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Light-regulated interaction of Dmoesin with TRP and TRPL channels is required for maintenance of photoreceptors.

Chorna-Ornan I, Tzarfaty V, Ankri-Eliahoo G, Joel-Almagor T, Meyer NE, Huber A, Payre F, Minke B - J. Cell Biol. (2005)

Bottom Line: Furthermore, we show that light-activated migration of Dmoesin results from the dephosphorylation of a conserved threonine in Dmoesin.The expression of a Dmoesin mutant form that impairs this phosphorylation inhibits Dmoesin movement and leads to light-induced retinal degeneration.Thus, our data strongly suggest that the light- and phosphorylation-dependent dynamic association of Dmoesin to membrane channels is involved in maintenance of the photoreceptor cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.

ABSTRACT
Recent studies in Drosophila melanogaster retina indicate that absorption of light causes the translocation of signaling molecules and actin from the photoreceptor's signaling membrane to the cytosol, but the underlying mechanisms are not fully understood. As ezrin-radixin-moesin (ERM) proteins are known to regulate actin-membrane interactions in a signal-dependent manner, we analyzed the role of Dmoesin, the unique D. melanogaster ERM, in response to light. We report that the illumination of dark-raised flies triggers the dissociation of Dmoesin from the light-sensitive transient receptor potential (TRP) and TRP-like channels, followed by the migration of Dmoesin from the membrane to the cytoplasm. Furthermore, we show that light-activated migration of Dmoesin results from the dephosphorylation of a conserved threonine in Dmoesin. The expression of a Dmoesin mutant form that impairs this phosphorylation inhibits Dmoesin movement and leads to light-induced retinal degeneration. Thus, our data strongly suggest that the light- and phosphorylation-dependent dynamic association of Dmoesin to membrane channels is involved in maintenance of the photoreceptor cells.

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Related in: MedlinePlus

A scheme that summarizes the subcellular organization of Dmoesin and the major signaling proteins in the rhabdomeric membrane. TRP anchors the INAD signaling complex, which includes PLC and eyePKC (ePKC), to the plasma membrane via the PDZ3 domain of INAD. The NH2-terminal region of Dmoesin molecules (arrowheads) bind either directly or through a PDZ adaptor protein to the TRP and TRPL channels, whereas the COOH-terminal region is bound to the actin cytoskeleton. The phosphorylated site of T559 is indicated by an asterisk.
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fig10: A scheme that summarizes the subcellular organization of Dmoesin and the major signaling proteins in the rhabdomeric membrane. TRP anchors the INAD signaling complex, which includes PLC and eyePKC (ePKC), to the plasma membrane via the PDZ3 domain of INAD. The NH2-terminal region of Dmoesin molecules (arrowheads) bind either directly or through a PDZ adaptor protein to the TRP and TRPL channels, whereas the COOH-terminal region is bound to the actin cytoskeleton. The phosphorylated site of T559 is indicated by an asterisk.

Mentions: In this study, the critical role of T559 phosphorylation on Dmoesin activation (Polesello et al., 2002; Speck et al., 2003) was extended through the demonstration that dissociation of the Dmoesin from the channel proteins upon illumination depends on T559 dephosphorylation. Accordingly, specific antibodies for the phosphorylated T559 form of Dmoesin immunoprecipitated the TRP channel of dark-raised flies, but not of illuminated flies. Moreover, monospecific TRP antibody immunoprecipitated the phosphorylated form of Dmoesin only in dark-raised flies. These results strongly suggest that only the phosphorylated form of Dmoesin binds TRP (Fig. 10). This finding further suggests that light induces dephosphorylation of Dmoesin, leading to dissociation of Dmoesin from the channel proteins, followed by its movement to the cell body.


Light-regulated interaction of Dmoesin with TRP and TRPL channels is required for maintenance of photoreceptors.

Chorna-Ornan I, Tzarfaty V, Ankri-Eliahoo G, Joel-Almagor T, Meyer NE, Huber A, Payre F, Minke B - J. Cell Biol. (2005)

A scheme that summarizes the subcellular organization of Dmoesin and the major signaling proteins in the rhabdomeric membrane. TRP anchors the INAD signaling complex, which includes PLC and eyePKC (ePKC), to the plasma membrane via the PDZ3 domain of INAD. The NH2-terminal region of Dmoesin molecules (arrowheads) bind either directly or through a PDZ adaptor protein to the TRP and TRPL channels, whereas the COOH-terminal region is bound to the actin cytoskeleton. The phosphorylated site of T559 is indicated by an asterisk.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1936436&req=5

fig10: A scheme that summarizes the subcellular organization of Dmoesin and the major signaling proteins in the rhabdomeric membrane. TRP anchors the INAD signaling complex, which includes PLC and eyePKC (ePKC), to the plasma membrane via the PDZ3 domain of INAD. The NH2-terminal region of Dmoesin molecules (arrowheads) bind either directly or through a PDZ adaptor protein to the TRP and TRPL channels, whereas the COOH-terminal region is bound to the actin cytoskeleton. The phosphorylated site of T559 is indicated by an asterisk.
Mentions: In this study, the critical role of T559 phosphorylation on Dmoesin activation (Polesello et al., 2002; Speck et al., 2003) was extended through the demonstration that dissociation of the Dmoesin from the channel proteins upon illumination depends on T559 dephosphorylation. Accordingly, specific antibodies for the phosphorylated T559 form of Dmoesin immunoprecipitated the TRP channel of dark-raised flies, but not of illuminated flies. Moreover, monospecific TRP antibody immunoprecipitated the phosphorylated form of Dmoesin only in dark-raised flies. These results strongly suggest that only the phosphorylated form of Dmoesin binds TRP (Fig. 10). This finding further suggests that light induces dephosphorylation of Dmoesin, leading to dissociation of Dmoesin from the channel proteins, followed by its movement to the cell body.

Bottom Line: Furthermore, we show that light-activated migration of Dmoesin results from the dephosphorylation of a conserved threonine in Dmoesin.The expression of a Dmoesin mutant form that impairs this phosphorylation inhibits Dmoesin movement and leads to light-induced retinal degeneration.Thus, our data strongly suggest that the light- and phosphorylation-dependent dynamic association of Dmoesin to membrane channels is involved in maintenance of the photoreceptor cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.

ABSTRACT
Recent studies in Drosophila melanogaster retina indicate that absorption of light causes the translocation of signaling molecules and actin from the photoreceptor's signaling membrane to the cytosol, but the underlying mechanisms are not fully understood. As ezrin-radixin-moesin (ERM) proteins are known to regulate actin-membrane interactions in a signal-dependent manner, we analyzed the role of Dmoesin, the unique D. melanogaster ERM, in response to light. We report that the illumination of dark-raised flies triggers the dissociation of Dmoesin from the light-sensitive transient receptor potential (TRP) and TRP-like channels, followed by the migration of Dmoesin from the membrane to the cytoplasm. Furthermore, we show that light-activated migration of Dmoesin results from the dephosphorylation of a conserved threonine in Dmoesin. The expression of a Dmoesin mutant form that impairs this phosphorylation inhibits Dmoesin movement and leads to light-induced retinal degeneration. Thus, our data strongly suggest that the light- and phosphorylation-dependent dynamic association of Dmoesin to membrane channels is involved in maintenance of the photoreceptor cells.

Show MeSH
Related in: MedlinePlus