title: 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 FcepsilonRI 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 beta(7) 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 FcepsilonRI-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.
authors.affiliation: Receptors and Signal Transduction Section, Oral Infection and Immunity Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vial
authors.forename: Constance
authors.initials: C
authors.lastname: Oliver
authors.forename: Maria Célia
authors.initials: MC
authors.lastname: Jamur
authors.forename: Maria Verônica Dávila
authors.initials: MV
authors.lastname: Pastor
authors.forename: Edvaldo
authors.initials: E
authors.lastname: da Silva Trindade
authors.forename: Elsa
authors.initials: E
authors.lastname: Berenstein
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Reuben P
authors.initials: RP
authors.lastname: Siraganian
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006025:Glycosaminoglycans / Q000378:metabolism; D007073:Immunoglobulin E / Q000502:physiology; D039641:Integrin beta Chains / Q000096:biosynthesis; D008297:Male; D008407:Mast Cells / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050737:Proto-Oncogene Proteins c-crk; D017455:Receptors, IgE / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; D006025:Glycosaminoglycans; D039641:Integrin beta Chains; D051419:Paxillin; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; C496062:Pxn protein, mouse; D017455:Receptors, IgE; C091368:integrin beta7; D007073:Immunoglobulin E; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse