Human DDX3 functions in translation and interacts with the translation initiation factor eIF3

The conserved RNA helicase DDX3 is of major medical importance due to its involvement in numerous cancers, human hepatitis C virus (HCV) and HIV. Although DDX3 has been reported to have a wide variety of cellular functions, its precise role remains obscure. Here, we raised a new antibody to DDX3 and used it to show that DDX3 is evenly distributed throughout the cytoplasm at steady state. Consistent with this observation, HA-tagged DDX3 also localizes to the cytoplasm. RNAi of DDX3 in both human and Drosophila cells shows that DDX3 is required for cell viability. Moreover, using RNAi, we show that DDX3 is required for expression of protein from reporter constructs. In contrast, we did not detect a role for DDX3 in nuclear steps in gene expression. Further insight into the function of DDX3 came from the observation that its major interaction partner is the multi-component translation initiation factor eIF3. We conclude that a primary function for DDX3 is in protein translation, via an interaction with eIF3

A global comparison between nuclear and cytosolic transcriptomes reveals differential compartmentalization of alternative transcript isoforms

Transcriptome analyses have typically disregarded nucleocytoplasmic differences. This approach has ignored some post-transcriptional regulations and their effect on the ultimate protein expression levels. Despite a longstanding interest in the differences between the nuclear and cytosolic transcriptomes, it is only recently that data have become available to study such differences and their associated features on a genome-wide scale. Here, we compared the nuclear and cytosolic transcriptomes of HepG2 and HeLa cells. HepG2 and HeLa cells vary significantly in the differential compartmentalization of their transcript isoforms, indicating that nucleocytoplasmic compartmentalization is a cell-specific characteristic. The differential compartmentalization is manifested at the transcript isoform level instead of the gene level because alternative isoforms of one gene can display different nucleocytoplasmic distributions. The isoforms enriched in the cytosol tend to have more introns and longer introns in their pre-mRNAs. They have more functional RNA folds and unique exons in the 3′ regions. These isoforms are more conserved than the isoforms enriched in the nucleus. Surprisingly, the presence of microRNAs does not have a significant impact on the nucleocytoplasmic distribution of their target isoforms. In contrast, nonsense-mediated decay is significantly more associated with the isoforms enriched in the nucleus than those enriched in the cytosol

The cardiomyocyte disrupts pyrimidine biosynthesis in non-myocytes to regulate heart repair

Various populations of cells are recruited to the heart after cardiac injury, but little is known about whether cardiomyocytes directly regulate heart repair. Using a murine model of ischemic cardiac injury, we demonstrate that cardiomyocytes play a pivotal role in heart repair by regulating nucleotide metabolism and fates of nonmyocytes. Cardiac injury induced the expression of the ectonucleotidase ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which hydrolyzes extracellular ATP to form AMP. In response to AMP, cardiomyocytes released adenine and specific ribonucleosides that disrupted pyrimidine biosynthesis at the orotidine monophosphate (OMP) synthesis step and induced genotoxic stress and p53-mediated cell death of cycling nonmyocytes. As nonmyocytes are critical for heart repair, we showed that rescue of pyrimidine biosynthesis by administration of uridine or by genetic targeting of the ENPP1/AMP pathway enhanced repair after cardiac injury. We identified ENPP1 inhibitors using small molecule screening and showed that systemic administration of an ENPP1 inhibitor after heart injury rescued pyrimidine biosynthesis in nonmyocyte cells and augmented cardiac repair and postinfarct heart function. These observations demonstrate that the cardiac muscle cell regulates pyrimidine metabolism in nonmuscle cells by releasing adenine and specific nucleosides after heart injury and provide insight into how intercellular regulation of pyrimidine biosynthesis can be targeted and monitored for augmenting tissue repair

EVALUATION OF LOW-PRESSURE WATER-BASED TRENCH DRAIN FIRE SUPPRESSION SYSTEMS IN AIRCRAFT HANGARS USING FDS MODELING

The 2020 National Defense Authorization Act (NDAA) prohibition of PFAS-containing AFFF fire protection systems by 2024 has motivated the U.S. Department of Defense to study other alternatives. In this study, the current low-expansion AFFF foam fire suppression systems with trenches layout in NAVFAC facilities are modeled as water-based systems to determine the scale, coverage, and extinguishment times that can be expected from such systems. A reduced spacing of the trenches is then simulated to determine how spacing of the floor nozzles affects fire suppression and control. Additionally, a model of a previously identified floor-level low-pressure water mist nozzle with the incorporation of trenches is studied to validate its possibility of being a replacement option for the current NAVFAC systems. Each simulation consists of three components: fire model, sprinkler/water mist model, and extinction model. Each model is evaluated separately before inputting into the final simulations to determine the most accurate representation and minimize uncertainties. The final simulations with sprinkler nozzles show successful extinguishment up to 23 MW and better performance at earlier activation time and in setups with the current trench spacing. Little to no difference is observed between the two fuel spill fire scenarios at the same activation time and trench spacing. On the other hand, the low-pressure water mist systems do not meet adequate performance in the final hangar simulations

The effect of amitriptyline treatment on the growth hormone response to apomorphine.

The growth hormone response to subcutaneous administration of the dopamine agonist apomorphine (0.005 mg/kg) was assessed in six normal male subjects before and at the end of a course of amitriptyline. Amitriptyline treatment significantly reduced the growth hormone response to apomorphine, confirming the findings of an earlier study in depressed patients. The way in which amitriptyline attenuates the effect of apomorphine is not clear. Direct blockade of dopamine receptors in the hypothalamus is a possibility, but long-term amitriptyline treatment could result in adaptive changes in the monoamine pathways which control GH release