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

脂肪酸结合蛋白（FABP）是一个在哺乳动物组织中表达的对脂肪酸具有高亲和力的同源、低分子量胞质蛋白家族。已知大鼠小肠表达几种不同的FABP，包括新发现的肠15 kDa蛋白（1- 15 P）。用免疫细胞化学和原位杂交技术分别对大鼠全身I-15 P的表达和定位进行了研究，结果表明I-15 P在回肠肠上皮细胞、卵巢黄体细胞和肾上腺类固醇内分泌细胞中均有表达。免疫电镜进一步证实I-15 P定位于上述细胞的胞质和核基质区。这些结果表明，I-15 P不仅在回肠上皮转运胆盐，而且在某些类固醇激素的代谢中的作用。其次，两种类型的FABP的免疫组织化学定位，本文对发育期和促性腺激素诱导排卵期大鼠卵巢进行了I-15 P和心脏FABP（H-FABP）的测定。在出生后的卵巢发育中，I-15 P免疫反应性暂时定位于卵泡膜/间质细胞的一个小的亚群，从2周到4周，然后在黄体细胞从5周，在符合周期的开始，到成年。在孕马血清促性腺激素和人绒毛膜促性腺激素诱导排卵的未成熟（3周龄）卵巢中，I-15 P免疫反应首先出现在排卵前大卵泡的黄体化颗粒细胞中。与此相反，H-FABP免疫反应暂时存在于滤泡上皮（颗粒）细胞在最初的2周，此后在卵泡膜/间质细胞从产后2周到成年。这些结果表明，两种类型的FABPs表达在不同的类固醇细胞群，implectin

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