Bartles J R, Zhang L Q, Verheyen E M, Hospodar K S, Nehme C L, Fayos B E
Department of Cell, Molecular and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
Dev Biol. 1991 Feb;143(2):258-70. doi: 10.1016/0012-1606(91)90076-f.
Antibodies were used to quantify seven domain-specific integral proteins of the rat hepatocyte plasma membrane during rat liver regeneration in response to two-thirds hepatectomy. Quantitative immunoblotting revealed that a subset of the plasma membrane proteins exhibited transient 30-70% decreases in relative concentration during the period of hepatocyte proliferation. The list of affected proteins included at least one representative from each of the plasma membrane domains: the apical protein HA 4, the lateral protein HA 321, and the basolateral receptors for epidermal growth factor and asialoglycoproteins. In contrast, the relative concentrations of three other plasma membrane proteins, the basolateral protein CE 9 and the two apical proteins dipeptidylpeptidase IV and aminopeptidase N, remained unchanged throughout liver regeneration. The decreases in the relative concentrations of the plasma membrane proteins were observed even when the synthesis of hepatocyte DNA was blocked by hydroxyurea, suggesting that the signalling for these two delayed consequences of two-thirds hepatectomy occurred along parallel, dependent pathways. Pulse and pulse-chase metabolic radiolabeling studies revealed that the decreases in the concentrations of the PM proteins were accomplished through protein-selective decreases in the rates of synthesis of the high-mannose precursors of the affected proteins, but not through the accelerated degradation of the mature plasma membrane proteins.
利用抗体对三分之二肝切除术后大鼠肝脏再生过程中大鼠肝细胞膜的七种结构域特异性整合蛋白进行定量分析。定量免疫印迹显示，在肝细胞增殖期间，一部分质膜蛋白的相对浓度出现了30%-70%的短暂下降。受影响的蛋白质列表包括来自每个质膜结构域的至少一个代表：顶端蛋白HA 4、侧面蛋白HA 321以及表皮生长因子和去唾液酸糖蛋白的基底外侧受体。相比之下，其他三种质膜蛋白，即基底外侧蛋白CE 9以及两种顶端蛋白二肽基肽酶IV和氨肽酶N的相对浓度在整个肝脏再生过程中保持不变。即使肝细胞DNA的合成被羟基脲阻断，也观察到质膜蛋白相对浓度的下降，这表明三分之二肝切除术后这两个延迟后果的信号传导是沿着平行的、相互依赖的途径发生的。脉冲和脉冲追踪代谢放射性标记研究表明，质膜蛋白浓度的下降是通过受影响蛋白的高甘露糖前体合成速率的蛋白质选择性降低实现的，而不是通过成熟质膜蛋白的加速降解实现的。
