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Defining desmosomal plakophilin-3 interactions.

Bonné S, Gilbert B, Hatzfeld M, Chen X, Green KJ, van Roy F - J. Cell Biol. (2003)

Bottom Line: We found that PKP3 binds all three desmogleins, desmocollin (Dsc) 3a and -3b, and possibly also Dsc1a and -2a.Evidence was found for the presence of at least two DP-PKP3 interaction sites.Together, these results show that PKP3, whose epithelial and epidermal desmosomal expression pattern and protein interaction repertoire are broader than those of PKP1 and -2, is a unique multiprotein binding element in the basic architecture of a vast majority of epithelial desmosomes.

View Article: PubMed Central - PubMed

Affiliation: Molecular Cell Biology Unit, Department for Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB)-Ghent University, B-9000 Ghent, Belgium.

ABSTRACT
Plakophilin 3 (PKP3) is a recently described armadillo protein of the desmosomal plaque, which is synthesized in simple and stratified epithelia. We investigated the localization pattern of endogenous and exogenous PKP3 and fragments thereof. The desmosomal binding properties of PKP3 were determined using yeast two-hybrid, coimmunoprecipitation and colocalization experiments. To this end, novel mouse anti-PKP3 mAbs were generated. We found that PKP3 binds all three desmogleins, desmocollin (Dsc) 3a and -3b, and possibly also Dsc1a and -2a. As such, this is the first protein interaction ever observed with a Dsc-b isoform. Moreover, we determined that PKP3 interacts with plakoglobin, desmoplakin (DP) and the epithelial keratin 18. Evidence was found for the presence of at least two DP-PKP3 interaction sites. This finding might explain how lateral DP-PKP interactions are established in the upper layers of stratified epithelia, increasing the size of the desmosome and the number of anchoring points available for keratins. Together, these results show that PKP3, whose epithelial and epidermal desmosomal expression pattern and protein interaction repertoire are broader than those of PKP1 and -2, is a unique multiprotein binding element in the basic architecture of a vast majority of epithelial desmosomes.

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Intracellular localization of exogenous GFP-tagged PKP3 fragments in COS1 cells. Full-length PKP3 localizes at sites of cell–cell contact, and cytoplasmic aggregates are also observed (a). PKP3arm and head fragments localize predominantly in nucleus (c) and cytoplasm (e), respectively. Control DAPI stainings are shown (b, d, and f). Bar, 10 μm.
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fig5: Intracellular localization of exogenous GFP-tagged PKP3 fragments in COS1 cells. Full-length PKP3 localizes at sites of cell–cell contact, and cytoplasmic aggregates are also observed (a). PKP3arm and head fragments localize predominantly in nucleus (c) and cytoplasm (e), respectively. Control DAPI stainings are shown (b, d, and f). Bar, 10 μm.

Mentions: Because COS cells were used in previous studies on PKP1 and PKP2 protein properties (Kowalczyk et al., 1999a; Chen et al., 2002), transfection experiments were repeated in this cell type. As shown in Fig. 5 , the intracellular localizations of full-length PKP3 (a and b), PKP3arm (c and d) and PKP3head (e and f) correspond with our observations made in MCF7/AZ, HCT8/E8 and PtK2 cells (unpublished observations in the latter cell type).


Defining desmosomal plakophilin-3 interactions.

Bonné S, Gilbert B, Hatzfeld M, Chen X, Green KJ, van Roy F - J. Cell Biol. (2003)

Intracellular localization of exogenous GFP-tagged PKP3 fragments in COS1 cells. Full-length PKP3 localizes at sites of cell–cell contact, and cytoplasmic aggregates are also observed (a). PKP3arm and head fragments localize predominantly in nucleus (c) and cytoplasm (e), respectively. Control DAPI stainings are shown (b, d, and f). Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172904&req=5

fig5: Intracellular localization of exogenous GFP-tagged PKP3 fragments in COS1 cells. Full-length PKP3 localizes at sites of cell–cell contact, and cytoplasmic aggregates are also observed (a). PKP3arm and head fragments localize predominantly in nucleus (c) and cytoplasm (e), respectively. Control DAPI stainings are shown (b, d, and f). Bar, 10 μm.
Mentions: Because COS cells were used in previous studies on PKP1 and PKP2 protein properties (Kowalczyk et al., 1999a; Chen et al., 2002), transfection experiments were repeated in this cell type. As shown in Fig. 5 , the intracellular localizations of full-length PKP3 (a and b), PKP3arm (c and d) and PKP3head (e and f) correspond with our observations made in MCF7/AZ, HCT8/E8 and PtK2 cells (unpublished observations in the latter cell type).

Bottom Line: We found that PKP3 binds all three desmogleins, desmocollin (Dsc) 3a and -3b, and possibly also Dsc1a and -2a.Evidence was found for the presence of at least two DP-PKP3 interaction sites.Together, these results show that PKP3, whose epithelial and epidermal desmosomal expression pattern and protein interaction repertoire are broader than those of PKP1 and -2, is a unique multiprotein binding element in the basic architecture of a vast majority of epithelial desmosomes.

View Article: PubMed Central - PubMed

Affiliation: Molecular Cell Biology Unit, Department for Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB)-Ghent University, B-9000 Ghent, Belgium.

ABSTRACT
Plakophilin 3 (PKP3) is a recently described armadillo protein of the desmosomal plaque, which is synthesized in simple and stratified epithelia. We investigated the localization pattern of endogenous and exogenous PKP3 and fragments thereof. The desmosomal binding properties of PKP3 were determined using yeast two-hybrid, coimmunoprecipitation and colocalization experiments. To this end, novel mouse anti-PKP3 mAbs were generated. We found that PKP3 binds all three desmogleins, desmocollin (Dsc) 3a and -3b, and possibly also Dsc1a and -2a. As such, this is the first protein interaction ever observed with a Dsc-b isoform. Moreover, we determined that PKP3 interacts with plakoglobin, desmoplakin (DP) and the epithelial keratin 18. Evidence was found for the presence of at least two DP-PKP3 interaction sites. This finding might explain how lateral DP-PKP interactions are established in the upper layers of stratified epithelia, increasing the size of the desmosome and the number of anchoring points available for keratins. Together, these results show that PKP3, whose epithelial and epidermal desmosomal expression pattern and protein interaction repertoire are broader than those of PKP1 and -2, is a unique multiprotein binding element in the basic architecture of a vast majority of epithelial desmosomes.

Show MeSH
Related in: MedlinePlus