CONTROL OF CALBINDIN-D-28K EXPRESSION IN DEVELOPING MOUSE KIDNEY

Calbindin-D-28K, a cytoplasmic calcium-binding protein located in restricted regions of mature metanephric kidneys, is expressed in a complex manner by kidneys developing in culture. In developing collecting duct, it is present in all regions and is independent of 1,25-dihydroxy-vitamin D-3 [1,25(OH)(2)D-3]. In developing nephrons, its expression is restricted to the most distal end of the growing tubule, commences during differentiation of specialized tubule segments, and depends completely on the presence of 1,25(OH)(2)D-3. The Wolffian ducts of mesonephric kidneys also express calbindin independently of 1,25(OH)(2)D-3, as do the Wolffian duct-derived connecting tubules, but mesonephric nephrons show no expression of the molecule. By displaying separate tissue-specific controls for calbindin expression, cultured kidney rudiments offer a very accessible system for investigation of the control mechanisms involved. (C) 1994 Wiley-Liss, Inc.