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bioRxiv
BIORXIV
bioRxiv
Cold Spring Harbor Laboratory

10.1101/2024.05.20.595009
preprint
1
Article
Target gene responses differ when transcription factor levels are acutely decreased by nuclear export versus degradation
McGehee James
Stathopoulos Angelike http://orcid.org/0000-0001-6597-2036

20 5 2024
2024.05.20.595009http://biorxiv.org/lookup/doi/10.1101/2024.05.20.595009
nihpp-2024.05.20.595009.pdf
ABSTRACT

Defining the time of action for morphogens requires tools capable of temporally controlled perturbations. To study how the transcription factor Dorsal affects patterning of the Drosophila embryonic dorsal-ventral axis, we used two light-inducible tags that result in either nuclear export or degradation of Dorsal when exposed to blue light. Nuclear export of Dorsal results in loss of expression for the high threshold, ventrally-expressed target gene snail ( sna ) but retention of the low threshold, laterally-expressed target gene short-gastrulation ( sog ). In contrast, degradation of Dorsal results in retention of sna, loss of sog , and lower nuclear levels than when Dorsal is exported from the nucleus. To elucidate how nuclear export results in loss of sna but degradation does not, we investigated Dorsal kinetics using photobleaching and found it reenters the nucleus even under conditions of blue-light when export is favored. The associated kinetics of being imported and exported continuously are likely responsible for loss of sna but, alternatively, can support sog . Collectively, our results show that this dynamic patterning process is influenced by both Dorsal concentration and nuclear retention.

SUMMARY STATEMENT

This study shows how optogenetic tools can be used to determine how a transcription factor’s levels and nuclear retention impact a dynamic patterning process.
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