Atrial-Specific Gene Delivery Using an Adeno-Associated Viral Vector

Circ Res. 2019 Jan 18;124(2):256-262. doi: 10.1161/CIRCRESAHA.118.313811.

Abstract

Rationale: Somatic overexpression in mice using an adeno-associated virus (AAV) as gene transfer vectors has become a valuable tool to analyze the roles of specific genes in cardiac diseases. The lack of atrial-specific AAV vector has been a major obstacle for studies into the pathogenesis of atrial diseases. Moreover, gene therapy studies for atrial fibrillation would benefit from atrial-specific vectors. Atrial natriuretic factor (ANF) promoter drives gene expression specifically in atrial cardiomyocytes.

Objective: To establish the platform of atrial specific in vivo gene delivery by AAV-ANF.

Methods and results: We constructed AAV vectors based on serotype 9 (AAV9) that are driven by the atrial-specific ANF promoter. Hearts from mice injected with AAV9-ANF-GFP (green fluorescent protein) exhibited strong and atrial-specific GFP expression without notable GFP in ventricular tissue. In contrast, similar vectors containing a cardiac troponin T promoter (AAV9-TNT4-GFP) showed GFP expression in all 4 chambers of the heart, while AAV9 with an enhanced chicken β-actin promoter (AAV-enCB-GFP) caused ubiquitous GFP expression. Next, we used Rosa26mT/mG (membrane-targeted tandem dimer Tomato/membrane-targeted GFP), a double-fluorescent Cre reporter mouse that expresses membrane-targeted tandem dimer Tomato before Cre-mediated excision, and membrane-targeted GFP after excision. AAV9-ANF-Cre led to highly efficient LoxP recombination in membrane-targeted tandem dimer Tomato/membrane-targeted green fluorescent protein mice with high specificity for the atria. We measured the frequency of transduced cardiomyocytes in atria by detecting Cre-dependent GFP expression from the Rosa26mT/mG allele. AAV9 dose was positively correlated with the number of GFP-positive atrial cardiomyocytes. Finally, we assessed whether the AAV9-ANF-Cre vector could be used to induce atrial-specific gene knockdown in proof-of-principle experiments using conditional JPH2 (junctophilin-2) knockdown mice. Four weeks after AAV9-ANF-Cre injection, a strong reduction in atrial expression of JPH2 protein was observed. Furthermore, there was evidence for abnormal Ca2+ handling in atrial myocytes isolated from mice with atrial-restricted JPH2 deficiency.

Conclusions: AAV9-ANF vectors produce efficient, dose-dependent, and atrial-specific gene expression following a single-dose systemic delivery in mice. This vector is a novel reagent for both mechanistic and gene therapy studies on atrial diseases.

Keywords: animals; atrial fibrillation; atrial natriuretic factor; gene therapy; mice.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atrial Natriuretic Factor
  • Calcium Signaling
  • Dependovirus / genetics*
  • Dependovirus / metabolism
  • Disease Models, Animal
  • Down-Regulation
  • Female
  • Gene Knock-In Techniques*
  • Gene Knockdown Techniques*
  • Gene Transfer Techniques*
  • Genes, Reporter
  • Genetic Vectors*
  • Heart Atria / metabolism*
  • Heart Atria / pathology
  • Heart Atria / physiopathology
  • Heart Failure / genetics
  • Heart Failure / metabolism
  • Heart Failure / pathology
  • Heart Failure / physiopathology
  • Luminescent Proteins / biosynthesis
  • Luminescent Proteins / genetics
  • Male
  • Membrane Proteins / deficiency
  • Membrane Proteins / genetics
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Muscle Proteins / deficiency
  • Muscle Proteins / genetics
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • Natriuretic Peptide, C-Type / genetics*
  • Promoter Regions, Genetic
  • Protein Precursors / genetics*
  • Up-Regulation

Substances

  • Luminescent Proteins
  • Membrane Proteins
  • Muscle Proteins
  • Nppa protein, mouse
  • Protein Precursors
  • junctophilin-2 protein, mouse
  • Natriuretic Peptide, C-Type
  • Atrial Natriuretic Factor