Carlos J. Gimeno

Cloning and Characterization of an Uncoupling Protein Homolog: A Potential Molecular Mediator of Human Thermogenesis

We have identified a novel cDNA encoding a protein highly homologous to the mammalian brown fat uncoupling protein (UCP). Unlike the known UCP, which is expressed specifically in brown adipose tissue, the UCP homolog (UCPH) mRNA is expressed in a variety of tissues, with predominant expression in human white adipose tissue and skeletal muscle. In the white adipose tissue of ob/ob and db/db mice, the UCPH transcript is induced approximately fivefold relative to lean littermate controls. Expression of murine UCPH in yeast results in growth inhibition under conditions that require aerobic respiration, but does not affect growth under anaerobic conditions. Furthermore, UCPH expression in yeast causes a decrease in the mitochondrial membrane potential, as judged by staining with the potential-sensitive dye DiOC6. These observations suggest that UCPH, like UCP, uncouples oxidative phosphorylation. The possibility that the UCPH protein is an important mediator of human thermogenesis is discussed.

[54] In vivo oxidative DNA damage : measurement of 8-hydroxy-2'-deoxyguanosine in DNA and urine by high-performance liquid chromatography with electrochemical detection

Abstract HPLC with electrochemical detection is a highly sensitive and selective method for detecting the oxidatively modified DNA residue oh 8 dG. By this method, the detection of oh 8 dG from DNA and urine offers a powerful approach for assessing in vivo oxidative damage. Application of this technique to the detection of oh 8 dG from DNA permits the quantitation of the steady-state levels of this oxidatively modified deoxynucleoside and overcomes the detection problems associated with the extremely low levels present in DNA. In addition, the selectivity gained by this detection method eliminates the problem of separating the signal for oh 8 dG from normal deoxynucleosides. The quantitation of oh gdG in urine complements the measurement of oh 8 dG in DNA by estimating cumulative oxidative DNA damage in the body. In addition, the urinary assay provides a noninvasive means of measuring this type of damage in laboratory animals and human populations. Thus, an individual animal or human subject may be monitored over time, possibly under various prooxidant conditions, using oh 8 dG as a sensitive marker for oxidative DNA damage. This analytical approach may allow one to estimate the exposure of an individual to prooxidant conditions associated with lifestule, genetic predisposition, degenerative diseases, and environmental toxins.