MicroRNA-130a associates with ribosomal protein L11 to suppress c-Myc expression in response to UV irradiation
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Yuhuang Li1, Kishore B. Challagundla1, Xiao-Xin Sun1, Qinghong Zhang2, Mu-Shui Dai1
1Departments of Molecular & Medical Genetics, School of Medicine and the OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, OR 97239, USA
2Department of Dermatology, University of Colorado, Denver, Aurora, CO 80045, USA
Mu-Shui Dai, e-mail: email@example.com
Keywords: miR-130a, L11, c-Myc, microRNA, UV irradiation
Received: September 17, 2014 Accepted: November 08, 2014 Published: December 31, 2014
The oncoprotein c-Myc is essential for cell growth and proliferation while its deregulated overexpression is associated with most human cancers. Thus tightly regulated levels and activity of c-Myc are critical for maintaining normal cell homeostasis. c-Myc is down-regulated in response to several types of stress, including UV-induced DNA damage. Yet, mechanism underlying UV-induced c-Myc reduction is not completely understood. Here we report that L11 promotes miR-130a targeting of c-myc mRNA to repress c-Myc expression in response to UV irradiation. miR-130a targets the 3’-untranslated region (UTR) of c-myc mRNA. Overexpression of miR-130a promotes the Ago2 binding to c-myc mRNA, significantly reduces the levels of both c-Myc protein and mRNA and inhibits cell proliferation. UV treatment markedly promotes the binding of L11 to miR-130a, c-myc mRNA as well as Ago2 in cells. Inhibiting miR-130a significantly suppresses UV-mediated c-Myc reduction. We further show that L11 is relocalized from the nucleolus to the cytoplasm where it associates with c-myc mRNA upon UV treatment. Together, these results reveal a novel mechanism underlying c-Myc down-regulation in response to UV-mediated DNA damage, wherein L11 promotes miR-130a-loaded miRISC to target c-myc mRNA.
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