%0 Journal Article
%T MicroRNAs in Cerebral Ischemia
%A Yang Wang
%A Yongting Wang
%A Guo-Yuan Yang
%J Stroke Research and Treatment
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/276540
%X The risk of ischemic stroke increases substantially with age, making it the third leading cause of death and the leading cause of long-term disability in the world. Numerous studies demonstrated that genes, RNAs, and proteins are involved in the occurrence and development of stroke. Current studies found that microRNAs (miRNAs or miRs) are also closely related to the pathological process of stroke. miRNAs are a group of short, noncoding RNA molecules playing important role in posttranscriptional regulation of gene expression and they have emerged as regulators of ischemic preconditioning and ischemic postconditioning. Here we give an overview of the expression and function of miRNAs in the brain, miRNAs as biomarkers during cerebral ischemia, and clinical applications and limitations of miRNAs. Future prospects of miRNAs are also discussed. 1. Introduction miRNAs are approximately 20-nucleotide, single-stranded RNA molecules that target mRNA through partial complementarity and they can regulate gene expression through inhibition of translation or transcript degradation [1]. It is now predicted that 40% to 50% of mammalian mRNAs could be regulated at the translational level by miRNAs [2]. In mammals, specific miRNAs are known to control processes including development, neuronal cell fate, apoptosis, proliferation, adipocyte differentiation, hematopoiesis, and exocytosis as well as in diseases [3¨C5] and possibly neuronal disorders [6]. miRNA expression has been detected in stroke [2, 7], Alzheimer¡¯s disease [8], Parkinson¡¯s disease [9], Down¡¯s syndrome [10], and schizophrenia [11]. These miRNAs expression profiles may be as diagnostically useful as mRNA expression profiles [12]. In the nucleus, miRNAs are transcribed as hairpin clusters of primary miRNAs (pri-miRNAs; 5¡ä-capped polyadenylated transcripts), which is converted to 70-nt stem loop structures (pre-miRNAs) by Drosha (a type-III RNase) in association with a cofactor Pasha (aka DiGeorge syndrome critical region gene 8) [13]. pre-miRNAs are transported from nucleus to cytosol by exportin-5 and acted on by another type-III RNase known as Dicer that deletes the terminal loop of pre-miRNAs to form mature miRNAs [14]. 2. miRNA Expression and Its Functions in the Brain miRNAs serve important roles in the development and function of the brain [15¨C19]. Studies support that tissue-specific miRNAs contribute to establish and maintain protein expression profiles underlying distinct cellular phenotypes. The discovery of seven brain-specific miRNAs (miR-9, miR-124a, miR-124b, miR-135, miR-153, miR-183, and
%U http://www.hindawi.com/journals/srt/2013/276540/