SRP/dGATAb modulates the ecdysone response bidirectionally via locus-specific regulatory landscape

Area of Science:

• Developmental Biology
• Molecular Endocrinology
• Genomics

Background:

• Steroid hormones regulate gene transcription via enhancers.
• Mechanisms of enhancer targeting by nuclear receptors are not fully understood.
• Cooperation between nuclear receptors and transcription factors is proposed but limitedly studied.

Purpose of the Study:

• To investigate the role of SRP/dGATAb in 20-hydroxyecdysone (20E) transcriptional responses in Drosophila S2 cells.
• To determine the genome-wide impact of SRP/dGATAb depletion on 20E-induced genes.

Main Methods:

• RNA interference (RNAi) to deplete SRP/dGATAb.
• RNA-sequencing (RNA-Seq) to analyze gene expression changes.
• Chromatin immunoprecipitation sequencing (ChIP-Seq) to identify DNA binding sites and histone modifications (H3K27Ac).

Main Results:

• SRP/dGATAb depletion altered transcription of 20E-induced genes.
• For a subset of genes, SRP/dGATAb depletion decreased expression, indicating a positive regulatory role.
• In these cases, SRP/dGATAb facilitated EcR binding and chromatin acetylation, confirming its priming function.

Conclusions:

• SRP/dGATAb acts as a priming factor for 20E-inducible transcription, enhancing EcR recruitment and chromatin acetylation for specific genes.
• Conversely, SRP/dGATAb negatively regulates another subset of 20E-inducible genes, restraining enhancer activity.