genome-wide screen for crac channels
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Genome-wide screen for Genome-wide screen for CRAC channels CRAC channels
Treat 104 S2 cells 5 days with dsRNA; load with fluo-4, wash 2 Ca2+ Ringer;3 fluorescence measurements per well:
basal , then add 1 M TG;
CCE , then lyse cells; Fmax
Calculate CCE / basal, filter out low Fmax
x 384 wells/platex 63 platesx 2 experimental runs for each dsRNA145,152 fluorescence measurements
5 d in well with dsRNA Fluo-4 wash lyse+TG
1 2 31
2
3
CC
E /
bas
al s
et 2
CCE / basal set 1
0 10000 20000-6
-3
0
3
6
Amplicon number
ZS
co
re o
f C
CE
/ b
asa
l
Genome-wide RNAi screen for SOC influx
1.0 1.50
250
500
1 2 30
4000
8000
# o
f am
plic
on
s
CCE / basal
Mea
n
olf
186-
FS
ec61
alp
ha
Syx
5 p vrcd
c16 CG
874
3 CG
1421
4 CG
4012
7S
yx1
A
Ca-
P60
AS
tim
Sti
m
Ave
1
2
CC
E /
ba
sa
l
hits with TMs
1
2
Top 10 hits
CC
E /
ba
sa
l
Mea
n Sti
mts
rcd
c23
olf
186-
Fd
om
Sec
61al
ph
aS
yx5
del
taC
OPS
tim
A
veEts
65A Ca-
P60
A
Genome-wide RNAi screen for SOC influx
0 500 10000
1
2
3
[C
a2+] i (
M)
Ca0 + TG
Ca0
Ca2
Time (s)0 500 1000
0
1
2
3
[Ca2+
] i (M
)
Ca0 + TG
Ca0
Ca2
Time (s)
Ca
0 +
T
G
Re
sti
n g
Ma
xim a
l
Su
sta
ine d
Ca
0
C
a2
0
1
2
3 CG11059 olf186-F
[Ca
2+] i (
M)
bp MdsRNA
CG11059
Stim olf186-F
600
500
400
Psn
600
400
300
500 Stim
CG11059200
100
300
400500
300olf186-F
200
100
BA C
D E F
0 200 400
-20
0
olf186-F
Control
I (pA
)
Time (s)
Ca2
0
4
8
12
I de
nsity
(pA
/pF
)Non-treated* CG11059 olf186-F
CG11059 olf186-F
RNAi knock-down of olf186-F inhibitsCa2+ influx and CRAC currents
Chromosome 7
12
16
olf186-F conserved gene family
Proposed olf186-F membrane topology
Chromosome 12 homolog (ORAI1) mutated from R to W in SCID patients Chromosome 12 homolog (ORAI1) mutated from R to W in SCID patients Feske Feske et alet al., ., NatureNature in press 2006 in press 2006
Ca-P60A
Stim
Psn
bp MdsRNA
CG11059 Stim Ca-P60A
400300
100
200
600
300
500400
CG11059
600500400
200
300
500600
400300
MbpdsRNA
CG11059 Stim Syx5600
300
500600
400Stim
600500400
200
300CG11059
Psn500600
400300
400500
300
200
Syx5
bp MdsRNA
CG11059 Stim tsr
600
400500
300
CG11059300
100
200
tsr200
300
100
Psn500400300
600
Stim
600
300
600500400
bp M500
Stim olf186-F Stim+olf186-FCont.
400
100
300200
300
500400
Stim
Psn
olf186-F
RT-PCR validation of overexpression or RNAi knockdown
Syntaxin 5dsRNA
tsrdsRNA
SERCAdsRNAolf186-F
Stim Xfection
Overexpression of olf186-F augments CRAC currents
BA
C D
0 250 500
-500
-250
0
Olf186-F + Stim
Olf186-F
Stim
ControlI (
pA)
Time (s)
Ca2
Ca20 (b)
-100 -50 50 100V (mV)
I (pA)
-200
-400
Ca2 (a)
0 250 500
-500
-250
0
0 100 200
-400
-200
0
0
50
100
0 200 400
-200
-100
0
0
20
40
EED
CBCa2
olf186-F + stim
olf186-F
Stim
Control
I (p
A)
Time (s)
ACa20Ca2
I (p
A)
Time (s)
a
bCa20 (b)
-100 -50 50 100V (mV)
I (pA)
-200
-400
Ca2 (a)
olf1
86-F
+st
im,
time 1/
2
olf1
86-F
+st
im,
dela
y
olf1
86-F
,
del
ay
olf1
86-F
,
tim
e 1/2
Tim
e (s
)I (p
A)
Time (s)
Delay
Time 1/2
50% of currenthas developed
olf1
86-F
+ s
tim*
olf1
86-F
stim
Con
trol
I de
nsity
(pA
/pF
)
Giant CRAC currents induced by olf186-F + Stim
BA
C D
0 150 300
-300
-150
0
CsNaI (
pA)
Time (s)
Ca2
c
a
b
Ca (a)
100
Na (b)
-100 -50 50V (mV)
I (pA)
-100
-200
Cs (c)
0 200 400
-200
-100
0
50 nM Gd3+
I (pA
)
Time (s)
Ca2
0 200 400
-200
-100
0
5 M 20 M 2-APB
I (pA
)
Time (s)
Ca2
PNa/PCs = 0.08
Inactivation of monovalent current
(divalent-free)
Potentiation
Block
Reversible block by gadolinium
Classic CRACJurkat T Cell
Lewis and Cahalan, 1989 Ca20 (b)
-100 -50 50 100V (mV)
I (pA)
-200
-400
Ca2 (a)
Giant CRACTransfected S2 Cell (olf + Stim)
Zhang, Yeromin and Cahalan, 2006
Magnifying CRAC Currents
From single-channel current noise estimate (7 fA at –110 mV), giant CRAC currents represent ~105 channels per cell, or 100 per m2
Accelerating CRAC current development by co-transfection of olf186-F with Stim
0 200 400
-200
-100
0
I (pA
)
Time (s)
Delay
Time 1/2
50% of currenthas developed
0 500 10000
1000
2000
Ca0 + TG
Ca0
[Ca
2+] i (
nM
)
Time (s)
Ca2
0 500 10000
1000
2000
Ca0 + TG
Ca0
[Ca2+
] i (n
M)
Time (s)
Ca2
0 500 10000
200
400
[Ca2
+] i (
nM
)
Time (s)
Ca2
Ca0
Ca0 + Iono
0 500 10000
200
400
[Ca2
+] i (
nM
)
Time (s)
Ca2
Ca0
Ca0 + Iono
SERCA knockdown
0
1000
2000
1 2 3 4
[Ca2+
] i (n
M)
0
4
8
12
Cu
rre
nt
de
nsi
ty (
pA
/pF
)
CG11059 SERCA Pump
BA
E F
C D
Reduced store content
Elevated resting [Ca2+]i
and decreased SOC
Decreased CRAC current
0 500 10000
1
2
Ca0 + TG
Ca0
Ca2
[Ca2+
] i (M
)
Time (s)0 500 1000
0
1
2
Ca0 + TGCa2
[Ca2+
] i (M
)
Ca0
Time (s)0 500 1000
0
1
2
Ca0 + TG
Ca0
Ca2
[Ca2+
] i (M
)
Time (s)
BA
E
C
D
CG11059 Syx5 tsr
Ca
0 +
T
G
Re
sti
n g
Ma
xim a
l
Su
sta
ine d
Ca
0
C
a2
Syntaxin 5 (and tsr) knockdown
Decreased SOC
Decreased CRAC current
CRAC SummaryCRAC Summary• RNAi screen for SOC and single cell validation identified RNAi screen for SOC and single cell validation identified StimStim, , olf186-Folf186-F, ,
SERCA, and Syntaxin 5: all are essential for CRAC channel function. SERCA, and Syntaxin 5: all are essential for CRAC channel function. Other hits also.Other hits also.
• Overexpression of Overexpression of StimStim alone does not increase CRAC current; alone does not increase CRAC current; olf186-Folf186-F 3X; 3X; olf186-Folf186-F + + StimStim 8X; faster activation kinetics. 8X; faster activation kinetics.
• Mutation of Mutation of StimStim or STIM1 EF hand activates CRAC. or STIM1 EF hand activates CRAC.
• STIM1 is mainly in ER. STIM1 EF hand is found mainly at the plasma STIM1 is mainly in ER. STIM1 EF hand is found mainly at the plasma membrane. membrane.
• Translocation of STIM1 to the plasma membrane is induced by store Translocation of STIM1 to the plasma membrane is induced by store depletion.depletion.
• StimStim may function as an ER Ca may function as an ER Ca2+2+ sensor that translocates to the plasma sensor that translocates to the plasma membrane to activate CRAC. membrane to activate CRAC. olf186-Folf186-F is a viable candidate for the channel. is a viable candidate for the channel. Other components? Vesicle trafficking mechanism (syntaxin 5), other? Other components? Vesicle trafficking mechanism (syntaxin 5), other?
CaCaSOC SOC
((olf186-Folf186-F))
IKCa1IKCa1
K+
TCR
CaM
Antigen
APC
MHC
Ca2+
Em
Kv1.3Kv1.3
CRAC channel activation pathway? CRAC channel activation pathway?
[Ca2+]i
ST
IM1
STIM1
Syntaxin5
Ca2+Ca2+
SERCA
Ca2+
IP3R
PLCγTK
DAG
PKC
IP3
PI(4,5)P2
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