Stim1 Regulates Enamel Mineralization and Ameloblast Modulation

Area of Science:

• Cell Biology
• Developmental Biology
• Biochemistry

Background:

• Loss-of-function mutations in ORAI1 and STIM1 genes impair store-operated calcium entry (SOCE), causing ectodermal dysplasia and amelogenesis imperfecta.
• Limited patient tissue hinders direct analysis of enamel mineralization and ameloblast function in humans.

Purpose of the Study:

• To investigate the role of STIM1 and STIM2 in enamel formation and mineralization using conditional knockout mouse models.
• To analyze the impact of abrogating SOCE on ameloblast morphology and function during tooth development.

Main Methods:

• Generated ectodermal tissue-specific conditional knockout (cKO) mice for Stim1, Stim2, and both Stim1/2.
• Analyzed enamel phenotypes, including mineralization, structural integrity, and tooth morphology.
• Examined ameloblast morphology and gene expression of enamel matrix proteins and proteases.

Main Results:

• Ablation of Stim1 and Stim1/2, but not Stim2, resulted in chalky enamel with severe attrition and inferior mineralization.
• Enamel structural integrity was impaired in Stim1 and Stim1/2 cKO mice, though tooth shape and thickness remained normal.
• Ameloblast morphology was largely unaffected, but modulation cycles in maturation-stage ameloblasts were prolonged in Stim1 and Stim1/2 cKO incisors.

Conclusions:

• Store-operated calcium entry (SOCE) mediated by STIM proteins is essential for proper enamel mineralization.
• STIM1 plays a critical role in regulating ameloblast modulation during enamel maturation.
• These findings provide insights into the molecular mechanisms underlying amelogenesis imperfecta and tooth development.