Satoh Keitaro, Narita Takanori, Katsumata-Kato Osamu, Sugiya Hiroshi, Seo Yoshiteru
Department of Regulatory Physiology, Dokkyo Medical University School of Medicine, Tochigi, Japan;
Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Kanagawa, Japan;
Am J Physiol Gastrointest Liver Physiol. 2016 Mar 15;310(6):G399-409. doi: 10.1152/ajpgi.00198.2015. Epub 2016 Jan 7.
Cholecystokinin (CCK) is a gastrointestinal hormone that induces exocytotic amylase release in pancreatic acinar cells. The activation of protein kinase C (PKC) is involved in the CCK-induced pancreatic amylase release. Myristoylated alanine-rich C kinase substrate (MARCKS) is a ubiquitously expressed substrate of PKC. MARCKS has been implicated in membrane trafficking in several cell types. The phosphorylation of MARCKS by PKC results in the translocation of MARCKS from the membrane to the cytosol. Here, we studied the involvement of MARCKS in the CCK-induced amylase release in rat pancreatic acini. Employing Western blotting, we detected MARCKS protein in the rat pancreatic acini. CCK induced MARCKS phosphorylation. A PKC-δ inhibitor, rottlerin, inhibited the CCK-induced MARCKS phosphorylation and amylase release. In the translocation assay, we also observed CCK-induced PKC-δ activation. An immunohistochemistry study showed that CCK induced MARCKS translocation from the membrane to the cytosol. When acini were lysed by a detergent, Triton X-100, CCK partially induced displacement of the MARCKS from the GM1a-rich detergent-resistant membrane fractions (DRMs) in which Syntaxin2 is distributed. A MARCKS-related peptide inhibited the CCK-induced amylase release. These findings suggest that MARCKS phosphorylation by PKC-δ and then MARCKS translocation from the GM1a-rich DRMs to the cytosol are involved in the CCK-induced amylase release in pancreatic acinar cells.
胆囊收缩素（CCK）是一种胃肠激素，可诱导胰腺腺泡细胞通过胞吐作用释放淀粉酶。蛋白激酶C（PKC）的激活参与CCK诱导的胰腺淀粉酶释放。富含豆蔻酰化丙氨酸的C激酶底物（MARCKS）是PKC普遍表达的底物。MARCKS已被证明参与多种细胞类型的膜转运。PKC对MARCKS的磷酸化导致MARCKS从膜转移到细胞质。在此，我们研究了MARCKS在CCK诱导的大鼠胰腺腺泡淀粉酶释放中的作用。通过蛋白质印迹法，我们在大鼠胰腺腺泡中检测到MARCKS蛋白。CCK诱导MARCKS磷酸化。PKC-δ抑制剂rottlerin抑制CCK诱导的MARCKS磷酸化和淀粉酶释放。在转位试验中，我们还观察到CCK诱导的PKC-δ激活。免疫组织化学研究表明，CCK诱导MARCKS从膜转移到细胞质。当腺泡用去污剂Triton X-100裂解时，CCK部分诱导MARCKS从富含GM1a的抗去污剂膜组分（DRMs）中移位，Syntaxin2分布于其中。一种与MARCKS相关的肽抑制CCK诱导的淀粉酶释放。这些发现表明，PKC-δ介导的MARCKS磷酸化以及随后MARCKS从富含GM1a的DRMs转移到细胞质参与了CCK诱导的胰腺腺泡细胞淀粉酶释放。
