In vivo siRNA delivery to the mouse hypothalamus confirms distinct roles of TR beta isoforms in regulating TRH transcription - siRNA

In vivo siRNA delivery to the mouse hypothalamus confirms distinct roles of TR beta isoforms in regulating TRH transcription
2006 Aug 21
Guissouma H, Froidevaux MS, Hassani Z, Demeneix BA.
Neurosci Lett.
RNA interference mediated by small interfering RNAs (siRNAs) is a powerful tool for evaluating gene function in vivo. In particular it should be able to provide tissue-specific and developmental stage-specific knock-down of target genes in physiological contexts. However, demonstrations of its use on neuronal specific genes in vivo are lacking. We examined whether a recently developed cationic lipid based approach was applicable to study the differential effects of the two beta thyroid hormone receptor (TR) isoforms, TRbeta1 and TRbeta2, on T(3)-transcriptional repression of the hypothalamic gene, TRH. The cationic lipid based technique used, JetSItrade mark/DOPE, was previously shown to efficiently knock-down reporter gene mRNA in vivo. Here we now show that its use to vectorise siRNA against TRbeta1 and TRbeta2 mRNA abrogates T(3)-mediated repression of hypothalamic TRH transcription. In particular, when using siRNA against either TRbeta1 or TRbeta2 differential effects are revealed. siRNA directed against TRbeta1 blocks both T(3) independent activation and T(3) dependent modulation of TRH transcription. In contrast, siRNA directed against TRbeta2 abrogates only T(3) repression of transcription. These results corroborate our previous findings obtained in mutant TRbeta(-/-) mice, showing that the TRbeta1 and TRbeta2 isoforms have differential effects on T(3)-TRH transcription. The data thus show that the cationic lipid-based siRNA strategy can effectively be used to reveal fine, tissue specific and isoform specific effects on neuronal gene transcription in vivo.
PMID: 16930836 [PubMed - as supplied by publisher]