Regulation of secretion of parathormone and secretory protein-I from separate intracellular pools by calcium, dibutyryl cyclic AMP, and (1)- isoproterenol
Regulation of secretion of parathormone and secretory protein-I from separate intracellular pools by calcium, dibutyryl cyclic AMP, and (1)- isoproterenol
复制标题
钙、二丁酰环 AMP 和 (1)- 异丙肾上腺素对不同细胞内池中甲状旁腺素和分泌蛋白-I 分泌的调节
作者：
J. Morrissey;D. V. Cohn
分散的猪甲状旁腺细胞在3 H-或14 C-氨基酸的存在下，在0.5和3.0 mM之间的钙浓度下孵育，以标记新合成的甲状旁腺素。在较低的钙浓度下，分泌的激素高达4倍，但其比放射性（细胞内池的30至50倍）没有变化。在每个钙浓度下，二丁酰环磷酸腺苷使免疫活性甲状旁腺激素的分泌增加一倍，但如果同时加入标记氨基酸和促分泌素，放射性激素的分泌不会增加。同样，当甲状旁腺激素的细胞内池预先标记的3 H-氨基酸，然后细胞孵育14 C-氨基酸和二丁酰环AMP，激素分泌的整个增加来自预标记池。（1）-异丙肾上腺素增加细胞内的环腺苷酸，并以与双丁酰环腺苷酸无区别的方式作用于激素分泌。在类似的双标记实验中，二丁酰环腺苷酸优先增强分泌蛋白-I的分泌，这是一种功能未知的甲状旁腺钙调节蛋白。单独的钙以浓度依赖性方式抑制细胞内环磷酸腺苷水平。这些数据与甲状旁腺细胞制剂中存在的两种激素和分泌蛋白池一致，这两种蛋白池可能是单独可招募的-一种由最近合成的蛋白组成，另一种由较老的“储存”蛋白组成。这些数据不允许人们决定这两个池是否在单个细胞内共存，或者它们是否存在于分散的腺体制备物的单独细胞中。
Dispersed porcine parathyroid cells were incubated at calcium concentrations between 0.5 and 3.0 mM in the presence of 3H- or 14C- amino acids to label newly synthesized parathormone. Up to four times more hormone was secreted at the lower calcium concentration but its specific radioactivity, from 30 to 50 times that of the intracellular pool, did not change. Dibutyrl cyclic AMP doubled immunoactive parathormone secretion at each calcium concentration, but there was no increase in secretion of radioactive hormone if labeled amino acids and secretagogue were added simultaneously. Similarly, when the intracellular pool of parathormone was prelabeled with 3H-amino acids and then the cells were incubated in 14C-amino acids and dibutyryl cyclic AMP, the entire increase in hormone secreted was derived from the prelabeled pool. (1)-isoproterenol increased intracellular cyclic AMP and acted on hormone secretion in a manner indistinguishable from dibutyryl cyclic AMP. In similar double-label experiments dibutyryl cyclic AMP preferentially enhanced secretion of secretory protein-I, a calcium-regulated protein of the parathyroid of unknown function. Calcium, alone, inhibited the intracellular level of cyclic AMP in a concentration-dependent fashion. These data are consistent with the existence in the parathyroid cell preparation of two hormone and secretory protein pools that may be individually recruitable--one consisting of most recently synthesized protein, the other consisting of older "storage" protein. The data do not allow one to decide whether the two pools coexist within individual cells or whether, instead, they exist in separate cells of the dispersed gland preparation.