Upregulation of miR-499a Targets Beclin1 to Modulate Astrocyte Autophagy and Promote Ischemic Stroke

To investigate the clinical significance of miR-499a expression in the serum of ischemic stroke patients and its potential mechanism in regulating astrocytes to promote ischemic stroke.

Serum samples from 99 ischemic stroke patients and 99 healthy individuals were collected and analyzed for miR-499a expression through RT-PCR. Statistical analysis was performed to compare the expression differences between the two groups, and correlation between miR-499a expression and clinical pathological indices in stroke patients was analyzed. MiR-499a mimic, inhibitor, and negative control vectors were constructed and transfected into astrocyte SVGp12 cells. Afterward, miR-499a expression was validated by RT-PCR, cell viability was assessed by CCK8 assay, and apoptosis was detected using flow cytometry. The binding sites of miR-499a and Beclin1 were predicted by the Target-scan database and confirmed by dual luciferase assay. After overexpressing Beclin1, co-transfection with miR-499a mimic or negative control was conducted to observe the reverse effect of miR-499a mimic on Beclin1 overexpression.

MiR-499a was significantly upregulated in the stroke group (p<0.001), it was positively correlated with TC (Total Cholesterol), LDL-C (Low-density lipoprotein cholesterol), and APO-A1 (Apolipoprotein A1) (R²>0.3, p<0.001). MiR-499a mimics promoted cell viability while inhibiting apoptosis of astrocytes. MiR-499a targeted Beclin 1 and inhibited its mRNA and protein expression, as well as the expression of autophagy-related proteins LC-3 and p62. MiR-499a could reverse the impact of Beclin1 overexpression on SVGp12 astrocyte proliferation and apoptosis.

Serum miR-499a in stroke patients may serve as a potential diagnostic indicator. MiR-499a-mediated inhibition of Beclin 1, subsequently leading to suppression of astrocytic autophagy and viability, may represent a pivotal mechanism underlying its promotion of IS.