Ascorbic Acid Promotes Procollagen C-Proteinase Enhancer 1 Expression, Secretion, and Cell Membrane Localization

Removal of the C-propeptide from fibrillar procollagens is essential for collagen fibril assembly. The reaction is catalyzed by bone morphogenetic protein-1/tolloid-like proteinases and is accelerated by procollagen C-proteinase enhancer 1 (PCPE-1), an extracellular matrix glycoprotein that binds to the procollagen C-propeptide and its expression overlaps that of collagen. Ascorbic acid (Asc) is vital for collagen hydroxylation, folding, and secretion. It also increases collagen gene expression. The role of Asc as a regulator of PCPE-1 expression is debatable. To shed further light on this matter, herein, we studied the effects of Asc on PCPE-1 expression, secretion, and cellular localization in Rat2 and/or mouse 3T3 fibroblasts. Asc increased PCPE-1 expression at the translational and transcriptional levels about two-fold. It also increased the rate of PCPE-1 secretion approximately six-fold. Endogenous PCPE-1 was found to be cell associated, and Asc increased the amount of PCPE-1 on the cell surface. In the absence of PCPE-1 hydroxylation, we propose that the dependence of PCPE-1 secretion on Asc may be related to its role in procollagen secretion. Localization of PCPE-1 to the cell membrane favors the cell-surface as a physiological site of PCPE-1 action. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.