Department of Neurology, Duke University Medical Center, Durham, NC 27710, USA.
Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC 27710, USA.
Biochim Biophys Acta Mol Basis Dis. 2017 Mar;1863(3):810-816. doi: 10.1016/j.bbadis.2017.01.004. Epub 2017 Jan 6.
Chromosome 19q13.32 is a gene rich region, and has been implicated in multiple human phenotypes in adulthood including lipids traits, Alzheimer's disease, and longevity. Peroxisome Proliferator Activated Receptor Gamma (PPARγ) is a ligand-activated nuclear transcription factor that plays a role in human complex traits that are also genetically associated with the chromosome 19q13.32 region. Here, we study the effects of PPARγ on the regional expression regulation of the genes clustered within chromosome 19q13.32, specifically TOMM40, APOE, and APOC1, applying two complementary approaches. Using the short hairpin RNA (shRNA) method in the HepG2 cell-line we knocked down PPARγ expression and measured the effect on mRNA expression. We discovered PPARγ knock down increased the levels of TOMM40-, APOE-, and APOC1-mRNAs, with the highest increase in expression observed for APOE-mRNA. To complement the PPARγ knockdown findings we also examined the effects of low doses of PPARγ agonists (nM range) on mRNA expression of these genes. Low (nM) concentrations of pioglitazone (Pio) decreased transcription of TOMM40, APOE, and APOC1 genes, with the lowest mRNA levels for each gene observed at 1.5nM. Similar to the effect of PPARγ knockdown, the strongest response to pioglitazone was also observed for APOE-mRNA, and rosiglitazone (Rosi), another PPARγ agonist, produced results that were consistent with these. In conclusion, our results further established a role for PPARγ in regional transcriptional regulation of chr19q13.32, underpinning the association between PPARγ, the chr19q13.32 genes cluster, and human complex traits and disease.
19 号染色体 q13.32 是一个基因丰富的区域，与成年人的多种表型有关，包括脂质特征、阿尔茨海默病和长寿。过氧化物酶体增殖物激活受体 γ（PPARγ）是一种配体激活的核转录因子，在人类复杂特征中发挥作用，这些特征也与 19 号染色体 q13.32 区域的遗传有关。在这里，我们研究了 PPARγ 对位于 19 号染色体 q13.32 区域内基因簇的区域表达调控的影响，特别是 TOMM40、APOE 和 APOC1，采用了两种互补的方法。我们在 HepG2 细胞系中使用短发夹 RNA（shRNA）方法敲低 PPARγ 的表达，并测量其对 mRNA 表达的影响。我们发现，PPARγ 敲低增加了 TOMM40、APOE 和 APOC1-mRNA 的水平，其中 APOE-mRNA 的表达增加最为明显。为了补充 PPARγ 敲低的发现，我们还检查了低剂量的 PPARγ 激动剂（纳摩尔范围）对这些基因的 mRNA 表达的影响。低浓度（纳摩尔）的吡格列酮（Pio）降低了 TOMM40、APOE 和 APOC1 基因的转录，每个基因的最低 mRNA 水平在 1.5nM 时观察到。与 PPARγ 敲低的作用相似，吡格列酮对 APOE-mRNA 的反应也最强，另一种 PPARγ 激动剂罗格列酮（Rosi）的结果也与此一致。总之，我们的结果进一步确立了 PPARγ 在 chr19q13.32 区域转录调控中的作用，为 PPARγ、chr19q13.32 基因簇与人类复杂特征和疾病之间的关联提供了依据。
