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The Expression of MicroRNA and microRNA Clusters in the Aging Heart

ABSTRACT: Adult aging is a complex biological process associated with altered gene expression and a decline in physiological performance. The microRNAs have been implicated in cardiac development, cardiac hypertrophy and heart failure. However, the impact of adult aging on cardiac expression of both miRNA guide strand (miR) and passenger strand (miR*), as well as miRNA clusters have not been well established. We explored the expression profile of both miR and miR* in the heart. We found that 65 miRNAs were differentially expressed in old versus young adult heart; approximately half of them were clustered miRNAs that were distributed in 11 miRNA clusters. Each miRNA cluster contains from 2 to as many as 71 miRNA genes. The majority of the clusters displayed unified expression, with most cluster members within a cluster being either increased or decreased together, suggesting that most clusters are regulated by a common signaling mechanism and that the combined expression of multiple miRNA genes in a cluster could pose an impact on a broad range of targets during aging. We also found age-related changes in the expression of miR*s. Bioinformatic analysis revealed that miR-21 and miR-21* had their own silencing targets. The expression of both miR and miR* correlated with that of pri-miRNA transcript over the time course from development and maturation through adult aging. Age-related changes in the expression of Ago1 and Ago2 proteins in the heart were also observed. Our data suggest that a concert of effects, including transcriptional regulation of pri-miRNA transcript and altered expression of Argonaut proteins, contribute to age-related changes in the expression of both miR and miR* strands during adult aging. The major changes occurred later in life, from middle to old age. It is likely that the expression of both miR and miR* is regulated by transcription and Ago1 and Ago2 proteins.

ORGANISM(S): Mus musculus

PROVIDER: GSE32935 | GEO | 2012/08/20

SECONDARY ACCESSION(S): PRJNA146567

REPOSITORIES: GEO

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Project description:Adult aging is a complex biological process associated with altered gene expression and a decline in physiological performance. The microRNAs have been implicated in cardiac development, cardiac hypertrophy and heart failure. However, the impact of adult aging on cardiac expression of both miRNA guide strand (miR) and passenger strand (miR*), as well as miRNA clusters have not been well established. We explored the expression profile of both miR and miR* in the heart. We found that 65 miRNAs were differentially expressed in old versus young adult heart; approximately half of them were clustered miRNAs that were distributed in 11 miRNA clusters. Each miRNA cluster contains from 2 to as many as 71 miRNA genes. The majority of the clusters displayed unified expression, with most cluster members within a cluster being either increased or decreased together, suggesting that most clusters are regulated by a common signaling mechanism and that the combined expression of multiple miRNA genes in a cluster could pose an impact on a broad range of targets during aging. We also found age-related changes in the expression of miR*s. Bioinformatic analysis revealed that miR-21 and miR-21* had their own silencing targets. The expression of both miR and miR* correlated with that of pri-miRNA transcript over the time course from development and maturation through adult aging. Age-related changes in the expression of Ago1 and Ago2 proteins in the heart were also observed. Our data suggest that a concert of effects, including transcriptional regulation of pri-miRNA transcript and altered expression of Argonaut proteins, contribute to age-related changes in the expression of both miR and miR* strands during adult aging. The major changes occurred later in life, from middle to old age. It is likely that the expression of both miR and miR* is regulated by transcription and Ago1 and Ago2 proteins. Six healthy C57BL/6 mice were used in this study. Three of them were 4 months old (young adult mice: YA), and the other three were 24 months old (old mice). Total RNA samples were isolated from mouse hearts and then shipped to Exiqon Inc., where microRNA array analysis was performed. Three array slides were used for the hybridization. Each array slide hybridized with two samples labeld with either Hy3 or Hy5, with array #1 being hybridized with samples YA-1 (Hy3) and Old-1 (Hy5), array #2 with samples YA-2 (Hy3) and Old-2 (Hy5) and array #3 with samples YA-3 (Hy5) and Old-3 (Hy3). In our publication, we reveal the detail of the experiment and statistical analysis that were provided by Exiqon Inc.

Project description:This SuperSeries is composed of the following subset Series: GSE24992: Drosophila brain microRNA expression with age: miRNA profiling GSE25007: Drosophila brain gene expression with age: mRNA profiling GSE25008: Drosophila brain gene expression between wildtype and miR-34 null flies Refer to individual Series. Aging is the most prominent risk factor for human neurodegenerative disease, but underlying mechanisms that connect two processes are less well characterized. With age, the brain undergoes functional decline and perhaps degeneration. Such decline may not just contribute to normal aging, but also enhance susceptibility to and progression of age-related neurodegenerative diseases. Therefore, defining intrinsic factors and pathways that underline the normal integrity of the adult nervous system may lead to insights that potentially link aging and neurodegeneration. Here, we report a highly conserved microRNA (miRNA), miR-34, as a modulator of aging and neurodegeneration. Using Drosophila, we show that fly miR-34 expression is brain-enriched and strikingly upregulated with age. Functional studies reveal that, whereas animals without miR-34 are normal as young adults, upon aging, they gradually show late-onset deficits characteristic of accelerated brain aging; these include a transcriptional signature of aged animals, coupled with rapid functional decline, loss of brain integrity, followed by a catastrophic decline in adult viability. Moreover, upregulation of miR-34 protects against neurodegeneration induced by pathogenic human polyglutamine (polyQ) disease protein. We next reveal a dramatic effect of miR-34 to silence the Eip74EF gene of steroid hormone pathways in the adult, which is crucial to maintain the normal aging. Collectively, these data define a miR-34-mediated mechanism that specifically affects long-term integrity of the adult nervous system. miR-34 function in Drosophila may thus present a link that functionally connects aging and neurodegeneration. Our studies implicate essential roles of miRNA- dependent pathways in maintenance of the adult brain, disease pathogenesis and healthy aging.

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The Expression of MicroRNA and microRNA Clusters in the Aging Heart

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