Hyperocclusion stimulates the expression of collagen type XII in periodontal ligament.

OBJECTIVES: It is known that excessive mechanical force exerted by hyperocclusion induces occlusal trauma. However, the mechanism of the process remains unclear. In the present study, we employed an in vivo hyperocclusion rodent model to examine morphological and biological mechanisms of occlusal trauma in periodontal ligament tissue. DESIGN: To investigate alveolar bone resorption, tooth sections were stained to detect osteoclasts. To investigate the relationship between hyperocclusion and the regeneration of the cell matrix, we examined the effect of hyperocclusal force on the expression of collagens using immunohistochemistry and quantitative PCR methods. RESULTS: The arrangement of collagen fibers in the furcation area of the teeth was undisturbed before hyperocclusion (control). Type I collagen was localized in the extracellular area at the furcation and there was faint expression and localization of type XII collagen in the periodontal ligament. The number of osteoclasts significantly increased in the furcation and lingual cervical regions on day 4 after hyperocclusion was induced. Type XII collagens were gradually up-regulated following the induction of hyperocclusion, in a time-dependent manner. Although type I collagen mRNA expression was stable before and after hyperocclusion, type XII collagen mRNA was significantly up-regulated on day 2 and day 4 after hyperocclusion treatment. CONCLUSIONS: Our findings indicate that hyperocclusal force predominantly up-regulates the expression of type XII collagen in periodontal tissue, but not type I collagen, suggesting that there is a mechanism for regeneration of periodontal tissues as a response to occlusal trauma.

Differential induction of collagens by mechanical stress in human periodontal ligament cells.

OBJECTIVE: Excessive mechanical stress (MS) during hyperocclusion is known to result in destruction of periodontal tissues and alveolar bone, leading to occlusal trauma. Collagens are extracellular matrix components that are encoded by more than 30 different genes. They are classified into three types: fibril-forming, fibril-associated with interrupted triple helices (FACIT), and non-fibril forming collagens. Although MS is known to affect COL I, little is known about its effects on other types of collagens in the periodontal ligament (PDL). We hypothesised that MS could induce expression of the three different types of collagens, thus protecting against occlusal trauma. DESIGN: The aim of this study was to investigate intermittent uniaxial stretching-induced collagen expression in PDL cells using DNA microarray, polymerase chain reaction, and western blotting analysis. We compared changes in collagen expression caused by MS stimulation and osteogenic stimulation, and examined relationships between expression of collagen and their digestive enzymes, matrix metalloproteases (MMPs). RESULTS: Expression of both fibril-forming and FACIT collagens was transiently decreased in the initial phase after MS, while the expression of non-fibril-forming collagens was gradually increased. MS for 3-7 days resulted in gradual upregulation of all three types of collagen. Furthermore, the expression of fibril- and non-fibril-forming collagens was reciprocally related to expression of MMPs. In contrast, expression of all three types of collagen was slightly upregulated during osteogenesis. CONCLUSION: The MS-induced expression patterns of fibril-forming and FACIT collagens suggest changes in the composition of the extracellular matrix to increase the resistance of PDL cells to hyperocclusal force.

Collagen XVI expression is upregulated in glioblastomas and promotes tumor cell adhesion.

The poor prognosis of glioblastoma patients is related to diffuse brain invasion and interaction of tumor cells with extracellular matrices (ECM). We describe expression and function of the FACIT-collagen XVI in glioblastomas. We found upregulation of collagen XVI mRNA as well as protein in glioblastomas as compared to normal cortex. SiRNA knockdown resulted in decreased cell adhesion whereas increased adhesion was observed on surfaces coated with collagen XVI. The migration of glioblastoma cells on this substrate remained unchanged. Our results demonstrate de-novo expression of collagen XVI in glioblastomas as part of the tumor specific remodeling of the ECM.

Genomic organization and characterization of the human type XXI collagen (COL21A1) gene.

We cloned a 4.1-kb full-length cDNA based on a reported human genomic clone containing a partial open reading frame (ORF) coding for a novel collagen-like protein. Sequence analysis indicated that the ORF codes for the alpha(1)-chain of type XXI collagen. Assembly of the genomic data reveals a complete sequence of the human gene COL21A1. COL21A1 is localized to chromosome 6p11.2-12.3, spanning 337 kb in size. The gene contains 31 exons, in which the 5'-untranslated exons 1 and 1a are alternatively spliced. The exon/domain organization of COL21A1 resembles that of the reported FACIT collagen genes, including COL9A1, COL9A2, COL9A3, and COL19A1, suggesting that these genes may have derived from the same ancestor FACIT gene by duplication. The expression of COL21A1 in human tissues is developmentally regulated, with a higher level at fetal stages. Type XXI collagen is an extracellular matrix component of the blood vessel walls, secreted by smooth-muscle cells. Platelet-derived growth factor (PDGF) has a pronounced effect on the stimulation of COL21A1 expression in cultured aortic smooth-muscle cells, suggesting that alpha1(XXI) collagen may contribute to the extracellular matrix assembly of the vascular network during blood vessel formation.