HNF4alpha and NF-E2 are key transcriptional regulators of the murine Abcc6 gene expression.
Mutations in an ABC transporter gene called ABCC6 are responsible for pseudoxanthoma elasticum (PXE), a rare heritable disease characterized by elastic fiber calcification in skin, ocular and vascular tissues. The presumed function of this ABC transporter is to export metabolites from polarized cells. However, the endogenous substrate(s) are unknown and the exact relationship with elastic fibers is unclear. As ABCC6 is only expressed at high level in liver and kidneys, tissues seemingly unrelated to the PXE phenotype, we explored the transcriptional regulation of the murine Abcc6 gene to define the transcriptional signal conferring tissue specificity and to gather clues on its possible biological function. We cloned 2.9 kb of the mAbcc6 5'-flanking region and several deletion constructs linked to a luciferase reporter gene. We delineated a proximal promoter and a liver-specific enhancer region. We also demonstrated that the proximal region is a TATA-less promoter requiring an intact CCAAT-box and Sp1 binding for its basal activity. By using reporter assays and chromatin immunoprecipitations, we showed that HNF4alpha and surprisingly, NF-E2, enhanced the mAbcc6 promoter activity. The involvement of both HNF4alpha and NF-E2 in the mAbcc6 gene regulation suggests that Abcc6 might be involved in a detoxification processes related to hemoglobin or heme.
Douet
Vanessa
V
Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, BSB 222, Honolulu, HI 96813, USA.
VanWart
Christopher M
CM
Heller
Matthew B
MB
Reinhard
Sabrina
S
Le Saux
Olivier
O
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D050984:NF-E2 Transcription Factor, p45 Subunit / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015533:Transcriptional Activation
D018528:ATP-Binding Cassette Transporters; D018076:DNA, Complementary; D051557:Hepatocyte Nuclear Factor 4; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D050984:NF-E2 Transcription Factor, p45 Subunit; C504743:Abcc6 protein, mouse; C496593:Hnf4a protein, mouse; C494693:Nfe2 protein, mouse