Limits...
Temporal differences in microRNA expression patterns in astrocytes and neurons after ischemic injury.

Ziu M, Fletcher L, Rana S, Jimenez DF, Digicaylioglu M - PLoS ONE (2011)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America.

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.

Show MeSH

Related in: MedlinePlus

Effects of oxygen-glucose deprivation on miRNA expression in neurons and astrocytes.RNA was isolated from purified cortical neurons or astrocytes that had undergone OGD (1 h) or were maintained in normoxic conditions. RNA concentrations were determined by UV absorbance, and 10 ng for each sample was converted into cDNA and expression levels were measured using RT-PCR[55]. The fold-change in expression of each miRNA compared to that of the normoxic specimen was calculated using 2−ΔC’T formula. Data is expressed as the mean ± the SE (n = 4). The results were analyzed by one-way ANOVA followed by multiple comparisons test (* p<0.05, normoxia versus OGD within each cell type). Differences in the mean expression level for each miRNA between the two different cell types was compared for each time point post-OGD by Student's t test (# p<0.05, astrocyte versus neuron).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3044134&req=5

pone-0014724-g001: Effects of oxygen-glucose deprivation on miRNA expression in neurons and astrocytes.RNA was isolated from purified cortical neurons or astrocytes that had undergone OGD (1 h) or were maintained in normoxic conditions. RNA concentrations were determined by UV absorbance, and 10 ng for each sample was converted into cDNA and expression levels were measured using RT-PCR[55]. The fold-change in expression of each miRNA compared to that of the normoxic specimen was calculated using 2−ΔC’T formula. Data is expressed as the mean ± the SE (n = 4). The results were analyzed by one-way ANOVA followed by multiple comparisons test (* p<0.05, normoxia versus OGD within each cell type). Differences in the mean expression level for each miRNA between the two different cell types was compared for each time point post-OGD by Student's t test (# p<0.05, astrocyte versus neuron).

Mentions: MiR-21 was upregulated 1.5-fold at 12 h and 1.94-fold (p<0.05) at 24 h post-OGD as compared to expression in control neurons. MiR-29b showed the highest expression alteration in neurons exposed to OGD. It was upregulated by 1.6-fold at 2 h post-OGD (p<0.05), and 4-fold (p<0.05) at 24 h suggesting a strong involvement of this miRNA in the neuronal response to ischemia. MiR-30b, miR-107 and miR-137 did not alter their expression levels in neurons. MiR-210 was more than 2-fold upregulated at 12 h and 24 h (Figure 1).


Temporal differences in microRNA expression patterns in astrocytes and neurons after ischemic injury.

Ziu M, Fletcher L, Rana S, Jimenez DF, Digicaylioglu M - PLoS ONE (2011)

Effects of oxygen-glucose deprivation on miRNA expression in neurons and astrocytes.RNA was isolated from purified cortical neurons or astrocytes that had undergone OGD (1 h) or were maintained in normoxic conditions. RNA concentrations were determined by UV absorbance, and 10 ng for each sample was converted into cDNA and expression levels were measured using RT-PCR[55]. The fold-change in expression of each miRNA compared to that of the normoxic specimen was calculated using 2−ΔC’T formula. Data is expressed as the mean ± the SE (n = 4). The results were analyzed by one-way ANOVA followed by multiple comparisons test (* p<0.05, normoxia versus OGD within each cell type). Differences in the mean expression level for each miRNA between the two different cell types was compared for each time point post-OGD by Student's t test (# p<0.05, astrocyte versus neuron).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044134&req=5

pone-0014724-g001: Effects of oxygen-glucose deprivation on miRNA expression in neurons and astrocytes.RNA was isolated from purified cortical neurons or astrocytes that had undergone OGD (1 h) or were maintained in normoxic conditions. RNA concentrations were determined by UV absorbance, and 10 ng for each sample was converted into cDNA and expression levels were measured using RT-PCR[55]. The fold-change in expression of each miRNA compared to that of the normoxic specimen was calculated using 2−ΔC’T formula. Data is expressed as the mean ± the SE (n = 4). The results were analyzed by one-way ANOVA followed by multiple comparisons test (* p<0.05, normoxia versus OGD within each cell type). Differences in the mean expression level for each miRNA between the two different cell types was compared for each time point post-OGD by Student's t test (# p<0.05, astrocyte versus neuron).
Mentions: MiR-21 was upregulated 1.5-fold at 12 h and 1.94-fold (p<0.05) at 24 h post-OGD as compared to expression in control neurons. MiR-29b showed the highest expression alteration in neurons exposed to OGD. It was upregulated by 1.6-fold at 2 h post-OGD (p<0.05), and 4-fold (p<0.05) at 24 h suggesting a strong involvement of this miRNA in the neuronal response to ischemia. MiR-30b, miR-107 and miR-137 did not alter their expression levels in neurons. MiR-210 was more than 2-fold upregulated at 12 h and 24 h (Figure 1).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America.

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.

Show MeSH
Related in: MedlinePlus