Allotopic Expression of mRNAs as a Novel Gene Therapy for Encephalomyopathies

Mutation of the mtATP6 gene, which encodes an essential subunit of the F0F1-ATP synthase (Complex V) in mitochondria, is known to cause a group of related encephalomyopathies. The ATP synthase acts as a hydrogen ion transporter that couples ion dissipation with ATP production. Diseases including NARP (neuropathy ataxia and retinitis pigmentosa) and MILS (maternally inherited Leigh's syndrome) are caused by missense mutations in the ATP6 gene. Drosophila melanogaster, the common fruit fly, has a mitochondrial ATP6 missense mutation that models NARP/MILS diseases. Our aim is to develop a transgenic strategy where allotopic expression of a mitochondrial-targeted ATP6 mRNA may serve as a potential gene therapy for these devastating mitochondrial diseases. Mitochondria in metazoans are known to import nuclear encoded 5SrRNAs, which are thought to be essential for mitochondrial protein synthesis. We utilized a cluster of 100 individual 5S rRNA genes found at 56F region of the right arm of chromosome 2 in Drosophila melanogaster. Sequence comparisons revealed 17 groups of genomic variants and 14 processed rRNA counterparts. Identifying which, if any, of the known 5S rRNAs are competent for mitochondrial import was integral to our proposed gene therapy approach. A protocol was developed that utilizes gradient and percoll centrifugation steps to isolate highly purified mitochondria that lack detectable cytosolic contamination. RT-PCR and cloning were used to determine which 5S rRNAs were expressed and localized to the mitochondria. The cytoplasmic and mitochondrial derived clones and gDNA control clones support the assertion that, at least under normal in vivo conditions, ~ 60 % of the identified 5S rRNA genes are not expressed and are likely pseudogenes. One variant, 5S rRNA III, is predominantly expressed and localized to the mitochondria. Also, 8 novel and 3 possible 5S rRNA gene isoforms not currently categorized in sequence databases have been discovered. Clones capable of expressing chimeric rRNA::mRNAs in cells and in vivo were generated. These constructs could later be used to assess the ability of 5S rRNA to direct mitochondrial import of "passenger" mRNAs

Enzyme-catalyzed Degradation of Carbon Nanomaterials

Carbon nanotubes and graphene, the nanoscale sp2 allotropes of carbon, have garnered widespread attention as a result of their remarkable electrical, mechanical, and optical properties and the promise of new technologies that harness these properties. Consequently, these carbon nanomaterials (CNMs) have been employed for diverse applications such as electronics, sensors, composite materials, energy conversion devices, and nanomedicine. The manufacture and eventual disposal of these products may result in the release of CNMs into the environment and subsequent exposure to humans, animals, and vegetation. Given the possible pro-inflammatory and toxic effects of CNMs, much attention has been focused on the distribution, toxicity, and persistence of CNMs both in living systems and the environment. This dissertation will guide the reader though recent studies aimed at elucidating fundamental insight into the persistence of CNMs such as carbon nanotubes (CNTs) and graphene derivatives (i.e., graphene oxide and reduced graphene oxide). In particular, in-test-tube oxidation/degradation of CNMs catalyzed by peroxidase enzymes will be examined, and the current understanding of the mechanisms underlying these processes will be discussed. Finally, an outlook of the current field including in vitro and in vivo biodegradation experiments, which have benefits in terms of human health and environmental safety, and future directions that could have implications for nanomedical applications such as imaging and drug delivery will be presented. Armed with an understanding of how and why CNMs undergo enzyme-catalyzed oxidation/biodegradation, researchers can tailor the structure of CNMs to either promote or inhibit these processes. For example, in nanomedical applications such as drug delivery, the incorporation of carboxylate functional groups could facilitate biodegradation of the nanomaterial after delivery of the cargo. Also, the incorporation of CNMs with defect sites in consumer goods could provide a mechanism that promotes the degradation of these materials once these products reach landfills

Multi-walled carbon nanotubes complement the anti-tumoral effect of 5-Fluorouracil

Multiple-drug resistance in human cancer is a major problem. To circumvent this issue, clinicians combine several drugs. However, this strategy could backfire resulting in more toxic or ineffective treatments. Carbon nanotubes (CNTs), and particularly multi-walled nanotubes (MWCNTs), display intrinsic properties against cancer interfering with microtubule dynamics and triggering anti-proliferative, anti-migratory and cytotoxic effects in vitro that result in tumor growth inhibition in vivo. Remarkably, these effects are maintained in tumors resistant to traditional microtubule-binding chemotherapies such as Taxol®. In the view of these properties, we investigate the use of MWCNTs in the development of active-by-design nanocarriers, attempting to enhance the effect of broadly-used chemotherapies. We compare the cytotoxic and the anti-tumoral effect of 5-Fluorouracil (5-FU) -an antimetabolite treatment of various forms of cancer- with that of the drug physisorbed onto MWCNTs. Our results demonstrate how the total effect of the drug 5-FU is remarkably improved (50% more effective) when delivered intratumorally coupled to MWCNTs both in vitro and in vivo in solid tumoral models. Our results demonstrate how using MWCNTs as anti-cancer drug delivery platforms is a promising approach to boost the efficacy of traditional chemotherapies, while considerably reducing the chances of resistance in cancer cells.This work was founded by the following sources: Spanish MINECO, Instituto de Salud Carlos III, the European Union FEDER funds under Projects ref. PI16/00496 (AES 2016), MAT2015-69508-P, NanoBioApp Network (MINECO-17-MAT2016-81955-REDT) European Union (European Regional Development Fund-ERDF) and INNVAL 16/15, INNVAL 17/11

A new Raman metric for the characterisation of graphene oxide and its derivatives

Raman spectroscopy is among the primary techniques for the characterisation of graphene materials, as it provides insights into the quality of measured graphenes including their structure and conductivity as well as the presence of dopants. However, our ability to draw conclusions based on such spectra is limited by a lack of understanding regarding the origins of the peaks. Consequently, traditional characterisation techniques, which estimate the quality of the graphene material using the intensity ratio between the D and the G peaks, are unreliable for both GO and rGO. Herein we reanalyse the Raman spectra of graphenes and show that traditional methods rely upon an apparent G peak which is in fact a superposition of the G and D’ peaks. We use this understanding to develop a new Raman characterisation method for graphenes that considers the D’ peak by using its overtone the 2D’. We demonstrate the superiority and consistency of this method for calculating the oxygen content of graphenes, and use the relationship between the D’ peak and graphene quality to define three regimes. This has important implications for purification techniques because, once GO is reduced beyond a critical threshold, further reduction offers limited gain in conductivity

Frequency and Spectrum of Genomic Integration of Recombinant Adeno-Associated Virus Serotype 8 Vector in Neonatal Mouse Liver▿

Neonatal injection of recombinant adeno-associated virus serotype 8 (rAAV8) vectors results in widespread transduction in multiple organs and therefore holds promise in neonatal gene therapy. On the other hand, insertional mutagenesis causing liver cancer has been implicated in rAAV-mediated neonatal gene transfer. Here, to better understand rAAV integration in neonatal livers, we investigated the frequency and spectrum of genomic integration of rAAV8 vectors in the liver following intraperitoneal injection of 2.0 × 1011 vector genomes at birth. This dose was sufficient to transduce a majority of hepatocytes in the neonatal period. In the first approach, we injected mice with a β-galactosidase-expressing vector at birth and quantified rAAV integration events by taking advantage of liver regeneration in a chronic hepatitis animal model and following partial hepatectomy. In the second approach, we performed a new, quantitative rAAV vector genome rescue assay by which we identified rAAV integration sites and quantified integrations. As a result, we find that at least ∼0.05% of hepatocytes contained rAAV integration, while the average copy number of integrated double-stranded vector genome per cell in the liver was ∼0.2, suggesting concatemer integration. Twenty-three of 34 integrations (68%) occurred in genes, but none of them were near the mir-341 locus, the common rAAV integration site found in mouse hepatocellular carcinoma. Thus, rAAV8 vector integration occurs preferentially in genes at a frequency of 1 in approximately 103 hepatocytes when a majority of hepatocytes are once transduced in the neonatal period. Further studies are warranted to elucidate the relationship between vector dose and integration frequency or spectrum