Intercellular adhering junctions with an asymmetric molecular composition: desmosomes connecting Merkel cells and keratinocytes.

TY - JOUR

T1 - Intercellular adhering junctions with an asymmetric molecular composition: desmosomes connecting Merkel cells and keratinocytes.

AU - Rickelt, Steffen

AU - Moll, Ingrid

AU - Franke, Werner Wilhelm

PY - 2011

Y1 - 2011

N2 - Merkel cells (MCs) are special neuroendocrine epithelial cells that occur as individual cells or as cell groups within the confinements of a major epithelium formed and dominated by other epithelial cells. In the epidermis and some of its appendages MCs are mostly located in the basal cell layer, occasionally also in suprabasal layers and generally occur in linear arrays in outer root sheath cell layers of hair follicles. As MCs are connected to the adjacent keratinocytes by a series of adhering junctions (AJs), of which the desmosomes are the most prominent, these junctions represent heterotypic cell-cell connections, i.e. a kind of structure not yet elucidated in molecular terms. Therefore, we have studied these AJs in order to examine the molecular composition of the desmosomal halves. Using light- and electron-microscopic immunolocalization and keratin 20 as the MC-specific cell type marker we show that the plaques of the MC half of the desmosomes specifically and constitutively contain plakophilin Pkp2. This protein, however, is absent in the keratinocyte half of such heterotypic desmosomes which instead contains Pkp1 and/or Pkp3. We discuss the developmental, tissue-architectonic and functional importance of such asymmetric junctions in normal physiology as well as in diseases, in particular in the formation of distant tumor cell metastasis.

AB - Merkel cells (MCs) are special neuroendocrine epithelial cells that occur as individual cells or as cell groups within the confinements of a major epithelium formed and dominated by other epithelial cells. In the epidermis and some of its appendages MCs are mostly located in the basal cell layer, occasionally also in suprabasal layers and generally occur in linear arrays in outer root sheath cell layers of hair follicles. As MCs are connected to the adjacent keratinocytes by a series of adhering junctions (AJs), of which the desmosomes are the most prominent, these junctions represent heterotypic cell-cell connections, i.e. a kind of structure not yet elucidated in molecular terms. Therefore, we have studied these AJs in order to examine the molecular composition of the desmosomal halves. Using light- and electron-microscopic immunolocalization and keratin 20 as the MC-specific cell type marker we show that the plaques of the MC half of the desmosomes specifically and constitutively contain plakophilin Pkp2. This protein, however, is absent in the keratinocyte half of such heterotypic desmosomes which instead contains Pkp1 and/or Pkp3. We discuss the developmental, tissue-architectonic and functional importance of such asymmetric junctions in normal physiology as well as in diseases, in particular in the formation of distant tumor cell metastasis.

KW - Animals

KW - Humans

KW - Female

KW - Mice

KW - Rats

KW - Cattle

KW - Swine

KW - Adherens Junctions/metabolism/ultrastructure

KW - Desmosomes/metabolism/ultrastructure

KW - Keratinocytes/metabolism/ultrastructure

KW - Merkel Cells/metabolism/ultrastructure

KW - Plakophilins/metabolism

KW - Animals

KW - Humans

KW - Female

KW - Mice

KW - Rats

KW - Cattle

KW - Swine

KW - Adherens Junctions/metabolism/ultrastructure

KW - Desmosomes/metabolism/ultrastructure

KW - Keratinocytes/metabolism/ultrastructure

KW - Merkel Cells/metabolism/ultrastructure

KW - Plakophilins/metabolism

M3 - SCORING: Journal article

VL - 346

SP - 65

EP - 77

JO - CELL TISSUE RES

JF - CELL TISSUE RES

SN - 0302-766X

IS - 1

M1 - 1

ER -