PUBLICATION

Abnormal chondrocyte development in a zebrafish model of cblC syndrome restored by an MMACHC cobalamin binding mutant

Authors
Paz, D., Pinales, B.E., Castellanos, B.S., Perez, I., Gil, C.B., Madrigal, L.J., Reyes-Nava, N.G., Castro, V.L., Sloan, J.L., Quintana, A.M.
ID
ZDB-PUB-230512-41
Date
2023
Source
Differentiation; research in biological diversity   131: 748174-81 (Journal)
Registered Authors
Quintana, Anita
Keywords
Craniofacial development, MMACHC, cblC, cblX
MeSH Terms
  • Amino Acid Metabolism, Inborn Errors*/genetics
  • Animals
  • Carrier Proteins/genetics
  • Carrier Proteins/metabolism
  • Chondrocytes/metabolism
  • Mice
  • Mutation
  • Vitamin B 12/genetics
  • Vitamin B 12/metabolism
  • Zebrafish*/genetics
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
PubMed
37167860 Full text @ Differentiation
Abstract
Variants in the MMACHC gene cause combined methylmalonic acidemia and homocystinuria cblC type, the most common inborn error of intracellular cobalamin (vitamin B12) metabolism. cblC is associated with neurodevelopmental, hematological, ocular, and biochemical abnormalities. In a subset of patients, mild craniofacial dysmorphia has also been described. Mouse models of Mmachc deletion are embryonic lethal but cause severe craniofacial phenotypes such as facial clefts. MMACHC encodes an enzyme required for cobalamin processing and variants in this gene result in the accumulation of two metabolites: methylmalonic acid (MMA) and homocysteine (HC). Interestingly, other inborn errors of cobalamin metabolism, such as cblX syndrome, are associated with mild facial phenotypes. However, the presence and severity of MMA and HC accumulation in cblX syndrome is not consistent with the presence or absence of facial phenotypes. Thus, the mechanisms by which mutations in MMACHC cause craniofacial defects are yet to be completely elucidated. Here we have characterized the craniofacial phenotypes in a zebrafish model of cblC (hg13) and performed restoration experiments with either a wildtype or a cobalamin binding deficient MMACHC protein. Homozygous mutants did not display gross morphological defects in facial development but did have abnormal chondrocyte nuclear organization and an increase in the average number of neighboring cell contacts, both phenotypes were fully penetrant. Abnormal chondrocyte nuclear organization was not associated with defects in the localization of neural crest specific markers, sox10 (RFP transgene) or barx1. Both nuclear angles and the number of neighboring cell contacts were fully restored by wildtype MMACHC and a cobalamin binding deficient variant of the MMACHC protein. Collectively, these data suggest that mutation of MMACHC causes mild to moderate craniofacial phenotypes that are independent of cobalamin binding.
Genes / Markers
Figures
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping