Histone deacetylases (HDACs) are part of a vast family of enzymes that have crucial roles in numerous biological processes, largely through their repressive influence on transcription. The expression of many HDAC isoforms in eukaryotic cells raises questions about their possible specificity or redundancy, and whether they control global or specific programmes of gene expression. Recent analyses of HDAC knockout mice have revealed highly specific functions of individual HDACs in development and disease. Mutant mice lacking individual HDACs are a powerful tool for defining the functions of HDACs in vivo and the molecular targets of HDAC inhibitors in disease.

The many roles of histone deacetylases in development and physiology: Implications for disease and therapy

To investigate the occurrence of olfactory and gustatory dysfunctions in patients with laboratory-confirmed COVID-19 infection. Patients with laboratory-confirmed COVID-19 infection were recruited from 12 European hospitals. The following epidemiological and clinical outcomes have been studied: age, sex, ethnicity, comorbidities, and general and otolaryngological symptoms. Patients completed olfactory and gustatory questionnaires based on the smell and taste component of the National Health and Nutrition Examination Survey, and the short version of the Questionnaire of Olfactory Disorders-Negative Statements (sQOD-NS). A total of 417 mild-to-moderate COVID-19 patients completed the study (263 females). The most prevalent general symptoms consisted of cough, myalgia, and loss of appetite. Face pain and nasal obstruction were the most disease-related otolaryngological symptoms. 85.6% and 88.0% of patients reported olfactory and gustatory dysfunctions, respectively. There was a significant association between both disorders (p < 0.001). Olfactory dysfunction (OD) appeared before the other symptoms in 11.8% of cases. The sQO-NS scores were significantly lower in patients with anosmia compared with normosmic or hyposmic individuals (p = 0.001). Among the 18.2% of patients without nasal obstruction or rhinorrhea, 79.7% were hyposmic or anosmic. The early olfactory recovery rate was 44.0%. Females were significantly more affected by olfactory and gustatory dysfunctions than males (p = 0.001). Olfactory and gustatory disorders are prevalent symptoms in European COVID-19 patients, who may not have nasal symptoms. The sudden anosmia or ageusia need to be recognized by the international scientific community as important symptoms of the COVID-19 infection.

https://link.springer.com/content/pdf/10.1007/s00405-020-05965-1.pdf

Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study.

Viral infections have detrimental impacts on neurological functions, and even to cause severe neurological damage. Very recently, coronaviruses (CoV), especially severe acute respiratory syndrome CoV 2 (SARS-CoV-2), exhibit neurotropic properties and may also cause neurological diseases. It is reported that CoV can be found in the brain or cerebrospinal fluid. The pathobiology of these neuroinvasive viruses is still incompletely known, and it is therefore important to explore the impact of CoV infections on the nervous system. Here, we review the research into neurological complications in CoV infections and the possible mechanisms of damage to the nervous system.

/pdf/nervous-system-involvement-after-infection-with-covid-19-and-1wvkcokhlc.pdf

Nervous system involvement after infection with COVID-19 and other coronaviruses

https://demystifyingmedicine.od.nih.gov/DM14/2014-02-11/Cell-y2013v155p540.pdf

Replication-Competent Noninduced Proviruses in the Latent Reservoir Increase Barrier to HIV-1 Cure

Despite antiretroviral therapy, proviral latency of human immunodeficiency virus type 1 (HIV-1) remains a principal obstacle to curing the infection. Inducing the expression of latent genomes within resting CD4(+) T cells is the primary strategy to clear this reservoir. Although histone deacetylase inhibitors such as suberoylanilide hydroxamic acid (also known as vorinostat, VOR) can disrupt HIV-1 latency in vitro, the utility of this approach has never been directly proven in a translational clinical study of HIV-infected patients. Here we isolated the circulating resting CD4(+) T cells of patients in whom viraemia was fully suppressed by antiretroviral therapy, and directly studied the effect of VOR on this latent reservoir. In each of eight patients, a single dose of VOR increased both biomarkers of cellular acetylation, and simultaneously induced an increase in HIV RNA expression in resting CD4(+) cells (mean increase, 4.8-fold). This demonstrates that a molecular mechanism known to enforce HIV latency can be therapeutically targeted in humans, provides proof-of-concept for histone deacetylase inhibitors as a therapeutic class, and defines a precise approach to test novel strategies to attack and eradicate latent HIV infection directly.

/pdf/administration-of-vorinostat-disrupts-hiv-1-latency-in-4cer52vaae.pdf

Administration of vorinostat disrupts HIV-1 latency in patients on antiretroviral therapy

The generation of an effective method for stimulating neuronal growth in specific directions, along well-defined geometries, and in numerous cells could impact areas ranging from fundamental studies of neuronal evolution and morphogenesis, to applications in biomedical diagnostics and nerve regeneration. Applied mechanical stress can regulate neurite growth. Indeed, previous studies have shown that neuronal cells can develop and extend neurites with rapid growth rates under applied “towing” tensions imparted by micropipettes. Yet, such methods are complex and exhibit low throughputs, as the tension is applied serially to individual cells. Here we present a novel approach to inducing neurite growth in multiple cells in parallel, by using a miniaturized platform with numerous microchannels. Upon connection of a vacuum to these microchannels, tension can be applied on multiple cells simultaneously to induce the growth of neurites. A theoretical model was also developed to understand the effect of tension on the dynamics of neurite development.

/pdf/tension-induced-neurite-growth-in-microfluidic-channels-2d3ed4xr44.pdf

Tension-induced neurite growth in microfluidic channels.

Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution.

/pdf/open-led-illuminator-a-simple-and-inexpensive-led-7rvft520uu.pdf

Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons.

Fluorescent protein fusions to herpesvirus capsids have proven to be a valuable method to study virus particle transport in living cells. Fluorescent protein fusions to the amino terminus of small capsid protein VP26 are the most widely used method to visualize pseudorabies virus (PRV) and herpes simplex virus (HSV) particles in living cells. However, these fusion proteins do not incorporate to full occupancy and have modest effects on virus replication and pathogenesis. Recent cryoelectron microscopy studies have revealed that herpesvirus small capsid proteins bind to capsids via their amino terminus, whereas the carboxy terminus is unstructured and therefore may better tolerate fluorescent protein fusions. Here, we describe a new recombinant PRV expressing a carboxy-terminal VP26-mCherry fusion. Compared to previously characterized viruses expressing amino-terminal fusions, this virus expresses more VP26 fusion protein in infected cells and incorporates more VP26 fusion protein into virus particles, and individual virus particles exhibit brighter red fluorescence. We performed single-particle tracking of fluorescent virus particles in primary neurons to measure anterograde and retrograde axonal transport, demonstrating the usefulness of this novel VP26-mCherry fusion for the study of viral intracellular transport.IMPORTANCE Alphaherpesviruses are among the very few viruses that are adapted to invade the mammalian nervous system. Intracellular transport of virus particles in neurons is important, as this process underlies both mild peripheral nervous system infection and severe spread to the central nervous system. VP26, the small capsid protein of HSV and PRV, was one of the first herpesvirus proteins to be fused to a fluorescent protein. Since then, these capsid-tagged virus mutants have become a powerful tool to visualize and track individual virus particles. Improved capsid tags will facilitate fluorescence microscopy studies of virus particle intracellular transport, as a brighter particle will improve localization accuracy of individual particles and allow for shorter exposure times, reducing phototoxicity and improving the time resolution of particle tracking in live cells.

Functional Carboxy-Terminal Fluorescent Protein Fusion to Pseudorabies Virus Small Capsid Protein VP26.

Correction for '3D printed nervous system on a chip' by Blake N. Johnson et al., Lab Chip, 2016, 16, 1393-1400.

/pdf/correction-3d-printed-nervous-system-on-a-chip-4o0mb7hpvm.pdf

Correction: 3D printed nervous system on a chip

Alphaherpesvirus tegument assembly, secondary envelopment, and exocytosis processes are understood in broad strokes, but many of the individual steps in this pathway, and their molecular and cell biological details, remain unclear. Viral tegument and membrane proteins form an extensive and robust protein interaction network, such that essentially any structural protein can be deleted, yet particles are still assembled, enveloped, and released from infected cells. We conceptually divide the tegument proteins into three groups: conserved inner and outer teguments that participate in nucleocapsid and membrane contacts, respectively; and 'middle' tegument proteins, consisting of some of the most abundant tegument proteins that serve as central hubs in the protein interaction network, yet which are unique to the alphaherpesviruses. We then discuss secondary envelopment, reviewing the tegument-membrane contacts and cellular factors that drive this process. We place this viral process in the context of cell biological processes, including the endocytic pathway, ESCRT machinery, autophagy, secretory pathway, intracellular transport, and exocytosis mechanisms. Finally, we speculate about potential relationships between cellular defenses against oligomerizing or aggregating membrane proteins and the envelopment and egress of viruses.

/pdf/tegument-assembly-secondary-envelopment-and-exocytosis-36z5fnzpp8.pdf

Ian B. Hogue

Papers

Tension-induced neurite growth in microfluidic channels.

Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons.

Functional Carboxy-Terminal Fluorescent Protein Fusion to Pseudorabies Virus Small Capsid Protein VP26.

Correction: 3D printed nervous system on a chip

Tegument Assembly, Secondary Envelopment and Exocytosis