The MEK-ERK signaling pathway is a negative regulator of cartilage-specific gene expression in embryonic limb mesenchyme
The MEK-ERK signaling pathway is a negative regulator of cartilage-specific gene expression in embryonic limb mesenchyme
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DOI：
10.1074/jbc.m309805200
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发表时间：
2004-02-06
影响因子：
4.8
通讯作者：
Kulyk, WM
中科院分区：
文献类型：
--
作者：
Bobick, BE;Kulyk, WM
细胞外信号调节激酶（ERK）丝裂原活化蛋白激酶途径，也称为MEK-ERK激酶级联，最近已涉及胚胎软骨分化的调节。然而，它在这一复杂过程中的确切作用仍有争议。为了更彻底地研究MEK-ERK激酶级联在软骨形成中的作用，我们分析了两种结构不同的MEK药理学抑制剂（ERK的上游激酶激活剂）对鸡胚肢体间充质细胞微团培养物中软骨细胞分化的影响。我们发现，MEK抑制剂，U 0126和PD 98059，促进软骨特征的mRNA转录的II型胶原蛋白，聚集蛋白聚糖，和转录因子，Sox 9的积累增加。PD 98059处理刺激硫酸化糖胺聚糖增加沉积到阿辛蓝-软骨基质和周围培养基中，而U 0126升高糖胺聚糖分泌到单独的培养基组分中。这两种MEK抑制剂增加了总II型胶原蛋白在微团培养物中的积累，并提高了转染的II型胶原增强子-荧光素酶报告基因的活性。因此，药理学MEK抑制诱导多种软骨细胞分化标志物的表达增加。相反，肢体间充质细胞与组成型活性的MEK 1质粒的转染导致显着降低共转染的II型胶原增强子-荧光素酶报告基因的活性。总的来说，这些研究结果支持的假设，通过MEK-ERK激酶级联信号可能作为一个重要的抑制调节胚胎软骨分化。
The extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase pathway, also known as the MEK-ERK kinase cascade, has recently been implicated in the regulation of embryonic cartilage differentiation. However, its precise role in this complex process remains controversial. To more thoroughly examine the role of the MEK-ERK kinase cascade in chondrogenesis, we analyzed the effects of two structurally different pharmacological inhibitors of MEK, the upstream kinase activator of ERK, on chondrocyte differentiation in micromass cultures of embryonic chick limb mesenchyme cells. We found that the MEK inhibitors, U0126 and PD98059, promote increased accumulation of cartilage-characteristic mRNA transcripts for type II collagen, aggrecan, and the transcription factor, Sox9. PD98059 treatment stimulated increased deposition of sulfated glycosaminoglycan into both Alcian blue-stainable cartilage matrix and the surrounding culture medium, whereas U0126 elevated glycosaminoglycan secretion into the medium fraction alone. Both MEK inhibitors increased total type II collagen protein accumulation in micromass culture and elevated the activity of a transfected type II collagen enhancer-luciferase reporter gene. Thus, pharmacological MEK inhibition induced increased expression of multiple chondrocyte differentiation markers. Conversely, transfection of limb mesenchyme cells with a constitutively active MEK1 plasmid resulted in a prominent decrease in the activity of a co-transfected type II collagen enhancer-luciferase reporter gene. Collectively, these findings support the hypothesis that signaling through the MEK-ERK kinase cascade may function as an important inhibitory regulator of embryonic cartilage differentiation.