Gospodarska Emilia, Nowialis Pawel, Kozak Leslie P
From the Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland.
From the Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland
J Biol Chem. 2015 Mar 27;290(13):8243-55. doi: 10.1074/jbc.M115.637785. Epub 2015 Feb 1.
To determine the differences between brown adipocytes from interscapular brown tissue (iBAT) and those induced in white adipose tissue (WAT) with respect to their thermogenic capacity, we examined two essential characteristics: the dynamics of mitochondrial turnover during reversible transitions from 29 °C to 4 °C and the quantitative relationship between UCP1 and selected subunits of mitochondrial respiratory complex in the fully recruited state. To follow the kinetics of induction and involution of mitochondria, we determined the expression pattern of UCP1 and other mitochondrial proteins as well as analyzed mtDNA content after cold stimulation and reacclimation to thermoneutrality. We showed that UCP1 turnover is very different in iBAT and inguinal WAT (ingWAT); the former showed minimal changes in protein content, whereas the latter showed major changes. Similarly, in iBAT both mtDNA content and the expression of mitochondrial proteins were stable and expressed at similar levels during reversible transitions from 29 °C to 4 °C, whereas ingWAT revealed dynamic changes. Further analysis showed that in iBAT, the expression patterns for UCP1 and other mitochondrial proteins resembled each other, whereas in ingWAT, UCP1 varied ∼100-fold during the transition from cold to warmth, and no other mitochondrial proteins matched UCP1. In turn, quantitative analysis of thermogenic capacity determined by estimating the proportion of UCP1 to respiratory complex components showed no significant differences between brown and brite adipocytes, suggesting similar thermogenic potentiality. Our results indicate that dynamics of brown adipocytes turnover during reversible transition from warm to cold may determine the thermogenic capacity of an individual in a changing temperature environment.
为了确定肩胛间棕色脂肪组织（iBAT）来源的棕色脂肪细胞与白色脂肪组织（WAT）诱导产生的棕色脂肪细胞在产热能力方面的差异，我们研究了两个关键特性：从29°C可逆转变至4°C过程中线粒体更新的动态变化，以及完全激活状态下UCP1与线粒体呼吸复合体选定亚基之间的定量关系。为了追踪线粒体诱导和退化的动力学过程，我们测定了UCP1和其他线粒体蛋白的表达模式，并分析了冷刺激及恢复至热中性状态后的线粒体DNA含量。我们发现，iBAT和腹股沟白色脂肪组织（ingWAT）中的UCP1更新存在很大差异；前者蛋白质含量变化极小，而后者变化显著。同样，在iBAT中，从29°C可逆转变至4°C过程中，线粒体DNA含量和线粒体蛋白表达均保持稳定且水平相近，而ingWAT则呈现出动态变化。进一步分析表明，在iBAT中，UCP1和其他线粒体蛋白的表达模式相似，而在ingWAT中，从寒冷到温暖的转变过程中UCP1变化约100倍，且没有其他线粒体蛋白与UCP1匹配。反过来，通过估计UCP1与呼吸复合体成分的比例来定量分析产热能力，结果显示棕色脂肪细胞和米色脂肪细胞之间没有显著差异，表明它们具有相似的产热潜力。我们的结果表明，在从温暖到寒冷的可逆转变过程中，棕色脂肪细胞更新的动态变化可能决定个体在不断变化的温度环境中的产热能力。
