Miller E K, Word R A, Goodall C A, Iacopino A M
Department of Biomedical Sciences, Baylor College of Dentistry, Dallas, Texas 75246.
J Clin Endocrinol Metab. 1994 Aug;79(2):609-15. doi: 10.1210/jcem.79.2.8045984.
The 9-kilodalton vitamin D-dependent calcium-binding protein (CaBP9K) is expressed in the intestine and uterus of mammals. In this study, we demonstrated the intracellular location of CaBP9K and quantified its expression in human myometrial tissues from nonpregnant and pregnant women (before and after the onset of labor). By Western blot analysis, we found that antiserum raised against bovine intestinal CaBP9K was specific for CaBP9K in human myometrium. By Northern blot analysis, with an oligodeoxynucleotide probe specific for human CaBP9K, we identified a single 0.7-kilobase messenger ribonucleic acid (mRNA) species in myometrial tissues from pregnant women before and after the onset of labor. CaBP9K mRNA and immunoreactive protein were localized within myometrial smooth muscle cells by in situ hybridization and immunohistochemistry. The highest levels of CaBP9K mRNA and immunoreactive protein were found in myometrial tissues obtained from pregnant women at term before the onset of labor. CaBP9K mRNA and immunoreactive levels of CaBP9K were decreased significantly in myometrial tissues obtained after the onset of labor (2- and 8-fold, respectively). These findings demonstrated for the first time that CaBP9K was present in human myometrium and suggested that it may play a role in regulating uterine smooth muscle function during pregnancy.
9千道尔顿的维生素D依赖性钙结合蛋白（CaBP9K）在哺乳动物的肠道和子宫中表达。在本研究中，我们证实了CaBP9K在细胞内的定位，并对非孕妇和孕妇（分娩前后）的人子宫肌层组织中其表达进行了定量。通过蛋白质免疫印迹分析，我们发现针对牛肠道CaBP9K产生的抗血清对人子宫肌层中的CaBP9K具有特异性。通过Northern印迹分析，使用针对人CaBP9K的寡脱氧核苷酸探针，我们在分娩前后孕妇的子宫肌层组织中鉴定出一种单一的0.7千碱基信使核糖核酸（mRNA）。通过原位杂交和免疫组织化学，CaBP9K mRNA和免疫反应性蛋白定位于子宫肌层平滑肌细胞内。在分娩前足月孕妇的子宫肌层组织中发现CaBP9K mRNA和免疫反应性蛋白的水平最高。分娩后获得的子宫肌层组织中CaBP9K mRNA和CaBP9K的免疫反应水平显著降低（分别降低2倍和8倍）。这些发现首次证明CaBP9K存在于人子宫肌层中，并表明它可能在妊娠期间调节子宫平滑肌功能中发挥作用。
