Alterations in Granule Matrix and Cell Surface of Focal Adhesion Kinase-Deficient Mast Cells

Abstract

Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase that plays an important role in many cellular processes and is tyrosine phosphorylated after FcεRI aggregation in mast cells. In mice, null mutation of the fak gene results in a lethal phenotype in which the embryos fail to develop past day 8.5 of gestation. To study the role of FAK in these mast cells, 8.5-day embryos were isolated and placed in culture with IL-3 and stem cell factor (SCF). Although FAK was not required for the development of mast cells in culture, the FAK−/− embryo-derived mast cells had several distinct characteristics. Compared with the controls, the mast cells that lack FAK were less metachromatic and by electron microscopy had granules that appeared largely electron lucid, although their histamine content was unchanged. The FAK-deficient mast cells had a reduction in the content of chondroitin/dermatan sulfate, the major glycosaminoglycan component of the granular matrix. The FAK-deficient cells had fewer microvilli that were fused with each other, giving the cell surface a ruffled appearance. There was also a 3-fold increase in the number of cells highly expressing β7 integrin. However, signal transduction from the high affinity IgE receptor for the secretion of histamine was similar in the wild-type, heterozygote, and the FAK-deficient cells. The FcεRI-induced tyrosine phosphorylation of paxillin, Crk-associated tyrosine kinase substrate (CAS), and mitogen-activated protein kinase proteins was independent of FAK. These results indicate that FAK plays a role in regulating the glycosaminoglycan content of the secretory granules and influences the cell surface morphology of mast cells.

Identification and characterization of undifferentiated mast cells in mouse bone marrow

“…Unfractionated bone marrow was used as a positive control, and cells incubated without primary antibody served as negative controls for immunolabeling experiments. Samples for transmission electron microscopy were prepared as previously described, 17 and examined with a Phillips 108 electron microscope (FEI, Einhoven, The Netherlands). All images were prepared for publication using Adobe Photoshop 7.0 (Adobe Systems, San Jose, CA).…”

Difference in Cell Proliferation and Spontaneous Mediator Release Between Two Mast Cell Lines, NCL-2 and RBL-2H3 on Honey Comb-like Structured Film

“…Thus, different materials, structures, surface topologies, and hardness's constitute the physical factors in culture substrates that influence cells [33,34]. In addition, when cells adhere to the culture substrate, cell information is transferred through integrins [17,35,36]. In particular, Focal Adhesion Kinase (FAK) transmits integrin-and/or receptor-dependent signals, leading to the control of cell motility, adherence, proliferation, and the prevention of cell from activating the apoptotic process [35].…”

TLR4 Activation Promotes the Secretion of IL-8 Which Enhances the Invasion and Proliferation of Endometrial Stromal Cells in an Autocrine Manner via the FAK Signal Pathway

“…Overexpression of FAK also appears to be involved in both altering apoptotic signaling and mediating malignant transformation. FAK‐deficient cells have been reported to spread more slowly on extracellular matrix proteins, exhibit more focal adhesions, and migrate poorly in response to chemotactic signals . Moreover, attenuating FAK expression has been reported to induce apoptosis in tumor cells .…”