Cell crawling assisted by contractile stress induced retraction

Mechanochemical Signaling Directs Cell-Shape Change

For specialized cell function, as well as active cell behaviors such as division, migration, and tissue development, cells must undergo dynamic changes in shape. To complete these processes, cells integrate chemical and mechanical signals to direct force production. This mechanochemical integration allows for the rapid production and adaptation of leading-edge machinery in migrating cells, the invasion of one cell into another during cell-cell fusion, and the force-feedback loops that ensure robust cytokinesis. A quantitative understanding of cell mechanics coupled with protein dynamics has allowed us to account for furrow ingression during cytokinesis, a model cell-shape-change process. At the core of cell-shape changes is the ability of the cell's machinery to sense mechanical forces and tune the force-generating machinery as needed. Force-sensitive cytoskeletal proteins, including myosin II motors and actin cross-linkers such as α-actinin and filamin, accumulate in response to internally generated and externally imposed mechanical stresses, endowing the cell with the ability to discern and respond to mechanical cues. The physical theory behind how these proteins display mechanosensitive accumulation has allowed us to predict paralog-specific behaviors of different cross-linking proteins and identify a zone of optimal actin-binding affinity that allows for mechanical stress-induced protein accumulation. These molecular mechanisms coupled with the mechanical feedback systems ensure robust shape changes, but if they go awry, they are poised to promote disease states such as cancer cell metastasis and loss of tissue integrity.

Girdin, a regulator of cell motility, is a potential prognostic marker for esophageal squamous cell carcinoma

Girdin, an actin-binding Akt substrate, regulates actin reconstruction and Akt-dependent cell motility in fibroblasts and in a human breast cancer cell line. We examined whether Girdin is also involved in the motility of esophageal squamous cell carcinoma (ESCC) cells. Immunofluorescent staining and migration assays were performed, using KYSE cell lines, to examine whether Girdin is involved in the motility of ESCC cells. Upon EGF stimulation, Girdin colocalized with filamentous actin (F-actin) in the lamellipodia as determined by immunofluorescent staining. In migration assays, cell motility was significantly reduced in KYSE cell lines transfected with Girdin siRNA compared with the negative control. In addition, we examined the relationship between Girdin expression and clinical data, using specimens resected from ESCC patients. In immunohistochemical (IHC) analyses using specimens resected from ESCC patients, overall survival was significantly longer in cases showing lower Girdin expression compared to cases with higher Girdin expression. Collectively, Girdin appears to be involved in the motility of ESCC cells. The levels of Girdin expression correlated inversely with the survival of ESCC patients. Therefore, in ESCC, Girdin may be a prognostic marker and may serve as a therapeutic target as well.