U Mukhtar1, A Goyal2, M Luthra-Guptasarma3, K Gauba1, A Kapur1, A K Thakur3. 1. Oral Health Sciences Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India. 2. Oral Health Sciences Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India. ashimapgi@yahoo.in. 3. Department of Immunopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Abstract
PURPOSE: Molar-incisor hypomineralization (MIH) is a qualitative developmental defect of enamel that affects first permanent molars with or without affecting permanent incisors. We aimed to carry out a quantitative proteomics-based study to compare and evaluate proteins in sound and MIH-affected enamel. MATERIALS AND METHODS: Ten blocks each of the MIH-affected enamel and sound enamel were processed and prepared for LC-MS/MS analysis. Label-free quantitation was carried out to evaluate the differentially expressed proteins in the two groups of samples. RESULTS: A significant increase in the number of proteins in MIH-affected enamel (50.3 ± 29.6) was observed compared to the sound enamel (21.4 ± 3.2). While proteins like collagens, α1-anti-trypsin, kallikrein-4 (KLK4), matrix metalloprotease-20 (MMP-20), alpha-2-macroglobulin, and alpha-2-HS-glycoprotein were upregulated in sound enamel, there was over-expression of albumin, calcium-binding proteins, anti-thrombin III, and dentin sialophosphoprotein (DSPP), along with proteins implicated in stress response and inflammatory processes in MIH. CONCLUSION: We propose that altered biomechanical properties of the enamel in MIH samples arise due to (i) down-regulation of proteins contributing to collagen biosynthesis and fibril formation; (ii) an overall imbalance in required levels of proteases (KLK4 and MMP-20) and anti-proteases (anti-thrombin-III which inhibits KLK-4), essential for optimal mineralization; (iii) very low levels of alpha-2-macroglobulin with important consequences in enamel mineralization and amelogenesis; and (iv) increased albumin in MIH, preventing proper growth of hydroxyapatite crystals. Increased inflammatory component was also seen in MIH; however, whether inflammation is a cause or consequence of the poor mineralization process needs to be assessed.
PURPOSE: Molar-incisor hypomineralization (MIH) is a qualitative developmental defect of enamel that affects first permanent molars with or without affecting permanent incisors. We aimed to carry out a quantitative proteomics-based study to compare and evaluate proteins in sound and MIH-affected enamel. MATERIALS AND METHODS: Ten blocks each of the MIH-affected enamel and sound enamel were processed and prepared for LC-MS/MS analysis. Label-free quantitation was carried out to evaluate the differentially expressed proteins in the two groups of samples. RESULTS: A significant increase in the number of proteins in MIH-affected enamel (50.3 ± 29.6) was observed compared to the sound enamel (21.4 ± 3.2). While proteins like collagens, α1-anti-trypsin, kallikrein-4 (KLK4), matrix metalloprotease-20 (MMP-20), alpha-2-macroglobulin, and alpha-2-HS-glycoprotein were upregulated in sound enamel, there was over-expression of albumin, calcium-binding proteins, anti-thrombin III, and dentin sialophosphoprotein (DSPP), along with proteins implicated in stress response and inflammatory processes in MIH. CONCLUSION: We propose that altered biomechanical properties of the enamel in MIH samples arise due to (i) down-regulation of proteins contributing to collagen biosynthesis and fibril formation; (ii) an overall imbalance in required levels of proteases (KLK4 and MMP-20) and anti-proteases (anti-thrombin-III which inhibits KLK-4), essential for optimal mineralization; (iii) very low levels of alpha-2-macroglobulin with important consequences in enamel mineralization and amelogenesis; and (iv) increased albumin in MIH, preventing proper growth of hydroxyapatite crystals. Increased inflammatory component was also seen in MIH; however, whether inflammation is a cause or consequence of the poor mineralization process needs to be assessed.
Authors: Yahya Açil; Ali E Mobasseri; Patrick H Warnke; Hendrik Terheyden; Jörg Wiltfang; Ingo Springer Journal: Calcif Tissue Int Date: 2004-11-04 Impact factor: 4.333