Stem cell division is regulated by the microRNA pathway (Nature, 435:974-978, 16 June 2005)

報告日期: 2005/10/18
報告時間: 15:10/16:00
報告學生: 楊瑞珠
講評老師: 張文粲
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Stem cell division is regulated by the microRNA pathway

Nature 435: 974 – 978 (2005)

 

Speaker: 楊瑞珠                  Time: 18/10/2005 15:10~16:00

Commentator: 張文粲 老師         Place: Room 602

 

Abstract:

MicroRNAsmiRNAsare a family of small, non-coding RNAs that regulate gene expression and are processed by the enzyme Dicer. Recent studies revealed that miRNAs may contribute to the self-renewal of stem cells in plants and animals. Until now, it is still a mystery about how stem cells remain continuous division in a microenvironment of most cells are quiescent. In this study, the authors aim to clarify the role of miRNAs in the control of stem cell division. Firstly, the author disrupted the miRNAs pathway by using a dicer-1dcr-1 mutant in germline stem cell GSCof Drosophila melanogaster. Loss of dcr-1 function led to the reduction of egg chamber production, without affected their normal development. In addition, the division frequency and the number of germline cysts in the dcr-1 mutant were also decreased. The dcr-1 mutant GSCs have shown increased Cyclin E but reduced Cyclin A, Cyclin B, mitotic marker Phosphohistone-3 and BrdU, indicating that these GSCs were arrested in the G1/S transition. The bypass of G1/S checkpoint in Drosophila is regulated by the cyclin-dependent kinase inhibitor Dacapo, which is increased in the dcr-1 mutant GSCs. Hence, miRNAs may act on stem cell division by reducing the levels of Dacapo. In conclusion, these data suggested that miRNAs may promote the stem cell renewal, which is independent of environment signals, by contributing to the escape of G1/S checkpoint.

References:

1. He, L. & Hannon, G. J. MicroRNAs: small RNAs with a big role in gene regulation.         Nature Rev. Genet. 5, 522−531 (2004) 

2. Spradling, A., Drummond-Barbosa, D. & Kai, T. Stem cells find their niche. Nature 414, 98−104 (2001)