Dual-isoform hUBE3A gene transfer improves behavioral and seizure outcomes in Angelman syndrome model mice
Matthew C. Judson, Charles Shyng, Jeremy M. Simon, Courtney R. Davis, A. Mattijs Punt, Mirabel T. Salmon, Noah W. Miller, Kimberly D. Ritola, Ype Elgersma, David G. Amaral, Steven J. Gray, Benjamin D. Philpot
Matthew C. Judson, Charles Shyng, Jeremy M. Simon, Courtney R. Davis, A. Mattijs Punt, Mirabel T. Salmon, Noah W. Miller, Kimberly D. Ritola, Ype Elgersma, David G. Amaral, Steven J. Gray, Benjamin D. Philpot
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Research Article Neuroscience Therapeutics

Dual-isoform hUBE3A gene transfer improves behavioral and seizure outcomes in Angelman syndrome model mice

Abstract

Loss of the maternal UBE3A allele causes Angelman syndrome (AS), a debilitating neurodevelopmental disorder. Here, we devised an AS treatment strategy based on reinstating dual-isoform expression of human UBE3A (hUBE3A) in the developing brain. Kozak sequence engineering of our codon-optimized vector (hUBE3Aopt) enabled translation of both short and long hUBE3A protein isoforms at a near-endogenous 3:1 (short/long) ratio, a feature that could help to support optimal therapeutic outcomes. To model widespread brain delivery and early postnatal onset of hUBE3A expression, we packaged the hUBE3Aopt vector into PHP.B capsids and performed intracerebroventricular injections in neonates. This treatment significantly improved motor learning and innate behaviors in AS mice, and it rendered them resilient to epileptogenesis and associated hippocampal neuropathologies induced by seizure kindling. hUBE3A overexpression occurred frequently in the hippocampus but was uncommon in the neocortex and other major brain structures; furthermore, it did not correlate with behavioral performance. Our results demonstrate the feasibility, tolerability, and therapeutic potential for dual-isoform hUBE3A gene transfer in the treatment of AS.

Authors

Matthew C. Judson, Charles Shyng, Jeremy M. Simon, Courtney R. Davis, A. Mattijs Punt, Mirabel T. Salmon, Noah W. Miller, Kimberly D. Ritola, Ype Elgersma, David G. Amaral, Steven J. Gray, Benjamin D. Philpot

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Figure 1

UBE3A isoform expression in mouse and human brain.

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UBE3A isoform expression in mouse and human brain. (A) N-terminal amino...
(A) N-terminal amino acid sequences of human and mouse UBE3A isoforms. Highly conserved sequences beginning the short isoform are shown in burgundy; N-terminal amino acid extensions characteristic of long UBE3A isoforms are shown in blue or green. (B) Box plots of mUbe3a isoform expression in mouse brain regions across development. Whiskers represent 1.5 × interquartile range (IQR). Isoform fraction was calculated from RNA-seq coverage over exons common to all mUbe3a transcripts (exon 4) or specific to long mUbe3a (exon 3). The long mUbe3a (isoform 2) fraction was computed as Exon 3/Exon 4; the short mUbe3a (isoform 3) fraction was computed as (Exon 4 – Exon 3)/Exon 4. (C) Box plots of hUBE3A isoform expression in human brain regions across development and aging. Whiskers represent 1.5 × IQR. Isoform fractions were estimated from RNA-seq coverage over hUBE3A exons including exon 6, which is common to all hUBE3A transcripts, and exons 3 and 4, which encode long hUBE3A isoforms 3 and 2, respectively, when spliced to exon 6. Exon 3 and 4 reads were weighted according to exon 6 splicing frequencies previously published for human cortex (33). Long hUBE3A isoform 3 was computed as (0.322 × Exon 3)/Exon 6; long hUBE3A isoform 2 was computed as (0.071 × Exon 4)/Exon 6; short hUBE3A isoform 1 was computed as (Exon 6 – [(0.322 × Exon 3) + (0.071 × Exon 4)])/Exon 6.