MicroRNA responses to focal cerebral ischemia in male and female mouse brain

Abstract

Stroke occurs with greater frequency in men than in women across diverse ethnic backgrounds and nationalities. Work from our lab and others have revealed a sex-specific sensitivity to cerebral ischemia whereby males exhibit a larger extent of brain damage resulting from an ischemic event compared to females. Previous studies revealed that microRNA (miRNA) expression is regulated by cerebral ischemia in males; however, no studies to date have examined the effect of ischemia on miRNA responses in females. Thus, we examined miRNA responses in male and female brain in response to cerebral ischemia using miRNA arrays. These studies revealed that in male and female brains, ischemia leads to both a universal miRNA response as well as a sexually distinct response to challenge. Target prediction analysis of the miRNAs increased in male or female ischemic brain reveal sex-specific differences in gene targets and protein pathways. These data support that the mechanisms underlying sexually dimorphic responses to cerebral ischemia includes distinct changes in miRNAs in male and female brain, in addition to a miRNA signature response to ischemia that is common to both.

Keywords: array analysis; cerebral ischemia; microRNA; pathway analysis; qRT-PCR; sex-differences; stroke.

Figure 1

Linear regression analysis of miRNAs altered by ischemia vs. control mouse cortices. The graphs illustrate that there are changes in miRNA expression in ischemia relative to control in male (A) and female (B) mouse cortex. The graphs also show that the majority of the assayed miRNAs are not altered by ischemia.

Figure 2

Classification of miRNAs altered by ischemia. The figure shows the distribution of the miRNAs altered by ischemia relative to control in male and female mouse cortex. For initial studies we focused on miRNAs that were significantly decreased (<−1.5 SD) or increased (>1.5 SD) in the male and female mouse cortex.

Figure 3

Effect of treatment on miRNAs identified as non-changers in male and female mouse cortex. The graphs illustrate that miR-15b^* and miR-125b-3p were not changed significantly in any treatment group in male (A) or female (B) mouse cortex. Control (white bar), sham (gray bar), ischemia (black bar).

Figure 4

Individual microRNAs regulated by ischemia in male and female mouse cortex. The graphs illustrate the ΔΔCt changes for specific miRNAs chosen for further validation by individual qRT-PCR. The graphs show expression of miRNAs in control (white bar) and ischemic (black bar) male (A) or female (B).

Figure 5

Comparison of miRNA array expression to individual qRT-PCR assays in male and female mouse cortex. The graphs show the ΔΔCt of male and female miRNAs control (white bar) or ischemic (black bar) mouse cortex. The graphs also include the ΔΔCt for each miRNA as detected in the miRNA arrays (gray diamond).