Novel identification of matrix proteins involved in calcitic biomineralization.

Abstract

Biomineralization is essential for the development of hard tissues in vertebrates, which includes both calcium phosphate and calcium carbonate structures. Calcitic mineralization by calcium carbonate is an important process in the formation of otoconia, which are gravity receptor organs located in the inner ear and are responsible for balance and for sensing linear acceleration. Deficiencies in the regulation of their biomineralization can lead to otoconia degeneration and eventually benign paroxysmal position vertigo (BPPV), which is the main cause of vertigo in humans. Eggshell formation in chicken is one of the fastest known biomineralization processes and is an excellent model for the study of calcitic biomineralization. Cross-analysis of proteomic data from two mineralized models, fertilized and unfertilized chicken eggshells, identified proteins associated with the mammillary cones that are the sites of initiation of eggshell formation. We hypothesize that these proteins regulate the earliest stages of eggshell calcification. The human homologs of these proteins are therefore potential candidates to play a role in otoconia biomineralization.