Evidence for a Role for SAM68 in the Responses of Human Neutrophils to Ligation of CD32 and to Monosodium Urate Crystals

• Published in: The Journal of immunology (1950) Vol. 166; no. 7; pp. 4664 - 4671
• Main Authors: Gilbert, Caroline, Barabe, Frederic, Rollet-Labelle, Emmanuelle, Bourgoin, Sylvain G, McColl, Shaun R, Damaj, Bassam B, Naccache, Paul H
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.04.2001
• Subjects: Adaptor Proteins, Signal Transducing; Adult; CD32 antigen; Crystallization; DNA-Binding Proteins; Humans; Isoflurophate - pharmacology; Ligands; Microspheres; monosodium urate; Neutrophils - drug effects; Neutrophils - enzymology; Neutrophils - immunology; Neutrophils - metabolism; Phagocytosis - drug effects; Phosphorylation - drug effects; Poly U - metabolism; Precipitin Tests; Protease Inhibitors - pharmacology; Protein Binding - drug effects; Protein Binding - immunology; Receptors, IgG - immunology; Receptors, IgG - metabolism; RNA-Binding Proteins - isolation & purification; RNA-Binding Proteins - metabolism; RNA-Binding Proteins - physiology; SAM68 protein; Signal Transduction - drug effects; Signal Transduction - immunology; Subcellular Fractions - drug effects; Subcellular Fractions - enzymology; Subcellular Fractions - metabolism; Tyrosine - metabolism; Up-Regulation - immunology; Uric Acid - pharmacology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.166.7.4664

SAM68 (Src-associated in mitosis 68 kDa) is a member of the signal transduction of activator RNA novel gene family coding for proteins postulated to be involved in signal transduction and activation of RNA. It has been implicated through its phosphorylation status in the control of the transition from the G(1) to the S phases during mitosis. However, the implication and role of SAM68 in nonproliferative cells are unknown. The present study was initiated to examine the role of SAM68 in the phagocytic responses of the terminally differentiated human neutrophils. The results obtained show that SAM68 is present in human neutrophils and that it is tyrosine phosphorylated in response to stimulation by monosodium urate crystals or by ligation of CD32. Stimulation of neutrophils by these agonists decreases the association of SAM68 with Sepharose-conjugated poly-U beads. Additionally, the amount of immunoprecipitable SAM68 was modulated differentially after stimulation by monosodium urate crystals or by CD32 engagement indicating that the posttranslational modifications and/or protein associations of SAM68 induced by these two agonists differed. The results of this study provide evidence for an involvement of SAM68 in signal transduction by phagocytic agonists in human neutrophils and indicate that SAM68 may play a role in linking the early events of signal transduction to the posttranscriptional modulation of RNA.