1,25-dihydroxyvitamin d3 receptor ontogenesis in fetal renal
development.
Johnson, Julie A., Joseph P. Grande, Patrick C. Roche, William E.
Sweeney, Jr, Ellis D. Avner, and Rajiv Kumar.
Nephrology Research Unit, Departments of Medicine and Biochemistry
and Molecular Biology, and Laboratory Medicine, Mayo
Clinic/Foundation, Rochester, MN, and the Division of Pediatric
Nephrology, Department of Pediatrics, Children's Hospital and Medical
Center, and the University of Washington, Seattle, WA
APStracts 2:0083F, 1995.
We used immunohistochemical techniques to examine the distribution of
1,25-dihydroxyvitamin D3 receptors (VDR) in developing rat and mouse
kidneys and murine metanephric organ culture. In vivo, the patterns
of expression in the two species were similar despite the slight
difference in gestational periods (rat 22 days; mouse 19 days).
Starting at gestational day 15, epitopes for VDR were found in cells
of branching ureteral buds and in surrounding mesenchyme, and at
later developmental stages in glomerular visceral and parietal
epithelial cells, and proximal and distal tubules. Epitopes for the
28 kD calcium-binding protein (calbindin-D28k) were found exclusively
in distal tubules starting at gestational day 19. The pattern of VDR
expression during in vitro nephrogenesis in serum-free murine
metanephric organ culture paralleled that seen in vivo. At the time
of explantation into organ culture (gestational day 13) VDR epitopes
were not detected. By 3 days of in vitro development, VDR expression
was identical to that found in gestational day 15 metanephroi in
vivo. VDR expression following 5 days of in vitro development
mirrored the pattern of gestational day 17 metanephroi in vivo. No
calbindin-D28k epitopes were seen at any in vitro developmental stage
studied. We demonstrate for the first time that VDR are present in
specific areas of the developing rat and mouse kidney early in
gestation. Calbindin-D28k appears later in developing rat and mouse
kidney and is distributed differently than the VDR. Metanephric organ
culture may be a useful model for studying the regulation and
function of VDR during early renal development.
Received 2 December 1994; accepted in final form 4 May 1995.
APS Manuscript Number F426-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 26 May 1995.