More than a Feeling: Dermatological Changes Impacted by Spaceflight

Spaceflight poses a unique set of challenges to humans and the hostile Spaceflight environment can induce a wide range of increased health risks, including dermatological issues. The biology driving the frequency of skin issues in astronauts is currently not well understood. To address this issue, we used a systems biology approach utilizing NASA's Open Science Data Repository (OSDR) on spaceflown murine transcriptomic datasets focused on the skin, biomedical profiles from fifty NASA astronauts, and confirmation via transcriptomic data from JAXA astronauts, the NASA Twins Study, and the first civilian commercial mission, Inspiration4. Key biological changes related to skin health, DNA damage & repair, and mitochondrial dysregulation were determined to be involved with skin health risks during Spaceflight. Additionally, a machine learning model was utilized to determine key genes driving Spaceflight response in the skin. These results can be used for determining potential countermeasures to mitigate Spaceflight damage to the skin.

System-wide transcriptome damage and tissue identity loss in COVID-19 patients

The molecular mechanisms underlying the clinical manifestations of coronavirus disease 2019 (COVID-19), and what distinguishes them from common seasonal influenza virus and other lung injury states such as acute respiratory distress syndrome, remain poorly understood. To address these challenges, we combine transcriptional profiling of 646 clinical nasopharyngeal swabs and 39 patient autopsy tissues to define body-wide transcriptome changes in response to COVID-19. We then match these data with spatial protein and expression profiling across 357 tissue sections from 16 representative patient lung samples and identify tissue-compartment-specific damage wrought by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, evident as a function of varying viral loads during the clinical course of infection and tissue-type-specific expression states. Overall, our findings reveal a systemic disruption of canonical cellular and transcriptional pathways across all tissues, which can inform subsequent studies to combat the mortality of COVID-19 and to better understand the molecular dynamics of lethal SARS-CoV-2 and other respiratory infections.

The Great Deceiver: miR-2392's Hidden Role in Driving SARS-CoV-2 Infection

MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional gene regulation that have a major impact on many diseases and provides an exciting avenue towards antiviral therapeutics. From patient transcriptomic data, we have discovered a circulating miRNA, miR-2392, that is directly involved with SARS-CoV-2 machinery during host infection. Specifically, we show that miR-2392 is key in driving downstream suppression of mitochondrial gene expression, increasing inflammation, glycolysis, and hypoxia as well as promoting many symptoms associated with COVID-19 infection. We demonstrate miR-2392 is present in the blood and urine of COVID-19 positive patients, but not detected in COVID-19 negative patients. These findings indicate the potential for developing a novel, minimally invasive, COVID-19 detection method. Lastly, using in vitro human and in vivo hamster models, we have developed a novel miRNA-based antiviral therapeutic that targets miR-2392, significantly reduces SARS-CoV-2 viability in hamsters and may potentially inhibit a COVID-19 disease state in humans.

Systemic Tissue and Cellular Disruption from SARS-CoV-2 Infection revealed in COVID-19 Autopsies and Spatial Omics Tissue Maps

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus has infected over 115 million people and caused over 2.5 million deaths worldwide. Yet, the molecular mechanisms underlying the clinical manifestations of COVID-19, as well as what distinguishes them from common seasonal influenza virus and other lung injury states such as Acute Respiratory Distress Syndrome (ARDS), remains poorly understood. To address these challenges, we combined transcriptional profiling of 646 clinical nasopharyngeal swabs and 39 patient autopsy tissues, matched with spatial protein and expression profiling (GeoMx) across 357 tissue sections. These results define both body-wide and tissue-specific (heart, liver, lung, kidney, and lymph nodes) damage wrought by the SARS-CoV-2 infection, evident as a function of varying viral load (high vs. low) during the course of infection and specific, transcriptional dysregulation in splicing isoforms, T cell receptor expression, and cellular expression states. In particular, cardiac and lung tissues revealed the largest degree of splicing isoform switching and cell expression state loss. Overall, these findings reveal a systemic disruption of cellular and transcriptional pathways from COVID-19 across all tissues, which can inform subsequent studies to combat the mortality of COVID-19, as well to better understand the molecular dynamics of lethal SARS-CoV-2 infection and other viruses.

Muscle ring finger-3 protects against diabetic cardiomyopathy induced by a high fat diet

BACKGROUND

The pathogenesis of diabetic cardiomyopathy (DCM) involves the enhanced activation of peroxisome proliferator activating receptor (PPAR) transcription factors, including the most prominent isoform in the heart, PPARα. In cancer cells and adipocytes, post-translational modification of PPARs have been identified, including ligand-dependent degradation of PPARs by specific ubiquitin ligases. However, the regulation of PPARs in cardiomyocytes and heart have not previously been identified. We recently identified that muscle ring finger-1 (MuRF1) and MuRF2 differentially inhibit PPAR activities by mono-ubiquitination, leading to the hypothesis that MuRF3 may regulate PPAR activity in vivo to regulate DCM.

METHODS

MuRF3-/- mice were challenged with 26 weeks 60% high fat diet to induce insulin resistance and DCM. Conscious echocardiography, blood glucose, tissue triglyceride, glycogen levels, immunoblot analysis of intracellular signaling, heart and skeletal muscle morphometrics, and PPARα, PPARβ, and PPARγ1 activities were assayed.

RESULTS

MuRF3-/- mice exhibited a premature systolic heart failure by 6 weeks high fat diet (vs. 12 weeks in MuRF3+/+). MuRF3-/- mice weighed significantly less than sibling-matched wildtype mice after 26 weeks HFD. These differences may be largely due to resistance to fat accumulation, as MRI analysis revealed MuRF3-/- mice had significantly less fat mass, but not lean body mass. In vitro ubiquitination assays identified MuRF3 mono-ubiquitinated PPARα and PPARγ1, but not PPARβ.

CONCLUSIONS

These findings suggest that MuRF3 helps stabilize cardiac PPARα and PPARγ1 in vivo to support resistance to the development of DCM. MuRF3 also plays an unexpected role in regulating fat storage despite being found only in striated muscle.

Abstract 627: The Smooth Muscle-selective RhoGAP Graf3 Is A Critical Regulator Of Vascular Tone And Hypertension

Our ability to effectively treat hypertensive patients is limited by an incomplete understanding of its origin. Activation of RhoA in vascular smooth muscle cells (SMC) has been implicated in the development of vasoconstrictor-induced hypertension (HTN), but until now, the extent that RhoA contributed to basal BP was unknown and the mechanisms that limit RhoA activity in SMC were undetermined. We identified GRAF3 as a RhoA-GAP expressed specifically in SMC in mice and humans and reported that our novel global GRAF3-deficient mice exhibit significant basal HTN (+ 25 mm Hg) that was fully reversed by treatment with a Rho-kinase inhibitor ( Nature Comm. 2013;4:2910 ). One objective of this new study was to test if elevated RhoA-dependent myogenic tone was causal for HTN in global GRAF3-deficient (GRAF3 gt/gt ) mice. Importantly, normal GRAF3 expression can be permanently restored by Cre recombinase-dependent excision in our model. Thus, we crossed the GRAF3 gt/gt mice to the tamoxifen-inducible SM-specific SM MHC- CreER T2 line and measured BP before and after tamoxifen treatment (1mg i.p. for 5 consecutive days). Tamoxifen induced SMC-GRAF3 re-expression and resulted in a complete reversal of MAP (from 123 mmHg to 95 mm Hg). Moreover, RhoA activity and myosin light chain phosphorylation were elevated 2-fold in GRAF3-depleted SMC in vitro and in vivo and isolated vessel segments from GRAF3-deficient mice showed a 2.5 fold increase in Rho kinase-dependent Ang II-induced contractility. Collectively, these findings provide unequivocal evidence that GRAF3 levels in SMC control basal BP homeostasis and that elevated BP in GRAF3 gt/gt mice is due to an enhanced, reversible, SMC contractile phenotype. A second objective was to determine whether GRAF3 variations are causally linked to cardiovascular outcomes in hypertensive patients. We found a clear and significant increase in minor allele frequency of a hypertensive GRAF3 locus in patients with HTN and coronary artery disease versus healthy volunteers (0.19 versus 0.30; p<0.05; N=920) and this association was significant regardless of race. Our studies provide a potential mechanism for the hypertensive locus identified within GRAF3 and provide the foundation for the future development of innovative HTN therapies.

All the little pieces. -Regulation of mitochondrial fusion and fission by ubiquitin and small ubiquitin-like modifer and their potential relevance in the heart.-

Mitochondria are dynamic organelles that undergo a constant cycle of division and fusion to maintain their function. The process of mitochondrial fusion has the effect of mixing their content, allowing complementation of protein components, mtDNA repair, and distribution of metabolic intermediates. Fission, on the other hand, enables mitochondria to increase in number and capacity, and to segregate mitochondria for autophagy by the lysosome ("mitophagy"). Disruption of these protein quality control mechanisms has recently been identified in multiple cardiac diseases, including cardiac hypertrophy, heart failure, dilated cardiomyopathy, and ischemic heart disease, and is intimately tied to mitochondrial control of apoptosis. Proteins that regulate mitochondrial fusion and fission have been discovered, including Mfn1, Mfn2, and Opa1 (fusion) and Drp1 and Fis1 (fission). In this review, we discuss how these proteins are regulated by post-translational modification with ubiquitin and SUMO (small ubiquitin-like modifier). We then present what is known about the ubiquitin and SUMO ligases that regulate these post-translational modifications and regulation of mitochondrial fusion and fission, exploring their potential as therapeutic targets of cardiac disease.

An experimental and theoretical study of the inhibition of Escherichia coli lac operon gene expression by antigene oligonucleotides

Previously, we have developed a genetically structured mathematical model to describe the inhibition of Escherichia coli lac operon gene expression by antigene oligos. Our model predicted that antigene oligos targeted to the operator region of the lac operon would have a significant inhibitory effect on beta-galactosidase production. In this investigation, the E. coli lac operon gene expression in the presence of antigene oligos was studied experimentally. A 21-mer oligo, which was designed to form a triplex with the operator, was found to be able to specifically inhibit beta-galactosidase production in a dose-dependent manner. In contrast to the 21-mer triplex-forming oligonucleotide (TFO), several control oligos showed no inhibitory effect. The ineffectiveness of the various control oligos, along with the fact that the 21-mer oligo has no homology sequence with lacZYA, and no mRNA is transcribed from the operator, suggests that the 21-mer oligo inhibits target gene expression by an antigene mechanism. To simulate the kinetics of lac operon gene expression in the presence of antigene oligos, a genetically structured kinetic model, which includes transport of oligo into the cell, growth of bacteria cells, and lac operon gene expression, was developed. Predictions of the kinetic model fit the experimental data quite well after adjustment of the value of the oligonucleotide transport rate constant (9.0 x 10(-)(3) min(-)(1)) and oligo binding affinity constant (1.05 x 10(6) M(-)(1)). Our values for these two adjusted parameters are in the range of reported literature values.