underexpressed (miRNA-136, miRNA-147, miRNA-1250, miRNA-148a, miRNA-632, miRNA-646, miRNA668, miRNA-877, miRNA-503, miRNA-220a, miRNA-323-5p), and 2 miRNAs were overexpressed miRNA27b

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Dynamic protein-DNA interactions constitute highly robust cellular machineries to fulfill cellular functions. A vast number of studies have focused on how DNA-binding proteins search for and interact with their target DNA segments and on what cellular cues can regulate protein binding, for which protein concentration is a most obvious one. In contrast, how protein unbinding could be regulated by protein concentration has evaded attention because protein unbinding from DNA is typically a unimolecular reaction and thus concentration independent. Recent single-molecule studies from multiple research groups have uncovered that protein concentration can facilitate the unbinding of DNA-bound proteins, revealing regulation of protein unbinding as another mechanistic paradigm for gene regulation. In this Account, we review these recent in vitro and in vivo single-molecule experiments that uncovered the concentration-facilitated protein unbinding by multiple types of DNA-binding proteins, including sequence-nonspecific DNA-binding proteins (e.g., nucleoid-associated proteins, NAP), sequence-specific DNA-binding proteins (e.g., metal-responsive transcription regulators CueR and ZntR), sequence-neutral single-stranded DNA-binding proteins (e.g., Replication protein A, RPA), and DNA polymerases. For the in vitro experiments, Marko's group investigated the exchange of GFP-tagged DNA-bound NAPs with nontagged NAPs in solution of increasing concentration using single-molecule magnetic-tweezers fluorescence microscopy. The faster fluorescence intensity decrease with higher nontagged NAP concentrations suggests that DNA-bound NAPs undergo faster exchange with higher free NAP concentrations. Chen's group used single-molecule fluorescence resonance energy transfer measurements to study the unbinding of CueR from its cognate oligomeric DNA. The average microscopic dwell times of DNA-bound states become shorter with increasing CueR concentrations in the surroundings, demonstrating that free CueR proteins can facilitate the unbinding of the incumbent one on DNA through either assisted dissociation or direct substitution. Greene's group studied the unbinding of RPAs from single-stranded DNA using total internal reflection fluorescence microscopy and DNA curtain techniques. The fluorescence intensity versus time traces show faster decay with higher wild-type RPA concentrations, indicating that DNA-bound RPAs can undergo a concentration-facilitated exchange when encountering excess free RPA. van Oijen's group investigated the leading/lagging-strand polymerase exchange events in the bacteriophage T7 and E. coli replication systems using a combination of single-molecule fluorescence microscopy and DNA-flow-stretching assay. The processivity was observed to have larger decrease when the concentration of the Y526F polymerase mutant increases, indicating that the unbinding of the polymerase is also concentration-dependent. Using stroboscopic imaging and single-molecule tracking, Chen's group further advanced their study into living bacterial ...

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Summary Upon inhibition of respiration, which occurs in hypoxic or nitric oxide-containing host microenvironments, Mycobacterium tuberculosis (Mtb) adopts a non-replicating ‘quiescent’ state and becomes relatively unresponsive to antibiotic treatment. We used comprehensive mutant fitness analysis to identify regulatory and metabolic pathways that are essential for the survival of quiescent Mtb. This genetic study identified a protein acetyl-transferase (MtPat/Rv0998) that promoted survival and altered the flux of carbon from oxidative to reductive TCA reactions. Reductive TCA requires malate dehydrogenase (MDH) and maintains the redox state of the NAD+/NADH pool. Genetic or chemical inhibition of MDH resulted in rapid cell death in both hypoxic cultures and in murine lung. These phenotypic data, in conjunction with significant structural differences between human and mycobacterial MDH enzymes that could be exploited for drug development, suggest a new strategy for eradicating quiescent bacteria.

Candida auris is an emerging fatal fungal infection that has resulted in several outbreaks in hospitals and care facilities. Current treatment options are limited by the development of drug resistance. Identifying new pharmaceuticals to combat these drug-resistant infections will thus be required to overcome this unmet medical need. We have established a bioluminescent ATP-based assay to identify new compounds and potential drug combinations showing effective growth inhibition against multiple strains of multidrug resistant Candida auris. The assay is robust and suitable for assessing large compound collections by high throughput screening. Utilizing this assay, we conducted a screen of 4,314 approved drugs and pharmacologically active compounds which yielded 25 compounds including 6 novel anti-Candida auris compounds and 13 sets of potential two drug combinations. Among the drug combinations, the serine palmitoyltransferase inhibitor myriocin demonstrated a combinational effect with flucytosine against all tested isolates during screening. This combinational effect was confirmed in 13 clinical isolates of Candida auris.

Investigating the implementation and dissemination of evidence-based health-promotion programs to reach large numbers of diverse older adults is needed. The purpose of this study is to examine relationships between class size and session attendance and assess differences in intervention outcomes based on these community-based fall prevention program characteristics. Pre-post data were analyzed from 2,056 falls prevention program participants. PROC MIXED for repeated measures and ordinary least squares regressions were employed. Approximately 32% of participants enrolled in recommended class sizes (eight to 12 participants) and 76.4% of enrolled seniors attended more than five of eight sessions. Enrolling in smaller class sizes was associated with higher class attendance (X 2 =43.43, p<0.001). Recommended class sizes and those with 13-20 participants reported significant improvements in falls efficacy and physical activity. Perfect attendance was associated with improvements in falls efficacy (t=2.52, p<0.05) and activity limitation (t=−2.66, p<0.01). Findings can inform fall prevention program developers and lay leader deliverers about ideal class sizes relative to maximum intervention benefits and cost efficiency.