Expression and localization of intestine-derived faty acid-binding proteins in the rat

脂肪酸结合蛋白（fatty -binding protein， FABP）一种在哺乳动物组织中表达的与脂肪酸有高亲和力的同源低分子量细胞质蛋白家族，称为脂肪酸结合蛋白（fatty -binding protein， FABP）。已知大鼠小肠表达几种不同的FABPs，包括新发现的肠15kda蛋白（1-15P）。我们研究了I-15P在整个大鼠体内的表达和定位，采用免疫细胞化学定位蛋白，原位杂交定位mRNA。这两种技术都证实了I-15P在回肠肠细胞、卵巢黄体细胞和肾上腺类固醇内分泌细胞亚群中的表达。免疫电镜进一步证实，I-15P定位于上述细胞的细胞质区和核基质区。这些结果表明，I-15P不仅参与回肠上皮对胆盐的转运，还参与某些类固醇激素的代谢。接下来，在发育中的大鼠和促性腺激素诱导排卵的大鼠中，研究了两种类型的FABP，即I-15P和心脏FABP （H-FABP）的免疫组织化学定位。在出生后的卵巢发育过程中，i - 15p免疫反应性从2周到4周暂时局限于一小部分卵膜/间质细胞中，然后从5周开始出现在黄体细胞中，与周期的开始一致，直到成年。妊娠母马血清促性腺激素和人绒毛膜促性腺激素诱导未成熟（3周龄）卵巢排卵时，i - 15p免疫反应首先出现在大卵泡促黄体颗粒细胞中。相比之下，h - fabp免疫反应性在最初2周内暂时存在于滤泡上皮（颗粒）细胞中，此后在产后2周至成年期的卵泡/间质细胞中存在。这些结果表明，两种类型的FABPs在大鼠卵巢不同的类固醇细胞群中表达

A family of homologous, low-molecular-weight cytosolic proteins with high affinity for fatty acidsis expressed in mammalian tissues and called fatty acid-binding protein (FABP). Rat small intestine is knownto express several distinct FABPs, including newly-discovered intestinal 15 kDa protein (1-15P). We studied the expresion and localization of I-15P in the entire rat body, using the immunocytochemistry to localize protein and in situ hybridization to localize mRNA.Both techniques demonstrated the expression of I-15P in the enterocytes of ileum, luteal cells of ovary and a subpopulation of steroid-endocrine cells of adrenal gland. Immuno-electron microscopy further demonstrated that I-15P is localized in both the cytoplasmic and nuclear matrix regions of above cells. These results suggested the roles of I-15P not only in the transport of bile salts by ileal epithelium but also in the metabolisms of certain steroid hormones. Next, the immuohistohemical localizations of two types of FABPs, i.e., I-15P and heart FABP (H-FABP), were examined in the developing rat overies and in the rat overies induced to ovulate by gonadotropins. In the postnatal development of ovary, I-15P-immunoreactivity was localized temporarilyin a small subpopulation of theca/interstitial cells from 2 weeks to 4 weeks and then in the luteal cells from 5 weeks, in coincidence with the onset of cycles, into adulthood. In the immature (3 week old) ovaries inducedto ovulate by treatment with pregnant mare serum gonadotropin and human chorionic gonadotropin, I-15P-immunoreactivity first appeard in the luteinizing granulosa cells of large preovulatory follicles. In contrast, H-FABP-immunoreactivity was present temporarily in the follicular epithelial (granulosa) cells during the initial 2 weeks and thereafter in the theca/interstitial cells from 2 weeks postpartum into adulthood. These results suggested that two types of FABPs are expressed in distinct steroid cell populations of rat ovary, implecatin