The requirement of DAG (diacylglycerol) to recruit PKD (protein kinase D) to the TGN (trans-Golgi network) for the targeting of transport carriers to the cell surface, has led us to a search for new components involved in this regulatory pathway. Previous findings reveal that the heterotrimeric Gβγ (GTP-binding protein βγ subunits) act as PKD activators, leading to fission of transport vesicles at the TGN. We have recently shown that PKCη (protein kinase Cη) functions as an intermediate member in the vesicle generating pathway. DAG is capable of activating this kinase at the TGN, and at the same time is able to recruit PKD to this organelle in order to interact with PKCη, allowing phosphorylation of PKD's activation loop. The most qualified candidates for the production of DAG at the TGN are PI-PLCs (phosphatidylinositol-specific phospholipases C), since some members of this family can be directly activated by Gβγ, utilizing PtdIns(4,5)P2 as a substrate, to produce the second messengers DAG and InsP3. In the present study we show that βγ-dependent Golgi fragmentation, PKD1 activation and TGN to plasma membrane transport were affected by a specific PI-PLC inhibitor, U73122 [1-(6-{[17-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione]. In addition, a recently described PI-PLC activator, m-3M3FBS [2,4,6-trimethyl-N-(m-3-trifluoromethylphenyl)benzenesulfonamide], induced vesiculation of the Golgi apparatus as well as PKD1 phosphorylation at its activation loop. Finally, using siRNA (small interfering RNA) to block several PI-PLCs, we were able to identify PLCβ3 as the sole member of this family involved in the regulation of the formation of transport carriers at the TGN. In conclusion, we demonstrate that fission of transport carriers at the TGN is dependent on PI-PLCs, specifically PLCβ3, which is necessary to activate PKCη and PKD in that Golgi compartment, via DAG production.
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Research Article|
July 26 2007
Phospholipase C β3 is a key component in the Gβγ/PKCη/PKD-mediated regulation of trans-Golgi network to plasma membrane transport
Alberto M. Díaz Añel
Alberto M. Díaz Añel
1
*Center for Molecular Genetics, University of California at San Diego, San Diego, CA, U.S.A.
†Laboratory of Neurobiology, INIMEC (Instituto de Investigación Médica ‘Mercedes y Martín Ferreyra’), Friuli 2434, Barrio Parque Vélez Sarsfield, 5016 Córdoba, Provincia de Córdoba, Argentina
1email adiazanel@immf.uncor.edu
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Publisher: Portland Press Ltd
Received:
March 14 2007
Accepted:
May 10 2007
Accepted Manuscript online:
May 10 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2007 Biochemical Society
2007
Biochem J (2007) 406 (1): 157–165.
Article history
Received:
March 14 2007
Accepted:
May 10 2007
Accepted Manuscript online:
May 10 2007
Citation
Alberto M. Díaz Añel; Phospholipase C β3 is a key component in the Gβγ/PKCη/PKD-mediated regulation of trans-Golgi network to plasma membrane transport. Biochem J 15 August 2007; 406 (1): 157–165. doi: https://doi.org/10.1042/BJ20070359
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