| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
2 Veterans Affairs Medical Center, Long Beach 90822, and 1 University of California, Irvine, California 92697
Biotin, an essential water-soluble micronutrient, cannot be synthesized by mammals; rather, it is obtained from exogenous sources via uptake by intestinal epithelia. Renal epithelia reclaim the vitamin that is filtered in the glomeruli. Both epithelia take up biotin via the sodium-dependent multivitamin transporter (SMVT). Little is known about ontogenic regulation of the renal and intestinal biotin transport processes and about the mechanism(s) involved in any such regulation. In this study, we sought to examine and compare ontogenic aspects of the renal and intestinal biotin uptake processes using purified brush-border membrane vesicles (BBMV) isolated from the kidney cortex and jejunum of suckling and adult rats. Clear ontogenic changes were observed in the intestinal biotin uptake process, which were mediated via changes in Vmax and apparent Km. Parallel changes were also seen in protein, mRNA, and transcription rate of SMVT as indicated by results of Western blotting, RT-PCR, and nuclear run-on assays, respectively. In contrast, biotin uptake by renal BBMV did not show ontogenic changes; i.e., it was similar in suckling and adult rats. Also, the levels of SMVT protein and mRNA were similar in the kidneys of both age groups. These data show that biotin uptake by renal and intestinal epithelial cells responds differently to ontogenic regulation. In addition, the ontogenic changes observed in the intestinal biotin uptake process involve the entry step of the vitamin at the BBM and appear to be mediated via a transcriptional mechanism(s).
ontogenic regulation; renal biotin uptake; intestinal biotin uptake
This article has been cited by other articles:
|
|
 |
|
  V. S. Subramanian, J. S. Marchant, M. J. Boulware, T. Y. Ma, and H. M. Said Membrane targeting and intracellular trafficking of the human sodium-dependent multivitamin transporter in polarized epithelial cells Am J Physiol Cell Physiol, April 1, 2009; 296(4): C663 - C671. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Nabokina, M. L. Kashyap, and H. M. Said Mechanism and regulation of human intestinal niacin uptake Am J Physiol Cell Physiol, July 1, 2005; 289(1): C97 - C103. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. Reidling and H. M. Said Adaptive regulation of intestinal thiamin uptake: molecular mechanism using wild-type and transgenic mice carrying hTHTR-1 and -2 promoters Am J Physiol Gastrointest Liver Physiol, June 1, 2005; 288(6): G1127 - G1134. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Balamurugan, N. D. Vaziri, and H. M. Said Biotin uptake by human proximal tubular epithelial cells: cellular and molecular aspects Am J Physiol Renal Physiol, April 1, 2005; 288(4): F823 - F831. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Balamurugan and H. M. Said Ontogenic regulation of folate transport across rat jejunal brush-border membrane Am J Physiol Gastrointest Liver Physiol, November 1, 2003; 285(5): G1068 - G1073. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Balamurugan, A. Ortiz, and H. M. Said Biotin uptake by human intestinal and liver epithelial cells: role of the SMVT system Am J Physiol Gastrointest Liver Physiol, June 9, 2003; 285(1): G73 - G77. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
