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GTRAP3-18 serves as a negative regulator of Rab1 in protein transport and neuronal differentiation.

Maier S, Reiterer V, Ruggiero AM, Rothstein JD, Thomas S, Dahm R, Sitte HH, Farhan H - J. Cell. Mol. Med. (2008)

Bottom Line: The effects on the early secretory pathway in HEK293 cells were: reduction of the rate of ER-to-Golgi transport of the vesicular stomatitis virus glycoprotein (VSVG), slowed accumulation of a Golgi marker plasmid in pre-Golgi structures after Brefeldin A treatment and inhibition of cargo concentration of the neuronal glutamate transporter excitatory amino-acid carrier 1 (EAAC1) into transpor complexes in HEK293 cells, an effect that could be completely reversed in the presence of an excess of Rab1.The inhibitory effect of GTRAP3-18 on neurite growth was rescued by co-expression with Rab1, supporting the conclusion that GTRAP 3-18 acted by inhibiting Rab1 action.Finally, we hypothesized that expression of GTRAP3-18 in the brain shoul be lower at stages of active synaptogenesis compared to early developmental stages.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmacology, Center for Biomolecular Medicine and Pharmacology, Medical University Vienna, Waehringer Strasse, Vienna, Austria.

ABSTRACT
Glutamate transporter associated protein 3-18 (GTRAP3-18) is an endoplasmic reticulum (ER)-localized protein belonging to the prenylated rab-acceptor-family interacting with small Rab GTPases, which regulate intracellular trafficking events. Its impact on secretory trafficking has not been investigated. We report here that GTRAP3-18 has an inhibitory effect on Rab1, which is involved in ER-to-Golg trafficking. The effects on the early secretory pathway in HEK293 cells were: reduction of the rate of ER-to-Golgi transport of the vesicular stomatitis virus glycoprotein (VSVG), slowed accumulation of a Golgi marker plasmid in pre-Golgi structures after Brefeldin A treatment and inhibition of cargo concentration of the neuronal glutamate transporter excitatory amino-acid carrier 1 (EAAC1) into transpor complexes in HEK293 cells, an effect that could be completely reversed in the presence of an excess of Rab1. In accordance with the known role of Rab1 in neurite formation, overexpression of GTRAP3-18 significantly inhibited the length of outgrowing neurites in differentiated CAD cells. The inhibitory effect of GTRAP3-18 on neurite growth was rescued by co-expression with Rab1, supporting the conclusion that GTRAP 3-18 acted by inhibiting Rab1 action. Finally, we hypothesized that expression of GTRAP3-18 in the brain shoul be lower at stages of active synaptogenesis compared to early developmental stages. This was the case as expression of GTRAP3-18 declined from E17 to P0 and adult rat brains. Thus, we propose a model where protein trafficking and neuronal differentiation are directly linked by the interaction of Rab1 and its regulator GTRAP3-18.

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Expression pattern of GTRAP3-18 during developmental stages that are relevant for neurite outgrowth and synaptogenesis. Total brain RNA of Sprague-Dawley rats of different developmental stages was isolated and subjected to GTRAP and GAPDH double semi-quantitative RT-PCR. A scatter plot shows all measured values for GTRAP3-18 expression after correction for GAPDH levels as arbitrary units (A.U.). The black line represents the mean per sample. P-values were calculated with an anova followed by Bonferroni's multiple comparison test.
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fig07: Expression pattern of GTRAP3-18 during developmental stages that are relevant for neurite outgrowth and synaptogenesis. Total brain RNA of Sprague-Dawley rats of different developmental stages was isolated and subjected to GTRAP and GAPDH double semi-quantitative RT-PCR. A scatter plot shows all measured values for GTRAP3-18 expression after correction for GAPDH levels as arbitrary units (A.U.). The black line represents the mean per sample. P-values were calculated with an anova followed by Bonferroni's multiple comparison test.

Mentions: In order to confirm that the expression of GTRAP3-18 shows a drop also in our case we tested the expression levels of GTRAP3-18 (by semi-quantitative RT-PCR) at specific developmental stages (embryonic day 17 [E17], the first post-natal day [P0] and in adult rats). We found that the expression of GTRAP3-18 showed a statistically significant decline from E17 to P0 and adult rat (Fig. 7).


GTRAP3-18 serves as a negative regulator of Rab1 in protein transport and neuronal differentiation.

Maier S, Reiterer V, Ruggiero AM, Rothstein JD, Thomas S, Dahm R, Sitte HH, Farhan H - J. Cell. Mol. Med. (2008)

Expression pattern of GTRAP3-18 during developmental stages that are relevant for neurite outgrowth and synaptogenesis. Total brain RNA of Sprague-Dawley rats of different developmental stages was isolated and subjected to GTRAP and GAPDH double semi-quantitative RT-PCR. A scatter plot shows all measured values for GTRAP3-18 expression after correction for GAPDH levels as arbitrary units (A.U.). The black line represents the mean per sample. P-values were calculated with an anova followed by Bonferroni's multiple comparison test.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3823040&req=5

fig07: Expression pattern of GTRAP3-18 during developmental stages that are relevant for neurite outgrowth and synaptogenesis. Total brain RNA of Sprague-Dawley rats of different developmental stages was isolated and subjected to GTRAP and GAPDH double semi-quantitative RT-PCR. A scatter plot shows all measured values for GTRAP3-18 expression after correction for GAPDH levels as arbitrary units (A.U.). The black line represents the mean per sample. P-values were calculated with an anova followed by Bonferroni's multiple comparison test.
Mentions: In order to confirm that the expression of GTRAP3-18 shows a drop also in our case we tested the expression levels of GTRAP3-18 (by semi-quantitative RT-PCR) at specific developmental stages (embryonic day 17 [E17], the first post-natal day [P0] and in adult rats). We found that the expression of GTRAP3-18 showed a statistically significant decline from E17 to P0 and adult rat (Fig. 7).

Bottom Line: The effects on the early secretory pathway in HEK293 cells were: reduction of the rate of ER-to-Golgi transport of the vesicular stomatitis virus glycoprotein (VSVG), slowed accumulation of a Golgi marker plasmid in pre-Golgi structures after Brefeldin A treatment and inhibition of cargo concentration of the neuronal glutamate transporter excitatory amino-acid carrier 1 (EAAC1) into transpor complexes in HEK293 cells, an effect that could be completely reversed in the presence of an excess of Rab1.The inhibitory effect of GTRAP3-18 on neurite growth was rescued by co-expression with Rab1, supporting the conclusion that GTRAP 3-18 acted by inhibiting Rab1 action.Finally, we hypothesized that expression of GTRAP3-18 in the brain shoul be lower at stages of active synaptogenesis compared to early developmental stages.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmacology, Center for Biomolecular Medicine and Pharmacology, Medical University Vienna, Waehringer Strasse, Vienna, Austria.

ABSTRACT
Glutamate transporter associated protein 3-18 (GTRAP3-18) is an endoplasmic reticulum (ER)-localized protein belonging to the prenylated rab-acceptor-family interacting with small Rab GTPases, which regulate intracellular trafficking events. Its impact on secretory trafficking has not been investigated. We report here that GTRAP3-18 has an inhibitory effect on Rab1, which is involved in ER-to-Golg trafficking. The effects on the early secretory pathway in HEK293 cells were: reduction of the rate of ER-to-Golgi transport of the vesicular stomatitis virus glycoprotein (VSVG), slowed accumulation of a Golgi marker plasmid in pre-Golgi structures after Brefeldin A treatment and inhibition of cargo concentration of the neuronal glutamate transporter excitatory amino-acid carrier 1 (EAAC1) into transpor complexes in HEK293 cells, an effect that could be completely reversed in the presence of an excess of Rab1. In accordance with the known role of Rab1 in neurite formation, overexpression of GTRAP3-18 significantly inhibited the length of outgrowing neurites in differentiated CAD cells. The inhibitory effect of GTRAP3-18 on neurite growth was rescued by co-expression with Rab1, supporting the conclusion that GTRAP 3-18 acted by inhibiting Rab1 action. Finally, we hypothesized that expression of GTRAP3-18 in the brain shoul be lower at stages of active synaptogenesis compared to early developmental stages. This was the case as expression of GTRAP3-18 declined from E17 to P0 and adult rat brains. Thus, we propose a model where protein trafficking and neuronal differentiation are directly linked by the interaction of Rab1 and its regulator GTRAP3-18.

Show MeSH
Related in: MedlinePlus