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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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Immunohistochemical detection of PKP3 in paraffin sections of formalin-fixed human skin and colon using mAb 23E3/4. PKP3 is expressed in the living cell layers of the epidermis, but not in the stratum corneum and the dermis (a). At higher magnification, the interrupted PKP3 localization along cell–cell contacts is visible (b). The epidermal cells of the hair root also express PKP3 (c); no signal can be detected in the negative control sections, in which the primary antibody was omitted (d). PKP3 is expressed in simple colon epithelium (e); no signal is observed in the negative control sections (f). SC, stratum corneum; E, epidermis; D, dermis. Bars: 20 μm (a and c–e), 10 μm (b), and 100 μm (f).
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fig2: Immunohistochemical detection of PKP3 in paraffin sections of formalin-fixed human skin and colon using mAb 23E3/4. PKP3 is expressed in the living cell layers of the epidermis, but not in the stratum corneum and the dermis (a). At higher magnification, the interrupted PKP3 localization along cell–cell contacts is visible (b). The epidermal cells of the hair root also express PKP3 (c); no signal can be detected in the negative control sections, in which the primary antibody was omitted (d). PKP3 is expressed in simple colon epithelium (e); no signal is observed in the negative control sections (f). SC, stratum corneum; E, epidermis; D, dermis. Bars: 20 μm (a and c–e), 10 μm (b), and 100 μm (f).

Mentions: mAb 23E3/4 was also used on paraffin sections of formalin-fixed human skin and colon. PKP3 is detected in all living layers of the human epidermis, but not in the stratum corneum or dermis (Fig. 2 a). At higher magnifications, the punctate localization of PKP3 along cell–cell contacts, typical of desmosomal components, is clearly visible (Fig. 2 b). Epidermal cells of the hair follicle also synthesize PKP3 (Fig. 2 c), and PKP3 protein was observed in both the inner and outer root sheats of hair follicles (unpublished data). No signal could be detected in the negative control sections, in which the primary antibody was omitted (Fig. 2 d). PKP3 was also detected in vivo in simple epithelia such as colon (Fig. 2 e), whereas no signal was observed in the corresponding negative control sections (Fig. 2 f). In line with previously reported expression data on PKP3 (Bonné et al., 1999; Schmidt et al., 1999), the present results show that PKP3 is cosynthesized with the differentiation- and cell type–specific desmosomal cadherins, and with both PKP1 and PKP2, in single- and multilayered epithelia.


Defining desmosomal plakophilin-3 interactions.

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

Immunohistochemical detection of PKP3 in paraffin sections of formalin-fixed human skin and colon using mAb 23E3/4. PKP3 is expressed in the living cell layers of the epidermis, but not in the stratum corneum and the dermis (a). At higher magnification, the interrupted PKP3 localization along cell–cell contacts is visible (b). The epidermal cells of the hair root also express PKP3 (c); no signal can be detected in the negative control sections, in which the primary antibody was omitted (d). PKP3 is expressed in simple colon epithelium (e); no signal is observed in the negative control sections (f). SC, stratum corneum; E, epidermis; D, dermis. Bars: 20 μm (a and c–e), 10 μm (b), and 100 μm (f).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172904&req=5

fig2: Immunohistochemical detection of PKP3 in paraffin sections of formalin-fixed human skin and colon using mAb 23E3/4. PKP3 is expressed in the living cell layers of the epidermis, but not in the stratum corneum and the dermis (a). At higher magnification, the interrupted PKP3 localization along cell–cell contacts is visible (b). The epidermal cells of the hair root also express PKP3 (c); no signal can be detected in the negative control sections, in which the primary antibody was omitted (d). PKP3 is expressed in simple colon epithelium (e); no signal is observed in the negative control sections (f). SC, stratum corneum; E, epidermis; D, dermis. Bars: 20 μm (a and c–e), 10 μm (b), and 100 μm (f).
Mentions: mAb 23E3/4 was also used on paraffin sections of formalin-fixed human skin and colon. PKP3 is detected in all living layers of the human epidermis, but not in the stratum corneum or dermis (Fig. 2 a). At higher magnifications, the punctate localization of PKP3 along cell–cell contacts, typical of desmosomal components, is clearly visible (Fig. 2 b). Epidermal cells of the hair follicle also synthesize PKP3 (Fig. 2 c), and PKP3 protein was observed in both the inner and outer root sheats of hair follicles (unpublished data). No signal could be detected in the negative control sections, in which the primary antibody was omitted (Fig. 2 d). PKP3 was also detected in vivo in simple epithelia such as colon (Fig. 2 e), whereas no signal was observed in the corresponding negative control sections (Fig. 2 f). In line with previously reported expression data on PKP3 (Bonné et al., 1999; Schmidt et al., 1999), the present results show that PKP3 is cosynthesized with the differentiation- and cell type–specific desmosomal cadherins, and with both PKP1 and PKP2, in single- and multilayered epithelia.

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