Pro-life role for c-Jun N-terminal kinase and p38 mitogen-activated protein kinase at rostral ventrolateral medulla in experimental brain stem death

Abstract

BackgroundBased on an experimental brain stem death model, we demonstrated previously that activation of the mitogen-activated protein kinase kinase 1/2 (MEK1/2)/extracellular signal-regulated kinase 1/2 (ERK1/2)/ mitogen-activated protein kinase signal-interacting kinase 1/2 (MNK1/2) cascade plays a pro-life role in the rostral ventrolateral medulla (RVLM), the origin of a life-and-death signal detected from systemic arterial pressure, which sequentially increases (pro-life) and decreases (pro-death) to reflect progressive dysfunction of central cardiovascular regulation during the advancement towards brain stem death in critically ill patients. The present study assessed the hypothesis that, in addition to ERK1/2, c-Jun NH2-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK), the other two mammalian members of MAPKs that are originally identified as stress-activated protein kinases, are activated specifically by MAPK kinase 4 (MAP2K4) or MAP2K6 and play a pro-life role in RVLM during experimental brain stem death. We further delineated the participation of phosphorylating activating transcriptional factor-2 (ATF-2) and c-Jun, the classical transcription factor activated by JNK or p38MAPK, in this process.ResultsAn experimental model of brain stem death that employed microinjection of the organophosphate insecticide mevinphos (Mev; 10 nmol) bilaterally into RVLM of Sprague–Dawley rats was used, alongside cardiovascular, pharmacological and biochemical evaluations. Results from ELISA showed that whereas the total JNK, p38MAPK, MAP2K4 and MAP2K6 were not affected, augmented phosphorylation of JNK at Thr183 and Tyr185 and p38MAPK at Thr180 and Tyr182, accompanied by phosphorylation of their upstream activators MAP2K4 at Ser257 and Thr261 and MAP2K6 at Ser207 and Thr211 in RVLM occurred preferentially during the pro-life phase of experimental brain stem death. Moreover, the activity of transcription factors ATF-2 at Thr71 and c-Jun at Ser73, rather than Elk-1 at Ser383 in RVLM were also augmented during the pro-life phase. Furthermore, pretreatment by microinjection into the bilateral RVLM of specific JNK inhibitors, JNK inhibitor I (100 pmol) or SP600125 (5 pmol), or specific p38MAPK inhibitors, p38MAPK inhibitor III (500 pmol) or SB203580 (2 nmol), exacerbated the depressor effect and blunted the augmented life-and-death signal exhibited during the pro-life phase. On the other hand, pretreatment with the negative control for JNK or p38MAPK inhibitor, JNK inhibitor I negative control (100 pmol) or SB202474 (2 nmol), was ineffective in the vehicle-controls and Mev-treatment groups.ConclusionsOur results demonstrated that activation of JNK or p38MAPK in RVLM by their upstream activators MAP2K4 or MAP2K6 plays a preferential pro-life role by sustaining the central cardiovascular regulatory machinery during experimental brain stem death via phosphorylation and activation of nuclear transcription factor ATF-2 or c-Jun.

C-Jun NH2-Terminal Kinase and p38 Inhibition Suppresses Prostaglandin E2-Stimulated Aromatase and Estrogen Receptor Levels in Human Endometriosis

“…MAPKs pathways are activated in response to a variety of extracellular and intracellular stimuli (15)(16)(17). Stimulation of MAPKs requires dual phosphorylation, which occurs as a consequence of sequential activation (18).…”

Neuroprotective effect of berberine against learning and memory deficits in diffuse axonal injury

“…Macrophages at an ischemic core region may present activated p38 MAPK, indicating that p38 MAPK may participate in the inflammatory responses when cerebral ischemic injury occurs (26). Activated p38 MAPK can enter into the cell nucleus or shift to other regions (27), and may further activate various transcription factors, including ATF-2/6, ATH-1/2, ETS21, MAX, HSF21, myocyte enhancer binding factor-22, nuclear transcription factor 2P, CHOP/GADD153, Elk-1 and SAP-1 (28). A study by Liu et al indicated that berberine reduces fibronectin and collagen accumulation through the p38 MAPK signaling pathway in rat glomerular mesangial cells (29).…”

Activation of p38-mitogen-activated protein kinase contributes to ischemia reperfusion in rat brain

“…ET-1 induction can also lead to upregulation of the COX-2/ PGE2 system in brain microvascular endothelial cells by activation of ETB-dependent MAPK cascades (Lin et al, 2013;Chuang et al, 2014). Based on a clinically relevant experimental model, it has been demonstrated that activation of both JNK and p38mapk in the rostral ventrolateral medulla sustains central cardiovascular regulation during progression towards brain stem death (Chang, 2012).…”