Sphingosylphosphorylcholine stimulates mitogen-activated protein kinase via a Ca²⁺-dependent pathway

Abstract

In cultured porcine aortic smooth muscle cells, sphingosylphosphorylcholine (SPC), ATP, or bradykinin (BK) induced a rapid dose-dependent increase in the cytosolic Ca2+ concentration ([Ca2+]i) and also stimulated inositol 1,4,5-trisphosphate (IP3) generation. Pretreatment of cells with pertussis toxin blocked the SPC-induced IP3 generation and [Ca2+]iincrease but had no effect on the action of ATP or BK. In addition, SPC stimulated the mitogen-activated protein kinase (MAPK) and increased DNA synthesis, whereas neither ATP nor BK produced such effects. Both the SPC-induced MAPK activation and DNA synthesis were pertussis toxin sensitive. SPC-induced MAPK activation was blocked by treatment of cells with the phospholipase C inhibitor, U-73122, or the intracellular Ca2+-ATPase inhibitor, thapsigargin, but not by removal of extracellular Ca2+. Lysophosphatidic acid induced cellular responses similar to SPC in a pertussis toxin-sensitive manner in terms of [Ca2+]iincrease, IP3 generation, MAPK activation, and DNA synthesis. Platelet-derived growth factor (PDGF) also induced a [Ca2+]iincrease, MAPK activation, and DNA synthesis in the same cells; however, the PDGF-induced MAPK activation was not sensitive to pertussis toxin and changes in [Ca2+]i. SPC-induced MAPK activation was inhibited by pretreatment of cells with staurosporine, W-7, or calmidazolium. Our results suggest that, in porcine aortic smooth muscle cells, MAPK is not activated by the increase in [Ca2+]iunless a pertussis toxin-sensitive G protein is simultaneously stimulated, indicating the role of Ca2+ in pertussis toxin-sensitive G protein-mediated MAPK activation.

Novel synthetic ceramide derivatives increase intracellular calcium levels and promote epidermal keratinocyte differentiation

“…For example, SPC-induced p42/44 ERK activation is critically dependent on increases in intracellular calcium in porcine aortic smooth muscle cells (28). Consistent with this, our novel synthetic ceramide derivatives increased the intracellular calcium rapidly, and the phosphorylation of p42/44 ERK and JNK was observed slightly later in keratinocytes cultured in vitro.…”

Sphingosylphosphorylcholine induces differentiation of human mesenchymal stem cells into smooth-muscle-like cells through a TGF-β-dependent mechanism

“…In vasculature, SPC has been reported to induce migration and morphogenesis of endothelial cells and contraction of SMCs (Boguslawski et al, 2000;Kim et al, 2005), suggesting that SPC may play a role in the maintenance of vascular structure, biochemical stability and functionality of vessels. The SPC-induced cellular responses are sensitive to pertussis toxin (PTX), indicating an involvement of G i/o -coupled receptors (Xu, 2002;Chin and Chueh, 1998;Seufferlein and Rozengurt, 1995). In a previous study, we demonstrated that SPC stereo-specifically stimulates or inhibits the proliferation of human adipose-tissue-derived mesenchymal stem cells (hATSCs), depending on the concentration of SPC used (Jeon et al, 2005;Jeon et al, 2006).…”

Sphingosylphosphorylcholine induces proliferation of human adipose tissue-derived mesenchymal stem cells via activation of JNK

“…In particular, SPC takes part in several cellular responses, such as migration, wound healing, and differentiation (9,(11)(12)(13), and is known to stimulate DNA synthesis and proliferation in various cell types, including fibroblasts, endothelial cells, keratinocytes, and vascular smooth muscle cells, as a potent mitogen (9,12,(14)(15)(16). In contrast to the above, SPC can also inhibit the growth of various cell types, mostly that of tumor cells such as pancreatic, breast, and ovarian cancer cells and Jurkat T-cells (13,17).…”