Temporal Differences in MicroRNA Expression Patterns in Astrocytes and Neurons after Ischemic Injury

Abstract

MicroRNAs (miRNAs) are small, non-protein-coding RNA molecules that modulate gene translation. Their expression is altered in many central nervous system (CNS) injuries suggesting a role in the cellular response to stress. Current studies in brain tissue have not yet described the cell-specific temporal miRNA expression patterns following ischemic injury. In this study, we analyzed the expression alterations of a set of miRNAs in neurons and astrocytes subjected to 60 minutes of ischemia and collected at different time-points following this injury. To mimic ischemic conditions and reperfusion in vitro, cortical primary neuronal and astrocytic cultures prepared from fetal rats were first placed in oxygen and glucose deprived (OGD) medium for 60 minutes, followed by their transfer into normoxic pre-conditioned medium. Total RNA was extracted at different time-points after the termination of the ischemic insult and the expression levels of miRNAs were measured. In neurons exposed to OGD, expression of miR-29b was upregulated 2-fold within 6 h and up to 4-fold at 24 h post-OGD, whereas induction of miR-21 was upregulated 2-fold after 24 h when compared to expression in neurons under normoxic conditions. In contrast, in astrocytes, miR-29b and miR-21 were upregulated only after 12 h. MiR-30b, 107, and 137 showed expression alteration in astrocytes, but not in neurons. Furthermore, we show that expression of miR-29b was significantly decreased in neurons exposed to Insulin-Like Growth Factor I (IGF-I), a well documented neuroprotectant in ischemic models. Our study indicates that miRNAs expression is altered in neurons and astrocytes after ischemic injury. Furthermore, we found that following OGD, specific miRNAs have unique cell-specific temporal expression patterns in CNS. Therefore the specific role of each miRNA in different intracellular processes in ischemic brain and the relevance of their temporal and spatial expression patterns warrant further investigation that may lead to novel strategies for therapeutic interventions.

Revealing the Underlying Mechanism of Ischemia Reperfusion Injury Using Bioinformatics Approach

“…Ouyang, Y.B., et al have reported that astrocyte-enriched miR-29a targets PUMA and reduces neuronal vulnerability to forebrain ischemia [29]. Additionally, Mateo Ziu et al have found that expression of miR-29b is significantly decreased in neurons exposed to insulin-like growth factor 1, a well documented neuroprotectant in ischemic models [30]. Our results are consistent with these previous findings.…”

Protective effect of mild hypothermia on oxygen-glucose deprivation injury in rat hippocampal neurons after hypoxia

“…Therefore, it is often used to investigate changes in biochemistry and cell morphology induced by ischemia and hypoxia and the relevant molecular biology mechanisms (23). Simulating ischemia and hypoxia among in vivo neurons using the OGD model is currently an important research topic and the model is widely used to investigate ischemic and hypoxic encephalopathy (24)(25)(26)(27).…”

miR-711 upregulation induces neuronal cell death after traumatic brain injury

“…1 Although miRs have been implicated in the pathophysiology of central nervous system (CNS) disorders [2][3][4] and may modulate neuronal cell death pathways, 5 few have been directly evaluated at a mechanistic level in traumatic brain injury (TBI). 6,7 TBI initiates regulated neuronal death mechanisms that significantly contribute to neuronal loss and neurological dysfunction.…”