Bastani B, Yang L, Baldassare J J, Pollo D A, Gardner J D
Division of Nephrology, Saint Louis University Health Sciences Center, MO 63104, USA.
Biochim Biophys Acta. 1995 Nov 30;1269(3):307-15. doi: 10.1016/0167-4889(95)00120-0.
As in a previous study (Biochim, Biophys. Acta 1224 (1994) 127-138), we used quantitative immunoblot analysis and found that rat pancreatic acini possess four different isoforms of PKC-alpha, delta, epsilon and zeta. The phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) caused translocation of each isoform from the cytosol to the membrane fraction. CCK-8 increased diacylglycerol (DAG) and caused translocation of PKC-sigma and PKC-epsilon but not that of PKC-alpha or PKC-zeta. L-364,718, a CCK receptor antagonist, prevented as well as reversed the effects of CCK-8 on DAG and on translocation of PKC-sigma and PKC-epsilon. To explore the possibility that different isoforms of PKC might have different distributions in rat pancreas, we used immunocytochemistry to determine the cellular distribution of different isoforms of PKC in intact pancreas as well as pancreatic acini. In intact pancreas, PKC-alpha and PKC-sigma were detected in islet cells but not in duct or acinar cells. PKC-epsilon was detected in the apical region of acinar cells and PKC-zeta was detected over the luminal surfaces of acinar cells and the ductules that extend from the acinus. Neither PKC-epsilon nor PKC-zeta was detected in islets. In pancreatic acini PKC-alpha and PKC-sigma were detected in islets or fragments of islets that contaminated the preparation but were not detected in acinar cells. PKC-epsilon was detected in the apical region of acinar cells and adding 1 microM TPA or 1 microM CCK-8 accentuated the immunostaining but did not alter its cellular distribution. L-364,718 reversed the changes in immunostaining caused by CCK-8. PKC-zeta was detected over the luminal surface of the acinar cells. TPA, but not CCK-8 or CCK-8 followed by L-364,718, increased the number of acini that showed staining of the luminal surfaces of acinar cells. Thus, the present results demonstrate that different isoforms of PKC are distributed differently in rat pancreas and that the different patterns of distribution can explain, at least in part, the different responses to CCK-8.
正如之前的一项研究（《生物化学与生物物理学报》1224卷（1994年）127 - 138页）所示，我们采用定量免疫印迹分析发现，大鼠胰腺腺泡细胞拥有蛋白激酶C（PKC）的四种不同亚型，即α、δ、ε和ζ亚型。佛波酯12 - O - 十四酰佛波醇13 - 乙酸酯（TPA）致使每种亚型从胞质溶胶转位至膜组分。胆囊收缩素八肽（CCK - 8）增加了二酰甘油（DAG）的含量，并引起PKC - σ和PKC - ε的转位，但未引起PKC - α或PKC - ζ的转位。CCK受体拮抗剂L - 364,718既能预防也能逆转CCK - 8对DAG以及PKC - σ和PKC - ε转位的影响。为探究PKC不同亚型在大鼠胰腺中可能具有不同分布的可能性，我们运用免疫细胞化学方法来确定PKC不同亚型在完整胰腺以及胰腺腺泡细胞中的细胞分布。在完整胰腺中，PKC - α和PKC - σ在胰岛细胞中被检测到，但在导管或腺泡细胞中未被检测到。PKC - ε在腺泡细胞的顶端区域被检测到，PKC - ζ在腺泡细胞的管腔表面以及从腺泡延伸出的小导管上被检测到。在胰岛中未检测到PKC - ε和PKC - ζ。在胰腺腺泡中，PKC - α和PKC - σ在污染制剂的胰岛或胰岛片段中被检测到，但在腺泡细胞中未被检测到。PKC - ε在腺泡细胞的顶端区域被检测到，添加1微摩尔TPA或1微摩尔CCK - 8可增强免疫染色，但不改变其细胞分布。L - 364,718逆转了由CCK - 8引起的免疫染色变化。PKC - ζ在腺泡细胞的管腔表面被检测到。TPA增加了显示腺泡细胞管腔表面染色的腺泡数量，而CCK - 8或CCK - 8加L - 364,718则未产生此效果。因此，目前的结果表明，PKC的不同亚型在大鼠胰腺中的分布不同，并且至少在一定程度上，这种不同的分布模式可以解释对CCK - 8的不同反应。
