Proteolytic processing of dentin sialophosphoprotein (DSPP) is essential to dentinogenesis

Area of Science:

• Biomineralization
• Dentinogenesis
• Molecular Biology

Background:

• Dentin sialophosphoprotein (DSPP) is critical for dentin formation.
• DSPP undergoes proteolytic processing into functional fragments.
• The precise role of this processing in biomineralization requires elucidation.

Purpose of the Study:

• To investigate the necessity of DSPP proteolytic processing for its biological function in dentinogenesis.
• To determine if blocking DSPP cleavage affects dentin biomineralization.

Main Methods:

• Generation of transgenic mice (Dspp-KO/D452A-Tg) with a mutation blocking DSPP cleavage.
• Comparative analysis of dentin in Dspp-knock-out (Dspp-KO) mice, Dspp-KO/D452A-Tg mice, and Dspp-KO/normal-Tg mice.
• Assessment of dentin structure and DSPP processing using multipronged approaches.

Main Results:

• The D452A mutation effectively blocked in vivo proteolytic processing of DSPP in transgenic mice (90% uncleaved).
• Expression of normal DSPP fully rescued dentin defects in Dspp-KO mice.
• Expression of the non-cleavable D452A-DSPP mutant failed to rescue dentin defects.

Conclusions:

• Proteolytic processing of DSPP is an essential activation step for its biological function.
• This processing is indispensable for proper dentinogenesis and biomineralization.
• DSPP cleavage is a prerequisite for its role in forming healthy dentin.