Ohkura, N.; Nam, H.K.; Liu, F.; Hatch, N. Cranial Neural Crest Specific Deletion of Alpl (TNAP) via P0-Cre Causes Abnormal Chondrocyte Maturation and Deficient Cranial Base Growth. Int. J. Mol. Sci.2023, 24, 15401.
Ohkura, N.; Nam, H.K.; Liu, F.; Hatch, N. Cranial Neural Crest Specific Deletion of Alpl (TNAP) via P0-Cre Causes Abnormal Chondrocyte Maturation and Deficient Cranial Base Growth. Int. J. Mol. Sci. 2023, 24, 15401.
Ohkura, N.; Nam, H.K.; Liu, F.; Hatch, N. Cranial Neural Crest Specific Deletion of Alpl (TNAP) via P0-Cre Causes Abnormal Chondrocyte Maturation and Deficient Cranial Base Growth. Int. J. Mol. Sci.2023, 24, 15401.
Ohkura, N.; Nam, H.K.; Liu, F.; Hatch, N. Cranial Neural Crest Specific Deletion of Alpl (TNAP) via P0-Cre Causes Abnormal Chondrocyte Maturation and Deficient Cranial Base Growth. Int. J. Mol. Sci. 2023, 24, 15401.
Abstract
Bone growth plate abnormalities and skull shape defects are seen in hypophosphatasia, a heritable disorder in humans that occurs due to deficiency of Tissue Nonspecific Alkaline Phosphatase (TNAP, Alpl) enzyme activity. Abnormal development of the cranial base growth plates (synchondroses) and abnormal skull shapes have also been demonstrated in global TNAP-/- mice. To distinguish local vs. systemic effects of TNAP on skull development, we utilized P0-Cre to knockout TNAP only in cranial neural crest derived tissues using TNAP flox mice. Here we show that TNAP deficiency in cranial neural crest leads to leads to skull shape defects and deficient growth of the intersphenoid synchondrosis (ISS). ISS chondrocyte abnormalities included increased proliferation in resting and proliferative zones with decreased apoptosis in hypertrophic zones. ColX expression is increased, indicative of premature differentiation in the absence of TNAP. Sox9 expression is increased in both resting and prehypertrophic zones of mutant mice. Expression of PTHrP and IHH were also increased. Finally, cranial base organ culture revealed that inorganic phosphate (Pi) and pyrophosphate (PPi) have specific effects on cell signaling and phenotype changes in the ISS. Together, these results demonstrate that TNAP expression in growth plate chondrocytes is essential for normal development, and that the mechanism likely involves Sox9, PTHrP, IHH and PPi.
Biology and Life Sciences, Cell and Developmental Biology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
