TY - JOUR
T1 - Vitamin A-sensitive tissues in transgenic mice expressing high levels of human cellular retinol-binding protein type I are not altered phenotypically
AU - Trøen, Gunhild
AU - Eskild, Winnie
AU - Fromm, Sigurd H.
AU - De Luca, Luigi M.
AU - Ong, David E.
AU - Wardlaw, Sarah A.
AU - Reppe, Sjur
AU - Blomhoff, Rune
PY - 1999
Y1 - 1999
N2 - The suggested function of cellular retinol-binding protein type I [CRBP(I)] is to carry retinol to esterifying or oxidizing enzymes. The retinyl esters are used in storage or transport, whereas oxidized forms such as all-trans or 9-cis retinoic acid are metabolites used in the mechanism of action of vitamin A. Thus, high expression of human CRBP(I) [hCRBP(I)] in transgenic mice might be expected to increase the production of retinoic acid in tissues, thereby inducing a phenotype resembling vitamin A toxicity. Alternatively, a vitamin A-deficient phenotype could also be envisioned as a result of an increased accumulation of vitamin A in storage cells induced by a high hCRBP(I) level. Signs of vitamin A toxicity or deficiency were therefore examined in tissues from transgenic mice with ectopic expression of hCRBP(I). TeStis and intestine, the tissues with the highest expression of the transgene, showed normal gross morphology. Similarly, no abnormalities were observed in other tissues known to be sensitive to vitamin A status such as cornea and retina, and the epithelia in the cervix, trachea and skin. Furthermore, hematologic variables known to be influenced by vitamin A status such as the hemoglobin concentration, hematocrits and the number of red blood cells were within normal ranges in the transgenic mice. In conclusion, these transgenic mice have normal function of vitamin A despite high expression of hCRBP(I) in several tissues.
AB - The suggested function of cellular retinol-binding protein type I [CRBP(I)] is to carry retinol to esterifying or oxidizing enzymes. The retinyl esters are used in storage or transport, whereas oxidized forms such as all-trans or 9-cis retinoic acid are metabolites used in the mechanism of action of vitamin A. Thus, high expression of human CRBP(I) [hCRBP(I)] in transgenic mice might be expected to increase the production of retinoic acid in tissues, thereby inducing a phenotype resembling vitamin A toxicity. Alternatively, a vitamin A-deficient phenotype could also be envisioned as a result of an increased accumulation of vitamin A in storage cells induced by a high hCRBP(I) level. Signs of vitamin A toxicity or deficiency were therefore examined in tissues from transgenic mice with ectopic expression of hCRBP(I). TeStis and intestine, the tissues with the highest expression of the transgene, showed normal gross morphology. Similarly, no abnormalities were observed in other tissues known to be sensitive to vitamin A status such as cornea and retina, and the epithelia in the cervix, trachea and skin. Furthermore, hematologic variables known to be influenced by vitamin A status such as the hemoglobin concentration, hematocrits and the number of red blood cells were within normal ranges in the transgenic mice. In conclusion, these transgenic mice have normal function of vitamin A despite high expression of hCRBP(I) in several tissues.
KW - Cellular retinol-binding protein I
KW - Transgenic mice
KW - Vitamin A
UR - http://www.scopus.com/inward/record.url?scp=0032867205&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032867205&partnerID=8YFLogxK
U2 - 10.1093/jn/129.9.1621
DO - 10.1093/jn/129.9.1621
M3 - Article
C2 - 10460195
AN - SCOPUS:0032867205
SN - 0022-3166
VL - 129
SP - 1621
EP - 1627
JO - Journal of Nutrition
JF - Journal of Nutrition
IS - 9
ER -