A Zebrafish Model Of PMM2-CDG Reveals Altered Neurogenesis And A Substrate-Accumulation Mechanism For N-Linked Glycosylation Deficiency
- Authors
- Cline, A., Gao, N., Flanagan-Steet, H., Sharma, V., Rosa, S., Sonon, R., Azadi, P., Sadler, K.C., Freeze, H.H., Lehrman, M.A., and Steet, R.
- ID
- ZDB-PUB-120909-7
- Date
- 2012
- Source
- Molecular biology of the cell 23(21): 4175-4187 (Journal)
- Registered Authors
- Flanagan-Steet, Heather, Rosa, Sabrina, Sadler Edepli, Kirsten C., Steet, Richard
- Keywords
- none
- MeSH Terms
-
- Animals
- Cartilage/drug effects
- Cartilage/embryology
- Cartilage/pathology
- Cell Shape/drug effects
- Chondrocytes/drug effects
- Chondrocytes/metabolism
- Chondrocytes/pathology
- Congenital Disorders of Glycosylation/enzymology*
- Congenital Disorders of Glycosylation/genetics
- Congenital Disorders of Glycosylation/pathology*
- Craniofacial Abnormalities/embryology
- Craniofacial Abnormalities/pathology
- Disease Models, Animal
- Embryo, Nonmammalian/abnormalities
- Embryo, Nonmammalian/drug effects
- Embryo, Nonmammalian/enzymology
- Gene Expression Regulation, Developmental/drug effects
- Glycosylation/drug effects
- Lipopolysaccharides/metabolism
- Mannose-6-Phosphate Isomerase/metabolism
- Mannosephosphates/metabolism
- Morpholinos/pharmacology
- Motor Neurons/drug effects
- Motor Neurons/pathology
- Movement/drug effects
- Neurogenesis*/drug effects
- Phosphotransferases (Phosphomutases)/deficiency
- Phosphotransferases (Phosphomutases)/genetics
- Phosphotransferases (Phosphomutases)/metabolism*
- Skull/abnormalities
- Skull/drug effects
- Skull/embryology
- Spinal Cord/drug effects
- Spinal Cord/embryology
- Spinal Cord/pathology
- Substrate Specificity/drug effects
- Zebrafish/embryology
- Zebrafish/genetics
- Zebrafish/metabolism*
- Zebrafish Proteins/deficiency
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism*
- PubMed
- 22956764 Full text @ Mol. Biol. Cell
Congenital Disorder of Glycosylation PMM2-CDG results from mutations in PMM2, which encodes the phosphomannomutase that converts mannose-6-P to mannose-1-P. Patients have wide-spectrum clinical abnormalities associated with impaired protein N-glycosylation. Though widely proposed that PMM2 deficiency depletes mannose-1-P, a precursor of GDP-mannose, and consequently suppresses lipid-linked oligosaccharide (LLO) levels needed for N-glycosylation, these deficiencies have not been demonstrated in patients or any animal model. Here, we report a morpholino-based PMM2-CDG model in zebrafish. Morphant embryos had developmental abnormalities consistent with PMM2-CDG patients, including craniofacial defects and impaired motility associated with altered motor neurogenesis within the spinal cord. Significantly, global N-linked glycosylation and LLO levels were reduced in pmm2 morphants. While mannose-1-P and GDP-mannose were below reliable detection/quantification limits, Pmm2 depletion unexpectedly caused accumulation of mannose-6-P, shown earlier to promote LLO cleavage in vitro. In pmm2 morphants, the free glycan by-products of LLO cleavage increased nearly twofold. Suppression of the mannose-6-P synthesizing enzyme, mannose phosphate isomerase, within the pmm2 background normalized mannose-6-P levels and certain aspects of the craniofacial phenotype, and abrogated pmm2-dependent LLO cleavage. In summary, we report the first zebrafish model of PMM2-CDG and uncover novel cellular insights not possible with other systems, including a mannose-6-P accumulation mechanism for under-glycosylation.