Bioengineered Vaults: Self-Assembling Protein Shell–Lipophilic Core Nanoparticles for Drug Delivery

Abstract

We report a novel approach to a new class of bioengineered, monodispersed, self-assembling vault nanoparticles consisting of a protein shell exterior with a lipophilic core interior designed for drug and probe delivery. Recombinant vaults were engineered to contain a small amphipathic α-helix derived from the nonstructural protein 5A of hepatitis C virus, thereby creating within the vault lumen a lipophilic microenvironment into which lipophilic compounds could be reversibly encapsulated. Multiple types of electron microscopy showed that attachment of this peptide resulted in larger than expected additional mass internalized within the vault lumen attributable to incorporation of host lipid membrane constituents spanning the vault waist (>35 nm). These bioengineered lipophilic vaults reversibly associate with a sample set of therapeutic compounds, including all-trans retinoic acid, amphotericin B, and bryostatin 1, incorporating hundreds to thousands of drug molecules per vault nanoparticle. Bryostatin 1 is of particular therapeutic interest because of its ability to potently induce expression of latent HIV, thus representing a preclinical lead in efforts to eradicate HIV/AIDS. Vaults loaded with bryostatin 1 released free drug, resulting in activation of HIV from provirus latency in vitro and induction of CD69 biomarker expression following intravenous injection into mice. The ability to preferentially and reversibly encapsulate lipophilic compounds into these novel bioengineered vault nanoparticles greatly advances their potential use as drug delivery systems.

Activation of the NLRP3 inflammasome by vault nanoparticles expressing a chlamydial epitope

“…Vault vaccines can also be engineered to induce specific adaptive immunity, as we have shown here that immunization of mice with PmpG-1-vaults induces generation of PmpG-1-responsive CD4 + cells immune cells. Vaults can also be engineered to deliver drugs and promote anti-tumor responses [26, 27, 29]. These studies define vault-vaccines as unique among other vaccines that induce NLRP3 inflammasomes, such as alum, as they are also able to induce specific marked T cell responses against antigens incorporated in the vault body.…”

Building Spatial Synthetic Biology with Compartments, Scaffolds, and Communities

“…For example, an amphipathic helix was fused to the amino terminus of the major vault protein, causing lipids to be encapsulated in the vault (Buehler et al 2014). The lipid-containing vaults bind with greater avidity to fat-soluble drugs.…”

Nanotechnology to augment immunotherapy for the treatment of glioblastoma multiforme

“…Vaults are ubiquitous ribonucleoprotein nanoparticles that are found naturally in eukaryotic organisms initially discovered by Rome and his colleagues at UCLA [70][71][72]. Because they are naturally present in the body, vaults are characterized by low toxicity.…”