Leblond C P
Department of Anatomy, McGill University, Montreal, Quebec, Canada.
Anat Rec. 1989 Jun;224(2):123-38. doi: 10.1002/ar.1092240204.
The production of type I collagen by fibroblasts, odontoblasts, and osteoblasts is reviewed on the basis of results obtained by electron microscopy, 3H-proline radioautography, and immunostaining for type I procollagen. In the three cell types, the precursors of type I collagen are processed along the rough endoplasmic reticulum (rER)-Golgi-secretory granule pathway in the same manner as secretory proteins, but the available evidence suggests a few special features: 1) From the rER site of synthesis, the initial collagen precursors, known as pro-alpha chains, are transported to the Golgi apparatus within tubular structures, referred to as intermediate tubules, rather than within vesicles. 2) The pro-alpha chains coil into a triple helix within spherical distensions present along the saccules on the cis side of Golgi stacks. 3) The resulting procollagens are fairly rigid and form bundles that cause spherical distensions to lengthen into cylindrical ones, whereas by an unknown mechanism these distensions become part of the saccules on the trans-side of Golgi stacks. 4) The procollagen-containing cylindrical distensions are released from trans-saccules to become secretory granules, and some procollagen material finds its way into lysosomes. 5) The secretory granules release their procollagen content by exocytosis at the cell surface. 6) The released procollagen is transformed into collagen before or, more probably, after associating with the surface of a collagen fibril.
基于电子显微镜、³H-脯氨酸放射自显影以及I型前胶原免疫染色所获得的结果，对成纤维细胞、成牙本质细胞和成骨细胞产生I型胶原的过程进行了综述。在这三种细胞类型中，I型胶原的前体沿着粗面内质网（rER）-高尔基体-分泌颗粒途径进行加工，其方式与分泌蛋白相同，但现有证据表明存在一些特殊特征：1）从合成的rER位点开始，最初的胶原前体，即前α链，通过称为中间小管的管状结构运输到高尔基体，而不是通过囊泡运输。2）前α链在高尔基体堆叠顺面的囊泡上的球形扩张内盘绕成三螺旋结构。3）产生的前胶原相当坚硬并形成束状，导致球形扩张延伸为圆柱形，而通过未知机制，这些扩张成为高尔基体堆叠反面囊泡的一部分。4）含有前胶原的圆柱形扩张从反面囊泡释放成为分泌颗粒，一些前胶原物质进入溶酶体。5）分泌颗粒通过细胞表面的胞吐作用释放其前胶原内容物。6）释放的前胶原在与胶原纤维表面结合之前或更可能在结合之后转化为胶原。
