Expression of myoglobin in the transgenic mouse brain.
ABSTRACT The main purpose of this study was to express human myoglobin in mouse brain neurons and investigate the effects of this expression on metabolism and blood flow using phosphorous (31P) NMR spectroscopy and NMR perfusion imaging. Transgenic mice expressing brain myoglobin were created using a cDNA sequence for human myoglobin placed under the transcriptional control of either a human platelet-drived grown factor polypeptide B (PDGF-B) promoter sequence or a rat neuron-specific enolase (NSE) promoter sequence. The presence of myoglobin having a functional, reduced-state, heme group was demonstrated by protein analysis and immunocytochemistry. Expression levels were highest in the hippocampus, cerebellum, and cerebral cortex. No gross morphological adaptations of neural tissue resulting from the expression were observed and no statistically significant differences in the energetic state, as measured by 31P NMR, or baseline cortical perfusion, as measured by an NMR perfusion imaging technique, were found.
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ABSTRACT: Application of MRI contrast agents to neural systems research is complicated by the need to deliver agents past the blood-brain barrier or into cells, and the difficulty of targeting agents to specific brain structures or cell types. In the future, these barriers may be wholly or partially overcome using genetic methods for producing and directing MRI contrast. Here we review MRI contrast mechanisms that have used gene expression to manipulate MRI signal in cultured cells or in living animals. We discuss both fully genetic systems involving endogenous biosynthesis of contrast agents, and semi-genetic systems in which expressed proteins influence the localization or activity of exogenous contrast agents. We close by considering which contrast-generating mechanisms might be most suitable for applications in neuroscience, and we ask how genetic control machinery could be productively combined with existing molecular agents to enable next-generation neuroimaging experiments.Magnetic Resonance Imaging 08/2007; 25(6):1004-10. DOI:10.1016/j.mri.2006.11.027 · 2.02 Impact Factor
Article: Metalloprotein-based MRI probes[Show abstract] [Hide abstract]
ABSTRACT: Metalloproteins have long been recognized as key determinants of endogenous contrast in magnetic resonance imaging (MRI) of biological subjects. More recently, both natural and engineered metalloproteins have been harnessed as biotechnological tools to probe gene expression, enzyme activity, and analyte concentrations by MRI. Metalloprotein MRI probes are paramagnetic and function by analogous mechanisms to conventional gadolinium or iron oxide-based MRI contrast agents. Compared with synthetic agents, metalloproteins typically offer worse sensitivity, but the possibilities of using protein engineering and targeted gene expression approaches in conjunction with metalloprotein contrast agents are powerful and sometimes definitive strengths. This review summarizes theoretical and practical aspects of metalloprotein-based contrast agents, and discusses progress in the exploitation of these proteins for molecular imaging applications.FEBS letters 01/2013; 587(8). DOI:10.1016/j.febslet.2013.01.044 · 3.34 Impact Factor
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ABSTRACT: Nerve globins are present in nonvertebrates and vertebrates, the first nerve globin having been recognized in the nerve cord of the polychaete annelid Aphrodite aculeata in 1872. Later, in 2000, the first vertebrate nerve globin, named neuroglobin (Ngb), has been identified in neuronal tissues of humans and mice. Recently, cytoglobin, hemoglobin, and myoglobin have also been reported to be expressed in the mammalian nervous system. The concentration of mammalian nerve globins is ∼1 μM, with the exception of Ngb that reaches approximately 100-200 μM only in the retina rod cells. Mammalian nerve globins have been hypothesized to be involved in the excitability of the nervous system, in the metabolism of reactive nitrogen and oxygen species, and in intracellular signaling pathways leading to the neuronal cell survival. Only in retina cells, mammalian Ngb may help to sustain O2 supply to mitochondria, thereby supporting the visual process in the eye. Here, the putative roles of mammalian nerve globins are reviewed. © 2014 IUBMB Life, 2014.International Union of Biochemistry and Molecular Biology Life 04/2014; 66(4). DOI:10.1002/iub.1267 · 2.76 Impact Factor