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The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila.

ABSTRACT: Human neurodegenerative diseases have the temporal hallmark of afflicting the elderly population. Ageing is one of the most prominent factors to influence disease onset and progression, yet little is known about the molecular pathways that connect these processes. To understand this connection it is necessary to identify the pathways that functionally integrate ageing, chronic maintenance of the brain and modulation of neurodegenerative disease. MicroRNAs (miRNA) are emerging as critical factors in gene regulation during development; however, their role in adult-onset, age-associated processes is only beginning to be revealed. Here we report that the conserved miRNA miR-34 regulates age-associated events and long-term brain integrity in Drosophila, providing a molecular link between ageing and neurodegeneration. Fly mir-34 expression exhibits adult-onset, brain-enriched and age-modulated characteristics. Whereas mir-34 loss triggers a gene profile of accelerated brain ageing, late-onset brain degeneration and a catastrophic decline in survival, mir-34 upregulation extends median lifespan and mitigates neurodegeneration induced by human pathogenic polyglutamine disease protein. Some of the age-associated effects of miR-34 require adult-onset translational repression of Eip74EF, an essential ETS domain transcription factor involved in steroid hormone pathways. Our studies indicate that miRNA-dependent pathways may have an impact on adult-onset, age-associated events by silencing developmental genes that later have a deleterious influence on adult life cycle and disease, and highlight fly miR-34 as a key miRNA with a role in this process.

SUBMITTER: Liu N

PROVIDER: S-EPMC3326599 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila.

Liu Nan N Landreh Michael M Cao Kajia K Abe Masashi M Hendriks Gert-Jan GJ Kennerdell Jason R JR Zhu Yongqing Y Wang Li-San LS Bonini Nancy M NM

Nature 20120215 7386

Human neurodegenerative diseases have the temporal hallmark of afflicting the elderly population. Ageing is one of the most prominent factors to influence disease onset and progression, yet little is known about the molecular pathways that connect these processes. To understand this connection it is necessary to identify the pathways that functionally integrate ageing, chronic maintenance of the brain and modulation ...[more]

PMID: 22343898

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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.

Project description:BackgroundMicroRNAs (miRNAs) have been implicated in cancer initiation and progression via their ability to affect expression of genes and proteins that regulate cell proliferation and/or cell death. Transcription of the three miRNA miR-34 family members was recently found to be directly regulated by p53. Among the target proteins regulated by miR-34 are Notch pathway proteins and Bcl-2, suggesting the possibility of a role for miR-34 in the maintenance and survival of cancer stem cells.Methodology/principal findingsWe examined the roles of miR-34 in p53-mutant human pancreatic cancer cell lines MiaPaCa2 and BxPC3, and the potential link to pancreatic cancer stem cells. Restoration of miR-34 expression in the pancreatic cancer cells by either transfection of miR-34 mimics or infection with lentiviral miR-34-MIF downregulated Bcl-2 and Notch1/2. miR-34 restoration significantly inhibited clonogenic cell growth and invasion, induced apoptosis and G1 and G2/M arrest in cell cycle, and sensitized the cells to chemotherapy and radiation. We identified that CD44+/CD133+ MiaPaCa2 cells are enriched with tumorsphere-forming and tumor-initiating cells or cancer stem/progenitor cells with high levels of Notch/Bcl-2 and loss of miR-34. More significantly, miR-34 restoration led to an 87% reduction of the tumor-initiating cell population, accompanied by significant inhibition of tumorsphere growth in vitro and tumor formation in vivo.Conclusions/significanceOur results demonstrate that miR-34 may restore, at least in part, the tumor suppressing function of the p53 in p53-deficient human pancreatic cancer cells. Our data support the view that miR-34 may be involved in pancreatic cancer stem cell self-renewal, potentially via the direct modulation of downstream targets Bcl-2 and Notch, implying that miR-34 may play an important role in pancreatic cancer stem cell self-renewal and/or cell fate determination. Restoration of miR-34 may hold significant promise as a novel molecular therapy for human pancreatic cancer with loss of p53-miR34, potentially via inhibiting pancreatic cancer stem cells.

Dataset Information

The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila.

Publications

The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila.

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