Signaling pathways of ATP‐induced PGE2 release in spinal cord astrocytes are EGFR transactivation‐dependent

Abstract

Traumatic spinal cord injury is characterized by an immediate, irreversible loss of tissue at the lesion site, as well as a secondary expansion of tissue damage over time. Although secondary injury should, in principle, be preventable, no effective treatment options currently exist for patients with acute spinal cord injury (SCI). Excessive release of ATP by the traumatized tissue, triggers the rapid release of arachidonic acid (AA) and prostaglandin E2 (PGE2), and has beenimplicated in acute and chronic neuropathic pain and inflammation. But the intracellular pathways between ATP and PGE2 remain largely unknown. We have explored the signaling events involved in this synthesis by primarily culturing spinal cord astrocytes: (1) we determined significant PGE2 production increased by ATP is mainly via Subtype 1 of P2 purinoceptors (P2Y1) but not P2Y2; (2) we found that ATP strongly increased the level of intracellular Ca(2+) via P2Y1 receptor; (3) we indicated that ATP stimulates the definitely release of AA and PGE2 which involved the transactivation of epidermal growth factor (EGF) receptor, the phosphorylation of extracellular-regulated protein kinases 1 and 2 (ERK(1/2) ) and the activation of cytosolic phospholipase A(2) (cPLA(2) ); (4) we examined ATP could increase the phosphorylation of Akt via P2Y1 receptor which also depend on the transactivation of EGFR, but the activation of Akt has no effect on the downstream of cPLA(2) phosphorylation. ATP induced by SCI could mobilize the release of AA and PGE2. And inhibition of PGE2 release reduces behavioral signs of pain after SCI and peripheral nerve injury.

Selective Impairment of P2Y Signaling by Prostaglandin E2 in Macrophages: Implications for Ca2+-Dependent Responses

“…Macrophages from WT or P2X7-deficient mice (P2X7 KO) were prepared, and after the indicated time of culture in the presence or absence of LPS or IL-4/IL-13, cells were treated for 10 min with 5 mM PGE 2 , and the Ca 2+ responses to UTP (100 mM) or BzATP (300 mM) were determined using the dual excitation 340/380-nm protocol as described in nological approaches. In view of the confusion in the literature regarding the role of PGs on P2 signaling and macrophage activation (20,21,(59)(60)(61)(62)(63), we studied the role of these bioactive lipids on UTP-and ATP-dependent P2 responses. Preliminary experiments in macrophages carrying a COX-2 transgene revealed a rapid blockade of Ca 2+ mobilization induced by P2Y agonists that could be ascribed to the accumulation of PGE 2 in the culture medium.…”

Mechanisms of Mouse Neural Precursor Expansion after Neonatal Hypoxia-Ischemia

“…Unfortunately, the majority of the LIF-null mice could not withstand the H-I paradigm; therefore, they could not be analyzed. This outcome was not totally surprising as LIF has been reported to have a protective role in endotoxic shock and host defense (Weber et al, 2005), and LIF has been shown to reduce cutaneous inflammation (Zhu et al, 2001). By contrast, the LIF Hets had a similar SVZ cellular phenotype to the LIF nulls (Buono et al, 2012), and they survived the injury paradigm.…”

“…C57BL/6 neonates of either sex were used in the experiments presented in Figures 1, 2, 3, 4, 5, and 6, while LIF heterozygous (Hets) of either sex on a CD-1 background were used for Figure 7. The LIF mouse line was provided by Dr. Douglas Fields (National Institutes of Health, Bethesda, MD) with permission from Dr. Colin Stewart (Institute of Medical Biology, Singapore) (Stewart et al, 1992).…”

“…Further experiments will be needed to test this hypothesis. Additional data would enable us to better understand why there is replacement and maturation of oligodendrocytes after some injuries, whereas in other injuries there is a lack of differentiation with an accumulation of NG2 ϩ cells at the lesion (Levine, 1994;Chang et al, 2000;Watanabe et al, 2002).…”

“…The prevalence of neonatal H-I in the United States remains at 2-4 per 1000 full-term births despite major advancements in obstetric monitoring and perinatal care (Wyatt et al, 2007). Permanent neurological handicaps, including cerebral palsy and epilepsy, as well as cognitive, motor, and behavioral disorders develop in many infants who survive H-I (Nelson and Lynch, 2004).…”