Functional characterization of brown adipose tissue in phylogenetically ancient eutherian mammals, Afrotheria

点击翻译按钮获取中文摘要

This study aims to further investigate the role of brown adipose tissue (BAT), the function of its thermogenic protein uncoupling protein-1 (UCP1) and the plasticity of adaptive non-shivering thermogenesis in the evolutionary most basal group of the eutherian mammals, the Afrotheria (Elephantulus. myurus, Elephantulus edwardii, Amblysomus hottentottus longiceps, Echinops telfairi). The central goal of our proposed project is to reveal whether or not Afrotherian thermogenic brown adipose already conveys all currently known key features necessary to infer classical non-shivering thermogenesis. Our approach is scaling from in vivo metabolic responses (torpor behaviour, capacity for nonshivering heat production) in free ranging animals, during different seasons, to the molecular mechanism of heat production. Molecular parameters and bioenergetics in isolated BAT mitochondria of E. edwardii and E. telfairi will be investigated with respect to sophisticated technologies accessing thermogenic proteins by mitochondrial proton leak kinetics in vitro and in vivo. For the latter, UCP1 cDNAs from E. myurus, E. edwardii, A. h. longiceps, and E. telfairi will be cloned and stably transfected into in HEK293 (human embryonic kidney) cells. Measuring protein function in front of an identical genetical, cellular and mitochondrial background will allow the determination of differences in UCP1 activity and regulation within Afrotherians and in comparison to modern eutherians, as well as the identification of conserved structure-function relationships.