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Nonsense mediated decay downregulates conserved alternatively spliced ABCC4 transcripts bearing nonsense codons
Jatinder Kaur Lamba1, Masashi Adachi, Daxi Sun
1St Jude Children's Research Hospital, Department of Pharmaceutical Sciences, Memphis, TN, USA.
Human Molecular Genetics
|December 25, 2002
Summary
The study reveals that conserved premature termination codon (PTC) exons in the ABCC4 gene may regulate its expression through nonsense-mediated mRNA decay (NMD). This mechanism impacts cellular defense against drugs by controlling ABCC4 (multidrug resistance-associated protein 4) levels.
Area of Science:
- Molecular Biology
- Genetics
- Pharmacology
Background:
- Drug transporters, like multidrug resistance-associated proteins (MRPs; ABCC gene family), are crucial for cellular defense against cytotoxic agents.
- ABCC4 (MRP4) is an ATP-binding cassette transporter that effluxes anti-HIV drugs, antiviral nucleotides, and anti-cancer agents.
Purpose of the Study:
- To investigate the functional consequences of an insertion in ABCC4 cDNA and determine the ABCC4 gene structure.
- To explore the evolutionary conservation and regulatory mechanisms of ABCC4 expression, particularly concerning premature termination codons (PTCs).
Main Methods:
- Isolation and characterization of ABCC4 cDNA and gene structure.
- Comparative analysis of human, monkey, and rodent ABCC4 genes.
- Investigation of nonsense-mediated mRNA decay (NMD) using protein synthesis inhibition in cell lines.
Main Results:
- An insertion in ABCC4 cDNA led to premature termination codons (PTCs).
- PTC-producing exons are highly conserved across human, monkey, and rodent ABCC4 genes.
- PTC-containing ABCC4 transcripts are stabilized by protein synthesis inhibition and are targets of NMD.
Conclusions:
- Highly conserved PTC exons in the ABCC4 gene likely regulate its expression.
- Nonsense-mediated mRNA decay (NMD) plays a significant role in controlling ABCC4 transcript levels.
- This regulatory mechanism may influence cellular responses to various therapeutic agents.