A novel type of adhering junction in an epithelioid tumorigenic rat cell culture line

Monika Schmelz, Dennis L. Way, Peter Borgs, Wiebke K. Peitsch, Hannelore Schmidt, Marlys H. Witte, Charles L. Witte, Werner W. Franke, Roland Moll

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Two major types of plaque-bearing adhering junctions are commonly distinguished: the actin microfilament-anchoring adhaerens junctions (AJs) and the desmosomes anchoring intermediate-sized filaments (IFs). Both types of junction usually possess the common plaque protein, plakoglobin, whereas the other plaque proteins and the transmembrane cadherins are mutually exclusive. For example, AJs contain E-, N-, or P-cadherin in combination with α- and β-catenin, vinculin and α-actinin, whereas in desmosomes, desmogleins and desmocollins are associated with desmoplakin and one or several of the plakophilins (PP1-3). Here we describe a novel type of adhering junction comprising proteins of both AJs and desmosomes and the tight junction (TJ) plaque protein, ZO-1, in a newly established, liver-derived tumorigenic rat cell line (RMEC-1). By immunofluorescence microscopy, cell-cell contacts are characterized by mostly continuous-appearing lines which are usually resolved by electron microscopy as extended arrays of closely spaced small plaque subunits. These plaque-covered regions are positive for plakoglobin, α- and β-catenin, the arm-repeat protein p120, vinculin, desmoplakin and protein ZO-1. They are positive for E-cadherin in cultures early on in passaging, but tend to turn negative for all known cadherins in densely grown cultures. On immunoblotting SDS-PAGE-separated proteins from dense-grown cell monolayers, 'pan-cadherin' antibodies have reacted with a band at ~ 140 kDa, identified as N-cadherin by peptide fingerprinting of the immunoprecipitated protein, which for reasons not yet clear is modified or masked in immunolocalization experiments. The exact histological derivation of RMEC-1 cells is not known. However, the observations of several endothelial markers and the fact that all cells are rich in IFs containing vimentin and/or desmin, while only subpopulations also reveal IFs containing CKs 8 and 18, is suggestive of a mesenchymal, probably endothelial origin. We discuss the molecular relationship of this novel type of extended junction with other types of adhering junctions.

Original languageEnglish (US)
Pages (from-to)11-25
Number of pages15
JournalCell and Tissue Research
Issue number1
StatePublished - 1998


  • Adhering junctions
  • Cadherins
  • Desmoplakin
  • Desmosomes
  • Endothelial junctions
  • Plaque proteins
  • Protein ZO-1
  • Rat, cell culture

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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