Engineered zinc-finger proteins can compensate genetic haploinsufficiency by transcriptional activation of the wild-type allele: application to Willams-Beuren syndrome and supravalvular aortic stenosis.

Abstract

Williams-Beuren syndrome (WBS) and supravalvular aortic stenosis (SVAS) are genetic syndromes marked by the propensity to develop severe vascular stenoses. Vascular lesions in both syndromes are caused by haploinsufficiency of the elastin gene. We used these distinct genetic syndromes as models to evaluate the feasibility of using engineered zinc-finger protein transcription factors (ZFPs) to achieve compensatory expression of haploinsufficient genes by inducing augmented expression from the remaining wild-type allele. For complex genes with multiple splice variants, this approach could have distinct advantages over cDNA-based gene replacement strategies. Targeting the elastin gene, we show that transcriptional activation by engineered ZFPs can induce compensatory expression from the wild-type allele in the setting of classic WBS and SVAS genetic mutations, increase elastin expression in wild-type cells, induce expression of the major elastin splice variants, and recapitulate their natural stoichiometry. Further, we establish that transcriptional activation of the mutant allele in SVAS does not overcome nonsense-mediated decay, and thus ZFP-mediated transcriptional activation is not likely to induce production of a mutant protein, a crucial consideration. Finally, we show in bioengineered blood vessels that ZFP-mediated induction of elastin expression is capable of stimulating functional elastogenesis. Haploinsufficiency is a common mechanism of genetic disease. These findings have significant implications for WBS and SVAS, and establish that haploinsufficiency can be overcome by targeted transcriptional activation without inducing protein expression from the mutant allele.

• Authors: Pei Zhang, Angela Huang, Manuel Morales-Ruiz, Barry C Starcher, Yan Huang, William C Sessa, Laura E Niklason, Frank J Giordano
• Journal: Human gene therapy (Hum Gene Ther) Vol. 23 Issue 11 Pg. 1186-99 (Nov 2012) ISSN: 1557-7422 [Electronic] United States
• PMID: 22891920 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Elastin

Topics

• Alleles
• Aortic Stenosis, Supravalvular (genetics)
• Cell Line
• Cell Movement
• Cell Proliferation
• Dosage Compensation, Genetic
• Elastin (genetics, metabolism)
• Gene Expression
• Gene Expression Regulation
• Haploinsufficiency
• Humans
• Mutation
• Nonsense Mediated mRNA Decay
• Organ Specificity (genetics)
• Protein Engineering
• Transcriptional Activation
• Williams Syndrome (genetics)
• Zinc Fingers (genetics)