title: TAM receptors are dispensable in the phagocytosis and killing of bacteria.
abstract: Many receptors that are employed for the engulfment of apoptotic cells are also used for the recognition and phagocytosis of bacteria. Tyro3, Axl, and Mertk (TAM) are important in the phagocytosis of apoptotic cells by macrophages. Animals lacking these receptors are hypersensitive to bacterial products. In this report, we examine whether the TAM receptors are involved in the phagocytosis of bacteria. We found that macrophages lacking Mertk, Axl, Tyro3 or all three receptors were equally efficient in the phagocytosis of Gram-negative E. coli. Similarly, the phagocytosis of E. coli and Gram-positive S. aureus bioparticles by macrophages lacking TAM receptors was equal to wild-type. In addition, we found that Mertk did not play a role in killing of extracellular E. coli or the replication status of intracellular Francisella tularensis. Thus, while TAM receptors may regulate signal transduction to bacterial components, they are not essential for the phagocytosis and killing of bacteria.
authors.affiliation: Curriculum in Oral Biology, UNC Neuroscience Center CB#7250, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Williams
authors.forename: Robin R
authors.initials: RR
authors.lastname: Craven
authors.forename: H Shelton
authors.initials: HS
authors.lastname: Earp
authors.forename: Tom H
authors.initials: TH
authors.lastname: Kawula
authors.forename: Glenn K
authors.initials: GK
authors.lastname: Matsushima
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology; D005604:Francisella tularensis / Q000254:growth & development / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D015513:Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology*; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D020794:Receptor Protein-Tyrosine Kinases / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction; D013047:Specific Pathogen-Free Organisms; D014406:Tularemia / Q000276:immunology; D000076202:c-Mer Tyrosine Kinase; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; C490767:Mertk protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; C513478:Tyro3 protein, mouse; D000076202:c-Mer Tyrosine Kinase; D000094963:Axl Receptor Tyrosine Kinase