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Tissue-specific transgenic knockdown of Fos-related antigen 2 (Fra-2) expression mediated by dominant negative Fra-2
M Smith1, Z Burke, A Humphries
1School of Bioscience, Cardiff University, Cardiff, United Kingdom.
Abstract:
Fos-related antigen 2 (Fra-2) is a member of the Fos family of immediate-early genes, most of which are rapidly induced by second messengers. All members of this family act by binding to AP-1 sites as heterodimeric complexes with other proteins. However, each appears to have a distinct role. The role and biology of Fra-2 are less well understood than those of its relatives c-Fos, Fra-1, and FosB; moreover, Fra-2 target genes remain largely unknown, as does the basis of its selective effects on transcriptional activity. To pursue these issues, we created a transgenic rat line (NATDNF2) in which a dominant negative fra-2 (DNF2) gene is strongly expressed in the pineal gland; tissue selectivity was achieved by putting the DNF2 gene under the control of the rat arylalkylamine N-acetyltransferase (AANAT) regulatory region, which targets gene expression to a very restricted set of tissues (pineal gland >> retina). Expression of AANAT is normally turned on after the onset of darkness in the rat; as a result, pineal DNF2 expression occurs only at night. This was associated with marked suppression of the nocturnal increase in fra-2 mRNA and protein levels, indicating that DNF2 expression inhibits downstream effects of Fra-2, including the maintenance of high levels of fra-2 gene expression. Analysis of 1,190 genes in the NATDNF2 pineal gland, including the AANAT gene, identified two whose expression is strongly linked to fra-2 expression: the genes encoding type II iodothyronine deiodinase and nectadrin (CD24).
Insights
Researchers created a transgenic rat model to study Fos-related antigen 2 (Fra-2) in the pineal gland. This model revealed Fra-2
Area of Science:
- Molecular Biology
- Genetics
- Neuroendocrinology
Background:
- Fos-related antigen 2 (Fra-2) is a Fos family immediate-early gene with poorly understood roles and target genes.
- Understanding Fra-2's specific functions and transcriptional regulation is crucial for deciphering its biological significance.
- Existing knowledge on Fra-2 is limited compared to related Fos family members like c-Fos, Fra-1, and FosB.
Purpose of the Study:
- To investigate the biological role and target genes of Fos-related antigen 2 (Fra-2) in vivo.
- To establish a transgenic rat model for studying Fra-2 function in a tissue-specific manner.
- To identify genes regulated by Fra-2 in the pineal gland.
Main Methods:
- Creation of a transgenic rat line (NATDNF2) expressing a dominant-negative Fra-2 (DNF2) specifically in the pineal gland.
- Utilized the arylalkylamine N-acetyltransferase (AANAT) promoter for tissue-specific and nocturnal gene expression targeting.
- Analyzed gene expression changes in the NATDNF2 rat pineal gland using a comprehensive gene array (1,190 genes).
Main Results:
- The DNF2 transgene was expressed nocturnally in the pineal gland, mirroring normal AANAT expression patterns.
- Pineal DNF2 expression significantly suppressed the nocturnal induction of endogenous fra-2 mRNA and protein.
- Gene expression analysis identified type II iodothyronine deiodinase and nectadrin (CD24) as two genes strongly linked to fra-2 expression.
Conclusions:
- The developed transgenic rat model effectively inhibits Fra-2 activity in the pineal gland.
- Fra-2 plays a role in maintaining its own gene expression and influences the expression of specific downstream genes.
- Type II iodothyronine deiodinase and nectadrin are identified as potential Fra-2 target genes in the pineal gland.