Study on the physiological role of intestinal cellular retinol-binding protein, type II

我们研究了细胞视黄醇结合蛋白II（CRBP（II））的生理作用，并获得了以下结果。(1)我们从鸡肠（17 kDa）和大鼠肠（16 kDa）中纯化了CRBP（II）。利用制备的CRBP（Ⅱ）抗血清，建立了CRBP（Ⅱ）的酶联免疫吸附试验（ELISA）。鸡CRBP（II）对视黄醇和视黄醛均具有结合特异性。(2)在鸡肠道围产期发育过程中，CRBP（II）水平从胚胎发育的第20天到孵化后1天升高了10倍。(3)CRBP（II）在鸡的十二指肠和空肠（尤其是绒毛中段）中表达量较高，而在回肠中表达量较低。(4)CRBP（II）在孵化期前后也在肝脏中表达，但5日龄后表达水平很低。暂时出现的肝脏CRBP（II）可能在肝脏β-胡萝卜素代谢中起一定作用，因为肠腔β-胡萝卜素含量、血清 ...更多信息 β-胡萝卜素浓度和肝视网膜还原酶活性在围产期都升高。(5)由于肠道CRBP（II）将吸收的视黄醇引导至卵磷脂：视黄醇酰基转移酶（LRAT），我们测量了接受手术或饮食操作的动物小肠中的CRBP（II）和LRAT活性。空肠转流术组大鼠剩余空肠段CRBP（II）水平升高。肠道LRAT活性增强与CRBP（II）的增加平行孵化期的鸡，和CRBP（II）和LRAT活性降低喂养维生素A耗尽的饮食。饲喂蛋白质营养不良的饮食导致LRAT活性降低，但不CRBP（II）的含量，在空肠。(6)以鸡小肠mRNA为模板，制备了CRBP（II）cDNA探针，证明了在鸡十二指肠和肝脏中，CRBP（II）mRNA在CRBP（II）蛋白出现前不久就已表达，提示了CRBP（II）在围产期的转录调控。少

We investigated the physiological roles of cellular retinol-binding protein, type II (CRBP(II)) and obtained the following results.(1) We purified CRBP(II) from chicken intestine (17 kDa) and rat intestine (16 kDa). Using the antisera prepared against CRBP(II), we developed enzyme-linked immunosorbent assay (ELISA) system for CRBP(II). Chicken CRBP(II) showed the binding specificities to both retinol and retinal.(2) During perinatal development of chicken intestine, CRBP(II) level was elevated by 10 fold from Day 20 of embryogenesis to 1 day after hatching.(3) CRBP(II) was highly expressed in duodenum and jejunum (especially in the mid-villus region) of chicken, but the level was low in the ileum.(4) CRBP(II) was also expressed in the liver around the hatching period of chicken, but the level was very low after 5 days of age. The temporarily appearing hepatic CRBP(II) might play some role in beta-carotene metabolism in the liver, because intestinal luminal beta-carotene content, serum … More beta-carotene concentration, and hepatic retinal reductase activity were all elevated during the perinatal period.(5) Since intestinal CRBP(II) directs absorbed retinol to lecithin:retinol acyltransferase (LRAT), we measured both CRBP(II) and LRAT activity in the small intestine of animals subjected to surgery or dietary manipulations. The rats subjected to jejunum-bypass operation showed elevated level of CRBP(II) in the remaining jejunal segment. Intestinal LRAT activity was enhanced in parallel with the increase in CRBP(II) around the hatching period of chicken, and both CRBP(II) and LRAT activity were reduced by feeding vitamin A-depleted diet. Feeding rats the protein malnourished diets led to reduction in LRAT activity, but not CRBP(II) contents, in jejunum.(6) We prepared CRBP(II)cDNA probe using chicken intestinal mRNA's as a template, and demonstrated that CRBP(II)mRNA was expressed shortly before the appearance of CRBP(II) proteins in duodenum and liver of chicken, suggesting the transcriptional regulation of CRBP(II) in this perinatal period. Less