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Local ERM activation and dynamic growth cones at Schwann cell tips implicated in efficient formation of nodes of Ranvier.

Gatto CL, Walker BJ, Lambert S - J. Cell Biol. (2003)

Bottom Line: In the peripheral nervous system, axo-glial cell contacts have been implicated in Schwann cell (SC) differentiation and formation of the nodes of Ranvier.SC microvilli establish axonal contact at mature nodes, and their components have been observed to localize early to sites of developing nodes.However, a role for these contacts in node formation remains controversial.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Program in Neuroscience, University of Massachusetts Medical School, 4 Biotech, 377 Plantation St., Suite 326, Worcester, MA 01605, USA.

ABSTRACT
Nodes of Ranvier are specialized, highly polarized axonal domains crucial to the propagation of saltatory action potentials. In the peripheral nervous system, axo-glial cell contacts have been implicated in Schwann cell (SC) differentiation and formation of the nodes of Ranvier. SC microvilli establish axonal contact at mature nodes, and their components have been observed to localize early to sites of developing nodes. However, a role for these contacts in node formation remains controversial. Using a myelinating explant culture system, we have observed that SCs reorganize and polarize microvillar components, such as the ezrin-binding phosphoprotein 50 kD/regulatory cofactor of the sodium-hydrogen exchanger isoform 3 (NHERF-1), actin, and the activated ezrin, radixin, and moesin family proteins before myelination in response to inductive signals. These components are targeted to the SC distal tips where live cell imaging reveals novel, dynamic growth cone-like behavior. Furthermore, localized activation of the Rho signaling pathway at SC tips gives rise to these microvillar component-enriched "caps" and influences the efficiency of node formation.

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SC tips display novel growth cone–like behavior. Isolated SCs were studied using time-lapse live cell imaging. (A, arrow) SC tips displayed dynamic, active remodeling similar to that seen in an axonal growth cone (B–M). Specifically, (E and F) filopodial extensions and (G–M) lamellipodial elaborations were evident. Bars, 10 μm.
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fig5: SC tips display novel growth cone–like behavior. Isolated SCs were studied using time-lapse live cell imaging. (A, arrow) SC tips displayed dynamic, active remodeling similar to that seen in an axonal growth cone (B–M). Specifically, (E and F) filopodial extensions and (G–M) lamellipodial elaborations were evident. Bars, 10 μm.

Mentions: As explant studies demonstrated the specific rearrangement of EBP50 at SC tips, isolated SCs were imaged to examine the general nature of the cells' distal region. SC tips were reminiscent of actively remodeling axonal growth cones. Isolated cells revealed significant detail including the elaboration of lamellipodia and extension of filopodia (Fig. 5). We hypothesize that these SC distal tips may serve as novel glial growth cone–type structures that enable axonal recognition and segregation, as well as the establishment of early nodes in the process of myelination.


Local ERM activation and dynamic growth cones at Schwann cell tips implicated in efficient formation of nodes of Ranvier.

Gatto CL, Walker BJ, Lambert S - J. Cell Biol. (2003)

SC tips display novel growth cone–like behavior. Isolated SCs were studied using time-lapse live cell imaging. (A, arrow) SC tips displayed dynamic, active remodeling similar to that seen in an axonal growth cone (B–M). Specifically, (E and F) filopodial extensions and (G–M) lamellipodial elaborations were evident. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172691&req=5

fig5: SC tips display novel growth cone–like behavior. Isolated SCs were studied using time-lapse live cell imaging. (A, arrow) SC tips displayed dynamic, active remodeling similar to that seen in an axonal growth cone (B–M). Specifically, (E and F) filopodial extensions and (G–M) lamellipodial elaborations were evident. Bars, 10 μm.
Mentions: As explant studies demonstrated the specific rearrangement of EBP50 at SC tips, isolated SCs were imaged to examine the general nature of the cells' distal region. SC tips were reminiscent of actively remodeling axonal growth cones. Isolated cells revealed significant detail including the elaboration of lamellipodia and extension of filopodia (Fig. 5). We hypothesize that these SC distal tips may serve as novel glial growth cone–type structures that enable axonal recognition and segregation, as well as the establishment of early nodes in the process of myelination.

Bottom Line: In the peripheral nervous system, axo-glial cell contacts have been implicated in Schwann cell (SC) differentiation and formation of the nodes of Ranvier.SC microvilli establish axonal contact at mature nodes, and their components have been observed to localize early to sites of developing nodes.However, a role for these contacts in node formation remains controversial.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Program in Neuroscience, University of Massachusetts Medical School, 4 Biotech, 377 Plantation St., Suite 326, Worcester, MA 01605, USA.

ABSTRACT
Nodes of Ranvier are specialized, highly polarized axonal domains crucial to the propagation of saltatory action potentials. In the peripheral nervous system, axo-glial cell contacts have been implicated in Schwann cell (SC) differentiation and formation of the nodes of Ranvier. SC microvilli establish axonal contact at mature nodes, and their components have been observed to localize early to sites of developing nodes. However, a role for these contacts in node formation remains controversial. Using a myelinating explant culture system, we have observed that SCs reorganize and polarize microvillar components, such as the ezrin-binding phosphoprotein 50 kD/regulatory cofactor of the sodium-hydrogen exchanger isoform 3 (NHERF-1), actin, and the activated ezrin, radixin, and moesin family proteins before myelination in response to inductive signals. These components are targeted to the SC distal tips where live cell imaging reveals novel, dynamic growth cone-like behavior. Furthermore, localized activation of the Rho signaling pathway at SC tips gives rise to these microvillar component-enriched "caps" and influences the efficiency of node formation.

Show MeSH
Related in: MedlinePlus