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Self-association of the APC tumor suppressor is required for the assembly, stability, and activity of the Wnt signaling destruction complex.

Kunttas-Tatli E, Roberts DM, McCartney BM - Mol. Biol. Cell (2014)

Bottom Line: The destruction complex forms macromolecular particles we termed the destructosome.Here we show that a novel N-terminal coil, the APC self-association domain (ASAD), found in vertebrate and invertebrate APCs, directly mediates self-association of Drosophila APC2 and plays an essential role in the assembly and stability of the destructosome that regulates β-cat degradation in Drosophila and human cells.These results suggest that APC proteins are required not only for the activity of the destructosome, but also for the assembly and stability of this macromolecular machine.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.

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The ASAD is a conserved N-terminal coil. (A) Schematic representation of human APC and Drosophila APC2. ANS2, actin nucleation sequence 2; Arm repeats, Armadillo repeats (blue); ASAD, APC self-association domain (orange); MCR, mutation cluster region; 15Rs, 15–amino acid repeats (pink); 20Rs, 20–amino acid repeats (purple). (B) Sequence alignment of ASAD between human, Xenopus, and Drosophila APC proteins (*identical; [:], conserved substitution; [.], semiconserved substitution). (C) The ASAD coil fits into the classic heptad repeat (abcdefg) motif, where a and d are hydrophobic, e and g are charged, and b, c, and f tend to be polar amino acids (Gruber and Lupas, 2003). The four residues changed to proline in the APC2-ASADPro mutant are indicated.
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Figure 1: The ASAD is a conserved N-terminal coil. (A) Schematic representation of human APC and Drosophila APC2. ANS2, actin nucleation sequence 2; Arm repeats, Armadillo repeats (blue); ASAD, APC self-association domain (orange); MCR, mutation cluster region; 15Rs, 15–amino acid repeats (pink); 20Rs, 20–amino acid repeats (purple). (B) Sequence alignment of ASAD between human, Xenopus, and Drosophila APC proteins (*identical; [:], conserved substitution; [.], semiconserved substitution). (C) The ASAD coil fits into the classic heptad repeat (abcdefg) motif, where a and d are hydrophobic, e and g are charged, and b, c, and f tend to be polar amino acids (Gruber and Lupas, 2003). The four residues changed to proline in the APC2-ASADPro mutant are indicated.

Mentions: In addition, APC self-association may contribute to both destruction complex function and dysfunction (Kunttas-Tatli et al., 2012). Vertebrate APC (vAPC) can self-associate via multiple mechanisms and domains. However, the precise role of APC self-association in normal destruction complex function and the affects this has on cancer initiation and progression are unclear. Two self-association domains C-terminal to the Armadillo (Arm) repeats in vAPC have been clearly implicated in APC's normal cytoskeletal functions. The dimerization coil ANS2 (Figure 1A) within the basic domain is required for APC's actin nucleation function (Okada et al., 2010), whereas a second oligomerization domain (OD-2; Figure 1A) can modulate the clustering of APC at microtubule plus ends at the tips of membrane protrusions (Li et al., 2008). N-terminal to the Arm repeats, vAPC can form coiled-coil–based dimers through an N-terminal coil (OD-1; Figure 1A), but the precise role of OD-1 in normal APC function is not well understood. The presence of multiple self-association sites within vAPC suggests that the protein may have the ability to form large oligomers in addition to dimers, although it is not clear whether this occurs in vivo.


Self-association of the APC tumor suppressor is required for the assembly, stability, and activity of the Wnt signaling destruction complex.

Kunttas-Tatli E, Roberts DM, McCartney BM - Mol. Biol. Cell (2014)

The ASAD is a conserved N-terminal coil. (A) Schematic representation of human APC and Drosophila APC2. ANS2, actin nucleation sequence 2; Arm repeats, Armadillo repeats (blue); ASAD, APC self-association domain (orange); MCR, mutation cluster region; 15Rs, 15–amino acid repeats (pink); 20Rs, 20–amino acid repeats (purple). (B) Sequence alignment of ASAD between human, Xenopus, and Drosophila APC proteins (*identical; [:], conserved substitution; [.], semiconserved substitution). (C) The ASAD coil fits into the classic heptad repeat (abcdefg) motif, where a and d are hydrophobic, e and g are charged, and b, c, and f tend to be polar amino acids (Gruber and Lupas, 2003). The four residues changed to proline in the APC2-ASADPro mutant are indicated.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4214788&req=5

Figure 1: The ASAD is a conserved N-terminal coil. (A) Schematic representation of human APC and Drosophila APC2. ANS2, actin nucleation sequence 2; Arm repeats, Armadillo repeats (blue); ASAD, APC self-association domain (orange); MCR, mutation cluster region; 15Rs, 15–amino acid repeats (pink); 20Rs, 20–amino acid repeats (purple). (B) Sequence alignment of ASAD between human, Xenopus, and Drosophila APC proteins (*identical; [:], conserved substitution; [.], semiconserved substitution). (C) The ASAD coil fits into the classic heptad repeat (abcdefg) motif, where a and d are hydrophobic, e and g are charged, and b, c, and f tend to be polar amino acids (Gruber and Lupas, 2003). The four residues changed to proline in the APC2-ASADPro mutant are indicated.
Mentions: In addition, APC self-association may contribute to both destruction complex function and dysfunction (Kunttas-Tatli et al., 2012). Vertebrate APC (vAPC) can self-associate via multiple mechanisms and domains. However, the precise role of APC self-association in normal destruction complex function and the affects this has on cancer initiation and progression are unclear. Two self-association domains C-terminal to the Armadillo (Arm) repeats in vAPC have been clearly implicated in APC's normal cytoskeletal functions. The dimerization coil ANS2 (Figure 1A) within the basic domain is required for APC's actin nucleation function (Okada et al., 2010), whereas a second oligomerization domain (OD-2; Figure 1A) can modulate the clustering of APC at microtubule plus ends at the tips of membrane protrusions (Li et al., 2008). N-terminal to the Arm repeats, vAPC can form coiled-coil–based dimers through an N-terminal coil (OD-1; Figure 1A), but the precise role of OD-1 in normal APC function is not well understood. The presence of multiple self-association sites within vAPC suggests that the protein may have the ability to form large oligomers in addition to dimers, although it is not clear whether this occurs in vivo.

Bottom Line: The destruction complex forms macromolecular particles we termed the destructosome.Here we show that a novel N-terminal coil, the APC self-association domain (ASAD), found in vertebrate and invertebrate APCs, directly mediates self-association of Drosophila APC2 and plays an essential role in the assembly and stability of the destructosome that regulates β-cat degradation in Drosophila and human cells.These results suggest that APC proteins are required not only for the activity of the destructosome, but also for the assembly and stability of this macromolecular machine.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.

Show MeSH
Related in: MedlinePlus