Cell elongation and differentiation has been shown to be modulated by topographical cues provided by grating substratum. However, little is known about the mechanisms and forces involved in the grating-induced cell elongation, due to the difficulty in fabricating soft elastic gels that allow 3-dimensional (3D) cell traction stress measurements. In this paper, we present a method to fabricate soft elastic polyacrylamide grating substrates, using an imprinted polyethylene terephthalate mould, for 3D cell traction stress measurements.
Yip Ai Kia
Physiologically, cells experience and respond to a variety of mechanical stimuli such as rigidity and topography of the extracellular matrix. However, little is known about the effects of substrate curvature on cell behavior. We developed a novel, to our knowledge, method to fabricate cell culture substrates with semicylindrical grooves of negative curvatures (radius of curvature, Rc = 20-100 μm). We found that negative substrate curvatures induced elongation of mesenchymal and epithelial cells along the cylinder axis.
MEKK1 (also known as MAP3K1), which plays a major role in MAPK signaling, has been implicated in mechanical processes in cells, such as migration. Here, we identify the actin-binding protein calponin-3 as a new MEKK1 substrate in the signaling that regulates actomyosin-based cellular contractility. MEKK1 colocalizes with calponin-3 at the actin cytoskeleton and phosphorylates it, leading to an increase in the cell-generated traction stress.
Oncogenic Ras induces cell transformation and promotes an invasive phenotype. The tumor suppressor p53 has a suppressive role in Ras-driven invasion. However, its mechanism remains to be poorly understood. Here we show that p53 induces activation of the mitochondrial protease high temperature requirement A2 (HtrA2; also known as Omi) and prevents Ras-driven invasion by modulating the actin cytoskeleton.
Tumor suppressor p53 prevents tumorigenesis and tumor growth by suppressing the activation of several transcription factors, including NF-κB and STAT3. On the other hand, p53 stimulates actin cytoskeleton remodeling and integrin related signaling cascades. Here, we examined the p53-mediated link between regulation of the actin cytoskeleton and activation of NF-κB and STAT3 in MCF-7 cells and mouse embryonic fibroblasts (MEFs). In the absence of p53, STAT3 was constitutively activated. This activation was attenuated by depleting the expression of p65, a component of NF-κB.