Career Advancement Award: Physiological Regulation of Sulfate Homeostasis: Development of Techniques

莫里斯博士的长期研究目标是了解硫酸盐稳态的调节。 无机硫酸盐是生物合成反应所必需的生理离子，对于生长和发育以及体内产生的各种化合物的生物活性和解毒尤其重要。 硫酸化蛋白聚糖是哺乳动物细胞膜和组织的组成部分，也是细胞分化所需的细胞识别系统的一部分。 妊娠期间硫酸盐的血清浓度增加，胎儿和幼儿的硫酸盐浓度高于成人，这与生长和发育过程中对这种阴离子的生理需求增加一致。 容量限制的肾脏重吸收对于无机硫酸盐血浆浓度的调节至关重要。 这些肾脏转运改变的机制尚不清楚。 然而，评估两种肾硫酸盐转运蛋白的蛋白表达所需的抗体尚不可用。 同样，没有可用的细胞系表现出与分离的肾皮质制剂中观察到的特征相似的硫酸盐转运特征。 这两种工具对于评估硫酸盐重吸收的生理调节都是必不可少的。 因此，Morris 博士将 (1) 开发定量硫酸根阴离子交换蛋白 (sat-1) mRNA 的方法，(2) 产生抗体以确定肾刷状缘膜钠依赖性共转运蛋白 (NaSi-1) 和肾基底外侧膜阴离子交换转运蛋白 (sat-1) 的蛋白表达，并表征这些抗体的特异性，以及 (3) 开发豚鼠的原代细胞培养系统近端小管细胞并表征这些培养细胞中硫酸盐和其他内源底物的摄取。

Dr. Morris's long-term research goal is to understand the regulation of sulfate homeostasis. Inorganic sulfate is a physiological ion necessary for biosynthetic reactions especially important in growth and development, and for the biologic activity and detoxification of various compounds produced in the body. Sulfated proteoglycans are components of mammalian cell membranes and tissues, and are part of the cell-recognition system necessary for cell differentiation. Serum concentrations of sulfate increase in pregnancy and are higher in fetuses and young children than in adults, consistent with an increased physiological requirement for this anion during growth and development. Capacity-limited renal reabsorption is of primary importance in the regulation of plasma concentrations of inorganic sulfate. The mechanism(s) underlying these alterations in renal transport is not known. However, the antibodies necessary to evaluate protein expression of the two renal sulfate-transport proteins are not available. As well, no available cell line exhibits sulfate transport with characteristics similar to those observed in isolated kidney-cortex preparations. Both of these tools are essential in order to evaluate the physiological regulation of sulfate reabsorption. Therefore, Dr. Morris will (1) develop methods to quantitate mRNA for the sulfate anion-exchange protein (sat-1), (2) produce antibodies to determine protein expression for the renal brush-border membrane sodium-dependent cotransport protein (NaSi-1) and the renal basolateral membrane anion-exchange transport protein (sat-1) and to characterize the specificity of these antibodies, and (3) develop a primary cell-culture system of guinea-pig proximal-tubule cells and to characterize the uptake of sulfate and other endogenous substrates in these cultured cells.