We report on a new class of thermoresponsive biodegradable polyesters (TR-PE) inspired by polyacrylamides and elastin-like proteins (ELPs). The polyesters display reversible phase transition with tunable cloud point temperatures (T cp ) in aqueous solution as evidenced by UV−vis spectroscopy, 1 H NMR, and DLS measurements. These polyesters form coacervate droplets above their lower critical solution temperature (LCST). The T cp of the polyesters is influenced by the solutes such as urea, SDS, and NaCl. The T cp of the copolymers shows a linear correlation with the composition of the polyesters indicating the ability to tune the phase change temperature. We also show that such thermoresponsive coacervates are capable of encapsulating small molecules such as Nile Red. Furthermore, the polyesters are hydrolytically degradable.
Highlights d Bump-hole strategy developed for selective site-directed RNA editing (SDRE) system d SDRE in vitro and in human cells with bulky mutant ADAR2 proteins and guide RNAs d Directed editing on endogenous targets with reduced offtarget activity d Crystal structure of ADAR2-D E488Y with RNA duplex containing reduced abasic site
Structure–property correlation studies of a diverse set of biodegradable thermoresponsive polyesters provides a rationale for the design of thermoresponsive polyesters with desired cloud points.
Straightforwardm ethods for detecting adenosine-to-inosine (A-to-I) RNA editinga re key to ab etter understanding of its regulation, function, and connection with disease. Wea ddress this need by developing an ovel reagent, N-(4-ethynylphenyl)acrylamide (EPhAA), and illustrating its ability to selectively label inosine in RNA. EPhAA is synthesized in as ingle step, reacts rapidlyw ith inosine, and is "click"-compatible, enabling flexible attachment of fluorescent probesa te diting sites. We first validate EPhAA reactivity and selectivityf or inosine in both ribonucleosides and RNA substrates, and then apply our approach to directly monitor in vitro A-to-I RNA editing activity using recombinantA DAR enzymes. This method improves upon existing inosine chemical-labeling techniques and provides ac ost-effective, rapid, and non-radioactive approach for detecting inosine formation in RNA. We envision this method will improve the study of A-to-I editing and enable better characterization of RNA modification patterns in different settings. RNA is chemically modified by anumber of enzymes after transcription, in turn influencing RNA stability, localizationa nd activity within the cell. Adenosine-to-inosine (A-to-I) RNA editing is one of the most widespread modifications, and is performed by adenosine deaminases acting on RNA (ADARs) (Scheme 1a). [1] Adenosine deaminationc hanges the molecular structurea nd hydrogen-bonding pattern of the nucleobase, and resulting inosines insteadb ase pairw ith cytidinet oe ffectively recode these sites as guanosine. Editings ites within protein-coding mRNAsd irectly alter amino acid sequences and produce different protein isoforms. Non-coding RNAs also undergo extensive editing, including microRNAs and small-interfering RNAs, significantly alteringt heir biosynthesis, localization, and gene regulation properties. [2-3] A-to-I editing is essential for an umber of biological processes including tissue development, [4-5] neurologicalf unction, [6] and immune system activation. [7] Dysfunctional editing is also directlyl inked with autoimmune diseases, [8-9] neurological disorders, [10] and several types of cancer. [11-12] Despite this importance,o ur overall understanding of A-to-I editingr egulation is limited. In particular,w hile many sites have been identified (> 5million), [13-14] it is unclear why certain sites are edited at higherf requency than others and what precise function they each serve. [15] Efforts to map A-to-I locations and ADAR binding sites have revealed that editingp atterns are highly complex and variable in humans, [7, 16-18] and the precise mechanismsb yw hich ADAR enzymes bind to and edit specific RNA sequences remain unclear.T his gap is also significant for therapeutic site-directed RNA editing strategies, [19] as both the design and precise implementation of this machinery is reliant on at horough understanding of ADAR regulation. Detecting inosine formation in RNA is of central importance for characterizing editingm echanisms. While high-throughput RNA sequencin...
Human ADAR3 is a catalytically inactive member of the Adenosine Deaminase Acting on RNA (ADAR) protein family, whose active members catalyze A-to-I RNA editing in metazoans. Until now, the reasons for the catalytic incapability of ADAR3 has not been defined and its biological function rarely explored. Yet, its exclusive expression in the brain and involvement in learning and memory suggest a central role in the nervous system. Here we describe the engineering of a catalytically active ADAR3 enzyme using a combination of computational design and functional screening. Five mutations (A389V, V485I, E527Q, Q549R and Q733D) engender RNA deaminase in human ADAR3. By way of its catalytic activity, the ADAR3 pentamutant was used to identify potential binding targets for wild type ADAR3 in a human glioblastoma cell line. Novel ADAR3 binding sites discovered in this manner include the 3′-UTRs of the mRNAs encoding early growth response 1 (EGR1) and dual specificity phosphatase 1 (DUSP1); both known to be activity-dependent immediate early genes that respond to stimuli in the brain. Further studies reveal that the wild type ADAR3 protein can regulate transcript levels for DUSP1 and EGR1, suggesting a novel role ADAR3 may play in brain function.
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