Chen L H, Bissell M J
Lawrence Berkeley Laboratory, Division of Cell and Molecular Biology, University of California, Berkeley 94720.
Cell Regul. 1989 Nov;1(1):45-54. doi: 10.1091/mbc.1.1.45.
When primary mouse mammary epithelial cells (PMME) are cultured on a basement membrane type matrix, they undergo extensive morphogenesis leading to the formation of 3-dimensional alveoli-like spherical structures surrounding a closed lumen. We show for the first time that cells cultured on basement membrane-type matrix express high levels of whey acidic protein (WAP) mRNA and secrete the protein into the lumen. The expression of WAP appears to be dependent upon the formation of the alveoli-like spheres: prevention of sphere formation by fixation or drying of the matrix abolishes the expression of WAP. Co-culturing PMME on native and fixed basement membrane matrix indicates that the suppression of WAP expression is dominant, thereby revealing the existence of a diffusible inhibitor(s). The inhibitory activity is present in the conditioned medium of PMME cultured on plastic surface and floating collagen gels, substrata that do not form alveoli and do not allow WAP expression. These findings are consistent with the model that the synthesis, or the action, of the WAP inhibitory factor is regulated by the tissue-like multicellular organization of mammary cells. When PMME do not have correct 3-dimensional structures, one (or more) inhibitor is secreted into the medium which suppresses WAP expression by an autocrine or paracrine mechanism. Nuclear run-on experiments suggest that the suppression of WAP expression is posttranscriptional. These results have obvious bearings on the understanding of the mechanisms by which cell-cell and cell-extracellular matrix interaction regulate tissue specific gene expressions.
当原代小鼠乳腺上皮细胞（PMME）在基底膜型基质上培养时，它们会经历广泛的形态发生，形成围绕封闭管腔的三维肺泡样球形结构。我们首次表明，在基底膜型基质上培养的细胞表达高水平的乳清酸性蛋白（WAP）mRNA，并将该蛋白分泌到管腔中。WAP的表达似乎依赖于肺泡样球体的形成：通过固定或干燥基质来阻止球体形成会消除WAP的表达。在天然和固定的基底膜基质上共同培养PMME表明，WAP表达的抑制是显性的，从而揭示了一种可扩散抑制剂的存在。抑制活性存在于在塑料表面和漂浮胶原凝胶上培养的PMME的条件培养基中，这些基质不会形成肺泡且不允许WAP表达。这些发现与以下模型一致，即WAP抑制因子的合成或作用受乳腺细胞的组织样多细胞组织调节。当PMME没有正确的三维结构时，一种（或多种）抑制剂会分泌到培养基中，通过自分泌或旁分泌机制抑制WAP表达。核转录实验表明，WAP表达的抑制是转录后水平的。这些结果对于理解细胞-细胞和细胞-细胞外基质相互作用调节组织特异性基因表达的机制具有明显的意义。
