Altered MicroRNA Expression in Intracranial Aneurysmal Tissues: Possible Role in TGF-β Signaling Pathway

Abstract

The molecular mechanisms behind the rupture of intracranial aneurysms remain obscure. MiRNAs are key regulators of a wide array of biological processes altering protein synthesis by binding to target mRNAs. However, variations in miRNA levels in ruptured aneurysmal wall have not been completely examined. We hypothesized that altered miRNA signature in aneurysmal tissues could potentially provide insight into aneurysm pathophysiology. Using a high-throughput miRNA microarray screening approach, we compared the miRNA expression pattern in aneurysm tissues obtained during surgery from patients with aneurysmal subarachnoid hemorrhage (aSAH) with control tissues (GEO accession number GSE161870). We found that the expression of 70 miRNAs was altered. Expressions of the top 10 miRNA were validated, by qRT-PCR and results were correlated with clinical characteristics of aSAH patients. The level of 10 miRNAs (miR-24-3p, miR-26b-5p, miR-27b-3p, miR-125b-5p, miR-143-3p, miR-145-5p, miR-193a-3p, miR-199a-5p, miR-365a-3p/365b-3p, and miR-497-5p) was signi cantly decreased in patients compared to controls. Expression of miR-125b-5p, miR-143-3p and miR-199a-5p was signi cantly decreased in patients with poor prognosis and vasospasm. The target genes of few miRNAs were enriched in Transforming growth factor-beta (TGF-β) and Mitogen-activated protein kinases (MAPK) pathways. We found signi cant negative correlation between the miRNA and mRNA expression (TGF-β1, TGF-β2, SMAD family member 2 (SMAD2), SMAD family member 4 (SMAD4), MAPK1 and MAPK3) in aneurysm tissues. We suggest that miR-26b, miR-199a, miR-497and miR-365, could target multiple genes in TGF-β and MAPK signaling cascades to in uence in ammatory processes, extracellular matrix and vascular smooth muscle cell degradation and apoptosis, and ultimately cause vessel wall degradation and rupture.

MicroRNAs as Biomarkers for Predicting Complications following Aneurysmal Subarachnoid Hemorrhage

“…It is worth mentioning that many of these differentially expressed miRNAs (including miR-143, miR-145, miR-21, miR-26, miR-29a/b, miR-146a, miR-155, miR-133a, miR-133b, and let-7 family) are also altered in abdominal aortic aneurysmal tissues [50][51][52][53] suggesting a common mechanism. Interestingly, the levels of several miRNAs (e.g., miR-143, miR-145, and miR-23b) were found to be consistently down-regulated among the studies described above [30,45,47,54]. For example, miR-23b was reduced in IA tissues and was reported to target phosphatase and tensin homolog (PTEN) [55], a key regulator of proliferation, differentiation, and cytokine production during pathological vascular remodeling in smooth muscle cells [56].…”

“…In addition, miRNAs are aberrantly expressed in the vascular walls following injury [42]. Several studies have confirmed that miRNAs are dysregulated in intracranial aneurysms (Table 1) [30,[44][45][46][47][48]. In 2014, Liu et al reported that over 150 miRNAs were differentially expressed in aneurysmal arteries compared to normal arteries [30], demonstrating both patterns of up-and down-regulation of various miRNAs.…”

“…Specifically, Liu et al used the extracranial superficial temporal artery; whereas, Jiang et al used the intracranial middle meningeal artery. In addition, a recent study by Supriya et al, employed intercostal artery as the sampling site for control specimens and identified 70 dysregulated miRNAs in aSAH [47]. Unlike the above-mentioned studies that analyzed ruptured aneurysmal tissue, Bekelis et al utilized unruptured aneurysms to investigate miRNAs as well as protein coding genes in the same specimen.…”

“…For example, miR-23b was reduced in IA tissues and was reported to target phosphatase and tensin homolog (PTEN) [55], a key regulator of proliferation, differentiation, and cytokine production during pathological vascular remodeling in smooth muscle cells [56]. MiR-143 and miR-145 play an important role in controlling vascular smooth muscle phenotype by maintaining or inhibiting differentiation [28,57] and were found to be significantly down-regulated in IA tissues and plasma [30,44,45,47,54,57]. Consistent with a decrease in miR-143 and miR-145, their predicted target genes, including those involved in extracellular matrix remodeling, collagen synthesis, and metabolism (ADAMTS2, COL1A1, COL5A1, and COL5A2), were significantly up-regulated in the same tissues [44].…”

“…miRNAs are recognized as powerful regulators of central nervous system (CNS) inflammatory responses [32], including inflammation that occurs following ischemic stroke and aSAH [29,[62][63][64]. For example, miR-125b was shown to be reduced in IA tissues [30,47,48], which may target nitric oxide synthase 1 (NOS1) and contribute to macrophage-mediated vascular smooth muscle cell apoptosis [65]. MiR-155 is a major inflammatory responsive miRNA that is immune cell-specific and highly inducible [32].…”