A novel protein kinase C alpha-dependent signal to ERK1/2 activated by alphaVbeta3 integrin in osteoclasts and in Chinese hamster ovary (CHO) cells.

Abstract

We identified a novel protein kinase C (PKC)alpha-dependent signal to extracellular signal-regulated kinase (ERK)1/2 in mouse osteoclasts and Chinese hamster ovary (CHO) cells, specifically activated by the alphaVbeta3 integrin. It involves translocation (i.e. activation) of PKCalpha from the cytosol to the membrane and/or the Triton X-100-insoluble subcellular fractions, with recruitment into a complex with alphaVbeta3 integrin, growth factor receptor-bound protein (Grb2), focal adhesion kinase (FAK) in CHO cells and proline-rich tyrosine kinase (PYK2) in osteoclasts. Engagement of alphavbeta3 integrin triggered ERK1/2 phosphorylation, but the underlying molecular mechanism was surprisingly independent of the well known Shc/Ras/Raf-1 cascade, and of phosphorylated MAP/ERK kinase (MEK)1/2, so far the only recognized direct activator of ERK1/2. In contrast, PKCalpha was involved in ERK1/2 activation because inhibition of its activity prevented ERK1/2 phosphorylation. The tyrosine kinase c-Src also contributed to ERK1/2 activation, however, it did not interact with PKCalpha in the same molecular complex. The alphaVbeta3/PKCalpha complex formation was fully dependent upon the intracellular calcium concentration ([Ca2+]i), and the use of the intracellular Ca2+ chelator 1,2-bis(o-amino-phenoxy)ethane-N,N,N',N'-tetraaceticacidtetra (acetoxymethyl) ester (BAPTA-AM) also inhibited PKCalpha translocation and ERK1/2 phosphorylation. Functional studies showed that alphaVbeta3 integrin-activated PKCalpha was involved in cell migration and osteoclast bone resorption, but had no effect on the ability of cells to attach to LM609, suggesting a role in events downstream of alphaVbeta3 integrin engagement.

• Authors: Nadia Rucci, Claudia DiGiacinto, Luigi Orrù, Danilo Millimaggi, Roland Baron, Anna Teti
• Journal: Journal of cell science (J Cell Sci) Vol. 118 Issue Pt 15 Pg. 3263-75 (Aug 01 2005) ISSN: 0021-9533 [Print] England
• PMID: 16014375 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Carbazoles
• Indoles
• Integrin alphaVbeta3
• Go 6976
• Protein-Tyrosine Kinases
• CSK Tyrosine-Protein Kinase
• src-Family Kinases
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• Calcium

Topics

• Animals
• Antibodies, Monoclonal (pharmacology)
• Bone Resorption (metabolism)
• CHO Cells
• CSK Tyrosine-Protein Kinase
• Calcium (physiology)
• Carbazoles (pharmacology)
• Cell Movement (drug effects, physiology)
• Cricetinae
• Cricetulus
• Indoles (pharmacology)
• Integrin alphaVbeta3 (drug effects, physiology)
• Mice
• Mitogen-Activated Protein Kinase 1 (drug effects, metabolism)
• Mitogen-Activated Protein Kinase 3 (drug effects, metabolism)
• Osteoclasts (cytology, drug effects, metabolism)
• Phosphorylation
• Protein-Tyrosine Kinases (physiology)
• Signal Transduction (physiology)
• src-Family Kinases