs to prolong the capture process, spectraplakins evolved as scaffold proteins that can bind F-actin, +TIPs, microtubules, and likely a myriad of other proteins. These proteins are likely to function not only in stabilizing microtubule–actin interactions, but also in integrating other events, such as cell migration or cell–cell adhesion, that may take place at cortical platforms. See text for detailed descriptions of the proteins and structures shown here.

Mentions: Cells migrate by coordinating cytoskeletal-mediated extensions and contractions concomitantly with making and breaking contacts to an underlying substratum. To orchestrate directional movements, cells must activate a specific site(s) at the membrane periphery in response to a polarized external cue (Fig. 1; top left). A particular locale then becomes a “cortical platform” for the transmission of converging internal signals that are necessary to elicit subsequent cytoskeletal responses. The outcome is dependent upon the cell type and the precise signaling pathways that are engaged, and can range from the polymerization and/or reorganization of actin to the polarized capture and stabilization of microtubules and their associated microtubule organizing center (MTOC).


Coordinating cytoskeletal tracks to polarize cellular movements.

Kodama A, Lechler T, Fuchs E - J. Cell Biol. (2004)

Schematic view of cortical platform formation, maturation, and function. Cortical platforms are localized membrane-associated sites that develop into a rich molecular center for the convergence of transmembrane receptors, signal transduction proteins, actin polymerization machinery, and microtubule capture mechanisms. One of the earliest steps in the formation of a cortical platform center is the recruitment and activation of the Rho family of small GTPases. Downstream GTPase-activated effector proteins, including actin binding proteins and +TIPs, are then recruited to these activated sites. This sets off a molecular cascade of events that culminates in the polarization and polymerization of actin and the capturing of the growing ends of microtubules. The strength of the actin–microtubule connection is likely to have a marked impact on the length of time that microtubules are polarized at cortical platforms. In simpler eukaryotes where microtubule capture typically occurs over short periods of time, these linkages are indirect, involving multiple proteins, some with actin binding domains and others with microtubule or +TIP binding domains. In more complex eukaryotes with needs to prolong the capture process, spectraplakins evolved as scaffold proteins that can bind F-actin, +TIPs, microtubules, and likely a myriad of other proteins. These proteins are likely to function not only in stabilizing microtubule–actin interactions, but also in integrating other events, such as cell migration or cell–cell adhesion, that may take place at cortical platforms. See text for detailed descriptions of the proteins and structures shown here.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172533&req=5

fig1: Schematic view of cortical platform formation, maturation, and function. Cortical platforms are localized membrane-associated sites that develop into a rich molecular center for the convergence of transmembrane receptors, signal transduction proteins, actin polymerization machinery, and microtubule capture mechanisms. One of the earliest steps in the formation of a cortical platform center is the recruitment and activation of the Rho family of small GTPases. Downstream GTPase-activated effector proteins, including actin binding proteins and +TIPs, are then recruited to these activated sites. This sets off a molecular cascade of events that culminates in the polarization and polymerization of actin and the capturing of the growing ends of microtubules. The strength of the actin–microtubule connection is likely to have a marked impact on the length of time that microtubules are polarized at cortical platforms. In simpler eukaryotes where microtubule capture typically occurs over short periods of time, these linkages are indirect, involving multiple proteins, some with actin binding domains and others with microtubule or +TIP binding domains. In more complex eukaryotes with needs to prolong the capture process, spectraplakins evolved as scaffold proteins that can bind F-actin, +TIPs, microtubules, and likely a myriad of other proteins. These proteins are likely to function not only in stabilizing microtubule–actin interactions, but also in integrating other events, such as cell migration or cell–cell adhesion, that may take place at cortical platforms. See text for detailed descriptions of the proteins and structures shown here.
Mentions: Cells migrate by coordinating cytoskeletal-mediated extensions and contractions concomitantly with making and breaking contacts to an underlying substratum. To orchestrate directional movements, cells must activate a specific site(s) at the membrane periphery in response to a polarized external cue (Fig. 1; top left). A particular locale then becomes a “cortical platform” for the transmission of converging internal signals that are necessary to elicit subsequent cytoskeletal responses. The outcome is dependent upon the cell type and the precise signaling pathways that are engaged, and can range from the polymerization and/or reorganization of actin to the polarized capture and stabilization of microtubules and their associated microtubule organizing center (MTOC).

Bottom Line: For many years after the discovery of actin filaments and microtubules, it was widely assumed that their polymerization, organization, and functions were largely distinct.However, in recent years it has become increasingly apparent that coordinated interactions between microtubules and filamentous actin are involved in many polarized processes, including cell shape, mitotic spindle orientation, motility, growth cone guidance, and wound healing.In the past few years, significant strides have been made in unraveling the intricacies that govern these intertwined cytoskeletal rearrangements.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.

ABSTRACT
For many years after the discovery of actin filaments and microtubules, it was widely assumed that their polymerization, organization, and functions were largely distinct. However, in recent years it has become increasingly apparent that coordinated interactions between microtubules and filamentous actin are involved in many polarized processes, including cell shape, mitotic spindle orientation, motility, growth cone guidance, and wound healing. In the past few years, significant strides have been made in unraveling the intricacies that govern these intertwined cytoskeletal rearrangements.

Show MeSH
Related in: MedlinePlus