Characterization of an amyloid precursor protein-binding protein Fe65L2 and its novel isoforms lacking phosphotyrosine-interaction domains

Biochem J. 2002 Nov 1;367(Pt 3):687-95. doi: 10.1042/BJ20020562.

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.

MeSH terms

  • Alternative Splicing
  • Amyloid beta-Protein Precursor / metabolism*
  • Apoptosis
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Phosphoproteins / chemistry
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Polymerase Chain Reaction
  • Precipitin Tests
  • RNA, Messenger / genetics
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Transcriptional Activation

Substances

  • APBB3 protein, human
  • Amyloid beta-Protein Precursor
  • Carrier Proteins
  • Phosphoproteins
  • RNA, Messenger
  • Recombinant Proteins