TY - JOUR
T1 - Metabolites and analogs of 1α,25-dihydroxyvitamin D3
T2 - evaluation of actions in bone
AU - Kadiyala, Sudha
AU - Nagaba, Shizuka
AU - Takeuchi, Kazuhiro
AU - Yukihiro, Shigefume
AU - Qiu, Weiping
AU - Eyes, Sharon T.
AU - Uskokovic, Milan R.
AU - Posner, Gary H.
AU - Reddy, G. Satyanarayana
AU - Guggino, Sandra E.
N1 - Funding Information:
This work was funded by NIH DK43423 to S.E. Guggino. Some of the data presented here are published in [19,28] and are used with permission from the publishers. We wish to thank Steve Leung for his assistance.
PY - 2001/5/1
Y1 - 2001/5/1
N2 - Analogs of 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] activate both genomic mechanisms via the nuclear vitamin D3 receptor (nVDR) and nongenomic pathways via the plasma membrane vitamin D3 receptor (pmVDR). Both of these pathways are normally activated by 1α,25(OH)2D3, but as a result of synthesis of numerous analogs of 1α,25(OH)2D3 these pathways can be distinguished. We used increasing doses of vitamin D3 analogs to determine their potencies of action on these two distinct pathways, measuring calcium channel potentiation as an indicator of the nongenomic action and measuring increases in osteocalcin mRNA and protein release and bone resorption as indicators of genomic action. We found that both 25(OH)-16,23E-diene-D3 (R) and 1α,25(OH)2-16,23E-diene-D3 (A) are 10-fold more potent than 1α,25(OH)2D3 for activation of the nongenomic pathway because double bonds in the side chain and the D ring increase the affinity for calcium channel potentiation. While the C-1α-hydroxyl group is not necessary for potentiation of calcium channels, methyl groups at this position can alter the affinity for calcium channel potentiation. On the other hand, 1000 fold higher concentrations of nongenomic analogs were needed compared to 1α,25(OH)2D3 to increase osteocalcin mRNA or protein release. 1α,25-Dihydroxy-16-ene-23-yne-26,27-hexafluorovitamin D3, (E) is an agent that is 10 fold more potent than 1α,25(OH)2D3 at increasing osteocalcin mRNA and protein release, whereas 1α,25(OH)2-3-epi-D3 increases osteocalcin mRNA and protein with a potency over 10 fold lower than 1α,25(OH)2D3. These results suggest that double bonds in the side chain and the D ring stabilize action on the nongenomic pathway whereas F6 on the terminal portion of the side chain increases potency for nVDR. On the other hand, while the C-1α-hydroxyl group is necessary for activation of genomic events via nVDR, the activation of nongenomic events occurs in the absence of this group.
AB - Analogs of 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] activate both genomic mechanisms via the nuclear vitamin D3 receptor (nVDR) and nongenomic pathways via the plasma membrane vitamin D3 receptor (pmVDR). Both of these pathways are normally activated by 1α,25(OH)2D3, but as a result of synthesis of numerous analogs of 1α,25(OH)2D3 these pathways can be distinguished. We used increasing doses of vitamin D3 analogs to determine their potencies of action on these two distinct pathways, measuring calcium channel potentiation as an indicator of the nongenomic action and measuring increases in osteocalcin mRNA and protein release and bone resorption as indicators of genomic action. We found that both 25(OH)-16,23E-diene-D3 (R) and 1α,25(OH)2-16,23E-diene-D3 (A) are 10-fold more potent than 1α,25(OH)2D3 for activation of the nongenomic pathway because double bonds in the side chain and the D ring increase the affinity for calcium channel potentiation. While the C-1α-hydroxyl group is not necessary for potentiation of calcium channels, methyl groups at this position can alter the affinity for calcium channel potentiation. On the other hand, 1000 fold higher concentrations of nongenomic analogs were needed compared to 1α,25(OH)2D3 to increase osteocalcin mRNA or protein release. 1α,25-Dihydroxy-16-ene-23-yne-26,27-hexafluorovitamin D3, (E) is an agent that is 10 fold more potent than 1α,25(OH)2D3 at increasing osteocalcin mRNA and protein release, whereas 1α,25(OH)2-3-epi-D3 increases osteocalcin mRNA and protein with a potency over 10 fold lower than 1α,25(OH)2D3. These results suggest that double bonds in the side chain and the D ring stabilize action on the nongenomic pathway whereas F6 on the terminal portion of the side chain increases potency for nVDR. On the other hand, while the C-1α-hydroxyl group is necessary for activation of genomic events via nVDR, the activation of nongenomic events occurs in the absence of this group.
KW - 1α,25(OH)D
KW - Bone resorption
KW - Calcium channels
KW - Osteocalcin
KW - Osteosarcoma cells
UR - http://www.scopus.com/inward/record.url?scp=0035342697&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035342697&partnerID=8YFLogxK
U2 - 10.1016/S0039-128X(00)00167-7
DO - 10.1016/S0039-128X(00)00167-7
M3 - Article
C2 - 11179743
AN - SCOPUS:0035342697
SN - 0039-128X
VL - 66
SP - 347
EP - 355
JO - Steroids
JF - Steroids
IS - 3-5
ER -