Deciphering the functions of Stromal Interaction Molecule-1 in amelogenesis using AmelX-iCre mice

Area of Science:

• Biomineralization
• Cell Biology
• Genetics

Background:

• Stromal interaction molecule 1 (STIM1) is an intracellular Ca2+ sensor crucial for cellular functions.
• Mutations in STIM1 are linked to Amelogenesis Imperfecta (AI), a developmental disorder affecting tooth enamel.
• STIM1's specific role in ameloblast differentiation and enamel matrix formation requires detailed investigation.

Purpose of the Study:

• To characterize the enamel phenotype in ameloblast-specific Stim1 conditional knockout (cKO) mice.
• To investigate the impact of STIM1 loss on ameloblast gene expression and enamel mineralization.
• To elucidate the role of STIM1 in regulating calcium transport and mitochondrial function in ameloblasts.

Main Methods:

• Generation of ameloblast-specific Stim1 cKO mice by crossing AmelX-iCre with Stim1-floxed strains.
• Enamel phenotyping using scanning electron microscopy, energy dispersive spectroscopy, and micro-CT.
• Gene expression analysis via RNAseq and RT-qPCR; protein detection through immunohistochemistry.

Main Results:

• Stim1 cKO mice displayed a hypomineralized AI phenotype with reduced enamel volume, mineral density, and calcium content.
• The enamel defects were more severe in older mice and more pronounced in incisors than molars.
• STIM1 ablation altered gene expression related to enamel matrix proteins, calcium transport, and mitochondrial kinetics in incisors.

Conclusions:

• Loss of STIM1 in ameloblasts leads to hypomineralized enamel, consistent with Amelogenesis Imperfecta.
• STIM1 plays a significant role in regulating enamel mineralization and ameloblast function.
• STIM1 deficiency affects gene expression patterns critical for enamel development, particularly impacting incisor enamel.