Durham P L, Snyder J M
Department of Anatomy, University of Iowa College of Medicine, Iowa City 52242, USA.
Dev Dyn. 1995 Aug;203(4):408-21. doi: 10.1002/aja.1002030404.
Laminin-1 is an extracellular matrix protein composed of three polypeptide chains that are designated alpha 1, beta 1, and gamma 1. We investigated the expression of laminin alpha 1, beta 1, and gamma 1 subunit chains during several stages of rabbit fetal lung development. Utilizing polyclonal antibodies directed against human placental laminin and immunoblot analysis, we found that the highest levels of laminin alpha 1, beta 1, and gamma 1 subunit chains in the fetal lung were present on day 26 of gestation (term = 31 days), coincident with the initiation of alveolar epithelial cell differentiation. Levels of the laminin chains were approximately five times higher in fetal lung at day 26 of gestation than in adult lung tissue. Different temporal patterns of laminin alpha 1, beta 1, and gamma 1 subunit chain expression were observed, data suggestive that the chains are independently regulated during lung development. Laminin was localized to the basement membranes of bronchi, bronchioles, prealveolar ducts, and blood vessels in fetal lung tissue, as shown by immunostaining with polyclonal laminin antibodies. A similar staining pattern was observed in adult lung tissue, but the alveolar wall was also stained. Laminin was also observed surrounding a few mesenchymal cells in fetal lung on day 19 of gestation; the number of positive mesenchymal cells increased with lung development. Laminin alpha 1 subunit chains, detected using a monoclonal antibody, were present in the basement membranes of bronchi, bronchioles, prealveolar ducts, and blood vessels in fetal lung tissue. No laminin alpha 1 chain staining was observed in the mesenchyme of early fetal lung tissue. Using a monoclonal antibody, laminin beta 1 subunit chains were immunolocalized in the basement membranes of bronchi, bronchioles, in prealveolar ducts, and surrounding some mesenchymal cells in fetal lung tissue. Laminin alpha 1 and beta 1 subunit chains in adult lung tissue were present in basement membranes of airways, blood vessels, and alveoli. Thus, changes in the localization and accumulation of laminin near the time of alveolar type I and type II epithelial cell differentiation suggest that laminin may play a role in mediating the differentiation of these cell types during rabbit fetal lung development.
层粘连蛋白-1是一种细胞外基质蛋白，由三条分别命名为α1、β1和γ1的多肽链组成。我们研究了兔胎儿肺发育几个阶段中层粘连蛋白α1、β1和γ1亚基链的表达情况。利用针对人胎盘层粘连蛋白的多克隆抗体和免疫印迹分析，我们发现胎儿肺中层粘连蛋白α1、β1和γ1亚基链的最高水平出现在妊娠第26天（足月为31天），这与肺泡上皮细胞分化的开始时间一致。妊娠第26天胎儿肺中层粘连蛋白链的水平比成年肺组织中大约高五倍。观察到层粘连蛋白α1、β1和γ1亚基链的不同时间表达模式，这些数据表明这些链在肺发育过程中是独立调节的。通过用多克隆层粘连蛋白抗体进行免疫染色显示，层粘连蛋白定位于胎儿肺组织中的支气管、细支气管、肺泡前导管和血管的基底膜。在成年肺组织中观察到类似的染色模式，但肺泡壁也被染色。在妊娠第19天的胎儿肺中还观察到层粘连蛋白围绕着一些间充质细胞；随着肺的发育，阳性间充质细胞的数量增加。使用单克隆抗体检测到的层粘连蛋白α1亚基链存在于胎儿肺组织中的支气管、细支气管、肺泡前导管和血管的基底膜中。在早期胎儿肺组织的间充质中未观察到层粘连蛋白α1链染色。使用单克隆抗体，层粘连蛋白β1亚基链被免疫定位在胎儿肺组织中的支气管、细支气管、肺泡前导管的基底膜以及围绕一些间充质细胞的部位。成年肺组织中的层粘连蛋白α1和β1亚基链存在于气道、血管和肺泡的基底膜中。因此，在I型和II型肺泡上皮细胞分化时附近层粘连蛋白的定位和积累变化表明，层粘连蛋白可能在兔胎儿肺发育过程中介导这些细胞类型的分化中发挥作用。
