Expression of tenomodulin in development mouse masseter muscle (731.2)

Abstract

Tenomodulin (TNMD) is related to the type II transmembrane glycoprotein, which contains an angiogenesis inhibitor with an antiangiogenic cysteine‐rich C‐terminal domain. TNMD functions as an anti‐angiogenic molecule and is expressed primarily in hypovascular tissues, such as tendons and ligaments. The masseter muscle contains a tendinous skeletal element that is an important site of masticatory dysfunction. However, the relationship between the RNA transcript levels of TNMD and angiogenic factors, such as vascular endothelial growth factor (VEGF), in the connective tissue of developing mouse masseter muscle is unknown. Method: Crlj:CD1 (ICR) mice were fed and sacrificed at the age of day E12.5, E14.5 E17.5, E18.5, 0 ,5, 10,15 and 20 by an overdose of pentobarbital. Fresh samples of right masseter muscle and femoris rectus were removed for further investigation (n=3 in each group). The study followed the regulations of Nippon Dental University (i.e., Rules for the Care and Use of LaboratoryAnimals, no. 03‐34). A quantitative real‐time reverse transcription polymerase chain reaction (RT‐PCR) was used to measure the RNA expression of mouse TNMD and other endothelial markers. We also determined the protein expression of the TNMD gene and other endothelial markers using an enzyme‐linked immunosorbent assay (ELISA). Result: In the masseter muscle of developing mice aged E12.5 to 5 days, the levels of TNMD mRNAs is appeared and high from E17.5 (ANOVA, p<0.001) but gradually decreased in 5‐day‐old mice (ANOVA, p<0.001). In contrast, VEGF and CD31 are different expression pattern and decreased in mice aged 0 to 20 days (ANOVA,p<0.001). The different expression of TNMD indicates formation of tendon in the masseter muscle at embryonic stages in contrast to that of other angiogenesis markers.