Transcriptional regulation and proteolytic processing of perlecan in mast cells lead to the production of forms that contain the alpha2/beta1 integrin binding site: roles in wound healing and tissue regeneration (544.3)

Abstract

This study demonstrated that primary human mast cells as well as the rat and human mast cell lines, RBL‐2H3 and HMC‐1, produce the heparan sulfate proteoglycan (HSPG), perlecan, with a Mr of 640kDa as well as smaller molecular weight species of 300 and 130kDa. Utilizing domain‐specific antibodies and N‐terminal sequencing we confirmed that both forms contained the C‐terminal module of the protein core, which were generated by mast cell‐derived proteases. Fractions from mast cell cultures that were enriched for these fragments were shown to bind endothelial cells via the alpha2/beta1 integrin and stimulate the migration of cells in “scratch assays”. Both of these activities were inhibited by incubation with antibodies reactive to the C‐terminus of the perlecan protein core. This study showed that the transcriptional regulation of the HSPG2 gene is more complex than first thought, particularly in mast cells. Domain specific RT‐PCR experiments demonstrated that these cells were capable of splicing the perlecan gene (HSPG2) and when we performed quantitative PCR experiments, we demonstrated that the C‐terminal region was over‐represented compared to the N‐terminal region. This together with the data demonstrating proteolytic processing suggest that the C‐terminal region of perlecan, which contains the alpha2/beta1 integrin binding site may have downstream biological functions that regulate angiogenesis and matrix turnover and thereby promote wound healing and tissue regenerative processes.