PMID- 23346930
OWN - NLM
STAT- MEDLINE
DCOM- 20130815
LR  - 20131121
IS  - 1600-0854 (Electronic)
IS  - 1398-9219 (Linking)
VI  - 14
IP  - 4
DP  - 2013 Apr
TI  - RalA GTPase tethers insulin granules to L- and R-type calcium channels through 
      binding alpha2 delta-1 subunit.
PG  - 428-39
LID - 10.1111/tra.12047 [doi]
AB  - RalA GTPase has been implicated in the regulated delivery of exocytotic vesicles 
      to the plasma membrane (PM) in mammalian cells. We had reported that RalA 
      regulates biphasic insulin secretion, which we have now determined to be 
      contributed by RalA direct interaction with voltage-gated calcium (Cav ) 
      channels. RalA knockdown (KD) in INS-1 cells and primary rat beta-cells resulted in 
      a reduction in Ca(2+) currents arising specifically from L-(Cav 1.2 and Cav 1.3) 
      and R-type (Cav 2.3) Ca(2+) channels. Restoration of RalA expression in RalA KD 
      cells rescued these defects in Ca(2+) currents. RalA co-immunoprecipitated with 
      the Cav alpha2 delta-1 auxiliary subunit known to bind the three Cav s. Moreover, the 
      functional molecular interactions between Cav alpha2 delta-1 and RalA on the PM shown by 
      total internal reflection fluorescent microscopy/FRET analysis could be induced 
      by glucose stimulation. KD of RalA inhibited trafficking of alpha2 delta-1 to insulin 
      granules without affecting the localization of the other Cav subunits. 
      Furthermore, we confirmed that RalA and alpha2 delta-1 functionally interact since RalA 
      KD-induced inhibition of Cav currents could not be recovered by RalA when alpha2 delta-1 
      was simultaneously knocked down. These data provide a mechanism for RalA function 
      in insulin secretion, whereby RalA binds alpha2 delta-1 on insulin granules to tether 
      these granules to PM Ca(2+) channels. This acts as a chaperoning step prior to 
      and in preparation for sequential assembly of exocyst and excitosome complexes 
      that mediate biphasic insulin secretion.
CI  - (c) 2013 John Wiley & Sons A/S.
FAU - Xie, Li
AU  - Xie L
AD  - Department of Physiology and Medicine, University of Toronto, Toronto, Ontario, 
      M5S 1A8, Canada.
FAU - Kang, Youhou
AU  - Kang Y
FAU - Liang, Tao
AU  - Liang T
FAU - Dolai, Subhankar
AU  - Dolai S
FAU - Xie, Huanli
AU  - Xie H
FAU - Parsaud, Leon
AU  - Parsaud L
FAU - Lopez, Jamie A
AU  - Lopez JA
FAU - He, Yu
AU  - He Y
FAU - Chidambaram, Subbulakshmi
AU  - Chidambaram S
FAU - Lam, Patrick P
AU  - Lam PP
FAU - James, David E
AU  - James DE
FAU - Sugita, Shuzo
AU  - Sugita S
FAU - Gaisano, Herbert Y
AU  - Gaisano HY
LA  - eng
GR  - MOP 86544/Canadian Institutes of Health Research/Canada
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130214
PL  - England
TA  - Traffic
JT  - Traffic (Copenhagen, Denmark)
JID - 100939340
RN  - 0 (Calcium Channels, L-Type)
RN  - 0 (Calcium Channels, R-Type)
RN  - 0 (Insulin)
RN  - 0 (Protein Subunits)
RN  - 0 (RNA, Small Interfering)
RN  - EC 3.6.1.- (Rala protein, rat)
RN  - EC 3.6.5.2 (ral GTP-Binding Proteins)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcium/metabolism
MH  - Calcium Channels, L-Type/genetics/*metabolism
MH  - Calcium Channels, R-Type/genetics/*metabolism
MH  - Cell Membrane/metabolism
MH  - Exocytosis
MH  - Fluorescence Resonance Energy Transfer
MH  - HEK293 Cells
MH  - Humans
MH  - Insulin/*metabolism
MH  - Insulin-Secreting Cells/metabolism
MH  - Protein Binding
MH  - Protein Subunits/genetics/*metabolism
MH  - Protein Transport
MH  - RNA, Small Interfering
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Secretory Vesicles/*metabolism
MH  - ral GTP-Binding Proteins/*metabolism
EDAT- 2013/01/26 06:00
MHDA- 2013/08/16 06:00
CRDT- 2013/01/26 06:00
PHST- 2012/03/06 00:00 [received]
PHST- 2013/01/21 00:00 [revised]
PHST- 2013/01/24 00:00 [accepted]
PHST- 2013/01/26 06:00 [entrez]
PHST- 2013/01/26 06:00 [pubmed]
PHST- 2013/08/16 06:00 [medline]
AID - 10.1111/tra.12047 [doi]
PST - ppublish
SO  - Traffic. 2013 Apr;14(4):428-39. doi: 10.1111/tra.12047. Epub 2013 Feb 14.