Regulation of the Mouse Treacher Collins Syndrome Homolog (Tcof1) Promoter Through Differential Repression of Constitutive Expression

Abstract

Treacher Collins syndrome is an autosomal-dominant mandibulofacial dysostosis caused by haploinsufficiency of the TCOF1 gene product treacle. Mouse Tcof1 protein is approximately 61% identical and 71% similar to treacle, and heterozygous knockout of Tcof1 causes craniofacial malformation. Tcof1 expression is high in developing neural crest, but much lower in other tissues. To investigate this dual regulation, highly conserved regions upstream of TCOF1 homologs were tested through deletion and mutation reporter assays, and conserved predicted transcription factor binding sites were assessed through chromatin binding studies. Assays were performed in mouse P19 embryonic carcinoma cells and in HEK293 cells to determine differential activation in cell types at different stages of differentiation. Binding of Cebpb, Zfp161, and Sp1 transcription factors was specific to the Tcof1 regulatory region in P19 cells. The Zfp161 binding site demonstrated P19 cell-specific repression, while the Sp1/Sp3 candidate site demonstrated HEK293 cell-specific activation. Moreover, presence of c-myb and Zfp161 transcripts was specific to P19 cells. A minimal promoter fragment from -253 to +43 bp directs constitutive expression in both cell types, and dual regulation of Tcof1 appears to be through differential repression of this minimal promoter. The CpG island at the transcription start site remains unmethylated in P19 cells, 11.5 dpc mouse embryonic tissue, and adult mouse ear, which supports constitutive activation of the Tcof1 promoter.

TCOF1 upregulation in triple-negative breast cancer promotes stemness and tumour growth and correlates with poor prognosis

“…One hundred and twenty-seven candidate TFs binding to e1 were identified (Table S4 ). Of these candidates, YY1 and c-MYB have been shown to bind to the promoter of TCOF1 [ 48 , 49 ], whereas PLAG1 and FOSL1 were demonstrated to regulate TNBC enhancer activities [ 50 ]. These four candidates will be prioritised for examining their function in mediating TCOF1 overexpression via super-enhancer in future studies.…”

“…A computational pipeline has recently been developed to identify transcribed enhancers in breast cancer and demonstrated that TFs such as FOSL1 and PLAG1 play key roles in regulating the activities of TNBC enhancers [ 50 ]. In addition, a few TFs, including YY1, Cebpb, Zfp161, Sp1 and c-MYB, have been described to bind to TCOF1 promoter and modulate its expression [ 48 , 49 ]. Our bioinformatic analysis on TF binding predicts that FOSL1, PLAG1, YY1 and c-MYB bind to e1 region of SE324 in TNBC cells.…”

The Role of TCOF1 Gene in Health and Disease: Beyond Treacher Collins Syndrome

“…Firstly, the mechanisms governing spatiotemporal regulation of TCOF1 expression are largely unknown. The studies on transcriptional TCOF1 regulators gave inconclusive results [ 18 ]. Since ribosome biogenesis can be regulated by non-coding RNAs [ 103 ], it may suggest that TCOF1 could be a target of such regulation.…”

“…TCOF1 has been localized to the long arm of chromosome 5, at the 5q32-33.3 locus between the CSF1R and SPARC genes [ 11 , 16 , 17 ]. The human and mouse promoters of TCOF1 gene include several predicted binding sites of transcription factors (e.g., c-myb, CCAAT, Zfp161, Sp1/Sp3, and AP2α), however, their functional significance is disputable [ 18 ].…”

Globularization and Domestication

“…TCOF1 is a candidate for Treacher Collins syndrome, an autosomal-dominant condition involving mandibulofacial dysostosis. Heterozygous knockout of Tcof1 in mice causes severe craniofacial malformation (Dixon and Dixon 2004;Shows and Shiang 2008).…”