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Molecular cloning of ADIR, a novel interferon responsive gene encoding a protein related to the torsins
Michel Dron1, Jean François Meritet, Françoise Dandoy-Dron
1Laboratory of Viral Oncology CNRS UPR 9045, Institute André Lwoff, Villejuif Cedex, 94801, France.
Abstract:
The expression of the previously uncharacterized gene Adir (for ATP dependent interferon responsive gene) was increased by 5- to 15-fold in tissue of the oral cavity or in spleen and liver of mice treated orally or intraperitoneally with IFN-alpha, and in mouse cells treated in vitro with IFN-alpha or IFN-gamma. The level of Adir mRNA was also increased 20- to 40-fold in the brains of animals infected with encephalomyocarditis virus. Adir is expressed ubiquitously in mouse tissues as 1.9-, 2.4-, and 3.5-kb mRNA transcripts encoding a 385-amino-acid protein with a conserved ATP binding domain containing typical nucleotide and Mg(2+) binding sites. We also characterized the human ortholog, ADIR, which is located on chromosome 1q25-q31 and contains six exons encoding a 397-amino-acid protein with 80% homology to the mouse protein. A single 2.3-kb mRNA was detected in all human tissues examined, except for placenta, which also contained a 1.25-kb tissue-specific transcript generated by alternative splicing and encoding a putative 336-amino-acid protein. Although ADIR exhibits low homology to DYT1 and TOR1B, the deduced ADIR protein sequences are highly homologous to torsin A and torsin B and more distantly related to members of the Clp/HSP100 family of proteins, suggesting that ADIR, like torsins, is related to the AAA chaperone-like family of ATPases. An ADIR-EGFP fusion protein expressed in HeLa cells was shown to be associated with the endoplasmic reticulum.
Insights
The newly identified ATP dependent interferon responsive gene (Adir) shows increased expression in response to interferon and viral infection. This gene encodes a protein similar to AAA chaperones, suggesting a role in cellular processes.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- The interferon system is crucial for antiviral defense.
- The characterization of interferon-responsive genes is vital for understanding immune mechanisms.
- The Adir gene was previously uncharacterized.
Purpose of the Study:
- To characterize the Adir gene and its protein product.
- To investigate the regulation of Adir expression.
- To determine the evolutionary relationship and cellular localization of Adir.
Main Methods:
- Quantitative analysis of Adir mRNA levels in mouse tissues and cells.
- In vitro treatment of cells with interferons (IFN-alpha, IFN-gamma).
- Viral infection models (encephalomyocarditis virus).
- Sequence analysis and homology searches.
- Expression of fusion proteins (ADIR-EGFP) in human cell lines (HeLa).
Main Results:
- Adir expression increased 5- to 15-fold in mice and cells treated with IFN-alpha or IFN-gamma.
- Adir mRNA levels increased 20- to 40-fold in the brains of virus-infected mice.
- Adir encodes a protein with an ATP binding domain, homologous to torsins and related to AAA chaperones.
- The human ortholog ADIR is located on chromosome 1q25-q31 and shows alternative splicing in placenta.
- ADIR-EGFP fusion protein localized to the endoplasmic reticulum.
Conclusions:
- Adir is a novel interferon-responsive gene with ubiquitous expression in mice.
- The Adir protein belongs to the AAA chaperone-like family of ATPases.
- The human ADIR gene exhibits conserved function and structure, with tissue-specific alternative splicing.
- Adir's association with the endoplasmic reticulum suggests a role in cellular homeostasis or stress response.