title: ENU-induced missense mutation in the C-propeptide coding region of Col2a1 creates a mouse model of platyspondylic lethal skeletal dysplasia, Torrance type.
abstract: The COL2A1 gene encodes the α1(II) chain of the homotrimeric type II collagen, the most abundant protein in cartilage. In humans, COL2A1 mutations create many clinical phenotypes collectively termed type II collagenopathies; however, the genetic basis of the phenotypic diversity is not well elucidated. Therefore, animal models corresponding to multiple type II collagenopathies are required. In this study we identified a novel Col2a1 missense mutation--c.44406A>C (p.D1469A)--produced by large-scale N-ethyl-N-nitrosourea (ENU) mutagenesis in a mouse line. This mutation was located in the C-propeptide coding region of Col2a1 and in the positions corresponding to a human COL2A1 mutation responsible for platyspondylic lethal skeletal dysplasia, Torrance type (PLSD-T). The phenotype was inherited as a semidominant trait. The heterozygotes were mildly but significantly smaller than wild-type mice. The homozygotes exhibited lethal skeletal dysplasias, including extremely short limbs, severe spondylar dysplasia, severe pelvic hypoplasia, and brachydactyly. As expected, these skeletal defects in the homozygotes were similar to those in PLSD-T patients. The secretion of the mutant proteins into the extracellular space was disrupted, accompanied by abnormally expanded rough endoplasmic reticulum (ER) and upregulation of ER stress-related genes, such as Grp94 and Chop, in chondrocytes. These findings suggested that the accumulation of mutant type II collagen in the ER and subsequent induction of ER stress are involved, at least in part in the PLSD-T-like phenotypes of the mutants. This mutant should serve as a good model for studying PLSD-T pathogenesis and the mechanisms that create the great diversity of type II collagenopathies.
authors.affiliation: Laboratory Animal Facility, Research Center for Medical Sciences, Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo 105-8461, Japan. furuichi@jikei.ac.jp
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Furuichi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masuya
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Murakami
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Nishida
authors.forename: Gen
authors.initials: G
authors.lastname: Nishimura
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kazunori
authors.initials: K
authors.lastname: Imaizumi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kudo
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ohkawa
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Wakana
authors.forename: Shiro
authors.initials: S
authors.lastname: Ikegawa
mesh_terms: D000423:Alcian Blue; D000818:Animals; D000880:Anthraquinones; D001842:Bone and Bones / Q000648:ultrastructure; D002874:Chromosome Mapping; D024043:Collagen Type II / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D004195:Disease Models, Animal; D005038:Ethylnitrosourea / Q000633:toxicity; D005838:Genotype; D007150:Immunohistochemistry; D051379:Mice; D008817:Mice, Mutant Strains / Q000235:genetics*; D046529:Microscopy, Electron, Transmission; D016296:Mutagenesis; D020125:Mutation, Missense / Q000187:drug effects / Q000235:genetics; D010009:Osteochondrodysplasias / Q000235:genetics* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000880:Anthraquinones; C447413:Col2a1 protein, mouse; D024043:Collagen Type II; D017931:DNA Primers; C010078:alizarin; D000423:Alcian Blue; D005038:Ethylnitrosourea