Calreticulin and focal-contact-dependent adhesion.
Cell adhesion is regulated by a variety of Ca2+-regulated pathways that depend on Ca2+-binding proteins. One such protein is calreticulin, an ER-resident protein. Calreticulin signalling from within the ER can affect processes outside the ER, such as expression of several adhesion-related genes, most notably vinculin and fibronectin. In addition, changes in the expression level of calreticulin strongly affect tyrosine phosphorylation of cellular proteins, which is known to affect many adhesion-related functions. While calreticulin has been localized to cellular compartments other than the ER, it appears that only the ER-resident calreticulin affects focal-contact-dependent adhesion. In contrast, calreticulin residing outside the ER may be involved in contact disassembly and other adhesion phenomena. Here, we review the role of calreticulin in focal contact initiation, stabilization, and turnover. We propose that calreticulin may regulate cell-substratum adhesion by participating in an "ER-to-nucleus" signalling and in parallel "ER-to-cell surface" signalling based on posttranslational events.
Villagomez
Maria
M
Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Medical Sciences Building, Toronto, ON M5S 1A8, Canada.
Szabo
Eva
E
Podcheko
Alexey
A
Feng
Tianshu
T
Papp
Sylvia
S
Opas
Michal
M
D000818:Animals; D002118:Calcium / Q000502:physiology; D037282:Calreticulin / Q000378:metabolism / Q000502:physiology*; D002451:Cell Compartmentation; D022001:Focal Adhesions / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
D037282:Calreticulin; D014443:Tyrosine; D002118:Calcium