Genetic disruption of CYP26B1 severely affects development of neural crest derived head structures, but does not
Glenn Maclean1, Pascal Dollé, Martin Petkovich
1Department of Pathology, Division of Cancer Biology and Genetics, Queen's University, Kingston, Ontario, Canada.
Abstract:
Cyp26b1 encodes a cytochrome-P450 enzyme that catabolizes retinoic acid (RA), a vitamin A derived signaling molecule. We have examined Cyp26b1(-/-) mice and report that mutants exhibit numerous abnormalities in cranial neural crest cell derived tissues. At embryonic day (E) 18.5 Cyp26b1(-/-) animals exhibit a truncated mandible, abnormal tooth buds, reduced ossification of calvaria, and are missing structures of the maxilla and nasal process. Some of these abnormalities may be due to defects in formation of Meckel's cartilage, which is truncated with an unfused distal region at E14.5 in mutant animals. Despite the severe malformations, we did not detect any abnormalities in rhombomere segmentation, or in patterning and migration of anterior hindbrain derived neural crest cells. Abnormal migration of neural crest cells toward the posterior branchial arches was observed, which may underlie defects in larynx and hyoid development. These data suggest different periods of sensitivity of anterior and posterior hindbrain neural crest derivatives to elevated levels of RA in the absence of CYP26B1.
Insights
Mice lacking the Cyp26b1 enzyme show severe craniofacial defects due to excess retinoic acid signaling. These defects impact neural crest development, affecting jaw, skull, and pharyngeal arch structures.
Area of Science:
- Developmental Biology
- Molecular Genetics
- Biochemistry
Background:
- Retinoic acid (RA) is a crucial signaling molecule derived from vitamin A, regulating embryonic development.
- Cytochrome P450 family 26 subfamily B member 1 (Cyp26b1) enzyme degrades RA, controlling its local concentration.
- Dysregulation of RA signaling is implicated in various developmental abnormalities.
Purpose of the Study:
- To investigate the role of Cyp26b1 in cranial neural crest development.
- To determine the consequences of Cyp26b1 deficiency on craniofacial structures.
- To elucidate the impact of elevated RA levels on neural crest cell derivatives.
Main Methods:
- Generation and analysis of Cyp26b1 knockout (Cyp26b1(-/-)) mice.
- Phenotypic characterization of craniofacial abnormalities at embryonic stages (E14.5, E18.5).
- Assessment of neural crest cell segmentation, patterning, and migration.
Main Results:
- Cyp26b1(-/-) mice exhibit truncated mandibles, abnormal tooth buds, reduced calvarial ossification, and missing maxillary/nasal structures.
- Meckel's cartilage formation is impaired in mutants.
- While anterior hindbrain neural crest development appears normal, posterior hindbrain neural crest cell migration is aberrant, affecting larynx and hyoid development.
Conclusions:
- Elevated RA levels due to Cyp26b1 deficiency cause significant craniofacial malformations.
- Different neural crest cell populations exhibit distinct sensitivities to RA during development.
- Cyp26b1 plays a critical role in regulating RA homeostasis for proper craniofacial and pharyngeal development.
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