Endocrinology, Vol 124, 1184-1189, Copyright © 1989 by Endocrine Society

ARTICLES

Abnormal adenosine 3'.5'-monophosphate stimulation of renal 1,25- dihydroxyvitamin D production in hyp mice: evidence that 25- hydroxyvitamin D-1 alpha-hydroxylase dysfunction results from aberrant intracellular function

T Nesbitt, GA Davidai and MK Drezner
Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.

Previously we have established that abnormal regulation of renal 25- hydroxyvitamin D (25OHD)-1 alpha-hydroxylase in Hyp mice involves the PTH-adenylate cyclase component of enzyme activation. However, it remains unknown if the muted effects of PTH result from 1) abnormal second messenger production or 2) an intracellular defect limiting enzyme activation. To distinguish between these possibilities, we compared cAMP stimulation of renal 25OHD-1 alpha-hydroxylase in normal, phosphate-depleted normal, and Hyp mice. Administration of N6- monobutyryl cAMP iv (200 mg/kg/day) increased enzyme activity in normal (4.1 +/- 1.7 vs. 40.7 +/- 7.0 fmol/mg kidney.min) and phosphate- depleted mice (13.3 +/- 1.8 vs. 78.2 +/- 10.4) to a level significantly greater than that achieved in Hyp mice (7.4 +/- 1.1 vs. 22.7 +/- 3.6). Moreover, similar to our observations after PTH stimulation, the apparent abnormal cAMP effect did not result from an altered time course of enzyme activation or a rightward shift in the dose response. Collectively, these data indicate that abnormal regulation of 1,25- dihydroxyvitamin D production in Hyp mice results from aberrant intracellular regulation of 25OHD-1 alpha-hydroxylase, a defect probably related to deranged phosphate transport in the renal tubule.

This article has been cited by other articles:

				B. Yuan, Y. Xing, R. L. Horst, and M. K. Drezner Evidence for Abnormal Translational Regulation of Renal 25-Hydroxyvitamin D-1{alpha}-Hydroxylase Activity in the Hyp-Mouse Endocrinology, August 1, 2004; 145(8): 3804 - 3812. [Abstract] [Full Text] [PDF]

				N. Azam, M. Y. H. Zhang, X. Wang, H. S. Tenenhouse, and A. A. Portale Disordered Regulation of Renal 25-Hydroxyvitamin D-1{alpha}-Hydroxylase Gene Expression by Phosphorus in X-Linked Hypophosphatemic (Hyp) Mice Endocrinology, August 1, 2003; 144(8): 3463 - 3468. [Abstract] [Full Text] [PDF]

				H. S. Tenenhouse, J. Martel, C. Gauthier, M. Y. H. Zhang, and A. A. Portale Renal Expression of the Sodium/Phosphate Cotransporter Gene, Npt2, Is Not Required for Regulation of Renal 1{{alpha}}-Hydroxylase by Phosphate Endocrinology, March 1, 2001; 142(3): 1124 - 1129. [Abstract] [Full Text] [PDF]