Limits...
Astrocytic αVβ3 integrin inhibits neurite outgrowth and promotes retraction of neuronal processes by clustering Thy-1.

Herrera-Molina R, Frischknecht R, Maldonado H, Seidenbecher CI, Gundelfinger ED, Hetz C, Aylwin Mde L, Schneider P, Quest AF, Leyton L - PLoS ONE (2012)

Bottom Line: In differentiating primary neurons exposed to α(V)β(3)-Fc, fewer and shorter dendrites were detected.This effect was abolished by cleavage of Thy-1 from the neuronal surface using phosphoinositide-specific phospholipase C (PI-PLC).Moreover, α(V)β(3)-Fc-induced Thy-1 clustering correlated in time and space with redistribution and inactivation of Src kinase.

View Article: PubMed Central - PubMed

Affiliation: Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.

ABSTRACT
Thy-1 is a membrane glycoprotein suggested to stabilize or inhibit growth of neuronal processes. However, its precise function has remained obscure, because its endogenous ligand is unknown. We previously showed that Thy-1 binds directly to α(V)β(3) integrin in trans eliciting responses in astrocytes. Nonetheless, whether α(V)β(3) integrin might also serve as a Thy-1-ligand triggering a neuronal response has not been explored. Thus, utilizing primary neurons and a neuron-derived cell line CAD, Thy-1-mediated effects of α(V)β(3) integrin on growth and retraction of neuronal processes were tested. In astrocyte-neuron co-cultures, endogenous α(V)β(3) integrin restricted neurite outgrowth. Likewise, α(V)β(3)-Fc was sufficient to suppress neurite extension in Thy-1(+), but not in Thy-1(-) CAD cells. In differentiating primary neurons exposed to α(V)β(3)-Fc, fewer and shorter dendrites were detected. This effect was abolished by cleavage of Thy-1 from the neuronal surface using phosphoinositide-specific phospholipase C (PI-PLC). Moreover, α(V)β(3)-Fc also induced retraction of already extended Thy-1(+)-axon-like neurites in differentiated CAD cells as well as of axonal terminals in differentiated primary neurons. Axonal retraction occurred when redistribution and clustering of Thy-1 molecules in the plasma membrane was induced by α(V)β(3) integrin. Binding of α(V)β(3)-Fc was detected in Thy-1 clusters during axon retraction of primary neurons. Moreover, α(V)β(3)-Fc-induced Thy-1 clustering correlated in time and space with redistribution and inactivation of Src kinase. Thus, our data indicates that α(V)β(3) integrin is a ligand for Thy-1 that upon binding not only restricts the growth of neurites, but also induces retraction of already existing processes by inducing Thy-1 clustering. We propose that these events participate in bi-directional astrocyte-neuron communication relevant to axonal repair after neuronal damage.

Show MeSH

Related in: MedlinePlus

Time course of process retraction induced by recombinant αVβ3-Fc.CAD cells were plated and differentiation was induced as indicated in Fig. 4A for 72 hours. Differentiated CAD cells were exposed to (A) supernatants depleted of recombinant αVβ3-Fc (Control) or (B) supernatants containing αVβ3-Fc for 75 minutes (αVβ3-Fc). Cell morphology was continuously monitored using a digital camera coupled to a microscope with a water-immersion objective and DIC optics. Images captured every 2.5 minutes are shown. White arrowheads indicate the position of the tip of the neurite at time point zero, whereas the black arrowhead shows the end of the trajectory after 75 minutes in (A) or after 12.5, 27.5, 42.5, 57.5 and 75 minutes in (B). A representative result of 5 independent retraction experiments is shown.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3316703&req=5

pone-0034295-g005: Time course of process retraction induced by recombinant αVβ3-Fc.CAD cells were plated and differentiation was induced as indicated in Fig. 4A for 72 hours. Differentiated CAD cells were exposed to (A) supernatants depleted of recombinant αVβ3-Fc (Control) or (B) supernatants containing αVβ3-Fc for 75 minutes (αVβ3-Fc). Cell morphology was continuously monitored using a digital camera coupled to a microscope with a water-immersion objective and DIC optics. Images captured every 2.5 minutes are shown. White arrowheads indicate the position of the tip of the neurite at time point zero, whereas the black arrowhead shows the end of the trajectory after 75 minutes in (A) or after 12.5, 27.5, 42.5, 57.5 and 75 minutes in (B). A representative result of 5 independent retraction experiments is shown.

Mentions: Additionally, terminal collapse preceded rapid neurite retraction, as observed using DIC optic-coupled live cell monitoring photographed during 75 minutes. In control differentiated CAD cells, neurites did not retract during these 75 minutes (Fig. 5A), whereas those exposed to αVβ3-Fc showed fast and steady retraction (Fig. 5B). The speed of neurite retraction, estimated as indicated in Materials and Methods, was −0.48±0.13 µm/minutes in αVβ3-Fc-treated CAD cells. To the contrary, those in control condition grew at a speed of 0.02±0.03 µm/minutes. Therefore, αVβ3-Fc not only induces Thy-1-dependent suppression of neurite outgrowth in CAD cells induced to differentiate, but also triggers redistribution of Thy-1 and axon-like neurite retraction in already differentiated CAD cells.


Astrocytic αVβ3 integrin inhibits neurite outgrowth and promotes retraction of neuronal processes by clustering Thy-1.

Herrera-Molina R, Frischknecht R, Maldonado H, Seidenbecher CI, Gundelfinger ED, Hetz C, Aylwin Mde L, Schneider P, Quest AF, Leyton L - PLoS ONE (2012)

Time course of process retraction induced by recombinant αVβ3-Fc.CAD cells were plated and differentiation was induced as indicated in Fig. 4A for 72 hours. Differentiated CAD cells were exposed to (A) supernatants depleted of recombinant αVβ3-Fc (Control) or (B) supernatants containing αVβ3-Fc for 75 minutes (αVβ3-Fc). Cell morphology was continuously monitored using a digital camera coupled to a microscope with a water-immersion objective and DIC optics. Images captured every 2.5 minutes are shown. White arrowheads indicate the position of the tip of the neurite at time point zero, whereas the black arrowhead shows the end of the trajectory after 75 minutes in (A) or after 12.5, 27.5, 42.5, 57.5 and 75 minutes in (B). A representative result of 5 independent retraction experiments is shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316703&req=5

pone-0034295-g005: Time course of process retraction induced by recombinant αVβ3-Fc.CAD cells were plated and differentiation was induced as indicated in Fig. 4A for 72 hours. Differentiated CAD cells were exposed to (A) supernatants depleted of recombinant αVβ3-Fc (Control) or (B) supernatants containing αVβ3-Fc for 75 minutes (αVβ3-Fc). Cell morphology was continuously monitored using a digital camera coupled to a microscope with a water-immersion objective and DIC optics. Images captured every 2.5 minutes are shown. White arrowheads indicate the position of the tip of the neurite at time point zero, whereas the black arrowhead shows the end of the trajectory after 75 minutes in (A) or after 12.5, 27.5, 42.5, 57.5 and 75 minutes in (B). A representative result of 5 independent retraction experiments is shown.
Mentions: Additionally, terminal collapse preceded rapid neurite retraction, as observed using DIC optic-coupled live cell monitoring photographed during 75 minutes. In control differentiated CAD cells, neurites did not retract during these 75 minutes (Fig. 5A), whereas those exposed to αVβ3-Fc showed fast and steady retraction (Fig. 5B). The speed of neurite retraction, estimated as indicated in Materials and Methods, was −0.48±0.13 µm/minutes in αVβ3-Fc-treated CAD cells. To the contrary, those in control condition grew at a speed of 0.02±0.03 µm/minutes. Therefore, αVβ3-Fc not only induces Thy-1-dependent suppression of neurite outgrowth in CAD cells induced to differentiate, but also triggers redistribution of Thy-1 and axon-like neurite retraction in already differentiated CAD cells.

Bottom Line: In differentiating primary neurons exposed to α(V)β(3)-Fc, fewer and shorter dendrites were detected.This effect was abolished by cleavage of Thy-1 from the neuronal surface using phosphoinositide-specific phospholipase C (PI-PLC).Moreover, α(V)β(3)-Fc-induced Thy-1 clustering correlated in time and space with redistribution and inactivation of Src kinase.

View Article: PubMed Central - PubMed

Affiliation: Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.

ABSTRACT
Thy-1 is a membrane glycoprotein suggested to stabilize or inhibit growth of neuronal processes. However, its precise function has remained obscure, because its endogenous ligand is unknown. We previously showed that Thy-1 binds directly to α(V)β(3) integrin in trans eliciting responses in astrocytes. Nonetheless, whether α(V)β(3) integrin might also serve as a Thy-1-ligand triggering a neuronal response has not been explored. Thus, utilizing primary neurons and a neuron-derived cell line CAD, Thy-1-mediated effects of α(V)β(3) integrin on growth and retraction of neuronal processes were tested. In astrocyte-neuron co-cultures, endogenous α(V)β(3) integrin restricted neurite outgrowth. Likewise, α(V)β(3)-Fc was sufficient to suppress neurite extension in Thy-1(+), but not in Thy-1(-) CAD cells. In differentiating primary neurons exposed to α(V)β(3)-Fc, fewer and shorter dendrites were detected. This effect was abolished by cleavage of Thy-1 from the neuronal surface using phosphoinositide-specific phospholipase C (PI-PLC). Moreover, α(V)β(3)-Fc also induced retraction of already extended Thy-1(+)-axon-like neurites in differentiated CAD cells as well as of axonal terminals in differentiated primary neurons. Axonal retraction occurred when redistribution and clustering of Thy-1 molecules in the plasma membrane was induced by α(V)β(3) integrin. Binding of α(V)β(3)-Fc was detected in Thy-1 clusters during axon retraction of primary neurons. Moreover, α(V)β(3)-Fc-induced Thy-1 clustering correlated in time and space with redistribution and inactivation of Src kinase. Thus, our data indicates that α(V)β(3) integrin is a ligand for Thy-1 that upon binding not only restricts the growth of neurites, but also induces retraction of already existing processes by inducing Thy-1 clustering. We propose that these events participate in bi-directional astrocyte-neuron communication relevant to axonal repair after neuronal damage.

Show MeSH
Related in: MedlinePlus