Presentation Title

Huntington's Disease: Therapeutic strategy to reduce mutant huntingtin protein

Faculty Mentor

Baljit S. Khakh

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

100

Session

poster 4

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Astrocytes are an essential component of neural circuits, and recent evidence suggests that they contribute to the development of multiple brain disorders. HD is an autosomal dominant neurodegenerative disorder caused by mutations in the Htt gene that lead to the formation of mutant huntingtin (mHtt) with expanded CAG repeats. In the quest to develop therapeutic treatments for HD, major effort is being directed at lowering the levels of mHtt. To understand the effects of mHtt reduction in mice, we designed a strategy based on zinc-finger protein transcription factor (ZFP-TF) repressors currently being developed by Sangamo/Shire to specifically target mHtt. We cloned ZFP-TF constructs to be expressed under neuron specific promoter hSyn1 and generated AAVs to test them in mice. We found hSyn1-ZFP-TF expressed selectively in over 80% of striatal neurons with negligible expression in astrocytes. We then tested hSyn1-ZFP-TF in the R6/2 mouse model of HD. Briefly, the AAVs were injected in 4 w old mice striatum bilaterally and HD-specific behavior assessed at 10 w of age. Astrocytes and neurons contain mHtt puncta in the nucleus. However, what happens to mHtt load in astrocytes and neurons as the disease progresses is not known. To address this question, we also performed immunohistochemistry in 2 different HD mouse models at three different disease states. We will report these data as well as astrocyte-specific and neuron-specific gene expression changes using RNAseq in R6/2 mice injected with ZFP30645 (functional) or ZFPDeltaDBD (control). Our data should reveal reversible molecular signatures for striatal astrocytes and neurons following mHtt lowering in vivo.

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Huntington's Disease: Therapeutic strategy to reduce mutant huntingtin protein

100

Astrocytes are an essential component of neural circuits, and recent evidence suggests that they contribute to the development of multiple brain disorders. HD is an autosomal dominant neurodegenerative disorder caused by mutations in the Htt gene that lead to the formation of mutant huntingtin (mHtt) with expanded CAG repeats. In the quest to develop therapeutic treatments for HD, major effort is being directed at lowering the levels of mHtt. To understand the effects of mHtt reduction in mice, we designed a strategy based on zinc-finger protein transcription factor (ZFP-TF) repressors currently being developed by Sangamo/Shire to specifically target mHtt. We cloned ZFP-TF constructs to be expressed under neuron specific promoter hSyn1 and generated AAVs to test them in mice. We found hSyn1-ZFP-TF expressed selectively in over 80% of striatal neurons with negligible expression in astrocytes. We then tested hSyn1-ZFP-TF in the R6/2 mouse model of HD. Briefly, the AAVs were injected in 4 w old mice striatum bilaterally and HD-specific behavior assessed at 10 w of age. Astrocytes and neurons contain mHtt puncta in the nucleus. However, what happens to mHtt load in astrocytes and neurons as the disease progresses is not known. To address this question, we also performed immunohistochemistry in 2 different HD mouse models at three different disease states. We will report these data as well as astrocyte-specific and neuron-specific gene expression changes using RNAseq in R6/2 mice injected with ZFP30645 (functional) or ZFPDeltaDBD (control). Our data should reveal reversible molecular signatures for striatal astrocytes and neurons following mHtt lowering in vivo.