Oxidation of 5-methylcytosine in DNA by ten-eleven translocation (Tet) family of enzymes has been demonstrated to play a significant role in epigenetic regulation in mammals. We found that Tet enzymes also possess the activity of catalyzing the formation of 5-hydroxymethylcytidine (5-hmrC) in RNA in vitro. In addition, the catalytic domains of all three Tet enzymes as well as full-length Tet3 could induce the formation of 5-hmrC in human cells. Moreover, 5-hmrC was present at appreciable levels (∼1 per 5000 5-methylcytidine) in RNA of mammalian cells and tissues. Our results suggest the involvement of this oxidation in RNA biology.

SUMMARY Cytosine DNA methylation is an epigenetic mark in most eukaryotic cells that regulates numerous processes, including gene expression and stress responses. We performed a genome-wide analysis of DNA methylation in the human malaria parasite Plasmodium falciparum. We mapped the positions of methylated cytosines and identified a single functional DNA methyltransferase, PfDNMT, that may mediate these genomic modifications. These analyses revealed that the malaria genome is asymmetrically methylated, in which only one DNA strand is methylated, and shares common features with undifferentiated plant and mammalian cells. Notably, core promoters are hypomethylated and transcript levels correlate with intra-exonic methylation. Additionally, there are sharp methylation transitions at nucleosome and exon-intron boundaries. These data suggest that DNA methylation could regulate virulence gene expression and transcription elongation. Furthermore, the broad range of action of DNA methylation and uniqueness of PfDNMT suggest that the methylation pathway is a potential target for anti-malarial strategies.

Background: Because its N terminus adopts an APK motif, DDB2 might be ␣-N-methylated. Results: We examined the nature of DDB2 ␣-N-methylation, the enzyme involved in this methylation and its function in DNA repair. Conclusion: DDB2 could be ␣-N-methylated by NRMT, and this methylation facilitated the recruitment of DDB2 to DNA damage foci. Significance: This work expands the function of protein ␣-N-methylation to DNA repair.

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Neural stem cell (NSC) transplantation has been proposed as a future therapy for neurodegenerative disorders. However, NSC transplantation will be hampered by the limited number of brain donors and the toxicity of immunosuppressive regimens that might be needed with allogeneic transplantation. These limitations may be avoided if NSCs can be generated from clinically accessible sources, such as bone marrow (BM) and peripheral blood samples, that are suitable for autologous transplantation. We report here that NSCs can be generated from human BM-derived mesenchymal stem cells (MSCs). When cultured in NSC culture conditions, 8% of MSCs were able to generate neurospheres. These MSC-derived neurospheres expressed characteristic NSC antigens, such as nestin and musashi-1, and were capable of self-renewal and multilineage differentiation into neurons, astrocytes, and oligodendrocytes. Furthermore, when these MSC-derived neurospheres were cocultured with primary astrocytes, they differentiate into neurons that possess both dendritic and axonal processes, form synapses, and are able to fi re tetrodotoxin-sensitive action potentials. When these MSC-derived NSCs were switched back to MSC culture conditions, a small fraction of NSCs (averaging 4-5%) adhered to the culture fl asks, proliferated, and displayed the morphology of MSCs. Those adherent cells expressed the characteristic MSC antigens and regained the ability to differentiate into multiple mesodermal lineages. Data presented in this study suggest that MSCs contain a small fraction (averaging 4-5%) of a bipotential stem cell population that is able to generate either MSCs or NSCs depending on the culture conditions.

Extracellular adenosine (ADO), present in high concentrations in the tumor microenvironment (TME), suppresses immune function via inhibition of T cell and NK cell activation. Intratumoral generation of ADO depends on the sequential catabolism of ATP by two ecto-nucleotidases, CD39 (ATP → AMP) and CD73 (AMP → ADO). Inhibition of CD73 eliminates a major pathway of ADO production in the TME and can reverse ADO-mediated immune suppression. Extensive interrogation of structure−activity relationships (SARs), structure-based drug design, and optimization of pharmacokinetic properties culminated in the discovery of AB680, a highly potent (K i = 5 pM), reversible, and selective inhibitor of CD73. AB680 is further characterized by very low clearance and long half-lives across preclinical species, resulting in a PK profile suitable for long-acting parenteral administration. AB680 is currently being evaluated in phase 1 clinical trials. Initial data show AB680 is well tolerated and exhibits a pharmacokinetic profile suitable for biweekly (Q2W) iv-administration in human.

Mutations in the FOXP2 gene cause speech and language impairments, accompanied by structural and functional abnormalities in brain regions underlying speech-related sensory-motor processing, including the striatum and cerebellum. The sequence and expression patterns of FOXP2 are highly conserved among higher vertebrates. In the zebra finch brain, FoxP2 is expressed in Area X, a striatal nucleus required for vocal learning, and reduced FoxP2 expression impairs dendritic development and vocal learning. The FoxP2 gene encodes a transcription factor that controls the expression of many downstream genes. However, how FOXP2 gene expression is regulated is not clearly understood. miRNAs regulate gene expression post-transcriptionally by targeting the 3Ј-untranslated regions (UTRs) of mRNAs, leading to translational suppression or mRNA degradation. In this study, we identified miR-9 and miR-140-5p as potential regulators of the FoxP2 gene. We show that both miR-9 and miR-140-5p target specific sequences in the FoxP2 3Ј-UTR and downregulate FoxP2 protein and mRNA expression in vitro. We also show that the expression of miR-9 and miR-140-5p in Area X of the zebra finch brain is regulated during song development in juvenile zebra finches. We further show that in adult zebra finches the expression of miR-9 and miR-140-5p in Area X is regulated as a function of the social context of song behavior in males singing undirected songs. Our findings reveal a post-transcriptional mechanism that regulates FoxP2 expression and suggest that social vocal behavior can influence the basal ganglia circuit controlling vocal learning via a miRNA-FoxP2 gene regulatory network.

Ventilator-associated pneumonia remains a leading cause of morbidity and mortality in intensive care unit, and implementing effective oral care can reduce the incidence of ventilator-associated pneumonia. Chlorhexidine of 0·12% is recommended in our study.