Attenuation of Forkhead signaling by the retinal determination factor DACH1

Abstract

The Drosophila Dachshund (Dac) gene, cloned as a dominant inhibitor of the hyperactive growth factor mutant ellipse, encodes a key component of the retinal determination gene network that governs cell fate. Herein, cyclic amplification and selection of targets identified a DACH1 DNA-binding sequence that resembles the FOX (Forkhead box-containing protein) binding site. Genome-wide in silico promoter analysis of DACH1 binding sites identified gene clusters populating cellular pathways associated with the cell cycle and growth factor signaling. ChIP coupled with high-throughput sequencing mapped DACH1 binding sites to corresponding gene clusters predicted in silico and identified as weight matrix resembling the cyclic amplification and selection of targets-defined sequence. DACH1 antagonized FOXM1 target gene expression, promoter occupancy in the context of local chromatin, and contactindependent growth. Attenuation of FOX function by the cell fate determination pathway has broad implications given the diverse role of FOX proteins in cellular biology and tumorigenesis.cell fate determination | Forkhead protein | transcription factor | tumor suppressor | dachshund homolog 1

Conserved role for the Dachshund protein with Drosophila Pax6 homolog Eyeless in insulin expression

“…Mutations in the Pax6 locus cause impaired insulin secretion, early-onset diabetes mellitus, and aniridia (16,32,33). A recent genome-wide in silico promoter analysis identified Glucagon and Igf2 as potential targets of mammalian Dach1 (34). In addition, a diet-induced β-cell-dysfunction analysis in mice identified that the altered expression of several genes, including Dach1, is correlated significantly with data from genome-wide association studies for type 2 diabetes in humans (35).…”

Transcription Elongation Regulator 1 Is a Co-integrator of the Cell Fate Determination Factor Dachshund Homolog 1

“…Antibodies used for IP and WB were: anti-T7; (Bethyl Laboratories, Montgomery, TX), anti-FLAG (M2 clone; Sigma), anti-FOXM1 (C20; Santa Cruz), and anti-DACH1 (Abcam; Cambridge, MA). ChIP analysis was performed following a protocol described previously (14).…”

“…A DACH1-specific DNA binding sequence was recently identified (14). To characterize the biological significance of DACH1 DNA binding further, we cloned a 13-bp DACH1 binding sequence, designated as DRE, into pGL3 luciferase reporter vectors pGL3-SV40 and pGL3-basic (Promega).…”

“…DACH1 is capable of binding both naked DNA and the chromatin DNA template through its Box-N domain, and the DNA binding is independent of protein association with other DACH1-binding partners (13). A subsequent study using cyclic amplification and selection of targets (CAST) identified a DNA sequence that is specific for DACH1 binding (14). The DACH1 DNA binding sequence resembles a Forkhead protein binding site, and DACH1 competes with FOXM1 from being recruited to the promoter of FOXM1 target genes.…”

“…Deregulation of FOX protein function in human tumorigenesis may occur by alteration in upstream regulators or genetic events such as mutations of the DNA binding domain (DBD), or translocations, which often disrupt the DBD. DACH1 inhibits FOXM1-mediated contact-independent growth, and DACH1 occupancy displaces FOXM1 in the context of local chromatin from the promoter of FOXM1-targeted genes including CDC25B, SKP2, and CDH1 (14).…”