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Bone- and muscle-targeted adeno-associated viral vectors enable tissue-selective vitamin D receptor knockdown in mice

delete2026-07-29
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OA
AI
A
Alexandra K O’Donohue *
J
Julian Chu
N
Nicholas Norris
H
Hsien-Yin Kao
J
Josephine Yu
L
Lucinda R. Lee
D
Dirk Grimm
J
Jenny E. Gunton
A
Aaron Schindeler
DOI:10.1038/s41434-026-00636-ydelete
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Abstract

Abstract

En 中文
Vitamin D receptor (VDR) regulates musculoskeletal biology, but its adult, tissue-specific roles are difficult to resolve with germline or conventional conditional knockouts. We developed recombinant adeno-associated viral vectors (rAAVs) to drive Cre recombinase selectively in bone or muscle and used them to delete Vdr postnatally in Vdrfl/fl mice. To engineer a muscle-selective vector, we screened AAV9 constructs carrying candidate muscle promoters and identified tMCKΔ63 as the most selective promoter. Packaging this cassette in the myotropic AAVMYO capsid further reduced off-target skeletal expression while preserving strong muscle transduction. Local intramuscular delivery of AAVMYO–tMCKΔ63 enabled unilateral targeting with minimal systemic spread. In parallel, a bone-selective AAV8-Sp7 vector supported skeletal delivery. These vectors produced tissue-restricted Vdr deletion in VdrmuscleAAV and VdrboneAAV mice. Muscle-targeted VDR loss reduced grip strength (–9.27%, p < 0.01) and endurance (–16.58%, p < 0.05). Bone-targeted deletion caused modest but significant skeletal changes, including increased cortical thickness ( + 7%, p < 0.05) and higher vertebral stiffness ( + 27%, p < 0.001), without effects on body weight or tibial strength. This scalable, crossbreeding-independent strategy enables compartment-specific functional studies in floxed models, including genes with embryonic lethality or complex tissue interactions. It also provides a general framework for iterative capsid-promoter optimization to maximize specificity in vivo across diverse tissues.

Journal

Gene Therapy cover
Gene Therapy
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bioengineering and molecular medicine laboratory
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Faculty of Engineering Sciences
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