The Central Region of the Drosophila Co-repressor Groucho as a Regulatory Hub.
Groucho (Gro) is a Drosophila co-repressor that regulates the expression of a large number of genes, many of which are involved in developmental control. Previous studies have shown that its central region is essential for function even though its three domains are poorly conserved and intrinsically disordered. Using these disordered domains as affinity reagents, we have now identified multiple embryonic Gro-interacting proteins. The interactors include protein complexes involved in chromosome organization, mRNA processing, and signaling. Further investigation of the interacting proteins using a reporter assay showed that many of them modulate Gro-mediated repression either positively or negatively. The positive regulators include components of the spliceosomal subcomplex U1 small nuclear ribonucleoprotein (U1 snRNP). A co-immunoprecipitation experiment confirms this finding and suggests that a sizable fraction of nuclear U1 snRNP is associated with Gro. The use of RNA-seq to analyze the gene expression profile of cells subjected to knockdown of Gro or snRNP-U1-C (a component of U1 snRNP) showed a significant overlap between genes regulated by these two factors. Furthermore, comparison of our RNA-seq data with Gro and RNA polymerase II ChIP data led to a number of insights, including the finding that Gro-repressed genes are enriched for promoter-proximal RNA polymerase II. We conclude that the Gro central domains mediate multiple interactions required for repression, thus functioning as a regulatory hub. Furthermore, interactions with the spliceosome may contribute to repression by Gro.
From the Departments of Chemistry and Biochemistry and.
Pak N
PN
Kwong
From the Departments of Chemistry and Biochemistry and.
Michael
M
Chambers
Biological Chemistry and.
Ajay A
AA
Vashisht
From the Departments of Chemistry and Biochemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095.
Wiam
W
Turki-Judeh
From the Departments of Chemistry and Biochemistry and.
Tak Yu
TY
Yau
Biological Chemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095.
James A
JA
Wohlschlegel
From the Departments of Chemistry and Biochemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095 courey@chem.ucla.edu.
Albert J
AJ
Courey
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004330:Drosophila; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D017381:Spliceosomes; D014158:Transcription, Genetic
D051792:Basic Helix-Loop-Helix Proteins; D012097:Repressor Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; C091023:gro protein, Drosophila
Groucho; intrinsically disordered domain; protein complex; proteomics; spliceosome; transcription corepressor; transcription regulation