Defining desmosomal plakophilin-3 interactions.
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.
Bonné
Stefan
S
Molecular Cell Biology Unit, Department for Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB)-Ghent University, B-9000 Ghent, Belgium.
Gilbert
Barbara
B
Hatzfeld
Mechthild
M
Chen
Xinyu
X
Green
Kathleen J
KJ
van Roy
Frans
F
D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051187:Desmocollins; D051182:Desmogleins; D051180:Desmoplakins; D003896:Desmosomes / Q000378:metabolism* / Q000648:ultrastructure; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D051191:Plakophilins; D020033:Protein Isoforms / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D051185:gamma Catenin
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C081560:DSC1 protein, human; C495294:DSP protein, human; D051187:Desmocollins; D051182:Desmogleins; D051180:Desmoplakins; C489910:Dsc1 protein, mouse; C495295:Dsp protein, mouse; D008562:Membrane Glycoproteins; C495335:PKP1 protein, human; C495339:PKP3 protein, human; C495336:Pkp1 protein, mouse; C495340:Pkp3 protein, mouse; D051191:Plakophilins; D020033:Protein Isoforms; D051185:gamma Catenin; D007633:Keratins