Institute of Medical Biology, A(∗)STAR, Singapore.
Am J Hum Genet. 2010 Dec 10;87(6):768-78. doi: 10.1016/j.ajhg.2010.11.005.
We delineated a syndromic recessive preaxial brachydactyly with partial duplication of proximal phalanges to 16.8 Mb over 4 chromosomes. High-throughput sequencing of all 177 candidate genes detected a truncating frameshift mutation in the gene CHSY1 encoding a chondroitin synthase with a Fringe domain. CHSY1 was secreted from patients' fibroblasts and was required for synthesis of chondroitin sulfate moieties. Noticeably, its absence triggered massive production of JAG1 and subsequent NOTCH activation, which could only be reversed with a wild-type but not a Fringe catalytically dead CHSY1 construct. In vitro, depletion of CHSY1 by RNAi knockdown resulted in enhanced osteogenesis in fetal osteoblasts and remarkable upregulation of JAG2 in glioblastoma cells. In vivo, chsy1 knockdown in zebrafish embryos partially phenocopied the human disorder; it increased NOTCH output and impaired skeletal, pectoral-fin, and retinal development. We conclude that CHSY1 is a secreted FRINGE enzyme required for adjustment of NOTCH signaling throughout human and fish embryogenesis and particularly during limb patterning.
我们描绘了一种综合征性常染色体隐性近侧短指畸形伴近端指骨部分重复，涉及 4 条染色体，跨度为 16.8Mb。对所有 177 个候选基因进行高通量测序，发现编码具有 Fringe 结构域的软骨素合酶的 CHSY1 基因存在截断的移码突变。CHSY1 从患者的成纤维细胞中分泌出来，是合成软骨素硫酸盐部分所必需的。值得注意的是，其缺失会触发 JAG1 的大量产生和随后的 NOTCH 激活，而只有野生型 CHSY1 构建体而非 Fringe 催化失活的 CHSY1 构建体能逆转这种情况。在体外，通过 RNAi 敲低 CHSY1 会导致胎成骨细胞中骨生成增强，胶质母细胞瘤细胞中 JAG2 的显著上调。在体内，斑马鱼胚胎中的 chsy1 敲低部分模拟了人类疾病；它增加了 NOTCH 输出，并损害了骨骼、胸鳍和视网膜的发育。我们得出结论，CHSY1 是一种分泌型 FRINGE 酶，在人类和鱼类胚胎发生过程中，特别是在肢体模式形成过程中，对 NOTCH 信号的调节是必需的。
