Reference Report

Reference
Citation	Armbruster, K., Luschnig, S. (2012). The Drosophila Sec7 domain guanine nucleotide exchange factor protein Gartenzwerg localizes at the cis-Golgi and is essential for epithelial tube expansion. J. Cell Sci. 125(5): 1318--1328. (Export to RIS)
FlyBase ID	FBrf0218010
Publication Type	Research paper
PubMed ID	22349697
PubMed Abstract	Protein trafficking through the secretory pathway plays a key role in epithelial organ development and function. The expansion of tracheal tubes in Drosophila depends on trafficking of coatomer protein complex I (COPI)-coated vesicles between the Golgi complex and the endoplasmic reticulum (ER). However, it is not clear how this pathway is regulated. Here we describe an essential function of the Sec7 domain guanine nucleotide exchange factor (GEF) gartenzwerg (garz) in epithelial tube morphogenesis and protein secretion. garz is essential for the recruitment of COPI components and for normal Golgi organization. A GFP-Garz fusion protein is distributed in the cytoplasm and accumulates at the cis-Golgi. Localization to the Golgi requires the C-terminal part of Garz. Conversely, blocking the GDP-GTP nucleotide exchange reaction leads to constitutive Golgi localization, suggesting that Garz cycles in a GEF-activity-dependent manner between cytoplasmic and Golgi-membrane-localized pools. The related human ARF-GEF protein GBF1 can substitute for garz function in Drosophila tracheal cells, indicating that the relevant functions of these proteins are conserved. We show that garz interacts genetically with the ARF1 homolog ARF79F and with the ARF1-GAP homolog Gap69C, thus placing garz in a regulatory circuit that controls COPI trafficking in Drosophila. Interestingly, overexpression of garz causes accumulation of secreted proteins in the ER, suggesting that excessive garz activity leads to increased retrograde trafficking. Thus, garz might regulate epithelial tube morphogenesis and secretion by controlling the rate of trafficking of COPI vesicles.
DOI	10.1242/jcs.096263
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Language of Publication	English
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Publication Type	Journal
Abbreviation	J. Cell Sci.
Title	Journal of Cell Science
Publication Year	1966-
ISBN/ISSN	0021-9533
Data from Reference
Aberrations (1)
	Df(2R)Exel6061
Alleles (31)
	Arf79F^GD12522 Arf79F^{Scer\UAS.P\T.T:Avic\GFP-EGFP} Arf102F^GD4855 ArfGAP1^GD11259 ArfGAP1^KK102665 ArfGAP1^Scer\UAS.cRa Arl1^GD6768 Avic\GFP^{Scer\UAS.P\T.T:Hsap\Golgi} CG2219^GD9755 CG7039^GD10590 CG7735^GD15196 garz²³³ garz^{E740K.Scer\UAS.T:Avic\GFP-EGFP} garz^EP2028 garz^GD13940 garz^Q1427 garz^R1044 garz^Scer\UAS.B garz^{Scer\UAS.T:Avic\GFP-EGFP} garz^{W982.Scer\UAS.T:Avic\GFP-EGFP} garz^W982 garz^W1113 Hsap\GBF1^{E794K.Scer\UAS.T:Ivir\HA1} Hsap\GBF1^{Scer\UAS.T:Ivir\HA1} Rab4^{Scer\UAS.T:Disc\RFP} Scer\GAL4^69B Scer\GAL4^btl.PS Scer\GAL4^GMR.PF sec31^{Scer\UAS.T:Disc\RFP-mCherry} T:Avic\GFP^EGFP verm^{Scer\UAS.T:Disc\RFP-mRFP}
Constructs (23)
	M{UAS-garz.GFP} P{GAL4-btl.S} P{GAL4-ninaE.GMR} P{GD4855} P{GD6768} P{GD9755} P{GD10590} P{GD11259} P{GD12522} P{GD13940} P{GD15196} P{KK102665} P{UAS-Arf79F.GFP} P{UAS-Gap69C.R} P{UAS-garz.GFP.E740K} P{UAS-garz.GFP.W982} P{UAS-garz.PB} P{UAS-GBF1.HA.E794K} P{UAS-GBF1.HA} P{UASp-GFP.Golgi} P{UAS-Rab4-mRFP} P{UAS-sec31.RFP} P{UAS-verm.RFP}
Genes (24)
	Arf79F Arf102F ArfGAP1 Arl1 Avic\GFP CG2219 CG7039 CG7735 crb Fas3 garz Glg1 GM130 Gmap Hsap\GBF1 pio Rab4 Sas Scer\GAL4 sec31 serp T:Ivir\HA1 verm β'Cop
Insertions (2)
	P{EP}garz^EP2028 P{GawB}69B
Natural transposons (2)
	Dmau\mariner P-element