Our major goal is to understand how the levels of mRNAs encoding cytokines and oncoproteins are regulated, because sustained synthesis of these gene products can favor cell growth rather than differentiation, a hallmark of the neoplastic phenotype. Many cytokine and proto-oncogene mRNAs exhibit extremely short half-lives which limits their use as templates for translation. Moreover, the half-lives of their mRNAs are frequently subject to regulatory control. Their decay is controlled in part by A+U-rich elements (AREs) located in the 3'-UTR. AREs target mRNAs for rapid degradation usually via a sequential, 3'-to-5' pathway involving rapid removal of the poly(A) tract followed by degradation of the mRNA body. Candidate 3'-5' activities include a deadenylase, such as PARN; the exosome, which is a large complex of exoribonucleases; and the proteasome, which appears to possess an ARE-specific ribonuclease activity. We are interested in why and how AREs target mRNAs for rapid degradation and what factors are involved in this process. Toward these ends, we utilized a previously described cell-free mRNA decay system, which reconstitutes cellular decay processes, to biochemically dissect the degradation machinery. We identified and purified the ARE-binding factor AUF1 from K562 cells, a human chronic myeloid leukemia cell line Ectopic expression of AUF1 reverses the inactivation of ARE-directed mRNA decay in hemin-treated K562 cells, supporting an in vivo role for AUF1 in mRNA destabilization. In cells AUF1 exists in complexes with other cellular proteins, such as the translation initiation factor eIF4G, the hspfhsc7O heat shock proteins, and poly(A)binding protein. AUF1 is also ubiquitinated. Under the stress of cell culture at elevated temperatures, heat shock proteins like hsp7O may prevent AUF1 from recruiting the mRNP to both the ubiquitin-proteasome pathway and ribonucleolytic degradation activities resulting in stabilization of ARE-mRNAs. Thus, our central hypothesis is that binding of AUF1 to an ARE promotes the assembly of an mRNA-protein complex that recruits the proteasome and ribonucleolytic activities to the mRNA for its destruction. We plan to utilize our cell-free mRNA decay system along with the reagents and expertise gained from our studies of AUF1 so far to further test, validate, refine, and if necessary, modify our central hypothesis of AUF1 function.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA052443-12
Application #
6686332
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Mietz, Judy
Project Start
1990-07-01
Project End
2006-11-30
Budget Start
2003-12-01
Budget End
2004-11-30
Support Year
12
Fiscal Year
2004
Total Cost
$341,980
Indirect Cost
Name
University of Medicine & Dentistry of NJ
Department
Genetics
Type
Schools of Medicine
DUNS #
617022384
City
Piscataway
State
NJ
Country
United States
Zip Code
08854
Lin, Hsin-Ching; Simon, Peter J; Ysla, Riza M et al. (2017) RNA stability regulates human T cell leukemia virus type 1 gene expression in chronically-infected CD4 T cells. Virology 508:7-17
Li, Mei-Ling; Weng, Kuo-Feng; Shih, Shin-Ru et al. (2016) The evolving world of small RNAs from RNA viruses. Wiley Interdiscip Rev RNA 7:575-88
Lin, Jing-Yi; Brewer, Gary; Li, Mei-Ling (2015) HuR and Ago2 Bind the Internal Ribosome Entry Site of Enterovirus 71 and Promote Virus Translation and Replication. PLoS One 10:e0140291
Lin, Jing-Yi; Li, Mei-Ling; Brewer, Gary (2014) mRNA decay factor AUF1 binds the internal ribosomal entry site of enterovirus 71 and inhibits virus replication. PLoS One 9:e103827
Kishor, Aparna; Tandukar, Bishal; Ly, Yann V et al. (2013) Hsp70 is a novel posttranscriptional regulator of gene expression that binds and stabilizes selected mRNAs containing AU-rich elements. Mol Cell Biol 33:71-84
White, Elizabeth J F; Brewer, Gary; Wilson, Gerald M (2013) Post-transcriptional control of gene expression by AUF1: mechanisms, physiological targets, and regulation. Biochim Biophys Acta 1829:680-8
Li, Mei-Ling; Defren, Jennifer; Brewer, Gary (2013) Hsp27 and F-box protein ýý-TrCP promote degradation of mRNA decay factor AUF1. Mol Cell Biol 33:2315-26
Wu, Xiangyue; Chesoni, Sandra; Rondeau, Gaelle et al. (2013) Combinatorial mRNA binding by AUF1 and Argonaute 2 controls decay of selected target mRNAs. Nucleic Acids Res 41:2644-58
Qi, Mei-Yan; Wang, Zhi-Zhang; Zhang, Zhuo et al. (2012) AU-rich-element-dependent translation repression requires the cooperation of tristetraprolin and RCK/P54. Mol Cell Biol 32:913-28
Xin, Hong; Brown, Julie A; Gong, Changning et al. (2012) Association of the von Hippel-Lindau protein with AUF1 and posttranscriptional regulation of VEGFA mRNA. Mol Cancer Res 10:108-20

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