Transcriptome analysis in adipose tissues of BAF60a knockout mice

Brown and beige fat share a remarkably similar transcriptional program that supports fuel oxidation and thermogenesis. The chromatin-remodeling machinery that governs genome accessibility and renders adipocytes poised for thermogenic activation remains elusive. BAF60a serves an indispensable role in cold-induced thermogenesis in brown fat. Surprisingly, fat-specific BAF60a inactivation triggers more pronounced browning of inguinal white adipose tissue. These results suggest a dichotomous role of BAF60a-mediated chromatin remodeling in transcriptional control of brown and beige gene programs. To elucidate the mechanism, we performed microarray annalysis in inguinal white adipose tissues from mice after chronic cold exposure. Adipose-specific Baf60a knockout (AKO) and control (flox) mice of 9 month old were subjected to either ambient temperature (RT) or chronic cold exposure (Cold). For mice under cold challenge, they went through a gradual adaptation. After reaching 10oC, the mice were maintained for another 7 days before euthanization. Inguinal white adipose tissues were havested for RNA isolation. After quantification, equal amount of RNA from 1 or 2 mice were pooled for microarray analysis.

棕色脂肪与米色脂肪共享一套高度相似的转录程序（transcriptional program），可介导燃料氧化与产热生理过程。目前，调控基因组可及性并使脂肪细胞处于产热激活预备状态的染色质重塑（chromatin-remodeling）机制仍未明确。BAF60a在棕色脂肪的冷诱导产热过程中发挥不可或缺的作用。令人意外的是，脂肪组织特异性BAF60a敲除可诱导腹股沟白色脂肪组织发生更为显著的褐变。上述结果表明，BAF60a介导的染色质重塑在棕色与米色脂肪基因程序的转录调控中发挥双重作用。为阐明该调控机制，本研究对慢性冷暴露后的小鼠腹股沟白色脂肪组织开展了微阵列分析（microarray）。将9月龄的脂肪组织特异性BAF60a敲除（AKO）小鼠与同基因型对照（flox）小鼠分为两组，分别置于室温（RT）环境或接受慢性冷暴露（Cold）处理。接受冷暴露刺激的小鼠先进行逐步适应：待环境温度降至10℃后，维持该温度饲养7天，随后实施安乐死。收集腹股沟白色脂肪组织用于RNA提取。RNA定量完成后，将1至2只小鼠的等量RNA混合后用于微阵列分析。