Kouros-Mehr Hosein, Werb Zena
Department of Anatomy, Biomedical Sciences Program, University of California, San Francisco 94143-0452, USA.
Dev Dyn. 2006 Dec;235(12):3404-12. doi: 10.1002/dvdy.20978.
The mammary gland develops in a process known as branching morphogenesis, whereby a distal epithelial bud extends and bifurcates to form an extensive ductal network. Compared with other branched organs, such as the lung and kidney, little is known about the molecular basis of branching in the mammary gland. Here we report a microarray profiling strategy to identify novel genes that may regulate mammary branching. We microdissected terminal end bud (TEB) and mature duct microenvironments from beta-actin-green fluorescent protein reporter mice and compared their RNA expression profiles with epithelium-free mammary stroma by means of microarray. We identified 1,074 genes enriched in the TEB microenvironment, 222 genes enriched in the mature duct microenvironment, and 385 genes enriched in both TEB and mature duct microenvironments. The microarray correctly predicted the expression of genes known to be enriched in the epithelium (Ets-5) and stroma (MMP-14) of TEBs and in the mature duct microenvironment (MMP-3). The microarray also correctly predicted the localization of previously uncharacterized genes, such as the TEB-enriched SPRR-1a, the duct-enriched casein-gamma, and the general epithelial marker pleiotrophin. Analysis of genes enriched in TEBs revealed several genes in the Wnt (Wnt-2, Wnt-5a, Wnt-7b, Dsh-3, Frizzled-1, Frizzled-2), hedgehog (Dhh), ephrin (Ephrin-B1, Eph-A2), and transcription factor (Twist-1, Twist-2, Snail) families. In situ hybridization verified that these genes were enriched in the TEB epithelium (Wnt-5a, Wnt-7b, Dhh, Eph-A2) or TEB stroma (Wnt-2, Frizzled-1, Ephrin-B1). We discuss the potential roles of these genes in mammary branching morphogenesis.
乳腺在一个被称为分支形态发生的过程中发育，在此过程中，远端上皮芽延伸并分叉形成广泛的导管网络。与其他分支器官，如肺和肾相比，我们对乳腺分支的分子基础了解甚少。在此，我们报告一种微阵列分析策略，以鉴定可能调控乳腺分支的新基因。我们从β-肌动蛋白-绿色荧光蛋白报告基因小鼠中显微切割末端芽（TEB）和成熟导管微环境，并通过微阵列将它们的RNA表达谱与无上皮的乳腺基质进行比较。我们鉴定出1074个在TEB微环境中富集的基因、222个在成熟导管微环境中富集的基因以及385个在TEB和成熟导管微环境中均富集的基因。该微阵列正确预测了已知在TEB的上皮（Ets-5）和基质（MMP-14）以及成熟导管微环境（MMP-3）中富集的基因的表达。该微阵列还正确预测了先前未表征基因的定位，如在TEB中富集的SPRR-1a、在导管中富集的酪蛋白-γ以及一般上皮标志物多效生长因子。对在TEB中富集的基因的分析揭示了Wnt（Wnt-2、Wnt-5a、Wnt-7b、Dsh-3、卷曲蛋白-1、卷曲蛋白-2）、刺猬蛋白（Dhh）、ephrin（Ephrin-B1、Eph-A2）和转录因子（Twist-1、Twist-2、Snail）家族中的几个基因。原位杂交证实这些基因在TEB上皮（Wnt-5a、Wnt-7b、Dhh、Eph-A2）或TEB基质（Wnt-2、卷曲蛋白-1、Ephrin-B1）中富集。我们讨论了这些基因在乳腺分支形态发生中的潜在作用。
