Expression of a PCSK9 Gain-of-Function Mutation in C57BL/6J Mice to Facilitate Angiotensin II-Induced AAAs

Abstract

Angiotensin II (AngII) infusion in mice has been used widely to investigate mechanisms of abdominal aortic aneurysms (AAAs). To achieve a high incidence of AngII-induced AAAs, mice should be hypercholesterolemic. Therefore, either low-density lipoprotein receptor (LDLR) or apolipoprotein E deficiency have been used as a hypercholesterolemic background. However, it is a time-consuming and expensive process to generate compound deficient strains that have either an LDLR or apolipoprotein E deficient background. Proprotein convertase subtilisin/kexin type 9 (PCSK9) facilitates the degradation of LDL receptors. Previous studies demonstrated profound increases of plasma cholesterol concentrations after a single intraperitoneal injection of adeno-associated viruses (AAV) expressing a gain-of-function mutation of mouse PCSK9 (AAV.mPCSK9D377Y) in C57BL/6J mice fed a Western diet. Of note, injection of AAV.mPCSK9D377Y augmented AngII-induced AAA formation in C57BL/6J mice that had comparable severity of AAAs to LDLR deficient mice. Thus, AAV.mPCSK9D377Y infection greatly expedites studies on a gene of interest using AngII-induced AAAs. This commentary provides a brief technical guide of this approach and discusses the pros and cons of its use in AAA research.

Early Progression of Abdominal Aortic Aneurysm is Decelerated by Improved Endothelial Barrier Function via ALDH2‐LIN28B‐ELK3 Signaling

“…The mice were administered an adeno‐associated virus (AAV8) vector to overexpress Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9 D377Y ), a gain‐of‐function mutation. The mice were then exposed to a high‐fat diet and subjected to Ang II infusion to induce AAA [ 33 ] (Figure 2H). ECs‐specific ALDH2 knockout did not alter the aortic diameter and histological morphology prior to Ang II treatment (Figure S3, Supporting Information), and did not change metabolic parameters 4 weeks after Ang II challenge (Figure S4A–E, Supporting Information).…”

“…The PCSK9/Ang II‐induced murine AAA model was generated as previously described. [ 33 ] In brief, 8–10 weeks male mice were administered via the lateral tail intravenous (IV) injections of 2 × 10 11 genomic copies of adeno‐associated virus (AAV, serotype 8) carrying a gain‐of‐function mutation of the mouse Pcsk9 (AAV.Mpcsk9 D377Y ) and food was changed to a western diet (HCD, 17.3% protein, 21.2% fat, 48.5% carbohydrate, 0.2% cholesterol by mass, and 42% calories from fat; TD.88137, Envigo) immediately after injection. Two weeks after AAVs injection, Osmotic pumps (Durect, Alzet 2004) containing Angiotensin II (Ang II) (1000 ng kg −1 min −1 , Sigma, 05‐23‐0101) were implanted and western diet was continued for 4 weeks to induce AAA formation.…”

Aortic Aneurysm and Dissection: Heterogeneity and Molecular Mechanisms

“…Of note, adeno-associated viruses (AAVs) containing a gain-of-function mutation of PCSK9 can induce hypercholesterolemia in C57BL/6 mice within a week [ 5 , 6 , 7 ]. In a commentary of this Special Issue, Sawada and colleagues described the detailed method of how to use AAVs containing a mouse PCSK9 gain-of-function mutation [ 8 ]. In an original research article of this Special Issue, Ikezoe et al [ 9 ] provided solid data that hypercholesterolemia by this PCSK9 AAV induction does not augment elastase-induced AAAs in mice, implicating potentially different mechanisms between AngII and elastase-induced AAAs.…”