Lakkakorpi J, Li K, Decker S, Korkeela E, Piddington R, Abrams W, Bashir M, Uitto J, Rosenbloom J
Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19104, USA.
Connect Tissue Res. 1999;40(2):155-62. doi: 10.3109/03008209909029111.
We have previously shown in a transgenic mouse line, in which 5.2 kb of the elastin promoter was linked to the reporter enzyme chloramphenicol acetyltransferase (CAT), that the highest levels of expression were found in embryonic lungs and aorta, while lower levels were detected in other elastin-containing tissues. Furthermore, in general, expression of the transgene showed developmental regulation similar to that of the endogenous gene. However, the precise location of cellular expression could not be determined in this model. To overcome this limitation, we have developed a similar model, but replaced CAT with the reporter enzyme beta-galactosidase. Enzyme activity was readily detected in the transgenic mouse embryos in expected regions of tissue forming elastic fibers, including the dermis and elastic cartilage. Of considerable interest, however, was the novel finding of expression in specific areas of neuroepithelium of the brain and in the perichondrium surrounding areas destined to form hyaline cartilage in endochondral bone formation. These latter areas included all the bones of the limbs, the spine and rib cage. It appeared that these segments of elastin expression demarcated the border between the developing cartilage and the surrounding mesenchymal tissue. Elastin promoter expression was also found in developing somites, in the mesenchymal layer of the forming cornea of the eye, in the genital tubercle and in the epithelium destined to form the olfactory epithelium. These findings indicate that the elastin promoter is activated during embryonic development in a variety of tissues, suggesting that elastin gene expression may play a role in organizing cutaneous, skeletal and neural structures.
我们之前在一个转基因小鼠品系中进行了研究，该品系将5.2 kb的弹性蛋白启动子与报告酶氯霉素乙酰转移酶（CAT）相连，结果发现，胚胎肺和主动脉中的表达水平最高，而在其他含弹性蛋白的组织中表达水平较低。此外，一般来说，转基因的表达呈现出与内源基因相似的发育调控。然而，在这个模型中无法确定细胞表达的精确位置。为了克服这一局限性，我们开发了一个类似的模型，但将CAT替换为报告酶β-半乳糖苷酶。在转基因小鼠胚胎中，在形成弹性纤维的预期组织区域，包括真皮和弹性软骨中，很容易检测到酶活性。然而，相当有趣的是，在脑的神经上皮特定区域以及在软骨内骨形成过程中注定形成透明软骨区域周围的软骨膜中发现了新的表达。后一组区域包括四肢、脊柱和肋骨的所有骨骼。似乎这些弹性蛋白表达片段划定了发育中的软骨与周围间充质组织之间的边界。在发育中的体节、眼形成角膜的间充质层、生殖结节以及注定形成嗅觉上皮的上皮中也发现了弹性蛋白启动子的表达。这些发现表明，弹性蛋白启动子在胚胎发育过程中在多种组织中被激活，这表明弹性蛋白基因表达可能在组织皮肤、骨骼和神经结构中发挥作用。
