Pitt-Hopkins syndrome (PTHS) is a neurodevelopmental disorder caused by monoallelic mutation or deletion in the
(
) gene. Individuals with PTHS typically present in the first year of life with ...developmental delay and exhibit intellectual disability, lack of speech, and motor incoordination. There are no effective treatments available for PTHS, but the root cause of the disorder,
haploinsufficiency, suggests that it could be treated by normalizing
gene expression. Here, we performed proof-of-concept viral gene therapy experiments using a conditional
mouse model of PTHS and found that postnatally reinstating
expression in neurons improved anxiety-like behavior, activity levels, innate behaviors, and memory. Postnatal reinstatement also partially corrected EEG abnormalities, which we characterized here for the first time, and the expression of key TCF4-regulated genes. Our results support a genetic normalization approach as a treatment strategy for PTHS, and possibly other TCF4-linked disorders.
The lateral central nucleus of the amygdala (CeA
) and the dorsolateral bed nucleus of the stria terminalis (BNST
) coordinate the expression of shorter- and longer-lasting fears, respectively. Less ...is known about how these structures communicate with each other during fear acquisition. One pathway, from the CeA
to the BNST
, is thought to communicate via corticotropin-releasing factor (CRF), but studies have yet to examine its function in fear learning and memory. Thus, we developed an adeno-associated viral-based strategy to selectively target CRF neurons with the optogenetic silencer archaerhodopsin tp009 (CRF-ArchT) to examine the role of CeA
CRF neurons and projections to the BNST
during the acquisition of contextual fear. Expression of our CRF-ArchT vector injected into the amygdala was restricted to CeA
CRF neurons. Furthermore, CRF axonal projections from the CeA
clustered around BNST
CRF cells. Optogenetic silencing of CeA
CRF neurons during contextual fear acquisition disrupted retention test freezing 24 h later, but only at later time points (>6 min) during testing. Silencing CeA
CRF projections in the BNST
during contextual fear acquisition produced a similar effect. Baseline contextual freezing, the rate of fear acquisition, freezing in an alternate context after conditioning and responsivity to foot shock were unaffected by optogenetic silencing. Our results highlight how CeA
CRF neurons and projections to the BNST
consolidate longer-lasting components of a fear memory. Our findings have implications for understanding how discrete amygdalar CRF pathways modulate longer-lasting fear in anxiety- and trauma-related disorders.
Abstract
Biallelic mutations in interphotoreceptor matrix proteoglycan 2 (IMPG2) in humans cause retinitis pigmentosa (RP) with early macular involvement, albeit the disease progression varies widely ...due to genetic heterogeneity and IMPG2 mutation type. There are currently no treatments for IMPG2-RP. To aid preclinical studies toward eventual treatments, there is a need to better understand the progression of disease pathology in appropriate animal models. Toward this goal, we developed mouse models with patient mimicking homozygous frameshift (T807Ter) or missense (Y250C) Impg2 mutations, as well as mice with a homozygous frameshift mutation (Q244Ter) designed to completely prevent IMPG2 protein expression, and characterized the trajectory of their retinal pathologies across postnatal development until late adulthood. We found that the Impg2T807Ter/T807Ter and Impg2Q244Ter/Q244Ter mice exhibited early onset gliosis, impaired photoreceptor outer segment maintenance, appearance of subretinal deposits near the optic disc, disruption of the outer retina, and neurosensorial detachment, whereas the Impg2Y250C/Y250C mice exhibited minimal retinal pathology. These results demonstrate the importance of mutation type in disease progression in IMPG2-RP and provide a toolkit and preclinical data for advancing therapeutic approaches.
Farmland, foresiland, ranchland, wildlife habitat, and open space all continue to disappear at an alarming rate. Millions of acres of these valuable lands will change hands in the next 15 years. ...Preserving these lands is vital, and the use of conservation easements is essential in achieving this goal. Conservation easements have grown in popularity quicker than any other private land protection instrument. By permanently restricting development and land uses, conservation easements ensure traditional land-use values remain in place for the enjoyment of future generations. Do we need another strip mall replacing a forestiand? Another suburban housing tract in place of a family farm? Pressure to sell to the highest bidder leaves many private landowners little choice, despite their desire to preserve land for future generations. Prívate landowners need every incentive possible to preserve their lands, and conservation easements provide security and tax relief. However, barriers to the effective use of conservation easements remain in place, and tax incentives are insufficient for many private landowners of low to moderate income. This Comment discusses the history of conservation easements up to the present, and analyzes several barriers preventing even broader use of this valuable private land protection instrument.
The human gut contains a vast array of viruses, mostly bacteriophages. The majority remain uncharacterized, and their roles in shaping the gut microbiome and in impacting on human health remain ...poorly understood. We performed longitudinal metagenomic analysis of fecal viruses in healthy adults that reveal high temporal stability, individual specificity, and correlation with the bacterial microbiome. Using a database-independent approach that uses most of the sequencing data, we uncovered the existence of a stable, numerically predominant individual-specific persistent personal virome. Clustering of viral genomes and de novo taxonomic annotation identified several groups of crAss-like and Microviridae bacteriophages as the most stable colonizers of the human gut. CRISPR-based host prediction highlighted connections between these stable viral communities and highly predominant gut bacterial taxa such as Bacteroides, Prevotella, and Faecalibacterium. This study provides insights into the structure of the human gut virome and serves as an important baseline for hypothesis-driven research.
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•The human gut virome is highly individual and stable for up to 1 year•A stable and predominant fraction of viruses constitutes a persistent personal virome•Persistent bacteriophages can be linked to highly predominant gut bacterial taxa•Virulent crAss-like and Microviridae bacteriophages predominate and persist in the gut
Shkoporov et al. demonstrate high individual specificity and temporal stability of the human gut virome. They describe a numerically prevalent and persisting fraction of the viral community, termed persistent personal virome (PPV). The PPV consists mainly of virulent bacteriophages predicted to target major taxonomic groups of gut bacteria.
The human gut virome is thought to significantly impact the microbiome and human health. However, most virome analyses have been performed on a limited fraction of known viruses. Using whole-virome ...analysis on a published keystone inflammatory bowel disease (IBD) cohort and an in-house ulcerative colitis dataset, we shed light on the composition of the human gut virome in IBD beyond this identifiable minority. We observe IBD-specific changes to the virome and increased numbers of temperate phage sequences in individuals with Crohn’s disease. Unlike prior database-dependent methods, no changes in viral richness were observed. Among IBD subjects, the changes in virome composition reflected alterations in bacterial composition. Furthermore, incorporating both bacteriome and virome composition offered greater classification power between health and disease. This approach to analyzing whole virome across cohorts highlights significant IBD signals, which may be crucial for developing future biomarkers and therapeutics.
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•Analyzing viral dark matter changes our understanding of the gut virome•Gene-based clustering can address the challenges of high inter-individual variation•Healthy human gut virome is dominated by a stable core of virulent bacteriophages•In Crohn’s disease, the virulent core is replaced with temperate bacteriophages
In this study, Clooney et al. describe changes in the composition and function of the human gut virome by analyzing both known and unknown viral sequences. They provide evidence that a healthy core of virulent bacteriophage is replaced by temperate bacteriophage in inflammatory bowel disease.
CrAssphages represent the most abundant virus in the human gut microbiota, but the lack of available genome sequences for comparison has kept them enigmatic. Recently, sequence-based classification ...of distantly related crAss-like phages from multiple environments was reported, leading to a proposed familial-level taxonomic group. Here, we assembled the metagenomic sequencing reads from 702 human fecal virome/phageome samples and analyzed 99 complete circular crAss-like phage genomes and 150 contigs ≥70 kb. In silico comparative genomics and taxonomic analysis enabled a classification scheme of crAss-like phages from human fecal microbiomes into four candidate subfamilies composed of ten candidate genera. Laboratory analysis was performed on fecal samples from an individual harboring seven distinct crAss-like phages. We achieved crAss-like phage propagation in ex vivo human fecal fermentations and visualized short-tailed podoviruses by electron microscopy. Mass spectrometry of a crAss-like phage capsid protein could be linked to metagenomic sequencing data, confirming crAss-like phage structural annotations.
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•Screening of human fecal metagenomic samples reveals 249 crAss-like phage genomes•The crAss-like phages were classified into 4 subfamilies composed of 10 candidate genera•A crAss-like phage was propagated in ex vivo human fecal fermentations•Short-tailed phage virions could be visualized by electron microscopy
CrAssphage is the most abundant human gut-associated virus. Guerin et al. identify 249 crAss-like phage genomes and classify them into four subfamilies and ten candidate genera that differ among human populations. These in silico predictions are combined with ex vivo propagations, electron microscopy imaging, and mass spectrometry detection.
Bacteriophages (phages) or bacterial viruses have been proposed as natural antimicrobial agents to fight against antibiotic-resistant bacteria associated with human infections.
is a gut commensal, ...which is occasionally found in the mouth and vaginal tract, and does not usually cause clinical problems. However, it can spread to other areas of the body and cause life-threatening infections, such as septicemia, endocarditis, or meningitis, in immunocompromised hosts. Although
phage cocktails are not commercially available within the EU or USA, there is an accumulated evidence from in vitro and in vivo studies that have shown phage efficacy, which supports the idea of applying phage therapy to overcome infections associated with
. In this review, we discuss the potency of bacteriophages in controlling
, in both in vitro and in vivo scenarios.
associated bacteriophages were compared at the genome level and an attempt was made to categorize phages with respect to their suitability for therapeutic application, using orthocluster analysis. In addition,
phages have been examined for the presence of antibiotic-resistant genes, to ensure their safe use in clinical conditions. Finally, the domain architecture of
phage-encoded endolysins are discussed.
The human microbiome and its importance in health and disease have been the subject of numerous research articles. Most microbes reside in the digestive tract, with up to 10
cells per gram of faecal ...material found in the colon. In terms of gene number, it has been estimated that the gut microbiome harbours >100 times more genes than the human genome. Several human intestinal diseases are strongly associated with disruptions in gut microbiome composition. Less studied components of the gut microbiome are the bacterial viruses called bacteriophages that may be present in numbers equal to or greater than the prokaryotes. Their potential to lyse their bacterial hosts, or to act as agents of horizontal gene transfer makes them important research targets. In this study in vitro faecal fermentation systems were developed and compared for their ability to act as surrogates for the human colon. Changes in bacterial and viral composition occurred after introducing a high-titre single phage preparation both with and without a known bacterial host during the 24 h-long fermentation. We also show that during this timeframe 50 mL plastic tubes can provide data similar to that generated in a sophisticated faecal fermenter system. This knowledge can guide us to a better understanding of the short-term impact of bacteriophage transplants on the bacteriomes and viromes of human recipients.
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