48 68

Cited 74 times in

The mammalian Sec6/8 complex interacts with Ca2+ signaling complexes and regulates their activity

Authors
 Dong Min Shin  ;  Xiao-Song Zhao  ;  Weizhong Zeng  ;  Marina Mozhayeva  ;  Shmuel Muallem 
Citation
 Journal of Cell Biology, Vol.150(5) : 1101-1112, 2000 
Journal Title
 Journal of Cell Biology 
ISSN
 0021-9525 
Issue Date
2000
MeSH
Actins/physiology ; Animals ; Brefeldin A/pharmacology ; Calcium/metabolism* ; Calcium Channels/isolation & purification ; Calcium Channels/physiology ; Calcium Signaling/drug effects ; Calcium Signaling/physiology* ; Carbachol/pharmacology ; Carrier Proteins/analysis ; Carrier Proteins/metabolism* ; Cell Membrane/physiology ; Cell Membrane/ultrastructure ; Cell Polarity ; Cells, Cultured ; Cytoskeleton/physiology ; Cytoskeleton/ultrastructure ; GTP-Binding Proteins/isolation & purification ; GTP-Binding Proteins/metabolism ; Golgi Apparatus/physiology ; Golgi Apparatus/ultrastructure ; Inositol 1,4,5-Trisphosphate Receptors ; Inositol Phosphates/pharmacology ; Membrane Potentials/drug effects ; Membrane Potentials/physiology ; Pancreas/cytology* ; Pancreas/physiology* ; Patch-Clamp Techniques ; Rats ; Receptors ; Cytoplasmic and Nuclear/isolation & purification ; Receptors ; Cytoplasmic and Nuclear/physiology
Keywords
Sec6/8 complex ; Ca2+ signaling proteins ; assembly ; actin cytoskeleton ; Ca2+ signaling
Abstract
The localization of various Ca(2+) transport and signaling proteins in secretory cells is highly restricted, resulting in polarized agonist-stimulated Ca(2+) waves. In the present work, we examined the possible roles of the Sec6/8 complex or the exocyst in polarized Ca(2+) signaling in pancreatic acinar cells. Immunolocalization by confocal microscopy showed that the Sec6/8 complex is excluded from tight junctions and secretory granules in these cells. The Sec6/8 complex was found in at least two cellular compartments, part of the complex showed similar, but not identical, localization with the Golgi apparatus and part of the complex associated with Ca(2+) signaling proteins next to the plasma membrane at the apical pole. Accordingly, immunoprecipitation (IP) of Sec8 did not coimmunoprecipitate betaCOP, Golgi 58K protein, or mannosidase II, all Golgi-resident proteins. By contrast, IP of Sec8 coimmunoprecipitates Sec6, type 3 inositol 1,4,5-trisphosphate receptors (IP(3)R3), and the Gbetagamma subunit of G proteins from pancreatic acinar cell extracts. Furthermore, the anti-Sec8 antibodies coimmunoprecipitate actin, Sec6, the plasma membrane Ca(2+) pump, the G protein subunits Galphaq and Gbetagamma, the beta1 isoform of phospholipase C, and the ER resident IP(3)R1 from brain microsomal extracts. Antibodies against the various signaling and Ca(2+) transport proteins coimmunoprecipitate Sec8 and the other signaling proteins. Dissociation of actin filaments in the immunoprecipitate had no effect on the interaction between Sec6 and Sec8, but released the actin and dissociated the interaction between the Sec6/8 complex and Ca(2+) signaling proteins. Hence, the interaction between the Sec6/8 and Ca(2+) signaling complexes is likely mediated by the actin cytoskeleton. The anti-Sec6 and anti-Sec8 antibodies inhibited Ca(2+) signaling at a step upstream of Ca(2+) release by IP(3). Disruption of the actin cytoskeleton with latrunculin B in intact cells resulted in partial translocation of Sec6 and Sec8 from membranes to the cytosol and interfered with propagation of agonist-evoked Ca(2+) waves. Our results suggest that the Sec6/8 complex has multiple roles in secretory cells including governing the polarized expression of Ca(2+) signaling complexes and regulation of their activity.
Files in This Item:
T200003408.pdf Download
DOI
10.1083/jcb.150.5.1101
Appears in Collections:
2. College of Dentistry (치과대학) > Dept. of Oral Biology (구강생물학교실) > 1. Journal Papers
Yonsei Authors
Shin, Dong Min(신동민) ORCID logo https://orcid.org/0000-0001-6042-0435
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/171682
사서에게 알리기
  feedback

qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse

Links