Role of the calpain-calpastatin system in the density-dependent growth arrest.
In dividing cells calpastatin diffuses from aggregates into cytosol, indicating the requirement for a tight regulation of calpain. Accordingly, the involvement of the calpain-calpastatin system in cell proliferation and in the density-dependent growth arrest was studied in JA3 cells stably transfected with a calpastatin form permanently localized in cytosol. In calpastatin overexpressing cells, cell cycle rate is 50% reduced, and cells enter the ungrowing, still fully reversible, stage at a 3-fold higher cell density. Furthermore, in cell density growth arrest phase, down regulation of alpha- and theta-PKC isoforms, as well as FAK and talin occurs. In calpastatin overexpressing cells, degradation of these calpain substrate proteins is prevented and delayed. Thus, calpain activity plays a crucial role in inducing the cell entry into a functional quiescent phase.
Stifanese
Roberto
R
Department of Experimental Medicine (DIMES), Section of Biochemistry, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy.
Averna
Monica
M
De Tullio
Roberta
R
Salamino
Franca
F
Cantoni
Claudia
C
Mingari
Maria Cristina
MC
Prato
Carola
C
Pontremoli
Sandro
S
Melloni
Edon
E
D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002154:Calpain / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D003600:Cytosol / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D019169:Jurkat Cells; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism; D000074121:Protein Kinase C-theta; D051381:Rats
D002135:Calcium-Binding Proteins; D007527:Isoenzymes; C033668:calpastatin; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C496052:Ptk2 protein, rat; C076233:PRKCQ protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D000074121:Protein Kinase C-theta; D002154:Calpain