Lethal skeletal dysplasia in mice and humans lacking the golgin GMAP-210.
BACKGROUND
Establishing the genetic basis of phenotypes such as skeletal dysplasia in model organisms can provide insights into biologic processes and their role in human disease.


METHODS
We screened mutagenized mice and observed a neonatal lethal skeletal dysplasia with an autosomal recessive pattern of inheritance. Through genetic mapping and positional cloning, we identified the causative mutation.


RESULTS
Affected mice had a nonsense mutation in the thyroid hormone receptor interactor 11 gene (Trip11), which encodes the Golgi microtubule-associated protein 210 (GMAP-210); the affected mice lacked this protein. Golgi architecture was disturbed in multiple tissues, including cartilage. Skeletal development was severely impaired, with chondrocytes showing swelling and stress in the endoplasmic reticulum, abnormal cellular differentiation, and increased cell death. Golgi-mediated glycosylation events were altered in fibroblasts and chondrocytes lacking GMAP-210, and these chondrocytes had intracellular accumulation of perlecan, an extracellular matrix protein, but not of type II collagen or aggrecan, two other extracellular matrix proteins. The similarities between the skeletal and cellular phenotypes in these mice and those in patients with achondrogenesis type 1A, a neonatal lethal form of skeletal dysplasia in humans, suggested that achondrogenesis type 1A may be caused by GMAP-210 deficiency. Sequence analysis revealed loss-of-function mutations in the 10 unrelated patients with achondrogenesis type 1A whom we studied.


CONCLUSIONS
GMAP-210 is required for the efficient glycosylation and cellular transport of multiple proteins. The identification of a mutation affecting GMAP-210 in mice, and then in humans, as the cause of a lethal skeletal dysplasia underscores the value of screening for abnormal phenotypes in model organisms and identifying the causative mutations.
Smits
Patrick
P
Orthopedic Research Laboratories, Department of Orthopedic Surgery, Children's Hospital, Boston, MA 02115, USA.
Bolton
Andrew D
AD
Funari
Vincent
V
Hong
Minh
M
Boyden
Eric D
ED
Lu
Lei
L
Manning
Danielle K
DK
Dwyer
Noelle D
ND
Moran
Jennifer L
JL
Prysak
Mary
M
Merriman
Barry
B
Nelson
Stanley F
SF
Bonafé
Luisa
L
Superti-Furga
Andrea
A
Ikegawa
Shiro
S
Krakow
Deborah
D
Cohn
Daniel H
DH
Kirchhausen
Tom
T
Warman
Matthew L
ML
Beier
David R
DR
D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D019902:Chondrocytes / Q000166:cytology*; D018389:Codon, Nonsense; D003598:Cytoskeletal Proteins; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005808:Genes, Recessive; D006031:Glycosylation; D006056:Golgi Apparatus / Q000648:ultrastructure; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics*; D010009:Osteochondrodysplasias / Q000235:genetics*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011499:Protein Processing, Post-Translational / Q000502:physiology; D017422:Sequence Analysis, DNA
D018389:Codon, Nonsense; D003598:Cytoskeletal Proteins; D009687:Nuclear Proteins; C109331:TRIP11 protein, human; C534613:TRIP11 protein, mouse