title: Selective induction of alternatively spliced FynT isoform by TNF facilitates persistent inflammatory responses in astrocytes.
abstract: Fyn tyrosine kinase has been implicated in the pathogenesis of Alzheimer's disease (AD). We have previously reported that upregulation of the FynT isoform in AD brains was partly associated with astrocyte activation. In this study, we demonstrated selective FynT induction in murine cortex and primary astrocyte culture after prolonged exposure to inflammatory stimulants, suggesting that FynT may mediate persistent neuroinflammation. To delineate the functional role of astrocytic FynT in association with TNF-mediated inflammatory responses, immortalized normal human astrocytes (iNHA) stably expressing FynT kinase constitutively active (FynT-CA) or kinase dead (FynT-KD) mutants were treated with TNF and compared for inflammatory responses using high-throughput real-time RT-PCR and Luminex multi-analyte immunoassays. FynT-CA but not FynT-KD mutant exhibited drastic induction of proinflammatory cytokines and chemokines after prolonged exposure to TNF, which could be attenuated by treating with Fyn kinase inhibitor PP2 or silencing via FynT-specific DsiRNA. FynT kinase activity-dependent induction of PKCδ expression, PKCδ phosphorylation, as well as NFκB activation was detected at the late phase but not the early phase of TNF signaling. In conclusion, selective FynT induction by TNF may facilitate persistent inflammatory responses in astrocytes, which is highly relevant to chronic neuroinflammation in neurodegenerative diseases including but not limited to AD.
authors.affiliation: Department of Clinical Translational Research, Singapore General Hospital, The Academia, Level 9, Discovery Tower, 20 College Road, 169856, Singapore.|Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge 117599, Singapore.
authors.forename: Chingli
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Clinical Translational Research, Singapore General Hospital, The Academia, Level 9, Discovery Tower, 20 College Road, 169856, Singapore.
authors.forename: Clara Y B
authors.initials: CY
authors.lastname: Low
authors.affiliation: Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge 117599, Singapore.
authors.forename: Siew Ying
authors.initials: SY
authors.lastname: Wong
authors.affiliation: Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge 117599, Singapore.
authors.forename: Mitchell K P
authors.initials: MK
authors.lastname: Lai
authors.affiliation: Department of Clinical Translational Research, Singapore General Hospital, The Academia, Level 9, Discovery Tower, 20 College Road, 169856, Singapore.|Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge 117599, Singapore.
authors.forename: Michelle G K
authors.initials: MG
authors.lastname: Tan
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D015415:Biomarkers; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D007249:Inflammation / Q000235:genetics* / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000235:genetics; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D048069:Tumor Necrosis Factors / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators; D016328:NF-kappa B; D048069:Tumor Necrosis Factors; D051076:Proto-Oncogene Proteins c-fyn; D051745:Protein Kinase C-delta