Law A S, Burt D W, Alexander I, Thorp B H
Molecular Biology Division, Roslin Institute (Edinburgh), Midlothian.
Res Vet Sci. 1996 Sep;61(2):120-4. doi: 10.1016/s0034-5288(96)90085-5.
Previous immunolocalisation studies of dyschondroplasia have indicated that there is a reduction in the number of growth plate chondrocytes containing the protein transforming growth factor beta 3 (TGF-beta 3). The reduction in TGF-beta 3 in dyschondroplasia is likely to be a direct result of a reduction in the expression of the TGF-beta 3 gene. mRNA was extracted from small (0.09 g) samples of growth cartilage from the proximal tibiotarsus of three-week-old broiler chicks. The cartilage samples contained cells from all three zones of the growth plate (proliferative, transitional and upper hypertrophic) and were collected from normal and dyschondroplastic growth plates. The dyschondroplastic growth plates were identified by an accumulation of transitional chondrocytes which were considered to be a result of a failure to differentiate to the hypertrophic phenotype. A semi-quantitative polymerase chain reaction (PCR) was used to estimate the quantity of mRNA specific for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and for each of the three isoforms of TGF beta (TGF-beta 1, TGF-beta 2 and TGF-beta 3) in each of the cartilage samples. The levels of expression of mRNA for GAPDH, TGF-beta 1 and TGF-beta 2 were similar in the two groups, but the expression of TGF-beta 3 mRNA was significantly reduced in the samples from the dyschondroplastic growth plates. The reduction in TGF-beta 3 levels is thought to be associated with the failure of chondrocyte hypertrophy in dyschondroplasia, and provides in vivo evidence that TGF-beta 3 is part of the cascade of events associated with the differentiation of chondrocytes during endochondral ossification in the chick.
以往关于软骨发育异常的免疫定位研究表明，含有转化生长因子β3（TGF-β3）的生长板软骨细胞数量减少。软骨发育异常中TGF-β3的减少可能是TGF-β3基因表达降低的直接结果。从三周龄肉鸡胫骨近端生长软骨的小样本（0.09克）中提取mRNA。软骨样本包含生长板所有三个区域（增殖区、过渡区和上肥大区）的细胞，取自正常和发育异常的生长板。发育异常的生长板通过过渡软骨细胞的积累来识别，这些过渡软骨细胞被认为是未能分化为肥大表型的结果。采用半定量聚合酶链反应（PCR）来估计每个软骨样本中甘油醛-3-磷酸脱氢酶（GAPDH）以及TGF-β的三种同工型（TGF-β1、TGF-β2和TGF-β3）的特异性mRNA数量。两组中GAPDH、TGF-β1和TGF-β2的mRNA表达水平相似，但发育异常生长板样本中TGF-β3 mRNA的表达显著降低。TGF-β3水平的降低被认为与软骨发育异常中软骨细胞肥大失败有关，并提供了体内证据表明TGF-β3是雏鸡软骨内骨化过程中与软骨细胞分化相关的一系列事件的一部分。
