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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

microRNA-93 packaged in extracellular vesicles from mesenchymal stem cells reduce neonatal hypoxic-ischemic brain injury.

OBJECTIVE: Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been proposed as a promising strategy for treating ischemia-related diseases. Herein, we probed into the role of miR-93 delivered by BMSC-EVs in hypoxic-ischemic brain injury (HIBD). METHODS: Neonatal HIBD mouse models and hippocampal neuron models of oxygen glucose deprivation (OGD) were constructed. EVs were isolated from the culture medium of bone marrow MSCs (BMSCs). After co-culture of BMSC-EVs with OGD-exposed hippocampal neurons, the effect of microRNA-93 (miR-93) delivered by BMSC-EVs on OGD-induced hippocampal neurons as well as on HIBD in vivo under transfection of miR-93 mimic or inhibitor was explored. The interaction among miR-93, JMJD3, and p53/KLF2 axis was assessed. RESULTS: BMSC-EVs prevented OGD-induced hippocampal neuron apoptosis and inflammation, which was associated with their transfer of miR-93 into the hippocampal neurons. miR-93 targeted JMJD3 and downregulated its expression, thus inhibiting the OGD-induced hippocampal neuron apoptosis. By regulating the JMJD3/p53/KLF2 axis, miR-93 in BMSC-EVs reduced the OGD-induced hippocampal neuron apoptosis in vitro as well as alleviating HIBD in vivo. CONCLUSIONS: The current study highlighted that miR-93 delivered by BMSC-EVs alleviated HIBD in neonatal mice through the JMJD3-dependent p53/KLF2 axis.

Role of long noncoding RNA MEG3/miR-378/GRB2 axis in neuronal autophagy and neurological functional impairment in ischemic stroke.

Autophagy has been shown to maintain neural system homeostasis during stroke. However, the molecular mechanisms underlying neuronal autophagy in ischemic stroke remain poorly understood. This study aims to investigate the regulatory mechanisms of the pathway consisting of MEG3 (maternally expressed gene 3), microRNA-378 (miR-378), and GRB2 (growth factor receptor-bound protein 2) in neuronal autophagy and neurological functional impairment in ischemic stroke. A mouse model of the middle cerebral artery occluded-induced ischemic stroke and an in vitro model of oxygen-glucose deprivation-induced neuronal injury were developed. To understand the role of the MEG3/miR-378/GRB2 axis in the neuronal regulation, the expression of proteins associated with autophagy in neurons was measured by Western blotting analysis, and neuron death was evaluated using a lactate dehydrogenase leakage rate test. First, it was found that the GRB2 gene, up-regulated in middle cerebral artery occluded-operated mice and oxygen-glucose deprivation-exposed neurons, was a target gene of miR-378. Next, miR-378 inhibited neuronal loss and neurological functional impairment in mice, as well as neuronal autophagy and neuronal death by silencing of GRB2. Confirmatory in vitro experiments showed that MEG3 could specifically bind to miR-378 and subsequently up-regulate the expression of GRB2, which in turn suppressed the activation of Akt/mTOR pathway. Taken together, these findings suggested that miR-378 might protect against neuronal autophagy and neurological functional impairment and proposed that a MEG3/miR-378/GRB2 regulatory axis contributed to better understanding of the pathophysiology of ischemic stroke.

Impact of genotype on endocrinal complications of Children with Alpha-thalassemia in China.

Alpha-thalassemia occurs with high frenquency in China. Four common α-globin gene deletion mutations (-SEA, -α3.7, and -α4.2, Haemoglobin Constant Spring (CS) mutation) were identified in Chinese patients. Individuals with alpha-thalassemia syndrome are more often of children. However report on endocrinal complications in children with alpha thalassemia in China are still absent. The present study aimed to investigate the impact of genotype on endocrinal complications in Chinese children. Association analysis between genotype and endocrinal compliaction development was conducted on 200 patients with 200 healthy controls. Hypogonadism was found to be the most prominent endocrinal complications (84.0%) leading to the growth retardation, hypogonadism, diabetes mellitus, hypothyroidism and hypoparathyroidism whose incidence were significantly higher in pateints. (αCSα/-SEA) was the main genotype of Alpha thalassemia identified in the patients (37.5%), and patients with the (-α4.2/-SEA) genotype had a higher prevalence of hypogonadism, diabetes mellitus and hypoparathyroidism (P = 0.001, P = 0.001, P < 0.001, respectively).