細胞外基質影響泌乳激素訊息傳遞之機制

The mechanism involved in extracellular matrix-mediated regulation of prolactin signaling

杜軍毅(Jyun-Yi Du)

指導教授 ： 李宜儒

中山醫學大學/醫學院/醫學研究所/碩士(2007年)

摘要

對乳腺上皮細胞而言，泌乳激素的訊息傳遞是需要細胞黏附在基底膜上。然而，其中的機制尚未釐清。有鑑於我們先前的研究結果顯示培養在基底膜上的細胞其RhoA活性低於培養在塑膠盤上的細胞。在此，我們探討RhoA/ Rho激酶路徑對泌乳激素訊息傳遞的影響。在本篇研究中，我們首先證實細胞的附著物可以影響乳腺上皮細胞泌乳激素接受器mRNA的表現，當細胞培養在基底膜上時具有較高泌乳激素接受器mRNA的表現。除此之外，我們利用帶有L63RhoA的腺病毒感染細胞，提高培養在基底膜上乳腺細胞RhoA的活性。實驗結果顯示，強迫使其RhoA活性上升，可以明顯地抑制泌乳激素接受器mRNA的表現量、STAT5的酪胺酸磷酸化以及最終乙型酪蛋白的基因表現。相反地，當我們利用dominant negative RhoA（N19RhoA）來降低培養在塑膠盤上細胞RhoA的活性，可以促進乳腺細胞泌乳激素接受器mRNA的表現與 STAT5酪胺酸磷酸化。接著，我們更進一步利用dominant negative ROK與抑制劑Y27632來降低RhoA下游分子ROK的活性，可得到類似於N19RhoA的結果。最後，我們也發現Y27632可以促進培養在塑膠盤上乳腺上皮細胞的Rac活性。因此，這些結果證實RhoA/ Rho激酶路徑至少在某種程度上為培養在塑膠盤上乳腺上皮細胞不利於泌乳激素訊息傳遞的原因之ㄧ。

關鍵字

細胞外基質 ； 泌乳激素 ； 乳腺上皮細胞

並列摘要

Optimal prolactin signaling in mammary epithelial cells requires cell adhesion to basement membrane. However, the underlying mechanism remains obscure. Here we investigate into the role of the RhoA/Rho kinase (ROK) pathway in the regulation of prolactin signaling since lower RhoA activity has been detected in mammary cells cultured on basement membrane compared to those cultured on plastic. Firstly, we have demonstrated that expression of prolactin receptor mRNA is influenced by substrata. Cells cultured on basement membrane exhibit higher level of prolactin receptor mRNA. Furthermore, overexpression of activated RhoA (L63RhoA) in cells cultured on basement membrane reduces prolactin receptor mRNA level, prolactin-induced Stat5 tyrosine phosphorylation and the downstream β-casein gene expression. On the contrary, overexpression of dominant negative RhoA (N19RhoA) in cells cultured on plastic results in the elevation in levels of prolactin receptor mRNA and of Stat5 phosphorylation. Similar results were obtained by expressing dominant negative ROK and application of the ROK inhibitor Y27632 in these cells. Inclusion of Y27632 in cells cultured on plastic also exerts a positive effect on Rac activity, leading to an increase in Rac activity. Thus, the RhoA/ROK pathway is, at least in part, responsible for the inefficiency of prolactin signaling in mammary cells cultured on plastc.

並列關鍵字

extracellular matrix ； prolactin ； mammary gland

參考文獻

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