Calbindin-D9k mRNA is tightly regulated during the estrous cycle in the rat uterus.
Calbindin-D9k (CaBP-9k) is a cytosolic calcium binding protein with a molecular weight of 9000. CaBP-9k is mainly expressed in intestine, uterus and placenta, with intestinal levels controlled by vitamin D and uterine levels controlled by estrogens. CaBP-9k mRNA levels were measured in rat uterus throughout the estrous cycle. On the morning of proestrus, estrus and diestrus animals were sacrificed. Serum 17 beta-estradiol concentrations were determined using a radioimmunoassay. Whole uterus was used for preparation of total RNA. Northern blot analysis was performed to quantify CaBP-9k and beta-actin mRNA. CaBP-9k levels were highest at proestrus, dropped 10-fold at estrus and were not detectable at diestrus. beta-Actin levels did not change significantly throughout the estrous cycle. Peak 17 beta-estradiol concentrations coincided with maximum CaBP-9k mRNA expression at proestrus. Despite minimal concentrations of 17 beta-estradiol at estrus, CaBP-9k mRNA was still present at 10% of the proestrus level. At diestrus, CaBP-9k mRNA was not detectable despite increasing 17 beta-estradiol. It is concluded that CaBP-9k is subject to 17 beta-estradiol regulation during the estrous cycle. Correlation between CaBP-9k mRNA and 17 beta-estradiol levels indicates a lag period for CaBP-9k induction in diestrus following a rise in steroid hormone levels.
Krisinger
J
J
Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, Canada.
Dann
J L
JL
Currie
W D
WD
Jeung
E B
EB
Leung
P C
PC
D000818:Animals; D064026:Calbindins; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis* / Q000235:genetics; D014599:Uterus / Q000378:metabolism*
D064026:Calbindins; D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G; C576508:S100g protein, rat; D004958:Estradiol