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Akt regulates glutamate receptor trafficking and postsynaptic membrane elaboration at the Drosophila neuromuscular junction.

Lee HG, Zhao N, Campion BK, Nguyen MM, Selleck SB - Dev Neurobiol (2013)

Bottom Line: The single Drosophila Akt family member, Akt1 selectively altered the postsynaptic targeting of one glutamate receptor subunit, GluRIIA, and was required for the expansion of a specialized postsynaptic membrane compartment, the subsynaptic reticulum (SSR).Several lines of evidence indicated that Akt1 influences SSR assembly by regulation of Gtaxin, a Drosophila t-SNARE protein (Gorczyca et al., 2007) in a manner independent of the mislocalization of GluRIIA.Our findings show that Akt1 governs two critical elements of synapse development, neurotransmitter receptor localization, and postsynaptic membrane elaboration.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802.

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The Akt signaling system and level of Akt1 knockdown using RNA interference in Drosophila. A: In this summary, kinases Rheb, and Tsc1/2 are purple symbols, phosphatases are green, and other components of TOR1 and TOR2 complex are blue. Akt1 is activated by growth factors via Pi3K and PDK1 and by nutritional sensing through Tsc1/2 and TOR complexes. Relationships that are not fully understood or have several possible intermediary steps are shown as dashed arrows or a question mark (adapted from Dimitroff et al., 2012). B: Akt1 function was compromised by muscle-specific expression of an Akt1RNAi construct using the GAL4-UAS system. The level of phosphorylated Akt1 was measured by Western blot. Total muscle proteins were prepared from third instar larval muscles of control animals (UAS-Akt1RNAi transgene only; UAS-Akt1RNAi/+) or Akt1RNAi animals with muscle specific knockdown of Akt1 using 24B-GAL4 driver (24B-GAL4>UAS-Akt1RNAi). Akt1 was dramatically decreased in muscle tissue expressing Akt1RNAi as compared with controls. Measures of β-Actin were used as a protein loading controls. Total proteins extracted from either one (1×) or two larvae (2×) were loaded.
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fig01: The Akt signaling system and level of Akt1 knockdown using RNA interference in Drosophila. A: In this summary, kinases Rheb, and Tsc1/2 are purple symbols, phosphatases are green, and other components of TOR1 and TOR2 complex are blue. Akt1 is activated by growth factors via Pi3K and PDK1 and by nutritional sensing through Tsc1/2 and TOR complexes. Relationships that are not fully understood or have several possible intermediary steps are shown as dashed arrows or a question mark (adapted from Dimitroff et al., 2012). B: Akt1 function was compromised by muscle-specific expression of an Akt1RNAi construct using the GAL4-UAS system. The level of phosphorylated Akt1 was measured by Western blot. Total muscle proteins were prepared from third instar larval muscles of control animals (UAS-Akt1RNAi transgene only; UAS-Akt1RNAi/+) or Akt1RNAi animals with muscle specific knockdown of Akt1 using 24B-GAL4 driver (24B-GAL4>UAS-Akt1RNAi). Akt1 was dramatically decreased in muscle tissue expressing Akt1RNAi as compared with controls. Measures of β-Actin were used as a protein loading controls. Total proteins extracted from either one (1×) or two larvae (2×) were loaded.

Mentions: Akt1 plays a central role in a number of signaling processes, acting both downstream and upstream of growth factor and target of rapamycin-directed events. The Akt1 kinase governs a number of cellular activities including cell proliferation, cell survival, and cytoskeleton organization [Fig. 1(A)]. Given these diverse and critical functions, we explored the role of Akt1 in synapse assembly. In addition to the well-described Akt1 mutant alleles (Staveley et al., 1998; Mozden and Rubin, 1999; Guo and Zhong, 2006), we used an Akt1RNAi transgene (Dietzl et al., 2007) to inhibit Akt1 function selectively in either motoneurons or muscle cells. To assess the level of inhibition achieved by the Akt1RNAi construct, we measured the level of phosphorylated Akt1 (active form of Akt1) by western blot. Using a muscle-directed GAL4 to drive the expression of UAS-Akt1RNAi, phosphorylated Akt1 protein was reduced to 24.2% of wild-type level in third instar larval muscle tissue [Fig. 1(B)].


Akt regulates glutamate receptor trafficking and postsynaptic membrane elaboration at the Drosophila neuromuscular junction.

Lee HG, Zhao N, Campion BK, Nguyen MM, Selleck SB - Dev Neurobiol (2013)

The Akt signaling system and level of Akt1 knockdown using RNA interference in Drosophila. A: In this summary, kinases Rheb, and Tsc1/2 are purple symbols, phosphatases are green, and other components of TOR1 and TOR2 complex are blue. Akt1 is activated by growth factors via Pi3K and PDK1 and by nutritional sensing through Tsc1/2 and TOR complexes. Relationships that are not fully understood or have several possible intermediary steps are shown as dashed arrows or a question mark (adapted from Dimitroff et al., 2012). B: Akt1 function was compromised by muscle-specific expression of an Akt1RNAi construct using the GAL4-UAS system. The level of phosphorylated Akt1 was measured by Western blot. Total muscle proteins were prepared from third instar larval muscles of control animals (UAS-Akt1RNAi transgene only; UAS-Akt1RNAi/+) or Akt1RNAi animals with muscle specific knockdown of Akt1 using 24B-GAL4 driver (24B-GAL4>UAS-Akt1RNAi). Akt1 was dramatically decreased in muscle tissue expressing Akt1RNAi as compared with controls. Measures of β-Actin were used as a protein loading controls. Total proteins extracted from either one (1×) or two larvae (2×) were loaded.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig01: The Akt signaling system and level of Akt1 knockdown using RNA interference in Drosophila. A: In this summary, kinases Rheb, and Tsc1/2 are purple symbols, phosphatases are green, and other components of TOR1 and TOR2 complex are blue. Akt1 is activated by growth factors via Pi3K and PDK1 and by nutritional sensing through Tsc1/2 and TOR complexes. Relationships that are not fully understood or have several possible intermediary steps are shown as dashed arrows or a question mark (adapted from Dimitroff et al., 2012). B: Akt1 function was compromised by muscle-specific expression of an Akt1RNAi construct using the GAL4-UAS system. The level of phosphorylated Akt1 was measured by Western blot. Total muscle proteins were prepared from third instar larval muscles of control animals (UAS-Akt1RNAi transgene only; UAS-Akt1RNAi/+) or Akt1RNAi animals with muscle specific knockdown of Akt1 using 24B-GAL4 driver (24B-GAL4>UAS-Akt1RNAi). Akt1 was dramatically decreased in muscle tissue expressing Akt1RNAi as compared with controls. Measures of β-Actin were used as a protein loading controls. Total proteins extracted from either one (1×) or two larvae (2×) were loaded.
Mentions: Akt1 plays a central role in a number of signaling processes, acting both downstream and upstream of growth factor and target of rapamycin-directed events. The Akt1 kinase governs a number of cellular activities including cell proliferation, cell survival, and cytoskeleton organization [Fig. 1(A)]. Given these diverse and critical functions, we explored the role of Akt1 in synapse assembly. In addition to the well-described Akt1 mutant alleles (Staveley et al., 1998; Mozden and Rubin, 1999; Guo and Zhong, 2006), we used an Akt1RNAi transgene (Dietzl et al., 2007) to inhibit Akt1 function selectively in either motoneurons or muscle cells. To assess the level of inhibition achieved by the Akt1RNAi construct, we measured the level of phosphorylated Akt1 (active form of Akt1) by western blot. Using a muscle-directed GAL4 to drive the expression of UAS-Akt1RNAi, phosphorylated Akt1 protein was reduced to 24.2% of wild-type level in third instar larval muscle tissue [Fig. 1(B)].

Bottom Line: The single Drosophila Akt family member, Akt1 selectively altered the postsynaptic targeting of one glutamate receptor subunit, GluRIIA, and was required for the expansion of a specialized postsynaptic membrane compartment, the subsynaptic reticulum (SSR).Several lines of evidence indicated that Akt1 influences SSR assembly by regulation of Gtaxin, a Drosophila t-SNARE protein (Gorczyca et al., 2007) in a manner independent of the mislocalization of GluRIIA.Our findings show that Akt1 governs two critical elements of synapse development, neurotransmitter receptor localization, and postsynaptic membrane elaboration.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802.

Show MeSH
Related in: MedlinePlus