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体内平衡的调节。无机硫酸盐是生物合成反应所必需的生理离子，在生长发育中尤其重要，对体内产生的各种化合物的生物活性和解毒也很重要。硫酸化蛋白聚糖是哺乳动物细胞膜和组织的组成部分，是细胞分化所必需的细胞识别系统的一部分。妊娠期血清硫酸根浓度升高，胎儿和幼儿的硫酸根浓度高于成人，这与生长发育过程中对硫酸根阴离子的生理需求增加一致。肾重吸收能力受限是调节血浆无机硫酸盐浓度的主要因素。这些肾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必需的抗体是不可用的。同样，没有可用的细胞系表现出与在分离的肾皮质制剂中观察到的相似的硫酸盐转运特征。这两个工具是必不可少的，以评估硫酸盐再吸收的生理调节。因此，Morris博士将(1)开发硫酸盐阴离子交换蛋白（sat-1） mRNA的定量方法，(2)产生抗体来测定肾刷状边界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。(3)建立豚鼠近端小管细胞的原代培养系统，并表征这些培养细胞对硫酸盐和其他内源性底物的摄取。

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.