Retinal gene therapy with adeno-associated viral (AAV) vectors holds promises for treating inherited and noninherited diseases of the eye. Although clinical data suggest that retinal gene therapy is ...safe and effective, delivery of large genes is hindered by the limited AAV cargo capacity. Protein trans-splicing mediated by split inteins is used by single-cell organisms to reconstitute proteins. Here, we show that delivery of multiple AAV vectors each encoding one of the fragments of target proteins flanked by short split inteins results in protein trans-splicing and full-length protein reconstitution in the retina of mice and pigs and in human retinal organoids. The reconstitution of large therapeutic proteins using this approach improved the phenotype of two mouse models of inherited retinal diseases. Our data support the use of split intein-mediated protein trans-splicing in combination with AAV subretinal delivery for gene therapy of inherited blindness due to mutations in large genes.
Diagnosis and cure for rare diseases represent a great challenge for the scientific community who often comes up against the complexity and heterogeneity of clinical picture associated to a high cost ...and time-consuming drug development processes. Here we show a drug repurposing strategy applied to nephropathic cystinosis, a rare inherited disorder belonging to the lysosomal storage diseases. This approach consists in combining mechanism-based and cell-based screenings, coupled with an affordable computational analysis, which could result very useful to predict therapeutic responses at both molecular and system levels. Then, we identified potential drugs and metabolic pathways relevant for the pathophysiology of nephropathic cystinosis by comparing gene-expression signature of drugs that share common mechanisms of action or that involve similar pathways with the disease gene-expression signature achieved with RNA-seq.
High-throughput clustered regularly interspaced short palindromic repeats (CRISPR) screens identified pro- and antiviral host factors.SARS-CoV-2 subverts the membrane trafficking system at multiple ...levels.The virus recruits host proteins to modulate membrane remodeling for replication, virus particle formation, and propagation.Different SARS-CoV-2 egress routes have been proposed.
The molecular mechanisms underlying SARS-CoV-2 host cell invasion and life cycle have been studied extensively in recent years, with a primary focus on viral entry and internalization with the aim of identifying antiviral therapies. By contrast, our understanding of the molecular mechanisms involved in the later steps of the coronavirus life cycle is relatively limited. In this review, we describe what is known about the host factors and viral proteins involved in the replication, assembly, and egress phases of SARS-CoV-2, which induce significant host membrane rearrangements. We also discuss the limits of the current approaches and the knowledge gaps still to be addressed.
The molecular mechanisms underlying SARS-CoV-2 host cell invasion and life cycle have been studied extensively in recent years, with a primary focus on viral entry and internalization with the aim of identifying antiviral therapies. By contrast, our understanding of the molecular mechanisms involved in the later steps of the coronavirus life cycle is relatively limited. In this review, we describe what is known about the host factors and viral proteins involved in the replication, assembly, and egress phases of SARS-CoV-2, which induce significant host membrane rearrangements. We also discuss the limits of the current approaches and the knowledge gaps still to be addressed.
SARS-CoV-2, like other coronaviruses, builds a membrane-bound replication organelle (RO) to enable RNA replication
. The SARS-CoV-2 RO is composed of double membrane vesicles (DMVs) tethered to the ...endoplasmic reticulum (ER) by thin membrane connectors
, but the viral proteins and the host factors involved are currently unknown. Here we identify the viral non-structural proteins (NSPs) that generate the SARS-CoV-2 RO. NSP3 and NSP4 generate the DMVs while NSP6, through oligomerization and an amphipathic helix, zippers ER membranes and establishes the connectors. The NSP6ΔSGF mutant, which arose independently in the α, β, γ, η, ι, and λ variants of SARS-CoV-2, behaves as a gain-of-function mutant with a higher ER-zippering activity. We identified three main roles for NSP6: to act as a filter in RO-ER communication allowing lipid flow but restricting access of ER luminal proteins to the DMVs, to position and organize DMV clusters, and to mediate contact with lipid droplets (LDs) via the LD-tethering complex DFCP1-Rab18. NSP6 thus acts as an organizer of DMV clusters and can provide a selective track to refurbish them with LD-derived lipids. Importantly, both properly formed NSP6 connectors and LDs are required for SARS-CoV-2 replication. Our findings, uncovering the biological activity of NSP6 of SARS-CoV-2 and of other coronaviruses, have the potential to fuel the search for broad antiviral agents.
The TRAnsport Protein Particle (TRAPP) complex controls multiple membrane trafficking steps and is strategically positioned to mediate cell adaptation to diverse environmental conditions, including ...acute stress. We have identified the TRAPP complex as a component of a branch of the integrated stress response that impinges on the early secretory pathway. The TRAPP complex associates with and drives the recruitment of the COPII coat to stress granules (SGs) leading to vesiculation of the Golgi complex and arrest of ER export. The relocation of the TRAPP complex and COPII to SGs only occurs in cycling cells and is CDK1/2‐dependent, being driven by the interaction of TRAPP with hnRNPK, a CDK substrate that associates with SGs when phosphorylated. In addition, CDK1/2 inhibition impairs TRAPP complex/COPII relocation to SGs while stabilizing them at ER exit sites. Importantly, the TRAPP complex controls the maturation of SGs. SGs that assemble in TRAPP‐depleted cells are smaller and are no longer able to recruit RACK1 and Raptor, two TRAPP‐interactive signaling proteins, sensitizing cells to stress‐induced apoptosis.
Synopsis
The TRAnsport Protein Particle (TRAPP) complex, which controls multiple membrane trafficking steps along the secretory pathway, mediates cellular adaptation to acute stress by associating with and driving the recruitment of the COPII coat to stress granules (SGs), thereby halting secretion and possibly limiting energy consumption.
The TRAPP complex associates with and drives the recruitment of the COPII coat to SGs.
The TRAPP complex promotes the maturation of SGs.
Relocation of TRAPP complex and COPII to SGs depends on CDK1/2 and occurs only in cycling cells.
Association of TRAPP complex and COPII with SGs halts secretion.
TRAPP‐dependent stress granule recruitment of COPII vesicle coats to halt secretion and limit energy consumption is involved in cellular adapation to acute stress.
Cilia are microtubule-based organelles protruding from almost all mammalian cells which, when dysfunctional, result in genetic disorders called "ciliopathies". High-throughput studies have revealed ...that cilia are composed of thousands of proteins. However, despite many efforts, much remains to be determined regarding the biological functions of this increasingly important complex organelle.
We have derived an online tool, from a systematic network-based approach to dissect the cilia/centrosome complex interactome (CCCI). The tool integrates all current available data into a model which provides an "interaction" perspective on ciliary function. We generated a network of interactions between human proteins organized into functionally relevant "communities", which can be defined as groups of genes that are both highly inter-connected and strongly co-expressed. We then combined sequence and co-expression data in order to identify the transcription factors responsible for regulating genes within their respective communities. Our analyses have discovered communities significantly specialized for delegating specific biological functions such as mRNA processing, protein translation, folding and degradation processes that had never been associated with ciliary proteins until now.
CCCI will allow us to clarify the roles of previously unknown ciliary functions, elucidate the molecular mechanisms underlying ciliary-associated phenotypes, and apply our knowledge of the functional roles of relatively uncharacterized molecular entities to disease phenotypes and new clinical applications.
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