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，在生长和发育中尤其重要，并且对于体内产生的各种化合物的生物活性和解毒也是如此。 硫酸化蛋白聚糖是哺乳动物细胞膜和组织的组分，并且是细胞分化所必需的细胞识别系统的一部分。 血清硫酸盐浓度在妊娠期增加，胎儿和幼儿的浓度高于成人，这与生长和发育期间对该阴离子的生理需求增加一致。 容量限制性肾重吸收在无机硫酸盐血浆浓度的调节中具有首要重要性。 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是不可用的。 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。 这两个工具是必不可少的，以评估硫酸盐重吸收的生理调节。 因此，Morris博士将（1）开发定量硫酸盐阴离子交换蛋白（sat-1）mRNA的方法，（2）制备抗体以测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，和（3）开发豚鼠近端小管细胞的原代细胞培养系统，并表征这些培养细胞中硫酸盐和其它内源性底物的摄取。

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.