THE TEAR FILM AND THE OCULAR SURFACE: VITAMIN A IN TEARS

维甲酸是由泪腺分泌的。建议进行的研究 将检验泪腺是一种特殊的 含有维甲酸受体的维生素A靶组织 蛋白质，视黄酸酯的合成和水解酶。 和视黄醇分泌到泪腺液的机制 (LGF)。建议在LGF中合成一种载体蛋白， 通过腺体，将视黄醇输送到眼睛的细胞 表面，作为这些细胞的维生素A来源。 具体目标： 1.视黄酸酯的储存、合成和水解 泪腺的放射自显影和测量 酰辅酶A：视黄醇转移酶活性和视黄酯 水解酶活性。 2.研究维甲酸分泌的机制和调控 体外用分散的泪腺腺泡和培养细胞。 3.将确定LGF中的20kd蛋白是否 结合视黄醇是视黄醇结合蛋白基因的克隆 寻找这种蛋白质，并探测腺体中的RBP mRNA。 4.将测定细胞视黄醇和视黄酸 酸结合蛋白存在于泪腺中，通过探测 为它们的信使RNA提供腺体。 5.将确定眼泪是否是维生素的来源 A通过测量兔角膜中的维甲酸水平来检测角膜 泪液分泌正常或受损。 6.维甲酸在培养的角膜中的作用机制 将通过测量cAMP依赖蛋白来测试上皮细胞 激酶活性、层粘连蛋白合成和细胞黏附。 这些研究将有助于理解 泪膜异常与眼表疾病的关系。

Retinoids are secreted by the lacrimal gland. The proposed studies will test the hypothesis that the lacrimal gland is a specialized target tissue for Vitamin A which contains retinoid receptor proteins, enzymes for synthesis and hydrolysis of retinyl esters. and mechanisms for secretion of retinol into lacrimal gland fluid (LGF). It is proposed that a carrier protein in LGF, synthesized by the gland, transports retinol to the cells of the ocular surface, serving as a source of vitamin A for these cells. Specific Aims: 1. Storage, synthesis, and hydrolysis of retinyl esters in the lacrimal gland will be studied by radioautography and measurement of acyl-CoA:retinol transferase activity and retinyl ester hydrolase activity. 2. Mechanisms and control of retinoid secretion will be studied in vitro using dispersed lacrimal gland acini and cultured cells. 3. It will be determined whether a 20-kd protein in LGF which binds retinol is retinol binding protein (RBP) by cloning the cDNA for this protein and probing the gland for RBP mRNA. 4. It will be determined whether cellular retinol and retinoic acid binding proteins are present in lacrimal gland by probing the gland for their messenger RNAs. 5. It will be determined whether the tears are a source of vitamin A for the cornea by measuring retinoid levels in corneas of rabbits with normal or impaired tear secretion. 6. Mechanisms of action of retinoids in the cultured corneal epithelial cells will be tested by measuring cAMP-dependent Protein kinase activity, laminin synthesis, and cell adhesion. These studies will contribute to the understanding of the relationship of tear film abnormalities to ocular surface disease.