Intron retention generates a novel isoform of the murine vitamin D receptor that acts in a dominant negative way on the vitamin D signaling pathway.
We identified and characterized a novel rat vitamin D receptor isoform (rVDR1), which retains intron 8 of the canonical VDR (rVDR0) during alternative splicing. In this isoform protein directed by the stop codon in this newly identified exon, a part of the ligand binding domain (86 amino acids) is truncated at the C-terminal end but contains 19 extra amino acids. The rVDR1 transcript was expressed at a level 1/15 to 1/20 of that of rVDR0 in the kidney and intestine in adult rats but not in embryos. The recombinant rVDR1 protein showed no ligand binding activity. Homo- and heterodimers of the recombinant rVDR0 and rVDR1 proteins bound to a consensus vitamin D response element (VDRE) but not to consensus response elements for thyroid hormone and retinoic acid. However, unlike rVDR0, rVDR1 did not form a heterodimeric complex with RXR on the VDRE. A transient expression assay showed that this isoform acted as a dominant negative receptor against rVDR0 transactivation. Interestingly, the dominant negative activities of rVDR1 differed among VDREs. Thus, the present study indicates that this new VDR isoform negatively modulates the vitamin D signaling pathway, through a particular set of target genes.
Ebihara
K
K
Department of Agricultural Chemistry, Tokyo University of Agriculture, Setagayaku, Japan.
Masuhiro
Y
Y
Kitamoto
T
T
Suzawa
M
M
Uematsu
Y
Y
Yoshizawa
T
T
Ono
T
T
Harada
H
H
Matsuda
K
K
Hasegawa
T
T
Masushige
S
S
Kato
S
S
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002117:Calcitriol / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D004622:Embryo, Mammalian; D006367:HeLa Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007438:Introns; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D051381:Rats; D018167:Receptors, Calcitriol / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D018168:Receptors, Retinoic Acid / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping; D047488:Retinoid X Receptors; D015398:Signal Transduction; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D014162:Transfection; D014807:Vitamin D / Q000378:metabolism*
D015345:Oligonucleotide Probes; D018167:Receptors, Calcitriol; D018168:Receptors, Retinoic Acid; D011993:Recombinant Fusion Proteins; D047488:Retinoid X Receptors; D014157:Transcription Factors; D014807:Vitamin D; D015500:Chloramphenicol O-Acetyltransferase; D002117:Calcitriol