Fat graft survival requires metabolic reprogramming towards glycolytic pathway

Background: The mechanisms underlying fat graft survival are poorly understood. Here, we performed unbiased transcriptomics analysis of mouse fat graft model to find out the molecular mechanism of free fat graft survival. Methods: We conducted RNA-sequencing (RNA-seq) analysis of mouse free subcutaneous fat graft model at day 3 and 7 following grafting (n=5). High-throughput sequencing was performed as paired-end using NovaSeq6000 (Illumina, CA, USA). The calculated transcripts per million (TPM) values were processed for principal component analysis (PCA), unsupervised hierarchically clustered heat map generation, and Gene set enrichment analysis. Results: PCA and heat map data revealed global differences in the transcriptome of grafted fat when compared with non-graft control. The top meaningful up-regulated gene sets in the grafted fat were related to epithelial mesenchymal transition and hypoxia by day 3, and angiogenesis by day 7. Mechanistically, the glycolysis pathway was commonly upregulated in the grafted fat at day 3 (FDR q=0.012) and day 7 (FDR q=0.084). In subsequent experiments, pharmacological inhibition of glycolytic pathway in the grafted fat with 2-Deoxy-D-glucose (2-DG) significantly suppressed fat graft retention rates, both grossly and microscopically (n=5). Conclusions: Global transcriptome analysis and pharmacologic inhibition study revealed that free adipose tissue grafts undergo metabolic reprogramming towards glycolytic pathway. Whether targeting the pathway wound enhance graft survival rate remains to be investigated. Adipose mRNA profiles of fat grafts: 1) control, 2) 3 day graft, 3) 7 day graft

研究背景：游离脂肪移植存活的相关分子机制目前尚不明晰。本研究针对小鼠脂肪移植模型开展无偏转录组学分析，以探究游离脂肪移植存活的分子机制。
研究方法：我们对移植后第3天和第7天的小鼠皮下游离脂肪移植模型开展RNA测序（RNA-seq）分析（每组n=5）。采用美国加利福尼亚州Illumina公司的NovaSeq6000平台进行双端高通量测序。对计算得到的每百万转录本（transcripts per million, TPM）值进行主成分分析（principal component analysis, PCA）、无监督分层聚类热图构建以及基因集富集分析（Gene Set Enrichment Analysis, GSEA）。
研究结果：主成分分析与热图结果显示，与未移植的对照组相比，移植脂肪的转录组存在全局表达差异。移植后第3天，移植脂肪中显著上调的核心基因集主要富集于上皮间质转化（epithelial mesenchymal transition）与缺氧（hypoxia）通路；移植后第7天则主要富集于血管生成（angiogenesis）通路。机制层面，糖酵解通路在移植后第3天（错误发现率q值=0.012）与第7天（错误发现率q值=0.084）的移植脂肪中均呈现普遍上调。后续实验中，采用2-脱氧葡萄糖（2-Deoxy-D-glucose, 2-DG）对移植脂肪的糖酵解通路进行药理学抑制后，无论宏观还是微观层面，脂肪移植的留存率均显著降低（每组n=5）。
研究结论：全局转录组分析与药理学抑制实验表明，游离脂肪组织移植会发生向糖酵解通路的代谢重编程。靶向该通路是否可提升移植存活率仍有待进一步研究。本数据集包含脂肪移植的脂肪组织mRNA表达谱：1）对照组，2）移植后3天组，3）移植后7天组