MicroRNA Expression Profiling of the Porcine Developing Brain

Abstract

BackgroundMicroRNAs are small, non-coding RNA molecules that regulate gene expression at the post-transcriptional level and play an important role in the control of developmental and physiological processes. In particular, the developing brain contains an impressive diversity of microRNAs. Most microRNA expression profiling studies have been performed in human or rodents and relatively limited knowledge exists in other mammalian species. The domestic pig is considered to be an excellent, alternate, large mammal model for human-related neurological studies, due to its similarity in both brain development and the growth curve when compared to humans. Considering these similarities, studies examining microRNA expression during porcine brain development could potentially be used to predict the expression profile and role of microRNAs in the human brain.Methodology/Principal FindingsMicroRNA expression profiling by use of microRNA microarrays and qPCR was performed on the porcine developing brain. Our results show that microRNA expression is regulated in a developmentally stage-specific, as well as a tissue-specific manner. Numerous developmental stage or tissue-specific microRNAs including, miR-17, miR-18a, miR-29c, miR-106a, miR-135a and b, miR-221 and miR-222 were found by microarray analysis. Expression profiles of selected candidates were confirmed by qPCR.Conclusions/SignificanceThe differential expression of specific microRNAs in fetal versus postnatal samples suggests that they likely play an important role in the regulation of developmental and physiological processes during brain development. The data presented here supports the notion that microRNAs act as post-transcriptional switches which may regulate gene expression when required.

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“…15 During early fetal life, they are highly expressed in the cortex and cerebellum when neuron terminal differentiation is abundant. 16 As the brain develops, they exhibit decreasing expression in the cortex and increasing expression in the cerebellum, in which growth appears later compared with the cortex and continues after birth. 16 These data suggest that mir-221 and mir-222 have a role in the regulation of brain development.…”

“…16 As the brain develops, they exhibit decreasing expression in the cortex and increasing expression in the cerebellum, in which growth appears later compared with the cortex and continues after birth. 16 These data suggest that mir-221 and mir-222 have a role in the regulation of brain development. Interestingly, through the screening of all known brain-expressed X-chromosomal mirRNAs in a cohort of 464 patients with non-syndromic X-linked ID, only four nucleotide changes were identified in three mirRNAs, of Table 2.…”

A Comprehensive Profile of Mature MicroRNA in the Pig

“…Many miRNAs are enriched in reproductive tissues [4,15,17,44] ( Table 3). Others may play a role in differentiating neurons in brain development [3,13,[70][71][72][73]. Several are highly-expressed in big solid organs [1,44,[74][75][76].…”

“…The common research strategy on miRNA may include three aims: (i) characterization of miRNAs (including identification of novel miRNAs), (ii) determination of target genes, and (iii) illumination of function of miRNAs and target genes. These strategies have been widely used to describe the miRNAome in various pig tissues, such as muscle [9][10][11][12], brain [13], fat [14], embryo [3], pituitary [15], intestine [16], ovary [17] and testes [4].…”

Expression and Regulation Profile of Mature MicroRNA in the Pig: Relevance to Xenotransplantation

“…These strategies have been widely used to describe the miRNAome in various pig tissues, such as muscle [9][10][11][12] , brain 13 , fat 14 , embryo 3 , pituitary 15 , intestine 16 , ovary 17 and testes 4 . This review is focused on the possible functions and regulating mechanisms of miRNAs in pigs, aiming towards a better understanding of the miRNAome in various tissues.…”