Calreticulin affects focal contact-dependent but not close contact- dependent cell-substratum adhesion

Marc P. Fadel, Ewa Dziak, Chun Min Lo, Jack Ferrier, Nasrin Mesaeli, Marek Michalak, Michal Opas

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Abstract

We used two cell lines expressing fast (RPE(fast)) and slow (RPE(slow)) attachment kinetics to investigate mechanisms of cell-substratum adhesion. We show that the abundance of a cytoskeletal protein, vinculin, is dramatically decreased in RPE(fast) cells. This coincides with the diminished expression level of an endoplasmic reticulum chaperone, calreticulin. Both protein and mRNA levels for calreticulin and vinculin were decreased in RPE(fast) cells. After RPE(fast) cells were transfected with cDNA encoding calreticulin, both the expression of endoplasmic reticulum-resident calreticulin and cytoplasmic vinculin increased. The abundance of other adhesion-related proteins was not affected. RPE(fast) cells underexpressing calreticulin displayed a dramatic increase in the abundance of total cellular phosphotyrosine suggesting that the effects of calreticulin on cell adhesiveness may involve modulation of the activities of protein tyrosine kinases or phosphatases which may affect the stability of focal contacts. The calreticulin and vinculin underexpressing RPE(fast) cells lacked extensive focal contacts and adhered weakly but attached fast to the substratum. In contrast, the RPE(slow) cells that expressed calreticulin and vinculin abundantly developed numerous and prominent focal contacts slowly, but adhered strongly. Thus, while the calreticulin overexpressing RPE(slow) cells 'grip' the substratum with focal contacts, calreticulin underexpressing RPE(fast) cells use close contacts to 'stick' to it.

Original languageEnglish
Pages (from-to)15085-15094
Number of pages10
JournalJournal of Biological Chemistry
Volume274
Issue number21
DOIs
Publication statusPublished - 21 May 1999

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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