title: Characterization of an amyloid precursor protein-binding protein Fe65L2 and its novel isoforms lacking phosphotyrosine-interaction domains.
abstract: Human Fe65L2 is a member of the Fe65 protein family, which interacts with amyloid precursor protein (APP). Fe65L2 contains an N-terminal WW (Trp-Trp) domain followed by two phosphotyrosine-interaction domains, and consists of 486 amino acids. In the present study, we cloned and characterized two novel isoforms of Fe65L2, designated I-214 and I-245, which are produced by alternative splicing of the RNA. The splicing events disrupt the ability to bind with APP and low-density-lipoprotein-receptor-related protein. Fe65L2 was highly expressed in the brain, whereas I-214 and I-245 were expressed in various tissues. In HEK-293 cells, Fe65L2 was expressed in the nucleus and cytosol, whereas I-245 and I-214 were localized exclusively to the nucleus. The ratio of I-214 to Fe65L2 mRNA was increased by apoptotic stimuli. Although the overexpression of either Fe65L2 or I-214 did not significantly affect the half-life and maturation of APP, or the secretion of secreted APP, the secretion of beta-amyloid peptide (Abeta)40 and Abeta42 was increased by overexpression of Fe65L2, but not by that of I-214. These results suggest that Fe65L2 affects Abeta production and a possible regulation of Fe65L2 function by alternative splicing.
authors.affiliation: Division of Demyelinating Disease and Aging, National Institute of Neuroscience, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan. Tanahash@ncnp.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanahashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tabira
mesh_terms: D017398:Alternative Splicing; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D017209:Apoptosis; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: C484721:APBB3 protein, human; D016564:Amyloid beta-Protein Precursor; D002352:Carrier Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D011994:Recombinant Proteins