Differential binding of apolipoprotein E isoforms to tau and other cytoskeletal proteins

Lynne M. Fleming, Karl H. Weisgraber, Warren J. Strittmatter, Juan C Troncoso, Gail V W Johnson

Research output: Contribution to journalArticle

Abstract

The apolipoprotein E4 (apoE4) gene dose is a major risk factor for late-onset and sporadic Alzheimer's disease with 50% of homozygous patients developing the disease by age 70. Previous studies have shown localization of apoE to the cytoplasm of certain neurons within the brain. In addition, apoE3, but not apoE4, forms SDS-stable complexes with the microtubule-associated proteins tau and MAP-2. To extend these studies and quantitate the association of apoE with other proteins, the association of apoE3 and apoE4 with several cytoskeletal proteins was examined using both gel shift and overlay assays. In the gel shift assay, apoE3 formed SDS-stable complexes with the longest isoform of human recombinant tau (T4L), the shortest isoform of human recombinant tau (T3), and the 160-kDa neurofilament protein (NFM). ApoE4 did not bind T3, T4L, or NFM in this assay. The association of apoE3 and apoE4 with T4L, actin, or tubulin was further examined in an overlay assay with known amounts of the cytoskeletal proteins slot-blotted onto nitrocellulose and incubated in 0.15 μM (5 μg/ml) apoE3 or apoE4. In this assay, apoE3 and apoE4 bound T4L and tubulin equally well. In contrast, apoE3 bound actin with a significantly greater affinity than did apoE4. These results indicate that apoE isoforms interact with cytoskeletal proteins with at least two different binding affinities. The more avid interaction results in the formation of complexes which are SDS stable and occurs almost exclusively with apoE3, while the other interactions between apoE and cytoskeletal proteins are not specific for apoE3.

Original languageEnglish (US)
Pages (from-to)252-260
Number of pages9
JournalExperimental Neurology
Volume138
Issue number2
DOIs
StatePublished - Apr 1996

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Apolipoprotein E3
Apolipoprotein E4
Cytoskeletal Proteins
Apolipoproteins E
Protein Isoforms
Neurofilament Proteins
Tubulin
Actins
Gels
Microtubule-Associated Proteins
Collodion
Alzheimer Disease
Cytoplasm
Neurons

ASJC Scopus subject areas

  • Neurology
  • Neuroscience(all)

Cite this

Differential binding of apolipoprotein E isoforms to tau and other cytoskeletal proteins. / Fleming, Lynne M.; Weisgraber, Karl H.; Strittmatter, Warren J.; Troncoso, Juan C; Johnson, Gail V W.

In: Experimental Neurology, Vol. 138, No. 2, 04.1996, p. 252-260.

Research output: Contribution to journalArticle

Fleming, Lynne M. ; Weisgraber, Karl H. ; Strittmatter, Warren J. ; Troncoso, Juan C ; Johnson, Gail V W. / Differential binding of apolipoprotein E isoforms to tau and other cytoskeletal proteins. In: Experimental Neurology. 1996 ; Vol. 138, No. 2. pp. 252-260.
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