| Autor: |
Bartley SC; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Proctor MT; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Xia H; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Ho E; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Kang DS; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Schuster K; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Bicca MA; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Seckler HS; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA., Viola KL; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA., Patrie SM; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA., Kelleher NL; Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA., De Mello FG; Instituto de Biofísica Carlos Chagas Filho (IBCCF), Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil., Klein WL; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.; Mesulam Center for Cognitive Neurology and Alzheimer's Disease, Northwestern University, Chicago, IL 60611, USA. |
| Abstrakt: |
Human amyloid beta peptide (Aβ) is a brain catabolite that at nanomolar concentrations can form neurotoxic oligomers (AβOs), which are known to accumulate in Alzheimer's disease. Because a predisposition to form neurotoxins seems surprising, we have investigated whether circumstances might exist where AβO accumulation may in fact be beneficial. Our investigation focused on the embryonic chick retina, which expresses the same Aβ as humans. Using conformation-selective antibodies, immunoblots, mass spectrometry, and fluorescence microscopy, we discovered that AβOs are indeed present in the developing retina, where multiple proteoforms are expressed in a highly regulated cell-specific manner. The expression of the AβO proteoforms was selectively associated with transiently expressed phosphorylated Tau (pTau) proteoforms that, like AβOs, are linked to Alzheimer's disease (AD). To test whether the AβOs were functional in development, embryos were cultured ex ovo and then injected intravitreally with either a beta-site APP-cleaving enzyme 1 (BACE-1) inhibitor or an AβO-selective antibody to prematurely lower the levels of AβOs. The consequence was disrupted histogenesis resulting in dysplasia resembling that seen in various retina pathologies. We suggest the hypothesis that embryonic AβOs are a new type of short-lived peptidergic hormone with a role in neural development. Such a role could help explain why a peptide that manifests deleterious gain-of-function activity when it oligomerizes in the aging brain has been evolutionarily conserved. |
