Hydroxylases involved in vitamin D metabolism are differentially expressed in murine embryonic kidney: application of whole mount in situ hybridization.
In this study we examined the expression of 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase) and 25-hydroxyvitamin D-24-hydroxylase (24-hydroxylase) by RT-PCR and whole mount in situ hybridization using organ culture of kidney taken from mouse embryo. First, the kidneys of mouse embryo at 11.5-17.5 days gestation were cultured in the presence or absence of forskolin and 1,25-dihydroxyvitamin D(3) [1alpha,25-(OH)(2)D(3)]. Forskolin and 1alpha,25-(OH)(2)D(3) induced the expression of 1alpha-hydroxylase and 24-hydroxylase, respectively, in a dose- and time-dependent manner. In the absence of stimulants, the expression of 1alpha-hydroxylase and 24-hydroxylase was detected from days 13.5-17.5 gestation. The expression of vitamin D receptor and megalin was detected from days 13.5 and 11.5, respectively. Next, signals for the expression of either 1alpha-hydroxylase or 24-hydroxylase were detected by whole mount in situ hybridization in kidney explants taken from embryo at 15.5 days gestation after the appropriate stimulation. However, the localization of signals differed between the two enzymes; 1alpha-hydroxylase messenger RNA was expressed in the inner area of the kidney explants, whereas 24-hydroxylase messenger RNA was expressed in the surface area. The expression of both hydroxylases was restricted to the epithelium of developing renal tubules. The pattern of megalin expression was similar to that of 1alpha-hydroxylase expression. To confirm the difference in distribution of 1alpha-hydroxylase and 24-hydroxylase transcripts, the explants were hybridized with probes for both 1alpha-hydroxylase and 24-hydroxylase using double labeling techniques after simultaneous stimulation with forskolin and 1alpha,25-(OH)(2)D(3), resulting in the detection at different locations of positive signals for the two enzymes. These results suggest that the expression of 1alpha-hydroxylase is induced in a distinct epithelium of renal tubules from that of 24-hydroxylase even at the early stage of kidney development before glomerulogenesis.
Yamagata
M
M
Department of Environmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan.
Kimoto
A
A
Michigami
T
T
Nakayama
M
M
Ozono
K
K
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism; D005260:Female; D026541:Heymann Nephritis Antigenic Complex; D017403:In Situ Hybridization; D007668:Kidney / Q000196:embryology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D014807:Vitamin D / Q000378:metabolism*; D065668:Vitamin D3 24-Hydroxylase
D026541:Heymann Nephritis Antigenic Complex; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D014807:Vitamin D; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase