Dual-reporter assay for selective small molecule inhibition of expanded toxic huntingtin

A dual-reporter bacterial assay co-expressing exon 1 HTT and mHTT fused to spectrally distinct fluorescent proteins enables simultaneous measurement of allele-selective huntingtin expression changes.

• Why it matters: Huntington’s disease depends on CAG repeat expansion, and therapies must downregulate mutant huntingtin while preserving wildtype huntingtin; existing screens often can’t assess both efficacy and allele selectivity together.
• What they did: The authors built a high-throughput bacterial platform with dual fluorescent reporters and validated it using two CAG repeat binding compounds, then used circular dichroism spectroscopy and cell-free protein synthesis to probe mechanisms.
• The result: Furamidine showed reproducible, sequence-dependent effects that altered HTT RNA stability and selectively decreased wildtype Htt expression, while myricetin’s apparent decrease was linked to fluorophore artifacts, supporting the assay for screening allele-selective modulators.

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