Faim2 contributes to neuroprotection by erythropoietin in transient brain ischemia

Abstract

Delayed cell death in the penumbra region of acute ischemic stroke occurs through apoptotic mechanisms, making it amenable to therapeutic interventions. Fas/CD95 mediates apoptotic cell death in response to external stimuli. In mature neurons, Fas/CD95 signaling is modulated by Fas-apoptotic inhibitory molecule 2 (Faim2), which reduces cell death in animal models of stroke, meningitis, and Parkinson disease. Erythropoietin (EPO) has been studied as a therapeutic strategy in ischemic stroke. Erythropoietin stimulates the phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway, which regulates Faim2 expression. Therefore, up-regulation of Faim2 may contribute to neuroprotection by EPO. Male Faim2-deficient mice (Faim2 ) and wild-type littermates (WT) were subjected to 30 min of middle cerebral artery occlusion (MCAo) followed by 72 h of reperfusion. EPO was applied before (30 min) and after (24 and 48 h) MCAo. In WT mice application of EPO at a low dose (5000 U/kg) significantly reduced stroke volume, whereas treatment with high dose (90 000 U/kg) did not. In Faim2 animals administration of low-dose EPO did not result in a significant reduction in stroke volume. Faim2 expression as measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) increased after low-dose EPO but not with high dose. An extensive phenotyping including analysis of cerebral vessel architecture did not reveal confounding differences between the genotypes. In human post-mortem brain Faim2 displayed a differential expression in areas of penumbral ischemia. Faim2 up-regulation may contribute to the neuroprotective effects of low-dose erythropoietin in transient brain ischemia. The dose-dependency may explain mixed effects of erythropoietin observed in clinical stroke trials.

EPO and TMBIM3/GRINA Promote the Activation of the Adaptive Arm and Counteract the Terminal Arm of the Unfolded Protein Response after Murine Transient Cerebral Ischemia

“…In addition, gene expression of TMBIM3/GRINA is dysregulated in brains of patients with major depression [34] and in various cancers [35]. GRINA-deficiency is not lethal in fruit flies [29] and does not show a pathological phenotype in mice, consistent with the knockout of other TMBIM family members (FAIM2, TMBIM1 and TMBIM6) [30,33,36,37]. Mostly located at the ER membrane and inhibiting ER calcium release by inositol-1,4,5-trisphosphate receptors, GRINA might have a crucial role in diminishing ER stress.…”

Prolonged astrocyte-derived erythropoietin expression attenuates neuronal damage under hypothermic conditions

“…We reported previously that EPO secreted by astrocytes is protective for several brain cell types [21][22][23]. In addition, studies involving animal models have shown that EPO in the brain contributes significantly to neuroprotection [24][25][26][27]. Based on these data, we examined the effect of hypothermia on EPO expression in cultured astrocytes.…”

Protective effects of ischemic preconditioning against neuronal apoptosis and dendritic injury in the hippocampus are age‐dependent

“…After the calculation with (5 timepoints × 6 gerbils/timepoint) – (5 timepoints)= 25, the number of 25 suggested the sample size in this experiment could be more than necessary, and six gerbils were used for each timepoint (Charan & Kantharia, 2013). Alternatively, we used G*Power with the select procedure using effect size from means (Komnig, Dagli, et al., 2018; Komnig, Gertz, et al., 2018) for further confirmation, which produced similar results. We firstly searched the papers dealing with ischemic preconditioning in the literature to calculate the sample size (A in Table S1).…”

“…However, we excluded gerbils with no significant ischemic injury of apoptosis and surviving cells in the CA1 area according to the ischemic period including 2 adult gerbils (1 in sham + 15‐min and 1 in 5 + 15‐min ischemia) and five middle‐aged gerbils (4 in sham + 15‐min and 1 in 5 + 15‐min ischemia) (Figure 1, C + D). Different from the previous studies (Komnig, Dagli, et al., 2018; Komnig, Gertz, et al., 2018) that included those animals died and had their samples lost or not well treated during experiments within the target of sample size, this study did not include any animals that died or had their samples lost or not well treated during experiments in our sample size calculation (Figure 1, C + D). The final number of six gerbils was reached for analysis at each time point in the four experimental groups with a final number of 72 in each adult and middle‐aged gerbil group.…”

“…The experimental procedures in “ischemic preconditioning and transient forebrain ischemia,” “the magnetic resonance imaging, histopathology, and immunostaining,” and “the statistical analysis” were performed by three different technical assistants who were not involved in the simple random assignment without stratification of animals to the experimental groups (Figure 1c). Numerical sample identifiers were used during sample preparation and analysis, and the investigators were blind to the treatment (Komnig, Dagli, et al., 2018; Komnig, Gertz, et al., 2018).…”