Lab Anim Res.  2011 Mar;27(1):73-76.

Focal Cerebral Ischemia Reduces Protein Phosphatase 2A Subunit B Expression in Brain Tissue and HT22 Cells

• Koh PO

Abstract

Protein phosphatase 2A (PP2A) is a serine and threonine protein phosphatase that regulates cell cycle progression and apoptosis. PP2A is composed of various subunits. Among these subunits, subunit B plays an important role in the modulation of PP2A function in the brain. This study investigated PP2A subunit B expression levels after neuronal cell injury. Middle cerebral artery occlusions (MCAO) were surgically induced in adult male rats to induce focal cerebral ischemic injury, and brain tissues were collected 24 h after MCAO. A proteomic approach revealed reduction of PP2A subunit B protein spots in MCAO-operated animals in comparison to sham-operated animals. Western blot analysis confirmed that MCAO induces reductions in PP2A subunit B levels. Moreover, glutamate exposure induces neuronal cell death and leads to reductions of PP2A subunit B levels in a hippocampal-derived cell line. This study demonstrated the decrease of PP2A subunit B in ischemic neuronal cell injury. These results suggest that the decrease of PP2A subunit B after ischemic brain injury can mediate neuronal cell death.

Keyword

Glutamate; middle cerebral artery occlusion; PP2A subunit B

MeSH Terms

Adult
Animals
Apoptosis
Blotting, Western
Brain
Brain Injuries
Brain Ischemia
Cell Cycle
Cell Death
Cell Line
Glutamic Acid
Humans
Infarction, Middle Cerebral Artery
Male
Middle Cerebral Artery
Neurons
Protein Phosphatase 2
Rats
Serine
Threonine
Glutamic Acid
Protein Phosphatase 2
Serine
Threonine

Figure

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  Figure 1 Protein phosphatase 2A (PP2A) subunit B protein spots identified by MALDI-TOF. Arrows indicate the protein spots. The intensity of spots was measured using PDQuest software. The ratio of intensity is described as spots intensity of middle cerebral artery-occluded (MCAO) animal to spots intensity of sham-operated animal. Data are shown as mean±SEM. *P<0.05 (vs. Sham).

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  Figure 2 Western blot analysis of protein phosphatase 2A (PP2A) subunit B in the cerebral cortex from sham-operated and middle cerebral artery-occluded (MCAO) animals. Each lane represents an individual experimental animal. Densitometric analysis of PP2A levels is represented as intensity of PP2A to intensity of actin. Data are shown as mean±SEM. *P<0.05 (vs. Sham).

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  Figure 3 Western blot analysis of protein phosphatase 2A (PP2A) subunit B in HT22 cells. Glutamate (5 mM) or vehicle was exposed to HT22 cells for 24 h. Each lane represents an individual experimental animal. Densitometric analysis of PP2A levels is represented as intensity of PP2A to intensity of actin. Data are shown as mean±SEM. *P<0.05 (vs. Vehicle).

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