Cloning, sequencing, and functional characterization of the vitamin D receptor in vitamin D-resistant New World primates.
New World primates (NWPs) have high circulating 1,25-dihydroxyvitamin D (1,25-(OH)2D) levels. Comparable levels would be harmful to Old World primates (OWPs) and humans. Thus, NWPs must have developed mechanisms of 1,25-(OH)2D resistance to survive. In humans, patients with hypocalcemic vitamin D-resistant rickets type II have high circulating vitamin D levels and vitamin D resistance due to expression of a dysfunctional vitamin D receptor (VDR). To examine if this could wholly or in part explain vitamin D resistance in NWPs, VDR from Saguinus oedipus (cotton top tamarin) NWP B95-8 cells was cloned by reverse-transcription polymerase chain reaction (RT-PCR). The NWP VDR cDNA sequence showed 96% homology at the DNA level and 98% homology at the amino acid level compared to human VDR. To assay for function, NWP VDR cDNA was transiently transfected into CV-1 cells with a vitamin D response element reporter plasmid. No difference between OWP and NWP VDR-directed transactivation was observed. These results indicate that the mechanism of vitamin D resistance in NWPs is not due to a dysfunctional VDR, and is consistent with our hypothesis that vitamin D resistance in NWPs is mediated by overexpression of a VDR-independent vitamin D response element binding protein.
Chun
R F
RF
Department of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
Chen
H
H
Boldrick
L
L
Sweet
C
C
Adams
J S
JS
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D001483:Base Sequence; D015153:Blotting, Western / Q000662:veterinary; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D018167:Receptors, Calcitriol / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012452:Saguinus / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015533:Transcriptional Activation; D014162:Transfection / Q000662:veterinary; D014807:Vitamin D / Q000502:physiology; D014809:Vitamin D-Binding Protein / Q000502:physiology
D018167:Receptors, Calcitriol; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; D004247:DNA