Proteomics-based identification of novel proteins in temporal tendons of patients with masticatory muscle tendon–aponeurosis hyperplasia

Masticatory muscle tendon–aponeurosis hyperplasia (MMTAH) is a new disease associated with limited mouth opening that is often misdiagnosed as a temporomandibular disorder; subsequently, patients are mistakenly treated with irreversible operations. Due to the poor presentation and characterization of symptoms, the underlying pathological conditions remain unclear. We have previously conducted a proteomic analysis of tendons derived from one MMTAH subject and one facial deformity subject using two-dimensional fluorescence difference gel electrophoresis and liquid chromatography coupled with tandem mass spectrometry. However, the results were obtained for only one subject. The aim of the present study was to confirm the expression of specific molecules in tendon tissues from multiple subjects with MMTAH by applying two-dimensional polyacrylamide gel electrophoresis with matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Of the 19 proteins identified in tendons from both MMTAH and facial deformity patients, fibrinogen fragment D and beta-crystallin A4 were up-regulated, whereas myosin light chain 4 was down-regulated in MMTAH. We also found fibrinogen to be expressed robustly in tendon tissues of MMTAH patients. Our data provide the possibility that the distinctive expression of these novel proteins is associated with the pathology of MMTAH.