Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
PLoS One. 2010 Sep 17;5(9):e12817. doi: 10.1371/journal.pone.0012817.
Musladin-Lueke Syndrome (MLS) is a hereditary disorder affecting Beagle dogs that manifests with extensive fibrosis of the skin and joints. In this respect, it resembles human stiff skin syndrome and the Tight skin mouse, each of which is caused by gene defects affecting fibrillin-1, a major component of tissue microfibrils. The objective of this work was to determine the genetic basis of MLS and the molecular consequence of the identified mutation.
We mapped the locus for MLS by genome-wide association to a 3.05 Mb haplotype on canine chromosome 9 (CFA9 (50.11-54.26; p(raw) <10(-7))), which was homozygous and identical-by-descent among all affected dogs, consistent with recessive inheritance of a founder mutation. Sequence analysis of a candidate gene at this locus, ADAMTSL2, which is responsible for the human TGFβ dysregulation syndrome, Geleophysic Dysplasia (GD), uncovered a mutation in exon 7 (c.660C>T; p.R221C) perfectly associated with MLS (p-value=10(-12)). Murine ADAMTSL2 containing the p.R221C mutation formed anomalous disulfide-bonded dimers when transiently expressed in COS-1, HEK293F and CHO cells, and was present in the medium of these cells at lower levels than wild-type ADAMTSL2 expressed in parallel.
CONCLUSIONS/SIGNIFICANCE: The genetic basis of MLS is a founder mutation in ADAMTSL2, previously shown to interact with latent TGF-β binding protein, which binds fibrillin-1. The molecular effect of the founder mutation on ADAMTSL2 is formation of disulfide-bonded dimers. Although caused by a distinct mutation, and having a milder phenotype than human GD, MLS nevertheless offers a new animal model for study of GD, and for prospective insights on mechanisms and pathways of skin fibrosis and joint contractures.
Musladin-Lueke 综合征（MLS）是一种影响比格犬的遗传性疾病，表现为皮肤和关节广泛纤维化。在这方面，它类似于人类硬皮病综合征和 Tight skin 小鼠，它们都是由影响原纤维蛋白 1（组织微纤维的主要成分）的基因缺陷引起的。这项工作的目的是确定 MLS 的遗传基础和鉴定突变的分子后果。
我们通过全基因组关联将 MLS 的基因座定位到犬 9 号染色体（CFA9（50.11-54.26；p（raw）<10（-7）））上的一个 3.05 Mb 单倍型上，所有受影响的犬均为纯合且完全一致，符合隐性遗传的起始突变。在该基因座的候选基因 ADAMTSL2 上进行序列分析，该基因负责人类 TGFβ 失调综合征 Geleophysic 发育不良（GD），发现外显子 7 中的一个突变（c.660C>T；p.R221C）与 MLS 完全相关（p 值=10（-12））。瞬时表达在 COS-1、HEK293F 和 CHO 细胞中的含有 p.R221C 突变的鼠 ADAMTSL2 形成异常的二硫键结合二聚体，并且存在于这些细胞的培养基中，水平低于与平行表达的野生型 ADAMTSL2。
结论/意义：MLS 的遗传基础是 ADAMTSL2 的起始突变，先前已显示与潜伏 TGF-β 结合蛋白相互作用，该蛋白与原纤维蛋白 1 结合。起始突变对 ADAMTSL2 的分子影响是形成二硫键结合二聚体。尽管 MLS 由不同的突变引起，并且表型比人类 GD 更温和，但它仍然为研究 GD 提供了一个新的动物模型，并为皮肤纤维化和关节挛缩的机制和途径提供了潜在的见解。
