A study on an aberrant differentiation into chondrocytes in progressive ankylosis (ank/ank)

进行性关节强直是一种常染色体隐性遗传的小鼠骨骼疾病。为了研究ank/ank小鼠关节的确切病理变化，从ank/+和ank/ank小鼠中取出关节组织，石蜡包埋，并用H. E.染色切片。在4周龄的ank/ank小鼠中，观察到滑膜细胞分化为软骨细胞，并且滑膜因软骨细胞的增殖而增厚。在一只8周龄的小鼠中，增厚的滑膜部分钙化，关节软骨的表面变得不规则。为了定位进行性关节强直的致病基因，我们分析了15号染色体遗传标记处的重组事件，使用F2纯合子小鼠与其他品系小鼠流血的。在400个减数分裂中，我们发现了6个重组在D15 Mit 130的重组最小。我们将Ank基因定位在D15 Mit 130和D15 Mit 6之间的1.25 cM区域。为了缩小该区域，我们计划用BAC克隆和oligo GT引物寻找多态性标记，因为该区域没有更多的信息标记。我们利用抑制性消减杂交（SSH）进行克隆。结果，我们目前获得了两个阳性克隆，它们在ank/ank小鼠的组织中的表达低于未受影响的小鼠。为进一步研究，我们将cDNA扩增至全长并定位基因位点。

Progressive ankylosis (ank/ank) is an autosomal recessive skeletal disorder in mice. To investigate the precise pathological changes in the joints of ank/ank, the joint tissues were removed from ank/+ and ank/ank mice, paraffin-embedded, and examined with H.E. stained sections. In a 4 week-old ank/ank mouse, the differentiation of synovial cells into chondrocytes was seen and the synovial membrane was thickened by the proliferation of the chondrocytes. In an 8 week-old mouse, the thickened synovial membranes were partially calcified and the surface of the articular cartilage became irregular.To map the causative gene of progressive ankylosis, we analyzed the recombination events at genetic markers in chromosome 15 using F2 homozygous mice bled with the other strain mice. Of 400 meioses, we found 6 recombinations at D15Mit130 for the minimum of recombination. We assigned the Ank locus to the 1.25 cM region between D15Mit130 and D15Mit6. To narrow down the region, we plan to find polymorphic markers with BAC clones and oligo GT primers because there is no more informative marker in the region.In parallel with the positional cloning, the subtraction cloning was carried out. We took advantage of suppression subtractive hybridization (SSH) for the cloning. As a result, we obtained, at the present time, two positive clones that are expressed less in the tissues of ank/ank mice than those of unaffected mice. For the further study we sill extend the cDNAs to the full length and map the gene loci.