Orci L, Ravazzola M, Amherdt M, Yanaihara C, Yanaihara N, Halban P, Renold A E, Perrelet A
J Cell Biol. 1984 Jan;98(1):222-8. doi: 10.1083/jcb.98.1.222.
We have obtained evidence by autoradiography and immunocytochemistry that mature secretory granules of the pancreatic B-cell gain access to a lysosomal compartment (multigranular or crinophagic bodies) where the secretory granule content is degraded. Whereas the mature secretory granule content shows both insulin and C-peptide (proinsulin) immunoreactivities, in crinophagic bodies only insulin, but not C-peptide, immunoreactivity was detectable. The absence of C-peptide (proinsulin) immunoreactivity in multigranular bodies, i.e., in early morphological stages of lysosomal digestion, was compatible with the ready access and breakdown of C-peptide and/or proinsulin by lysosomal degrading enzymes, while the insulin crystallized in secretory granule cores remained relatively protected. However, in the final stage of lysosomal digestion, i.e., in residual bodies where the secretory granule core material is no longer present, insulin immunoreactivity became undetectable. Lysosomal digestion thus appears to be a normal pathway for insulin degradation in the pancreatic B-cell.
我们通过放射自显影和免疫细胞化学获得证据，表明胰腺B细胞的成熟分泌颗粒进入溶酶体区室（多颗粒或嗜铬体），在那里分泌颗粒内容物被降解。成熟分泌颗粒内容物同时显示胰岛素和C肽（胰岛素原）免疫反应性，而在嗜铬体中仅可检测到胰岛素免疫反应性，未检测到C肽免疫反应性。在多颗粒体中，即在溶酶体消化的早期形态阶段，C肽（胰岛素原）免疫反应性的缺失与溶酶体降解酶对C肽和/或胰岛素原的快速作用和分解相一致，而分泌颗粒核心中结晶的胰岛素仍受到相对保护。然而，在溶酶体消化的最后阶段，即在不再存在分泌颗粒核心物质的残余体中，胰岛素免疫反应性变得无法检测到。因此，溶酶体消化似乎是胰腺B细胞中胰岛素降解的正常途径。
