Differential stimulation of proline-rich tyrosine kinase 2 and mitogen-activated protein kinase by sphingosine 1-phosphate.
Sphingosine 1-phosphate (SphP), a metabolite of cellular sphingolipids, has been shown to induce cell proliferation by activating the mitogen-activated protein kinase (MAPK) pathway. Proline-rich tyrosine kinase 2 (Pyk2) is a novel cytosolic tyrosine kinase which mediates activation of the MAPK or c-Jun N-terminal kinase (JNK) signaling pathways in response to a variety of stimuli that elevate intracellular calcium. In this report, we show that SphP stimulates both tyrosine phosphorylation of Pyk2 and MAPK activation in a transient and dose-dependent manner in rat aortic smooth muscle cells. Further studies indicate that Pyk2 phosphorylation, but not MAPK activation, is dependent on a pertussis toxin-sensitive G-protein-coupled receptor as well as partially on actin cytoskeleton. In addition, both intracellular calcium mobilization and protein kinase C (PKC) are required for optimal Pyk2 phosphorylation while either calcium increase or PKC activation is sufficient for MAPK activation in response to SphP. Finally, we show that a tyrosine kinase(s) other than Pyk2 is necessary for MAPK activation by SphP. Together, these results suggest that SphP stimulates tyrosine phosphorylation of Pyk2 through a G-protein coupled receptor, which is dissociated from its activation of the MAPK pathway in these cells.
Guo
C
C
Department of Pathology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Zheng
C
C
Martin-Padura
I
I
Bian
Z C
ZC
Guan
J L
JL
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D051418:Focal Adhesion Kinase 2; D008246:Lysophospholipids; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism
D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496054:Ptk2b protein, rat; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013110:Sphingosine