Bab2 Functions as an Ecdysone-Responsive Transcriptional Repressor during Drosophila Development
Jianli Duan,
Yunpo Zhao,
Haichao Li,
Lukas Habernig,
Michael D. Gordon,
Xuexia Miao,
Ylva Engström,
Sabrina Büttner
Affiliations
Jianli Duan
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden; CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
Yunpo Zhao
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden; CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China; Department of Zoology, Life Science Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Corresponding author
Haichao Li
CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
Lukas Habernig
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
Michael D. Gordon
Department of Zoology, Life Science Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
Xuexia Miao
CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
Ylva Engström
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
Sabrina Büttner
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden; Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; Corresponding author
Summary: Drosophila development is governed by distinct ecdysone steroid pulses that initiate spatially and temporally defined gene expression programs. The translation of these signals into tissue-specific responses is crucial for metamorphosis, but the mechanisms that confer specificity to systemic ecdysone pulses are far from understood. Here, we identify Bric-à-brac 2 (Bab2) as an ecdysone-responsive transcriptional repressor that controls temporal gene expression during larval to pupal transition. Bab2 is necessary to terminate Salivary gland secretion (Sgs) gene expression, while premature Bab2 expression blocks Sgs genes and causes precocious salivary gland histolysis. The timely expression of bab2 is controlled by the ecdysone-responsive transcription factor Broad, and manipulation of EcR/USP/Broad signaling induces inappropriate Bab2 expression and termination of Sgs gene expression. Bab2 directly binds to Sgs loci in vitro and represses all Sgs genes in vivo. Our work characterizes Bab2 as a temporal regulator of somatic gene expression in response to systemic ecdysone signaling.
