Cytochrome oxidase activity during acute focal ischaemia in rat brain. A pathophysiology of acute focal ischaemia: Part 2

Screening of AMP-activated protein kinase alpha2 subunit interacting proteins by bacterial two-hybrid system

AMP-activated protein kinase (AMPK) is a ubiquitous eukaryotic protein kinase regulating cellular metabolism and energy demand. In brain AMPK plays a role as a multidimensional energy sensor and AMPK alpha2 subunit is expressed at higher levels than AMPK alpha1 subunit. In order to identify potential targets of AMPK in brain, we perform bacterial two-hybrid screening of a rat fetal brain cDNA library using AMPK alpha2 subunit as bait. Here, we present seven potential AMPK alpha2 subunit interacting proteins, including 6-phosphofructo-1-kinase (PFK-1), polyubiquitin, cytochrome c oxidase subunit I (COX I), heat shock protein 8 (HSP8), HLA-B-associated transcript 3 (BAT3) isoform 1, protein tyrosine phosphatase receptor type D (PTPRD) and islet-brain 1 (IB1). They are involved in glycolysis, protein degradation, mitochondrial electron transport and apoptosis pathways participating in energy regulation directly or indirectly. These data may provide new insight into further studying the pathways of AMPK energy regulation in brain and possible mechanisms of AMPK-mediated neuroprotective effect.

Involvement of multitargets in paeoniflorin-induced preconditioning

Paeoniflorin (PF) is the principal component of Paeoniae radix prescribed in traditional Chinese medicine. The delayed neuroprotection induced by PF preconditioning and its underlying mechanisms were investigated in rat middle cerebral artery occlusion (MCAO) and reperfusion model. At a dosage of 20 or 40 mg/kg, PF preconditioning 48 h before MCAO followed by 24-h reperfusion significantly reduced the mortality and infarct volume and reversed the neurological deficits caused by ischemia. Likewise, the ameliorative effects on mortality, infarct size, and neurological impairment induced by MCAO emerged as well when PF was administered 24 h, 48 h, or 5 days before MCAO at the dose of 20 mg/kg. Furthermore, comparative proteomics analysis was adopted to identify the differentially expressed proteins induced by PF preconditioning itself. The relative levels of 42 proteins were altered after PF preconditioning, among which 20 were elevated and 22 reduced. In summary, A(1) receptor-regulator of G protein signaling-K(ATP) signaling, arachidonic acid cascade, nitric oxide system, markers of neuronal damage, mitochondrial damage-related molecules, and the mitogen-activated protein kinase and nuclear factor-kappaB pathway are associated with the mechanisms of PF preconditioning.