Cell chemotaxis plays a pivotal role in normal development, inflammatory response, injury repair and tissue regeneration in all organisms. It is also a critical contributor to cancer metastasis, altered angiogenesis and neurite growth in disease. The molecular mechanisms regulating chemotaxis are currently being identified and key components may be pertinent therapeutic targets. Although these components appear to be mostly common in various cells, there are important differences in chemotactic signaling networks and signal processing that result in the distinct chemotactic behavior of mesenchymal cells compared to much better studied amoeboid blood cells. These differences are not necessarily predetermined based on cell type, but are rather chosen and exploited by cells to modify their chemotactic behavior based on physical constraints and/or environmental conditions. This results in a specific type of chemotactic migration in mesenchymal cells that can be selectively targeted in disease. Here, we compare the chemotactic behavior, signaling and motility of mesenchymal and amoeboid cells. We suggest that the current model of chemotaxis is applicable for small amoeboid cells but needs to be reconsidered for large mesenchymal cells. We focus on new candidate regulatory molecules and feedback mechanisms that may account for mesenchymal cell type-specific chemotaxis.
Keywords: Chemotaxis; Feedback regulation; Fibroblasts; GEFs, guanine nucleotide exchange factors; GPCRs, G-protein coupled receptors; Hydrogen peroxide; LEGI, local excitation and global inhibition; MAP-kinase, mitogen-activated protein kinase; NOX, NADPH-oxidase; PDGF, platelet derived growth factor; PI3-kinase, phosphatidylinositol-3-kinase; PIP3, phosphatidylinositol (3,4,5)-trisphosphate; PLA2, phospholipase A2; PTEN, phosphatase and tensin homolog; RTKs, receptor tyrosine kinases; Signaling; mTORC, mechanistic target of rapamycin complex; РТР-1В, protein tyrosine phosphatase-1B.