IADR Abstract Archives
Establishment of Mild Hypophosphatasia Mouse Models With ALPL Gene Variant
Objectives: Hypophosphatasia (HPP) is an inherited skeletal disease caused by an alkaline phosphatase (ALPL) gene variant. A compound heterozygous ALPL variant, c.1559delT and p.F327L, has been reported in perinatal benign HPP patient, while the p.R184W heterozygous variant is often found in odonto-type HPP cases. For this study, mouse models with knock-in ALPL variants were constructed and analyzed.
Methods: Three ALPL variant genetic sequences, c.1559delT, p.F327L, and p.R184W, were constructed and each was used to produce knock-in ICR mice. Heterozygous knock-in mice carrying a c.1559delT- or p.F327L-type variant were crossed with each other. Their three-week old offspring, as well as those of heterozygous knock-in mice with a p.R184W-type variant and wild-type mice underwent genotyping, were euthanized at 12 weeks. Serum alkaline phosphatase (ALP) level, and bone mineral dentistry (BMD) of mandibular and leg bones, based on micro-CT scanning results, were determined. To assess periodontal ligament strength, the mandibular first molar was extracted to determine maximum stress. Significant differences in examined factors between two groups were determined using Student’s t-test. Intergroup differences were estimated using analysis of variance, followed by Bonferroni correction. Statistical significance was considered at P<0.05.
Results: c.1559delT/p.F327L- and p.R184W heterozygous-type mice, average serum ALP and mandibular BMD values were significantly lower as compared to those in wild-type mice (P<0.001, P<0.05, respectively). However, there were no significant differences for leg bone BMD among these groups. Furthermore, maximum stress required for tooth extraction was significantly lower in c.1559delT/p.F327L and p.R184W heterozygous as compared to wild-type mice (P<0.05).
Conclusions: Mild HPP is often diagnosed based on dental symptoms, while affected individuals have few systemic bone symptoms. In the present study, mild HPP model mice with dental symptoms, but with negligible systemic symptoms were successfully constructed.
This study was supported by contributions from a READYFOR crowdfunding campaign (JM00000141).
Methods: Three ALPL variant genetic sequences, c.1559delT, p.F327L, and p.R184W, were constructed and each was used to produce knock-in ICR mice. Heterozygous knock-in mice carrying a c.1559delT- or p.F327L-type variant were crossed with each other. Their three-week old offspring, as well as those of heterozygous knock-in mice with a p.R184W-type variant and wild-type mice underwent genotyping, were euthanized at 12 weeks. Serum alkaline phosphatase (ALP) level, and bone mineral dentistry (BMD) of mandibular and leg bones, based on micro-CT scanning results, were determined. To assess periodontal ligament strength, the mandibular first molar was extracted to determine maximum stress. Significant differences in examined factors between two groups were determined using Student’s t-test. Intergroup differences were estimated using analysis of variance, followed by Bonferroni correction. Statistical significance was considered at P<0.05.
Results: c.1559delT/p.F327L- and p.R184W heterozygous-type mice, average serum ALP and mandibular BMD values were significantly lower as compared to those in wild-type mice (P<0.001, P<0.05, respectively). However, there were no significant differences for leg bone BMD among these groups. Furthermore, maximum stress required for tooth extraction was significantly lower in c.1559delT/p.F327L and p.R184W heterozygous as compared to wild-type mice (P<0.05).
Conclusions: Mild HPP is often diagnosed based on dental symptoms, while affected individuals have few systemic bone symptoms. In the present study, mild HPP model mice with dental symptoms, but with negligible systemic symptoms were successfully constructed.
This study was supported by contributions from a READYFOR crowdfunding campaign (JM00000141).