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Activation of mitogen-activated protein kinases after permanent cerebral artery occlusion in mouse brain
Abstract:
The purpose of this study was to examine the activation, topographic distribution, and cellular location of three mitogen-activated protein kinases (MAPKs) after permanent middle cerebral artery occlusion (MCAO) in mice. Phosphorylated MAPKs expression in the ischemic region was quantified using Western blot analysis and localized immunohistochemically using the diaminobenzide staining and double-labeled immunostaining. Extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2), p38 mitogen-activated protein (p38), and c-Jun NH2-terminal kinase or stress-activated protein kinase (SAPK/JNK) were initially activated at 30 minutes, 10 minutes, and 5 minutes, respectively, after focal cerebral ischemia. Peak expression represented a 2.7-fold, 3.7-fold, and 4.8-fold increase in each of these MAPKs, respectively. The immunohistochemical expressions of ERK1, ERK2, p38, and SAPK/JNK protein paralleled the Western blot analysis results. Double-labeled immunofluorescent staining demonstrated that the neurons and astrocytes expressed ERK1, ERK2, p38, and SAPK/JNK during the early time points after MCAO. The current results demonstrate that brain damage after ischemia rapidly triggers time-dependent ERK1, ERK2, p38, and SAPK/ JNK phosphorylation, and reveals that neurons and astrocytes are involved in the activation of the MAPK pathway. This very early expression of MAPKs suggests that MAPKs may be closely involved in signal transduction during cerebral ischemia.
Insights
Brain damage from stroke rapidly activates mitogen-activated protein kinases (MAPKs) in neurons and astrocytes. This early MAPK pathway signaling suggests a key role in cerebral ischemia.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Mitogen-activated protein kinases (MAPKs) are crucial signaling molecules involved in cellular responses to various stimuli.
- Understanding MAPK activation in the context of ischemic stroke is vital for developing targeted therapeutic strategies.
Purpose of the Study:
- To investigate the activation, distribution, and cellular localization of three key MAPKs (ERK1/2, p38, SAPK/JNK) following ischemic stroke.
- To elucidate the temporal dynamics of MAPK expression in the ischemic brain region.
Main Methods:
- Permanent middle cerebral artery occlusion (MCAO) model in mice to induce focal cerebral ischemia.
- Western blot analysis to quantify phosphorylated MAPK expression.
- Immunohistochemistry and double-labeled immunofluorescence to determine cellular localization.
Main Results:
- MAPKs (ERK1/2, p38, SAPK/JNK) showed rapid activation within minutes after MCAO, with peak expression at 5-30 minutes.
- Expression levels increased significantly (2.7 to 4.8-fold) for each MAPK.
- Neurons and astrocytes were identified as the primary cell types expressing these activated MAPKs in the early stages post-ischemia.
Conclusions:
- Ischemic brain injury triggers rapid, time-dependent phosphorylation of ERK1/2, p38, and SAPK/JNK.
- Neurons and astrocytes are key players in the early MAPK pathway activation following cerebral ischemia.
- The prompt MAPK expression suggests their significant involvement in early signal transduction processes during ischemic stroke.