Effects of L‐azetidine‐2‐carboxylic acid on matrix secretion and Golgi structure in fibroblasts and osteoblasts of the mouse

Abstract

The effect of a proline analogue, L-azetidine-2-carboxylic acid (LACA), on collagenous matrix secretion by periodontal ligament fibroblasts and alveolar bone osteoblasts was studied by light and electron microscopic radioautography after injection of 3H-glycine; 3H-glycine labeled material accumulated in the cisternae of the rough endoplasmic reticulum and was not secreted for over 4 hours. The Golgi complex of both fibroblasts and osteoblasts showed a marked alteration of its composition after LACA administration. All Golgi saccules and collagen secretion granules disappeared within 2 hours. Flattened Golgi cisternae were still present and appeared to be unaffected by the administration of LACA. These observations indicate that Golgi saccules in collagen-secreting cells are the initial staging areas for the formation of collagen secretory granules and that there is a close correlation between form and function in the Golgi apparatus of collagen-secreting cells.

The Golgi ribbon structure facilitates anterograde transport of large cargoes

“…Finally, mammalian cells secrete numerous fibril-forming collagen species that extensively aggregate within the cell, and it is these cells that display an extensive Golgi ribbon. “Professional” collagen/matrix-secreting cells, such as fibroblasts and osteoblasts, often contain a single elongated Golgi ribbon ( Cho and Garant, 1985 ). These correlations broadly match the expectations of rim progression.…”

Extracellular matrix synthesis is required for the movement of sclerotome and neural crest cells on collagen

“…As proline analogs, cis-HP and LACA are well established as agents that inhibit the secretion and deposition of triple helical procollagen from cells [4, 16, 271. However, although the primary biochemical targets of these drugs is in the collagen biosynthetic pathway, it must be emphasized that effects due to perturbation of interlinked processes cannot be entirely eliminated. Both cis-HP [18,20,21,29,42,501 and LACA [l, 8,9,18,20,29,38,421 have been used repeatedly for such inhibition, frequently with chick embryo tissue [5,17,40,49,511. The capacity of NPXP to inhibit proteoglycan synthesis is also well known [6,26,36,371.…”