Institute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
Cells Tissues Organs. 2010;192(1):17-27. doi: 10.1159/000280416. Epub 2010 Feb 4.
Notch signalling, via its downstream mediators HES1 and HES5, regulates development of several different tissues. In vitro studies suggest that these genes are also involved in chondrogenesis and endochondral bone formation. In order to investigate the importance of HES1 and HES5 for these developmental processes, mice lacking chondrogenic expression of HES1 and HES5 were constructed by interbreeding HES5(-/-) mice homozygous for the floxed HES1 allele (HES1(flox/flox)) with COL2A1-Cre transgenic mice, creating conditional HES1;HES5 double mutant mice. The formation of cartilage and endochondral bone was studied in these mice using histological and immunohistochemical stainings, including Alcian Blue van Gieson, Safranin-O, modified Mallory Aniline Blue, tartrate-resistant acid phosphatase and collagen type II stainings. The mice were also studied using several different morphometrical analyses and the differentiation potential of the chondrocytes was evaluated in vitro. Unexpectedly, the conditional HES1;HES5 double mutant mice did not display impaired development of cartilage or endochondral bone. Lack of altered phenotype in the conditional HES1;HES5 double mutant mice can be explained either by the HES1 and HES5 genes not being involved in cartilage and endochondral bone development or by functional redundancy between the genes belonging to the family of HES genes: that is, disruption of one gene could be compensated for by the activity of another. Our results further shed light on the compensatory reserves available during the developing cartilage and bone.
Notch 信号通路通过其下游介质 HES1 和 HES5 调控多种组织的发育。体外研究表明，这些基因也参与软骨生成和软骨内骨形成。为了研究 HES1 和 HES5 对这些发育过程的重要性，通过将 HES5(-/-) 小鼠（HES1 等位基因纯合的 floxed）与 COL2A1-Cre 转基因小鼠杂交，构建了缺乏软骨形成表达的 HES1 和 HES5 的 HES1(flox/flox) 条件性 HES1;HES5 双突变小鼠。使用组织学和免疫组织化学染色（包括阿尔辛蓝 van Gieson、番红 O、改良的 Mallory 苯胺蓝、抗酒石酸酸性磷酸酶和胶原 II 染色）研究这些小鼠中软骨和软骨内骨的形成。还使用几种不同的形态计量学分析研究了这些小鼠，并在体外评估了软骨细胞的分化潜力。出乎意料的是，条件性 HES1;HES5 双突变小鼠并未显示出软骨或软骨内骨发育受损。条件性 HES1;HES5 双突变小鼠的表型未改变，可以解释为 HES1 和 HES5 基因未参与软骨和软骨内骨发育，或者 HES 基因家族中的基因之间存在功能冗余：即，一个基因的缺失可以由另一个基因的活性来补偿。我们的结果进一步阐明了发育中的软骨和骨骼中可用的补偿储备。
