cDNA Cloning of S100 Calcium-binding Proteins from Bovine Periodontal Ligament and Their Expression in Oral Tissues

Abstract

The periodontal ligament (PDL) is a unique tissue that is crucial for tooth function. However, little is known of the molecular mechanisms controlling PDL function. To characterize PDL cells at the molecular level, we constructed a cDNA library from bovine PDL tissue. We then focused on the isolation of S100 calcium-binding proteins (CaBPs), because they mediate Ca2+ signaling and control important cellular processes such as differentiation and metabolism. We screened the PDL cDNA library with a mouse S100A4 cDNA, and cloned the bovine cDNAs of two S100 CaBPs (S100A4 and S100A2). In northern blotting analysis, the highest expression of S100A4 was detected in PDL from erupted teeth (PDLE). PDL from teeth under eruption (PDLU) showed a lower expression of S100A4, and its expression in gingiva was faintly detectable. S100A4 expression was also high in the pulp tissue followed by the dental papilla of the tooth germ. S100A2 expression was high in PDLE and gingiva. Interestingly, only PDLE exhibited a high expression of both S100A4 and S100A2. PDLE also expressed the highest level of beta-actin, a target cytoskeletal protein for S100A4. It is conceivable that the high expression of S100A4 in PDLE is a result of the maturation of the PDL and/or a response to mechanical stress generated by mastication. Since there was a marked difference of S100A4 expression between PDL and gingiva, we propose that S100A4 could be a useful marker for distinguishing cells from these two tissues.

Isolation and Characterization of Cultured Human Periodontal Ligament Fibroblast-Specific cDNAs

“…It has been reported that, although S100A4 was only weakly expressed in dental papilla, dental follicle, and pulp tissue and not in gingival tissue, it was selectively and strongly expressed in PDL. In contrast, although S100A2 was not expressed in dental papilla, dental follicle, and pulp tissue, it was strongly expressed in both gingival tissue and PDL (17). Therefore, S1004A is more useful than S1002A for comparing the characteristics of gingiva and PDL, which is in agreement with previous report.…”

“…Two S100 calcium-binding proteins, S100A4 and S100A2, were isolated from bovine periodontal tissues, and it was suggested that S100A4 might be a useful marker for distinguishing cells from the PDL and gingiva (17). It was also proposed that S100A4 had an extracellular role as a mineralization inhibitor, which is responsible for maintaining the periodontal ligament space (18).…”

Identification of Matrix Mineralization-Related Genes in Human Periodontal Ligament Cells Using cDNA Microarray

“…Interestingly Strutz et al 25) have isolated one S100 calcium-binding protein known as S100A4 as a fibroblast-specific protein and demonstrated its high gene expression in the periodontal mesenchyme during early stages of tooth morphogenesis in an in situ hybridization study. S100A4 might be a useful marker for distinguishing cells of the PDL from the gingiva 26) . S100A4 has an extracellular role as a mineralization inhibitor, which is responsible for maintaining the periodontal ligament space 27) .…”

Interferon-γ suppresses S100A4 transcription independently of apoptosis or cell cycle arrest

“…Several studies have indicated that S100 proteins, due to their Ca 2 þ -binding properties, are involved in regulating intracellular Ca 2 þ homeostasis or Ca 2 þ -dependent cell signalling (Boni et al, 1997;Duarte et al, 1998). In addition, an intracellular relocation of S100A4 upon treatment with thapsigargin has been reported (Mueller et al, 1999).…”