Cdx1 autoregulation is governed by a novel Cdx1-LEF1 transcription complex.
The Cdx1 gene product is essential for normal anterior-posterior vertebral patterning. Expression of Cdx1 is regulated by several pathways implicated in anterior-posterior patterning events, including retinoid and Wnt signaling. We have previously shown that retinoic acid plays a key role in early stages of Cdx1 expression at embryonic day 7.5 (E7.5), while both Wnt3a signaling and an autoregulatory loop, dependent on Cdx1 itself, are involved in later stages of expression (E8.5 to E9.5). This autoregulation is reflected by the ability of Cdx1 to affect expression from proximal Cdx1 promoter sequences in tissue culture. However, this region is devoid of a demonstrable Cdx response element(s). We have now found that Cdx1 and LEF1, a nuclear effector of Wnt signaling, synergize to induce expression from the Cdx1 promoter through previously documented LEF/T-cell factor response elements. We also found a direct physical interaction between the homeodomain of Cdx1 and the B box of LEF1, suggesting a basis for this synergy. Consistent with these observations, analysis of Cdx1 Wnt3a(vt) compound mutants demonstrated that Wnt and Cdx1 converged on Cdx1 expression and vertebral patterning in vivo. Further data suggest that Cdx-high-mobility group box interactions might be involved in a number of additional pathways.
Béland
Mélanie
M
Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7.
Pilon
Nicolas
N
Houle
Martin
M
Oh
Karen
K
Sylvestre
Jean-René
JR
Prinos
Panagiotis
P
Lohnes
David
D
D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D024002:HMGB Proteins; D018398:Homeodomain Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism*; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
C491272:Cdx1 protein, mouse; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D018398:Homeodomain Proteins; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; D009687:Nuclear Proteins; D012333:RNA, Messenger; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse; D014157:Transcription Factors