Reconstruction and expression of the MRI-contrast protein, ferritin, with recombinant rabies vectors

Chemistry and biology of ferritin

Iron is an essential element required by cells and has been described as a key player in ferroptosis. Ferritin operates as a fundamental iron storage protein in cells forming multimeric assemblies with crystalline iron cores. We discuss the latest findings on ferritin structure and activity and its link to cell metabolism and ferroptosis. The chemistry of iron, including its oxidation states, is important for its biological functions, its reactivity, and the biology of ferritin. Ferritin can be localized in different cellular compartments and secreted by cells with a variety of functions depending on its spatial context. Here, we discuss how cellular ferritin localization is tightly linked to its function in a tissue-specific manner, and how impairment of iron homeostasis is implicated in diseases, including cancer and coronavirus disease 2019. Ferritin is a potential biomarker and we discuss latest research where it has been employed for imaging purposes and drug delivery.

Reporter gene approaches for mapping cell fate decisions by MRI: promises and pitfalls

The central dogma of molecular biology, namely the process by which information encoded in the DNA serves as the template for transcriptional activation of specific mRNA resulting in temporal and spatial control of the translation of specific proteins, stands at the basis of normal and pathological cellular processes. Serving as the primary mechanism linking genotype to phenotype, it is clearly of significant interest for in vivo imaging. While classically, imaging revolutionized the ability to phenotype the anatomical and physiological impact of induction of changes in gene expression, the preceding molecular events remained invisible. Reporter gene-based imaging techniques provide a window for in vivo visualization of such transcriptional activation events. In addition to the widespread use of fluorescent and bioluminescent reporter genes and development of a number of reporter genes for positron emission tomography (PET) imaging, there has been significant progress in the development of reporter genes for MRI. With the development of strategies for cellular based therapies, such imaging tools could become central components for personalized patient monitoring.

Development of recombinant rabies viruses vectors with Gaussia luciferase reporter based on Chinese vaccine strain CTN181

The recombinant rabies virus (RV) vectors encoding the secreted gene marker Gaussia luciferase (Gluc) were generated based on Chinese vaccine strain CTN181. Vectors included replication competent CTN-Gluc, CTN/G_Q333R-Gluc, in which the amino acid in position 333 of glycoprotein was mutated from glutamine (Q) to arginine (R), and replication constrained CTNΔG-Gluc, in which the glycoprotein encoding gene (G) was deleted. The growth of recombinant RVs in transfected cells was confirmed through biochemical assays of Gluc activities. Gluc expression in recombinant CTNΔG-Gluc virus was highest while that in CTN/G_Q333R-Gluc virus was lowest. The optimal time to harvest recombinant RVs was determined and the function of pathogenic and nonpathogenic rabies glycoprotein in virus recovery was examined. The addition of glycoprotein was slightly beneficial for virus recovery and the titer of rescued virus was lowered even when the amino acid in G333 position of glycoprotein was mutated from nonpathogenic Gln to pathogenic Arg. Conclusions: Viral vectors based on a human rabies vaccine strain CTN181 were successful. Gluc was useful as an in vitro gene marker for monitoring the growth of recombinant RVs iteratively in cell culture.