Lund A W, Stegemann J P, Plopper G E
Department of Biology, Rensselaer Polytechnic Institute, Troy, NY.
Open Stem Cell J. 2009;1:40-53. doi: 10.2174/1876893800901010040.
The extracellular matrix provides structural and organizational cues for tissue development and defines and maintains cellular phenotype during cell fate determination. Multipotent mesenchymal stem cells use this matrix to tightly regulate the balance between their differentiation potential and self-renewal in the native niche. When understood, the mechanisms that govern cell-matrix crosstalk during differentiation will allow for efficient engineering of natural and synthetic matrices to specifically direct and maintain stem cell phenotype. This work identifies the discoidin domain receptor 1 (DDR1), a collagen activated receptor tyrosine kinase, as a potential link through which stem cells sense and respond to the 3D organization of their extracellular matrix microenvironment. DDR1 is dependent upon both the structure and proteolytic state of its collagen ligand and is specifically expressed and localized in three dimensional type I collagen culture. Inhibition of DDR1 expression results in decreased osteogenic potential, increased cell spreading, stress fiber formation and ERK1/2 phosphorylation. Additionally, loss of DDR1 activity alters the cell-mediated organization of the naïve type I collagen matrix. Taken together, these results demonstrate a role for DDR1 in the stem cell response to and interaction with three dimensional type I collagen. Dynamic changes in cell shape in 3D culture and the tuning of the local ECM microstructure, directs crosstalk between DDR1 and two dimensional mechanisms of osteogenesis that can alter their traditional roles.
细胞外基质为组织发育提供结构和组织线索,并在细胞命运决定过程中定义和维持细胞表型。多能间充质干细胞利用这种基质在天然微环境中严格调节其分化潜能和自我更新之间的平衡。一旦了解了分化过程中细胞与基质相互作用的机制,就能够有效地设计天然和合成基质,以特异性地引导和维持干细胞表型。这项研究确定了盘状结构域受体1(DDR1),一种胶原激活的受体酪氨酸激酶,作为干细胞感知和响应其细胞外基质微环境三维结构的潜在联系。DDR1依赖于其胶原配体的结构和蛋白水解状态,并在三维I型胶原培养中特异性表达和定位。抑制DDR1表达会导致成骨潜能降低、细胞铺展增加、应力纤维形成和ERK1/2磷酸化。此外,DDR1活性丧失会改变幼稚I型胶原基质的细胞介导组织。综上所述,这些结果证明了DDR1在干细胞对三维I型胶原的反应和相互作用中的作用。三维培养中细胞形状的动态变化以及局部细胞外基质微观结构的调节,指导了DDR1与二维成骨机制之间的相互作用,这可能会改变它们的传统作用。