Articles by Marguerite K. McDonald in JoVE
Purification and microRNA Profiling of Exosomes Derived from Blood and Culture Media Marguerite K. McDonald1, Kathryn E. Capasso1, Seena K. Ajit1 1Department of Pharmacology & Physiology, Drexel University College of Medicine The presence of stable microRNAs (miRNAs) in exosomes has generated immense interest as a novel mode of intercellular communication, for their potential utility as biomarkers and as a route for therapeutic intervention. Here we demonstrate exosome purification from blood and culture media followed by quantitative PCR to identify miRNAs being transported.
Other articles by Marguerite K. McDonald on PubMed
The Handling of the Mechanistic Probe 5-fluorouridine by the Pseudouridine Synthase TruA and Its Consistency with the Handling of the Same Probe by the Pseudouridine Synthases TruB and RluA Biochemistry. Jan, 2011 | Pubmed ID: 21142053 RNA containing 5-fluorouridine (F(5)U) had previously been used to examine the mechanism of the pseudouridine synthase TruA, formerly known as pseudouridine synthase I [Gu et al. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 14270-14275]. From that work, it was reasonably concluded that the pseudouridine synthases proceed via a mechanism involving a Michael addition by an active site aspartic acid residue to the pyrimidine ring of uridine or F(5)U. Those conclusions rested on the assumption that the hydrate of F(5)U was obtained after digestion of the product RNA and that hydration resulted from hydrolysis of the ester intermediate between the aspartic acid residue and F(5)U. As reported here, (18)O labeling definitively demonstrates that ester hydrolysis does not give rise to the observed hydrated product and that digestion generates not the expected mononucleoside product but rather a dinucleotide between a hydrated isomer of F(5)U and the following nucleoside in RNA. The discovery that digestion products are dinucleotides accounts for the previously puzzling differences in the isolated products obtained following the action of the pseudouridine synthases TruB and RluA on F(5)U in RNA.
Subcellular Knockout of Importin Î²1 Perturbs Axonal Retrograde Signaling Neuron. Jul, 2012 | Pubmed ID: 22841314 Subcellular localization of mRNA enables compartmentalized regulation within large cells. Neurons are the longest known cells; however, so far, evidence is lacking for an essential role of endogenous mRNA localization in axons. Localized upregulation of Importin Î²1 in lesioned axons coordinates a retrograde injury-signaling complex transported to the neuronal cell body. Here we show that a long 3' untranslated region (3' UTR) directs axonal localization of Importin Î²1. Conditional targeting of this 3' UTR region in mice causes subcellular loss of Importin Î²1 mRNA and protein in axons, without affecting cell body levels or nuclear functions in sensory neurons. Strikingly, axonal knockout of Importin Î²1 attenuates cell body transcriptional responses to nerve injury and delays functional recovery in vivo. Thus, localized translation of Importin Î²1 mRNA enables separation of cytoplasmic and nuclear transport functions of importins and is required for efficient retrograde signaling in injured axons.