The transcription factor NF-κB plays an important role in the immune system, apoptosis and inflammation. Dorsal, a Drosophila homolog of NF-κB, patterns the dorsal-ventral axis in the blastoderm embryo. During this stage, Dorsal is sequestered outside the nucleus by the IκB homolog Cactus. Toll signaling on the ventral side breaks the Dorsal/Cactus complex, allowing Dorsal to enter the nucleus to regulate target genes. Fluorescent data show that Dorsal accumulates on the ventral side of the syncytial blastoderm. Here, we use modeling and experimental studies to show that this accumulation is caused by facilitated diffusion, or shuttling, of the Dorsal/Cactus complex. We also show that active Toll receptors are limiting in wild-type embryos, which is a key factor in explaining global Dorsal gradient formation. Our results suggest that shuttling is necessary for viability of embryos from mothers with compromised dorsal levels. Therefore, Cactus not only has the primary role of regulating Dorsal nuclear import, but also has a secondary role in shuttling. Given that this mechanism has been found in other, independent, systems, we suggest that it might be more prevalent than previously thought.
yw
All lsm files (images taken with a Zeiss 710) of yw embryos used in the analysis (quantitative or qualitative) in this paper.
dl hets
All lsm files (images taken with a Zeiss 710) of dl heterozygous embryos used in the analysis (quantitative or qualitative) in this paper.
dl_+.zip
dl-paGFP
All lsm files (images taken with a Zeiss 710) of dl-paGFP embryos used in the analysis (quantitative or qualitative) in this paper.
dl,dl-mGFP/+
All lsm files (images taken with a Zeiss 710) of dl,dl-mGFP/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have one copy of endogenous dl, and one copy of dl-mGFP.
dl,dl-mGFP_+.zip
dl/+;dl-dGFP/+
All lsm files (images taken with a Zeiss 710) of dl/+;dl-dGFP/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have one copy of endogenous dl, and one copy of dl-dGFP.
dl_+;dl-dGFP_+.zip
dl;dl-dGFP
All lsm files (images taken with a Zeiss 710) of dl;dl-dGFP embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have zero copies of endogenous dl, and two copies of dl-dGFP.
dl;dl-dGFP/+
All lsm files (images taken with a Zeiss 710) of dl;dl-dGFP/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have zero copies of endogenous dl, and one copy of dl-dGFP.
dl;dl-dGFP_+.zip
dl/+;Tlrv18/+
All lsm files (images taken with a Zeiss 710) of dl/+;Tlrv18/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos are heterozygous for dl and also for Tl.
dl_+;Tlrv18_+.zip
Egfr[t1]/+
All lsm files (images taken with a Zeiss 710) of Egfr[t1]/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos are heterozygous for the hypomorphic allele Egfr[t1].
Egfrt1_+.zip
EGFRt1
All lsm files (images taken with a Zeiss 710) of Egfr[t1] embryos used in the analysis (quantitative or qualitative) in this paper. These embryos are homozygous for the hypomorphic allele Egfr[t1].
Egfrt1;dlRC/+
All lsm files (images taken with a Zeiss 710) of Egfr[t1];dl[RC]/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos are homozygous for the hypomorphic allele Egfr[t1] and transgenically carry an extra copy of dl (so three copies of full length dl: two endogenous, one transgenic).
Egfrt1;dlRC_+.zip
Egfrt1;dlRC
All lsm files (images taken with a Zeiss 710) of Egfr[t1];dl[RC] embryos used in the analysis (quantitative or qualitative) in this paper. These embryos are homozygous for the hypomorphic allele Egfr[t1] and transgenically carry two extra copies of dl (so four copies of full length dl: two endogenous, two transgenic).
bcd-Toll10b-bcd3'UTR
All lsm files (images taken with a Zeiss 710) of bcd-Toll10b-bcd3'UTR embryos used in the analysis (quantitative or qualitative) in this paper. These embryos transgenically a Toll10b-bcd 3' UTR construct, driven by the bcd promoter.
gd[7];bcd-Toll10b-bcd3'UTR
All lsm files (images taken with a Zeiss 710) of gd[7];bcd-Toll10b-bcd3'UTR embryos used in the analysis (quantitative or qualitative) in this paper. These embryos transgenically a Toll10b-bcd 3' UTR construct, driven by the bcd promoter, in a gd[7] background.
gd7;bcd-Toll10b-bcd3'UTR.zip
gd[7];hsp83-Toll10b-bcd3'UTR
All lsm files (images taken with a Zeiss 710) of gd[7];hsp83-Toll10b-bcd3'UTR embryos used in the analysis (quantitative or qualitative) in this paper. These embryos transgenically a Toll10b-bcd 3' UTR construct, driven by the hsp83 promoter, in a gd[7] background.
gd7;hsp83-Toll10b-bcd3'UTR.zip
dl,dl-mGFP,H2A-RFP/+ for bleaching
All lsm files (images taken with a Zeiss 710) of dl,dl-mGFP,H2A-RFP/+ embryos used in the analysis (quantitative or qualitative) in this paper. For photobleaching.
dl,dl-mGFP,H2A-RFP_+ for bleaching.zip
dl/+;dl-dGFP,H2A-RFP/+ for bleaching
All lsm files (images taken with a Zeiss 710) of dl/+;dl-dGFP,H2A-RFP/+ embryos used in the analysis (quantitative or qualitative) in this paper. For photobleaching.
dl_+;dl-dGFP,H2A-RFP_+ for bleaching.zip
dl/+;dl-dVenus/+
All lsm files (images taken with a Zeiss 710) of dl/+;dl-dVenus/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have one copy of endogenous dl, and one copy of dl-dVenus.
dl_+;dl-dVenus_+.zip
dl/+;dl-mVenus/+
All lsm files (images taken with a Zeiss 710) of dl/+;dl-mVenus/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have one copy of endogenous dl, and one copy of dl-mVenus.
dl_+;dl-mVenus_+.zip
dl;dl-mVenus
All lsm files (images taken with a Zeiss 710) of dl;dl-mVenus embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have zero copies of endogenous dl, and two copies of dl-mVenus.
dl;dl-mVenus/+
All lsm files (images taken with a Zeiss 710) of dl;dl-mVenus/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have zero copies of endogenous dl, and one copy of dl-mVenus.
dl;dl-mVenus_+.zip
dl;dl-lacZ
All lsm files (images taken with a Zeiss 710) of dl;dl-lacZ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have zero copies of endogenous dl, and two copies of dl-lacZ.
cact/+;cact-lacZ/+
All lsm files (images taken with a Zeiss 710) of cact/+;cact-lacZ/+ embryos used in the analysis (quantitative or qualitative) in this paper. These embryos have one copy of endogenous cact, and one copy of cact-lacZ
cact_+;cact-lacZ_+.zip