Identification of functional roles and signaling pathways induced by toll-like receptors on chicken heterophils /
Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA), which are found in the cell walls of Gram-negative and Gram-positive bacteria, respectively. The purpose of the following studies was to determine if TLR...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2003.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=764887761&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA), which are found in the cell walls of Gram-negative and Gram-positive bacteria, respectively. The purpose of the following studies was to determine if TLRs are present on chicken heterophils and to evaluate the role that they may play in mediating oxidative burst. Anti-TLR antibodies were utilized to neutralize LPS- and LTA-stimulated oxidative burst. TLR 2 and 4 were found to mediate LPS-stimulated oxidative burst while CD14 and TLR2 mediate LTA-stimulated oxidative burst. RT-PCR and Western blotting were then employed to determine if TLR2 mRNA and protein were present in chicken heterophils. TLR2 mRNA and protein were detected providing additional evidence for the presence of TLR2 on chicken heterophils. Following the discovery of TLR2 mRNA and protein on chicken heterophils we elected to determine which signaling pathways are involved in TLR-mediated oxidative burst. Genistein (a tyrosine kinase inhibitor), verapamil (a calcium channel blocker), chelerythrine (a protein kinase C inhibitor), and pertussis toxin (a G-protein inhibitor) were used to determine the signaling pathway involved in LPS- and LTA-mediated oxidative burst. These findings demonstrated that distinct signal transduction pathways differentially regulate the stimulation of oxidative burst in avian heterophils. Pertussis toxin-sensitive, protein kinase C-dependent, Ca⁺⁺-dependent G proteins appear to regulate oxidative burst of avian heterophils stimulated with the Gram-negative agonist LPS; whereas, a protein kinase C-dependent signal transduction pathway plays the major role activating the oxidative burst of avian heterophils stimulated with Gram-positive agonists. To learn more about the TLR2 signaling pathway, we used selective pharmacological inhibitors to investigate the roles of phosphatidylinositol-3'-kinase (PI3-K), phospholipase C (PLC), calcium dependent protein kinase C (PKC), extra-cellular signal regulated kinase (ERK), and nuclear translocation factor-[K]B (NF-[K]B) on TLR2-mediated oxidative burst. U-73122 (a PLC inhibitor), wortmannin (a PI3-K inhibitor), PD 98059 (an ERK inhibitor), G[o] 6976 (a PKC inhibitor) and Bay 11-7082 (a NF-[K]B inhibitor) significantly decreased LTA-stimulated oxidative burst in heterophils. The data demonstrate that activated TLR2 utilizes a PI3-K->PLC->PKC->ERK->NF-[K]B signaling pathway that mediates the TLR-stimulated oxidative burst of chicken heterophils. |
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| Item Description: | Vita. "Major Subject: Veterinary Microbiology". |
| Physical Description: | xi, 95 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 82-93). |