International Mammalian Genome Society

The 15th International Mouse Genome Conference (2001)


POSTER 83 - AN ABD-B CLASS HOX/PBX RECOGNITION SEQUENCE IS EQUIRED FOR EXPRESSION FROM THE MOUSE REN-1C GENE

Li Pan
Dept of Molecular & Cellular Biology
Roswell Park Cancer Institute
Buffalo New York 14263

Co-Authors: Xie Y, Black TA, Jones CA, Pruitt SC, Gross KW
Institutions: Dept of Molecular & Cellular Biology, Roswell Park Cancer Institute

Expression from the mouse Ren-1c gene in As4.1 cells is dependent on a proximal promoter element (PPE), located at approximately -60, and a 241 base pair (bp) enhancer region, located at -2625, relative to the transcription site.  The PPE (TAATAAATCAA) is identical to a consensus Hox/Pbx binding sequence. Further, Pbx1b was shown to be a component of a PPE specific binding complex present in nuclear extracts from As4.1 cells. The binding affinities of different paralog Hox members to the PPE were examined in the absence or presence of Pbx1b. HoxB6, B7 and C8 failed to bind the PPE alone but showed weak affinity in the presence of Pbx1b. In contrast, HoxD10, and to a lesser degree Hox B9, bound the PPE with high affinities regardless of whether Pbx1b was present. Abd-B Hox members, including HoxD10, A10, A9, B9 and C9, are expressed in As4.1 cells. The ability of Hox and Pbx1b to from a ternary complex with Prep1, on the PPE, is also demonstrated both in vivo and in vitro. Point mutations in either the Hox or Pbx half site of the PPE disrupted the formation of the Hox/Pbx complex and dramatically decreased transcriptional activity of the Ren-1c gene, demonstrating that both the Hox and Pbx half sites are critical for mouse renin gene expression. These results strongly implicate Abd-B class Hox genes, and their co-factors, as major determinants of the sites of renin expression.


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