Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
449
result(s) for
"Corey, David P."
Sort by:
High levels of AAV vector integration into CRISPR-induced DNA breaks
Adeno-associated virus (AAV) vectors have shown promising results in preclinical models, but the genomic consequences of transduction with AAV vectors encoding CRISPR-Cas nucleases is still being examined. In this study, we observe high levels of AAV integration (up to 47%) into Cas9-induced double-strand breaks (DSBs) in therapeutically relevant genes in cultured murine neurons, mouse brain, muscle and cochlea. Genome-wide AAV mapping in mouse brain shows no overall increase of AAV integration except at the CRISPR/Cas9 target site. To allow detailed characterization of integration events we engineer a miniature AAV encoding a 465 bp lambda bacteriophage DNA (AAV-λ465), enabling sequencing of the entire integrated vector genome. The integration profile of AAV-465λ in cultured cells display both full-length and fragmented AAV genomes at Cas9 on-target sites. Our data indicate that AAV integration should be recognized as a common outcome for applications that utilize AAV for genome editing.
In-depth characterization of adeno-associated virus (AAV)-mediated CRISPR delivery is still lacking. Here, the authors show high levels of integration into Cas9-induced double-strand breaks (DSBs) in therapeutically relevant genes in vivo.
Journal Article
Structure of a force-conveying cadherin bond essential for inner-ear mechanotransduction
A combination of structural, computational and biophysical tools is used to characterize the bond between tip-link proteins protocadherin 15 and cadherin 23, which have an essential role in inner-ear mechanotransduction; the bond, involving an extended protein handshake, is found to be affected by deafness mutations and is mechanically strong enough to resist forces in hair cells, adding to our understanding of hair-cell sensory transduction and interactions among cadherins.
Mechanism of hair-cell sensory transduction
Hair cells in the inner ear transform mechanical stimuli into electrical signals that are crucial for hearing and balance. These cells contain actin-rich stereocilia that are interconnected by filaments such as the tip link, which forms the mechanotransduction apparatus. The adhesion molecules protocadherin 15 and cadherin 23 form the tip link. In this study, David Corey
et al
. use a combination of structural and biophysical experiments to characterize the bond between cadherin 23 and protocadherin 15. The bond is mechanically strong enough to resist forces in hair cells and requires calcium to maintain stability. These results provide molecular insights into the mechanics of hair-cell sensory transduction.
Hearing and balance use hair cells in the inner ear to transform mechanical stimuli into electrical signals
1
. Mechanical force from sound waves or head movements is conveyed to hair-cell transduction channels by tip links
2
,
3
, fine filaments formed by two atypical cadherins known as protocadherin 15 and cadherin 23 (refs
4
,
5
). These two proteins are involved in inherited deafness
6
,
7
,
8
,
9
,
10
and feature long extracellular domains that interact tip-to-tip
5
,
11
in a Ca
2+
-dependent manner. However, the molecular architecture of this complex is unknown. Here we combine crystallography, molecular dynamics simulations and binding experiments to characterize the protocadherin 15–cadherin 23 bond. We find a unique cadherin interaction mechanism, in which the two most amino-terminal cadherin repeats (extracellular cadherin repeats 1 and 2) of each protein interact to form an overlapped, antiparallel heterodimer. Simulations predict that this tip-link bond is mechanically strong enough to resist forces in hair cells. In addition, the complex is shown to become unstable in response to Ca
2+
removal owing to increased flexure of Ca
2+
-free cadherin repeats. Finally, we use structures and biochemical measurements to study the molecular mechanisms by which deafness mutations disrupt tip-link function. Overall, our results shed light on the molecular mechanics of hair-cell sensory transduction and on new interaction mechanisms for cadherins, a large protein family implicated in tissue and organ morphogenesis
12
,
13
, neural connectivity
14
and cancer
15
.
Journal Article
The Outer Pore and Selectivity Filter of TRPA1
TRPA1 (transient-receptor-potential-related ion channel with ankyrin domains) is a direct receptor or indirect effector for a wide variety of nociceptive signals, and thus is a compelling target for development of analgesic pharmaceuticals such as channel blockers. Recently, the structure of TRPA1 was reported, providing insights into channel assembly and pore architecture. Here we report whole-cell and single-channel current recordings of wild-type human TRPA1 as well as TRPA1 bearing point mutations of key charged residues in the outer pore. These measurements demonstrate that the glutamate at position 920 plays an important role in collecting cations into the mouth of the pore, by changing the effective surface potential by ~16 mV, while acidic residues further out have little effect on permeation. Electrophysiology experiments also confirm that the aspartate residue at position 915 represents a constriction site of the TRPA1 pore and is critical in controlling ion permeation.
Journal Article
Mini-PCDH15 gene therapy rescues hearing in a mouse model of Usher syndrome type 1F
Usher syndrome type 1 F (USH1F), caused by mutations in the protocadherin-15 gene (
PCDH15
), is characterized by congenital deafness, lack of balance, and progressive blindness. In hair cells, the receptor cells of the inner ear, PCDH15 is a component of tip links, fine filaments which pull open mechanosensory transduction channels. A simple gene addition therapy for USH1F is challenging because the PCDH15 coding sequence is too large for adeno-associated virus (AAV) vectors. We use rational, structure-based design to engineer mini-PCDH15s in which 3–5 of the 11 extracellular cadherin repeats are deleted, but which still bind a partner protein. Some mini-PCDH15s can fit in an AAV. An AAV encoding one of these, injected into the inner ears of mouse models of USH1F, produces a mini-PCDH15 which properly forms tip links, prevents the degeneration of hair cell bundles, and rescues hearing. Mini-PCDH15s may be a useful therapy for the deafness of USH1F.
Mutations in PCDH15 cause deafness and blindness in Usher syndrome 1 F, but gene therapy is difficult because the PCDH15 sequence is too large for AAV vectors. Here, the authors engineered a miniPCDH15 that fits in AAV and rescues hearing in mouse Usher syndrome 1F models.
Journal Article
Rescue of Hearing by Gene Delivery to Inner-Ear Hair Cells Using Exosome-Associated AAV
Adeno-associated virus (AAV) is a safe and effective vector for gene therapy for retinal disorders. Gene therapy for hearing disorders is not as advanced, in part because gene delivery to sensory hair cells of the inner ear is inefficient. Although AAV transduces the inner hair cells of the mouse cochlea, outer hair cells remain refractory to transduction. Here, we demonstrate that a vector, exosome-associated AAV (exo-AAV), is a potent carrier of transgenes to all inner ear hair cells. Exo-AAV1-GFP is more efficient than conventional AAV1-GFP, both in mouse cochlear explants in vitro and with direct cochlear injection in vivo. Exo-AAV shows no toxicity in vivo, as assayed by tests of auditory and vestibular function. Finally, exo-AAV1 gene therapy partially rescues hearing in a mouse model of hereditary deafness (lipoma HMGIC fusion partner-like 5/tetraspan membrane protein of hair cell stereocilia [Lhfpl5/Tmhs−/−]). Exo-AAV is a powerful gene delivery system for hair cell research and may be useful for gene therapy for deafness.
[Display omitted]
Gene therapy for deafness is difficult because few vectors transduce inner ear sensory cells, and those that do, transduce only one type. In a mouse model, György and colleagues demonstrate that exosome-associated AAV vectors efficiently deliver genes to all inner ear sensory cells and rescue hearing in deaf mice.
Journal Article
PKHD1L1 is a coat protein of hair-cell stereocilia and is required for normal hearing
The bundle of stereocilia on inner ear hair cells responds to subnanometer deflections produced by sound or head movement. Stereocilia are interconnected by a variety of links and also carry an electron-dense surface coat. The coat may contribute to stereocilia adhesion or protect from stereocilia fusion, but its molecular identity remains unknown. From a database of hair-cell-enriched translated proteins, we identify Polycystic Kidney and Hepatic Disease 1-Like 1 (PKHD1L1), a large, mostly extracellular protein of 4249 amino acids with a single transmembrane domain. Using serial immunogold scanning electron microscopy, we show that PKHD1L1 is expressed at the tips of stereocilia, especially in the high-frequency regions of the cochlea. PKHD1L1-deficient mice lack the surface coat at the upper but not lower regions of stereocilia, and they develop progressive hearing loss. We conclude that PKHD1L1 is a component of the surface coat and is required for normal hearing in mice.
There is little known about the function or molecular identity of the electron-dense stereocilia coat, which is transiently present at the surface of stereocilia. In this study authors screened a database of hair-cell-enriched translated proteins to identify the expression of Polycystic Kidney and Hepatic Disease 1-Like 1 (PKHD1L1), a large, mostly extracellular protein, and show that it forms the coat at the tips of stereocilia and is required for normal hearing in mice
Journal Article
Single-molecule force spectroscopy reveals the dynamic strength of the hair-cell tip-link connection
The conversion of auditory and vestibular stimuli into electrical signals is initiated by force transmitted to a mechanotransduction channel through the tip link, a double stranded protein filament held together by two adhesion bonds in the middle. Although thought to form a relatively static structure, the dynamics of the tip-link connection has not been measured. Here, we biophysically characterize the strength of the tip-link connection at single-molecule resolution. We show that a single tip-link bond is more mechanically stable relative to classic cadherins, and our data indicate that the double stranded tip-link connection is stabilized by single strand rebinding facilitated by strong cis-dimerization domains. The measured lifetime of seconds suggests the tip-link is far more dynamic than previously thought. We also show how Ca
2+
alters tip-link lifetime through elastic modulation and reveal the mechanical phenotype of a hereditary deafness mutation. Together, these data show how the tip link is likely to function during mechanical stimuli.
The conversion of auditory and vestibular stimuli into electrical signals is initiated by force transmitted to a mechanotransduction channel through the tip link. Here authors show that a single tip-link bond is more mechanically stable relative to classic cadherins, and that the double stranded tip-link connection is stabilized by single strand rebinding facilitated by strong cis-dimerization domains.
Journal Article
PCDH15 dual-AAV gene therapy for deafness and blindness in Usher syndrome type 1F models
Usher syndrome type 1F (USH1F), resulting from mutations in the protocadherin-15 (PCDH15) gene, is characterized by congenital lack of hearing and balance, and progressive blindness in the form of retinitis pigmentosa. In this study, we explore an approach for USH1F gene therapy, exceeding the single AAV packaging limit by employing a dual-adeno-associated virus (dual-AAV) strategy to deliver the full-length PCDH15 coding sequence. We demonstrate the efficacy of this strategy in mouse USH1F models, effectively restoring hearing and balance in these mice. Importantly, our approach also proves successful in expressing PCDH15 protein in clinically relevant retinal models, including human retinal organoids and nonhuman primate retina, showing efficient targeting of photoreceptors and proper protein expression in the calyceal processes. This research represents a major step toward advancing gene therapy for USH1F and the multiple challenges of hearing, balance, and vision impairment.
Journal Article
Length regulation of mechanosensitive stereocilia depends on very slow actin dynamics and filament-severing proteins
Auditory sensory hair cells depend on stereocilia with precisely regulated lengths to detect sound. Since stereocilia are primarily composed of crosslinked, parallel actin filaments, regulated actin dynamics are essential for controlling stereocilia length. Here we assessed stereocilia actin turnover by monitoring incorporation of inducibly expressed β-actin-GFP in adult mouse hair cells
in vivo
and by directly measuring β-actin-GFP turnover in explants. Stereocilia actin incorporation is remarkably slow and restricted to filament barbed ends in a small tip compartment, with minimal accumulation in the rest of the actin core. Shorter rows of stereocilia, which have mechanically gated ion channels, show more variable actin turnover than the tallest stereocilia, which lack channels. Finally, the proteins ADF and AIP1, which both mediate actin filament severing, contribute to stereocilia length maintenance. Altogether, the data support a model whereby stereocilia actin cores are largely static, with dynamic regulation at the tips to maintain a critical length.
Auditory sensory hair cells detect sounds by deflection of their actin-based stereocilia, which vary in length. By inducing expression of GFP-actin in mouse hair cells
in vivo
, Narayanan
et al
. demonstrate that stereocilia length is regulated by very slow actin turnover, which is restricted to the tips.
Journal Article