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Quality control of gene expression: mechanisms for recognition and elimination of nonsense mRNA

English title Quality control of gene expression: mechanisms for recognition and elimination of nonsense mRNA
Applicant Mühlemann Oliver
Number 113878
Funding scheme Project funding
Research institution Institut für Zellbiologie Departement Biologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Molecular Biology
Start/End 01.10.2006 - 30.09.2009
Approved amount 335'000.00
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Keywords (6)

nonsense-mediated mRNA decay (NMD); mRNA surveillance; nonsense-mediated transcriptional gene silencing; mRNA turnover; premature termination codon (PTC); quality control of gene expression

Lay Summary (English)

Lead
Lay summary
Complex industrial manufacturing processes require multiple quality control checks along the assembly line to ensure a high proportion of properly functioning final products. Similarly, multiple quality control systems have evolved to recognize mistakes in the intricate chain of complicated biochemical reactions that are involved in the correct expression of the genetic information in each of our cells. Among those, “nonsense-mediated mRNA decay” (NMD) represents quality control mechanism that recognizes and rapidly degrades mRNAs of which the protein coding sequence is truncated by the presence of a premature termination codon (PTC). By eliminating these defective, so-called nonsense mRNAs with crippled protein-coding capacity, NMD substantially reduces the synthesis of potentially deleterious truncated proteins in the cell. Since about 30 % of all known disease-causing mutations in humans lead to the production of a nonsense mRNA, NMD serves as an important modulator of the clinical manifestations of genetic diseases, and manipulating NMD therefore represents a promising strategy for future therapies of many genetic disorders. However, the underlying molecular mechanisms of NMD are currently not well understood. One goal of our basic research is to understand at the molecular level how PTCs are recognized and distinguished from correct termination codons and how this recognition of nonsense mRNAs subsequently triggers their rapid degradation.
In addition to triggering NMD, a post-transcriptional response, we have recently discovered that PTCs in certain immunoglobulin genes can also lead to the transcriptional silencing of the corresponding gene. We are now trying to elucidate the biological relevance of this novel quality control mechanism that we termed “nonsense-mediated transcriptional gene silencing” (NMTGS) and to identify the involved molecules and their interactions.
Methodologically, we mainly use mammalian tissue culture cells to study the effect on the expression of engineered NMD and NMTGS reporter genes upon various treatments of the cells. The effect of known NMD factors and candidate genes is investigated by RNAi-mediated depletion, expression of recombinant proteins, the use of various chemical inhibitors and combinations of these treatments. Biochemical analysis of DNA, RNA and protein involves current state-of-the-art technology, including real-time PCR. In collaboration with laboratories in Montpellier (F) and New York (U.S.A.), we also try to detect normal and nonsense mRNAs in living cells and follow them in real-time and 3D.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
127614 Quality control of gene expression: recognition and elimination of nonsense mRNA 01.10.2009 Project funding
102159 Investigation of the nuclear aspects of nonsense-mediated mRNA decay 01.10.2003 Project funding

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