Yj. Jeng et al., IDENTIFICATION OF VITAMIN-D-STIMULATED ALKALINE-PHOSPHATASE IN IEC-6 CELLS, A RAT SMALL-INTESTINE CRYPT CELL-LINE, Experimental cell research, 212(2), 1994, pp. 338-343
The IEC-6 cell line was derived from newborn rat small intestinal cryp
ts and maintains characteristics of nontransformed crypt epithelial ce
lls. We have reported that alkaline phosphatase (ALP) activity, a diff
erentiation marker for intestinal epithelial cells, is regulated in IE
C-6 cells by 1,25-dihydroxycholecalciferol (1,25(OH)(2)D-3). Using rev
erse transcription polymerase chain reaction, we determined that the A
LP in IEC-6 cells is the liver/bone/kidney ALP (LALP) isoenzyme and no
t the mature enterocyte form. Levamisole, a specific blocker for LALP,
blocked the ALP activity of IEC-6 cells. Kinetic studies showed that
1,25(OH)(2)D-3 increases V-m values of ALP in IEC-6 cells while K-m va
lues remain the same. Northern analysis of LALP mRNA levels in IEC-6 c
ells indicated that 10(-7) M 1,25(OH)(2)D-3 acts by increasing alkalin
e phosphatase activity at the gene expression level. (C) 1994 Academic
Press, Inc.