| First Author | Hinson SR | Year | 2017 |
| Journal | Proc Natl Acad Sci U S A | Volume | 114 |
| Issue | 21 | Pages | 5491-5496 |
| PubMed ID | 28461494 | Mgi Jnum | J:242209 |
| Mgi Id | MGI:5904684 | Doi | 10.1073/pnas.1701960114 |
| Citation | Hinson SR, et al. (2017) Autoantibody-induced internalization of CNS AQP4 water channel and EAAT2 glutamate transporter requires astrocytic Fc receptor. Proc Natl Acad Sci U S A 114(21):5491-5496 |
| abstractText | Aquaporin-4 (AQP4) water channel-specific IgG distinguishes neuromyelitis optica (NMO) from multiple sclerosis and causes characteristic immunopathology in which central nervous system (CNS) demyelination is secondary. Early events initiating the pathophysiological outcomes of IgG binding to astrocytic AQP4 are poorly understood. CNS lesions reflect events documented in vitro following IgG interaction with AQP4: AQP4 internalization, attenuated glutamate uptake, intramyelinic edema, interleukin-6 release, complement activation, inflammatory cell recruitment, and demyelination. Here, we demonstrate that AQP4 internalization requires AQP4-bound IgG to engage an astrocytic Fcgamma receptor (FcgammaR). IgG-lacking Fc redistributes AQP4 within the plasma membrane and induces interleukin-6 release. However, AQP4 endocytosis requires an activating FcgammaR's gamma subunit and involves astrocytic membrane loss of an inhibitory FcgammaR, CD32B. Interaction of the IgG-AQP4 complex with FcgammaRs triggers coendocytosis of the excitatory amino acid transporter 2 (EAAT2). Requirement of FcgammaR engagement for internalization of two astrocytic membrane proteins critical to CNS homeostasis identifies a complement-independent, upstream target for potential early therapeutic intervention in NMO. |
